source: rtems-libbsd/rtemsbsd/pppd/utils.c @ f0aaa04

/*
 * utils.c - various utility functions used in pppd.
 *
 * Copyright (c) 1999 The Australian National University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the Australian National University.  The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#define RCSID   "$Id$"

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <syslog.h>
#include <pwd.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifdef SVR4
#include <sys/mkdev.h>
#endif

#include "pppd.h"

static const char rcsid[] = RCSID;

static void pr_log(void *, char *, ...);
static void logit(int, char *, va_list);
static void vslp_printer(void *, char *, ...);
static void format_packet(u_char *, int, void (*) (void *, char *, ...),
                               void *);

struct buffer_info {
    char *ptr;
    int len;
};

/*
 * slprintf - format a message into a buffer.  Like sprintf except we
 * also specify the length of the output buffer, and we handle
 * %r (recursive format), %m (error message), %v (visible string),
 * %q (quoted string), %t (current time) and %I (IP address) formats.
 * Doesn't do floating-point formats.
 * Returns the number of chars put into buf.
 */
int
slprintf __V((char *buf, int buflen, char *fmt, ...))
{
    va_list args;
    int n;

#if defined(__STDC__)
    va_start(args, fmt);
#else
    char *buf;
    int buflen;
    char *fmt;
    va_start(args);
    buf = va_arg(args, char *);
    buflen = va_arg(args, int);
    fmt = va_arg(args, char *);
#endif
    n = vslprintf(buf, buflen, fmt, args);
    va_end(args);
    return n;
}

/*
 * vslprintf - like slprintf, takes a va_list instead of a list of args.
 */
#define OUTCHAR(c)      (buflen > 0? (--buflen, *buf++ = (c)): 0)

int
vslprintf(
    char *buf,
    int buflen,
    char *fmt,
    va_list args)
{
    int c, i, n;
    int width, prec, fillch;
    int base, len, neg, quoted;
    uintptr_t val = 0;
    char *str, *f, *buf0;
    unsigned char *p;
    char num[32];
    time_t t;
    uint32_t ip;
    static char hexchars[] = "0123456789abcdef";
    struct buffer_info bufinfo;

