sunrpc/svc_udp.c

   1 /*
   2  * svc_udp.c,
   3  * Server side for UDP/IP based RPC.  (Does some caching in the hopes of
   4  * achieving execute-at-most-once semantics.)
   5  *
   6  * Copyright (C) 2012-2015 Free Software Foundation, Inc.
   7  * This file is part of the GNU C Library.
   8  *
   9  * The GNU C Library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * The GNU C Library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with the GNU C Library; if not, see
  21  * <http://www.gnu.org/licenses/>.
  22  *
  23  * Copyright (c) 2010, Oracle America, Inc.
  24  *
  25  * Redistribution and use in source and binary forms, with or without
  26  * modification, are permitted provided that the following conditions are
  27  * met:
  28  *
  29  *     * Redistributions of source code must retain the above copyright
  30  *       notice, this list of conditions and the following disclaimer.
  31  *     * Redistributions in binary form must reproduce the above
  32  *       copyright notice, this list of conditions and the following
  33  *       disclaimer in the documentation and/or other materials
  34  *       provided with the distribution.
  35  *     * Neither the name of the "Oracle America, Inc." nor the names of its
  36  *       contributors may be used to endorse or promote products derived
  37  *       from this software without specific prior written permission.
  38  *
  39  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  40  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  41  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  42  *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  43  *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  44  *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  46  *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  47  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  48  *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  49  *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  50  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  51  */
  52
  53 #include <stdio.h>
  54 #include <unistd.h>
  55 #include <string.h>
  56 #include <rpc/rpc.h>
  57 #include <sys/socket.h>
  58 #include <errno.h>
  59 #include <libintl.h>
  60
  61 #ifdef IP_PKTINFO
  62 #include <sys/uio.h>
  63 #endif
  64
  65 #include <wchar.h>
  66 #include <libio/iolibio.h>
  67
  68 #define rpc_buffer(xprt) ((xprt)->xp_p1)
  69 #ifndef MAX
  70 #define MAX(a, b)     ((a > b) ? a : b)
  71 #endif
  72
  73 static bool_t svcudp_recv (SVCXPRT *, struct rpc_msg *);
  74 static bool_t svcudp_reply (SVCXPRT *, struct rpc_msg *);
  75 static enum xprt_stat svcudp_stat (SVCXPRT *);
  76 static bool_t svcudp_getargs (SVCXPRT *, xdrproc_t, caddr_t);
  77 static bool_t svcudp_freeargs (SVCXPRT *, xdrproc_t, caddr_t);
  78 static void svcudp_destroy (SVCXPRT *);
  79
  80 static const struct xp_ops svcudp_op =
  81 {
  82   svcudp_recv,
  83   svcudp_stat,
  84   svcudp_getargs,
  85   svcudp_reply,
  86   svcudp_freeargs,
  87   svcudp_destroy
  88 };
  89
  90 static int cache_get (SVCXPRT *, struct rpc_msg *, char **replyp,
  91                       u_long *replylenp);
  92 static void cache_set (SVCXPRT *xprt, u_long replylen);
  93
  94 /*
  95  * kept in xprt->xp_p2
  96  */
  97 struct svcudp_data
  98   {
  99     u_int su_iosz;              /* byte size of send.recv buffer */
 100     u_long su_xid;              /* transaction id */
 101     XDR su_xdrs;                /* XDR handle */
 102     char su_verfbody[MAX_AUTH_BYTES];   /* verifier body */
 103     char *su_cache;             /* cached data, NULL if no cache */
 104   };
 105 #define su_data(xprt)   ((struct svcudp_data *)(xprt->xp_p2))
 106
 107 /*
 108  * Usage:
 109  *      xprt = svcudp_create(sock);
 110  *
 111  * If sock<0 then a socket is created, else sock is used.
 112  * If the socket, sock is not bound to a port then svcudp_create
 113  * binds it to an arbitrary port.  In any (successful) case,
 114  * xprt->xp_sock is the registered socket number and xprt->xp_port is the
 115  * associated port number.
 116  * Once *xprt is initialized, it is registered as a transporter;
 117  * see (svc.h, xprt_register).
