/* @(#)svc_udp.c        2.2 88/07/29 4.0 RPCSRC */
/*
 * Copyright (c) 2010, Oracle America, Inc.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 *     * Neither the name of the "Oracle America, Inc." nor the names of
 *       its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#if !defined(lint) && defined(SCCSIDS)
static char sccsid[] = "@(#)svc_udp.c 1.24 87/08/11 Copyr 1984 Sun Micro";
#endif

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

#include "k5-platform.h"
#include <unistd.h>
#include <gssrpc/rpc.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
#include <port-sockets.h>
#include <socket-utils.h>


#ifndef GETSOCKNAME_ARG3_TYPE
#define GETSOCKNAME_ARG3_TYPE int
#endif

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

static bool_t           svcudp_recv(SVCXPRT *, struct rpc_msg *);
static bool_t           svcudp_reply(SVCXPRT *, struct rpc_msg *);
static enum xprt_stat   svcudp_stat(SVCXPRT *);
static bool_t           svcudp_getargs(SVCXPRT *, xdrproc_t, void *);
static bool_t           svcudp_freeargs(SVCXPRT *, xdrproc_t, void *);
static void             svcudp_destroy(SVCXPRT *);

static void cache_set(SVCXPRT *, uint32_t);
static int cache_get(SVCXPRT *, struct rpc_msg *, char **, uint32_t *);

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 */
        uint32_t        su_xid;         /* transaction id */
        XDR     su_xdrs;        /* XDR handle */
        char    su_verfbody[MAX_AUTH_BYTES];    /* verifier body */
        void *  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_sock 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;
        SVCXPRT *xprt;
        struct svcudp_data *su;
        struct sockaddr_storage ss;
        struct sockaddr *sa = (struct sockaddr *)&ss;
        socklen_t len;

        if (sock == RPC_ANYSOCK) {
                if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
                        perror("svcudp_create: socket creation problem");
                        return ((SVCXPRT *)NULL);
                }
                set_cloexec_fd(sock);
                madesock = TRUE;
                memset(&ss, 0, sizeof(ss));
                sa->sa_family = AF_INET;
        } else {
                len = sizeof(struct sockaddr_storage);
                if (getsockname(sock, sa, &len) < 0) {
                        perror("svcudp_create - cannot getsockname");
                        return ((SVCXPRT *)NULL);
                }
        }

        if (bindresvport_sa(sock, sa)) {
                sa_setport(sa, 0);
                (void)bind(sock, sa, sa_socklen(sa));
        }
        len = sizeof(struct sockaddr_storage);
        if (getsockname(sock, sa, &len) != 0) {
                perror("svcudp_create - cannot getsockname");
                if (madesock)
                        (void)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_auth = NULL;
        xprt->xp_verf.oa_base = su->su_verfbody;
        xprt->xp_ops = &svcudp_op;
        xprt->xp_port = sa_getport(sa);
        xprt->xp_sock = 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)
{
        struct msghdr dummy;
        struct iovec dummy_iov[1];
        struct svcudp_data *su = su_data(xprt);
        XDR *xdrs = &su->su_xdrs;
        int rlen;
        char *reply;
        uint32_t replylen;
        socklen_t addrlen;

    again:
        memset(&dummy, 0, sizeof(dummy));
        dummy_iov[0].iov_base = rpc_buffer(xprt);
        dummy_iov[0].iov_len = (int) su->su_iosz;
        dummy.msg_iov = dummy_iov;
        dummy.msg_iovlen = 1;
        dummy.msg_namelen = xprt->xp_laddrlen = sizeof(struct sockaddr_in);
        dummy.msg_name = (char *) &xprt->xp_laddr;
        rlen = recvmsg(xprt->xp_sock, &dummy, MSG_PEEK);
        if (rlen == -1) {
             if (errno == EINTR)
                  goto again;
             else
                  return (FALSE);
        }

