src/dnsserver.cc

   1
   2 /*
   3  * $Id: dnsserver.cc,v 1.74 2008/02/26 21:49:34 amosjeffries Exp $
   4  *
   5  * DEBUG: section 0     DNS Resolver
   6  * AUTHOR: Harvest Derived
   7  *
   8  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   9  * ----------------------------------------------------------
  10  *
  11  *  Squid is the result of efforts by numerous individuals from
  12  *  the Internet community; see the CONTRIBUTORS file for full
  13  *  details.   Many organizations have provided support for Squid's
  14  *  development; see the SPONSORS file for full details.  Squid is
  15  *  Copyrighted (C) 2001 by the Regents of the University of
  16  *  California; see the COPYRIGHT file for full details.  Squid
  17  *  incorporates software developed and/or copyrighted by other
  18  *  sources; see the CREDITS file for full details.
  19  *
  20  *  This program is free software; you can redistribute it and/or modify
  21  *  it under the terms of the GNU General Public License as published by
  22  *  the Free Software Foundation; either version 2 of the License, or
  23  *  (at your option) any later version.
  24  *
  25  *  This program is distributed in the hope that it will be useful,
  26  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  *  GNU General Public License for more details.
  29  *
  30  *  You should have received a copy of the GNU General Public License
  31  *  along with this program; if not, write to the Free Software
  32  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  33  *
  34  */
  35
  36 #include "config.h"
  37
  38 #if HAVE_UNISTD_H
  39 #include <unistd.h>
  40 #endif
  41 #if HAVE_STDLIB_H
  42 #include <stdlib.h>
  43 #endif
  44 #if HAVE_STDIO_H
  45 #include <stdio.h>
  46 #endif
  47 #if HAVE_SYS_TYPES_H
  48 #include <sys/types.h>
  49 #endif
  50 #if HAVE_CTYPE_H
  51 #include <ctype.h>
  52 #endif
  53 #if HAVE_ERRNO_H
  54 #include <errno.h>
  55 #endif
  56 #if HAVE_FCNTL_H
  57 #include <fcntl.h>
  58 #endif
  59 #if HAVE_GRP_H
  60 #include <grp.h>
  61 #endif
  62 #if HAVE_GNUMALLOC_H
  63 #include <gnumalloc.h>
  64 #elif HAVE_MALLOC_H
  65 #include <malloc.h>
  66 #endif
  67 #if HAVE_MEMORY_H
  68 #include <memory.h>
  69 #endif
  70 #if HAVE_NETDB_H && !defined(_SQUID_NETDB_H_)   /* protect NEXTSTEP */
  71 #define _SQUID_NETDB_H_
  72 #include <netdb.h>
  73 #endif
  74 #if HAVE_PWD_H
  75 #include <pwd.h>
  76 #endif
  77 #if HAVE_SIGNAL_H
  78 #include <signal.h>
  79 #endif
  80 #if HAVE_TIME_H
  81 #include <time.h>
  82 #endif
  83 #if HAVE_SYS_PARAM_H
  84 #include <sys/param.h>
  85 #endif
  86 #if HAVE_SYS_TIME_H
  87 #include <sys/time.h>
  88 #endif
  89 #if HAVE_SYS_RESOURCE_H
  90 #include <sys/resource.h>       /* needs sys/time.h above it */
  91 #endif
  92 #if HAVE_SYS_SOCKET_H
  93 #include <sys/socket.h>
  94 #endif
  95 #if HAVE_NETINET_IN_H
  96 #include <netinet/in.h>
  97 #endif
  98 #if HAVE_ARPA_INET_H
  99 #include <arpa/inet.h>
 100 #endif
 101 #if HAVE_SYS_STAT_H
 102 #include <sys/stat.h>
 103 #endif
 104 #if HAVE_SYS_UN_H
 105 #include <sys/un.h>
 106 #endif
 107 #if HAVE_SYS_WAIT_H
 108 #include <sys/wait.h>
 109 #endif
 110 #if HAVE_LIBC_H
 111 #include <libc.h>
 112 #endif
 113 #ifdef HAVE_SYS_SYSCALL_H
 114 #include <sys/syscall.h>
 115 #endif
 116 #ifdef HAVE_STRING_H
 117 #include <string.h>
 118 #endif
 119 #ifdef HAVE_STRINGS_H
 120 #include <strings.h>
 121 #endif