 118  * The routines returns NULL if a problem occurred.
 119  */
 120 SVCXPRT *
 121 svcudp_bufcreate (sock, sendsz, recvsz)
 122      int sock;
 123      u_int sendsz, recvsz;
 124 {
 125   bool_t madesock = FALSE;
 126   SVCXPRT *xprt;
 127   struct svcudp_data *su;
 128   struct sockaddr_in addr;
 129   socklen_t len = sizeof (struct sockaddr_in);
 130   int pad;
 131   void *buf;
 132
 133   if (sock == RPC_ANYSOCK)
 134     {
 135       if ((sock = __socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
 136         {
 137           perror (_("svcudp_create: socket creation problem"));
 138           return (SVCXPRT *) NULL;
 139         }
 140       madesock = TRUE;
 141     }
 142   __bzero ((char *) &addr, sizeof (addr));
 143   addr.sin_family = AF_INET;
 144   if (bindresvport (sock, &addr))
 145     {
 146       addr.sin_port = 0;
 147       (void) __bind (sock, (struct sockaddr *) &addr, len);
 148     }
 149   if (__getsockname (sock, (struct sockaddr *) &addr, &len) != 0)
 150     {
 151       perror (_("svcudp_create - cannot getsockname"));
 152       if (madesock)
 153         (void) __close (sock);
 154       return (SVCXPRT *) NULL;
 155     }
 156   xprt = (SVCXPRT *) mem_alloc (sizeof (SVCXPRT));
 157   su = (struct svcudp_data *) mem_alloc (sizeof (*su));
 158   buf = mem_alloc (((MAX (sendsz, recvsz) + 3) / 4) * 4);
 159   if (xprt == NULL || su == NULL || buf == NULL)
 160     {
 161       (void) __fxprintf (NULL, "%s: %s",
 162                          "svcudp_create",  _("out of memory\n"));
 163       mem_free (xprt, sizeof (SVCXPRT));
 164       mem_free (su, sizeof (*su));
 165       mem_free (buf, ((MAX (sendsz, recvsz) + 3) / 4) * 4);
 166       return NULL;
 167     }
 168   su->su_iosz = ((MAX (sendsz, recvsz) + 3) / 4) * 4;
 169   rpc_buffer (xprt) = buf;
 170   xdrmem_create (&(su->su_xdrs), rpc_buffer (xprt), su->su_iosz, XDR_DECODE);
 171   su->su_cache = NULL;
 172   xprt->xp_p2 = (caddr_t) su;
 173   xprt->xp_verf.oa_base = su->su_verfbody;
 174   xprt->xp_ops = &svcudp_op;
 175   xprt->xp_port = ntohs (addr.sin_port);
 176   xprt->xp_sock = sock;
 177
 178 #ifdef IP_PKTINFO
 179   if ((sizeof (struct iovec) + sizeof (struct msghdr)
 180        + sizeof(struct cmsghdr) + sizeof (struct in_pktinfo))
 181       > sizeof (xprt->xp_pad))
 182     {
 183       (void) __fxprintf (NULL,"%s", _("\
 184 svcudp_create: xp_pad is too small for IP_PKTINFO\n"));
 185       return NULL;
 186     }
 187   pad = 1;
 188   if (__setsockopt (sock, SOL_IP, IP_PKTINFO, (void *) &pad,
 189                     sizeof (pad)) == 0)
 190     /* Set the padding to all 1s. */
 191     pad = 0xff;
 192   else
 193 #endif
 194     /* Clear the padding. */
 195     pad = 0;
 196   memset (&xprt->xp_pad [0], pad, sizeof (xprt->xp_pad));
 197
 198   xprt_register (xprt);
 199   return xprt;
 200 }
 201 #ifdef EXPORT_RPC_SYMBOLS
 202 libc_hidden_def (svcudp_bufcreate)
 203 #else
 204 libc_hidden_nolink_sunrpc (svcudp_bufcreate, GLIBC_2_0)
 205 #endif
 206
 207 SVCXPRT *
 208 svcudp_create (sock)
 209      int sock;
 210 {
 211   return svcudp_bufcreate (sock, UDPMSGSIZE, UDPMSGSIZE);
 212 }
 213 #ifdef EXPORT_RPC_SYMBOLS
 214 libc_hidden_def (svcudp_create)
 215 #else
