nscd/nscd_getserv_r.c

   1 /* Copyright (C) 2007 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2007.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <not-cancel.h>
  23 #include <stdio-common/_itoa.h>
  24
  25 #include "nscd-client.h"
  26 #include "nscd_proto.h"
  27
  28
  29 int __nss_not_use_nscd_services;
  30
  31
  32 static int nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
  33                            request_type type, struct servent *resultbuf,
  34                            char *buf, size_t buflen, struct servent **result);
  35
  36
  37 int
  38 __nscd_getservbyname_r (const char *name, const char *proto,
  39                         struct servent *result_buf, char *buf, size_t buflen,
  40                         struct servent **result)
  41 {
  42   return nscd_getserv_r (name, strlen (name), proto, GETSERVBYNAME, result_buf,
  43                          buf, buflen, result);
  44 }
  45
  46
  47 int
  48 __nscd_getservbyport_r (int port, const char *proto,
  49                         struct servent *result_buf, char *buf, size_t buflen,
  50                         struct servent **result)
  51 {
  52   char portstr[3 * sizeof (int) + 2];
  53   portstr[sizeof (portstr) - 1] = '\0';
  54   char *cp = _itoa_word (port, portstr + sizeof (portstr) - 1, 10, 0);
  55
  56   return nscd_getserv_r (cp, portstr + sizeof (portstr) - cp, proto,
  57                          GETSERVBYPORT, result_buf, buf, buflen, result);
  58 }
  59
  60
  61 libc_locked_map_ptr (, __serv_map_handle) attribute_hidden;
  62 /* Note that we only free the structure if necessary.  The memory
  63    mapping is not removed since it is not visible to the malloc
  64    handling.  */
  65 libc_freeres_fn (serv_map_free)
  66 {
  67   if (__serv_map_handle.mapped != NO_MAPPING)
  68     {
  69       void *p = __serv_map_handle.mapped;
  70       __serv_map_handle.mapped = NO_MAPPING;
  71       free (p);
  72     }
  73 }
  74
  75
  76 static int
  77 nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
  78                 request_type type, struct servent *resultbuf,
  79                 char *buf, size_t buflen, struct servent **result)
  80 {
  81   int gc_cycle;
  82   int nretries = 0;
  83
  84   /* If the mapping is available, try to search there instead of
  85      communicating with the nscd.  */
  86   struct mapped_database *mapped;
  87   mapped = __nscd_get_map_ref (GETFDSERV, "services", &__serv_map_handle,
  88                                &gc_cycle);
  89   size_t protolen = proto == NULL ? 0 : strlen (proto);
  90   size_t keylen = critlen + 1 + protolen + 1;
  91   char *key = alloca (keylen);
  92   memcpy (__mempcpy (__mempcpy (key, crit, critlen),
  93                      "/", 1), proto ?: "", protolen + 1);
  94
  95  retry:;
  96   const char *s_name = NULL;
  97   const char *s_proto = NULL;
  98   const uint32_t *aliases_len = NULL;
  99   const char *aliases_list = NULL;
 100   int retval = -1;
 101   const char *recend = (const char *) ~UINTMAX_C (0);
 102   int sock = -1;
 103   serv_response_header serv_resp;
 104
 105   if (mapped != NO_MAPPING)
 106     {
 107       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped);
 108
 109       if (found != NULL)
 110         {
 111           s_name = (char *) (&found->data[0].servdata + 1);
 112           serv_resp = found->data[0].servdata;
 113           s_proto = s_name + serv_resp.s_name_len;
 114           aliases_len = (uint32_t *) (s_proto + serv_resp.s_proto_len);
 115           aliases_list = ((char *) aliases_len
 116                           + serv_resp.s_aliases_cnt * sizeof (uint32_t));
 117           recend = (const char *) found->data + found->recsize;
 118           /* Now check if we can trust serv_resp fields.  If GC is
 119              in progress, it can contain anything.  */
 120           if (mapped->head->gc_cycle != gc_cycle)
 121             {
 122               retval = -2;
 123               goto out;
 124             }
 125           if (__builtin_expect ((const char *) aliases_len
 126                                 + serv_resp.s_aliases_cnt * sizeof (uint32_t)
 127                                 > recend, 0))
 128             goto out;
 129
 130 #ifndef _STRING_ARCH_unaligned
 131           /* The aliases_len array in the mapped database might very
 132              well be unaligned.  We will access it word-wise so on
 133              platforms which do not tolerate unaligned accesses we
 134              need to make an aligned copy.  */
 135           if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 136               != 0)
 137             {
 138               uint32_t *tmp = alloca (serv_resp.s_aliases_cnt
 139                                       * sizeof (uint32_t));
 140               aliases_len = memcpy (tmp, aliases_len,
 141                                     serv_resp.s_aliases_cnt
 142                                     * sizeof (uint32_t));
 143             }
 144 #endif
 145         }
 146     }
 147
 148   if (s_name == NULL)
 149     {
 150       sock = __nscd_open_socket (key, keylen, type, &serv_resp,
 151                                  sizeof (serv_resp));
 152       if (sock == -1)
 153         {
 154           __nss_not_use_nscd_services = 1;
 155           goto out;
 156         }
 157     }
 158
 159   /* No value found so far.  */
 160   *result = NULL;
 161
 162   if (__builtin_expect (serv_resp.found == -1, 0))
 163     {
 164       /* The daemon does not cache this database.  */
 165       __nss_not_use_nscd_services = 1;
 166       goto out_close;
 167     }
 168
 169   if (serv_resp.found == 1)
 170     {
 171       char *cp = buf;
 172       uintptr_t align1;
 173       uintptr_t align2;
 174       size_t total_len;
 175       ssize_t cnt;
 176       int n;
 177
 178       /* A first check whether the buffer is sufficiently large is possible.  */