 122 #if HAVE_BSTRING_H
 123 #include <bstring.h>
 124 #endif
 125 #ifdef HAVE_CRYPT_H
 126 #include <crypt.h>
 127 #endif
 128 #if HAVE_SYS_SELECT_H
 129 #include <sys/select.h>
 130 #endif
 131 #if HAVE_GETOPT_H
 132 #include <getopt.h>
 133 #endif
 134
 135 #if HAVE_ARPA_NAMESER_H
 136 #include <arpa/nameser.h>
 137 #endif
 138 #if HAVE_RESOLV_H
 139 #include <resolv.h>
 140 #endif
 141
 142 #include "util.h"
 143
 144 /**
 145  \defgroup dnsserver dnsserver
 146  \ingroup ExternalPrograms
 147  \par
 148     Because the standard gethostbyname() library call
 149     blocks, Squid must use external processes to actually make
 150     these calls.  Typically there will be ten dnsserver
 151     processes spawned from Squid.  Communication occurs via
 152     TCP sockets bound to the loopback interface.  The functions
 153     in dns.cc are primarily concerned with starting and
 154     stopping the dnsservers.  Reading and writing to and from
 155     the dnsservers occurs in the \link IPCacheAPI IP\endlink and
 156     \link FQDNCacheAPI FQDN\endlink cache modules.
 157
 158  \section dnsserverInterface Command Line Interface
 159  \verbatim
 160 usage: dnsserver -Dhv -s nameserver
 161         -D             Enable resolver RES_DEFNAMES and RES_DNSRCH options
 162         -h             Help
 163         -v             Version
 164         -s nameserver  Specify alternate name server(s).  'nameserver'
 165                        must be an IP address, -s option may be repeated
 166  \endverbatim
 167  */
 168
 169 #include "IPAddress.h"
 170
 171 #if LIBRESOLV_DNS_TTL_HACK
 172 /// \ingroup dnsserver
 173 extern int _dns_ttl_;           /* this is a really *dirty* hack - bne */
 174 #endif
 175
 176 /*
 177  * res_init() is a macro re-definition of __res_init on: Debian
 178  */
 179 #if !defined(HAVE_RES_INIT) && defined(HAVE___RES_INIT)
 180 #ifndef res_init
 181 #define res_init  __res_init
 182 #endif
 183 #define HAVE_RES_INIT   HAVE___RES_INIT
 184 #endif
 185
 186 /// \ingroup dnsserver
 187 #define REQ_SZ 512
 188
 189 /**
 190  \ingroup dnsserver
 191  */
 192 static void
 193 lookup(const char *buf)
 194 {
 195     int ttl = 0;
 196     int retry = 0;
 197     unsigned int i = 0;
 198     IPAddress ipa;
 199     char ntoabuf[MAX_IPSTRLEN];
 200     struct addrinfo hints;
 201     struct addrinfo *AI = NULL;
 202     struct addrinfo *aiptr = NULL;
 203     struct addrinfo *prev_addr = NULL;
 204     int res = 0;
 205
 206     if (0 == strcmp(buf, "$shutdown"))
 207         exit(0);
 208
 209     if (0 == strcmp(buf, "$hello")) {
 210         printf("$alive\n");
 211         return;
 212     }
 213
 214     /* setup 'hints' for the system lookup */
 215     memset(&hints, '\0', sizeof(struct addrinfo));
 216     hints.ai_family = AF_UNSPEC;
 217     hints.ai_flags = AI_CANONNAME;
 218
 219     for (;;) {
 220         xfreeaddrinfo(AI);
 221         AI = NULL;
 222
 223         if( 0 == (res = xgetaddrinfo(buf,NULL,&hints,&AI)) )
 224             break;
 225
 226         if (res != EAI_AGAIN)
 227             break;
 228
 229         if (++retry == 3)
 230             break;
 231
 232         sleep(1);
 233     }
 234
 235     /* check if it's already an IP address in text form. */
 236     ipa = buf;
 237     if( ipa.IsAnyAddr() ) {
 238         /* its a domain name. Use the forward-DNS lookup already done */
 239
 240         if(res == 0) {
 241 #if LIBRESOLV_DNS_TTL_HACK