 216 libc_hidden_nolink_sunrpc (svcudp_create, GLIBC_2_0)
 217 #endif
 218
 219 static enum xprt_stat
 220 svcudp_stat (xprt)
 221      SVCXPRT *xprt;
 222 {
 223
 224   return XPRT_IDLE;
 225 }
 226
 227 static bool_t
 228 svcudp_recv (xprt, msg)
 229      SVCXPRT *xprt;
 230      struct rpc_msg *msg;
 231 {
 232   struct svcudp_data *su = su_data (xprt);
 233   XDR *xdrs = &(su->su_xdrs);
 234   int rlen;
 235   char *reply;
 236   u_long replylen;
 237   socklen_t len;
 238
 239   /* It is very tricky when you have IP aliases. We want to make sure
 240      that we are sending the packet from the IP address where the
 241      incoming packet is addressed to. H.J. */
 242 #ifdef IP_PKTINFO
 243   struct iovec *iovp;
 244   struct msghdr *mesgp;
 245 #endif
 246
 247 again:
 248   /* FIXME -- should xp_addrlen be a size_t?  */
 249   len = (socklen_t) sizeof(struct sockaddr_in);
 250 #ifdef IP_PKTINFO
 251   iovp = (struct iovec *) &xprt->xp_pad [0];
 252   mesgp = (struct msghdr *) &xprt->xp_pad [sizeof (struct iovec)];
 253   if (mesgp->msg_iovlen)
 254     {
 255       iovp->iov_base = rpc_buffer (xprt);
 256       iovp->iov_len = su->su_iosz;
 257       mesgp->msg_iov = iovp;
 258       mesgp->msg_iovlen = 1;
 259       mesgp->msg_name = &(xprt->xp_raddr);
 260       mesgp->msg_namelen = len;
 261       mesgp->msg_control = &xprt->xp_pad [sizeof (struct iovec)
 262                                           + sizeof (struct msghdr)];
 263       mesgp->msg_controllen = sizeof(xprt->xp_pad)
 264                               - sizeof (struct iovec) - sizeof (struct msghdr);
 265       rlen = __recvmsg (xprt->xp_sock, mesgp, 0);
 266       if (rlen >= 0)
 267         {
 268           struct cmsghdr *cmsg;
 269           len = mesgp->msg_namelen;
 270           cmsg = CMSG_FIRSTHDR (mesgp);
 271           if (cmsg == NULL
 272               || CMSG_NXTHDR (mesgp, cmsg) != NULL
 273               || cmsg->cmsg_level != SOL_IP
 274               || cmsg->cmsg_type != IP_PKTINFO
 275               || cmsg->cmsg_len < (sizeof (struct cmsghdr)
 276                                    + sizeof (struct in_pktinfo)))
 277             {
 278               /* Not a simple IP_PKTINFO, ignore it.  */
 279               mesgp->msg_control = NULL;
 280               mesgp->msg_controllen = 0;
 281             }
 282           else
 283             {
 284               /* It was a simple IP_PKTIFO as we expected, discard the
 285                  interface field.  */
 286               struct in_pktinfo *pkti = (struct in_pktinfo *) CMSG_DATA (cmsg);
 287               pkti->ipi_ifindex = 0;
 288             }
 289         }
 290     }
 291   else
 292 #endif
 293     rlen = __recvfrom (xprt->xp_sock, rpc_buffer (xprt),
 294                        (int) su->su_iosz, 0,
 295                        (struct sockaddr *) &(xprt->xp_raddr), &len);
 296   xprt->xp_addrlen = len;
 297   if (rlen == -1)
 298     {
 299       if (errno == EINTR)
 300         goto again;
 301       __svc_accept_failed ();
 302     }
 303   if (rlen < 16)                /* < 4 32-bit ints? */
 304     return FALSE;
 305   xdrs->x_op = XDR_DECODE;
 306   XDR_SETPOS (xdrs, 0);
 307   if (!xdr_callmsg (xdrs, msg))
 308     return FALSE;
