nss/digits_dots.c

   1 /* Copyright (C) 1997-2021 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 <assert.h>
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <ctype.h>
  23 #include <wctype.h>
  24 #include <resolv/resolv-internal.h>
  25 #include <resolv/resolv_context.h>
  26 #include <netdb.h>
  27 #include <arpa/inet.h>
  28 #include "nsswitch.h"
  29
  30 #ifdef USE_NSCD
  31 # include <nscd/nscd_proto.h>
  32 #endif
  33
  34 int
  35 __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,
  36                             char **buffer, size_t *buffer_size,
  37                             size_t buflen, struct hostent **result,
  38                             enum nss_status *status, int af, int *h_errnop)
  39 {
  40   /* We have to test for the use of IPv6 which can only be done by
  41      examining `_res'.  */
  42   struct resolv_context *ctx = __resolv_context_get ();
  43   if (ctx == NULL)
  44     {
  45       if (h_errnop)
  46         *h_errnop = NETDB_INTERNAL;
  47       if (buffer_size == NULL)
  48         *status = NSS_STATUS_TRYAGAIN;
  49       else
  50         *result = NULL;
  51       return -1;
  52     }
  53   int ret = __nss_hostname_digits_dots_context
  54     (ctx, name, resbuf, buffer, buffer_size, buflen,
  55      result, status, af, h_errnop);
  56   __resolv_context_put (ctx);
  57   return ret;
  58 }
  59
  60 int
  61 __nss_hostname_digits_dots_context (struct resolv_context *ctx,
  62                                     const char *name, struct hostent *resbuf,
  63                                     char **buffer, size_t *buffer_size,
  64                                     size_t buflen, struct hostent **result,
  65                                     enum nss_status *status, int af, int *h_errnop)
  66 {
  67   int save;
  68
  69   /*
  70    * disallow names consisting only of digits/dots, unless
  71    * they end in a dot.
  72    */
  73   if (isdigit (name[0]) || isxdigit (name[0]) || name[0] == ':')
  74     {
  75       const char *cp;
  76       char *hostname;
  77       typedef unsigned char host_addr_t[16];
  78       host_addr_t *host_addr;
  79       typedef char *host_addr_list_t[2];
  80       host_addr_list_t *h_addr_ptrs;
  81       char **h_alias_ptr;
  82       size_t size_needed;
  83       int addr_size;
  84
  85       switch (af)
  86         {
  87         case AF_INET:
  88           addr_size = INADDRSZ;
  89           break;
  90
  91         case AF_INET6:
  92           addr_size = IN6ADDRSZ;
  93           break;
  94
  95         default:
  96           af = res_use_inet6 () ? AF_INET6 : AF_INET;
  97           addr_size = af == AF_INET6 ? IN6ADDRSZ : INADDRSZ;
  98           break;
  99         }
 100
 101       size_needed = (sizeof (*host_addr)
 102                      + sizeof (*h_addr_ptrs)
 103                      + sizeof (*h_alias_ptr) + strlen (name) + 1);
 104
 105       if (buffer_size == NULL)
 106         {
 107           if (buflen < size_needed)
 108             {
 109               *status = NSS_STATUS_TRYAGAIN;
 110               if (h_errnop != NULL)
 111                 *h_errnop = NETDB_INTERNAL;
 112               __set_errno (ERANGE);
 113               goto done;
 114             }
 115         }
 116       else if (buffer_size != NULL && *buffer_size < size_needed)
 117         {
 118           char *new_buf;
 119           *buffer_size = size_needed;
 120           new_buf = (char *) realloc (*buffer, *buffer_size);
 121
 122           if (new_buf == NULL)
 123             {
 124               save = errno;
 125               free (*buffer);
 126               *buffer = NULL;
 127               *buffer_size = 0;
 128               __set_errno (save);
 129               if (h_errnop != NULL)
 130                 *h_errnop = NETDB_INTERNAL;
 131               *result = NULL;
 132               goto done;
 133             }
 134           *buffer = new_buf;
 135         }
 136
 137       memset (*buffer, '\0', size_needed);
 138
 139       host_addr = (host_addr_t *) *buffer;
 140       h_addr_ptrs = (host_addr_list_t *)
 141         ((char *) host_addr + sizeof (*host_addr));
 142       h_alias_ptr = (char **) ((char *) h_addr_ptrs + sizeof (*h_addr_ptrs));
 143       hostname = (char *) h_alias_ptr + sizeof (*h_alias_ptr);
 144
 145       if (isdigit (name[0]))
 146         {
 147           for (cp = name;; ++cp)
 148             {
 149               if (*cp == '\0')
 150                 {
 151                   int ok;
 152
 153                   if (*--cp == '.')
