nis/nis_findserv.c

   1 /* Copyright (C) 1997-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19 #include <time.h>
  20 #include <unistd.h>
  21 #include <sys/ioctl.h>
  22 #include <sys/socket.h>
  23 #include <rpc/pmap_prot.h>
  24 #include <rpc/pmap_clnt.h>
  25 #include <rpcsvc/nis.h>
  26
  27 #include "nis_intern.h"
  28
  29 /* Private data kept per client handle, from sunrpc/clnt_udp.c */
  30 struct cu_data
  31   {
  32     int cu_sock;
  33     bool_t cu_closeit;
  34     struct sockaddr_in cu_raddr;
  35     int cu_rlen;
  36     struct timeval cu_wait;
  37     struct timeval cu_total;
  38     struct rpc_err cu_error;
  39     XDR cu_outxdrs;
  40     u_int cu_xdrpos;
  41     u_int cu_sendsz;
  42     char *cu_outbuf;
  43     u_int cu_recvsz;
  44     char cu_inbuf[1];
  45   };
  46
  47
  48 /*
  49  * Find the mapped port for program,version.
  50  * Calls the pmap service remotely to do the lookup.
  51  * Returns 0 if no map exists.
  52  */
  53 u_short
  54 __pmap_getnisport (struct sockaddr_in *address, u_long program,
  55                    u_long version, u_int protocol)
  56 {
  57   return __libc_rpc_getport (address, program, version, protocol, 1, 1);
  58 }
  59
  60 /* This is now the public function, which should find the fastest server */
  61
  62 struct findserv_req
  63 {
  64   struct sockaddr_in sin;
  65   uint32_t xid;
  66   u_int server_nr;
  67   u_int server_ep;
  68 };
  69
  70
  71 static long int
  72 __nis_findfastest_with_timeout (dir_binding *bind,
  73                                 const struct timeval *timeout)
  74 {
  75   static const struct timeval TIMEOUT00 = { 0, 0 };
  76   struct findserv_req *pings;
  77   struct sockaddr_in sin, saved_sin;
  78   int found = -1;
  79   uint32_t xid_seed;
  80   int sock, dontblock = 1;
  81   CLIENT *clnt;
  82   u_long i, j, pings_count, pings_max, fastest = -1;
  83   struct cu_data *cu;
  84
  85   pings_max = bind->server_len * 2;     /* Reserve a little bit more memory
  86                                            for multihomed hosts */
  87   pings_count = 0;
  88   pings = malloc (sizeof (struct findserv_req) * pings_max);
  89   xid_seed = (uint32_t) (time (NULL) ^ getpid ());
  90
  91   if (__glibc_unlikely (pings == NULL))
  92     return -1;
  93
  94   memset (&sin, '\0', sizeof (sin));
  95   sin.sin_family = AF_INET;
  96   for (i = 0; i < bind->server_len; i++)
  97     for (j = 0; j < bind->server_val[i].ep.ep_len; ++j)
  98       if (strcmp (bind->server_val[i].ep.ep_val[j].family, "inet") == 0)
  99         if ((bind->server_val[i].ep.ep_val[j].proto == NULL)
 100             || (bind->server_val[i].ep.ep_val[j].proto[0] == '-')
 101             || (bind->server_val[i].ep.ep_val[j].proto[0] == '\0'))
 102           {
 103             sin.sin_addr.s_addr =
 104               inetstr2int (bind->server_val[i].ep.ep_val[j].uaddr);
 105             if (sin.sin_addr.s_addr == 0)
 106               continue;
 107             sin.sin_port = htons (__pmap_getnisport (&sin, NIS_PROG,
 108                                                      NIS_VERSION,
 109                                                      IPPROTO_UDP));
 110             if (sin.sin_port == 0)
 111               continue;
 112
 113             if (pings_count >= pings_max)
 114               {
 115                 struct findserv_req *new_pings;
 116
 117                 pings_max += 10;
 118                 new_pings = realloc (pings, sizeof (struct findserv_req) *
 119                                      pings_max);
 120                 if (__glibc_unlikely (new_pings == NULL))
 121                   {
 122                     free (pings);
 123                     return -1;
 124                   }
 125                 pings = new_pings;
 126               }
 127             memcpy ((char *) &pings[pings_count].sin, (char *) &sin,
 128                     sizeof (sin));
 129             memcpy ((char *)&saved_sin, (char *)&sin, sizeof (sin));
 130             pings[pings_count].xid = xid_seed + pings_count;
 131             pings[pings_count].server_nr = i;
 132             pings[pings_count].server_ep = j;
 133             ++pings_count;
 134           }
 135
 136   /* Make sure at least one server was assigned */
 137   if (pings_count == 0)
 138     {
 139       free (pings);
 140       return -1;
 141     }
 142
 143   /* Create RPC handle */
 144   sock = socket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
 145   clnt = clntudp_create (&saved_sin, NIS_PROG, NIS_VERSION, *timeout, &sock);
 146   if (clnt == NULL)
 147     {
 148       close (sock);
 149       free (pings);
 150       return -1;
 151     }
 152   auth_destroy (clnt->cl_auth);
 153   clnt->cl_auth = authunix_create_default ();
 154   cu = (struct cu_data *) clnt->cl_private;
 155   ioctl (sock, FIONBIO, &dontblock);
 156   /* Send to all servers the NULLPROC */
 157   for (i = 0; i < pings_count; ++i)
 158     {
 159       /* clntudp_call() will increment, subtract one */
 160       *((uint32_t *) (cu->cu_outbuf)) = pings[i].xid - 1;
 161       memcpy ((char *) &cu->cu_raddr, (char *) &pings[i].sin,
 162               sizeof (struct sockaddr_in));
 163       /* Transmit to NULLPROC, return immediately. */
 164       clnt_call (clnt, NULLPROC,
 165                  (xdrproc_t) xdr_void, (caddr_t) 0,
 166                  (xdrproc_t) xdr_void, (caddr_t) 0, TIMEOUT00);
 167     }
 168
 169   while (found == -1) {
 170     /* Receive reply from NULLPROC asynchronously. Note null inproc. */
 171     int rc = clnt_call (clnt, NULLPROC,
 172                         (xdrproc_t) NULL, (caddr_t) 0,
 173                         (xdrproc_t) xdr_void, (caddr_t) 0,
 174                         *timeout);
 175     if (RPC_SUCCESS == rc) {
 176       uint32_t val;
 177       memcpy (&val, cu->cu_inbuf, sizeof (uint32_t));
 178       fastest = val - xid_seed;
 179       if (fastest < pings_count) {
 180         bind->server_used = pings[fastest].server_nr;
 181         bind->current_ep = pings[fastest].server_ep;
 182         found = 1;
 183       }
 184     } else {
 185       /*      clnt_perror(clnt, "__nis_findfastest"); */
 186       break;
 187     }
 188   }
 189
 190
 191   auth_destroy (clnt->cl_auth);
 192   clnt_destroy (clnt);
 193   close (sock);
 194
 195   free (pings);
 196
 197   return found;
 198 }
 199
 200
 201 long int
 202 __nis_findfastest (dir_binding *bind)
 203 {
 204   struct timeval timeout = { __NIS_PING_TIMEOUT_START, 0 };
 205   long int found = -1;
 206   long int retry = __NIS_PING_RETRY + 1;
 207
 208   while (retry--)
 209     {
 210       found = __nis_findfastest_with_timeout (bind, &timeout);
 211       if (found != -1)
 212         break;
 213       timeout.tv_sec += __NIS_PING_TIMEOUT_INCREMENT;
 214     }
 215
 216   return found;
 217 }