 309   su->su_xid = msg->rm_xid;
 310   if (su->su_cache != NULL)
 311     {
 312       if (cache_get (xprt, msg, &reply, &replylen))
 313         {
 314 #ifdef IP_PKTINFO
 315           if (mesgp->msg_iovlen)
 316             {
 317               iovp->iov_base = reply;
 318               iovp->iov_len = replylen;
 319               (void) __sendmsg (xprt->xp_sock, mesgp, 0);
 320             }
 321           else
 322 #endif
 323             (void) __sendto (xprt->xp_sock, reply, (int) replylen, 0,
 324                              (struct sockaddr *) &xprt->xp_raddr, len);
 325           return TRUE;
 326         }
 327     }
 328   return TRUE;
 329 }
 330
 331 static bool_t
 332 svcudp_reply (xprt, msg)
 333      SVCXPRT *xprt;
 334      struct rpc_msg *msg;
 335 {
 336   struct svcudp_data *su = su_data (xprt);
 337   XDR *xdrs = &(su->su_xdrs);
 338   int slen, sent;
 339   bool_t stat = FALSE;
 340 #ifdef IP_PKTINFO
 341   struct iovec *iovp;
 342   struct msghdr *mesgp;
 343 #endif
 344
 345   xdrs->x_op = XDR_ENCODE;
 346   XDR_SETPOS (xdrs, 0);
 347   msg->rm_xid = su->su_xid;
 348   if (xdr_replymsg (xdrs, msg))
 349     {
 350       slen = (int) XDR_GETPOS (xdrs);
 351 #ifdef IP_PKTINFO
 352       mesgp = (struct msghdr *) &xprt->xp_pad [sizeof (struct iovec)];
 353       if (mesgp->msg_iovlen)
 354         {
 355           iovp = (struct iovec *) &xprt->xp_pad [0];
 356           iovp->iov_base = rpc_buffer (xprt);
 357           iovp->iov_len = slen;
 358           sent = __sendmsg (xprt->xp_sock, mesgp, 0);
 359         }
 360       else
 361 #endif
 362         sent = __sendto (xprt->xp_sock, rpc_buffer (xprt), slen, 0,
 363                          (struct sockaddr *) &(xprt->xp_raddr),
 364                          xprt->xp_addrlen);
 365       if (sent == slen)
 366         {
 367           stat = TRUE;
 368           if (su->su_cache && slen >= 0)
 369             {
 370               cache_set (xprt, (u_long) slen);
 371             }
 372         }
 373     }
 374   return stat;
 375 }
 376
 377 static bool_t
 378 svcudp_getargs (xprt, xdr_args, args_ptr)
 379      SVCXPRT *xprt;
 380      xdrproc_t xdr_args;
 381      caddr_t args_ptr;
 382 {
 383
 384   return (*xdr_args) (&(su_data (xprt)->su_xdrs), args_ptr);
 385 }
 386
 387 static bool_t
 388 svcudp_freeargs (xprt, xdr_args, args_ptr)
 389      SVCXPRT *xprt;
 390      xdrproc_t xdr_args;
 391      caddr_t args_ptr;
 392 {
 393   XDR *xdrs = &(su_data (xprt)->su_xdrs);
 394
 395   xdrs->x_op = XDR_FREE;
 396   return (*xdr_args) (xdrs, args_ptr);
 397 }
 398
 399 static void
 400 svcudp_destroy (xprt)
 401      SVCXPRT *xprt;
 402 {
 403   struct svcudp_data *su = su_data (xprt);
 404
 405   xprt_unregister (xprt);
 406   (void) __close (xprt->xp_sock);
 407   XDR_DESTROY (&(su->su_xdrs));
 408   mem_free (rpc_buffer (xprt), su->su_iosz);
 409   mem_free ((caddr_t) su, sizeof (struct svcudp_data));
 410   mem_free ((caddr_t) xprt, sizeof (SVCXPRT));
 411 }
 412
 413
 414 /***********this could be a separate file*********************/
 415
 416 /*
 417  * Fifo cache for udp server
 418  * Copies pointers to reply buffers into fifo cache
 419  * Buffers are sent again if retransmissions are detected.
