nis/nis_lookup.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 <rpcsvc/nis.h>
  20 #include "nis_xdr.h"
  21 #include "nis_intern.h"
  22 #include <libnsl.h>
  23 #include <shlib-compat.h>
  24
  25
  26 nis_result *
  27 nis_lookup (const_nis_name name, const unsigned int flags)
  28 {
  29   nis_result *res = calloc (1, sizeof (nis_result));
  30   struct ns_request req;
  31   nis_name *names;
  32   nis_error status;
  33   int link_first_try = 0;
  34   int count_links = 0;   /* We will follow only 16 links in the deep */
  35   int done = 0;
  36   int name_nr = 0;
  37   nis_name namebuf[2] = {NULL, NULL};
  38
  39   if (res == NULL)
  40     return NULL;
  41
  42   if ((flags & EXPAND_NAME) && (name[strlen (name) - 1] != '.'))
  43     {
  44       names = nis_getnames (name);
  45       if (names == NULL)
  46         {
  47           NIS_RES_STATUS (res) = NIS_NAMEUNREACHABLE;
  48           return res;
  49         }
  50     }
  51   else
  52     {
  53       names = namebuf;
  54       names[0] = (nis_name)name;
  55     }
  56
  57   req.ns_name = names[0];
  58   while (!done)
  59     {
  60       dir_binding bptr;
  61       directory_obj *dir = NULL;
  62       req.ns_object.ns_object_len = 0;
  63       req.ns_object.ns_object_val = NULL;
  64
  65       status = __prepare_niscall (req.ns_name, &dir, &bptr, flags);
  66       if (__glibc_unlikely (status != NIS_SUCCESS))
  67         {
  68           NIS_RES_STATUS (res) = status;
  69           goto out;
  70         }
  71
  72       do
  73         {
  74           static const struct timeval RPCTIMEOUT = {10, 0};
  75           enum clnt_stat result;
  76
  77         again:
  78           result = clnt_call (bptr.clnt, NIS_LOOKUP,
  79                               (xdrproc_t) _xdr_ns_request,
  80                               (caddr_t) &req, (xdrproc_t) _xdr_nis_result,
  81                               (caddr_t) res, RPCTIMEOUT);
  82
  83           if (result != RPC_SUCCESS)
  84             status = NIS_RPCERROR;
  85           else
  86             {
  87               status = NIS_SUCCESS;
  88
  89               if (NIS_RES_STATUS (res) == NIS_SUCCESS)
  90                 {
  91                     if (__type_of (NIS_RES_OBJECT (res)) == NIS_LINK_OBJ
  92                         && (flags & FOLLOW_LINKS)) /* We are following links */
  93                       {
  94                         /* if we hit the link limit, bail */
  95                         if (count_links > NIS_MAXLINKS)
  96                           {
  97                             NIS_RES_STATUS (res) = NIS_LINKNAMEERROR;
  98                             break;
  99                           }
 100                         ++count_links;
 101                         req.ns_name =
 102                           strdupa (NIS_RES_OBJECT (res)->LI_data.li_name);
 103
 104                         /* The following is a non-obvious optimization.  A
 105                            nis_freeresult call would call xdr_free as the
 106                            following code.  But it also would unnecessarily
 107                            free the result structure.  We avoid this here
 108                            along with the necessary tests.  */
 109                         xdr_free ((xdrproc_t) _xdr_nis_result, (char *) res);
 110                         memset (res, '\0', sizeof (*res));
 111
 112                         link_first_try = 1; /* Try at first the old binding */
 113                         goto again;
 114                       }
 115                 }
 116               else
 117                 if (NIS_RES_STATUS (res) == NIS_SYSTEMERROR
 118                     || NIS_RES_STATUS (res) == NIS_NOSUCHNAME
 119                     || NIS_RES_STATUS (res) == NIS_NOT_ME)
 120                   {
 121                     if (link_first_try)
 122                       {
 123                         __nisbind_destroy (&bptr);
 124                         nis_free_directory (dir);
 125                         /* Otherwise __nisfind_server will not do anything.  */
 126                         dir = NULL;
 127
 128                         if (__nisfind_server (req.ns_name, 1, &dir, &bptr,
 129                                               flags & ~MASTER_ONLY)
 130                             != NIS_SUCCESS)
 131                           goto out;
 132                       }
 133                     else
 134                       if (__nisbind_next (&bptr) != NIS_SUCCESS)
 135                         {
 136                           /* No more servers to search.  Try parent.  */
 137                           const char *ndomain = __nis_domain_of (req.ns_name);
 138                           req.ns_name = strdupa (ndomain);
 139                           if (strcmp (req.ns_name, ".") == 0)
 140                             {
 141                               NIS_RES_STATUS (res) = NIS_NAMEUNREACHABLE;
 142                               goto out;
 143                             }
 144
 145                           __nisbind_destroy (&bptr);
 146                           nis_free_directory (dir);
 147                           dir = NULL;
 148                           status = __prepare_niscall (req.ns_name, &dir,
 149                                                       &bptr, flags);
 150                           if (__glibc_unlikely (status != NIS_SUCCESS))
 151                             {
 152                               NIS_RES_STATUS (res) = status;
 153                               goto out;
 154                             }
 155                           goto again;
 156                         }
 157
 158                     while (__nisbind_connect (&bptr) != NIS_SUCCESS)
 159                       {
 160                         if (__nisbind_next (&bptr) != NIS_SUCCESS)
 161                           {
 162                             nis_free_directory (dir);
 163                             goto out;
 164                           }
 165                       }
 166                     goto again;
 167                   }
 168               break;
 169             }
 170           link_first_try = 0; /* Set it back */
 171         }
 172       while ((flags & HARD_LOOKUP) && status == NIS_RPCERROR);
 173
 174       __nisbind_destroy (&bptr);
 175       nis_free_directory (dir);
 176
 177       if (status != NIS_SUCCESS)
 178         {
 179           NIS_RES_STATUS (res) = status;
 180           goto out;
 181         }
 182
 183       switch (NIS_RES_STATUS (res))
 184         {
 185         case NIS_PARTIAL:
 186         case NIS_SUCCESS:
 187         case NIS_S_SUCCESS:
 188         case NIS_LINKNAMEERROR: /* We follow to max links */
 189         case NIS_UNAVAIL: /* NIS+ is not installed, or all servers are down */
 190           ++done;
 191           break;
 192         default:
 193           /* Try the next domainname if we don't follow a link */
 194           if (count_links)
 195             {
 196               free (req.ns_name);
 197               NIS_RES_STATUS (res) = NIS_LINKNAMEERROR;
 198               ++done;
 199               break;
 200             }
 201           ++name_nr;
 202           if (names[name_nr] == NULL)
 203             {
 204               ++done;
 205               break;
 206             }
 207           req.ns_name = names[name_nr];
 208           break;
 209         }
 210     }
 211
 212  out:
 213   if (names != namebuf)
 214     nis_freenames (names);
 215
 216   return res;
 217 }
 218 libnsl_hidden_nolink_def (nis_lookup, GLIBC_2_1)