 154                     break;
 155
 156                   /* All-numeric, no dot at the end. Fake up a hostent as if
 157                      we'd actually done a lookup.  What if someone types
 158                      255.255.255.255?  The test below will succeed
 159                      spuriously... ???  */
 160                   if (af == AF_INET)
 161                     ok = __inet_aton_exact (name, (struct in_addr *) host_addr);
 162                   else
 163                     {
 164                       assert (af == AF_INET6);
 165                       ok = inet_pton (af, name, host_addr) > 0;
 166                     }
 167                   if (! ok)
 168                     {
 169                       *h_errnop = HOST_NOT_FOUND;
 170                       if (buffer_size == NULL)
 171                         *status = NSS_STATUS_NOTFOUND;
 172                       else
 173                         *result = NULL;
 174                       goto done;
 175                     }
 176
 177                   resbuf->h_name = strcpy (hostname, name);
 178                   h_alias_ptr[0] = NULL;
 179                   resbuf->h_aliases = h_alias_ptr;
 180                   (*h_addr_ptrs)[0] = (char *) host_addr;
 181                   (*h_addr_ptrs)[1] = NULL;
 182                   resbuf->h_addr_list = *h_addr_ptrs;
 183                   if (af == AF_INET && res_use_inet6 ())
 184                     {
 185                       /* We need to change the IP v4 address into the
 186                          IP v6 address.  */
 187                       char tmp[INADDRSZ];
 188                       char *p = (char *) host_addr;
 189                       int i;
 190
 191                       /* Save a copy of the IP v4 address. */
 192                       memcpy (tmp, host_addr, INADDRSZ);
 193                       /* Mark this ipv6 addr as a mapped ipv4. */
 194                       for (i = 0; i < 10; i++)
 195                         *p++ = 0x00;
 196                       *p++ = 0xff;
 197                       *p++ = 0xff;
 198                       /* Copy the IP v4 address. */
 199                       memcpy (p, tmp, INADDRSZ);
 200                       resbuf->h_addrtype = AF_INET6;
 201                       resbuf->h_length = IN6ADDRSZ;
 202                     }
 203                   else
 204                     {
 205                       resbuf->h_addrtype = af;
 206                       resbuf->h_length = addr_size;
 207                     }
 208                   if (h_errnop != NULL)
 209                     *h_errnop = NETDB_SUCCESS;
 210                   if (buffer_size == NULL)
 211                     *status = NSS_STATUS_SUCCESS;
 212                   else
 213                     *result = resbuf;
 214                   goto done;
 215                 }
 216
 217               if (!isdigit (*cp) && *cp != '.')
 218                 break;
 219             }
 220         }
 221
 222       if ((isxdigit (name[0]) && strchr (name, ':') != NULL) || name[0] == ':')
 223         {
 224           switch (af)
 225             {
 226             default:
 227               af = res_use_inet6 () ? AF_INET6 : AF_INET;
 228               if (af == AF_INET6)
 229                 {
 230                   addr_size = IN6ADDRSZ;
 231                   break;
 232                 }
 233               /* FALLTHROUGH */
 234
 235             case AF_INET:
 236               /* This is not possible.  We cannot represent an IPv6 address
 237                  in an `struct in_addr' variable.  */
 238               *h_errnop = HOST_NOT_FOUND;
 239               if (buffer_size == NULL)
 240                 *status = NSS_STATUS_NOTFOUND;
 241               else
 242                 *result = NULL;
 243               goto done;
 244
 245             case AF_INET6:
 246               addr_size = IN6ADDRSZ;
 247               break;
 248             }
 249
 250           for (cp = name;; ++cp)
 251             {
 252               if (!*cp)
 253                 {
 254                   if (*--cp == '.')
 255                     break;
 256
 257                   /* All-IPv6-legal, no dot at the end. Fake up a
 258                      hostent as if we'd actually done a lookup.  */
 259                   if (inet_pton (AF_INET6, name, host_addr) <= 0)
 260                     {
 261                       *h_errnop = HOST_NOT_FOUND;
 262                       if (buffer_size == NULL)
 263                         *status = NSS_STATUS_NOTFOUND;
 264                       else
 265                         *result = NULL;
 266                       goto done;
 267                     }
 268
 269                   resbuf->h_name = strcpy (hostname, name);
 270                   h_alias_ptr[0] = NULL;
 271                   resbuf->h_aliases = h_alias_ptr;
 272                   (*h_addr_ptrs)[0] = (char *) host_addr;
 273                   (*h_addr_ptrs)[1] = (char *) 0;
 274                   resbuf->h_addr_list = *h_addr_ptrs;
 275                   resbuf->h_addrtype = AF_INET6;
 276                   resbuf->h_length = addr_size;
 277                   *h_errnop = NETDB_SUCCESS;
 278                   if (buffer_size == NULL)
 279                     *status = NSS_STATUS_SUCCESS;
 280                   else
 281                     *result = resbuf;
 282                   goto done;
 283                 }
 284
 285               if (!isxdigit (*cp) && *cp != ':' && *cp != '.')
 286                 break;
 287             }
 288         }
 289     }
 290
 291   return 0;
 292
 293 done:
 294   return 1;
 295 }
 296 libc_hidden_def (__nss_hostname_digits_dots)