resolv/nss_dns/dns-network.c

   1 /* Copyright (C) 1996-2015 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 #include <stdint.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 (const u_char *, char *, size_t) __THROW;
  97 extern int __ns_name_unpack (const u_char *, const u_char *,
  98                              const u_char *, u_char *, size_t) __THROW;
  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, int *errnop, int *h_errnop,
 105                                     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, NULL, NULL, NULL, NULL);
 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,
 146                         errnop, herrnop, BYNAME);
 147   if (net_buffer.buf != orig_net_buffer)
 148     free (net_buffer.buf);
 149   return status;
 150 }
 151
 152
 153 enum nss_status
 154 _nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
 155                          char *buffer, size_t buflen, int *errnop,
 156                          int *herrnop)
 157 {
 158   /* Return entry for network with NAME.  */
 159   enum nss_status status;
 160   union
 161   {
 162     querybuf *buf;
 163     u_char *ptr;
 164   } net_buffer;
 165   querybuf *orig_net_buffer;
 166   unsigned int net_bytes[4];
 167   char qbuf[MAXDNAME];
 168   int cnt, anslen;
 169   u_int32_t net2;
 170   int olderr = errno;
 171
 172   /* No net address lookup for IPv6 yet.  */
 173   if (type != AF_INET)
 174     return NSS_STATUS_UNAVAIL;
 175
 176   if (__res_maybe_init (&_res, 0) == -1)
 177     return NSS_STATUS_UNAVAIL;
 178
 179   net2 = (u_int32_t) net;
 180   for (cnt = 4; net2 != 0; net2 >>= 8)
 181     net_bytes[--cnt] = net2 & 0xff;
 182
 183   switch (cnt)
 184     {
 185     case 3:
 186       /* Class A network.  */
 187       sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
 188       break;
 189     case 2:
 190       /* Class B network.  */
 191       sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
 192       break;
 193     case 1:
 194       /* Class C network.  */
 195       sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 196                net_bytes[1]);
 197       break;
 198     case 0:
 199       /* Class D - E network.  */
 200       sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
 201                net_bytes[1], net_bytes[0]);
 202       break;
 203     }
 204
 205   net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
 206
 207   anslen = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
 208                               1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
 209   if (anslen < 0)
 210     {
 211       /* Nothing found.  */
 212       int err = errno;
 213       __set_errno (olderr);
 214       if (net_buffer.buf != orig_net_buffer)
 215         free (net_buffer.buf);
 216       return (err == ECONNREFUSED
 217               || err == EPFNOSUPPORT
 218               || err == EAFNOSUPPORT)
 219         ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 220     }
 221
 222   status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
 223                         errnop, herrnop, BYADDR);
 224   if (net_buffer.buf != orig_net_buffer)
 225     free (net_buffer.buf);
 226   if (status == NSS_STATUS_SUCCESS)
 227     {
 228       /* Strip trailing zeros.  */
 229       unsigned int u_net = net; /* Maybe net should be unsigned?  */
 230
 231       while ((u_net & 0xff) == 0 && u_net != 0)
 232         u_net >>= 8;
 233       result->n_net = u_net;
 234     }
 235
 236   return status;
 237 }
 238
 239
 240 #undef offsetof
 241 #define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)
 242
 243 static enum nss_status
 244 getanswer_r (const querybuf *answer, int anslen, struct netent *result,
 245              char *buffer, size_t buflen, int *errnop, int *h_errnop,
 246              lookup_method net_i)
 247 {
 248   /*
 249    * Find first satisfactory answer
 250    *
 251    *      answer --> +------------+  ( MESSAGE )
 252    *                 |   Header   |
 253    *                 +------------+
 254    *                 |  Question  | the question for the name server
 255    *                 +------------+
 256    *                 |   Answer   | RRs answering the question
 257    *                 +------------+
 258    *                 | Authority  | RRs pointing toward an authority
 259    *                 | Additional | RRs holding additional information
 260    *                 +------------+
 261    */
 262   struct net_data
 263   {
 264     char *aliases[MAX_NR_ALIASES];
 265     char linebuffer[0];
 266   } *net_data;
 267
 268   uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
 269   buffer += pad;
 270
 271   if (__glibc_unlikely (buflen < sizeof (*net_data) + pad))
 272     {
 273       /* The buffer is too small.  */
 274     too_small:
 275       *errnop = ERANGE;
 276       *h_errnop = NETDB_INTERNAL;
 277       return NSS_STATUS_TRYAGAIN;
 278     }
 279   buflen -= pad;
 280
 281   net_data = (struct net_data *) buffer;
 282   int linebuflen = buflen - offsetof (struct net_data, linebuffer);
 283   if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
 284     linebuflen = INT_MAX;
 285   const unsigned char *end_of_message = &answer->buf[anslen];
 286   const HEADER *header_pointer = &answer->hdr;
 287   /* #/records in the answer section.  */
 288   int answer_count =  ntohs (header_pointer->ancount);
 289   /* #/entries in the question section.  */
 290   int question_count = ntohs (header_pointer->qdcount);
 291   char *bp = net_data->linebuffer;
 292   const unsigned char *cp = &answer->buf[HFIXEDSZ];
 293   char **alias_pointer;
 294   int have_answer;
 295   u_char packtmp[NS_MAXCDNAME];
 296
 297   if (question_count == 0)
 298     {
 299       /* FIXME: the Sun version uses for host name lookup an additional
 300          parameter for pointing to h_errno.  this is missing here.
