source: rtems/cpukit/mghttpd/mongoose.c @ 9b4422a2

/*
 * Copyright (c) 2004-2009 Sergey Lyubka
 * Portions Copyright (c) 2009 Gilbert Wellisch
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#if defined(_WIN32)
#define _CRT_SECURE_NO_WARNINGS /* Disable deprecation warning in VS2005 */
#endif /* _WIN32 */

#ifndef _WIN32_WCE /* Some ANSI #includes are not available on Windows CE */
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#endif /* !_WIN32_WCE */

#include <time.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>

#if defined(_WIN32)             /* Windows specific #includes and #defines */
#define _WIN32_WINNT    0x0400  /* To make it link in VS2005 */
#include <windows.h>

#ifndef _WIN32_WCE
#include <process.h>
#include <direct.h>
#include <io.h>
#else /* _WIN32_WCE */
/* Windows CE-specific definitions */
#include <winsock2.h>
#define NO_CGI  /* WinCE has no pipes */
#define NO_SSI  /* WinCE has no pipes */

#define FILENAME_MAX    MAX_PATH
#define BUFSIZ          4096
typedef long off_t;

#define errno                   GetLastError()
#define strerror(x)             _ultoa(x, (char *) _alloca(sizeof(x) *3 ), 10)
#endif /* _WIN32_WCE */

#define EPOCH_DIFF      0x019DB1DED53E8000 /* 116444736000000000 nsecs */
#define RATE_DIFF       10000000 /* 100 nsecs */
#define MAKEUQUAD(lo, hi)       ((uint64_t)(((uint32_t)(lo)) | \
                                ((uint64_t)((uint32_t)(hi))) << 32))
#define SYS2UNIX_TIME(lo, hi) \
        (time_t) ((MAKEUQUAD((lo), (hi)) - EPOCH_DIFF) / RATE_DIFF)

/*
 * Visual Studio 6 does not know __func__ or __FUNCTION__
 * The rest of MS compilers use __FUNCTION__, not C99 __func__
 * Also use _strtoui64 on modern M$ compilers
 */
#if defined(_MSC_VER) && _MSC_VER < 1300
#define STRX(x)                 #x
#define STR(x)                  STRX(x)
#define __func__                "line " STR(__LINE__)
#define strtoull(x, y, z)       strtoul(x, y, z)
#else
#define __func__                __FUNCTION__
#define strtoull(x, y, z)       _strtoui64(x, y, z)
#endif /* _MSC_VER */

#define ERRNO                   GetLastError()
#define NO_SOCKLEN_T
#define SSL_LIB                 "ssleay32.dll"
#define CRYPTO_LIB              "libeay32.dll"
#define DIRSEP                  '\\'
#define IS_DIRSEP_CHAR(c)       ((c) == '/' || (c) == '\\')
#define O_NONBLOCK              0
#define EWOULDBLOCK             WSAEWOULDBLOCK
#define _POSIX_
#define INT64_FMT               "I64"

#define SHUT_WR                 1
#define snprintf                _snprintf
#define vsnprintf               _vsnprintf
#define sleep(x)                Sleep((x) * 1000)

#define popen(x, y)             _popen(x, y)
#define pclose(x)               _pclose(x)
#define close(x)                _close(x)
#define dlsym(x,y)              GetProcAddress((HINSTANCE) (x), (y))
#define RTLD_LAZY               0
#define fseeko(x, y, z)         fseek((x), (y), (z))
#define fdopen(x, y)            _fdopen((x), (y))
#define write(x, y, z)          _write((x), (y), (unsigned) z)
#define read(x, y, z)           _read((x), (y), (unsigned) z)
#define flockfile(x)            (void) 0
#define funlockfile(x)          (void) 0

#if !defined(fileno)
#define fileno(x)               _fileno(x)
#endif /* !fileno MINGW #defines fileno */

typedef HANDLE pthread_mutex_t;
typedef HANDLE pthread_cond_t;
typedef DWORD pthread_t;
#define pid_t HANDLE    /* MINGW typedefs pid_t to int. Using #define here. */

struct timespec {
        long tv_nsec;
        long tv_sec;
};

static int pthread_mutex_lock(pthread_mutex_t *);
static int pthread_mutex_unlock(pthread_mutex_t *);

#if defined(HAVE_STDINT)
#include <stdint.h>
#else
typedef unsigned int            uint32_t;
typedef unsigned short          uint16_t;
typedef unsigned __int64        uint64_t;
typedef __int64                 int64_t;
#define INT64_MAX               9223372036854775807
#endif /* HAVE_STDINT */

/*
 * POSIX dirent interface
 */
struct dirent {
        char    d_name[FILENAME_MAX];
};

typedef struct DIR {
        HANDLE                  handle;
        WIN32_FIND_DATAW        info;
        struct dirent           result;
} DIR;

#else                           /* UNIX  specific       */
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/select.h>
#if HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#if defined(__rtems__)
#define flockfile(x)            (void) 0
#define funlockfile(x)          (void) 0
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <stdint.h>
#include <inttypes.h>

#include <pwd.h>
#include <unistd.h>
#include <dirent.h>
#if HAVE_DLFCN_H
#include <dlfcn.h>
#endif
#include <pthread.h>
#define SSL_LIB                 "libssl.so"
#define CRYPTO_LIB              "libcrypto.so"
#define DIRSEP                  '/'
#define IS_DIRSEP_CHAR(c)       ((c) == '/')
#define O_BINARY                0
#define closesocket(a)          close(a)
#define mg_fopen(x, y)          fopen(x, y)
#define mg_mkdir(x, y)          mkdir(x, y)
#define mg_remove(x)            remove(x)
#define mg_rename(x, y)         rename(x, y)
#define ERRNO                   errno
#define INVALID_SOCKET          (-1)
#define INT64_FMT               PRId64
typedef int SOCKET;

#endif /* End of Windows and UNIX specific includes */

#include "mongoose.h"

#define MONGOOSE_VERSION        "2.9"
#define PASSWORDS_FILE_NAME     ".htpasswd"
#define CGI_ENVIRONMENT_SIZE    4096
#define MAX_CGI_ENVIR_VARS      64
#define MAX_REQUEST_SIZE        8192
#define MAX_LISTENING_SOCKETS   10
#define MAX_CALLBACKS           20
#define ARRAY_SIZE(array)       (sizeof(array) / sizeof(array[0]))
#define DEBUG_MGS_PREFIX        "*** Mongoose debug *** "

#if defined(DEBUG)
#define DEBUG_TRACE(x) do {printf x; putchar('\n'); fflush(stdout);} while (0)
#else
#define DEBUG_TRACE(x)
#endif /* DEBUG */

/*
 * Darwin prior to 7.0 and Win32 do not have socklen_t
 */
#ifdef NO_SOCKLEN_T
typedef int socklen_t;
#endif /* NO_SOCKLEN_T */

#if !defined(FALSE)
enum {FALSE, TRUE};
#endif /* !FALSE */

typedef int bool_t;
typedef void * (*mg_thread_func_t)(void *);

static const char *http_500_error = "Internal Server Error";

/*
 * Snatched from OpenSSL includes. I put the prototypes here to be independent
 * from the OpenSSL source installation. Having this, mongoose + SSL can be
 * built on any system with binary SSL libraries installed.
 */
typedef struct ssl_st SSL;
typedef struct ssl_method_st SSL_METHOD;
typedef struct ssl_ctx_st SSL_CTX;

#define SSL_ERROR_WANT_READ     2
#define SSL_ERROR_WANT_WRITE    3
#define SSL_FILETYPE_PEM        1
#define CRYPTO_LOCK             1

/*
 * Dynamically loaded SSL functionality
 */
struct ssl_func {
        const char      *name;          /* SSL function name    */
        void            (*ptr)(void);   /* Function pointer     */
};

#define SSL_free(x)     (* (void (*)(SSL *)) ssl_sw[0].ptr)(x)
#define SSL_accept(x)   (* (int (*)(SSL *)) ssl_sw[1].ptr)(x)
#define SSL_connect(x)  (* (int (*)(SSL *)) ssl_sw[2].ptr)(x)
#define SSL_read(x,y,z) (* (int (*)(SSL *, void *, int))                \
                                ssl_sw[3].ptr)((x),(y),(z))
#define SSL_write(x,y,z) (* (int (*)(SSL *, const void *,int))          \
                                ssl_sw[4].ptr)((x), (y), (z))
#define SSL_get_error(x,y)(* (int (*)(SSL *, int)) ssl_sw[5])((x), (y))
#define SSL_set_fd(x,y) (* (int (*)(SSL *, SOCKET)) ssl_sw[6].ptr)((x), (y))
#define SSL_new(x)      (* (SSL * (*)(SSL_CTX *)) ssl_sw[7].ptr)(x)
#define SSL_CTX_new(x)  (* (SSL_CTX * (*)(SSL_METHOD *)) ssl_sw[8].ptr)(x)
#define SSLv23_server_method()  (* (SSL_METHOD * (*)(void)) ssl_sw[9].ptr)()
#define SSL_library_init() (* (int (*)(void)) ssl_sw[10].ptr)()
#define SSL_CTX_use_PrivateKey_file(x,y,z)      (* (int (*)(SSL_CTX *, \
                const char *, int)) ssl_sw[11].ptr)((x), (y), (z))
#define SSL_CTX_use_certificate_file(x,y,z)     (* (int (*)(SSL_CTX *, \
                const char *, int)) ssl_sw[12].ptr)((x), (y), (z))
#define SSL_CTX_set_default_passwd_cb(x,y) \
        (* (void (*)(SSL_CTX *, mg_spcb_t)) ssl_sw[13].ptr)((x),(y))
#define SSL_CTX_free(x) (* (void (*)(SSL_CTX *)) ssl_sw[14].ptr)(x)

#define CRYPTO_num_locks() (* (int (*)(void)) crypto_sw[0].ptr)()
#define CRYPTO_set_locking_callback(x)                                  \
                (* (void (*)(void (*)(int, int, const char *, int)))    \
                crypto_sw[1].ptr)(x)
#define CRYPTO_set_id_callback(x)                                       \
        (* (void (*)(unsigned long (*)(void))) crypto_sw[2].ptr)(x)

/*
 * set_ssl_option() function when called, updates this array.
 * It loads SSL library dynamically and changes NULLs to the actual addresses
 * of respective functions. The macros above (like SSL_connect()) are really
 * just calling these functions indirectly via the pointer.
 */
static struct ssl_func  ssl_sw[] = {
        {"SSL_free",                    NULL},
        {"SSL_accept",                  NULL},
        {"SSL_connect",                 NULL},
        {"SSL_read",                    NULL},
        {"SSL_write",                   NULL},
        {"SSL_get_error",               NULL},
        {"SSL_set_fd",                  NULL},
        {"SSL_new",                     NULL},
        {"SSL_CTX_new",                 NULL},
        {"SSLv23_server_method",        NULL},
        {"SSL_library_init",            NULL},
        {"SSL_CTX_use_PrivateKey_file", NULL},
        {"SSL_CTX_use_certificate_file",NULL},
        {"SSL_CTX_set_default_passwd_cb",NULL},
        {"SSL_CTX_free",                NULL},
        {NULL,                          NULL}
};

#if !defined(NO_SSL)
/*
 * Similar array as ssl_sw. These functions are located in different lib.
 */
static struct ssl_func  crypto_sw[] = {
        {"CRYPTO_num_locks",            NULL},
        {"CRYPTO_set_locking_callback", NULL},
        {"CRYPTO_set_id_callback",      NULL},
        {NULL,                          NULL}
};
#endif

/*
 * Month names
 */
static const char *month_names[] = {
        "Jan", "Feb", "Mar", "Apr", "May", "Jun",
        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

/*
 * Unified socket address. For IPv6 support, add IPv6 address structure
 * in the union u.
 */
struct usa {
        socklen_t len;
        union {
                struct sockaddr sa;
                struct sockaddr_in sin;
        } u;
};

/*
 * Specifies a string (chunk of memory).
 * Used to traverse comma separated lists of options.
 */
struct vec {
        const char      *ptr;
        size_t          len;
};

/*
 * Structure used by mg_stat() function. Uses 64 bit file length.
 */
struct mgstat {
        bool_t          is_directory;   /* Directory marker             */
        int64_t         size;           /* File size                    */
        time_t          mtime;          /* Modification time            */
};

struct mg_option {
        const char      *name;
        const char      *description;
        const char      *default_value;
        int             index;
        bool_t (*setter)(struct mg_context *, const char *);
};

/*
 * Numeric indexes for the option values in context, ctx->options
 */
enum mg_option_index {
        OPT_ROOT, OPT_INDEX_FILES, OPT_PORTS, OPT_DIR_LIST, OPT_CGI_EXTENSIONS,
        OPT_CGI_INTERPRETER, OPT_CGI_ENV, OPT_SSI_EXTENSIONS, OPT_AUTH_DOMAIN,
        OPT_AUTH_GPASSWD, OPT_AUTH_PUT, OPT_ACCESS_LOG, OPT_ERROR_LOG,
        OPT_SSL_CERTIFICATE, OPT_ALIASES, OPT_ACL, OPT_UID, OPT_PROTECT,
        OPT_SERVICE, OPT_HIDE, OPT_ADMIN_URI, OPT_MAX_THREADS, OPT_IDLE_TIME,
        OPT_MIME_TYPES,
        NUM_OPTIONS
};

/*
 * Structure used to describe listening socket, or socket which was
 * accept()-ed by the master thread and queued for future handling
 * by the worker thread.
 */
struct socket {
        SOCKET          sock;           /* Listening socket             */
        struct usa      lsa;            /* Local socket address         */
        struct usa      rsa;            /* Remote socket address        */
        bool_t          is_ssl;         /* Is socket SSL-ed             */
};

/*
 * Callback function, and where it is bound to
 */
struct callback {
        char            *uri_regex;     /* URI regex to handle          */
        mg_callback_t   func;           /* user callback                */
        bool_t          is_auth;        /* func is auth checker         */
        int             status_code;    /* error code to handle         */
        void            *user_data;     /* opaque user data             */
};

/*
 * Mongoose context
 */
struct mg_context {
        int             stop_flag;      /* Should we stop event loop    */
        SSL_CTX         *ssl_ctx;       /* SSL context                  */

        FILE            *access_log;    /* Opened access log            */
        FILE            *error_log;     /* Opened error log             */

        struct socket   listeners[MAX_LISTENING_SOCKETS];
        int             num_listeners;

        struct callback callbacks[MAX_CALLBACKS];
        int             num_callbacks;

        char            *options[NUM_OPTIONS];  /* Configured opions    */
        pthread_mutex_t opt_mutex[NUM_OPTIONS]; /* Option protector     */

        int             max_threads;    /* Maximum number of threads    */
        int             num_threads;    /* Number of threads            */
        int             num_idle;       /* Number of idle threads       */
        pthread_mutex_t thr_mutex;      /* Protects (max|num)_threads   */
        pthread_cond_t  thr_cond;
        pthread_mutex_t bind_mutex;     /* Protects bind operations     */

        struct socket   queue[20];      /* Accepted sockets             */
        int             sq_head;        /* Head of the socket queue     */
        int             sq_tail;        /* Tail of the socket queue     */
        pthread_cond_t  empty_cond;     /* Socket queue empty condvar   */
        pthread_cond_t  full_cond;      /* Socket queue full condvar    */

        mg_spcb_t       ssl_password_callback;
        mg_callback_t   log_callback;
};

/*
 * Client connection.
 */
struct mg_connection {
        struct mg_request_info  request_info;
        struct mg_context *ctx;         /* Mongoose context we belong to*/
        SSL             *ssl;           /* SSL descriptor               */
        struct socket   client;         /* Connected client             */
        time_t          birth_time;     /* Time connection was accepted */
        bool_t          free_post_data; /* post_data was malloc-ed      */
        bool_t          embedded_auth;  /* Used for authorization       */
        int64_t         num_bytes_sent; /* Total bytes sent to client   */
};

/*
 * Print error message to the opened error log stream.
 */
static void
cry(struct mg_connection *conn, const char *fmt, ...)
{
        char    buf[BUFSIZ];
        va_list ap;

        va_start(ap, fmt);
        (void) vsnprintf(buf, sizeof(buf), fmt, ap);
        conn->ctx->log_callback(conn, &conn->request_info, buf);
        va_end(ap);
}

/*
 * Return fake connection structure. Used for logging, if connection
 * is not applicable at the moment of logging.
 */
static struct mg_connection *
fc(struct mg_context *ctx)
{
        static struct mg_connection fake_connection;
        fake_connection.ctx = ctx;
        return (&fake_connection);
}

/*
 * If an embedded code does not intercept logging by calling
 * mg_set_log_callback(), this function is used for logging. It prints
 * stuff to the conn->error_log, which is stderr unless "error_log"
 * option was set.
 */
static void
builtin_error_log(struct mg_connection *conn,
                const struct mg_request_info *request_info, void *message)
{
        FILE    *fp;
        time_t  timestamp;

        fp = conn->ctx->error_log;
        flockfile(fp);

        timestamp = time(NULL);

        (void) fprintf(fp,
            "[%010lu] [error] [client %s] ",
            (unsigned long) timestamp,
            inet_ntoa(conn->client.rsa.u.sin.sin_addr));

        if (request_info->request_method != NULL)
                (void) fprintf(fp, "%s %s: ",
                    request_info->request_method,
                    request_info->uri);

        (void) fprintf(fp, "%s", (char *) message);

        fputc('\n', fp);

        funlockfile(fp);
}

const char *
mg_version(void)
{
        return (MONGOOSE_VERSION);
}

static void
mg_strlcpy(register char *dst, register const char *src, size_t n)
{
        for (; *src != '\0' && n > 1; n--)
                *dst++ = *src++;
        *dst = '\0';
}

static int
lowercase(const char *s)
{
        return (tolower(* (unsigned char *) s));
}

static int
mg_strncasecmp(const char *s1, const char *s2, size_t len)
{
        int     diff = 0;

        if (len > 0)
                do {
                        diff = lowercase(s1++) - lowercase(s2++);
                } while (diff == 0 && s1[-1] != '\0' && --len > 0);

        return (diff);
}

static int
mg_strcasecmp(const char *s1, const char *s2)
{
        int     diff;

        do {
                diff = lowercase(s1++) - lowercase(s2++);
        } while (diff == 0 && s1[-1] != '\0');

        return (diff);
}

static char *
mg_strndup(const char *ptr, size_t len)
{
        char    *p;

        if ((p = (char *) malloc(len + 1)) != NULL)
                mg_strlcpy(p, ptr, len + 1);

        return (p);

}

static char *
mg_strdup(const char *str)
{
        return (mg_strndup(str, strlen(str)));
}

