resolv/nss_dns/dns-network.c

   1 /* Copyright (C) 1996, 1997, 1998, 1999, 2002 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 /* Parts of this file are plain copies of the file `getnetnamadr.c' from
  21    the bind package and it has the following copyright.  */
  22
  23 /* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
  24  *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
  25  *
  26  * Permission to use, copy, modify, and distribute this software for any
  27  * purpose with or without fee is hereby granted, provided that the above
  28  * copyright notice and this permission notice appear in all copies.
  29  */
  30 /*
  31  * Copyright (c) 1983, 1993
  32  *      The Regents of the University of California.  All rights reserved.
  33  *
  34  * Redistribution and use in source and binary forms, with or without
  35  * modification, are permitted provided that the following conditions
  36  * are met:
  37  * 1. Redistributions of source code must retain the above copyright
  38  *    notice, this list of conditions and the following disclaimer.
  39  * 2. Redistributions in binary form must reproduce the above copyright
  40  *    notice, this list of conditions and the following disclaimer in the
  41  *    documentation and/or other materials provided with the distribution.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  */
  58
  59 #include <ctype.h>
  60 #include <errno.h>
  61 #include <netdb.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65
  66 #include "nsswitch.h"
  67 #include <arpa/inet.h>
  68
  69 /* Maximum number of aliases we allow.  */
  70 #define MAX_NR_ALIASES  48
  71
  72
  73 #if PACKETSZ > 65536
  74 # define MAXPACKET      PACKETSZ
  75 #else
  76 # define MAXPACKET      65536
  77 #endif
  78
  79
  80 typedef enum
  81 {
  82   BYADDR,
  83   BYNAME
  84 } lookup_method;
  85
  86
  87 /* We need this time later.  */
  88 typedef union querybuf
  89 {
  90   HEADER hdr;
  91   u_char buf[MAXPACKET];
  92 } querybuf;
  93
  94 /* These functions are defined in res_comp.c.  */
  95 #define NS_MAXCDNAME    255     /* maximum compressed domain name */
  96 extern int __ns_name_ntop __P ((const u_char *, char *, size_t));
  97 extern int __ns_name_unpack __P ((const u_char *, const u_char *,
  98                                   const u_char *, u_char *, size_t));
  99
 100
 101 /* Prototypes for local functions.  */
 102 static enum nss_status getanswer_r (const querybuf *answer, int anslen,
 103                                     struct netent *result, char *buffer,
 104                                     size_t buflen, 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.options & RES_INIT) == 0 && __res_ninit (&_res) == -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);
 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, BYNAME);
 145   if (net_buffer.buf != orig_net_buffer)
 146     free (net_buffer.buf);
 147   return status;
 148 }
 149
 150
 151 enum nss_status
 152 _nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
 153                          char *buffer, size_t buflen, int *errnop,
 154                          int *herrnop)
 155 {
 156   /* Return entry for network with NAME.  */
 157   enum nss_status status;
 158   union
 159   {
 160     querybuf *buf;
 161     u_char *ptr;
 162   } net_buffer;
 163   querybuf *orig_net_buffer;
 164   unsigned int net_bytes[4];
 165   char qbuf[MAXDNAME];
 166   int cnt, anslen;
 167   u_int32_t net2;
 168   int olderr = errno;
 169
 170   /* No net address lookup for IPv6 yet.  */
 171   if (type != AF_INET)
 172     return NSS_STATUS_UNAVAIL;
 173
 174   if ((_res.options & RES_INIT) == 0 && __res_ninit (&_res) == -1)
 175     return NSS_STATUS_UNAVAIL;
 176
 177   net2 = (u_int32_t) net;
 178   for (cnt = 4; net2 != 0; net2 >>= 8)
 179     net_bytes[--cnt] = net2 & 0xff;
 180
 181   switch (cnt)
 182     {
 183     case 3:
 184       /* Class A network.  */
 185       sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
 186       break;
 187     case 2:
 188       /* Class B network.  */
 189       sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
 190       break;
 191     case 1:
 192       /* Class C network.  */
 193       sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 194                net_bytes[1]);
 195       break;
 196     case 0:
 197       /* Class D - E network.  */
 198       sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 199                net_bytes[1], net_bytes[0]);