 301          OSF/1 has a per-thread h_errno variable.  */
 302       if (header_pointer->aa != 0)
 303         {
 304           __set_h_errno (HOST_NOT_FOUND);
 305           return NSS_STATUS_NOTFOUND;
 306         }
 307       else
 308         {
 309           __set_h_errno (TRY_AGAIN);
 310           return NSS_STATUS_TRYAGAIN;
 311         }
 312     }
 313
 314   /* Skip the question part.  */
 315   while (question_count-- > 0)
 316     {
 317       int n = __dn_skipname (cp, end_of_message);
 318       if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
 319        {
 320          __set_h_errno (NO_RECOVERY);
 321          return NSS_STATUS_UNAVAIL;
 322        }
 323       cp += n + QFIXEDSZ;
 324     }
 325
 326   alias_pointer = result->n_aliases = &net_data->aliases[0];
 327   *alias_pointer = NULL;
 328   have_answer = 0;
 329
 330   while (--answer_count >= 0 && cp < end_of_message)
 331     {
 332       int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
 333       int type, class;
 334
 335       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 336                             packtmp, sizeof packtmp);
 337       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 338         {
 339           if (errno == EMSGSIZE)
 340             goto too_small;
 341
 342           n = -1;
 343         }
 344
 345       if (n > 0 && bp[0] == '.')
 346         bp[0] = '\0';
 347
 348       if (n < 0 || res_dnok (bp) == 0)
 349         break;
 350       cp += n;
 351       GETSHORT (type, cp);
 352       GETSHORT (class, cp);
 353       cp += INT32SZ;            /* TTL */
 354       GETSHORT (n, cp);
 355
 356       if (class == C_IN && type == T_PTR)
 357         {
 358           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 359                                 packtmp, sizeof packtmp);
 360           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 361             {
 362               if (errno == EMSGSIZE)
 363                 goto too_small;
 364
 365               n = -1;
 366             }
 367
 368           if (n < 0 || !res_hnok (bp))
 369             {
 370               /* XXX What does this mean?  The original form from bind
 371                  returns NULL. Incrementing cp has no effect in any case.
 372                  What should I return here. ??? */
 373               cp += n;
 374               return NSS_STATUS_UNAVAIL;
 375             }
 376           cp += n;
 377          if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
 378            {
 379              *alias_pointer++ = bp;
 380              n = strlen (bp) + 1;
 381              bp += n;
 382              linebuflen -= n;
 383              result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
 384              ++have_answer;
 385            }
 386         }
 387     }
 388
 389   if (have_answer)
 390     {
 391       *alias_pointer = NULL;
 392       switch (net_i)
 393         {
 394         case BYADDR:
 395           result->n_name = *result->n_aliases++;
 396           result->n_net = 0L;
 397           return NSS_STATUS_SUCCESS;
 398
 399         case BYNAME:
 400           {
 401             char **ap;
 402             for (ap = result->n_aliases; *ap != NULL; ++ap)
 403               {
 404                 /* Check each alias name for being of the forms:
 405                    4.3.2.1.in-addr.arpa         = net 1.2.3.4
 406                    3.2.1.in-addr.arpa           = net 0.1.2.3
 407                    2.1.in-addr.arpa             = net 0.0.1.2
 408                    1.in-addr.arpa               = net 0.0.0.1
 409                 */
 410                 uint32_t val = 0;       /* Accumulator for n_net value.  */
 411                 unsigned int shift = 0; /* Which part we are parsing now.  */
 412                 const char *p = *ap; /* Consuming the string.  */
 413                 do
 414                   {
 415                     /* Match the leading 0 or 0[xX] base indicator.  */
 416                     unsigned int base = 10;
 417                     if (*p == '0' && p[1] != '.')
 418                       {
 419                         base = 8;
 420                         ++p;
 421                         if (*p == 'x' || *p == 'X')
 422                           {
 423                             base = 16;
 424                             ++p;
 425                             if (*p == '.')
 426                               break; /* No digit here.  Give up on alias.  */
 427                           }
 428                         if (*p == '\0')
 429                           break;
 430                       }
 431
 432                     uint32_t part = 0; /* Accumulates this part's number.  */
 433                     do
 434                       {
 435                         if (isdigit (*p) && (*p - '0' < base))
 436                           part = (part * base) + (*p - '0');
 437                         else if (base == 16 && isxdigit (*p))
 438                           part = (part << 4) + 10 + (tolower (*p) - 'a');
 439                         ++p;
 440                       } while (*p != '\0' && *p != '.');
 441
 442                     if (*p != '.')
 443                       break;    /* Bad form.  Give up on this name.  */
 444
 445                     /* Install this as the next more significant byte.  */
 446                     val |= part << shift;
 447                     shift += 8;
 448                     ++p;
 449
 450                     /* If we are out of digits now, there are two cases:
 451                        1. We are done with digits and now see "in-addr.arpa".
 452                        2. This is not the droid we are looking for.  */
 453                     if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
 454                       {
 455                         result->n_net = val;
 456                         return NSS_STATUS_SUCCESS;
 457                       }
 458
 459                     /* Keep going when we have seen fewer than 4 parts.  */
 460                   } while (shift < 32);
 461               }
 462           }
 463           break;
 464         }
 465     }
 466
 467   __set_h_errno (TRY_AGAIN);
 468   return NSS_STATUS_TRYAGAIN;
 469 }