resolv/nss_dns/dns-network.c

   1 /* Copyright (C) 1996, 1997, 1998, 1999, 2002, 2004, 2007, 2008
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
   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 /* Parts of this file are plain copies of the file `getnetnamadr.c' from
  22    the bind package and it has the following copyright.  */
  23
  24 /* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
  25  *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
  26  *
  27  * Permission to use, copy, modify, and distribute this software for any
  28  * purpose with or without fee is hereby granted, provided that the above
  29  * copyright notice and this permission notice appear in all copies.
  30  */
  31 /*
  32  * Copyright (c) 1983, 1993
  33  *      The Regents of the University of California.  All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  */
  59
  60 #include <ctype.h>
  61 #include <errno.h>
  62 #include <netdb.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66
  67 #include "nsswitch.h"
  68 #include <arpa/inet.h>
  69
  70 /* Maximum number of aliases we allow.  */
  71 #define MAX_NR_ALIASES  48
  72
  73
  74 #if PACKETSZ > 65536
  75 # define MAXPACKET      PACKETSZ
  76 #else
  77 # define MAXPACKET      65536
  78 #endif
  79
  80
  81 typedef enum
  82 {
  83   BYADDR,
  84   BYNAME
  85 } lookup_method;
  86
  87
  88 /* We need this time later.  */
  89 typedef union querybuf
  90 {
  91   HEADER hdr;
  92   u_char buf[MAXPACKET];
  93 } querybuf;
  94
  95 /* These functions are defined in res_comp.c.  */
  96 #define NS_MAXCDNAME    255     /* maximum compressed domain name */
  97 extern int __ns_name_ntop (const u_char *, char *, size_t) __THROW;
  98 extern int __ns_name_unpack (const u_char *, const u_char *,
  99                              const u_char *, u_char *, size_t) __THROW;
 100
 101
 102 /* Prototypes for local functions.  */
 103 static enum nss_status getanswer_r (const querybuf *answer, int anslen,
 104                                     struct netent *result, char *buffer,
 105                                     size_t buflen, int *errnop, int *h_errnop,
 106                                     lookup_method net_i);
 107
 108
 109 enum nss_status
 110 _nss_dns_getnetbyname_r (const char *name, struct netent *result,
 111                          char *buffer, size_t buflen, int *errnop,
 112                          int *herrnop)
 113 {
 114   /* Return entry for network with NAME.  */
 115   union
 116   {
 117     querybuf *buf;
 118     u_char *ptr;
 119   } net_buffer;
 120   querybuf *orig_net_buffer;
 121   int anslen;
 122   char *qbuf;
 123   enum nss_status status;
 124
 125   if (__res_maybe_init (&_res, 0) == -1)
 126     return NSS_STATUS_UNAVAIL;
 127
 128   qbuf = strdupa (name);
 129
 130   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 131
 132   anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 133                                1024, &net_buffer.ptr, NULL, NULL, NULL);
 134   if (anslen < 0)
 135     {
 136       /* Nothing found.  */
 137       *errnop = errno;
 138       if (net_buffer.buf != orig_net_buffer)
 139         free (net_buffer.buf);
 140       return (errno == ECONNREFUSED
 141               || errno == EPFNOSUPPORT
 142               || errno == EAFNOSUPPORT)
 143         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 144     }
 145
 146   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
 147                         errnop, herrnop, BYNAME);
 148   if (net_buffer.buf != orig_net_buffer)
 149     free (net_buffer.buf);
 150   return status;
 151 }
 152
 153
 154 enum nss_status
 155 _nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
 156                          char *buffer, size_t buflen, int *errnop,
 157                          int *herrnop)
 158 {
 159   /* Return entry for network with NAME.  */
 160   enum nss_status status;
 161   union
 162   {
 163     querybuf *buf;
 164     u_char *ptr;
 165   } net_buffer;
 166   querybuf *orig_net_buffer;
 167   unsigned int net_bytes[4];
 168   char qbuf[MAXDNAME];
 169   int cnt, anslen;
 170   u_int32_t net2;
 171   int olderr = errno;
 172
 173   /* No net address lookup for IPv6 yet.  */
 174   if (type != AF_INET)
 175     return NSS_STATUS_UNAVAIL;
 176
 177   if (__res_maybe_init (&_res, 0) == -1)
 178     return NSS_STATUS_UNAVAIL;
 179
 180   net2 = (u_int32_t) net;
 181   for (cnt = 4; net2 != 0; net2 >>= 8)
 182     net_bytes[--cnt] = net2 & 0xff;
 183
 184   switch (cnt)
 185     {
 186     case 3:
 187       /* Class A network.  */
 188       sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
 189       break;
 190     case 2:
 191       /* Class B network.  */
 192       sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
 193       break;
 194     case 1:
 195       /* Class C network.  */
 196       sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 197                net_bytes[1]);
 198       break;
 199     case 0:
 200       /* Class D - E network.  */