    buf0 = buf;
    --buflen;
    while (buflen > 0) {
        for (f = fmt; *f != '%' && *f != 0; ++f)
            ;
        if (f > fmt) {
            len = f - fmt;
            if (len > buflen)
                len = buflen;
            memcpy(buf, fmt, len);
            buf += len;
            buflen -= len;
            fmt = f;
        }
        if (*fmt == 0)
            break;
        c = *++fmt;
        width = 0;
        prec = -1;
        fillch = ' ';
        if (c == '0') {
            fillch = '0';
            c = *++fmt;
        }
        if (c == '*') {
            width = va_arg(args, int);
            c = *++fmt;
        } else {
            while (isdigit(c)) {
                width = width * 10 + c - '0';
                c = *++fmt;
            }
        }
        if (c == '.') {
            c = *++fmt;
            if (c == '*') {
                prec = va_arg(args, int);
                c = *++fmt;
            } else {
                prec = 0;
                while (isdigit(c)) {
                    prec = prec * 10 + c - '0';
                    c = *++fmt;
                }
            }
        }
        str = 0;
        base = 0;
        neg = 0;
        ++fmt;
        switch (c) {
        case 'd':
            i = va_arg(args, int);
            if (i < 0) {
                neg = 1;
                val = -i;
            } else
                val = i;
            base = 10;
            break;
        case 'o':
            val = va_arg(args, unsigned int);
            base = 8;
            break;
        case 'x':
        case 'X':
            val = va_arg(args, unsigned int);
            base = 16;
            break;
        case 'p':
            val = (uintptr_t) va_arg(args, void *);
            base = 16;
            neg = 2;
            break;
        case 's':
            str = va_arg(args, char *);
            break;
        case 'c':
            num[0] = va_arg(args, int);
            num[1] = 0;
            str = num;
            break;
        case 'm':
            str = strerror(errno);
            break;
        case 'I':
            ip = va_arg(args, uint32_t);
            ip = ntohl(ip);
            slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
                     (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
            str = num;
            break;
        case 'r':
            f = va_arg(args, char *);
#if !defined(__PPC__)
            n = vslprintf(buf, buflen + 1, f, va_arg(args, va_list));
#else
            /* HACK: On the powerpc, a va_list is an array of 1 structure */
            n = vslprintf(buf, buflen + 1, f, va_arg(args, void *));
#endif
            buf += n;
            buflen -= n;
            continue;
        case 't':
            time(&t);
            str = ctime(&t);
            str += 4;           /* chop off the day name */
            str[15] = 0;        /* chop off year and newline */
            break;
        case 'v':               /* "visible" string */
        case 'q':               /* quoted string */
            quoted = c == 'q';
            p = va_arg(args, unsigned char *);
            if (fillch == '0' && prec >= 0) {
                n = prec;
            } else {
                n = strlen((char *)p);
                if (prec >= 0 && n > prec)
                    n = prec;
            }
            while (n > 0 && buflen > 0) {
                c = *p++;
                --n;
                if (!quoted && c >= 0x80) {
                    OUTCHAR('M');
                    OUTCHAR('-');
                    c -= 0x80;
                }
                if (quoted && (c == '"' || c == '\\'))
                    OUTCHAR('\\');
                if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
                    if (quoted) {
                        OUTCHAR('\\');
                        switch (c) {
                        case '\t':      OUTCHAR('t');   break;
                        case '\n':      OUTCHAR('n');   break;
                        case '\b':      OUTCHAR('b');   break;
                        case '\f':      OUTCHAR('f');   break;
                        default:
                            OUTCHAR('x');
                            OUTCHAR(hexchars[c >> 4]);
                            OUTCHAR(hexchars[c & 0xf]);
                        }
                    } else {
                        if (c == '\t')
                            OUTCHAR(c);
                        else {
                            OUTCHAR('^');
                            OUTCHAR(c ^ 0x40);
                        }
                    }
                } else
                    OUTCHAR(c);
            }
            continue;
        case 'P':               /* print PPP packet */
            bufinfo.ptr = buf;
            bufinfo.len = buflen + 1;
            p = va_arg(args, unsigned char *);
            n = va_arg(args, int);
            format_packet(p, n, vslp_printer, &bufinfo);
            buf = bufinfo.ptr;
            buflen = bufinfo.len - 1;
            continue;
        case 'B':
            p = va_arg(args, unsigned char *);
            for (n = prec; n > 0; --n) {
                c = *p++;
                if (fillch == ' ')
                    OUTCHAR(' ');
                OUTCHAR(hexchars[(c >> 4) & 0xf]);
                OUTCHAR(hexchars[c & 0xf]);
            }
            continue;
        default:
            *buf++ = '%';
            if (c != '%')
                --fmt;          /* so %z outputs %z etc. */
            --buflen;
            continue;
        }
        if (base != 0) {
            str = num + sizeof(num);
            *--str = 0;
            while (str > num + neg) {
                *--str = hexchars[val % base];
                val = val / base;
                if (--prec <= 0 && val == 0)
                    break;
            }
            switch (neg) {
            case 1:
                *--str = '-';
                break;
            case 2:
                *--str = 'x';
                *--str = '0';
                break;
            }
            len = num + sizeof(num) - 1 - str;
        } else {
            len = strlen(str);
            if (prec >= 0 && len > prec)
                len = prec;
        }
        if (width > 0) {
            if (width > buflen)
                width = buflen;
            if ((n = width - len) > 0) {
                buflen -= n;
                for (; n > 0; --n)
                    *buf++ = fillch;
            }
        }
        if (len > buflen)
            len = buflen;
        memcpy(buf, str, len);
        buf += len;
        buflen -= len;
    }
    *buf = 0;
    return buf - buf0;
}

/*
 * vslp_printer - used in processing a %P format
 */
static void
vslp_printer __V((void *arg, char *fmt, ...))
{
    int n;
    va_list pvar;
    struct buffer_info *bi;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    void *arg;
    char *fmt;
    va_start(pvar);
    arg = va_arg(pvar, void *);
    fmt = va_arg(pvar, char *);
#endif

    bi = (struct buffer_info *) arg;
    n = vslprintf(bi->ptr, bi->len, fmt, pvar);
    va_end(pvar);

    bi->ptr += n;
    bi->len -= n;
}

/*
 * log_packet - format a packet and log it.
 */

char line[256];                 /* line to be logged accumulated here */
char *linep;

void
log_packet(
    u_char *p,
    int len,
    char *prefix,
    int level)
{
    strlcpy(line, prefix, sizeof(line));
    linep = line + strlen(line);
    format_packet(p, len, pr_log, NULL);
}

