resolv/nss_dns/dns-network.c

   1 /* Copyright (C) 1996, 1997, 1998, 1999, 2002, 2004
   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, lookup_method net_i);
 106
 107
 108 enum nss_status
 109 _nss_dns_getnetbyname_r (const char *name, struct netent *result,
 110                          char *buffer, size_t buflen, int *errnop,
 111                          int *herrnop)
 112 {
 113   /* Return entry for network with NAME.  */
 114   union
 115   {
 116     querybuf *buf;
 117     u_char *ptr;
 118   } net_buffer;
 119   querybuf *orig_net_buffer;
 120   int anslen;
 121   char *qbuf;
 122   enum nss_status status;
 123
 124   if (__res_maybe_init (&_res, 0) == -1)
 125     return NSS_STATUS_UNAVAIL;
 126
 127   qbuf = strdupa (name);
 128
 129   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 130
 131   anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 132                                1024, &net_buffer.ptr);
 133   if (anslen < 0)
 134     {
 135       /* Nothing found.  */
 136       *errnop = errno;
 137       if (net_buffer.buf != orig_net_buffer)
 138         free (net_buffer.buf);
 139       return (errno == ECONNREFUSED
 140               || errno == EPFNOSUPPORT
 141               || errno == EAFNOSUPPORT)
 142         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 143     }
 144
 145   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen, 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);
 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, BYADDR);
 222   if (net_buffer.buf != orig_net_buffer)
 223     free (net_buffer.buf);
 224   if (status == NSS_STATUS_SUCCESS)
 225     {
 226       /* Strip trailing zeros.  */
 227       unsigned int u_net = net; /* Maybe net should be unsigned?  */
 228
 229       while ((u_net & 0xff) == 0 && u_net != 0)
 230         u_net >>= 8;
 231       result->n_net = u_net;
 232     }
 233
 234   return status;
 235 }
 236
 237
 238 #undef offsetof
 239 #define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)
 240
 241 static enum nss_status
 242 getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 243              char *buffer, size_t buflen, lookup_method net_i)
 244 {
 245   /*
 246    * Find first satisfactory answer
 247    *
 248    *      answer --> +------------+  ( MESSAGE )
 249    *                 |   Header   |
 250    *                 +------------+
 251    *                 |  Question  | the question for the name server
 252    *                 +------------+
 253    *                 |   Answer   | RRs answering the question
 254    *                 +------------+
 255    *                 | Authority  | RRs pointing toward an authority
 256    *                 | Additional | RRs holding additional information
 257    *                 +------------+
 258    */
 259   struct net_data
 260   {
 261     char *aliases[MAX_NR_ALIASES];
 262     char linebuffer[0];
 263   } *net_data = (struct net_data *) buffer;
 264   int linebuflen = buflen - offsetof (struct net_data, linebuffer);
 265   const unsigned char *end_of_message = &answer->buf[anslen];
 266   const HEADER *header_pointer = &answer->hdr;
 267   /* #/records in the answer section.  */
 268   int answer_count =  ntohs (header_pointer->ancount);
 269   /* #/entries in the question section.  */
 270   int question_count = ntohs (header_pointer->qdcount);
 271   char *bp = net_data->linebuffer;
 272   const unsigned char *cp = &answer->buf[HFIXEDSZ];
 273   char **alias_pointer;
 274   int have_answer;
 275   char *ans;
 276   u_char packtmp[NS_MAXCDNAME];
 277
 278   if (question_count == 0)
 279     {
 280       /* FIXME: the Sun version uses for host name lookup an additional
 281          parameter for pointing to h_errno.  this is missing here.
 282          OSF/1 has a per-thread h_errno variable.  */
 283       if (header_pointer->aa != 0)
 284         {
 285           __set_h_errno (HOST_NOT_FOUND);
 286           return NSS_STATUS_NOTFOUND;
 287         }
 288       else
 289         {
 290           __set_h_errno (TRY_AGAIN);
 291           return NSS_STATUS_TRYAGAIN;
 292         }
 293     }
 294
 295   /* Skip the question part.  */
 296   while (question_count-- > 0)
 297     {
 298       int n = __dn_skipname (cp, end_of_message);
 299       if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
 300        {
 301          __set_h_errno (NO_RECOVERY);
 302          return NSS_STATUS_UNAVAIL;
 303        }
 304       cp += n + QFIXEDSZ;
 305     }
 306
 307   alias_pointer = result->n_aliases = &net_data->aliases[0];
 308   *alias_pointer = NULL;
 309   have_answer = 0;
 310   ans = NULL;
 311
 312   while (--answer_count >= 0 && cp < end_of_message)
 313     {
 314       int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
 315       int type, class;
 316
 317       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 318                             packtmp, sizeof packtmp);
 319       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 320         {
 321           if (errno == EMSGSIZE)
 322             {
 323               errno = ERANGE;
 324               return NSS_STATUS_TRYAGAIN;
 325             }
 326
 327           n = -1;
 328         }
 329
 330       if (n > 0 && bp[0] == '.')