 201       sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 202                net_bytes[1], net_bytes[0]);
 203       break;
 204     }
 205
 206   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 207
 208   anslen = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 209                               1024, &net_buffer.ptr, NULL, NULL, NULL);
 210   if (anslen < 0)
 211     {
 212       /* Nothing found.  */
 213       int err = errno;
 214       __set_errno (olderr);
 215       if (net_buffer.buf != orig_net_buffer)
 216         free (net_buffer.buf);
 217       return (err == ECONNREFUSED
 218               || err == EPFNOSUPPORT
 219               || err == EAFNOSUPPORT)
 220         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 221     }
 222
 223   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
 224                         errnop, herrnop, BYADDR);
 225   if (net_buffer.buf != orig_net_buffer)
 226     free (net_buffer.buf);
 227   if (status == NSS_STATUS_SUCCESS)
 228     {
 229       /* Strip trailing zeros.  */
 230       unsigned int u_net = net; /* Maybe net should be unsigned?  */
 231
 232       while ((u_net & 0xff) == 0 && u_net != 0)
 233         u_net >>= 8;
 234       result->n_net = u_net;
 235     }
 236
 237   return status;
 238 }
 239
 240
 241 #undef offsetof
 242 #define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)
 243
 244 static enum nss_status
 245 getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 246              char *buffer, size_t buflen, int *errnop, int *h_errnop,
 247              lookup_method net_i)
 248 {
 249   /*
 250    * Find first satisfactory answer
 251    *
 252    *      answer --> +------------+  ( MESSAGE )
 253    *                 |   Header   |
 254    *                 +------------+
 255    *                 |  Question  | the question for the name server
 256    *                 +------------+
 257    *                 |   Answer   | RRs answering the question
 258    *                 +------------+
 259    *                 | Authority  | RRs pointing toward an authority
 260    *                 | Additional | RRs holding additional information
 261    *                 +------------+
 262    */
 263   struct net_data
 264   {
 265     char *aliases[MAX_NR_ALIASES];
 266     char linebuffer[0];
 267   } *net_data;
 268
 269   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
 270   buffer += pad;
 271
 272   if (__builtin_expect (buflen < sizeof (*net_data) + pad, 0))
 273     {
 274       /* The buffer is too small.  */
 275     too_small:
 276       *errnop = ERANGE;
 277       *h_errnop = NETDB_INTERNAL;
 278       return NSS_STATUS_TRYAGAIN;
 279     }
 280   buflen -= pad;
 281
 282   net_data = (struct net_data *) buffer;
 283   int linebuflen = buflen - offsetof (struct net_data, linebuffer);
 284   if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
 285     linebuflen = INT_MAX;
 286   const unsigned char *end_of_message = &answer->buf[anslen];
 287   const HEADER *header_pointer = &answer->hdr;
 288   /* #/records in the answer section.  */
 289   int answer_count =  ntohs (header_pointer->ancount);
 290   /* #/entries in the question section.  */
 291   int question_count = ntohs (header_pointer->qdcount);
 292   char *bp = net_data->linebuffer;
 293   const unsigned char *cp = &answer->buf[HFIXEDSZ];
 294   char **alias_pointer;
 295   int have_answer;
 296   char *ans;
 297   u_char packtmp[NS_MAXCDNAME];
 298
 299   if (question_count == 0)
 300     {
 301       /* FIXME: the Sun version uses for host name lookup an additional
 302          parameter for pointing to h_errno.  this is missing here.
 303          OSF/1 has a per-thread h_errno variable.  */
 304       if (header_pointer->aa != 0)
 305         {
 306           __set_h_errno (HOST_NOT_FOUND);
 307           return NSS_STATUS_NOTFOUND;
 308         }
 309       else
 310         {
 311           __set_h_errno (TRY_AGAIN);
 312           return NSS_STATUS_TRYAGAIN;
 313         }
 314     }
 315
 316   /* Skip the question part.  */
 317   while (question_count-- > 0)
 318     {
 319       int n = __dn_skipname (cp, end_of_message);
 320       if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
 321        {
 322          __set_h_errno (NO_RECOVERY);
 323          return NSS_STATUS_UNAVAIL;
 324        }
 325       cp += n + QFIXEDSZ;
 326     }
 327
 328   alias_pointer = result->n_aliases = &net_data->aliases[0];
 329   *alias_pointer = NULL;
 330   have_answer = 0;
 331   ans = NULL;
 332
 333   while (--answer_count >= 0 && cp < end_of_message)
 334     {
 335       int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
 336       int type, class;
 337
 338       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 339                             packtmp, sizeof packtmp);
 340       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 341         {
 342           if (errno == EMSGSIZE)
 343             goto too_small;
 344
 345           n = -1;
 346         }
 347
 348       if (n > 0 && bp[0] == '.')