 420  */
 421
 422 #define SPARSENESS 4            /* 75% sparse */
 423
 424 #define CACHE_PERROR(msg)       \
 425         (void) __fxprintf(NULL, "%s\n", msg)
 426
 427 #define ALLOC(type, size)       \
 428         (type *) mem_alloc((unsigned) (sizeof(type) * (size)))
 429
 430 #define CALLOC(type, size)      \
 431   (type *) calloc (sizeof (type), size)
 432
 433 /*
 434  * An entry in the cache
 435  */
 436 typedef struct cache_node *cache_ptr;
 437 struct cache_node
 438   {
 439     /*
 440      * Index into cache is xid, proc, vers, prog and address
 441      */
 442     u_long cache_xid;
 443     u_long cache_proc;
 444     u_long cache_vers;
 445     u_long cache_prog;
 446     struct sockaddr_in cache_addr;
 447     /*
 448      * The cached reply and length
 449      */
 450     char *cache_reply;
 451     u_long cache_replylen;
 452     /*
 453      * Next node on the list, if there is a collision
 454      */
 455     cache_ptr cache_next;
 456   };
 457
 458
 459
 460 /*
 461  * The entire cache
 462  */
 463 struct udp_cache
 464   {
 465     u_long uc_size;             /* size of cache */
 466     cache_ptr *uc_entries;      /* hash table of entries in cache */
 467     cache_ptr *uc_fifo;         /* fifo list of entries in cache */
 468     u_long uc_nextvictim;       /* points to next victim in fifo list */
 469     u_long uc_prog;             /* saved program number */
 470     u_long uc_vers;             /* saved version number */
 471     u_long uc_proc;             /* saved procedure number */
 472     struct sockaddr_in uc_addr; /* saved caller's address */
 473   };
 474
 475
 476 /*
 477  * the hashing function
 478  */
 479 #define CACHE_LOC(transp, xid)  \
 480  (xid % (SPARSENESS*((struct udp_cache *) su_data(transp)->su_cache)->uc_size))
 481
 482
 483 /*
 484  * Enable use of the cache.
 485  * Note: there is no disable.
 486  */
 487 int
 488 svcudp_enablecache (SVCXPRT *transp, u_long size)
 489 {
 490   struct svcudp_data *su = su_data (transp);
 491   struct udp_cache *uc;
 492
 493   if (su->su_cache != NULL)
 494     {
 495       CACHE_PERROR (_("enablecache: cache already enabled"));
 496       return 0;
 497     }
 498   uc = ALLOC (struct udp_cache, 1);
 499   if (uc == NULL)
 500     {
 501       CACHE_PERROR (_("enablecache: could not allocate cache"));
 502       return 0;
 503     }
 504   uc->uc_size = size;
 505   uc->uc_nextvictim = 0;
 506   uc->uc_entries = CALLOC (cache_ptr, size * SPARSENESS);
 507   if (uc->uc_entries == NULL)
 508     {
 509       mem_free (uc, sizeof (struct udp_cache));
 510       CACHE_PERROR (_("enablecache: could not allocate cache data"));
 511       return 0;
 512     }
 513   uc->uc_fifo = CALLOC (cache_ptr, size);
 514   if (uc->uc_fifo == NULL)
 515     {
 516       mem_free (uc->uc_entries, size * SPARSENESS);
 517       mem_free (uc, sizeof (struct udp_cache));
 518       CACHE_PERROR (_("enablecache: could not allocate cache fifo"));
 519       return 0;
 520     }
 521   su->su_cache = (char *) uc;
 522   return 1;
 523 }
 524 libc_hidden_nolink_sunrpc (svcudp_enablecache, GLIBC_2_0)
 525
 526
 527 /*
 528  * Set an entry in the cache
 529  */
 530 static void
 531 cache_set (SVCXPRT *xprt, u_long replylen)
 532 {
 533   cache_ptr victim;
 534   cache_ptr *vicp;
 535   struct svcudp_data *su = su_data (xprt);