 242             /* DNS TTL handling - bne@CareNet.hu
 243              * for first try it's a dirty hack, by hacking getanswer
 244              * to place the ttl in a global variable */
 245             if (_dns_ttl_ > -1)
 246                 ttl = _dns_ttl_;
 247 #endif
 248             printf("$addr %d", ttl);
 249
 250             i = 0;
 251             aiptr = AI;
 252             while(NULL != aiptr && 32 >= i) {
 253                 memset(ntoabuf, 0, MAX_IPSTRLEN);
 254
 255                 /* getaddrinfo given a host has a nasty tendency to return duplicate addr's */
 256                 /* BUT sorted fortunately, so we can drop most of them easily */
 257                 if( prev_addr &&
 258                    prev_addr->ai_family==aiptr->ai_family &&
 259                    memcmp(aiptr->ai_addr, prev_addr->ai_addr, aiptr->ai_addrlen)==0
 260                   ) {
 261                     prev_addr = aiptr;
 262                     aiptr = aiptr->ai_next;
 263                     continue;
 264                 }
 265                 else {
 266                     prev_addr = aiptr;
 267                 }
 268
 269                 /* annoying inet_ntop breaks the nice code by requiring the in*_addr */
 270                 switch(aiptr->ai_family) {
 271                 case AF_INET:
 272                     xinet_ntop(aiptr->ai_family, &((struct sockaddr_in*)aiptr->ai_addr)->sin_addr, ntoabuf, MAX_IPSTRLEN);
 273                     break;
 274 #if USE_IPV6
 275                 case AF_INET6:
 276                     xinet_ntop(aiptr->ai_family, &((struct sockaddr_in6*)aiptr->ai_addr)->sin6_addr, ntoabuf, MAX_IPSTRLEN);
 277                     break;
 278 #endif
 279                 default:
 280                     aiptr = aiptr->ai_next;
 281                     continue;
 282                 }
 283                 printf(" %s", ntoabuf);
 284                 i++;
 285                 aiptr = aiptr->ai_next;
 286             }
 287
 288             prev_addr=NULL;
 289             printf("\n");
 290         }
 291     }
 292     else /* its an IPA in text form. perform rDNS */
 293     {
 294         /* You'd expect getaddrinfo given AI_CANONNAME would do a lookup on
 295          * missing FQDN. But no, it only copies the input string to that
 296          * position regardless of its content.
 297          */
 298         if(NULL != AI && NULL != AI->ai_addr) {
 299             for(;;) {
 300                 if( 0 == (res = xgetnameinfo(AI->ai_addr, AI->ai_addrlen, ntoabuf, MAX_IPSTRLEN, NULL,0,0)) )
 301                     break;
 302
 303                 if (res != EAI_AGAIN)
 304                     break;
 305
 306                 if (++retry == 3)
 307                     break;
 308
 309                 sleep(1);
 310             }
 311         }
 312
 313         if(res == 0) {
 314 #if LIBRESOLV_DNS_TTL_HACK
 315             /* DNS TTL handling - bne@CareNet.hu
 316              * for first try it's a dirty hack, by hacking getanswer
 317              * to place the ttl in a global variable */
 318             if (_dns_ttl_ > -1)
 319                 ttl = _dns_ttl_;
 320 #endif
 321
 322             printf("$name %d %s\n", ttl, ntoabuf);
 323         }
 324     }
 325
 326     switch(res) {
 327         case 0:
 328             /* no error. */
 329             break;
 330
 331         case EAI_AGAIN:
 332             printf("$fail Name Server for domain '%s' is unavailable.\n", buf);