 349         bp[0] = '\0';
 350
 351       if (n < 0 || res_dnok (bp) == 0)
 352         break;
 353       cp += n;
 354       ans = strdupa (bp);
 355       GETSHORT (type, cp);
 356       GETSHORT (class, cp);
 357       cp += INT32SZ;            /* TTL */
 358       GETSHORT (n, cp);
 359
 360       if (class == C_IN && type == T_PTR)
 361         {
 362           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 363                                 packtmp, sizeof packtmp);
 364           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 365             {
 366               if (errno == EMSGSIZE)
 367                 goto too_small;
 368
 369               n = -1;
 370             }
 371
 372           if (n < 0 || !res_hnok (bp))
 373             {
 374               /* XXX What does this mean?  The original form from bind
 375                  returns NULL. Incrementing cp has no effect in any case.
 376                  What should I return here. ??? */
 377               cp += n;
 378               return NSS_STATUS_UNAVAIL;
 379             }
 380           cp += n;
 381          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
 382            {
 383              *alias_pointer++ = bp;
 384              n = strlen (bp) + 1;
 385              bp += n;
 386              linebuflen -= n;
 387              result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
 388              ++have_answer;
 389            }
 390         }
 391     }
 392
 393   if (have_answer)
 394     {
 395       *alias_pointer = NULL;
 396       switch (net_i)
 397         {
 398         case BYADDR:
 399           result->n_name = *result->n_aliases++;
 400           result->n_net = 0L;
 401           return NSS_STATUS_SUCCESS;
 402
 403         case BYNAME:
 404           {
 405             char **ap = result->n_aliases++;
 406             while (*ap != NULL)
 407               {
 408                 /* Check each alias name for being of the forms:
 409                    4.3.2.1.in-addr.arpa         = net 1.2.3.4
 410                    3.2.1.in-addr.arpa           = net 0.1.2.3
 411                    2.1.in-addr.arpa             = net 0.0.1.2
 412                    1.in-addr.arpa               = net 0.0.0.1
 413                 */
 414                 uint32_t val = 0;       /* Accumulator for n_net value.  */
 415                 unsigned int shift = 0; /* Which part we are parsing now.  */
 416                 const char *p = *ap; /* Consuming the string.  */
 417                 do
 418                   {
 419                     /* Match the leading 0 or 0[xX] base indicator.  */
 420                     unsigned int base = 10;
 421                     if (*p == '0' && p[1] != '.')
 422                       {
 423                         base = 8;
 424                         ++p;
 425                         if (*p == 'x' || *p == 'X')
 426                           {
 427                             base = 16;
 428                             ++p;
 429                             if (*p == '.')
 430                               break; /* No digit here.  Give up on alias.  */
 431                           }
 432                         if (*p == '\0')
 433                           break;
 434                       }
 435
 436                     uint32_t part = 0; /* Accumulates this part's number.  */
 437                     do
 438                       {
 439                         if (isdigit (*p) && (*p - '0' < base))
 440                           part = (part * base) + (*p - '0');
 441                         else if (base == 16 && isxdigit (*p))
 442                           part = (part << 4) + 10 + (tolower (*p) - 'a');
 443                         ++p;
 444                       } while (*p != '\0' && *p != '.');
 445
 446                     if (*p != '.')
 447                       break;    /* Bad form.  Give up on this name.  */
 448
 449                     /* Install this as the next more significant byte.  */
 450                     val |= part << shift;
 451                     shift += 8;
 452                     ++p;
 453
 454                     /* If we are out of digits now, there are two cases:
 455                        1. We are done with digits and now see "in-addr.arpa".
 456                        2. This is not the droid we are looking for.  */
 457                     if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
 458                       {
 459                         result->n_net = val;
 460                         return NSS_STATUS_SUCCESS;
 461                       }
 462
 463                     /* Keep going when we have seen fewer than 4 parts.  */
 464                   } while (shift < 32);
 465               }
 466           }
 467           break;
 468         }
 469     }
 470
 471   __set_h_errno (TRY_AGAIN);
 472   return NSS_STATUS_TRYAGAIN;
 473 }