 331         bp[0] = '\0';
 332
 333       if (n < 0 || res_dnok (bp) == 0)
 334         break;
 335       cp += n;
 336       ans = strdupa (bp);
 337       GETSHORT (type, cp);
 338       GETSHORT (class, cp);
 339       cp += INT32SZ;            /* TTL */
 340       GETSHORT (n, cp);
 341
 342       if (class == C_IN && type == T_PTR)
 343         {
 344           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 345                                 packtmp, sizeof packtmp);
 346           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 347             {
 348               if (errno == EMSGSIZE)
 349                 {
 350                   errno = ERANGE;
 351                   return NSS_STATUS_TRYAGAIN;
 352                 }
 353
 354               n = -1;
 355             }
 356
 357           if (n < 0 || !res_hnok (bp))
 358             {
 359               /* XXX What does this mean?  The original form from bind
 360                  returns NULL. Incrementing cp has no effect in any case.
 361                  What should I return here. ??? */
 362               cp += n;
 363               return NSS_STATUS_UNAVAIL;
 364             }
 365           cp += n;
 366          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
 367            {
 368              *alias_pointer++ = bp;
 369              n = strlen (bp) + 1;
 370              bp += n;
 371              linebuflen -= n;
 372              result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
 373              ++have_answer;
 374            }
 375         }
 376     }
 377
 378   if (have_answer)
 379     {
 380       *alias_pointer = NULL;
 381       switch (net_i)
 382         {
 383         case BYADDR:
 384           result->n_name = *result->n_aliases++;
 385           result->n_net = 0L;
 386           return NSS_STATUS_SUCCESS;
 387
 388         case BYNAME:
 389           {
 390             char **ap = result->n_aliases++;
 391             while (*ap != NULL)
 392               {
 393                 /* Check each alias name for being of the forms:
 394                    4.3.2.1.in-addr.arpa         = net 1.2.3.4
 395                    3.2.1.in-addr.arpa           = net 0.1.2.3
 396                    2.1.in-addr.arpa             = net 0.0.1.2
 397                    1.in-addr.arpa               = net 0.0.0.1
 398                 */
 399                 uint32_t val = 0;       /* Accumulator for n_net value.  */
 400                 unsigned int shift = 0; /* Which part we are parsing now.  */
 401                 const char *p = *ap; /* Consuming the string.  */
 402                 do
 403                   {
 404                     /* Match the leading 0 or 0[xX] base indicator.  */
 405                     unsigned int base = 10;
 406                     if (*p == '0' && p[1] != '.')
 407                       {
 408                         base = 8;
 409                         ++p;
 410                         if (*p == 'x' || *p == 'X')
 411                           {
 412                             base = 16;
 413                             ++p;
 414                             if (*p == '.')
 415                               break; /* No digit here.  Give up on alias.  */
 416                           }
 417                         if (*p == '\0')
 418                           break;
 419                       }
 420
 421                     uint32_t part = 0; /* Accumulates this part's number.  */
 422                     do
 423                       {
 424                         if (isdigit (*p) && (*p - '0' < base))
 425                           part = (part * base) + (*p - '0');
 426                         else if (base == 16 && isxdigit (*p))
 427                           part = (part << 4) + 10 + (tolower (*p) - 'a');
 428                         ++p;
 429                       } while (*p != '\0' && *p != '.');
 430
 431                     if (*p != '.')
 432                       break;    /* Bad form.  Give up on this name.  */
 433
 434                     /* Install this as the next more significant byte.  */
 435                     val |= part << shift;
 436                     shift += 8;
 437                     ++p;
 438
 439                     /* If we are out of digits now, there are two cases:
 440                        1. We are done with digits and now see "in-addr.arpa".
 441                        2. This is not the droid we are looking for.  */
 442                     if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
 443                       {
 444                         result->n_net = val;
 445                         return NSS_STATUS_SUCCESS;
 446                       }
 447
 448                     /* Keep going when we have seen fewer than 4 parts.  */
 449                   } while (shift < 32);
 450               }
 451           }
 452           break;
 453         }
 454     }
 455
 456   __set_h_errno (TRY_AGAIN);
 457   return NSS_STATUS_TRYAGAIN;
 458 }