nss/nss_files/files-hosts.c

   1 /* Hosts file parser in nss_files module.
   2    Copyright (C) 1996-2001, 2003, 2004, 2006, 2007
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <assert.h>
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24 #include <arpa/nameser.h>
  25 #include <netdb.h>
  26 #include <resolv.h>
  27
  28
  29 /* Get implementation for some internal functions.  */
  30 #include "../resolv/mapv4v6addr.h"
  31 #include "../resolv/res_hconf.h"
  32
  33
  34 #define ENTNAME         hostent
  35 #define DATABASE        "hosts"
  36 #define NEED_H_ERRNO
  37
  38 #define EXTRA_ARGS       , af, flags
  39 #define EXTRA_ARGS_DECL  , int af, int flags
  40
  41 #define ENTDATA hostent_data
  42 struct hostent_data
  43   {
  44     unsigned char host_addr[16]; /* IPv4 or IPv6 address.  */
  45     char *h_addr_ptrs[2];       /* Points to that and null terminator.  */
  46   };
  47
  48 #define TRAILING_LIST_MEMBER            h_aliases
  49 #define TRAILING_LIST_SEPARATOR_P       isspace
  50 #include "files-parse.c"
  51 LINE_PARSER
  52 ("#",
  53  {
  54    char *addr;
  55
  56    STRING_FIELD (addr, isspace, 1);
  57
  58    /* Parse address.  */
  59    if (inet_pton (af, addr, entdata->host_addr) <= 0)
  60      {
  61        if (af == AF_INET6 && (flags & AI_V4MAPPED) != 0
  62            && inet_pton (AF_INET, addr, entdata->host_addr) > 0)
  63          map_v4v6_address ((char *) entdata->host_addr,
  64                            (char *) entdata->host_addr);
  65        else if (af == AF_INET
  66                 && inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
  67          {
  68            if (IN6_IS_ADDR_V4MAPPED (entdata->host_addr))
  69              memcpy (entdata->host_addr, entdata->host_addr + 12, INADDRSZ);
  70            else if (IN6_IS_ADDR_LOOPBACK (entdata->host_addr))
  71              {
  72                in_addr_t localhost = htonl (INADDR_LOOPBACK);
  73                memcpy (entdata->host_addr, &localhost, sizeof (localhost));
  74              }
  75            else
  76              /* Illegal address: ignore line.  */
  77              return 0;
  78          }
  79        else
  80          /* Illegal address: ignore line.  */
  81          return 0;
  82      }
  83
  84    /* We always return entries of the requested form.  */
  85    result->h_addrtype = af;
  86    result->h_length = af == AF_INET ? INADDRSZ : IN6ADDRSZ;
  87
  88    /* Store a pointer to the address in the expected form.  */
  89    entdata->h_addr_ptrs[0] = (char *) entdata->host_addr;
  90    entdata->h_addr_ptrs[1] = NULL;
  91    result->h_addr_list = entdata->h_addr_ptrs;
  92
  93    STRING_FIELD (result->h_name, isspace, 1);
  94  })
  95
  96
  97
  98 #define HOST_DB_LOOKUP(name, keysize, keypattern, break_if_match, proto...) \
  99 enum nss_status                                                               \
 100 _nss_files_get##name##_r (proto,                                              \
 101                           struct STRUCTURE *result, char *buffer,             \
 102                           size_t buflen, int *errnop H_ERRNO_PROTO)           \
 103 {                                                                             \
 104   enum nss_status status;                                                     \
 105                                                                               \
 106   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct hostent_data);    \
 107   buffer += pad;                                                              \
 108   buflen = buflen > pad ? buflen - pad : 0;                                   \
 109                                                                               \
 110   __libc_lock_lock (lock);                                                    \
 111                                                                               \
 112   /* Reset file pointer to beginning or open file.  */                        \
 113   status = internal_setent (keep_stream);                                     \
 114                                                                               \
 115   if (status == NSS_STATUS_SUCCESS)                                           \
 116     {                                                                         \
 117       /* Tell getent function that we have repositioned the file pointer.  */ \
 118       last_use = getby;                                                       \
 119                                                                               \
 120       while ((status = internal_getent (result, buffer, buflen, errnop        \
 121                                         H_ERRNO_ARG EXTRA_ARGS_VALUE))        \
 122              == NSS_STATUS_SUCCESS)                                           \
 123         { break_if_match }                                                    \
 124                                                                               \
 125       if (status == NSS_STATUS_SUCCESS                                        \
 126           && _res_hconf.flags & HCONF_FLAG_MULTI)                             \
 127         {                                                                     \
 128           /* We have to get all host entries from the file.  */               \
 129           const size_t tmp_buflen = MIN (buflen, 4096);                       \
 130           char tmp_buffer[tmp_buflen]                                         \
 131             __attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));\
 132           struct hostent tmp_result_buf;                                      \
 133           int naddrs = 1;                                                     \
 134           int naliases = 0;                                                   \
 135           char *bufferend;                                                    \
 136                                                                               \
 137           while (result->h_aliases[naliases] != NULL)                         \
 138             ++naliases;                                                       \
 139                                                                               \
 140           bufferend = (char *) &result->h_aliases[naliases + 1];              \
 141                                                                               \