 333             break;
 334
 335         case EAI_FAIL:
 336             printf("$fail DNS Domain/IP '%s' does not exist: %s.\n", buf, xgai_strerror(res));
 337             break;
 338
 339 #if defined(EAI_NODATA) || defined(EAI_NONAME)
 340 #ifdef EAI_NODATA
 341         /* deprecated. obsolete on some OS */
 342         case EAI_NODATA:
 343 #endif
 344 #ifdef EAI_NONAME
 345         case EAI_NONAME:
 346 #endif
 347             printf("$fail DNS Domain/IP '%s' exists without any FQDN/IPs: %s.\n", buf, xgai_strerror(res));
 348             break;
 349 #endif
 350        default:
 351             printf("$fail A system error occured looking up Domain/IP '%s': %s.\n", buf, xgai_strerror(res));
 352     }
 353
 354     xfreeaddrinfo(AI);
 355 }
 356
 357 /**
 358  \ingroup dnsserver
 359  */
 360 static void
 361 usage(void)
 362 {
 363     fprintf(stderr, "usage: dnsserver -hv -s nameserver\n"
 364             "\t-h             Help\n"
 365             "\t-v             Version\n"
 366             "\t-s nameserver  Specify alternate name server(s).  'nameserver'\n"
 367             "\t               must be an IPv4 address, -s option may be repeated\n"
 368             );
 369 }
 370
 371 #ifdef _SQUID_RES_NSADDR6_LARRAY
 372 /// \ingroup dnsserver
 373 #define _SQUID_RES_NSADDR6_LIST(i)      _SQUID_RES_NSADDR6_LARRAY[i].sin6_addr
 374 #endif
 375 #ifdef _SQUID_RES_NSADDR6_LPTR
 376 /// \ingroup dnsserver
 377 #define _SQUID_RES_NSADDR6_LIST(i)      _SQUID_RES_NSADDR6_LPTR[i]->sin6_addr
 378 #endif
 379
 380 /**
 381  \ingroup dnsserver
 382  *
 383  * This is the external dnsserver process.
 384  */
 385 int
 386 main(int argc, char *argv[])
 387 {
 388     char request[512];
 389     char *t = NULL;
 390     int c;
 391 #if defined(_SQUID_FREEBSD_) && defined(_SQUID_RES_NSADDR6_COUNT)
 392     /* Only seems to be valid on FreeBSD 5.5 where _res_ext was provided without an ns6addr counter! */
 393     /* Gone again on FreeBSD 6.2 along with _res_ext itself in any form. */
 394     int ns6count = 0;
 395 #endif
 396 #if HAVE_RES_INIT
 397
 398     IPAddress ipa;
 399     int opt_s = 0;
 400 #ifdef _SQUID_RES_NSADDR_LIST
 401
 402     extern char *optarg;
 403 #endif
 404 #endif
 405
 406 #if HAVE_RES_INIT
 407     res_init();
 408 #endif
 409
 410 #if USE_IPV6
 411     /* perform AAAA lookups *before* A lookups in IPv6 mode. */
 412     _res.options |= RES_USE_INET6;
 413 #endif
 414
 415     while ((c = getopt(argc, argv, "Dhs:v")) != -1) {
 416         switch (c) {
 417
 418         case 'D':
 419             fprintf(stderr, "-D is now default behaviour from this tool.\n");
 420             break;
 421
 422         case 's':
 423 #if HAVE_RES_INIT && (defined(_SQUID_RES_NSADDR_LIST) || defined(_SQUID_RES_NSADDR6_LIST))
 424
 425             if (opt_s == 0) {
 426 #if defined(_SQUID_RES_NSADDR_COUNT)
 427                 _SQUID_RES_NSADDR_COUNT = 0;
 428                 /* because I don't trust the nscount super-count entirely, make sure these are ALL invalid */
 429                 memset(_SQUID_RES_NSADDR_LIST, 0, sizeof(struct sockaddr_in)*MAXNS);
 430 #endif
 431 #if defined(_SQUID_RES_NSADDR6_COUNT)
 432                 _SQUID_RES_NSADDR6_COUNT = 0;
 433 #endif
 434                 opt_s = 1;
 435             }
 436
 437 /* AYJ:
 438  *  I experimented with all the permutations of mixed/unmixed nscount/nscount6 IPv4/IPv6/Both/invalid
 439  *
 440  *  I'm not sure if splitting them really helps.