/*
 * Like snprintf(), but never returns negative value, or the value
 * that is larger than a supplied buffer.
 * Thanks to Adam Zeldis to pointing snprintf()-caused vulnerability
 * in his audit report.
 */
static int
mg_vsnprintf(struct mg_connection *conn,
                char *buf, size_t buflen, const char *fmt, va_list ap)
{
        int     n;

        if (buflen == 0)
                return (0);

        n = vsnprintf(buf, buflen, fmt, ap);

        if (n < 0) {
                cry(conn, "vsnprintf error");
                n = 0;
        } else if (n >= (int) buflen) {
                cry(conn, "truncating vsnprintf buffer: [%.*s]",
                    n > 200 ? 200 : n, buf);
                n = (int) buflen - 1;
        }
        buf[n] = '\0';

        return (n);
}

static int
mg_snprintf(struct mg_connection *conn,
                char *buf, size_t buflen, const char *fmt, ...)
{
        va_list ap;
        int     n;

        va_start(ap, fmt);
        n = mg_vsnprintf(conn, buf, buflen, fmt, ap);
        va_end(ap);

        return (n);
}

/*
 * Convert string representing a boolean value to a boolean value
 */
static bool_t
is_true(const char *str)
{
        static const char       *trues[] = {"1", "yes", "true", "ja", NULL};
        int                     i;

        for (i = 0; trues[i] != NULL; i++)
                if (str != NULL && mg_strcasecmp(str, trues[i]) == 0)
                        return (TRUE);

        return (FALSE);
}

/*
 * Skip the characters until one of the delimiters characters found.
 * 0-terminate resulting word. Skip the rest of the delimiters if any.
 * Advance pointer to buffer to the next word. Return found 0-terminated word.
 */
static char *
skip(char **buf, const char *delimiters)
{
        char    *p, *begin_word, *end_word, *end_delimiters;

        begin_word = *buf;
        end_word = begin_word + strcspn(begin_word, delimiters);
        end_delimiters = end_word + strspn(end_word, delimiters);

        for (p = end_word; p < end_delimiters; p++)
                *p = '\0';

        *buf = end_delimiters;

        return (begin_word);
}

/*
 * Return HTTP header value, or NULL if not found.
 */
static const char *
get_header(const struct mg_request_info *ri, const char *name)
{
        int     i;

        for (i = 0; i < ri->num_headers; i++)
                if (!mg_strcasecmp(name, ri->http_headers[i].name))
                        return (ri->http_headers[i].value);

        return (NULL);
}

const char *
mg_get_header(const struct mg_connection *conn, const char *name)
{
        return (get_header(&conn->request_info, name));
}

/*
 * A helper function for traversing comma separated list of values.
 * It returns a list pointer shifted to the next value, of NULL if the end
 * of the list found.
 * Value is stored in val vector. If value has form "x=y", then eq_val
 * vector is initialized to point to the "y" part, and val vector length
 * is adjusted to point only to "x".
 */
static const char *
next_option(const char *list, struct vec *val, struct vec *eq_val)
{
        if (list == NULL || *list == '\0') {
                /* End of the list */
                list = NULL;
        } else {
                val->ptr = list;
                if ((list = strchr(val->ptr, ',')) != NULL) {
                        /* Comma found. Store length and shift the list ptr */
                        val->len = list - val->ptr;
                        list++;
                } else {
                        /* This value is the last one */
                        list = val->ptr + strlen(val->ptr);
                        val->len = list - val->ptr;
                }

                if (eq_val != NULL) {
                        /*
                         * Value has form "x=y", adjust pointers and lengths
                         * so that val points to "x", and eq_val points to "y".
                         */
                        eq_val->len = 0;
                        eq_val->ptr = memchr(val->ptr, '=', val->len);
                        if (eq_val->ptr != NULL) {
                                eq_val->ptr++;  /* Skip over '=' character */
                                eq_val->len = val->ptr + val->len - eq_val->ptr;
                                val->len = (eq_val->ptr - val->ptr) - 1;
                        }
                }
        }

        return (list);
}

#if !(defined(NO_CGI) && defined(NO_SSI))
/*
 * Verify that given file has certain extension
 */
static bool_t
match_extension(const char *path, const char *ext_list)
{
        struct vec      ext_vec;
        size_t          path_len;

        path_len = strlen(path);

        while ((ext_list = next_option(ext_list, &ext_vec, NULL)) != NULL)
                if (ext_vec.len < path_len &&
                    mg_strncasecmp(path + path_len - ext_vec.len,
                            ext_vec.ptr, ext_vec.len) == 0)
                        return (TRUE);

        return (FALSE);
}
#endif /* !(NO_CGI && NO_SSI) */

/*
 * Return TRUE if "uri" matches "regexp".
 * '*' in the regexp means zero or more characters.
 */
static bool_t
match_regex(const char *uri, const char *regexp)
{
        if (*regexp == '\0')
                return (*uri == '\0');

        if (*regexp == '*')
                do {
                        if (match_regex(uri, regexp + 1))
                                return (TRUE);
                } while (*uri++ != '\0');

        if (*uri != '\0' && *regexp == *uri)
                return (match_regex(uri + 1, regexp + 1));

        return (FALSE);
}

static const struct callback *
find_callback(struct mg_context *ctx, bool_t is_auth,
                const char *uri, int status_code)
{
        const struct callback   *cb, *found;
        int                     i;

        found = NULL;
        pthread_mutex_lock(&ctx->bind_mutex);
        for (i = 0; i < ctx->num_callbacks; i++) {
                cb = ctx->callbacks + i;
                if ((uri != NULL && cb->uri_regex != NULL &&
                    ((is_auth && cb->is_auth) || (!is_auth && !cb->is_auth)) &&
                    match_regex(uri, cb->uri_regex)) || (uri == NULL &&
                     (cb->status_code == 0 ||
                      cb->status_code == status_code))) {
                        found = cb;
                        break;
                }
        }
        pthread_mutex_unlock(&ctx->bind_mutex);

        return (found);
}

/*
 * For use by external application. This sets custom logging function.
 */
void
mg_set_log_callback(struct mg_context *ctx, mg_callback_t log_callback)
{
        /* If NULL is specified as a callback, revert back to the default */
        if (log_callback == NULL)
                ctx->log_callback = &builtin_error_log;
        else
                ctx->log_callback = log_callback;
}

/*
 * Send error message back to the client.
 */
static void
send_error(struct mg_connection *conn, int status, const char *reason,
                const char *fmt, ...)
{
        const struct callback   *cb;
        char            buf[BUFSIZ];
        va_list         ap;
        int             len;

        conn->request_info.status_code = status;

        /* If error handler is set, call it. Otherwise, send error message */
        if ((cb = find_callback(conn->ctx, FALSE, NULL, status)) != NULL) {
                cb->func(conn, &conn->request_info, cb->user_data);
        } else {
                buf[0] = '\0';
                len = 0;

                /* Errors 1xx, 204 and 304 MUST NOT send a body */
                if (status > 199 && status != 204 && status != 304) {
                        len = mg_snprintf(conn, buf, sizeof(buf),
                            "Error %d: %s\n", status, reason);
                        cry(conn, "%s", buf);

                        va_start(ap, fmt);
                        len += mg_vsnprintf(conn, buf + len, sizeof(buf) - len,
                            fmt, ap);
                        va_end(ap);
                        conn->num_bytes_sent = len;
                }

                (void) mg_printf(conn,
                    "HTTP/1.1 %d %s\r\n"
                    "Content-Type: text/plain\r\n"
                    "Content-Length: %d\r\n"
                    "Connection: close\r\n"
                    "\r\n%s", status, reason, len, buf);
        }
}

#ifdef _WIN32
static int
pthread_mutex_init(pthread_mutex_t *mutex, void *unused)
{
        unused = NULL;
        *mutex = CreateMutex(NULL, FALSE, NULL);
        return (*mutex == NULL ? -1 : 0);
}

static int
pthread_mutex_destroy(pthread_mutex_t *mutex)
{
        return (CloseHandle(*mutex) == 0 ? -1 : 0);
}

static int
pthread_mutex_lock(pthread_mutex_t *mutex)
{
        return (WaitForSingleObject(*mutex, INFINITE) == WAIT_OBJECT_0? 0 : -1);
}

static int
pthread_mutex_unlock(pthread_mutex_t *mutex)
{
        return (ReleaseMutex(*mutex) == 0 ? -1 : 0);
}

static int
pthread_cond_init(pthread_cond_t *cv, const void *unused)
{
        unused = NULL;
        *cv = CreateEvent(NULL, FALSE, FALSE, NULL);
        return (*cv == NULL ? -1 : 0);
}

static int
pthread_cond_timedwait(pthread_cond_t *cv, pthread_mutex_t *mutex,
        const struct timespec *ts)
{
        DWORD   status;
        DWORD   msec = INFINITE;
        time_t  now;
        
        if (ts != NULL) {
                now = time(NULL);
                msec = 1000 * (now > ts->tv_sec ? 0 : ts->tv_sec - now);
        }

        (void) ReleaseMutex(*mutex);
        status = WaitForSingleObject(*cv, msec);
        (void) WaitForSingleObject(*mutex, INFINITE);
        
        return (status == WAIT_OBJECT_0 ? 0 : -1);
}

static int
pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
{
        return (pthread_cond_timedwait(cv, mutex, NULL));
}

static int
pthread_cond_signal(pthread_cond_t *cv)
{
        return (SetEvent(*cv) == 0 ? -1 : 0);
}

static int
pthread_cond_destroy(pthread_cond_t *cv)
{
        return (CloseHandle(*cv) == 0 ? -1 : 0);
}

static pthread_t
pthread_self(void)
{
        return (GetCurrentThreadId());
}

/*
 * Change all slashes to backslashes. It is Windows.
 */
static void
fix_directory_separators(char *path)
{
        int     i;

        for (i = 0; path[i] != '\0'; i++) {
                if (path[i] == '/')
                        path[i] = '\\';
                /* i > 0 check is to preserve UNC paths, \\server\file.txt */
                if (path[i] == '\\' && i > 0)
                        while (path[i + 1] == '\\' || path[i + 1] == '/')
                                (void) memmove(path + i + 1,
                                    path + i + 2, strlen(path + i + 1));
        }
}

/*
 * Encode 'path' which is assumed UTF-8 string, into UNICODE string.
 * wbuf and wbuf_len is a target buffer and its length.
 */
static void
to_unicode(const char *path, wchar_t *wbuf, size_t wbuf_len)
{
        char    buf[FILENAME_MAX], *p;

        mg_strlcpy(buf, path, sizeof(buf));
        fix_directory_separators(buf);

        /* Point p to the end of the file name */
        p = buf + strlen(buf) - 1;

        /* Trim trailing backslash character */
        while (p > buf && *p == '\\' && p[-1] != ':')
                *p-- = '\0';

        /*
         * Protect from CGI code disclosure.
         * This is very nasty hole. Windows happily opens files with
         * some garbage in the end of file name. So fopen("a.cgi    ", "r")
         * actually opens "a.cgi", and does not return an error!
         */
        if (*p == 0x20 ||               /* No space at the end */
            (*p == 0x2e && p > buf) ||  /* No '.' but allow '.' as full path */
            *p == 0x2b ||               /* No '+' */
            (*p & ~0x7f)) {             /* And generally no non-ascii chars */
                (void) fprintf(stderr, "Rejecting suspicious path: [%s]", buf);
                buf[0] = '\0';
        }

        (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int) wbuf_len);
}

#if defined(_WIN32_WCE)

static time_t
time(time_t *ptime)
{
        time_t          t;
        SYSTEMTIME      st;
        FILETIME        ft;

        GetSystemTime(&st);
        SystemTimeToFileTime(&st, &ft);
        t = SYS2UNIX_TIME(ft.dwLowDateTime, ft.dwHighDateTime);

        if (ptime != NULL)
                *ptime = t;

        return (t);
}

static time_t
mktime(struct tm *ptm)
{
        SYSTEMTIME      st;
        FILETIME        ft, lft;

        st.wYear = ptm->tm_year + 1900;
        st.wMonth = ptm->tm_mon + 1;
        st.wDay = ptm->tm_mday;
        st.wHour = ptm->tm_hour;
        st.wMinute = ptm->tm_min;
        st.wSecond = ptm->tm_sec;
        st.wMilliseconds = 0;

        SystemTimeToFileTime(&st, &ft);
        LocalFileTimeToFileTime(&ft, &lft);
        return (time_t)((MAKEUQUAD(lft.dwLowDateTime, lft.dwHighDateTime) -
            EPOCH_DIFF) / RATE_DIFF);
}

static struct tm *
localtime(const time_t *ptime, struct tm *ptm)
{
        int64_t t = ((int64_t)*ptime) * RATE_DIFF + EPOCH_DIFF;
        FILETIME        ft, lft;
        SYSTEMTIME      st;
        TIME_ZONE_INFORMATION   tzinfo;

        if (ptm == NULL)
                return NULL;

        * (int64_t *) &ft = t;
        FileTimeToLocalFileTime(&ft, &lft);
        FileTimeToSystemTime(&lft, &st);
        ptm->tm_year = st.wYear - 1900;
        ptm->tm_mon = st.wMonth - 1;
        ptm->tm_wday = st.wDayOfWeek;
        ptm->tm_mday = st.wDay;
        ptm->tm_hour = st.wHour;
        ptm->tm_min = st.wMinute;
        ptm->tm_sec = st.wSecond;
        ptm->tm_yday = 0; // hope nobody uses this
        ptm->tm_isdst = ((GetTimeZoneInformation(&tzinfo) ==
            TIME_ZONE_ID_DAYLIGHT) ? 1 : 0);

        return ptm;
}

static size_t
strftime(char *dst, size_t dst_size, const char *fmt, const struct tm *tm)
{
        (void) snprintf(dst, dst_size, "implement strftime() for WinCE");
        return (0);
}       
#endif

static int
mg_rename(const char* oldname, const char* newname)
{
        wchar_t woldbuf[FILENAME_MAX];
        wchar_t wnewbuf[FILENAME_MAX];

        to_unicode(oldname, woldbuf, ARRAY_SIZE(woldbuf));
        to_unicode(newname, wnewbuf, ARRAY_SIZE(wnewbuf));

        return (MoveFileW(woldbuf, wnewbuf) ? 0 : -1);
}


static FILE *
mg_fopen(const char *path, const char *mode)
{
        wchar_t wbuf[FILENAME_MAX], wmode[20];

        to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
        MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, ARRAY_SIZE(wmode));

        return (_wfopen(wbuf, wmode));
}

static int
mg_stat(const char *path, struct mgstat *stp)
{
        int                             ok = -1; /* Error */
        wchar_t                         wbuf[FILENAME_MAX];
        WIN32_FILE_ATTRIBUTE_DATA       info;

        to_unicode(path, wbuf, ARRAY_SIZE(wbuf));

        if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
                stp->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
                stp->mtime = SYS2UNIX_TIME(info.ftLastWriteTime.dwLowDateTime,
                    info.ftLastWriteTime.dwHighDateTime);
                stp->is_directory =
                    info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
                ok = 0;  /* Success */
        }

        return (ok);
}

static int
mg_remove(const char *path)
{
        wchar_t wbuf[FILENAME_MAX];

        to_unicode(path, wbuf, ARRAY_SIZE(wbuf));

        return (DeleteFileW(wbuf) ? 0 : -1);
}

static int
mg_mkdir(const char *path, int mode)
{
        char    buf[FILENAME_MAX];
        wchar_t wbuf[FILENAME_MAX];

        mode = 0; /* Unused */
        mg_strlcpy(buf, path, sizeof(buf));
        fix_directory_separators(buf);

        (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, sizeof(wbuf));

        return (CreateDirectoryW(wbuf, NULL) ? 0 : -1);
}

/*
 * Implementation of POSIX opendir/closedir/readdir for Windows.
 */
static DIR *
opendir(const char *name)
{
        DIR     *dir = NULL;
        wchar_t wpath[FILENAME_MAX];
        DWORD attrs;

        if (name == NULL) {
                SetLastError(ERROR_BAD_ARGUMENTS);
        } else if ((dir = (DIR *) malloc(sizeof(*dir))) == NULL) {
                SetLastError(ERROR_NOT_ENOUGH_MEMORY);
        } else {
                to_unicode(name, wpath, ARRAY_SIZE(wpath));
                attrs = GetFileAttributesW(wpath);
                if (attrs != 0xFFFFFFFF &&
                    ((attrs & FILE_ATTRIBUTE_DIRECTORY) == FILE_ATTRIBUTE_DIRECTORY)) {
                        (void) wcscat(wpath, L"\\*");
                        dir->handle = FindFirstFileW(wpath, &dir->info);
                        dir->result.d_name[0] = '\0';
                } else {
                        free(dir);
                        dir = NULL;
                }
        }

        return (dir);
}

static int
closedir(DIR *dir)
{
        int result = 0;

        if (dir != NULL) {
                if (dir->handle != INVALID_HANDLE_VALUE)
                        result = FindClose(dir->handle) ? 0 : -1;

                free(dir);
        } else {
                result = -1;
                SetLastError(ERROR_BAD_ARGUMENTS);
        }

        return (result);
}

struct dirent *
readdir(DIR *dir)
{
        struct dirent *result = 0;

        if (dir) {
                if (dir->handle != INVALID_HANDLE_VALUE) {
                        result = &dir->result;
                        (void) WideCharToMultiByte(CP_UTF8, 0,
                            dir->info.cFileName, -1, result->d_name,
                            sizeof(result->d_name), NULL, NULL);

                        if (!FindNextFileW(dir->handle, &dir->info)) {
                                (void) FindClose(dir->handle);
                                dir->handle = INVALID_HANDLE_VALUE;
                        }

                } else {
                        SetLastError(ERROR_FILE_NOT_FOUND);
                }
        } else {
                SetLastError(ERROR_BAD_ARGUMENTS);
        }

        return (result);
}

#define set_close_on_exec(fd)   /* No FD_CLOEXEC on Windows */

static int
start_thread(struct mg_context *ctx, mg_thread_func_t func, void *param)
{
        HANDLE  hThread;

        ctx = NULL;     /* Unused */
        
        hThread = CreateThread(NULL, 0,
            (LPTHREAD_START_ROUTINE) func, param, 0, NULL);

        if (hThread != NULL)
                (void) CloseHandle(hThread);

        return (hThread == NULL ? -1 : 0);
}

static HANDLE
dlopen(const char *dll_name, int flags)
{
        wchar_t wbuf[FILENAME_MAX];

        flags = 0; /* Unused */
        to_unicode(dll_name, wbuf, ARRAY_SIZE(wbuf));

        return (LoadLibraryW(wbuf));
}

#if !defined(NO_CGI)
static int
kill(pid_t pid, int sig_num)
{
        (void) TerminateProcess(pid, sig_num);
        (void) CloseHandle(pid);
        return (0);
}

static pid_t
spawn_process(struct mg_connection *conn, const char *prog, char *envblk,
                char *envp[], int fd_stdin, int fd_stdout, const char *dir)
{
        HANDLE  me;
        char    *p, *interp, cmdline[FILENAME_MAX], line[FILENAME_MAX];
        FILE    *fp;
        STARTUPINFOA            si;
        PROCESS_INFORMATION     pi;

        envp = NULL; /* Unused */

        (void) memset(&si, 0, sizeof(si));
        (void) memset(&pi, 0, sizeof(pi));