 200       break;
 201     }
 202
 203   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 204
 205   anslen = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 206                               1024, &net_buffer.ptr);
 207   if (anslen < 0)
 208     {
 209       /* Nothing found.  */
 210       int err = errno;
 211       __set_errno (olderr);
 212       if (net_buffer.buf != orig_net_buffer)
 213         free (net_buffer.buf);
 214       return (err == ECONNREFUSED
 215               || err == EPFNOSUPPORT
 216               || err == EAFNOSUPPORT)
 217         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 218     }
 219
 220   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen, BYADDR);
 221   if (net_buffer.buf != orig_net_buffer)
 222     free (net_buffer.buf);
 223   if (status == NSS_STATUS_SUCCESS)
 224     {
 225       /* Strip trailing zeros.  */
 226       unsigned int u_net = net; /* Maybe net should be unsigned?  */
 227
 228       while ((u_net & 0xff) == 0 && u_net != 0)
 229         u_net >>= 8;
 230       result->n_net = u_net;
 231     }
 232
 233   return status;
 234 }
 235
 236
 237 #undef offsetof
 238 #define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)
 239
 240 static enum nss_status
 241 getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 242              char *buffer, size_t buflen, lookup_method net_i)
 243 {
 244   /*
 245    * Find first satisfactory answer
 246    *
 247    *      answer --> +------------+  ( MESSAGE )
 248    *                 |   Header   |
 249    *                 +------------+
 250    *                 |  Question  | the question for the name server
 251    *                 +------------+
 252    *                 |   Answer   | RRs answering the question
 253    *                 +------------+
 254    *                 | Authority  | RRs pointing toward an authority
 255    *                 | Additional | RRs holding additional information
 256    *                 +------------+
 257    */
 258   struct net_data
 259   {
 260     char *aliases[MAX_NR_ALIASES];
 261     char linebuffer[0];
 262   } *net_data = (struct net_data *) buffer;
 263   int linebuflen = buflen - offsetof (struct net_data, linebuffer);
 264   const char *end_of_message = &answer->buf[anslen];
 265   const HEADER *header_pointer = &answer->hdr;
 266   /* #/records in the answer section.  */
 267   int answer_count =  ntohs (header_pointer->ancount);
 268   /* #/entries in the question section.  */
 269   int question_count = ntohs (header_pointer->qdcount);
 270   char *bp = net_data->linebuffer;
 271   const char *cp = &answer->buf[HFIXEDSZ];
 272   char **alias_pointer;
 273   int have_answer;
 274   char *ans;
 275   u_char packtmp[NS_MAXCDNAME];
 276
 277   if (question_count == 0)
 278     {
 279       /* FIXME: the Sun version uses for host name lookup an additional
 280          parameter for pointing to h_errno.  this is missing here.
 281          OSF/1 has a per-thread h_errno variable.  */
 282       if (header_pointer->aa != 0)
 283         {
 284           __set_h_errno (HOST_NOT_FOUND);
 285           return NSS_STATUS_NOTFOUND;
 286         }
 287       else
 288         {
 289           __set_h_errno (TRY_AGAIN);
 290           return NSS_STATUS_TRYAGAIN;
 291         }
 292     }
 293
 294   /* Skip the question part.  */
 295   while (question_count-- > 0)
 296     {
 297       int n = __dn_skipname (cp, end_of_message);
 298       if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
 299        {
 300          __set_h_errno (NO_RECOVERY);
 301          return NSS_STATUS_UNAVAIL;
 302        }
 303       cp += n + QFIXEDSZ;
 304     }
 305
 306   alias_pointer = result->n_aliases = &net_data->aliases[0];
 307   *alias_pointer = NULL;
 308   have_answer = 0;
 309   ans = NULL;
 310
 311   while (--answer_count >= 0 && cp < end_of_message)
 312     {
 313       int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
 314       int type, class;
 315
 316       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 317                             packtmp, sizeof packtmp);
 318       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 319         {
 320           if (errno == EMSGSIZE)
 321             {
 322               errno = ERANGE;
 323               return NSS_STATUS_TRYAGAIN;
 324             }
 325
 326           n = -1;
 327         }
 328
 329       if (n > 0 && bp[0] == '.')