 441  *  I've seen no evidence of IPv4 resolver *ever* being used when some IPv6 are set (or not even)
 442  *  BUT, have seen segfault when IPv4 is added to NSADDR6 list (_res._u._ext).
 443  *  It also appears to not do ANY lookup when _res.nscount==0.
 444  *
 445  *  BUT, even if _res.nsaddrs is memset to NULL, it resolves IFF IPv6 set in _ext.
 446  *
 447  *  SO, am splittig the IPv4/v6 into the seperate _res fields
 448  *      and making nscount a total of IPv4+IPv6 /w nscount6 the IPv6 sub-counter
 449  *      ie. nscount = count(NSv4)+count(NSv6) & nscount6 = count(NSv6)
 450  *
 451  * If ANYONE knows better please let us know.
 452  *
 453  */
 454             if( !(ipa = optarg) ) {
 455                 fprintf(stderr, "%s appears to be a bad nameserver FQDN/IP.\n",optarg);
 456             }
 457             else if( ipa.IsIPv4() ) {
 458                 if (_SQUID_RES_NSADDR_COUNT == MAXNS) {
 459                     fprintf(stderr, "Too many -s options, only %d are allowed\n", MAXNS);
 460                     break;
 461                 }
 462                 _SQUID_RES_NSADDR_LIST[_SQUID_RES_NSADDR_COUNT] = _SQUID_RES_NSADDR_LIST[0];
 463                 ipa.GetInAddr(_SQUID_RES_NSADDR_LIST[_SQUID_RES_NSADDR_COUNT++].sin_addr);
 464             }
 465             else if( ipa.IsIPv6() ) {
 466 #if USE_IPV6 && defined(_SQUID_RES_NSADDR6_LIST)
 467
 468                 /* because things NEVER seem to resolve in tests without _res.nscount being a total. */
 469                 if (_SQUID_RES_NSADDR_COUNT == MAXNS) {
 470                     fprintf(stderr, "Too many -s options, only %d are allowed\n", MAXNS);
 471                     break;
 472                 }
 473                 _SQUID_RES_NSADDR_COUNT++;
 474
 475                 ipa.GetInAddr(_SQUID_RES_NSADDR6_LIST(_SQUID_RES_NSADDR6_COUNT++));
 476 #else
 477                 fprintf(stderr, "IPv6 nameservers not supported on this resolver\n");
 478 #endif
 479             }
 480
 481 #else /* !HAVE_RES_INIT || !defined(_SQUID_RES_NSADDR_LIST) */
 482
 483             fprintf(stderr, "-s is not supported on this resolver\n");
 484
 485 #endif /* HAVE_RES_INIT */
 486
 487             break;
 488
 489         case 'v':
 490             printf("dnsserver version %s\n", VERSION);
 491
 492             exit(0);
 493
 494             break;
 495
 496         case 'h':
 497
 498         default:
 499             usage();
 500
 501             exit(1);
 502
 503             break;
 504         }
 505     }
 506
 507 #ifdef _SQUID_MSWIN_
 508     {
 509         WSADATA wsaData;
 510
 511         WSAStartup(2, &wsaData);
 512     }
 513
 514     fflush(stderr);
 515 #endif
 516
 517     for (;;) {
 518         memset(request, '\0', REQ_SZ);
 519
 520         if (fgets(request, REQ_SZ, stdin) == NULL) {
 521 #ifdef _SQUID_MSWIN_
 522             WSACleanup();
 523 #endif
 524             exit(1);
 525         }
 526
 527         t = strrchr(request, '\n');
 528
 529         if (t == NULL)          /* Ignore if no newline */
 530             continue;
 531
 532         *t = '\0';              /* strip NL */
 533
 534         if ((t = strrchr(request, '\r')) != NULL)
 535             *t = '\0';          /* strip CR */
 536
 537         lookup(request);
 538
 539         fflush(stdout);
 540     }
 541
 542     /* NOTREACHED */
 543     return 0;
 544 }