resolv/nss_dns/dns-network.c

   1 /* Copyright (C) 1996-2013 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
   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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /* Parts of this file are plain copies of the file `getnetnamadr.c' from
  20    the bind package and it has the following copyright.  */
  21
  22 /* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
  23  *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
  24  *
  25  * Permission to use, copy, modify, and distribute this software for any
  26  * purpose with or without fee is hereby granted, provided that the above
  27  * copyright notice and this permission notice appear in all copies.
  28  */
  29 /*
  30  * Copyright (c) 1983, 1993
  31  *      The Regents of the University of California.  All rights reserved.
  32  *
  33  * Redistribution and use in source and binary forms, with or without
  34  * modification, are permitted provided that the following conditions
  35  * are met:
  36  * 1. Redistributions of source code must retain the above copyright
  37  *    notice, this list of conditions and the following disclaimer.
  38  * 2. Redistributions in binary form must reproduce the above copyright
  39  *    notice, this list of conditions and the following disclaimer in the
  40  *    documentation and/or other materials provided with the distribution.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #include <ctype.h>
  59 #include <errno.h>
  60 #include <netdb.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64
  65 #include "nsswitch.h"
  66 #include <arpa/inet.h>
  67
  68 /* Maximum number of aliases we allow.  */
  69 #define MAX_NR_ALIASES  48
  70
  71
  72 #if PACKETSZ > 65536
  73 # define MAXPACKET      PACKETSZ
  74 #else
  75 # define MAXPACKET      65536
  76 #endif
  77
  78
  79 typedef enum
  80 {
  81   BYADDR,
  82   BYNAME
  83 } lookup_method;
  84
  85
  86 /* We need this time later.  */
  87 typedef union querybuf
  88 {
  89   HEADER hdr;
  90   u_char buf[MAXPACKET];
  91 } querybuf;
  92
  93 /* These functions are defined in res_comp.c.  */
  94 #define NS_MAXCDNAME    255     /* maximum compressed domain name */
  95 extern int __ns_name_ntop (const u_char *, char *, size_t) __THROW;
  96 extern int __ns_name_unpack (const u_char *, const u_char *,
  97                              const u_char *, u_char *, size_t) __THROW;
  98
  99
 100 /* Prototypes for local functions.  */
 101 static enum nss_status getanswer_r (const querybuf *answer, int anslen,
 102                                     struct netent *result, char *buffer,
 103                                     size_t buflen, int *errnop, int *h_errnop,
 104                                     lookup_method net_i);
 105
 106
 107 enum nss_status
 108 _nss_dns_getnetbyname_r (const char *name, struct netent *result,
 109                          char *buffer, size_t buflen, int *errnop,
 110                          int *herrnop)
 111 {
 112   /* Return entry for network with NAME.  */
 113   union
 114   {
 115     querybuf *buf;
 116     u_char *ptr;
 117   } net_buffer;
 118   querybuf *orig_net_buffer;
 119   int anslen;
 120   char *qbuf;
 121   enum nss_status status;
 122
 123   if (__res_maybe_init (&_res, 0) == -1)
 124     return NSS_STATUS_UNAVAIL;
 125
 126   qbuf = strdupa (name);
 127
 128   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 129
 130   anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 131                                1024, &net_buffer.ptr, NULL, NULL, NULL);
 132   if (anslen < 0)
 133     {
 134       /* Nothing found.  */
 135       *errnop = errno;
 136       if (net_buffer.buf != orig_net_buffer)
 137         free (net_buffer.buf);
 138       return (errno == ECONNREFUSED
 139               || errno == EPFNOSUPPORT
 140               || errno == EAFNOSUPPORT)
 141         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 142     }
 143
 144   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
 145                         errnop, herrnop, BYNAME);
 146   if (net_buffer.buf != orig_net_buffer)
 147     free (net_buffer.buf);
 148   return status;
 149 }
 150
 151
 152 enum nss_status
 153 _nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
 154                          char *buffer, size_t buflen, int *errnop,
 155                          int *herrnop)
 156 {
 157   /* Return entry for network with NAME.  */
 158   enum nss_status status;
 159   union
 160   {
 161     querybuf *buf;
 162     u_char *ptr;
 163   } net_buffer;
 164   querybuf *orig_net_buffer;
 165   unsigned int net_bytes[4];
 166   char qbuf[MAXDNAME];
 167   int cnt, anslen;
 168   u_int32_t net2;
 169   int olderr = errno;
 170
 171   /* No net address lookup for IPv6 yet.  */
 172   if (type != AF_INET)
 173     return NSS_STATUS_UNAVAIL;
 174
 175   if (__res_maybe_init (&_res, 0) == -1)
 176     return NSS_STATUS_UNAVAIL;
 177
 178   net2 = (u_int32_t) net;
 179   for (cnt = 4; net2 != 0; net2 >>= 8)
 180     net_bytes[--cnt] = net2 & 0xff;
 181
 182   switch (cnt)
 183     {
 184     case 3:
 185       /* Class A network.  */
 186       sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
 187       break;
 188     case 2:
 189       /* Class B network.  */