 142           while ((status = internal_getent (&tmp_result_buf, tmp_buffer,      \
 143                                             tmp_buflen, errnop H_ERRNO_ARG    \
 144                                             EXTRA_ARGS_VALUE))                \
 145                  == NSS_STATUS_SUCCESS)                                       \
 146             {                                                                 \
 147               int matches = 1;                                                \
 148               struct hostent *old_result = result;                            \
 149               result = &tmp_result_buf;                                       \
 150               /* The following piece is a bit clumsy but we want to use the   \
 151                  `break_if_match' value.  The optimizer should do its         \
 152                  job.  */                                                     \
 153               do                                                              \
 154                 {                                                             \
 155                   break_if_match                                              \
 156                   result = old_result;                                        \
 157                 }                                                             \
 158               while ((matches = 0));                                          \
 159                                                                               \
 160               if (matches)                                                    \
 161                 {                                                             \
 162                   /* We could be very clever and try to recycle a few bytes   \
 163                      in the buffer instead of generating new arrays.  But     \
 164                      we are not doing this here since it's more work than     \
 165                      it's worth.  Simply let the user provide a bit bigger    \
 166                      buffer.  */                                              \
 167                   char **new_h_addr_list;                                     \
 168                   char **new_h_aliases;                                       \
 169                   int newaliases = 0;                                         \
 170                   size_t newstrlen = 0;                                       \
 171                   int cnt;                                                    \
 172                                                                               \
 173                   /* Count the new aliases and the length of the strings.  */ \
 174                   while (tmp_result_buf.h_aliases[newaliases] != NULL)        \
 175                     {                                                         \
 176                       char *cp = tmp_result_buf.h_aliases[newaliases];        \
 177                       ++newaliases;                                           \
 178                       newstrlen += strlen (cp) + 1;                           \
 179                     }                                                         \
 180                   /* If the real name is different add it also to the         \
 181                      aliases.  This means that there is a duplication         \
 182                      in the alias list but this is really the users           \
 183                      problem.  */                                             \
 184                   if (strcmp (old_result->h_name,                             \
 185                               tmp_result_buf.h_name) != 0)                    \
 186                     {                                                         \
 187                       ++newaliases;                                           \
 188                       newstrlen += strlen (tmp_result_buf.h_name) + 1;        \
 189                     }                                                         \
 190                                                                               \
 191                   /* Make sure bufferend is aligned.  */                      \
 192                   assert ((bufferend - (char *) 0) % sizeof (char *) == 0);   \
 193                                                                               \
 194                   /* Now we can check whether the buffer is large enough.     \
 195                      16 is the maximal size of the IP address.  */            \
 196                   if (bufferend + 16 + (naddrs + 2) * sizeof (char *)         \
 197                       + roundup (newstrlen, sizeof (char *))                  \
 198                       + (naliases + newaliases + 1) * sizeof (char *)         \
 199                       >= buffer + buflen)                                     \
 200                     {                                                         \
 201                       *errnop = ERANGE;                                       \
 202                       *herrnop = NETDB_INTERNAL;                              \
 203                       status = NSS_STATUS_TRYAGAIN;                           \
 204                       break;                                                  \
 205                     }                                                         \
 206                                                                               \
 207                   new_h_addr_list =                                           \
 208                     (char **) (bufferend                                      \
 209                                + roundup (newstrlen, sizeof (char *))         \
 210                                + 16);                                         \
 211                   new_h_aliases =                                             \
 212                     (char **) ((char *) new_h_addr_list                       \
 213                                + (naddrs + 2) * sizeof (char *));             \
 214                                                                               \
 215                   /* Copy the old data in the new arrays.  */                 \
 216                   for (cnt = 0; cnt < naddrs; ++cnt)                          \
 217                     new_h_addr_list[cnt] = old_result->h_addr_list[cnt];      \
 218                                                                               \