        /* XXX redirect CGI errors to the error log file */
        si.cb           = sizeof(si);
        si.dwFlags      = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
        si.wShowWindow  = SW_HIDE;

        me = GetCurrentProcess();
        (void) DuplicateHandle(me, (HANDLE) _get_osfhandle(fd_stdin), me,
            &si.hStdInput, 0, TRUE, DUPLICATE_SAME_ACCESS);
        (void) DuplicateHandle(me, (HANDLE) _get_osfhandle(fd_stdout), me,
            &si.hStdOutput, 0, TRUE, DUPLICATE_SAME_ACCESS);

        /* If CGI file is a script, try to read the interpreter line */
        interp = conn->ctx->options[OPT_CGI_INTERPRETER];
        if (interp == NULL) {
                line[2] = '\0';
                (void) mg_snprintf(conn, cmdline, sizeof(cmdline), "%s%c%s",
                    dir, DIRSEP, prog);
                if ((fp = fopen(cmdline, "r")) != NULL) {
                        (void) fgets(line, sizeof(line), fp);
                        if (memcmp(line, "#!", 2) != 0)
                                line[2] = '\0';
                        /* Trim whitespaces from interpreter name */
                        for (p = &line[strlen(line) - 1]; p > line &&
                            isspace(*p); p--)
                                *p = '\0';
                        (void) fclose(fp);
                }
                interp = line + 2;
        }

        if ((p = (char *) strrchr(prog, '/')) != NULL)
                prog = p + 1;

        (void) mg_snprintf(conn, cmdline, sizeof(cmdline), "%s%s%s",
            interp, interp[0] == '\0' ? "" : " ", prog);

        (void) mg_snprintf(conn, line, sizeof(line), "%s", dir);
        fix_directory_separators(line);

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: Running [%s]", __func__, cmdline));
        if (CreateProcessA(NULL, cmdline, NULL, NULL, TRUE,
            CREATE_NEW_PROCESS_GROUP, envblk, line, &si, &pi) == 0) {
                cry(conn, "%s: CreateProcess(%s): %d",
                    __func__, cmdline, ERRNO);
                pi.hProcess = (pid_t) -1;
        } else {
                (void) close(fd_stdin);
                (void) close(fd_stdout);
        }

        (void) CloseHandle(si.hStdOutput);
        (void) CloseHandle(si.hStdInput);
        (void) CloseHandle(pi.hThread);

        return ((pid_t) pi.hProcess);
}

static int
pipe(int *fds)
{
        return (_pipe(fds, BUFSIZ, _O_BINARY));
}
#endif /* !NO_CGI */

static int
set_non_blocking_mode(struct mg_connection *conn, SOCKET sock)
{
        unsigned long   on = 1;

        conn = NULL; /* unused */
        return (ioctlsocket(sock, FIONBIO, &on));
}

#else

static int
mg_stat(const char *path, struct mgstat *stp)
{
        struct stat     st;
        int             ok;

        if (stat(path, &st) == 0) {
                ok = 0;
                stp->size = st.st_size;
                stp->mtime = st.st_mtime;
                stp->is_directory = S_ISDIR(st.st_mode);
        } else {
                ok = -1;
        }

        return (ok);
}

static void
set_close_on_exec(int fd)
{
        (void) fcntl(fd, F_SETFD, FD_CLOEXEC);
}

static int
start_thread(struct mg_context *ctx, mg_thread_func_t func, void *param)
{
        pthread_t       thread_id;
        pthread_attr_t  attr;
        int             retval;

        (void) pthread_attr_init(&attr);
        (void) pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

        if ((retval = pthread_create(&thread_id, &attr, func, param)) != 0)
                cry(fc(ctx), "%s: %s", __func__, strerror(retval));

        return (retval);
}

#ifndef NO_CGI
static pid_t
spawn_process(struct mg_connection *conn, const char *prog, char *envblk,
                char *envp[], int fd_stdin, int fd_stdout, const char *dir)
{
        pid_t           pid;
        const char      *interp;

        envblk = NULL;  /* unused */

        if ((pid = fork()) == -1) {
                /* Parent */
                send_error(conn, 500, http_500_error,
                    "fork(): %s", strerror(ERRNO));
        } else if (pid == 0) {
                /* Child */
                if (chdir(dir) != 0) {
                        cry(conn, "%s: chdir(%s): %s",
                            __func__, dir, strerror(ERRNO));
                } else if (dup2(fd_stdin, 0) == -1) {
                        cry(conn, "%s: dup2(stdin, %d): %s",
                            __func__, fd_stdin, strerror(ERRNO));
                } else if (dup2(fd_stdout, 1) == -1) {
                        cry(conn, "%s: dup2(stdout, %d): %s",
                            __func__, fd_stdout, strerror(ERRNO));
                } else {
                        /* If error file is specified, send errors there */
                        if (conn->ctx->error_log != NULL)
                                (void) dup2(fileno(conn->ctx->error_log), 2);

                        (void) close(fd_stdin);
                        (void) close(fd_stdout);

                        /* Execute CGI program */
                        interp = conn->ctx->options[OPT_CGI_INTERPRETER];
                        if (interp == NULL) {
                                (void) execle(prog, prog, NULL, envp);
                                cry(conn, "%s: execle(%s): %s",
                                    __func__, prog, strerror(ERRNO));
                        } else {
                                (void) execle(interp, interp, prog, NULL, envp);
                                cry(conn, "%s: execle(%s %s): %s",
                                    __func__, interp, prog, strerror(ERRNO));
                        }
                }
                exit(EXIT_FAILURE);
        } else {
                /* Parent. Close stdio descriptors */
                (void) close(fd_stdin);
                (void) close(fd_stdout);
        }

        return (pid);
}
#endif /* !NO_CGI */

static int
set_non_blocking_mode(struct mg_connection *conn, SOCKET sock)
{
        int     flags, ok = -1;

        if ((flags = fcntl(sock, F_GETFL, 0)) == -1) {
                cry(conn, "%s: fcntl(F_GETFL): %d", __func__, ERRNO);
        } else if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) != 0) {
                cry(conn, "%s: fcntl(F_SETFL): %d", __func__, ERRNO);
        } else {
                ok = 0; /* Success */
        }

        return (ok);
}
#endif /* _WIN32 */

static void
lock_option(struct mg_context *ctx, int opt_index)
{
        if (pthread_mutex_lock(&ctx->opt_mutex[opt_index]) != 0)
                cry(fc(ctx), "pthread_mutex_lock: %s", strerror(ERRNO));
}

static void
unlock_option(struct mg_context *ctx, int opt_index)
{
        if (pthread_mutex_unlock(&ctx->opt_mutex[opt_index]) != 0)
                cry(fc(ctx), "pthread_mutex_unlock: %s", strerror(ERRNO));
}

/*
 * Write data to the IO channel - opened file descriptor, socket or SSL
 * descriptor. Return number of bytes written.
 */
static int64_t
push(FILE *fp, SOCKET sock, SSL *ssl, const char *buf, int64_t len)
{
        int64_t sent;
        int     n, k;

        sent = 0;
        while (sent < len) {

                /* How many bytes we send in this iteration */
                k = len - sent > INT_MAX ? INT_MAX : (int) (len - sent);

                if (ssl != NULL) {
                        n = SSL_write(ssl, buf + sent, k);
                } else if (fp != NULL) {
                        n = fwrite(buf + sent, 1, k, fp);
                        if (ferror(fp))
                                n = -1;
                } else {
                        n = send(sock, buf + sent, k, 0);
                }

                if (n < 0)
                        break;

                sent += n;
        }

        return (sent);
}

/*
 * Read from IO channel - opened file descriptor, socket, or SSL descriptor.
 * Return number of bytes read.
 */
static int
pull(FILE *fp, SOCKET sock, SSL *ssl, char *buf, int len)
{
        int     nread;

        if (ssl != NULL) {
                nread = SSL_read(ssl, buf, len);
        } else if (fp != NULL) {
                nread = fread(buf, 1, (size_t) len, fp);
                if (ferror(fp))
                        nread = -1;
        } else {
                nread = recv(sock, buf, (size_t) len, 0);
        }

        return (nread);
}

int
mg_write(struct mg_connection *conn, const void *buf, int len)
{
        assert(len >= 0);
        return ((int) push(NULL, conn->client.sock, conn->ssl,
                                (const char *) buf, (int64_t) len));
}

int
mg_printf(struct mg_connection *conn, const char *fmt, ...)
{
        char    buf[MAX_REQUEST_SIZE];
        int     len;
        va_list ap;

        va_start(ap, fmt);
        len = mg_vsnprintf(conn, buf, sizeof(buf), fmt, ap);
        va_end(ap);

        return (mg_write(conn, buf, len));
}

/*
 * Return content length of the request, or -1 constant if
 * Content-Length header is not set.
 */
static int64_t
get_content_length(const struct mg_connection *conn)
{
        const char *cl = mg_get_header(conn, "Content-Length");
        return (cl == NULL ? -1 : strtoll(cl, NULL, 10));
}

/*
 * URL-decode input buffer into destination buffer.
 * 0-terminate the destination buffer. Return the length of decoded data.
 * form-url-encoded data differs from URI encoding in a way that it
 * uses '+' as character for space, see RFC 1866 section 8.2.1
 * http://ftp.ics.uci.edu/pub/ietf/html/rfc1866.txt
 */
static size_t
url_decode(const char *src, size_t src_len, char *dst, size_t dst_len,
                bool_t is_form_url_encoded)
{
        size_t  i, j;
        int     a, b;
#define HEXTOI(x)       (isdigit(x) ? x - '0' : x - 'W')

        for (i = j = 0; i < src_len && j < dst_len - 1; i++, j++) {
                if (src[i] == '%' &&
                    isxdigit(* (unsigned char *) (src + i + 1)) &&
                    isxdigit(* (unsigned char *) (src + i + 2))) {
                        a = tolower(* (unsigned char *) (src + i + 1));
                        b = tolower(* (unsigned char *) (src + i + 2));
                        dst[j] = ((HEXTOI(a) << 4) | HEXTOI(b)) & 0xff;
                        i += 2;
                } else if (is_form_url_encoded && src[i] == '+') {
                        dst[j] = ' ';
                } else {
                        dst[j] = src[i];
                }
        }

        dst[j] = '\0';  /* Null-terminate the destination */

        return (j);
}

/*
 * Search for a form variable in a given buffer.
 * Semantic is the same as for mg_get_var().
 */
static char *
get_var(const char *name, const char *buf, size_t buf_len)
{
        const char      *p, *e, *s;
        char            *val;
        size_t          var_len, len;

        var_len = strlen(name);
        e = buf + buf_len;
        val = NULL;

        /* buf is "var1=val1&var2=val2...". Find variable first */
        for (p = buf; p + var_len < e; p++)
                if ((p == buf || p[-1] == '&') && p[var_len] == '=' &&
                    !mg_strncasecmp(name, p, var_len)) {

                        /* Point p to variable value */
                        p += var_len + 1;

                        /* Point s to the end of the value */
                        s = (const char *) memchr(p, '&', e - p);
                        if (s == NULL)
                                s = e;

                        /* Try to allocate the buffer */
                        len = s - p;
                        if ((val = (char *) malloc(len + 1)) != NULL)
                                (void) url_decode(p, len, val, len + 1, TRUE);
                        break;
                }

        return (val);
}

/*
 * Free the pointer returned by mg_get_var(). This is needed for languages
 * like python, to have an ability to free allocated data without
 * loading C runtime library and calling free().
 */
void
mg_free(char *data)
{
        free(data);
}

/*
 * Return form data variable.
 * It can be specified in query string, or in the POST data.
 * Return NULL if the variable not found, or allocated 0-terminated value.
 * It is caller's responsibility to free the returned value.
 */
char *
mg_get_var(const struct mg_connection *conn, const char *name)
{
        const struct mg_request_info    *ri = &conn->request_info;
        char                            *v1, *v2;

        v1 = v2 = NULL;

        /* Look in both query_string and POST data */
        if (ri->query_string != NULL)
                v1 = get_var(name, ri->query_string, strlen(ri->query_string));
        if (ri->post_data_len > 0)
                v2 = get_var(name, ri->post_data, ri->post_data_len);

        /* If they both have queried variable, POST data wins */
        if (v1 != NULL && v2 != NULL)
                free(v1);

        return (v2 == NULL ? v1 : v2);
}

/*
 * Transform URI to the file name.
 */
static void
convert_uri_to_file_name(struct mg_connection *conn, const char *uri,
                char *buf, size_t buf_len)
{
        struct mg_context       *ctx = conn->ctx;
        struct vec              uri_vec, path_vec;
        const char              *list;

        lock_option(ctx, OPT_ROOT);
        mg_snprintf(conn, buf, buf_len, "%s%s", ctx->options[OPT_ROOT], uri);
        unlock_option(ctx, OPT_ROOT);

        /* If requested URI has aliased prefix, use alternate root */
        lock_option(ctx, OPT_ALIASES);
        list = ctx->options[OPT_ALIASES];

        while ((list = next_option(list, &uri_vec, &path_vec)) != NULL) {
                if (memcmp(uri, uri_vec.ptr, uri_vec.len) == 0) {
                        (void) mg_snprintf(conn, buf, buf_len, "%.*s%s",
                            path_vec.len, path_vec.ptr, uri + uri_vec.len);
                        break;
                }
        }
        unlock_option(ctx, OPT_ALIASES);

#ifdef _WIN32
        fix_directory_separators(buf);
#endif /* _WIN32 */

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: [%s] -> [%s]", __func__, uri, buf));
}

/*
 * Setup listening socket on given address, return socket.
 * Address format: [local_ip_address:]port_number
 */
static SOCKET
mg_open_listening_port(struct mg_context *ctx, const char *str, struct usa *usa)
{
        SOCKET          sock;
        int             on = 1, a, b, c, d, port;

        /* MacOS needs that. If we do not zero it, bind() will fail. */
        (void) memset(usa, 0, sizeof(*usa));

        if (sscanf(str, "%d.%d.%d.%d:%d", &a, &b, &c, &d, &port) == 5) {
                /* IP address to bind to is specified */
                usa->u.sin.sin_addr.s_addr =
                    htonl(((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8) | (uint32_t)d);
        } else if (sscanf(str, "%d", &port) == 1) {
                /* Only port number is specified. Bind to all addresses */
                usa->u.sin.sin_addr.s_addr = htonl(INADDR_ANY);
        } else {
                return (INVALID_SOCKET);
        }

        usa->len                        = sizeof(usa->u.sin);
        usa->u.sin.sin_family           = AF_INET;
        usa->u.sin.sin_port             = htons((uint16_t) port);

        if ((sock = socket(PF_INET, SOCK_STREAM, 6)) != INVALID_SOCKET &&
            setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
            (char *) &on, sizeof(on)) == 0 &&
            bind(sock, &usa->u.sa, usa->len) == 0 &&
            listen(sock, 20) == 0) {
                /* Success */
                set_close_on_exec(sock);
        } else {
                /* Error */
                cry(fc(ctx), "%s(%d): %s", __func__, port, strerror(ERRNO));
                if (sock != INVALID_SOCKET)
                        (void) closesocket(sock);
                sock = INVALID_SOCKET;
        }

        return (sock);
}

/*
 * Check whether full request is buffered. Return:
 *   -1         if request is malformed
 *    0         if request is not yet fully buffered
 *   >0         actual request length, including last \r\n\r\n
 */
static int
get_request_len(const char *buf, size_t buflen)
{
        const char      *s, *e;
        int             len = 0;

        for (s = buf, e = s + buflen - 1; len <= 0 && s < e; s++)
                /* Control characters are not allowed but >=128 is. */
                if (!isprint(* (unsigned char *) s) && *s != '\r' &&
                    *s != '\n' && * (unsigned char *) s < 128)
                        len = -1;
                else if (s[0] == '\n' && s[1] == '\n')
                        len = (int) (s - buf) + 2;
                else if (s[0] == '\n' && &s[1] < e &&
                    s[1] == '\r' && s[2] == '\n')
                        len = (int) (s - buf) + 3;

        return (len);
}

/*
 * Convert month to the month number. Return -1 on error, or month number
 */
static int
montoi(const char *s)
{
        size_t  i;

        for (i = 0; i < sizeof(month_names) / sizeof(month_names[0]); i++)
                if (!strcmp(s, month_names[i]))
                        return ((int) i);

        return (-1);
}

/*
 * Parse date-time string, and return the corresponding time_t value
 */
static time_t
date_to_epoch(const char *s)
{
        time_t          current_time;
        struct tm       tm, *tmp;
        char            mon[32];
        int             sec, min, hour, mday, month, year;

        (void) memset(&tm, 0, sizeof(tm));
        sec = min = hour = mday = month = year = 0;

        if (((sscanf(s, "%d/%3s/%d %d:%d:%d",
            &mday, mon, &year, &hour, &min, &sec) == 6) ||
            (sscanf(s, "%d %3s %d %d:%d:%d",
            &mday, mon, &year, &hour, &min, &sec) == 6) ||
            (sscanf(s, "%*3s, %d %3s %d %d:%d:%d",
            &mday, mon, &year, &hour, &min, &sec) == 6) ||
            (sscanf(s, "%d-%3s-%d %d:%d:%d",
            &mday, mon, &year, &hour, &min, &sec) == 6)) &&
            (month = montoi(mon)) != -1) {
                tm.tm_mday      = mday;
                tm.tm_mon       = month;
                tm.tm_year      = year;
                tm.tm_hour      = hour;
                tm.tm_min       = min;
                tm.tm_sec       = sec;
        }

        if (tm.tm_year > 1900)
                tm.tm_year -= 1900;
        else if (tm.tm_year < 70)
                tm.tm_year += 100;

        /* Set Daylight Saving Time field */
        current_time = time(NULL);
        tmp = localtime(&current_time);
        tm.tm_isdst = tmp->tm_isdst;

        return (mktime(&tm));
}

/*
 * Protect against directory disclosure attack by removing '..',
 * excessive '/' and '\' characters
 */
static void
remove_double_dots_and_double_slashes(char *s)
{
        char    *p = s;

        while (*s != '\0') {
                *p++ = *s++;
                if (s[-1] == '/' || s[-1] == '\\') {
                        /* Skip all following slashes and backslashes */
                        while (*s == '/' || *s == '\\')
                                s++;

                        /* Skip all double-dots */
                        while (*s == '.' && s[1] == '.')
                                s += 2;
                }
        }
        *p = '\0';
}