 190       sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
 191       break;
 192     case 1:
 193       /* Class C network.  */
 194       sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 195                net_bytes[1]);
 196       break;
 197     case 0:
 198       /* Class D - E network.  */
 199       sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 200                net_bytes[1], net_bytes[0]);
 201       break;
 202     }
 203
 204   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 205
 206   anslen = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 207                               1024, &net_buffer.ptr, NULL, NULL, NULL);
 208   if (anslen < 0)
 209     {
 210       /* Nothing found.  */
 211       int err = errno;
 212       __set_errno (olderr);
 213       if (net_buffer.buf != orig_net_buffer)
 214         free (net_buffer.buf);
 215       return (err == ECONNREFUSED
 216               || err == EPFNOSUPPORT
 217               || err == EAFNOSUPPORT)
 218         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 219     }
 220
 221   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
 222                         errnop, herrnop, BYADDR);
 223   if (net_buffer.buf != orig_net_buffer)
 224     free (net_buffer.buf);
 225   if (status == NSS_STATUS_SUCCESS)
 226     {
 227       /* Strip trailing zeros.  */
 228       unsigned int u_net = net; /* Maybe net should be unsigned?  */
 229
 230       while ((u_net & 0xff) == 0 && u_net != 0)
 231         u_net >>= 8;
 232       result->n_net = u_net;
 233     }
 234
 235   return status;
 236 }
 237
 238
 239 #undef offsetof
 240 #define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)
 241
 242 static enum nss_status
 243 getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 244              char *buffer, size_t buflen, int *errnop, int *h_errnop,
 245              lookup_method net_i)
 246 {
 247   /*
 248    * Find first satisfactory answer
 249    *
 250    *      answer --> +------------+  ( MESSAGE )
 251    *                 |   Header   |
 252    *                 +------------+
 253    *                 |  Question  | the question for the name server
 254    *                 +------------+
 255    *                 |   Answer   | RRs answering the question
 256    *                 +------------+
 257    *                 | Authority  | RRs pointing toward an authority
 258    *                 | Additional | RRs holding additional information
 259    *                 +------------+
 260    */
 261   struct net_data
 262   {
 263     char *aliases[MAX_NR_ALIASES];
 264     char linebuffer[0];
 265   } *net_data;
 266
 267   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
 268   buffer += pad;
 269
 270   if (__builtin_expect (buflen < sizeof (*net_data) + pad, 0))
 271     {
 272       /* The buffer is too small.  */
 273     too_small:
 274       *errnop = ERANGE;
 275       *h_errnop = NETDB_INTERNAL;
 276       return NSS_STATUS_TRYAGAIN;
 277     }
 278   buflen -= pad;
 279
 280   net_data = (struct net_data *) buffer;
 281   int linebuflen = buflen - offsetof (struct net_data, linebuffer);
 282   if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
 283     linebuflen = INT_MAX;
 284   const unsigned char *end_of_message = &answer->buf[anslen];
 285   const HEADER *header_pointer = &answer->hdr;
 286   /* #/records in the answer section.  */
 287   int answer_count =  ntohs (header_pointer->ancount);
 288   /* #/entries in the question section.  */
 289   int question_count = ntohs (header_pointer->qdcount);
 290   char *bp = net_data->linebuffer;
 291   const unsigned char *cp = &answer->buf[HFIXEDSZ];
 292   char **alias_pointer;
 293   int have_answer;
 294   u_char packtmp[NS_MAXCDNAME];
 295
 296   if (question_count == 0)
 297     {
 298       /* FIXME: the Sun version uses for host name lookup an additional
 299          parameter for pointing to h_errno.  this is missing here.
 300          OSF/1 has a per-thread h_errno variable.  */
 301       if (header_pointer->aa != 0)
 302         {
 303           __set_h_errno (HOST_NOT_FOUND);
 304           return NSS_STATUS_NOTFOUND;
 305         }
 306       else
 307         {
 308           __set_h_errno (TRY_AGAIN);
 309           return NSS_STATUS_TRYAGAIN;
 310         }
 311     }
 312
 313   /* Skip the question part.  */
 314   while (question_count-- > 0)
 315     {
 316       int n = __dn_skipname (cp, end_of_message);
 317       if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
 318        {
 319          __set_h_errno (NO_RECOVERY);
 320          return NSS_STATUS_UNAVAIL;
 321        }
 322       cp += n + QFIXEDSZ;
 323     }
 324
 325   alias_pointer = result->n_aliases = &net_data->aliases[0];
 326   *alias_pointer = NULL;
 327   have_answer = 0;
 328
 329   while (--answer_count >= 0 && cp < end_of_message)
 330     {
 331       int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
 332       int type, class;
 333
 334       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 335                             packtmp, sizeof packtmp);
 336       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 337         {
 338           if (errno == EMSGSIZE)
 339             goto too_small;
 340
 341           n = -1;
 342         }
 343
 344       if (n > 0 && bp[0] == '.')
