source: rtems-libbsd/services/librpc/src/rpc/svc_udp.c @ e599318

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 *
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 *
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 *
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 *
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 *
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)svc_udp.c 1.24 87/08/11 Copyr 1984 Sun Micro";*/
/*static char *sccsid = "from: @(#)svc_udp.c    2.2 88/07/29 4.0 RPCSRC";*/
static char *rcsid = "$FreeBSD: src/lib/libc/rpc/svc_udp.c,v 1.13 2000/01/27 23:06:41 jasone Exp $";
#endif

/*
 * svc_udp.c,
 * Server side for UDP/IP based RPC.  (Does some caching in the hopes of
 * achieving execute-at-most-once semantics.)
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 */

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

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <rpc/rpc.h>
#include <sys/socket.h>
#include <errno.h>

#define rpc_buffer(xprt) ((xprt)->xp_p1)
#define MAX(a, b)     ((a > b) ? a : b)

static bool_t           svcudp_recv(SVCXPRT *xprt, struct rpc_msg *msg);
static bool_t           svcudp_reply(SVCXPRT *xprt, struct rpc_msg *msg);
static enum xprt_stat   svcudp_stat(SVCXPRT *xprt);
static bool_t           svcudp_getargs(SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr);
static bool_t           svcudp_freeargs(SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr);
static void             svcudp_destroy(SVCXPRT *xprt);
static void             cache_set (SVCXPRT *, u_long);
static int              cache_get (SVCXPRT *, struct rpc_msg *, char **, u_long *);

static struct xp_ops svcudp_op = {
        svcudp_recv,
        svcudp_stat,
        svcudp_getargs,
        svcudp_reply,
        svcudp_freeargs,
        svcudp_destroy
};

/*
 * kept in xprt->xp_p2
 */
struct svcudp_data {
        u_int   su_iosz;        /* byte size of send.recv buffer */
        u_long  su_xid;         /* transaction id */
        XDR     su_xdrs;        /* XDR handle */
        char    su_verfbody[MAX_AUTH_BYTES];    /* verifier body */
        char *  su_cache;       /* cached data, NULL if no cache */
};
#define su_data(xprt)   ((struct svcudp_data *)(xprt->xp_p2))

/*
 * Usage:
 *      xprt = svcudp_create(sock);
 *
 * If sock<0 then a socket is created, else sock is used.
 * If the socket, sock is not bound to a port then svcudp_create
 * binds it to an arbitrary port.  In any (successful) case,
 * xprt->xp_fd is the registered socket number and xprt->xp_port is the
 * associated port number.
 * Once *xprt is initialized, it is registered as a transporter;
 * see (svc.h, xprt_register).
 * The routines returns NULL if a problem occurred.
 */
SVCXPRT *
svcudp_bufcreate(
        int sock,
        u_int sendsz,
        u_int recvsz )
{
        bool_t madesock = FALSE;
        register SVCXPRT *xprt;
        register struct svcudp_data *su;
        struct sockaddr_in addr;
        socklen_t len = sizeof(struct sockaddr_in);