/*
 * Built-in mime types
 */
static const struct {
        const char      *extension;
        size_t          ext_len;
        const char      *mime_type;
        size_t          mime_type_len;
} mime_types[] = {
        {".html",       5,      "text/html",                    9},
        {".htm",        4,      "text/html",                    9},
        {".shtm",       5,      "text/html",                    9},
        {".shtml",      6,      "text/html",                    9},
        {".css",        4,      "text/css",                     8},
        {".js",         3,      "application/x-javascript",     24},
        {".ico",        4,      "image/x-icon",                 12},
        {".gif",        4,      "image/gif",                    9},
        {".jpg",        4,      "image/jpeg",                   10},
        {".jpeg",       5,      "image/jpeg",                   10},
        {".png",        4,      "image/png",                    9},
        {".svg",        4,      "image/svg+xml",                13},
        {".torrent",    8,      "application/x-bittorrent",     24},
        {".wav",        4,      "audio/x-wav",                  11},
        {".mp3",        4,      "audio/x-mp3",                  11},
        {".mid",        4,      "audio/mid",                    9},
        {".m3u",        4,      "audio/x-mpegurl",              15},
        {".ram",        4,      "audio/x-pn-realaudio",         20},
        {".xml",        4,      "text/xml",                     8},
        {".xslt",       5,      "application/xml",              15},
        {".ra",         3,      "audio/x-pn-realaudio",         20},
        {".doc",        4,      "application/msword",           19},
        {".exe",        4,      "application/octet-stream",     24},
        {".zip",        4,      "application/x-zip-compressed", 28},
        {".xls",        4,      "application/excel",            17},
        {".tgz",        4,      "application/x-tar-gz",         20},
        {".tar",        4,      "application/x-tar",            17},
        {".gz",         3,      "application/x-gunzip",         20},
        {".arj",        4,      "application/x-arj-compressed", 28},
        {".rar",        4,      "application/x-arj-compressed", 28},
        {".rtf",        4,      "application/rtf",              15},
        {".pdf",        4,      "application/pdf",              15},
        {".swf",        4,      "application/x-shockwave-flash",29},
        {".mpg",        4,      "video/mpeg",                   10},
        {".mpeg",       5,      "video/mpeg",                   10},
        {".asf",        4,      "video/x-ms-asf",               14},
        {".avi",        4,      "video/x-msvideo",              15},
        {".bmp",        4,      "image/bmp",                    9},
        {NULL,          0,      NULL,                           0}
};

/*
 * Look at the "path" extension and figure what mime type it has.
 * Store mime type in the vector.
 */
static void
get_mime_type(struct mg_context *ctx, const char *path, struct vec *vec)
{
        struct vec      ext_vec, mime_vec;
        const char      *list, *ext;
        size_t          i, path_len;

        path_len = strlen(path);

        /*
         * Scan user-defined mime types first, in case user wants to
         * override default mime types.
         */
        lock_option(ctx, OPT_MIME_TYPES);
        list = ctx->options[OPT_MIME_TYPES];
        while ((list = next_option(list, &ext_vec, &mime_vec)) != NULL) {
                /* ext now points to the path suffix */
                ext = path + path_len - ext_vec.len;
                if (mg_strncasecmp(ext, ext_vec.ptr, ext_vec.len) == 0) {
                        *vec = mime_vec;
                        unlock_option(ctx, OPT_MIME_TYPES);
                        return;
                }
        }
        unlock_option(ctx, OPT_MIME_TYPES);

        /* Now scan built-in mime types */
        for (i = 0; mime_types[i].extension != NULL; i++) {
                ext = path + (path_len - mime_types[i].ext_len);
                if (path_len > mime_types[i].ext_len &&
                    mg_strcasecmp(ext, mime_types[i].extension) == 0) {
                        vec->ptr = mime_types[i].mime_type;
                        vec->len = mime_types[i].mime_type_len;
                        return;
                }
        }

        /* Nothing found. Fall back to text/plain */
        vec->ptr = "text/plain";
        vec->len = 10;
}

#ifndef HAVE_MD5
typedef struct MD5Context {
        uint32_t        buf[4];
        uint32_t        bits[2];
        unsigned char   in[64];
} MD5_CTX;

#if __BYTE_ORDER == 1234
#define byteReverse(buf, len)   /* Nothing */
#else
/*
 * Note: this code is harmless on little-endian machines.
 */
static void
byteReverse(unsigned char *buf, unsigned longs)
{
        uint32_t t;
        do {
                t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
                        ((unsigned) buf[1] << 8 | buf[0]);
                *(uint32_t *) buf = t;
                buf += 4;
        } while (--longs);
}
#endif /* __BYTE_ORDER */

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
static void
MD5Init(MD5_CTX *ctx)
{
        ctx->buf[0] = 0x67452301;
        ctx->buf[1] = 0xefcdab89;
        ctx->buf[2] = 0x98badcfe;
        ctx->buf[3] = 0x10325476;

        ctx->bits[0] = 0;
        ctx->bits[1] = 0;
}

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void
MD5Transform(uint32_t buf[4], uint32_t const in[16])
{
        register uint32_t a, b, c, d;

        a = buf[0];
        b = buf[1];
        c = buf[2];
        d = buf[3];

        MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
        MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
        MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
        MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
        MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
        MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
        MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
        MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
        MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
        MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
        MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
        MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
        MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
        MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
        MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
        MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

        MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
        MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
        MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
        MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
        MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
        MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
        MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
        MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
        MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
        MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
        MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
        MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
        MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
        MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
        MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
        MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

        MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
        MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
        MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
        MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
        MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
        MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
        MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
        MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
        MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
        MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
        MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
        MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
        MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
        MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
        MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
        MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

        MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
        MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
        MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
        MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
        MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
        MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
        MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
        MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
        MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
        MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
        MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
        MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
        MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
        MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
        MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

        buf[0] += a;
        buf[1] += b;
        buf[2] += c;
        buf[3] += d;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
static void
MD5Update(MD5_CTX *ctx, unsigned char const *buf, uint32_t len)
{
        uint32_t t;

        /* Update bitcount */

        t = ctx->bits[0];
        if ((ctx->bits[0] = t + (len << 3)) < t)
                ctx->bits[1]++;         /* Carry from low to high */
        ctx->bits[1] += len >> 29;

        t = (t >> 3) & 0x3f;    /* Bytes already in shsInfo->data */

        /* Handle any leading odd-sized chunks */

        if (t) {
                unsigned char *p = (unsigned char *) ctx->in + t;

                t = 64 - t;
                if (len < t) {
                        memcpy(p, buf, len);
                        return;
                }
                memcpy(p, buf, t);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32_t *) ctx->in);
                buf += t;
                len -= t;
        }
        /* Process data in 64-byte chunks */

        while (len >= 64) {
                memcpy(ctx->in, buf, 64);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32_t *) ctx->in);
                buf += 64;
                len -= 64;
        }

        /* Handle any remaining bytes of data. */

        memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
static void
MD5Final(unsigned char digest[16], MD5_CTX *ctx)
{
        unsigned count;
        unsigned char *p;

        /* Compute number of bytes mod 64 */
        count = (ctx->bits[0] >> 3) & 0x3F;

        /* Set the first char of padding to 0x80.  This is safe since there is
           always at least one byte free */
        p = ctx->in + count;
        *p++ = 0x80;

        /* Bytes of padding needed to make 64 bytes */
        count = 64 - 1 - count;

        /* Pad out to 56 mod 64 */
        if (count < 8) {
                /* Two lots of padding:  Pad the first block to 64 bytes */
                memset(p, 0, count);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32_t *) ctx->in);

                /* Now fill the next block with 56 bytes */
                memset(ctx->in, 0, 56);
        } else {
                /* Pad block to 56 bytes */
                memset(p, 0, count - 8);
        }
        byteReverse(ctx->in, 14);

        /* Append length in bits and transform */
        ((uint32_t *) ctx->in)[14] = ctx->bits[0];
        ((uint32_t *) ctx->in)[15] = ctx->bits[1];

        MD5Transform(ctx->buf, (uint32_t *) ctx->in);
        byteReverse((unsigned char *) ctx->buf, 4);
        memcpy(digest, ctx->buf, 16);
        memset((char *) ctx, 0, sizeof(ctx));   /* In case it's sensitive */
}
#endif /* !HAVE_MD5 */

/*
 * Stringify binary data. Output buffer must be twice as big as input,
 * because each byte takes 2 bytes in string representation
 */
static void
bin2str(char *to, const unsigned char *p, size_t len)
{
        static const char *hex = "0123456789abcdef";

        for (; len--; p++) {
                *to++ = hex[p[0] >> 4];
                *to++ = hex[p[0] & 0x0f];
        }
        *to = '\0';
}

/*
 * Return stringified MD5 hash for list of vectors.
 * buf must point to 33-bytes long buffer
 */
static void
mg_md5(char *buf, ...)
{
        unsigned char   hash[16];
        const char      *p;
        va_list         ap;
        MD5_CTX         ctx;

        MD5Init(&ctx);

        va_start(ap, buf);
        while ((p = va_arg(ap, const char *)) != NULL)
                MD5Update(&ctx, (unsigned char *) p, strlen(p));
        va_end(ap);

        MD5Final(hash, &ctx);
        bin2str(buf, hash, sizeof(hash));
}

/*
 * Check the user's password, return 1 if OK
 */
static bool_t
check_password(const char *method, const char *ha1, const char *uri,
                const char *nonce, const char *nc, const char *cnonce,
                const char *qop, const char *response)
{
        char    ha2[32 + 1], expected_response[32 + 1];

        /* XXX  Due to a bug in MSIE, we do not compare the URI  */
        /* Also, we do not check for authentication timeout */
        if (/*strcmp(dig->uri, c->ouri) != 0 || */
            strlen(response) != 32 /*||
            now - strtoul(dig->nonce, NULL, 10) > 3600 */)
                return (FALSE);

        mg_md5(ha2, method, ":", uri, NULL);
        mg_md5(expected_response, ha1, ":", nonce, ":", nc,
            ":", cnonce, ":", qop, ":", ha2, NULL);

        return (!mg_strcasecmp(response, expected_response));
}

/*
 * Use the global passwords file, if specified by auth_gpass option,
 * or search for .htpasswd in the requested directory.
 */
static FILE *
open_auth_file(struct mg_connection *conn, const char *path)
{
        struct mg_context       *ctx = conn->ctx;
        char                    name[FILENAME_MAX];
        const char              *p, *e;
        struct mgstat           st;
        FILE                    *fp;

        if (ctx->options[OPT_AUTH_GPASSWD] != NULL) {
                /* Use global passwords file */
                fp =  mg_fopen(ctx->options[OPT_AUTH_GPASSWD], "r");
                if (fp == NULL)
                        cry(fc(ctx), "fopen(%s): %s",
                            ctx->options[OPT_AUTH_GPASSWD], strerror(ERRNO));
        } else if (!mg_stat(path, &st) && st.is_directory) {
                (void) mg_snprintf(conn, name, sizeof(name), "%s%c%s",
                    path, DIRSEP, PASSWORDS_FILE_NAME);
                fp = mg_fopen(name, "r");
        } else {
                /*
                 * Try to find .htpasswd in requested directory.
                 * Given the path, create the path to .htpasswd file
                 * in the same directory. Find the right-most
                 * directory separator character first. That would be the
                 * directory name. If directory separator character is not
                 * found, 'e' will point to 'p'.
                 */
                for (p = path, e = p + strlen(p) - 1; e > p; e--)
                        if (IS_DIRSEP_CHAR(*e))
                                break;

                /*
                 * Make up the path by concatenating directory name and
                 * .htpasswd file name.
                 */
                (void) mg_snprintf(conn, name, sizeof(name), "%.*s%c%s",
                    (int) (e - p), p, DIRSEP, PASSWORDS_FILE_NAME);
                fp = mg_fopen(name, "r");
        }

        return (fp);
}

/*
 * Parsed Authorization: header
 */
struct ah {
        char    *user, *uri, *cnonce, *response, *qop, *nc, *nonce;
};

static bool_t
parse_auth_header(struct mg_connection *conn, char *buf, size_t buf_size,
                struct ah *ah)
{
        char            *name, *value, *s;
        const char      *auth_header;

        if ((auth_header = mg_get_header(conn, "Authorization")) == NULL ||
            mg_strncasecmp(auth_header, "Digest ", 7) != 0)
                return (FALSE);

        /* Make modifiable copy of the auth header */
        (void) mg_strlcpy(buf, auth_header + 7, buf_size);

        s = buf;
        (void) memset(ah, 0, sizeof(*ah));

        /* Gobble initial spaces */
        while (isspace(* (unsigned char *) s))
                s++;

        /* Parse authorization header */
        for (;;) {
                name = skip(&s, "=");
                value = skip(&s, ", ");

                if (*value == '"') {
                        value++;
                        value[strlen(value) - 1] = '\0';
                } else if (*value == '\0') {
                        break;
                }

                if (!strcmp(name, "username")) {
                        ah->user = value;
                } else if (!strcmp(name, "cnonce")) {
                        ah->cnonce = value;
                } else if (!strcmp(name, "response")) {
                        ah->response = value;
                } else if (!strcmp(name, "uri")) {
                        ah->uri = value;
                } else if (!strcmp(name, "qop")) {
                        ah->qop = value;
                } else if (!strcmp(name, "nc")) {
                        ah->nc = value;
                } else if (!strcmp(name, "nonce")) {
                        ah->nonce = value;
                }
        }

        /* CGI needs it as REMOTE_USER */
        if (ah->user != NULL)
                conn->request_info.remote_user = mg_strdup(ah->user);

        return (TRUE);
}

/*
 * Authorize against the opened passwords file. Return 1 if authorized.
 */
static bool_t
authorize(struct mg_connection *conn, FILE *fp)
{
        struct ah       ah;
        char            line[256], f_user[256], domain[256], ha1[256],
                        buf[MAX_REQUEST_SIZE];

        if (!parse_auth_header(conn, buf, sizeof(buf), &ah))
                return (FALSE);

        /* Loop over passwords file */
        while (fgets(line, sizeof(line), fp) != NULL) {

                if (sscanf(line, "%[^:]:%[^:]:%s", f_user, domain, ha1) != 3)
                        continue;

                if (!strcmp(ah.user, f_user) &&
                    !strcmp(domain, conn->ctx->options[OPT_AUTH_DOMAIN]))
                        return (check_password(
                            conn->request_info.request_method, ha1,
                            ah.uri, ah.nonce, ah.nc, ah.cnonce,
                            ah.qop, ah.response));
        }

        return (FALSE);
}

/*
 * Return TRUE if request is authorised, FALSE otherwise.
 */
static bool_t
check_authorization(struct mg_connection *conn, const char *path)
{
        FILE            *fp;
        char            fname[FILENAME_MAX];
        struct vec      uri_vec, filename_vec;
        const char      *list;
        bool_t          authorized;

        fp = NULL;
        authorized = TRUE;

        lock_option(conn->ctx, OPT_PROTECT);
        list = conn->ctx->options[OPT_PROTECT];
        while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
                if (!memcmp(conn->request_info.uri, uri_vec.ptr, uri_vec.len)) {
                        (void) mg_snprintf(conn, fname, sizeof(fname), "%.*s",
                            filename_vec.len, filename_vec.ptr);
                        if ((fp = mg_fopen(fname, "r")) == NULL)
                                cry(conn, "%s: cannot open %s: %s",
                                    __func__, fname, strerror(errno));
                        break;
                }
        }
        unlock_option(conn->ctx, OPT_PROTECT);

        if (fp == NULL)
                fp = open_auth_file(conn, path);

        if (fp != NULL) {
                authorized = authorize(conn, fp);
                (void) fclose(fp);
        }

        return (authorized);
}

static void
send_authorization_request(struct mg_connection *conn)
{
        conn->request_info.status_code = 401;
        (void) mg_printf(conn,
            "HTTP/1.1 401 Unauthorized\r\n"
            "WWW-Authenticate: Digest qop=\"auth\", "
            "realm=\"%s\", nonce=\"%lu\"\r\n\r\n",
            conn->ctx->options[OPT_AUTH_DOMAIN], (unsigned long) time(NULL));
}

static bool_t
is_authorized_for_put(struct mg_connection *conn)
{
        FILE    *fp;
        int     ret = FALSE;

        if ((fp = mg_fopen(conn->ctx->options[OPT_AUTH_PUT], "r")) != NULL) {
                set_close_on_exec(fileno(fp));
                ret = authorize(conn, fp);
                (void) fclose(fp);
        }

        return (ret);
}

int
mg_modify_passwords_file(struct mg_context *ctx, const char *fname,
                const char *user, const char *pass)
{
        int             found;
        char            line[512], u[512], d[512], ha1[33], tmp[FILENAME_MAX];
        const char      *domain;
        FILE            *fp, *fp2;

        found = 0;
        fp = fp2 = NULL;
        domain = ctx->options[OPT_AUTH_DOMAIN];

        /* Regard empty password as no password - remove user record. */
        if (pass[0] == '\0')
                pass = NULL;

        (void) snprintf(tmp, sizeof(tmp), "%s.tmp", fname);

        /* Create the file if does not exist */
        if ((fp = mg_fopen(fname, "a+")) != NULL)
                (void) fclose(fp);

        /* Open the given file and temporary file */
        if ((fp = mg_fopen(fname, "r")) == NULL) {
                cry(fc(ctx), "Cannot open %s: %s", fname, strerror(errno));
                return (0);
        } else if ((fp2 = mg_fopen(tmp, "w+")) == NULL) {
                cry(fc(ctx), "Cannot open %s: %s", tmp, strerror(errno));
                return (0);
        }

        /* Copy the stuff to temporary file */
        while (fgets(line, sizeof(line), fp) != NULL) {

                if (sscanf(line, "%[^:]:%[^:]:%*s", u, d) != 2)
                        continue;

                if (!strcmp(u, user) && !strcmp(d, domain)) {
                        found++;
                        if (pass != NULL) {
                                mg_md5(ha1, user, ":", domain, ":", pass, NULL);
                                fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
                        }
                } else {
                        (void) fprintf(fp2, "%s", line);
                }
        }

        /* If new user, just add it */
        if (!found && pass != NULL) {
                mg_md5(ha1, user, ":", domain, ":", pass, NULL);
                (void) fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
        }

        /* Close files */
        (void) fclose(fp);
        (void) fclose(fp2);

        /* Put the temp file in place of real file */
        (void) mg_remove(fname);
        (void) mg_rename(tmp, fname);

        return (0);
}

struct de {
        struct mg_connection    *conn;
        char                    *file_name;
        struct mgstat           st;
};

static void
url_encode(const char *src, char *dst, size_t dst_len)
{
        const char      *dont_escape = "._-$,;~()";
        const char      *hex = "0123456789abcdef";
        const char      *end = dst + dst_len - 1;
        
        for (; *src != '\0' && dst < end; src++, dst++) {
                if (isalnum(*(unsigned char *) src) ||
                    strchr(dont_escape, * (unsigned char *) src) != NULL) {
                        *dst = *src;
                } else if (dst + 2 < end) {
                        dst[0] = '%';
                        dst[1] = hex[(* (unsigned char *) src) >> 4];
                        dst[2] = hex[(* (unsigned char *) src) & 0xf];
                        dst += 2;
                }
        }