 536   struct udp_cache *uc = (struct udp_cache *) su->su_cache;
 537   u_int loc;
 538   char *newbuf;
 539
 540   /*
 541    * Find space for the new entry, either by
 542    * reusing an old entry, or by mallocing a new one
 543    */
 544   victim = uc->uc_fifo[uc->uc_nextvictim];
 545   if (victim != NULL)
 546     {
 547       loc = CACHE_LOC (xprt, victim->cache_xid);
 548       for (vicp = &uc->uc_entries[loc];
 549            *vicp != NULL && *vicp != victim;
 550            vicp = &(*vicp)->cache_next)
 551         ;
 552       if (*vicp == NULL)
 553         {
 554           CACHE_PERROR (_("cache_set: victim not found"));
 555           return;
 556         }
 557       *vicp = victim->cache_next;       /* remote from cache */
 558       newbuf = victim->cache_reply;
 559     }
 560   else
 561     {
 562       victim = ALLOC (struct cache_node, 1);
 563       if (victim == NULL)
 564         {
 565           CACHE_PERROR (_("cache_set: victim alloc failed"));
 566           return;
 567         }
 568       newbuf = mem_alloc (su->su_iosz);
 569       if (newbuf == NULL)
 570         {
 571           mem_free (victim, sizeof (struct cache_node));
 572           CACHE_PERROR (_("cache_set: could not allocate new rpc_buffer"));
 573           return;
 574         }
 575     }
 576
 577   /*
 578    * Store it away
 579    */
 580   victim->cache_replylen = replylen;
 581   victim->cache_reply = rpc_buffer (xprt);
 582   rpc_buffer (xprt) = newbuf;
 583   xdrmem_create (&(su->su_xdrs), rpc_buffer (xprt), su->su_iosz, XDR_ENCODE);
 584   victim->cache_xid = su->su_xid;
 585   victim->cache_proc = uc->uc_proc;
 586   victim->cache_vers = uc->uc_vers;
 587   victim->cache_prog = uc->uc_prog;
 588   victim->cache_addr = uc->uc_addr;
 589   loc = CACHE_LOC (xprt, victim->cache_xid);
 590   victim->cache_next = uc->uc_entries[loc];
 591   uc->uc_entries[loc] = victim;
 592   uc->uc_fifo[uc->uc_nextvictim++] = victim;
 593   uc->uc_nextvictim %= uc->uc_size;
 594 }
 595
 596 /*
 597  * Try to get an entry from the cache
 598  * return 1 if found, 0 if not found
 599  */
 600 static int
 601 cache_get (xprt, msg, replyp, replylenp)
 602      SVCXPRT *xprt;
 603      struct rpc_msg *msg;
 604      char **replyp;
 605      u_long *replylenp;
 606 {
 607   u_int loc;
 608   cache_ptr ent;
 609   struct svcudp_data *su = su_data (xprt);
 610   struct udp_cache *uc = (struct udp_cache *) su->su_cache;
 611
 612 #define EQADDR(a1, a2)  (memcmp((char*)&a1, (char*)&a2, sizeof(a1)) == 0)
 613
 614   loc = CACHE_LOC (xprt, su->su_xid);
 615   for (ent = uc->uc_entries[loc]; ent != NULL; ent = ent->cache_next)
 616     {
 617       if (ent->cache_xid == su->su_xid &&
 618           ent->cache_proc == uc->uc_proc &&
 619           ent->cache_vers == uc->uc_vers &&
 620           ent->cache_prog == uc->uc_prog &&
 621           EQADDR (ent->cache_addr, uc->uc_addr))
 622         {
 623           *replyp = ent->cache_reply;
 624           *replylenp = ent->cache_replylen;
 625           return 1;
 626         }
 627     }
 628   /*
 629    * Failed to find entry
 630    * Remember a few things so we can do a set later
 631    */
 632   uc->uc_proc = msg->rm_call.cb_proc;
 633   uc->uc_vers = msg->rm_call.cb_vers;
 634   uc->uc_prog = msg->rm_call.cb_prog;
 635   memcpy (&uc->uc_addr, &xprt->xp_raddr, sizeof (uc->uc_addr));
 636   return 0;
 637 }