 330         bp[0] = '\0';
 331
 332       if (n < 0 || res_dnok (bp) == 0)
 333         break;
 334       cp += n;
 335       ans = strdupa (bp);
 336       GETSHORT (type, cp);
 337       GETSHORT (class, cp);
 338       cp += INT32SZ;            /* TTL */
 339       GETSHORT (n, cp);
 340
 341       if (class == C_IN && type == T_PTR)
 342         {
 343           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 344                                 packtmp, sizeof packtmp);
 345           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 346             {
 347               if (errno == EMSGSIZE)
 348                 {
 349                   errno = ERANGE;
 350                   return NSS_STATUS_TRYAGAIN;
 351                 }
 352
 353               n = -1;
 354             }
 355
 356           if (n < 0 || !res_hnok (bp))
 357             {
 358               /* XXX What does this mean?  The original form from bind
 359                  returns NULL. Incrementing cp has no effect in any case.
 360                  What should I return here. ??? */
 361               cp += n;
 362               return NSS_STATUS_UNAVAIL;
 363             }
 364           cp += n;
 365          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
 366            {
 367              *alias_pointer++ = bp;
 368              n = strlen (bp) + 1;
 369              bp += n;
 370              linebuflen -= n;
 371              result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
 372              ++have_answer;
 373            }
 374         }
 375     }
 376
 377   if (have_answer)
 378     {
 379       *alias_pointer = NULL;
 380       switch (net_i)
 381         {
 382         case BYADDR:
 383           result->n_name = *result->n_aliases++;
 384           result->n_net = 0L;
 385           return NSS_STATUS_SUCCESS;
 386
 387         case BYNAME:
 388           {
 389             char **ap = result->n_aliases++;
 390             while (*ap != NULL)
 391               {
 392                 /* Check each alias name for being of the forms:
 393                    4.3.2.1.in-addr.arpa         = net 1.2.3.4
 394                    3.2.1.in-addr.arpa           = net 0.1.2.3
 395                    2.1.in-addr.arpa             = net 0.0.1.2
 396                    1.in-addr.arpa               = net 0.0.0.1
 397                 */
 398                 uint32_t val = 0;       /* Accumulator for n_net value.  */
 399                 unsigned int shift = 0; /* Which part we are parsing now.  */
 400                 const char *p = *ap; /* Consuming the string.  */
 401                 do
 402                   {
 403                     /* Match the leading 0 or 0[xX] base indicator.  */
 404                     unsigned int base = 10;
 405                     if (*p == '0' && p[1] != '.')
 406                       {
 407                         base = 8;
 408                         ++p;
 409                         if (*p == 'x' || *p == 'X')
 410                           {
 411                             base = 16;
 412                             ++p;
 413                             if (*p == '.')
 414                               break; /* No digit here.  Give up on alias.  */
 415                           }
 416                         if (*p == '\0')
 417                           break;
 418                       }
 419
 420                     uint32_t part = 0; /* Accumulates this part's number.  */
 421                     do
 422                       {
 423                         if (isdigit (*p) && (*p - '0' < base))
 424                           part = (part * base) + (*p - '0');
 425                         else if (base == 16 && isxdigit (*p))
 426                           part = (part << 4) + 10 + (tolower (*p) - 'a');
 427                         ++p;
 428                       } while (*p != '\0' && *p != '.');
 429
 430                     if (*p != '.')
 431                       break;    /* Bad form.  Give up on this name.  */
 432
 433                     /* Install this as the next more significant byte.  */
 434                     val |= part << shift;
 435                     shift += 8;
 436                     ++p;
 437
 438                     /* If we are out of digits now, there are two cases:
 439                        1. We are done with digits and now see "in-addr.arpa".
 440                        2. This is not the droid we are looking for.  */
 441                     if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
 442                       {
 443                         result->n_net = val;
 444                         return NSS_STATUS_SUCCESS;
 445                       }
 446
 447                     /* Keep going when we have seen fewer than 4 parts.  */
 448                   } while (shift < 32);
 449               }
 450           }
 451           break;
 452         }
 453     }
 454
 455   __set_h_errno (TRY_AGAIN);
 456   return NSS_STATUS_TRYAGAIN;
 457 }