        *dst = '\0';
}

/*
 * This function is called from send_directory() and prints out
 * single directory entry.
 */
static void
print_dir_entry(struct de *de)
{
        char            size[64], mod[64], href[FILENAME_MAX];

        if (de->st.is_directory) {
                (void) mg_snprintf(de->conn,
                    size, sizeof(size), "%s", "[DIRECTORY]");
        } else {
                /*
                 * We use (signed) cast below because MSVC 6 compiler cannot
                 * convert unsigned __int64 to double. Sigh.
                 */
                if (de->st.size < 1024)
                        (void) mg_snprintf(de->conn, size, sizeof(size),
                            "%lu", (unsigned long) de->st.size);
                else if (de->st.size < 0x100000 /* 1024 * 1024 */)
                        (void) mg_snprintf(de->conn, size, sizeof(size),
                            "%.1fk", (double) de->st.size / 1024.0);
                else if (de->st.size < 0x40000000 /* 1024 * 1024 * 1024 */)
                        (void) mg_snprintf(de->conn, size, sizeof(size),
                            "%.1fM", (double) de->st.size / 1048576);
                else
                        (void) mg_snprintf(de->conn, size, sizeof(size),
                          "%.1fG", (double) de->st.size / 1073741824);
        }
        (void) strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M",
                localtime(&de->st.mtime));

        url_encode(de->file_name, href, sizeof(href));

        de->conn->num_bytes_sent += mg_printf(de->conn,
            "<tr><td><a href=\"%s%s%s\">%s%s</a></td>"
            "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
            de->conn->request_info.uri, href, de->st.is_directory ? "/" : "",
            de->file_name, de->st.is_directory ? "/" : "", mod, size);
}

/*
 * This function is called from send_directory() and used for
 * sorting direcotory entries by size, or name, or modification time.
 */
static int
compare_dir_entries(const void *p1, const void *p2)
{
        const struct de *a = (struct de *) p1, *b = (struct de *) p2;
        const char      *query_string = a->conn->request_info.query_string;
        int             cmp_result = 0;

        if (query_string == NULL)
                query_string = "na";

        if (a->st.is_directory && !b->st.is_directory) {
                return (-1);  /* Always put directories on top */
        } else if (!a->st.is_directory && b->st.is_directory) {
                return (1);   /* Always put directories on top */
        } else if (*query_string == 'n') {
                cmp_result = strcmp(a->file_name, b->file_name);
        } else if (*query_string == 's') {
                cmp_result = a->st.size == b->st.size ? 0 :
                        a->st.size > b->st.size ? 1 : -1;
        } else if (*query_string == 'd') {
                cmp_result = a->st.mtime == b->st.mtime ? 0 :
                        a->st.mtime > b->st.mtime ? 1 : -1;
        }

        return (query_string[1] == 'd' ? -cmp_result : cmp_result);
}

/*
 * Send directory contents.
 */
static void
send_directory(struct mg_connection *conn, const char *dir)
{
        struct dirent   *dp;
        DIR             *dirp;
        struct de       *entries = NULL;
        char            path[FILENAME_MAX];
        int             i, sort_direction, num_entries = 0, arr_size = 128;

        if ((dirp = opendir(dir)) == NULL) {
                send_error(conn, 500, "Cannot open directory",
                    "Error: opendir(%s): %s", path, strerror(ERRNO));
                return;
        }

        (void) mg_printf(conn, "%s",
            "HTTP/1.1 200 OK\r\n"
            "Connection: close\r\n"
            "Content-Type: text/html; charset=utf-8\r\n\r\n");

        sort_direction = conn->request_info.query_string != NULL &&
            conn->request_info.query_string[1] == 'd' ? 'a' : 'd';

        while ((dp = readdir(dirp)) != NULL) {

                /* Do not show current dir and passwords file */
                if (!strcmp(dp->d_name, ".") ||
                    !strcmp(dp->d_name, "..") ||
                    !strcmp(dp->d_name, PASSWORDS_FILE_NAME))
                        continue;

                if (entries == NULL || num_entries >= arr_size) {
                        arr_size *= 2;
                        entries = (struct de *) realloc(entries,
                            arr_size * sizeof(entries[0]));
                }

                if (entries == NULL) {
                        send_error(conn, 500, "Cannot open directory",
                            "%s", "Error: cannot allocate memory");
                        return;
                }

                (void) mg_snprintf(conn, path, sizeof(path), "%s%c%s",
                    dir, DIRSEP, dp->d_name);

                /*
                 * If we don't memset stat structure to zero, mtime will have
                 * garbage and strftime() will segfault later on in
                 * print_dir_entry(). memset is required only if mg_stat()
                 * fails. For more details, see
                 * http://code.google.com/p/mongoose/issues/detail?id=79
                 */
                if (mg_stat(path, &entries[num_entries].st) != 0)
                        (void) memset(&entries[num_entries].st, 0,
                            sizeof(entries[num_entries].st));

                entries[num_entries].conn = conn;
                entries[num_entries].file_name = mg_strdup(dp->d_name);
                num_entries++;
        }
        (void) closedir(dirp);

        conn->num_bytes_sent += mg_printf(conn,
            "<html><head><title>Index of %s</title>"
            "<style>th {text-align: left;}</style></head>"
            "<body><h1>Index of %s</h1><pre><table cellpadding=\"0\">"
            "<tr><th><a href=\"?n%c\">Name</a></th>"
            "<th><a href=\"?d%c\">Modified</a></th>"
            "<th><a href=\"?s%c\">Size</a></th></tr>"
            "<tr><td colspan=\"3\"><hr></td></tr>",
            conn->request_info.uri, conn->request_info.uri,
            sort_direction, sort_direction, sort_direction);

        /* Print first entry - link to a parent directory */
        conn->num_bytes_sent += mg_printf(conn,
            "<tr><td><a href=\"%s%s\">%s</a></td>"
            "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
            conn->request_info.uri, "..", "Parent directory", "-", "-");

        /* Sort and print directory entries */
        qsort(entries, num_entries, sizeof(entries[0]), compare_dir_entries);
        for (i = 0; i < num_entries; i++) {
                print_dir_entry(&entries[i]);
                free(entries[i].file_name);
        }
        free(entries);

        conn->num_bytes_sent += mg_printf(conn, "%s", "</table></body></html>");
        conn->request_info.status_code = 200;
}

/*
 * Send len bytes from the opened file to the client.
 */
static void
send_opened_file_stream(struct mg_connection *conn, FILE *fp, int64_t len)
{
        char    buf[BUFSIZ];
        int     to_read, num_read, num_written;

        while (len > 0) {
                /* Calculate how much to read from the file in the buffer */
                to_read = sizeof(buf);
                if ((int64_t) to_read > len)
                        to_read = (int) len;

                /* Read from file, exit the loop on error */
                if ((num_read = fread(buf, 1, to_read, fp)) == 0)
                        break;

                /* Send read bytes to the client, exit the loop on error */
                if ((num_written = mg_write(conn, buf, num_read)) != num_read)
                        break;

                /* Both read and were successful, adjust counters */
                conn->num_bytes_sent += num_written;
                len -= num_written;
        }
}

/*
 * Send regular file contents.
 */
static void
send_file(struct mg_connection *conn, const char *path, struct mgstat *stp)
{
        char            date[64], lm[64], etag[64], range[64];
        const char      *fmt = "%a, %d %b %Y %H:%M:%S %Z", *msg = "OK", *hdr;
        time_t          curtime = time(NULL);
        int64_t         cl, r1, r2;
        struct vec      mime_vec;
        FILE            *fp;
        int             n;

        get_mime_type(conn->ctx, path, &mime_vec);
        cl = stp->size;
        conn->request_info.status_code = 200;
        range[0] = '\0';

        if ((fp = mg_fopen(path, "rb")) == NULL) {
                send_error(conn, 500, http_500_error,
                    "fopen(%s): %s", path, strerror(ERRNO));
                return;
        }
        set_close_on_exec(fileno(fp));

        /* If Range: header specified, act accordingly */
        r1 = r2 = 0;
        hdr = mg_get_header(conn, "Range");
        if (hdr != NULL && (n = sscanf(hdr,
            "bytes=%" INT64_FMT "-%" INT64_FMT, &r1, &r2)) > 0) {
                conn->request_info.status_code = 206;
                (void) fseeko(fp, (off_t) r1, SEEK_SET);
                cl = n == 2 ? r2 - r1 + 1: cl - r1;
                (void) mg_snprintf(conn, range, sizeof(range),
                    "Content-Range: bytes "
                    "%" INT64_FMT "-%"
                    INT64_FMT "/%" INT64_FMT "\r\n",
                    r1, r1 + cl - 1, stp->size);
                msg = "Partial Content";
        }

        /* Prepare Etag, Date, Last-Modified headers */
        (void) strftime(date, sizeof(date), fmt, localtime(&curtime));
        (void) strftime(lm, sizeof(lm), fmt, localtime(&stp->mtime));
        (void) mg_snprintf(conn, etag, sizeof(etag), "%lx.%lx",
            (unsigned long) stp->mtime, (unsigned long) stp->size);

        (void) mg_printf(conn,
            "HTTP/1.1 %d %s\r\n"
            "Date: %s\r\n"
            "Last-Modified: %s\r\n"
            "Etag: \"%s\"\r\n"
            "Content-Type: %.*s\r\n"
            "Content-Length: %" INT64_FMT "\r\n"
            "Connection: close\r\n"
            "Accept-Ranges: bytes\r\n"
            "%s\r\n",
            conn->request_info.status_code, msg, date, lm, etag,
            mime_vec.len, mime_vec.ptr, cl, range);

        if (strcmp(conn->request_info.request_method, "HEAD") != 0)
                send_opened_file_stream(conn, fp, cl);
        (void) fclose(fp);
}

/*
 * Parse HTTP headers from the given buffer, advance buffer to the point
 * where parsing stopped.
 */
static void
parse_http_headers(char **buf, struct mg_request_info *ri)
{
        int     i;

        for (i = 0; i < (int) ARRAY_SIZE(ri->http_headers); i++) {
                ri->http_headers[i].name = skip(buf, ": ");
                ri->http_headers[i].value = skip(buf, "\r\n");
                if (ri->http_headers[i].name[0] == '\0')
                        break;
                ri->num_headers = i + 1;
        }
}

static bool_t
is_valid_http_method(const char *method)
{
        return (!strcmp(method, "GET") ||
            !strcmp(method, "POST") ||
            !strcmp(method, "HEAD") ||
            !strcmp(method, "PUT") ||
            !strcmp(method, "DELETE"));
}

/*
 * Parse HTTP request, fill in mg_request_info structure.
 */
static bool_t
parse_http_request(char *buf, struct mg_request_info *ri, const struct usa *usa)
{
        int     success_code = FALSE;

        ri->request_method = skip(&buf, " ");
        ri->uri = skip(&buf, " ");
        ri->http_version = skip(&buf, "\r\n");

        if (is_valid_http_method(ri->request_method) &&
            ri->uri[0] == '/' &&
            strncmp(ri->http_version, "HTTP/", 5) == 0) {
                ri->http_version += 5;   /* Skip "HTTP/" */
                parse_http_headers(&buf, ri);
                ri->remote_port = ntohs(usa->u.sin.sin_port);
                (void) memcpy(&ri->remote_ip, &usa->u.sin.sin_addr.s_addr, 4);
                ri->remote_ip = ntohl(ri->remote_ip);
                success_code = TRUE;
        }

        return (success_code);
}

/*
 * Keep reading the input (either opened file descriptor fd, or socket sock,
 * or SSL descriptor ssl) into buffer buf, until \r\n\r\n appears in the
 * buffer (which marks the end of HTTP request). Buffer buf may already
 * have some data. The length of the data is stored in nread.
 * Upon every read operation, increase nread by the number of bytes read.
 */
static int
read_request(FILE *fp, SOCKET sock, SSL *ssl, char *buf, int bufsiz, int *nread)
{
        int     n, request_len;

        request_len = 0;
        while (*nread < bufsiz && request_len == 0) {
                n = pull(fp, sock, ssl, buf + *nread, bufsiz - *nread);
                if (n <= 0) {
                        break;
                } else {
                        *nread += n;
                        request_len = get_request_len(buf, (size_t) *nread);
                }
        }

        return (request_len);
}

/*
 * For given directory path, substitute it to valid index file.
 * Return 0 if index file has been found, -1 if not found.
 * If the file is found, it's stats is returned in stp.
 */
static bool_t
substitute_index_file(struct mg_connection *conn,
                char *path, size_t path_len, struct mgstat *stp)
{
        const char      *list;
        struct mgstat   st;
        struct vec      filename_vec;
        size_t          n;
        bool_t          found;

        n = strlen(path);

        /*
         * The 'path' given to us points to the directory. Remove all trailing
         * directory separator characters from the end of the path, and
         * then append single directory separator character.
         */
        while (n > 0 && IS_DIRSEP_CHAR(path[n - 1]))
                n--;
        path[n] = DIRSEP;

        /*
         * Traverse index files list. For each entry, append it to the given
         * path and see if the file exists. If it exists, break the loop
         */
        lock_option(conn->ctx, OPT_INDEX_FILES);
        list = conn->ctx->options[OPT_INDEX_FILES];
        found = FALSE;

        while ((list = next_option(list, &filename_vec, NULL)) != NULL) {

                /* Ignore too long entries that may overflow path buffer */
                if (filename_vec.len > path_len - n)
                        continue;

                /* Prepare full path to the index file  */
                (void) mg_strlcpy(path + n + 1,
                    filename_vec.ptr, filename_vec.len + 1);

                /* Does it exist ? */
                if (mg_stat(path, &st) == 0) {
                        /* Yes it does, break the loop */
                        *stp = st;
                        found = TRUE;
                        break;
                }
        }
        unlock_option(conn->ctx, OPT_INDEX_FILES);

        /* If no index file exists, restore directory path */
        if (found == FALSE)
                path[n] = '\0';

        return (found);
}

static void
remove_callback(struct mg_context *ctx,
                const char *uri_regex, int status_code, bool_t is_auth)
{
        struct callback *cb;
        int             i;

        for (i = 0; i < ctx->num_callbacks; i++) {
                cb = ctx->callbacks + i;
                if ((uri_regex != NULL && cb->uri_regex != NULL &&
                    ((is_auth && cb->is_auth) || (!is_auth && !cb->is_auth)) &&
                    !strcmp(uri_regex, cb->uri_regex)) || (uri_regex == NULL &&
                     (cb->status_code == 0 ||
                      cb->status_code == status_code))) {
                        (void) memmove(cb, cb + 1,
                            (char *) (ctx->callbacks + ctx->num_callbacks) -
                            (char *) (cb + 1));
                        break;
                }
        }
}

static void
add_callback(struct mg_context *ctx, const char *uri_regex, int status_code,
                mg_callback_t func, bool_t is_auth, void *user_data)
{
        struct callback *cb;

        pthread_mutex_lock(&ctx->bind_mutex);
        if (func == NULL) {
                remove_callback(ctx, uri_regex, status_code, is_auth);
        } else if (ctx->num_callbacks >= (int) ARRAY_SIZE(ctx->callbacks) - 1) {
                cry(fc(ctx), "Too many callbacks! Increase MAX_CALLBACKS.");
        } else {
                cb = &ctx->callbacks[ctx->num_callbacks];
                cb->uri_regex = uri_regex ? mg_strdup(uri_regex) : NULL;
                cb->func = func;
                cb->is_auth = is_auth;
                cb->status_code = status_code;
                cb->user_data = user_data;
                ctx->num_callbacks++;
                DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: uri %s code %d",
                    __func__, uri_regex ? uri_regex : "NULL", status_code));
        }
        pthread_mutex_unlock(&ctx->bind_mutex);
}

void
mg_set_uri_callback(struct mg_context *ctx, const char *uri_regex,
                mg_callback_t func, void *user_data)
{
        assert(uri_regex != NULL);
        add_callback(ctx, uri_regex, -1, func, FALSE, user_data);
}

void
mg_set_error_callback(struct mg_context *ctx, int error_code,
                mg_callback_t func, void *user_data)
{
        assert(error_code >= 0 && error_code < 1000);
        add_callback(ctx, NULL, error_code, func, FALSE, user_data);
}

void
mg_set_auth_callback(struct mg_context *ctx, const char *uri_regex,
                mg_callback_t func, void *user_data)
{
        assert(uri_regex != NULL);
        add_callback(ctx, uri_regex, -1, func, TRUE, user_data);
}

/*
 * Return True if we should reply 304 Not Modified.
 */
static bool_t
is_not_modified(const struct mg_connection *conn, const struct mgstat *stp)
{
        const char *ims = mg_get_header(conn, "If-Modified-Since");
        return (ims != NULL && stp->mtime < date_to_epoch(ims));
}

static bool_t
append_chunk(struct mg_request_info *ri, FILE *fp, const char *buf, int len)
{
        bool_t  ret_code = TRUE;

        if (fp == NULL) {
                /* TODO: check for NULL here */
                ri->post_data = (char *) realloc(ri->post_data,
                    ri->post_data_len + len);
                (void) memcpy(ri->post_data + ri->post_data_len, buf, len);
                ri->post_data_len += len;
        } else if (push(fp, INVALID_SOCKET,
            NULL, buf, (int64_t) len) != (int64_t) len) {
                ret_code = FALSE;
        }

        return (ret_code);
}

static bool_t
handle_request_body(struct mg_connection *conn, FILE *fp)
{
        struct mg_request_info  *ri = &conn->request_info;
        const char      *expect, *tmp;
        int64_t         content_len;
        char            buf[BUFSIZ];
        int             to_read, nread, already_read;
        bool_t          success_code = FALSE;

        content_len = get_content_length(conn);
        expect = mg_get_header(conn, "Expect");

        if (content_len == -1) {
                send_error(conn, 411, "Length Required", "");
        } else if (expect != NULL && mg_strcasecmp(expect, "100-continue")) {
                send_error(conn, 417, "Expectation Failed", "");
        } else {
                if (expect != NULL)
                        (void) mg_printf(conn, "HTTP/1.1 100 Continue\r\n\r\n");

                already_read = ri->post_data_len;
                assert(already_read >= 0);

                if (content_len <= (int64_t) already_read) {
                        ri->post_data_len = (int) content_len;
                        /*
                         * If fp is NULL, this is embedded mode, and we do not
                         * have to do anything: POST data is already there,
                         * no need to allocate a buffer and copy it in.
                         * If fp != NULL, we need to write the data.
                         */
                        success_code = fp == NULL || (push(fp, INVALID_SOCKET,
                            NULL, ri->post_data, content_len) == content_len) ?
                            TRUE : FALSE;
                } else {