 179       /* Now allocate the buffer the array for the group members.  We must
 180          align the pointer and the base of the h_addr_list pointers.  */
 181       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 182                 & (__alignof__ (char *) - 1));
 183       align2 = ((__alignof__ (char *) - ((cp + align1 + serv_resp.s_name_len
 184                                           + serv_resp.s_proto_len)
 185                                          - ((char *) 0)))
 186                 & (__alignof__ (char *) - 1));
 187       if (buflen < (align1 + serv_resp.s_name_len + serv_resp.s_proto_len
 188                     + align2
 189                     + (serv_resp.s_aliases_cnt + 1) * sizeof (char *)))
 190         {
 191         no_room:
 192           __set_errno (ERANGE);
 193           retval = ERANGE;
 194           goto out_close;
 195         }
 196       cp += align1;
 197
 198       /* Prepare the result as far as we can.  */
 199       resultbuf->s_aliases = (char **) cp;
 200       cp += (serv_resp.s_aliases_cnt + 1) * sizeof (char *);
 201
 202       resultbuf->s_name = cp;
 203       cp += serv_resp.s_name_len;
 204       resultbuf->s_proto = cp;
 205       cp += serv_resp.s_proto_len + align2;
 206       resultbuf->s_port = serv_resp.s_port;
 207
 208       if (s_name == NULL)
 209         {
 210           struct iovec vec[2];
 211
 212           vec[0].iov_base = resultbuf->s_name;
 213           vec[0].iov_len = serv_resp.s_name_len + serv_resp.s_proto_len;
 214           total_len = vec[0].iov_len;
 215           n = 1;
 216
 217           if (serv_resp.s_aliases_cnt > 0)
 218             {
 219               aliases_len = alloca (serv_resp.s_aliases_cnt
 220                                     * sizeof (uint32_t));
 221               vec[n].iov_base = (void *) aliases_len;
 222               vec[n].iov_len = serv_resp.s_aliases_cnt * sizeof (uint32_t);
 223
 224               total_len += serv_resp.s_aliases_cnt * sizeof (uint32_t);
 225               ++n;
 226             }
 227
 228           if ((size_t) __readvall (sock, vec, n) != total_len)
 229             goto out_close;
 230         }
 231       else
 232         memcpy (resultbuf->s_name, s_name,
 233                 serv_resp.s_name_len + serv_resp.s_proto_len);
 234
 235       /*  Now we also can read the aliases.  */
 236       total_len = 0;
 237       for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)
 238         {
 239           resultbuf->s_aliases[cnt] = cp;
 240           cp += aliases_len[cnt];
 241           total_len += aliases_len[cnt];
 242         }
 243       resultbuf->s_aliases[cnt] = NULL;
 244
 245       if (__builtin_expect ((const char *) aliases_list + total_len > recend,
 246                             0))
 247         {
 248           /* aliases_len array might contain garbage during nscd GC cycle,
 249              retry rather than fail in that case.  */
 250           if (aliases_list != NULL && mapped->head->gc_cycle != gc_cycle)
 251             retval = -2;
 252           goto out_close;
 253         }
 254
 255       /* See whether this would exceed the buffer capacity.  */
 256       if (__builtin_expect (cp > buf + buflen, 0))
 257         {
 258           /* aliases_len array might contain garbage during nscd GC cycle,
 259              retry rather than fail in that case.  */
 260           if (aliases_list != NULL && mapped->head->gc_cycle != gc_cycle)
 261             {
 262               retval = -2;
 263               goto out_close;
 264             }
 265           goto no_room;
 266         }
 267
 268       /* And finally read the aliases.  */
 269       if (aliases_list == NULL)
 270         {
 271           if (total_len == 0
 272               || ((size_t) __readall (sock, resultbuf->s_aliases[0], total_len)
 273                   == total_len))
 274             {
 275               retval = 0;
 276               *result = resultbuf;
 277             }
 278         }
 279       else
 280         {
 281           memcpy (resultbuf->s_aliases[0], aliases_list, total_len);
 282
 283           /* Try to detect corrupt databases.  */
 284           if (resultbuf->s_name[serv_resp.s_name_len - 1] != '\0'
 285               || resultbuf->s_proto[serv_resp.s_proto_len - 1] != '\0'
 286               || ({for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)
 287                      if (resultbuf->s_aliases[cnt][aliases_len[cnt] - 1]
 288                          != '\0')
 289                        break;
 290                    cnt < serv_resp.s_aliases_cnt; }))
 291             {
 292               /* We cannot use the database.  */
 293               if (mapped->head->gc_cycle != gc_cycle)
 294                 retval = -2;
 295               goto out_close;
 296             }
 297
 298           retval = 0;
 299           *result = resultbuf;
 300         }
 301     }
 302   else
 303     {
 304       /* Set errno to 0 to indicate no error, just no found record.  */
 305       __set_errno (0);
 306       /* Even though we have not found anything, the result is zero.  */
 307       retval = 0;
 308     }
 309
 310  out_close:
 311   if (sock != -1)
 312     close_not_cancel_no_status (sock);
 313  out:
 314   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 315     {
 316       /* When we come here this means there has been a GC cycle while we
 317          were looking for the data.  This means the data might have been
 318          inconsistent.  Retry if possible.  */
 319       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 320         {
 321           /* nscd is just running gc now.  Disable using the mapping.  */
 322           if (atomic_decrement_val (&mapped->counter) == 0)
 323             __nscd_unmap (mapped);
 324           mapped = NO_MAPPING;
 325         }
 326
 327       if (retval != -1)
 328         goto retry;
 329     }
 330
 331   return retval;
 332 }