        if (sock == RPC_ANYSOCK) {
                if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
                        perror("svcudp_create: socket creation problem");
                        return ((SVCXPRT *)NULL);
                }
                madesock = TRUE;
        }
        memset((char *)&addr, 0, sizeof (addr));
        addr.sin_len = sizeof(struct sockaddr_in);
        addr.sin_family = AF_INET;
        if (bindresvport(sock, &addr)) {
                addr.sin_port = 0;
                (void)bind(sock, (struct sockaddr *)&addr, len);
        }
        if (getsockname(sock, (struct sockaddr *)&addr, &len) != 0) {
                perror("svcudp_create - cannot getsockname");
                if (madesock)
                        (void)_RPC_close(sock);
                return ((SVCXPRT *)NULL);
        }
        xprt = (SVCXPRT *)mem_alloc(sizeof(SVCXPRT));
        if (xprt == NULL) {
                (void)fprintf(stderr, "svcudp_create: out of memory\n");
                return (NULL);
        }
        su = (struct svcudp_data *)mem_alloc(sizeof(*su));
        if (su == NULL) {
                (void)fprintf(stderr, "svcudp_create: out of memory\n");
                return (NULL);
        }
        su->su_iosz = ((MAX(sendsz, recvsz) + 3) / 4) * 4;
        if ((rpc_buffer(xprt) = mem_alloc(su->su_iosz)) == NULL) {
                (void)fprintf(stderr, "svcudp_create: out of memory\n");
                return (NULL);
        }
        xdrmem_create(
            &(su->su_xdrs), rpc_buffer(xprt), su->su_iosz, XDR_DECODE);
        su->su_cache = NULL;
        xprt->xp_p2 = (caddr_t)su;
        xprt->xp_verf.oa_base = su->su_verfbody;
        xprt->xp_ops = &svcudp_op;
        xprt->xp_port = ntohs(addr.sin_port);
        xprt->xp_fd = sock;
        xprt_register(xprt);
        return (xprt);
}

SVCXPRT *
svcudp_create(
        int sock)
{

        return(svcudp_bufcreate(sock, UDPMSGSIZE, UDPMSGSIZE));
}

static enum xprt_stat
svcudp_stat(
        SVCXPRT *xprt)
{

        return (XPRT_IDLE);
}

static bool_t
svcudp_recv(
        SVCXPRT *xprt,
        struct rpc_msg *msg)
{
        register struct svcudp_data *su = su_data(xprt);
        register XDR *xdrs = &(su->su_xdrs);
        register int rlen;
        char *reply;
        u_long replylen;

    again:
        xprt->xp_addrlen = sizeof(struct sockaddr_in);
        rlen = recvfrom(xprt->xp_fd, rpc_buffer(xprt), (int) su->su_iosz,
            0, (struct sockaddr *)&(xprt->xp_raddr), &(xprt->xp_addrlen));
        if (rlen == -1 && errno == EINTR)
                goto again;
        if (rlen == -1 || rlen < 4*sizeof(u_int32_t))
                return (FALSE);
        xdrs->x_op = XDR_DECODE;
        XDR_SETPOS(xdrs, 0);
        if (! xdr_callmsg(xdrs, msg))
                return (FALSE);
        su->su_xid = msg->rm_xid;
        if (su->su_cache != NULL) {
                if (cache_get(xprt, msg, &reply, &replylen)) {
                        (void) sendto(xprt->xp_fd, reply, (int) replylen, 0,
                          (struct sockaddr *) &xprt->xp_raddr, xprt->xp_addrlen);
                        return (TRUE);
                }
        }
        return (TRUE);
}

static bool_t
svcudp_reply(
        SVCXPRT *xprt,
        struct rpc_msg *msg)
{
        register struct svcudp_data *su = su_data(xprt);
        register XDR *xdrs = &(su->su_xdrs);
        register int slen;
        register bool_t stat = FALSE;

        xdrs->x_op = XDR_ENCODE;
        XDR_SETPOS(xdrs, 0);
        msg->rm_xid = su->su_xid;
        if (xdr_replymsg(xdrs, msg)) {
                slen = (int)XDR_GETPOS(xdrs);
                if (sendto(xprt->xp_fd, rpc_buffer(xprt), slen, 0,
                    (struct sockaddr *)&(xprt->xp_raddr), xprt->xp_addrlen)
                    == slen) {
                        stat = TRUE;
                        if (su->su_cache && slen >= 0) {
                                cache_set(xprt, (u_long) slen);
                        }
                }
        }
        return (stat);
}

static bool_t
svcudp_getargs(
        SVCXPRT *xprt,
        xdrproc_t xdr_args,
        caddr_t args_ptr)
{