                        if (fp == NULL) {
                                conn->free_post_data = TRUE;
                                tmp = ri->post_data;
                                /* +1 in case if already_read == 0 */
                                ri->post_data = (char*)malloc(already_read + 1);
                                (void) memcpy(ri->post_data, tmp, already_read);
                        } else {
                                (void) push(fp, INVALID_SOCKET, NULL,
                                    ri->post_data, (int64_t) already_read);
                        }

                        content_len -= already_read;

                        while (content_len > 0) {
                                to_read = sizeof(buf);
                                if ((int64_t) to_read > content_len)
                                        to_read = (int) content_len;
                                nread = pull(NULL, conn->client.sock,
                                    conn->ssl, buf, to_read);
                                if (nread <= 0)
                                        break;
                                if (!append_chunk(ri, fp, buf, nread))
                                        break;
                                content_len -= nread;
                        }
                        success_code = content_len == 0 ? TRUE : FALSE;
                }

                /* Each error code path in this function must send an error */
                if (success_code != TRUE)
                        send_error(conn, 577, http_500_error,
                            "%s", "Error handling body data");
        }

        return (success_code);
}

#if !defined(NO_CGI)

/*
 * This structure helps to create an environment for the spawned CGI program.
 * Environment is an array of "VARIABLE=VALUE\0" ASCIIZ strings,
 * last element must be NULL.
 * However, on Windows there is a requirement that all these VARIABLE=VALUE\0
 * strings must reside in a contiguous buffer. The end of the buffer is
 * marked by two '\0' characters.
 * We satisfy both worlds: we create an envp array (which is vars), all
 * entries are actually pointers inside buf.
 */
struct cgi_env_block {
        struct mg_connection *conn;
        char    buf[CGI_ENVIRONMENT_SIZE];      /* Environment buffer   */
        int     len;                            /* Space taken          */
        char    *vars[MAX_CGI_ENVIR_VARS];      /* char **envp          */
        int     nvars;                          /* Number of variables  */
};

/*
 * Append VARIABLE=VALUE\0 string to the buffer, and add a respective
 * pointer into the vars array.
 */
static char *
addenv(struct cgi_env_block *block, const char *fmt, ...)
{
        int     n, space;
        char    *added;
        va_list ap;

        /* Calculate how much space is left in the buffer */
        space = sizeof(block->buf) - block->len - 2;
        assert(space >= 0);

        /* Make a pointer to the free space int the buffer */
        added = block->buf + block->len;

        /* Copy VARIABLE=VALUE\0 string into the free space */
        va_start(ap, fmt);
        n = mg_vsnprintf(block->conn, added, (size_t) space, fmt, ap);
        va_end(ap);

        /* Make sure we do not overflow buffer and the envp array */
        if (n > 0 && n < space &&
            block->nvars < (int) ARRAY_SIZE(block->vars) - 2) {
                /* Append a pointer to the added string into the envp array */
                block->vars[block->nvars++] = block->buf + block->len;
                /* Bump up used length counter. Include \0 terminator */
                block->len += n + 1;
        }

        return (added);
}

static void
prepare_cgi_environment(struct mg_connection *conn, const char *prog,
                struct cgi_env_block *blk)
{
        const char      *s, *script_filename, *root, *slash;
        struct vec      var_vec;
        char            *p;
        int             i;

        blk->len = blk->nvars = 0;
        blk->conn = conn;

        /* SCRIPT_FILENAME */
        script_filename = prog;
        if ((s = strrchr(prog, '/')) != NULL)
                script_filename = s + 1;

        lock_option(conn->ctx, OPT_ROOT);
        root = conn->ctx->options[OPT_ROOT];
        addenv(blk, "SERVER_NAME=%s", conn->ctx->options[OPT_AUTH_DOMAIN]);
        unlock_option(conn->ctx, OPT_ROOT);

        /* Prepare the environment block */
        addenv(blk, "%s", "GATEWAY_INTERFACE=CGI/1.1");
        addenv(blk, "%s", "SERVER_PROTOCOL=HTTP/1.1");
        addenv(blk, "%s", "REDIRECT_STATUS=200");       /* PHP */
        addenv(blk, "SERVER_PORT=%d", ntohs(conn->client.lsa.u.sin.sin_port));
        addenv(blk, "SERVER_ROOT=%s", root);
        addenv(blk, "DOCUMENT_ROOT=%s", root);
        addenv(blk, "REQUEST_METHOD=%s", conn->request_info.request_method);
        addenv(blk, "REMOTE_ADDR=%s",
            inet_ntoa(conn->client.rsa.u.sin.sin_addr));
        addenv(blk, "REMOTE_PORT=%d", conn->request_info.remote_port);
        addenv(blk, "REQUEST_URI=%s", conn->request_info.uri);

        slash = strrchr(conn->request_info.uri, '/');
        addenv(blk, "SCRIPT_NAME=%.*s%s",
            (slash - conn->request_info.uri) + 1, conn->request_info.uri,
            script_filename);

        addenv(blk, "SCRIPT_FILENAME=%s", script_filename);     /* PHP */
        addenv(blk, "PATH_TRANSLATED=%s", prog);
        addenv(blk, "HTTPS=%s", conn->ssl == NULL ? "off" : "on");

        if ((s = mg_get_header(conn, "Content-Type")) != NULL)
                addenv(blk, "CONTENT_TYPE=%s", s);

        if (conn->request_info.query_string != NULL)
                addenv(blk, "QUERY_STRING=%s", conn->request_info.query_string);

        if ((s = mg_get_header(conn, "Content-Length")) != NULL)
                addenv(blk, "CONTENT_LENGTH=%s", s);

        if ((s = getenv("PATH")) != NULL)
                addenv(blk, "PATH=%s", s);

#if defined(_WIN32)
        if ((s = getenv("COMSPEC")) != NULL)
                addenv(blk, "COMSPEC=%s", s);
        if ((s = getenv("SYSTEMROOT")) != NULL)
                addenv(blk, "SYSTEMROOT=%s", s);
#else
        if ((s = getenv("LD_LIBRARY_PATH")) != NULL)
                addenv(blk, "LD_LIBRARY_PATH=%s", s);
#endif /* _WIN32 */

        if ((s = getenv("PERLLIB")) != NULL)
                addenv(blk, "PERLLIB=%s", s);

        if (conn->request_info.remote_user != NULL) {
                addenv(blk, "REMOTE_USER=%s", conn->request_info.remote_user);
                addenv(blk, "%s", "AUTH_TYPE=Digest");
        }

        /* Add all headers as HTTP_* variables */
        for (i = 0; i < conn->request_info.num_headers; i++) {
                p = addenv(blk, "HTTP_%s=%s",
                    conn->request_info.http_headers[i].name,
                    conn->request_info.http_headers[i].value);

                /* Convert variable name into uppercase, and change - to _ */
                for (; *p != '=' && *p != '\0'; p++) {
                        if (*p == '-')
                                *p = '_';
                        *p = (char) toupper(* (unsigned char *) p);
                }
        }

        /* Add user-specified variables */
        lock_option(conn->ctx, OPT_CGI_ENV);
        s = conn->ctx->options[OPT_CGI_ENV];
        while ((s = next_option(s, &var_vec, NULL)) != NULL)
                addenv(blk, "%.*s", var_vec.len, var_vec.ptr);
        unlock_option(conn->ctx, OPT_CGI_ENV);

        blk->vars[blk->nvars++] = NULL;
        blk->buf[blk->len++] = '\0';

        assert(blk->nvars < (int) ARRAY_SIZE(blk->vars));
        assert(blk->len > 0);
        assert(blk->len < (int) sizeof(blk->buf));
}

static void
send_cgi(struct mg_connection *conn, const char *prog)
{
        int                     headers_len, data_len, i;
        const char              *status;
        char                    buf[MAX_REQUEST_SIZE], *pbuf;
        struct mg_request_info  ri;
        struct cgi_env_block    blk;
        char                    dir[FILENAME_MAX], *p;
        int                     fd_stdin[2], fd_stdout[2];
        FILE                    *in, *out;
        pid_t                   pid;

        prepare_cgi_environment(conn, prog, &blk);

        /* CGI must be executed in its own directory */
        (void) mg_snprintf(conn, dir, sizeof(dir), "%s", prog);
        if ((p = strrchr(dir, DIRSEP)) != NULL)
                *p++ = '\0';

        pid = (pid_t) -1;
        fd_stdin[0] = fd_stdin[1] = fd_stdout[0] = fd_stdout[1] = -1;
        in = out = NULL;

        if (pipe(fd_stdin) != 0 || pipe(fd_stdout) != 0) {
                send_error(conn, 500, http_500_error,
                    "Cannot create CGI pipe: %s", strerror(ERRNO));
                goto done;
        } else if ((pid = spawn_process(conn, p, blk.buf, blk.vars,
            fd_stdin[0], fd_stdout[1], dir)) == (pid_t) -1) {
                goto done;
        } else if ((in = fdopen(fd_stdin[1], "wb")) == NULL ||
            (out = fdopen(fd_stdout[0], "rb")) == NULL) {
                send_error(conn, 500, http_500_error,
                    "fopen: %s", strerror(ERRNO));
                goto done;
        }

        setbuf(in, NULL);
        setbuf(out, NULL);

        /*
         * spawn_process() must close those!
         * If we don't mark them as closed, close() attempt before
         * return from this function throws an exception on Windows.
         * Windows does not like when closed descriptor is closed again.
         */
        fd_stdin[0] = fd_stdout[1] = -1;

        /* Send POST data to the CGI process if needed */
        if (!strcmp(conn->request_info.request_method, "POST") &&
            !handle_request_body(conn, in)) {
                goto done;
        }

        /*
         * Now read CGI reply into a buffer. We need to set correct
         * status code, thus we need to see all HTTP headers first.
         * Do not send anything back to client, until we buffer in all
         * HTTP headers.
         */
        data_len = 0;
        headers_len = read_request(out, INVALID_SOCKET, NULL,
            buf, sizeof(buf), &data_len);
        if (headers_len <= 0) {
                send_error(conn, 500, http_500_error,
                    "CGI program sent malformed HTTP headers: [%.*s]",
                    data_len, buf);
                goto done;
        }
        pbuf = buf;
        buf[headers_len - 1] = '\0';
        parse_http_headers(&pbuf, &ri);

        /* Make up and send the status line */
        status = get_header(&ri, "Status");
        conn->request_info.status_code = status == NULL ? 200 : atoi(status);
        (void) mg_printf(conn, "HTTP/1.1 %d OK\r\n",
            conn->request_info.status_code);

        /* Send headers */
        for (i = 0; i < ri.num_headers; i++)
                (void) mg_printf(conn, "%s: %s\r\n",
                    ri.http_headers[i].name,
                    ri.http_headers[i].value);
        (void) mg_write(conn, "\r\n", 2);

        /* Send chunk of data that may be read after the headers */
        conn->num_bytes_sent += mg_write(conn,
            buf + headers_len, data_len - headers_len);

        /* Read the rest of CGI output and send to the client */
        send_opened_file_stream(conn, out, INT64_MAX);

done:
        if (pid != (pid_t) -1)
                kill(pid, SIGTERM);
        if (fd_stdin[0] != -1)
                (void) close(fd_stdin[0]);
        if (fd_stdout[1] != -1)
                (void) close(fd_stdout[1]);

        if (in != NULL)
                (void) fclose(in);
        else if (fd_stdin[1] != -1)
                (void) close(fd_stdin[1]);

        if (out != NULL)
                (void) fclose(out);
        else if (fd_stdout[0] != -1)
                (void) close(fd_stdout[0]);
}
#endif /* !NO_CGI */

/*
 * For a given PUT path, create all intermediate subdirectories
 * for given path. Return 0 if the path itself is a directory,
 * or -1 on error, 1 if OK.
 */
static int
put_dir(const char *path)
{
        char            buf[FILENAME_MAX];
        const char      *s, *p;
        struct mgstat   st;
        size_t          len;

        for (s = p = path + 2; (p = strchr(s, '/')) != NULL; s = ++p) {
                len = p - path;
                assert(len < sizeof(buf));
                (void) memcpy(buf, path, len);
                buf[len] = '\0';

                /* Try to create intermediate directory */
                if (mg_stat(buf, &st) == -1 && mg_mkdir(buf, 0755) != 0)
                        return (-1);

                /* Is path itself a directory ? */
                if (p[1] == '\0')
                        return (0);
        }

        return (1);
}

static void
put_file(struct mg_connection *conn, const char *path)
{
        struct mgstat   st;
        FILE            *fp;
        int             rc;

        conn->request_info.status_code = mg_stat(path, &st) == 0 ? 200 : 201;

        if (mg_get_header(conn, "Range")) {
                send_error(conn, 501, "Not Implemented",
                    "%s", "Range support for PUT requests is not implemented");
        } else if ((rc = put_dir(path)) == 0) {
                (void) mg_printf(conn, "HTTP/1.1 %d OK\r\n\r\n",
                    conn->request_info.status_code);
        } else if (rc == -1) {
                send_error(conn, 500, http_500_error,
                    "put_dir(%s): %s", path, strerror(ERRNO));
        } else if ((fp = mg_fopen(path, "wb+")) == NULL) {
                send_error(conn, 500, http_500_error,
                    "fopen(%s): %s", path, strerror(ERRNO));
        } else {
                set_close_on_exec(fileno(fp));
                if (handle_request_body(conn, fp))
                        (void) mg_printf(conn, "HTTP/1.1 %d OK\r\n\r\n",
                            conn->request_info.status_code);
                (void) fclose(fp);
        }
}

#if !defined(NO_SSI)
static void send_ssi_file(struct mg_connection *, const char *, FILE *, int);

static void
do_ssi_include(struct mg_connection *conn, const char *ssi, char *tag,
                int include_level)
{
        char    file_name[BUFSIZ], path[FILENAME_MAX], *p;
        FILE    *fp;

        /*
         * sscanf() is safe here, since send_ssi_file() also uses buffer
         * of size BUFSIZ to get the tag. So strlen(tag) is always < BUFSIZ.
         */
        if (sscanf(tag, " virtual=\"%[^\"]\"", file_name) == 1) {
                /* File name is relative to the webserver root */
                lock_option(conn->ctx, OPT_ROOT);
                (void) mg_snprintf(conn, path, sizeof(path), "%s%c%s",
                    conn->ctx->options[OPT_ROOT], DIRSEP, file_name);
                unlock_option(conn->ctx, OPT_ROOT);
        } else if (sscanf(tag, " file=\"%[^\"]\"", file_name) == 1) {
                /*
                 * File name is relative to the webserver working directory
                 * or it is absolute system path
                 */
                (void) mg_snprintf(conn, path, sizeof(path), "%s", file_name);
        } else if (sscanf(tag, " \"%[^\"]\"", file_name) == 1) {
                /* File name is relative to the currect document */
                (void) mg_snprintf(conn, path, sizeof(path), "%s", ssi);
                if ((p = strrchr(path, DIRSEP)) != NULL)
                        p[1] = '\0';
                (void) mg_snprintf(conn, path + strlen(path),
                    sizeof(path) - strlen(path), "%s", file_name);
        } else {
                cry(conn, "Bad SSI #include: [%s]", tag);
                return;
        }

        if ((fp = mg_fopen(path, "rb")) == NULL) {
                cry(conn, "Cannot open SSI #include: [%s]: fopen(%s): %s",
                    tag, path, strerror(ERRNO));
        } else {
                set_close_on_exec(fileno(fp));
                if (match_extension(path,
                    conn->ctx->options[OPT_SSI_EXTENSIONS])) {
                        send_ssi_file(conn, path, fp, include_level + 1);
                } else {
                        send_opened_file_stream(conn, fp, INT64_MAX);
                }
                (void) fclose(fp);
        }
}

static void
do_ssi_exec(struct mg_connection *conn, char *tag)
{
        char    cmd[BUFSIZ];
        FILE    *fp;

        if (sscanf(tag, " \"%[^\"]\"", cmd) != 1) {
                cry(conn, "Bad SSI #exec: [%s]", tag);
        } else if ((fp = popen(cmd, "r")) == NULL) {
                cry(conn, "Cannot SSI #exec: [%s]: %s", cmd, strerror(ERRNO));
        } else {
                send_opened_file_stream(conn, fp, INT64_MAX);
                (void) pclose(fp);
        }
}

static void
send_ssi_file(struct mg_connection *conn, const char *path, FILE *fp,
                int include_level)
{
        char    buf[BUFSIZ];
        int     ch, len, in_ssi_tag;

        if (include_level > 10) {
                cry(conn, "SSI #include level is too deep (%s)", path);
                return;
        }

        in_ssi_tag = FALSE;
        len = 0;

        while ((ch = fgetc(fp)) != EOF) {
                if (in_ssi_tag && ch == '>') {
                        in_ssi_tag = FALSE;
                        buf[len++] = ch & 0xff;
                        buf[len] = '\0';
                        assert(len <= (int) sizeof(buf));
                        if (len < 6 || memcmp(buf, "<!--#", 5) != 0) {
                                /* Not an SSI tag, pass it */
                                (void) mg_write(conn, buf, len);
                        } else {
                                if (!memcmp(buf + 5, "include", 7)) {
                                        do_ssi_include(conn, path, buf + 12,
                                            include_level);
                                } else if (!memcmp(buf + 5, "exec", 4)) {
                                        do_ssi_exec(conn, buf + 9);
                                } else {
                                        cry(conn, "%s: unknown SSI "
                                            "command: \"%s\"", path, buf);
                                }
                        }
                        len = 0;
                } else if (in_ssi_tag) {
                        if (len == 5 && memcmp(buf, "<!--#", 5) != 0) {
                                /* Not an SSI tag */
                                in_ssi_tag = FALSE;
                        } else if (len == (int) sizeof(buf) - 2) {
                                cry(conn, "%s: SSI tag is too large", path);
                                len = 0;
                        }
                        buf[len++] = ch & 0xff;
                } else if (ch == '<') {
                        in_ssi_tag = TRUE;
                        if (len > 0)
                                (void) mg_write(conn, buf, len);
                        len = 0;
                        buf[len++] = ch & 0xff;
                } else {
                        buf[len++] = ch & 0xff;
                        if (len == (int) sizeof(buf)) {
                                (void) mg_write(conn, buf, len);
                                len = 0;
                        }
                }
        }

        /* Send the rest of buffered data */
        if (len > 0)
                (void) mg_write(conn, buf, len);