/*
 * format_packet - make a readable representation of a packet,
 * calling `printer(arg, format, ...)' to output it.
 */
static void
format_packet(
    u_char *p,
    int len,
    void (*printer)(void *, char *, ...),
    void *arg)
{
    int i, n;
    u_short proto;
    struct protent *protp;

    if (len >= PPP_HDRLEN && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
        p += 2;
        GETSHORT(proto, p);
        len -= PPP_HDRLEN;
        for (i = 0; (protp = protocols[i]) != NULL; ++i)
            if (proto == protp->protocol)
                break;
        if (protp != NULL) {
            printer(arg, "[%s", protp->name);
            n = (*protp->printpkt)(p, len, printer, arg);
            printer(arg, "]");
            p += n;
            len -= n;
        } else {
            for (i = 0; (protp = protocols[i]) != NULL; ++i)
                if (proto == (protp->protocol & ~0x8000))
                    break;
            if (protp != 0 && protp->data_name != 0) {
                printer(arg, "[%s data]", protp->data_name);
                if (len > 8)
                    printer(arg, "%.8B ...", p);
                else
                    printer(arg, "%.*B", len, p);
                len = 0;
            } else
                printer(arg, "[proto=0x%x]", proto);
        }
    }

    if (len > 32)
        printer(arg, "%.32B ...", p);
    else
        printer(arg, "%.*B", len, p);
}

static void
pr_log __V((void *arg, char *fmt, ...))
{
    int n;
    va_list pvar;
    char buf[256];

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    void *arg;
    char *fmt;
    va_start(pvar);
    arg = va_arg(pvar, void *);
    fmt = va_arg(pvar, char *);
#endif

    n = vslprintf(buf, sizeof(buf), fmt, pvar);
    va_end(pvar);

    if (linep + n + 1 > line + sizeof(line)) {
        linep = line;
    }
    strlcpy(linep, buf, line + sizeof(line) - linep);
    linep += n;
}

/*
 * print_string - print a readable representation of a string using
 * printer.
 */
void
print_string(
    void *p_arg,
    int len,
    void (*printer)(void *, char *, ...),
    void *arg)
{
    int c;
    unsigned char *p = (unsigned char *)p_arg;

    printer(arg, "\"");
    for (; len > 0; --len) {
        c = *p++;
        if (' ' <= c && c <= '~') {
            if (c == '\\' || c == '"')
                printer(arg, "\\");
            printer(arg, "%c", c);
        } else {
            switch (c) {
            case '\n':
                printer(arg, "\\n");
                break;
            case '\r':
                printer(arg, "\\r");
                break;
            case '\t':
                printer(arg, "\\t");
                break;
            default:
                printer(arg, "\\%.3o", c);
            }
        }
    }
    printer(arg, "\"");
}

/*
 * logit - does the hard work for fatal et al.
 */
static void
logit(
    int level,
    char *fmt,
    va_list args)
{
    int n;
    char buf[256];

    n = vslprintf(buf, sizeof(buf), fmt, args);
/*    if (log_to_fd >= 0 && (level != LOG_DEBUG || debug)) { */
    if (log_to_fd >= 0 && (debug)) {
        if (buf[n-1] != '\n')
            buf[n++] = '\n';
        if (write(log_to_fd, buf, n) != n)
            log_to_fd = -1;
    }
}

/*
 * fatal - log an error message and die horribly.
 */
void
pppd_fatal __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_ERR, fmt, pvar);
    va_end(pvar);

    die(1);                     /* as promised */
}

/*
 * error - log an error message.
 */
void
pppd_error __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_ERR, fmt, pvar);
    va_end(pvar);
}

/*
 * warn - log a warning message.
 */
void
pppd_warn __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_WARNING, fmt, pvar);
    va_end(pvar);
}

/*
 * notice - log a notice-level message.
 */
void
pppd_notice __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_NOTICE, fmt, pvar);
    va_end(pvar);
}

/*
 * info - log an informational message.
 */
void
pppd_info __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_INFO, fmt, pvar);
    va_end(pvar);
}

/*
 * dbglog - log a debug message.
 */
void
pppd_dbglog __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_DEBUG, fmt, pvar);
    va_end(pvar);
}