        return ((*xdr_args)(&(su_data(xprt)->su_xdrs), args_ptr));
}

static bool_t
svcudp_freeargs(
        SVCXPRT *xprt,
        xdrproc_t xdr_args,
        caddr_t args_ptr)
{
        register XDR *xdrs = &(su_data(xprt)->su_xdrs);

        xdrs->x_op = XDR_FREE;
        return ((*xdr_args)(xdrs, args_ptr));
}

static void
svcudp_destroy(
        SVCXPRT *xprt)
{
        register struct svcudp_data *su = su_data(xprt);

        xprt_unregister(xprt);
        (void)_RPC_close(xprt->xp_fd);
        XDR_DESTROY(&(su->su_xdrs));
        mem_free(rpc_buffer(xprt), su->su_iosz);
        mem_free((caddr_t)su, sizeof(struct svcudp_data));
        mem_free((caddr_t)xprt, sizeof(SVCXPRT));
}


/***********this could be a separate file*********************/

/*
 * Fifo cache for udp server
 * Copies pointers to reply buffers into fifo cache
 * Buffers are sent again if retransmissions are detected.
 */

#define SPARSENESS 4    /* 75% sparse */

#define CACHE_PERROR(msg)       \
        (void) fprintf(stderr,"%s\n", msg)

#define ALLOC(type, size)       \
        (type *) mem_alloc((unsigned) (sizeof(type) * (size)))

#define BZERO(addr, type, size)  \
        memset((char *) addr, 0, sizeof(type) * (int) (size))

/*
 * An entry in the cache
 */
typedef struct cache_node *cache_ptr;
struct cache_node {
        /*
         * Index into cache is xid, proc, vers, prog and address
         */
        u_long cache_xid;
        u_long cache_proc;
        u_long cache_vers;
        u_long cache_prog;
        struct sockaddr_in cache_addr;
        /*
         * The cached reply and length
         */
        char * cache_reply;
        u_long cache_replylen;
        /*
         * Next node on the list, if there is a collision
         */
        cache_ptr cache_next;
};



/*
 * The entire cache
 */
struct udp_cache {
        u_long uc_size;         /* size of cache */
        cache_ptr *uc_entries;  /* hash table of entries in cache */
        cache_ptr *uc_fifo;     /* fifo list of entries in cache */
        u_long uc_nextvictim;   /* points to next victim in fifo list */
        u_long uc_prog;         /* saved program number */
        u_long uc_vers;         /* saved version number */
        u_long uc_proc;         /* saved procedure number */
        struct sockaddr_in uc_addr; /* saved caller's address */
};


/*
 * the hashing function
 */
#define CACHE_LOC(transp, xid)  \
 (xid % (SPARSENESS*((struct udp_cache *) su_data(transp)->su_cache)->uc_size))


/*
 * Enable use of the cache.
 * Note: there is no disable.
 */
int svcudp_enablecache(
        SVCXPRT *transp,
        u_long size)
{
        struct svcudp_data *su = su_data(transp);
        struct udp_cache *uc;

        if (su->su_cache != NULL) {
                CACHE_PERROR("enablecache: cache already enabled");
                return(0);
        }
        uc = ALLOC(struct udp_cache, 1);
        if (uc == NULL) {
                CACHE_PERROR("enablecache: could not allocate cache");
                return(0);
        }
        uc->uc_size = size;
        uc->uc_nextvictim = 0;
        uc->uc_entries = ALLOC(cache_ptr, size * SPARSENESS);
        if (uc->uc_entries == NULL) {
                CACHE_PERROR("enablecache: could not allocate cache data");
                return(0);
        }
        BZERO(uc->uc_entries, cache_ptr, size * SPARSENESS);
        uc->uc_fifo = ALLOC(cache_ptr, size);
        if (uc->uc_fifo == NULL) {
                CACHE_PERROR("enablecache: could not allocate cache fifo");
                return(0);
        }
        BZERO(uc->uc_fifo, cache_ptr, size);
        su->su_cache = (char *) uc;
        return(1);
}