}

static void
send_ssi(struct mg_connection *conn, const char *path)
{
        FILE    *fp;

        if ((fp = mg_fopen(path, "rb")) == NULL) {
                send_error(conn, 500, http_500_error,
                    "fopen(%s): %s", path, strerror(ERRNO));
        } else {
                set_close_on_exec(fileno(fp));
                (void) mg_printf(conn, "%s", "HTTP/1.1 200 OK\r\n"
                    "Content-Type: text/html\r\nConnection: close\r\n\r\n");
                send_ssi_file(conn, path, fp, 0);
                (void) fclose(fp);
        }
}
#endif /* !NO_SSI */

void
mg_authorize(struct mg_connection *conn)
{
        conn->embedded_auth = TRUE;
}

static bool_t
check_embedded_authorization(struct mg_connection *conn)
{
        const struct callback   *cb;
        bool_t                  authorized;

        authorized = TRUE;
        cb = find_callback(conn->ctx, TRUE, conn->request_info.uri, -1);

        if (cb != NULL) {
                cb->func(conn, &conn->request_info, cb->user_data);
                authorized = conn->embedded_auth;
        }

        return (authorized);
}

/*
 * This is the heart of the Mongoose's logic.
 * This function is called when the request is read, parsed and validated,
 * and Mongoose must decide what action to take: serve a file, or
 * a directory, or call embedded function, etcetera.
 */
static void
analyze_request(struct mg_connection *conn)
{
        struct mg_request_info *ri = &conn->request_info;
        char                    path[FILENAME_MAX], *uri = ri->uri;
        struct mgstat           st;
        const struct callback   *cb;

        if ((conn->request_info.query_string = strchr(uri, '?')) != NULL)
                * conn->request_info.query_string++ = '\0';

        (void) url_decode(uri, (int) strlen(uri), uri, strlen(uri) + 1, FALSE);
        remove_double_dots_and_double_slashes(uri);
        convert_uri_to_file_name(conn, uri, path, sizeof(path));

        if (!check_authorization(conn, path)) {
                send_authorization_request(conn);
        } else if (check_embedded_authorization(conn) == FALSE) {
                /*
                 * Embedded code failed authorization. Do nothing here, since
                 * an embedded code must handle this itself by either
                 * showing proper error message, or redirecting to some
                 * sort of login page, or something else.
                 */
        } else if ((cb = find_callback(conn->ctx, FALSE, uri, -1)) != NULL) {
                if ((strcmp(ri->request_method, "POST") != 0 &&
                    strcmp(ri->request_method, "PUT") != 0) ||
                    handle_request_body(conn, NULL))
                        cb->func(conn, &conn->request_info, cb->user_data);
        } else if (strstr(path, PASSWORDS_FILE_NAME)) {
                /* Do not allow to view passwords files */
                send_error(conn, 403, "Forbidden", "Access Forbidden");
        } else if ((!strcmp(ri->request_method, "PUT") ||
            !strcmp(ri->request_method, "DELETE")) &&
            (conn->ctx->options[OPT_AUTH_PUT] == NULL ||
             !is_authorized_for_put(conn))) {
                send_authorization_request(conn);
        } else if (!strcmp(ri->request_method, "PUT")) {
                put_file(conn, path);
        } else if (!strcmp(ri->request_method, "DELETE")) {
                if (mg_remove(path) == 0)
                        send_error(conn, 200, "OK", "");
                else
                        send_error(conn, 500, http_500_error,
                            "remove(%s): %s", path, strerror(ERRNO));
        } else if (mg_stat(path, &st) != 0) {
                send_error(conn, 404, "Not Found", "%s", "File not found");
        } else if (st.is_directory && uri[strlen(uri) - 1] != '/') {
                (void) mg_printf(conn,
                    "HTTP/1.1 301 Moved Permanently\r\n"
                    "Location: %s/\r\n\r\n", uri);
        } else if (st.is_directory &&
            substitute_index_file(conn, path, sizeof(path), &st) == FALSE) {
                if (is_true(conn->ctx->options[OPT_DIR_LIST])) {
                        send_directory(conn, path);
                } else {
                        send_error(conn, 403, "Directory Listing Denied",
                            "Directory listing denied");
                }
#if !defined(NO_CGI)
        } else if (match_extension(path,
            conn->ctx->options[OPT_CGI_EXTENSIONS])) {
                if (strcmp(ri->request_method, "POST") &&
                    strcmp(ri->request_method, "GET")) {
                        send_error(conn, 501, "Not Implemented",
                            "Method %s is not implemented", ri->request_method);
                } else {
                        send_cgi(conn, path);
                }
#endif /* NO_CGI */
#if !defined(NO_SSI)
        } else if (match_extension(path,
            conn->ctx->options[OPT_SSI_EXTENSIONS])) {
                send_ssi(conn, path);
#endif /* NO_SSI */
        } else if (is_not_modified(conn, &st)) {
                send_error(conn, 304, "Not Modified", "");
        } else {
                send_file(conn, path, &st);
        }
}

static void
close_all_listening_sockets(struct mg_context *ctx)
{
        int     i;

        for (i = 0; i < ctx->num_listeners; i++)
                (void) closesocket(ctx->listeners[i].sock);
        ctx->num_listeners = 0;
}

static bool_t
set_ports_option(struct mg_context *ctx, const char *list)
{
        SOCKET          sock;
        int             is_ssl;
        struct vec      vec;
        struct socket   *listener;

        close_all_listening_sockets(ctx);
        assert(ctx->num_listeners == 0);

        while ((list = next_option(list, &vec, NULL)) != NULL) {

                is_ssl  = vec.ptr[vec.len - 1] == 's' ? TRUE : FALSE;
                listener = ctx->listeners + ctx->num_listeners;

                if (ctx->num_listeners >=
                    (int) (ARRAY_SIZE(ctx->listeners) - 1)) {
                        cry(fc(ctx), "%s", "Too many listeninig sockets");
                        return (FALSE);
                } else if ((sock = mg_open_listening_port(ctx,
                    vec.ptr, &listener->lsa)) == INVALID_SOCKET) {
                        cry(fc(ctx), "cannot bind to %.*s", vec.len, vec.ptr);
                        return (FALSE);
                } else if (is_ssl == TRUE && ctx->ssl_ctx == NULL) {
                        (void) closesocket(sock);
                        cry(fc(ctx), "cannot add SSL socket, please specify "
                            "-ssl_cert option BEFORE -ports option");
                        return (FALSE);
                } else {
                        listener->sock = sock;
                        listener->is_ssl = is_ssl;
                        ctx->num_listeners++;
                }
        }

        return (TRUE);
}

static void
log_header(const struct mg_connection *conn, const char *header, FILE *fp)
{
        const char      *header_value;

        if ((header_value = mg_get_header(conn, header)) == NULL) {
                (void) fprintf(fp, "%s", " -");
        } else {
                (void) fprintf(fp, " \"%s\"", header_value);
        }
}

static void
log_access(const struct mg_connection *conn)
{
        const struct mg_request_info *ri;
        char            date[64];

        if (conn->ctx->access_log == NULL)
                return;

        (void) strftime(date, sizeof(date), "%d/%b/%Y:%H:%M:%S %z",
            localtime(&conn->birth_time));

        ri = &conn->request_info;

        flockfile(conn->ctx->access_log);

        (void) fprintf(conn->ctx->access_log,
            "%s - %s [%s] \"%s %s HTTP/%s\" %d %" INT64_FMT,
            inet_ntoa(conn->client.rsa.u.sin.sin_addr),
            ri->remote_user == NULL ? "-" : ri->remote_user,
            date,
            ri->request_method ? ri->request_method : "-",
            ri->uri ? ri->uri : "-",
            ri->http_version,
            conn->request_info.status_code, conn->num_bytes_sent);
        log_header(conn, "Referer", conn->ctx->access_log);
        log_header(conn, "User-Agent", conn->ctx->access_log);
        (void) fputc('\n', conn->ctx->access_log);
        (void) fflush(conn->ctx->access_log);

        funlockfile(conn->ctx->access_log);
}

static bool_t
isbyte(int n) {
        return (n >= 0 && n <= 255);
}

/*
 * Verify given socket address against the ACL.
 * Return -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.
 */
static int
check_acl(struct mg_context *ctx, const char *list, const struct usa *usa)
{
        int             a, b, c, d, n, mask, allowed;
        char            flag;
        uint32_t        acl_subnet, acl_mask, remote_ip;
        struct vec      vec;

        (void) memcpy(&remote_ip, &usa->u.sin.sin_addr, sizeof(remote_ip));

        /* If any ACL is set, deny by default */
        allowed = '-';

        while ((list = next_option(list, &vec, NULL)) != NULL) {

                mask = 32;

                if (sscanf(vec.ptr, "%c%d.%d.%d.%d%n",
                    &flag, &a, &b, &c, &d, &n) != 5) {
                        cry(fc(ctx),
                            "%s: subnet must be [+|-]x.x.x.x[/x]", __func__);
                        return (-1);
                } else if (flag != '+' && flag != '-') {
                        cry(fc(ctx), "%s: flag must be + or -: [%s]",
                            __func__, vec.ptr);
                        return (-1);
                } else if (!isbyte(a)||!isbyte(b)||!isbyte(c)||!isbyte(d)) {
                        cry(fc(ctx),
                            "%s: bad ip address: [%s]", __func__, vec.ptr);
                        return (-1);
                } else if (sscanf(vec.ptr + n, "/%d", &mask) == 0) {
                        /* Do nothing, no mask specified */
                } else if (mask < 0 || mask > 32) {
                        cry(fc(ctx), "%s: bad subnet mask: %d [%s]",
                            __func__, n, vec.ptr);
                        return (-1);
                }

                acl_subnet = ((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8) | (uint32_t)d;
                acl_mask = mask ? 0xffffffffU << (32 - mask) : 0;

                if (acl_subnet == (ntohl(remote_ip) & acl_mask))
                        allowed = flag;
        }

        return (allowed == '+' ? 1 : 0);
}

static void
add_to_set(SOCKET fd, fd_set *set, int *max_fd)
{
        FD_SET(fd, set);
        if (fd > (SOCKET) *max_fd)
                *max_fd = (int) fd;
}

/*
 * Deallocate mongoose context, free up the resources
 */
static void
mg_fini(struct mg_context *ctx)
{
        int     i;

        close_all_listening_sockets(ctx);

        /* Wait until all threads finish */
        (void) pthread_mutex_lock(&ctx->thr_mutex);
        while (ctx->num_threads > 0)
                (void) pthread_cond_wait(&ctx->thr_cond, &ctx->thr_mutex);
        (void) pthread_mutex_unlock(&ctx->thr_mutex);

        /* Deallocate all registered callbacks */
        for (i = 0; i < ctx->num_callbacks; i++)
                if (ctx->callbacks[i].uri_regex != NULL)
                        free(ctx->callbacks[i].uri_regex);

        /* Deallocate all options */
        for (i = 0; i < NUM_OPTIONS; i++)
                if (ctx->options[i] != NULL)
                        free(ctx->options[i]);

        /* Close log files */
        if (ctx->access_log)
                (void) fclose(ctx->access_log);
        if (ctx->error_log)
                (void) fclose(ctx->error_log);

        /* Deallocate SSL context */
        if (ctx->ssl_ctx)
                SSL_CTX_free(ctx->ssl_ctx);

        /* Deallocate mutexes and condvars */
        for (i = 0; i < NUM_OPTIONS; i++)
                (void) pthread_mutex_destroy(&ctx->opt_mutex[i]);

        (void) pthread_mutex_destroy(&ctx->thr_mutex);
        (void) pthread_mutex_destroy(&ctx->bind_mutex);
        (void) pthread_cond_destroy(&ctx->thr_cond);
        (void) pthread_cond_destroy(&ctx->empty_cond);
        (void) pthread_cond_destroy(&ctx->full_cond);

        /* Signal mg_stop() that we're done */
        ctx->stop_flag = 2;
}

#if !defined(_WIN32)
static bool_t
set_uid_option(struct mg_context *ctx, const char *uid)
{
        struct passwd   *pw;
        int             retval = FALSE;

        if ((pw = getpwnam(uid)) == NULL)
                cry(fc(ctx), "%s: unknown user [%s]", __func__, uid);
        else if (setgid(pw->pw_gid) == -1)
                cry(fc(ctx), "%s: setgid(%s): %s",
                    __func__, uid, strerror(errno));
        else if (setuid(pw->pw_uid) == -1)
                cry(fc(ctx), "%s: setuid(%s): %s",
                    __func__, uid, strerror(errno));
        else
                retval = TRUE;

        return (retval);
}
#endif /* !_WIN32 */

#if !defined(NO_SSL)
void
mg_set_ssl_password_callback(struct mg_context *ctx, mg_spcb_t func)
{
        ctx->ssl_password_callback = func;
}

static pthread_mutex_t *ssl_mutexes;

static void
ssl_locking_callback(int mode, int mutex_num, const char *file, int line)
{
        line = 0;       /* Unused */
        file = NULL;    /* Unused */

        if (mode & CRYPTO_LOCK)
                (void) pthread_mutex_lock(&ssl_mutexes[mutex_num]);
        else
                (void) pthread_mutex_unlock(&ssl_mutexes[mutex_num]);
}

static unsigned long
ssl_id_callback(void)
{
        return ((unsigned long) pthread_self());
}

static bool_t
load_dll(struct mg_context *ctx, const char *dll_name, struct ssl_func *sw)
{
        union {void *p; void (*fp)(void);} u;
        void            *dll_handle;
        struct ssl_func *fp;

        if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
                cry(fc(ctx), "%s: cannot load %s", __func__, dll_name);
                return (FALSE);
        }

        for (fp = sw; fp->name != NULL; fp++) {
#ifdef _WIN32
                /* GetProcAddress() returns pointer to function */
                u.fp = (void (*)(void)) dlsym(dll_handle, fp->name);
#else
                /*
                 * dlsym() on UNIX returns void *.
                 * ISO C forbids casts of data pointers to function
                 * pointers. We need to use a union to make a cast.
                 */
                u.p = dlsym(dll_handle, fp->name);
#endif /* _WIN32 */
                if (u.fp == NULL) {
                        cry(fc(ctx), "%s: cannot find %s", __func__, fp->name);
                        return (FALSE);
                } else {
                        fp->ptr = u.fp;
                }
        }

        return (TRUE);
}

/*
 * Dynamically load SSL library. Set up ctx->ssl_ctx pointer.
 */
static bool_t
set_ssl_option(struct mg_context *ctx, const char *pem)
{
        SSL_CTX         *CTX;
        int             i, size, retval = FALSE;

        if (load_dll(ctx, SSL_LIB, ssl_sw) == FALSE ||
            load_dll(ctx, CRYPTO_LIB, crypto_sw) == FALSE)
                return (FALSE);

        /* Initialize SSL crap */
        SSL_library_init();

        if ((CTX = SSL_CTX_new(SSLv23_server_method())) == NULL)
                cry(fc(ctx), "SSL_CTX_new error");
        else if (ctx->ssl_password_callback != NULL)
                SSL_CTX_set_default_passwd_cb(CTX, ctx->ssl_password_callback);

        if (CTX != NULL && SSL_CTX_use_certificate_file(
            CTX, pem, SSL_FILETYPE_PEM) == 0)
                cry(fc(ctx), "%s: cannot open %s", __func__, pem);
        else if (CTX != NULL && SSL_CTX_use_PrivateKey_file(
            CTX, pem, SSL_FILETYPE_PEM) == 0)
                cry(fc(ctx), "%s: cannot open %s", NULL, pem);
        else
                retval = TRUE;

        /*
         * Initialize locking callbacks, needed for thread safety.
         * http://www.openssl.org/support/faq.html#PROG1
         */
        size = sizeof(pthread_mutex_t) * CRYPTO_num_locks();
        if ((ssl_mutexes = (pthread_mutex_t *) malloc(size)) == NULL) {
                cry(fc(ctx), "%s: cannot allocate mutexes", __func__);
                return (FALSE);
        }

        for (i = 0; i < CRYPTO_num_locks(); i++)
                pthread_mutex_init(&ssl_mutexes[i], NULL);

        CRYPTO_set_locking_callback(&ssl_locking_callback);
        CRYPTO_set_id_callback(&ssl_id_callback);

        /* Done with everything. Save the context. */
        ctx->ssl_ctx = CTX;

        return (retval);
}
#endif /* !NO_SSL */

static bool_t
open_log_file(struct mg_context *ctx, FILE **fpp, const char *path)
{
        bool_t  retval = TRUE;

        if (*fpp != NULL)
                (void) fclose(*fpp);

        if (path == NULL) {
                *fpp = NULL;
        } else if ((*fpp = mg_fopen(path, "a")) == NULL) {
                cry(fc(ctx), "%s(%s): %s", __func__, path, strerror(errno));
                retval = FALSE;
        } else {
                set_close_on_exec(fileno(*fpp));
        }

        return (retval);
}

static bool_t
set_alog_option(struct mg_context *ctx, const char *path)
{
        return (open_log_file(ctx, &ctx->access_log, path));
}

static bool_t
set_elog_option(struct mg_context *ctx, const char *path)
{
        return (open_log_file(ctx, &ctx->error_log, path));
}

static bool_t
set_gpass_option(struct mg_context *ctx, const char *path)
{
        struct mgstat   mgstat;
        ctx = NULL;
        return (mg_stat(path, &mgstat) == 0);
}

static bool_t
set_max_threads_option(struct mg_context *ctx, const char *str)
{
        ctx->max_threads = atoi(str);
        return (TRUE);
}

static bool_t
set_acl_option(struct mg_context *ctx, const char *acl)
{
        struct usa      fake;

        return (check_acl(ctx, acl, &fake) != -1);
}

static void admin_page(struct mg_connection *,
                const struct mg_request_info *, void *);
static bool_t
set_admin_uri_option(struct mg_context *ctx, const char *uri)
{
        mg_set_uri_callback(ctx, uri, &admin_page, NULL);
        return (TRUE);
}