/* Procedures for locking the serial device using a lock file. */
#ifndef LOCK_DIR
#ifdef _linux_
#define LOCK_DIR        "/var/lock"
#else
#ifdef SVR4
#define LOCK_DIR        "/var/spool/locks"
#else
#define LOCK_DIR        "/var/spool/lock"
#endif
#endif
#endif /* LOCK_DIR */

static char lock_file[MAXPATHLEN];

/*
 * lock - create a lock file for the named device
 */
int
lock(char *dev)
{
#ifdef LOCKLIB
    int result;

    result = mklock (dev, (void *) 0);
    if (result == 0) {
        strlcpy(lock_file, sizeof(lock_file), dev);
        return 0;
    }

    if (result > 0)
        notice("Device %s is locked by pid %d", dev, result);
    else
        error("Can't create lock file %s", lock_file);
    return -1;

#else /* LOCKLIB */

    char lock_buffer[12];
    int fd, pid, n;

#ifdef SVR4
    struct stat sbuf;

    if (stat(dev, &sbuf) < 0) {
        error("Can't get device number for %s: %m", dev);
        return -1;
    }
    if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
        error("Can't lock %s: not a character device", dev);
        return -1;
    }
    slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
             LOCK_DIR, major(sbuf.st_dev),
             major(sbuf.st_rdev), minor(sbuf.st_rdev));
#else
    char *p;

    if ((p = strrchr(dev, '/')) != NULL)
        dev = p + 1;
    slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
#endif

    while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
        if (errno != EEXIST) {
            error("Can't create lock file %s: %m", lock_file);
            break;
        }

        /* Read the lock file to find out who has the device locked. */
        fd = open(lock_file, O_RDONLY, 0);
        if (fd < 0) {
            if (errno == ENOENT) /* This is just a timing problem. */
                continue;
            error("Can't open existing lock file %s: %m", lock_file);
            break;
        }
#ifndef LOCK_BINARY
        n = read(fd, lock_buffer, 11);
#else
        n = read(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
        close(fd);
        fd = -1;
        if (n <= 0) {
            error("Can't read pid from lock file %s", lock_file);
            break;
        }

        /* See if the process still exists. */
#ifndef LOCK_BINARY
        lock_buffer[n] = 0;
        pid = atoi(lock_buffer);
#endif /* LOCK_BINARY */
        if (pid == getpid())
            return 1;           /* somebody else locked it for us */
        if (pid == 0
            || (kill(pid, 0) == -1 && errno == ESRCH)) {
            if (unlink (lock_file) == 0) {
                notice("Removed stale lock on %s (pid %d)", dev, pid);
                continue;
            }
            warn("Couldn't remove stale lock on %s", dev);
        } else
            notice("Device %s is locked by pid %d", dev, pid);
        break;
    }

    if (fd < 0) {
        lock_file[0] = 0;
        return -1;
    }

    pid = getpid();
#ifndef LOCK_BINARY
    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof (pid));
#endif
    close(fd);
    return 0;

#endif
}

/*
 * relock - called to update our lockfile when we are about to detach,
 * thus changing our pid (we fork, the child carries on, and the parent dies).
 * Note that this is called by the parent, with pid equal to the pid
 * of the child.  This avoids a potential race which would exist if
 * we had the child rewrite the lockfile (the parent might die first,
 * and another process could think the lock was stale if it checked
 * between when the parent died and the child rewrote the lockfile).
 */
int
relock(int pid)
{
#ifdef LOCKLIB
    /* XXX is there a way to do this? */
    return -1;
#else /* LOCKLIB */

    int fd;
    char lock_buffer[12];

    if (lock_file[0] == 0)
        return -1;
    fd = open(lock_file, O_WRONLY, 0);
    if (fd < 0) {
        error("Couldn't reopen lock file %s: %m", lock_file);
        lock_file[0] = 0;
        return -1;
    }

#ifndef LOCK_BINARY
    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
    close(fd);
    return 0;

#endif /* LOCKLIB */
}

/*
 * unlock - remove our lockfile
 */
void
unlock(void)
{
    if (lock_file[0]) {
#ifdef LOCKLIB
        (void) rmlock(lock_file, (void *) 0);
#else
        unlink(lock_file);
#endif
        lock_file[0] = 0;
    }
}