/*
 * Set an entry in the cache
 */
static void
cache_set(
        SVCXPRT *xprt,
        u_long replylen)
{
        register cache_ptr victim;
        register cache_ptr *vicp;
        register struct svcudp_data *su = su_data(xprt);
        struct udp_cache *uc = (struct udp_cache *) su->su_cache;
        u_int loc;
        char *newbuf;

        /*
         * Find space for the new entry, either by
         * reusing an old entry, or by mallocing a new one
         */
        victim = uc->uc_fifo[uc->uc_nextvictim];
        if (victim != NULL) {
                loc = CACHE_LOC(xprt, victim->cache_xid);
                for (vicp = &uc->uc_entries[loc];
                  *vicp != NULL && *vicp != victim;
                  vicp = &(*vicp)->cache_next)
                                ;
                if (*vicp == NULL) {
                        CACHE_PERROR("cache_set: victim not found");
                        return;
                }
                *vicp = victim->cache_next;     /* remote from cache */
                newbuf = victim->cache_reply;
        } else {
                victim = ALLOC(struct cache_node, 1);
                if (victim == NULL) {
                        CACHE_PERROR("cache_set: victim alloc failed");
                        return;
                }
                newbuf = mem_alloc(su->su_iosz);
                if (newbuf == NULL) {
                        CACHE_PERROR("cache_set: could not allocate new rpc_buffer");
                        return;
                }
        }

        /*
         * Store it away
         */
        victim->cache_replylen = replylen;
        victim->cache_reply = rpc_buffer(xprt);
        rpc_buffer(xprt) = newbuf;
        xdrmem_create(&(su->su_xdrs), rpc_buffer(xprt), su->su_iosz, XDR_ENCODE);
        victim->cache_xid = su->su_xid;
        victim->cache_proc = uc->uc_proc;
        victim->cache_vers = uc->uc_vers;
        victim->cache_prog = uc->uc_prog;
        victim->cache_addr = uc->uc_addr;
        loc = CACHE_LOC(xprt, victim->cache_xid);
        victim->cache_next = uc->uc_entries[loc];
        uc->uc_entries[loc] = victim;
        uc->uc_fifo[uc->uc_nextvictim++] = victim;
        uc->uc_nextvictim %= uc->uc_size;
}

/*
 * Try to get an entry from the cache
 * return 1 if found, 0 if not found
 */
static int
cache_get(
        SVCXPRT *xprt,
        struct rpc_msg *msg,
        char **replyp,
        u_long *replylenp)
{
        u_int loc;
        register cache_ptr ent;
        register struct svcudp_data *su = su_data(xprt);
        register struct udp_cache *uc = (struct udp_cache *) su->su_cache;

#       define EQADDR(a1, a2)   (memcmp(&a1, &a2, sizeof(a1)) == 0)

        loc = CACHE_LOC(xprt, su->su_xid);
        for (ent = uc->uc_entries[loc]; ent != NULL; ent = ent->cache_next) {
                if (ent->cache_xid == su->su_xid &&
                  ent->cache_proc == uc->uc_proc &&
                  ent->cache_vers == uc->uc_vers &&
                  ent->cache_prog == uc->uc_prog &&
                  EQADDR(ent->cache_addr, uc->uc_addr)) {
                        *replyp = ent->cache_reply;
                        *replylenp = ent->cache_replylen;
                        return(1);
                }
        }
        /*
         * Failed to find entry
         * Remember a few things so we can do a set later
         */
        uc->uc_proc = msg->rm_call.cb_proc;
        uc->uc_vers = msg->rm_call.cb_vers;
        uc->uc_prog = msg->rm_call.cb_prog;
        uc->uc_addr = xprt->xp_raddr;
        return(0);
}