 219                   for (cnt = 0; cnt < naliases; ++cnt)                        \
 220                     new_h_aliases[cnt] = old_result->h_aliases[cnt];          \
 221                                                                               \
 222                   /* Store the new strings.  */                               \
 223                   cnt = 0;                                                    \
 224                   while (tmp_result_buf.h_aliases[cnt] != NULL)               \
 225                     {                                                         \
 226                       new_h_aliases[naliases++] = bufferend;                  \
 227                       bufferend = (__stpcpy (bufferend,                       \
 228                                              tmp_result_buf.h_aliases[cnt])   \
 229                                    + 1);                                      \
 230                       ++cnt;                                                  \
 231                     }                                                         \
 232                                                                               \
 233                   if (cnt < newaliases)                                       \
 234                     {                                                         \
 235                       new_h_aliases[naliases++] = bufferend;                  \
 236                       bufferend = __stpcpy (bufferend,                        \
 237                                             tmp_result_buf.h_name) + 1;       \
 238                     }                                                         \
 239                                                                               \
 240                   /* Final NULL pointer.  */                                  \
 241                   new_h_aliases[naliases] = NULL;                             \
 242                                                                               \
 243                   /* Round up the buffer end address.  */                     \
 244                   bufferend += (sizeof (char *)                               \
 245                                 - ((bufferend - (char *) 0)                   \
 246                                    % sizeof (char *))) % sizeof (char *);     \
 247                                                                               \
 248                   /* Now the new address.  */                                 \
 249                   new_h_addr_list[naddrs++] =                                 \
 250                     memcpy (bufferend, tmp_result_buf.h_addr,                 \
 251                             tmp_result_buf.h_length);                         \
 252                                                                               \
 253                   /* Also here a final NULL pointer.  */                      \
 254                   new_h_addr_list[naddrs] = NULL;                             \
 255                                                                               \
 256                   /* Store the new array pointers.  */                        \
 257                   old_result->h_aliases = new_h_aliases;                      \
 258                   old_result->h_addr_list = new_h_addr_list;                  \
 259                                                                               \
 260                   /* Compute the new buffer end.  */                          \
 261                   bufferend = (char *) &new_h_aliases[naliases + 1];          \
 262                   assert (bufferend <= buffer + buflen);                      \
 263                                                                               \
 264                   result = old_result;                                        \
 265                 }                                                             \
 266             }                                                                 \
 267                                                                               \
 268           if (status != NSS_STATUS_TRYAGAIN)                                  \
 269             status = NSS_STATUS_SUCCESS;                                      \
 270         }                                                                     \
 271                                                                               \
 272                                                                               \
 273       if (! keep_stream)                                                      \
 274         internal_endent ();                                                   \
 275     }                                                                         \
 276                                                                               \
 277   __libc_lock_unlock (lock);                                                  \
 278                                                                               \
 279   return status;                                                              \
 280 }
 281
 282
 283 #define EXTRA_ARGS_VALUE \
 284   , ((_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET),                    \
 285   ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0)
 286 #include "files-XXX.c"
 287 HOST_DB_LOOKUP (hostbyname, ,,
 288                 {
 289                   LOOKUP_NAME_CASE (h_name, h_aliases)
 290                 }, const char *name)
 291
 292
 293 #undef EXTRA_ARGS_VALUE
 294 /* XXX Is using _res to determine whether we want to convert IPv4 addresses
 295    to IPv6 addresses really the right thing to do?  */
 296 #define EXTRA_ARGS_VALUE \
 297   , af, ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0)
 298 HOST_DB_LOOKUP (hostbyname2, ,,
 299                 {
 300                   LOOKUP_NAME_CASE (h_name, h_aliases)
 301                 }, const char *name, int af)
 302
 303 #undef EXTRA_ARGS_VALUE
 304 /* We only need to consider IPv4 mapped addresses if the input to the
 305    gethostbyaddr() function is an IPv6 address.  */
 306 #define EXTRA_ARGS_VALUE \
 307   , af, (len == IN6ADDRSZ ? AI_V4MAPPED : 0)
 308 DB_LOOKUP (hostbyaddr, ,,
 309            {
 310              if (result->h_length == (int) len
 311                  && ! memcmp (addr, result->h_addr_list[0], len))
 312                break;
 313            }, const void *addr, socklen_t len, int af)