/*
 * Check if the comma-separated list of options has a format of key-value
 * pairs: "k1=v1,k2=v2". Return FALSE if any entry has invalid key or value.
 */
static bool_t
set_kv_list_option(struct mg_context *ctx, const char *str)
{
        const char      *list;
        struct vec      key, value;

        list = str;
        while ((list = next_option(list, &key, &value)) != NULL)
                if (key.len == 0 || value.len == 0) {
                        cry(fc(ctx), "Invalid list specified: [%s], "
                            "expecting key1=value1,key2=value2,...", str);
                        return (FALSE);
                }

        return (TRUE);
}

static const struct mg_option known_options[] = {
        {"root", "\tWeb root directory", ".", OPT_ROOT, NULL},
        {"index_files", "Index files", "index.html,index.htm,index.cgi",
                OPT_INDEX_FILES, NULL},
#if !defined(NO_SSL)
        {"ssl_cert", "SSL certificate file", NULL,
                OPT_SSL_CERTIFICATE, &set_ssl_option},
#endif /* !NO_SSL */
        {"ports", "Listening ports", NULL,
                OPT_PORTS, &set_ports_option},
        {"dir_list", "Directory listing", "yes",
                OPT_DIR_LIST, NULL},
        {"protect", "URI to htpasswd mapping", NULL,
                OPT_PROTECT, &set_kv_list_option},
#if !defined(NO_CGI)
        {"cgi_ext", "CGI extensions", ".cgi,.pl,.php",
                OPT_CGI_EXTENSIONS, NULL},
        {"cgi_interp", "CGI interpreter to use with all CGI scripts", NULL,
                OPT_CGI_INTERPRETER, NULL},
        {"cgi_env", "Custom CGI enviroment variables", NULL,
                OPT_CGI_ENV, &set_kv_list_option},
#endif /* NO_CGI */
        {"ssi_ext", "SSI extensions", ".shtml,.shtm",
                OPT_SSI_EXTENSIONS, NULL},
        {"auth_realm", "Authentication domain name", "mydomain.com",
                OPT_AUTH_DOMAIN, NULL},
        {"auth_gpass", "Global passwords file", NULL,
                OPT_AUTH_GPASSWD, &set_gpass_option},
        {"auth_PUT", "PUT,DELETE auth file", NULL,
                OPT_AUTH_PUT, NULL},
#if !defined(_WIN32)
        {"uid", "\tRun as user", NULL, OPT_UID, &set_uid_option},
#endif /* !_WIN32 */
        {"access_log", "Access log file", NULL,
                OPT_ACCESS_LOG, &set_alog_option},
        {"error_log", "Error log file", NULL,
                OPT_ERROR_LOG, &set_elog_option},
        {"aliases", "Path=URI mappings", NULL,
                OPT_ALIASES, &set_kv_list_option},
        {"admin_uri", "Administration page URI", NULL,
                OPT_ADMIN_URI, &set_admin_uri_option},
        {"acl", "\tAllow/deny IP addresses/subnets", NULL,
                OPT_ACL, &set_acl_option},
        {"max_threads", "Maximum simultaneous threads to spawn", "100",
                OPT_MAX_THREADS, &set_max_threads_option},
        {"idle_time", "Time in seconds connection stays idle", "10",
                OPT_IDLE_TIME, NULL},
        {"mime_types", "Comma separated list of ext=mime_type pairs", NULL,
                OPT_MIME_TYPES, &set_kv_list_option},
        {NULL, NULL, NULL, 0, NULL}
};

static const struct mg_option *
find_opt(const char *opt_name)
{
        int     i;

        for (i = 0; known_options[i].name != NULL; i++)
                if (!strcmp(opt_name, known_options[i].name))
                        return (known_options + i);

        return (NULL);
}

int
mg_set_option(struct mg_context *ctx, const char *opt, const char *val)
{
        const struct mg_option  *option;
        int                     i, retval;

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: [%s]->[%s]", __func__, opt, val));
        if (opt != NULL && (option = find_opt(opt)) != NULL) {
                i = (int) (option - known_options);
                lock_option(ctx, i);

                if (option->setter != NULL)
                        retval = option->setter(ctx, val);
                else
                        retval = TRUE;

                /* Free old value if any */
                if (ctx->options[option->index] != NULL)
                        free(ctx->options[option->index]);

                /* Set new option value */
                ctx->options[option->index] = val ? mg_strdup(val) : NULL;
                unlock_option(ctx, i);

                if (retval == FALSE)
                        cry(fc(ctx), "%s(%s): failure", __func__, opt);
        } else {
                cry(fc(ctx), "%s: No such option: [%s]", __func__, opt);
                retval = -1;
        }

        return (retval);
}

void
mg_show_usage_string(FILE *fp)
{
        const struct mg_option  *o;

        (void) fprintf(stderr,
            "Mongoose version %s (c) Sergey Lyubka\n"
            "usage: mongoose [options] [config_file]\n", mg_version());

        fprintf(fp, "  -A <htpasswd_file> <realm> <user> <passwd>\n");

        for (o = known_options; o->name != NULL; o++) {
                (void) fprintf(fp, "  -%s\t%s", o->name, o->description);
                if (o->default_value != NULL)
                        fprintf(fp, " (default: \"%s\")", o->default_value);
                fputc('\n', fp);
        }
}

const char *
mg_get_option(const struct mg_context *ctx, const char *option_name)
{
        const struct mg_option  *option;

        if ((option = find_opt(option_name)) != NULL)
                return (ctx->options[option->index]);
        else
                return (NULL);
}

static void
admin_page(struct mg_connection *conn, const struct mg_request_info *ri,
                           void *user_data)
{
        const struct mg_option  *option;
        const char              *option_name, *option_value;

        user_data = NULL; /* Unused */

        (void) mg_printf(conn,
        "HTTP/1.1 200 OK\r\n"
                        "Content-Type: text/html\r\n\r\n"
                        "<html><body><h1>Mongoose v. %s</h1>", mg_version());

        if (!strcmp(ri->request_method, "POST")) {
                option_name = mg_get_var(conn, "o");
                option_value = mg_get_var(conn, "v");
                if (mg_set_option(conn->ctx,
                    option_name, option_value) == -1) {
                        (void) mg_printf(conn,
                            "<p style=\"background: red\">Error setting "
                            "option \"%s\"</p>",
                            option_name ? option_name : "(null)");
                } else {
                        (void) mg_printf(conn,
                            "<p style=\"color: green\">Saved: %s=%s</p>",
                            option_name, option_value ? option_value : "NULL");
                }
        }

        /* Print table with all options */
        (void) mg_printf(conn, "%s", "<table border=\"1\""
                        "<tr><th>Option</th><th>Description</th>"
                                        "<th colspan=2>Value</th></tr>");

        for (option = known_options; option->name != NULL; option++) {
                option_value = mg_get_option(conn->ctx, option->name);
                if (option_value == NULL)
                        option_value = "";
                (void) mg_printf(conn,
                    "<form method=post><tr><td>%s</td><td>%s</td>"
                    "<input type=hidden name=o value='%s'>"
                    "<td><input type=text name=v value='%s'></td>"
                    "<td><input type=submit value=save></td></form></tr>",
                    option->name, option->description,
                    option->name, option_value);
        }

        (void) mg_printf(conn, "%s", "</table></body></html>");
}

static void
reset_per_request_attributes(struct mg_connection *conn)
{
        if (conn->request_info.remote_user != NULL) {
                free((void *) conn->request_info.remote_user);
                conn->request_info.remote_user = NULL;
        }
        if (conn->free_post_data && conn->request_info.post_data != NULL) {
                free((void *) conn->request_info.post_data);
                conn->request_info.post_data = NULL;
        }
}

static void
close_socket_gracefully(struct mg_connection *conn, SOCKET sock)
{
        char    buf[BUFSIZ];
        int     n;

        /* Send FIN to the client */
        (void) shutdown(sock, SHUT_WR);
        set_non_blocking_mode(conn, sock);

        /*
         * Read and discard pending data. If we do not do that and close the
         * socket, the data in the send buffer may be discarded. This
         * behaviour is seen on Windows, when client keeps sending data
         * when server decide to close the connection; then when client
         * does recv() it gets no data back.
         */
        do {
                n = pull(NULL, sock, NULL, buf, sizeof(buf));
        } while (n > 0);

        /* Now we know that our FIN is ACK-ed, safe to close */
        (void) closesocket(sock);
}

static void
close_connection(struct mg_connection *conn)
{
        reset_per_request_attributes(conn);

        if (conn->ssl)
                SSL_free(conn->ssl);

        if (conn->client.sock != INVALID_SOCKET)
                close_socket_gracefully(conn, conn->client.sock);
}

static void
reset_connection_attributes(struct mg_connection *conn)
{
        reset_per_request_attributes(conn);
        conn->free_post_data = FALSE;
        conn->request_info.status_code = -1;
        conn->num_bytes_sent = 0;
        (void) memset(&conn->request_info, 0, sizeof(conn->request_info));
}

static void
shift_to_next(struct mg_connection *conn, char *buf, int req_len, int *nread)
{
        int64_t cl;
        int     over_len, body_len;

        cl = get_content_length(conn);
        over_len = *nread - req_len;
        assert(over_len >= 0);

        if (cl == -1) {
                body_len = 0;
        } else if (cl < (int64_t) over_len) {
                body_len = (int) cl;
        } else {
                body_len = over_len;
        }

        *nread -= req_len + body_len;
        (void) memmove(buf, buf + req_len + body_len, *nread);
}

static void
process_new_connection(struct mg_connection *conn)
{
        struct mg_request_info *ri = &conn->request_info;
        char    buf[MAX_REQUEST_SIZE];
        int     request_len, nread;

        nread = 0;
        reset_connection_attributes(conn);

        /* If next request is not pipelined, read it in */
        if ((request_len = get_request_len(buf, (size_t) nread)) == 0)
                request_len = read_request(NULL, conn->client.sock,
                    conn->ssl, buf, sizeof(buf), &nread);
        assert(nread >= request_len);

        if (request_len <= 0)
                return; /* Remote end closed the connection */

        /* 0-terminate the request: parse_request uses sscanf */
        buf[request_len - 1] = '\0';

        if (parse_http_request(buf, ri, &conn->client.rsa)) {
                if (strcmp(ri->http_version, "1.0") != 0 &&
                    strcmp(ri->http_version, "1.1") != 0) {
                        send_error(conn, 505,
                            "HTTP version not supported",
                            "%s", "Weird HTTP version");
                        log_access(conn);
                } else {
                        ri->post_data = buf + request_len;
                        ri->post_data_len = nread - request_len;
                        conn->birth_time = time(NULL);
                        analyze_request(conn);
                        log_access(conn);
                        shift_to_next(conn, buf, request_len, &nread);
                }
        } else {
                /* Do not put garbage in the access log */
                send_error(conn, 400, "Bad Request",
                    "Can not parse request: [%.*s]", nread, buf);
        }

}

/*
 * Worker threads take accepted socket from the queue
 */
static bool_t
get_socket(struct mg_context *ctx, struct socket *sp)
{
        struct timespec ts;

        (void) pthread_mutex_lock(&ctx->thr_mutex);
        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: thread %p: going idle",
            __func__, (void *) pthread_self()));

        /* If the queue is empty, wait. We're idle at this point. */
        ctx->num_idle++;
        while (ctx->sq_head == ctx->sq_tail) {
                ts.tv_nsec = 0;
                ts.tv_sec = time(NULL) + atoi(ctx->options[OPT_IDLE_TIME]) + 1;
                if (pthread_cond_timedwait(&ctx->empty_cond,
                    &ctx->thr_mutex, &ts) != 0) {
                        /* Timeout! release the mutex and return */
                        (void) pthread_mutex_unlock(&ctx->thr_mutex);
                        return (FALSE);
                }
        }
        assert(ctx->sq_head > ctx->sq_tail);

        /* We're going busy now: got a socket to process! */
        ctx->num_idle--;

        /* Copy socket from the queue and increment tail */
        *sp = ctx->queue[ctx->sq_tail % ARRAY_SIZE(ctx->queue)];
        ctx->sq_tail++;
        DEBUG_TRACE((DEBUG_MGS_PREFIX
            "%s: thread %p grabbed socket %d, going busy",
            __func__, (void *) pthread_self(), sp->sock));

        /* Wrap pointers if needed */
        while (ctx->sq_tail > (int) ARRAY_SIZE(ctx->queue)) {
                ctx->sq_tail -= ARRAY_SIZE(ctx->queue);
                ctx->sq_head -= ARRAY_SIZE(ctx->queue);
        }

        pthread_cond_signal(&ctx->full_cond);
        (void) pthread_mutex_unlock(&ctx->thr_mutex);

        return (TRUE);
}

static void
worker_thread(struct mg_context *ctx)
{
        struct mg_connection    conn;

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: thread %p starting",
            __func__, (void *) pthread_self()));

        (void) memset(&conn, 0, sizeof(conn));

        while (get_socket(ctx, &conn.client) == TRUE) {
                conn.birth_time = time(NULL);
                conn.ctx = ctx;

                if (conn.client.is_ssl &&
                    (conn.ssl = SSL_new(conn.ctx->ssl_ctx)) == NULL) {
                        cry(&conn, "%s: SSL_new: %d", __func__, ERRNO);
                } else if (conn.client.is_ssl &&
                    SSL_set_fd(conn.ssl, conn.client.sock) != 1) {
                        cry(&conn, "%s: SSL_set_fd: %d", __func__, ERRNO);
                } else if (conn.client.is_ssl && SSL_accept(conn.ssl) != 1) {
                        cry(&conn, "%s: SSL handshake error", __func__);
                } else {
                        process_new_connection(&conn);
                }

                close_connection(&conn);
        }

        /* Signal master that we're done with connection and exiting */
        pthread_mutex_lock(&ctx->thr_mutex);
        ctx->num_threads--;
        ctx->num_idle--;
        pthread_cond_signal(&ctx->thr_cond);
        assert(ctx->num_threads >= 0);
        pthread_mutex_unlock(&ctx->thr_mutex);

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: thread %p exiting",
            __func__, (void *) pthread_self()));
}

/*
 * Master thread adds accepted socket to a queue
 */
static void
put_socket(struct mg_context *ctx, const struct socket *sp)
{
        (void) pthread_mutex_lock(&ctx->thr_mutex);

        /* If the queue is full, wait */
        while (ctx->sq_head - ctx->sq_tail >= (int) ARRAY_SIZE(ctx->queue))
                (void) pthread_cond_wait(&ctx->full_cond, &ctx->thr_mutex);
        assert(ctx->sq_head - ctx->sq_tail < (int) ARRAY_SIZE(ctx->queue));

        /* Copy socket to the queue and increment head */
        ctx->queue[ctx->sq_head % ARRAY_SIZE(ctx->queue)] = *sp;
        ctx->sq_head++;
        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: queued socket %d",
            __func__, sp->sock));

        /* If there are no idle threads, start one */
        if (ctx->num_idle == 0 && ctx->num_threads < ctx->max_threads) {
                if (start_thread(ctx,
                    (mg_thread_func_t) worker_thread, ctx) != 0)
                        cry(fc(ctx), "Cannot start thread: %d", ERRNO);
                else
                        ctx->num_threads++;
        }

        pthread_cond_signal(&ctx->empty_cond);
        (void) pthread_mutex_unlock(&ctx->thr_mutex);
}

static void
accept_new_connection(const struct socket *listener, struct mg_context *ctx)
{
        struct socket   accepted;

        accepted.rsa.len = sizeof(accepted.rsa.u.sin);
        accepted.lsa = listener->lsa;
        if ((accepted.sock = accept(listener->sock,
            &accepted.rsa.u.sa, &accepted.rsa.len)) == INVALID_SOCKET)
                return;

        lock_option(ctx, OPT_ACL);
        if (ctx->options[OPT_ACL] != NULL &&
            !check_acl(ctx, ctx->options[OPT_ACL], &accepted.rsa)) {
                cry(fc(ctx), "%s: %s is not allowed to connect",
                    __func__, inet_ntoa(accepted.rsa.u.sin.sin_addr));
                (void) closesocket(accepted.sock);
                unlock_option(ctx, OPT_ACL);
                return;
        }
        unlock_option(ctx, OPT_ACL);

        /* Put accepted socket structure into the queue */
        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: accepted socket %d",
            __func__, accepted.sock));
        accepted.is_ssl = listener->is_ssl;
        put_socket(ctx, &accepted);
}

static void
master_thread(struct mg_context *ctx)
{
        fd_set          read_set;
        struct timeval  tv;
        int             i, max_fd;

        while (ctx->stop_flag == 0) {
                FD_ZERO(&read_set);
                max_fd = -1;

                /* Add listening sockets to the read set */
                lock_option(ctx, OPT_PORTS);
                for (i = 0; i < ctx->num_listeners; i++)
                        add_to_set(ctx->listeners[i].sock, &read_set, &max_fd);
                unlock_option(ctx, OPT_PORTS);

                tv.tv_sec = 1;
                tv.tv_usec = 0;

                if (select(max_fd + 1, &read_set, NULL, NULL, &tv) < 0) {
#ifdef _WIN32
                        /*
                         * On windows, if read_set and write_set are empty,
                         * select() returns "Invalid parameter" error
                         * (at least on my Windows XP Pro). So in this case,
                         * we sleep here.
                         */
                        sleep(1);
#endif /* _WIN32 */
                } else {
                        lock_option(ctx, OPT_PORTS);
                        for (i = 0; i < ctx->num_listeners; i++)
                                if (FD_ISSET(ctx->listeners[i].sock, &read_set))
                                        accept_new_connection(
                                            ctx->listeners + i, ctx);
                        unlock_option(ctx, OPT_PORTS);
                }
        }

        /* Stop signal received: somebody called mg_stop. Quit. */
        mg_fini(ctx);
}

void
mg_stop(struct mg_context *ctx)
{
        ctx->stop_flag = 1;

        /* Wait until mg_fini() stops */
        while (ctx->stop_flag != 2)
                (void) sleep(1);

        assert(ctx->num_threads == 0);
        free(ctx);

#if defined(_WIN32)
        (void) WSACleanup();
#endif /* _WIN32 */
}

struct mg_context *
mg_start(void)
{
        struct mg_context       *ctx;
        const struct mg_option  *option;
        int                     i;

#if defined(_WIN32)
        WSADATA data;
        WSAStartup(MAKEWORD(2,2), &data);
#endif /* _WIN32 */

        if ((ctx = (struct mg_context *) calloc(1, sizeof(*ctx))) == NULL) {
                cry(fc(ctx), "cannot allocate mongoose context");
                return (NULL);
        }

        ctx->error_log = stderr;
        mg_set_log_callback(ctx, builtin_error_log);

        /* Initialize options. First pass: set default option values */
        for (option = known_options; option->name != NULL; option++)
                ctx->options[option->index] = option->default_value == NULL ?
                        NULL : mg_strdup(option->default_value);

        /* Call setter functions */
        for (option = known_options; option->name != NULL; option++)
                if (option->setter != NULL &&
                    ctx->options[option->index] != NULL)
                        if (option->setter(ctx,
                            ctx->options[option->index]) == FALSE) {
                                mg_fini(ctx);
                                return (NULL);
                        }

        DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: root [%s]",
            __func__, ctx->options[OPT_ROOT]));

#if !defined(_WIN32)
        /*
         * Ignore SIGPIPE signal, so if browser cancels the request, it
         * won't kill the whole process.
         */
        (void) signal(SIGPIPE, SIG_IGN);
#endif /* _WIN32 */

        /* Initialize options mutexes */
        for (i = 0; i < NUM_OPTIONS; i++)
                (void) pthread_mutex_init(&ctx->opt_mutex[i], NULL);

        (void) pthread_mutex_init(&ctx->thr_mutex, NULL);
        (void) pthread_mutex_init(&ctx->bind_mutex, NULL);
        (void) pthread_cond_init(&ctx->thr_cond, NULL);
        (void) pthread_cond_init(&ctx->empty_cond, NULL);
        (void) pthread_cond_init(&ctx->full_cond, NULL);

        /* Start master (listening) thread */
        start_thread(ctx, (mg_thread_func_t) master_thread, ctx);

        return (ctx);
}