        addrlen = sizeof(struct sockaddr_in);
        rlen = recvfrom(xprt->xp_sock, rpc_buffer(xprt), (int) su->su_iosz,
            0, (struct sockaddr *)&(xprt->xp_raddr), &addrlen);
        if (rlen == -1 && errno == EINTR)
                goto again;
        if (rlen < (int) (4*sizeof(uint32_t)))
                return (FALSE);
        xprt->xp_addrlen = addrlen;
        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_sock, 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)
{
     struct svcudp_data *su = su_data(xprt);
     XDR *xdrs = &su->su_xdrs;
     u_int slen;
     bool_t stat = FALSE;
     ssize_t r;

     xdrproc_t xdr_results = NULL;
     caddr_t xdr_location = 0;
     bool_t has_args;

     if (msg->rm_reply.rp_stat == MSG_ACCEPTED &&
         msg->rm_reply.rp_acpt.ar_stat == SUCCESS) {
          has_args = TRUE;
          xdr_results = msg->acpted_rply.ar_results.proc;
          xdr_location = msg->acpted_rply.ar_results.where;

          msg->acpted_rply.ar_results.proc = xdr_void;
          msg->acpted_rply.ar_results.where = NULL;
     } else
          has_args = FALSE;

     xdrs->x_op = XDR_ENCODE;
     XDR_SETPOS(xdrs, 0);
     msg->rm_xid = su->su_xid;
     if (xdr_replymsg(xdrs, msg) &&
         (!has_args ||
          (SVCAUTH_WRAP(xprt->xp_auth, xdrs, xdr_results, xdr_location)))) {
          slen = XDR_GETPOS(xdrs);
          r = sendto(xprt->xp_sock, rpc_buffer(xprt), slen, 0,
                     (struct sockaddr *)&(xprt->xp_raddr), xprt->xp_addrlen);
          if (r >= 0 && (u_int)r == slen) {
               stat = TRUE;
               if (su->su_cache) {
                    cache_set(xprt, (uint32_t) slen);
               }
          }
     }
     return (stat);
}

static bool_t
svcudp_getargs(
        SVCXPRT *xprt,
        xdrproc_t xdr_args,
        void * args_ptr)
{
        if (! SVCAUTH_UNWRAP(xprt->xp_auth, &(su_data(xprt)->su_xdrs),
                             xdr_args, args_ptr)) {
                (void)svcudp_freeargs(xprt, xdr_args, args_ptr);
                return FALSE;
        }
        return TRUE;
}

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

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

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

        xprt_unregister(xprt);
        if (xprt->xp_sock != INVALID_SOCKET)
                (void)closesocket(xprt->xp_sock);
        xprt->xp_sock = INVALID_SOCKET;
        if (xprt->xp_auth != NULL) {
                SVCAUTH_DESTROY(xprt->xp_auth);
                xprt->xp_auth = NULL;
        }
        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(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
         */
        uint32_t cache_xid;
        rpcproc_t cache_proc;
        rpcvers_t cache_vers;
        rpcprog_t cache_prog;
        struct sockaddr_in cache_addr;
        /*
         * The cached reply and length
         */
        char * cache_reply;
        uint32_t cache_replylen;
        /*
         * Next node on the list, if there is a collision
         */
        cache_ptr cache_next;
};



/*
 * The entire cache
 */
struct udp_cache {
        uint32_t 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 */
        uint32_t uc_nextvictim; /* points to next victim in fifo list */
        rpcprog_t uc_prog;              /* saved program number */
        rpcvers_t uc_vers;              /* saved version number */
        rpcproc_t 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,
        uint32_t 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,
        uint32_t replylen)
{
        cache_ptr victim;
        cache_ptr *vicp;
        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");
                        free(victim);
                        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,
        uint32_t *replylenp)
{
        u_int loc;
        cache_ptr ent;
        struct svcudp_data *su = su_data(xprt);
        struct udp_cache *uc = su->su_cache;

#       define EQADDR(a1, a2) (memcmp((char*)&a1, (char*)&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);
}