 345         bp[0] = '\0';
 346
 347       if (n < 0 || res_dnok (bp) == 0)
 348         break;
 349       cp += n;
 350       GETSHORT (type, cp);
 351       GETSHORT (class, cp);
 352       cp += INT32SZ;            /* TTL */
 353       GETSHORT (n, cp);
 354
 355       if (class == C_IN && type == T_PTR)
 356         {
 357           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 358                                 packtmp, sizeof packtmp);
 359           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 360             {
 361               if (errno == EMSGSIZE)
 362                 goto too_small;
 363
 364               n = -1;
 365             }
 366
 367           if (n < 0 || !res_hnok (bp))
 368             {
 369               /* XXX What does this mean?  The original form from bind
 370                  returns NULL. Incrementing cp has no effect in any case.
 371                  What should I return here. ??? */
 372               cp += n;
 373               return NSS_STATUS_UNAVAIL;
 374             }
 375           cp += n;
 376          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
 377            {
 378              *alias_pointer++ = bp;
 379              n = strlen (bp) + 1;
 380              bp += n;
 381              linebuflen -= n;
 382              result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
 383              ++have_answer;
 384            }
 385         }
 386     }
 387
 388   if (have_answer)
 389     {
 390       *alias_pointer = NULL;
 391       switch (net_i)
 392         {
 393         case BYADDR:
 394           result->n_name = *result->n_aliases++;
 395           result->n_net = 0L;
 396           return NSS_STATUS_SUCCESS;
 397
 398         case BYNAME:
 399           {
 400             char **ap = result->n_aliases++;
 401             while (*ap != NULL)
 402               {
 403                 /* Check each alias name for being of the forms:
 404                    4.3.2.1.in-addr.arpa         = net 1.2.3.4
 405                    3.2.1.in-addr.arpa           = net 0.1.2.3
 406                    2.1.in-addr.arpa             = net 0.0.1.2
 407                    1.in-addr.arpa               = net 0.0.0.1
 408                 */
 409                 uint32_t val = 0;       /* Accumulator for n_net value.  */
 410                 unsigned int shift = 0; /* Which part we are parsing now.  */
 411                 const char *p = *ap; /* Consuming the string.  */
 412                 do
 413                   {
 414                     /* Match the leading 0 or 0[xX] base indicator.  */
 415                     unsigned int base = 10;
 416                     if (*p == '0' && p[1] != '.')
 417                       {
 418                         base = 8;
 419                         ++p;
 420                         if (*p == 'x' || *p == 'X')
 421                           {
 422                             base = 16;
 423                             ++p;
 424                             if (*p == '.')
 425                               break; /* No digit here.  Give up on alias.  */
 426                           }
 427                         if (*p == '\0')
 428                           break;
 429                       }
 430
 431                     uint32_t part = 0; /* Accumulates this part's number.  */
 432                     do
 433                       {
 434                         if (isdigit (*p) && (*p - '0' < base))
 435                           part = (part * base) + (*p - '0');
 436                         else if (base == 16 && isxdigit (*p))
 437                           part = (part << 4) + 10 + (tolower (*p) - 'a');
 438                         ++p;
 439                       } while (*p != '\0' && *p != '.');
 440
 441                     if (*p != '.')
 442                       break;    /* Bad form.  Give up on this name.  */
 443
 444                     /* Install this as the next more significant byte.  */
 445                     val |= part << shift;
 446                     shift += 8;
 447                     ++p;
 448
 449                     /* If we are out of digits now, there are two cases:
 450                        1. We are done with digits and now see "in-addr.arpa".
 451                        2. This is not the droid we are looking for.  */
 452                     if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
 453                       {
 454                         result->n_net = val;
 455                         return NSS_STATUS_SUCCESS;
 456                       }
 457
 458                     /* Keep going when we have seen fewer than 4 parts.  */
 459                   } while (shift < 32);
 460               }
 461           }
 462           break;
 463         }
 464     }
 465
 466   __set_h_errno (TRY_AGAIN);
 467   return NSS_STATUS_TRYAGAIN;
 468 }