src/ngircd/resolve.c

   1 /*
   2  * ngIRCd -- The Next Generation IRC Daemon
   3  * Copyright (c)2001-2009 by Alexander Barton (alex@barton.de)
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  * Please read the file COPYING, README and AUTHORS for more information.
  10  *
  11  * Asynchronous resolver
  12  */
  13
  14
  15 #include "portab.h"
  16
  17 #include "imp.h"
  18 #include <assert.h>
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <sys/socket.h>
  24 #include <netinet/in.h>
  25 #include <netdb.h>
  26
  27 #ifdef IDENTAUTH
  28 #ifdef HAVE_IDENT_H
  29 #include <ident.h>
  30 #endif
  31 #endif
  32
  33 #include "conn.h"
  34 #include "defines.h"
  35 #include "log.h"
  36
  37 #include "exp.h"
  38 #include "resolve.h"
  39 #include "io.h"
  40
  41
  42 static void Do_ResolveAddr PARAMS(( const ng_ipaddr_t *Addr, int Sock, int w_fd ));
  43 static void Do_ResolveName PARAMS(( const char *Host, int w_fd ));
  44 static bool register_callback PARAMS((RES_STAT *s, void (*cbfunc)(int, short)));
  45
  46 #ifdef WANT_IPV6
  47 extern bool Conf_ConnectIPv4;
  48 extern bool Conf_ConnectIPv6;
  49 #endif
  50
  51 static pid_t
  52 Resolver_fork(int *pipefds)
  53 {
  54         pid_t pid;
  55
  56         if (pipe(pipefds) != 0) {
  57                 Log( LOG_ALERT, "Resolver: Can't create output pipe: %s!", strerror( errno ));
  58                 return -1;
  59         }
  60
  61         pid = fork();
  62         switch(pid) {
  63                 case -1:
  64                         Log( LOG_CRIT, "Resolver: Can't fork: %s!", strerror( errno ));
  65                         close(pipefds[0]);
  66                         close(pipefds[1]);
  67                         return -1;
  68                 case 0: /* child */
  69                         close(pipefds[0]);
  70                         Log_Init_Resolver( );
  71                         return 0;
  72         }
  73         /* parent */
  74         close(pipefds[1]);
  75         return pid;
  76 }
  77
  78
  79 /**
  80  * Resolve IP (asynchronous!).
  81  */
  82 GLOBAL bool
  83 Resolve_Addr(RES_STAT * s, const ng_ipaddr_t *Addr, int identsock,
  84              void (*cbfunc) (int, short))
  85 {
  86         int pipefd[2];
  87         pid_t pid;
  88
  89         assert(s != NULL);
  90
  91         pid = Resolver_fork(pipefd);
  92         if (pid > 0) {
  93                 LogDebug("Resolver for %s created (PID %d).", ng_ipaddr_tostr(Addr), pid);
  94
  95                 s->pid = pid;
  96                 s->resolver_fd = pipefd[0];
  97                 return register_callback(s, cbfunc);
  98         } else if( pid == 0 ) {
  99                 /* Sub process */
 100                 Do_ResolveAddr( Addr, identsock, pipefd[1]);
 101                 Log_Exit_Resolver( );
 102                 exit(0);
 103         }
 104         return false;
 105 } /* Resolve_Addr */
 106
 107
 108 /**
 109  * Resolve hostname (asynchronous!).
 110  */
 111 GLOBAL bool
 112 Resolve_Name( RES_STAT *s, const char *Host, void (*cbfunc)(int, short))
 113 {
 114         int pipefd[2];
 115         pid_t pid;
 116
 117         assert(s != NULL);
 118
 119         pid = Resolver_fork(pipefd);
 120         if (pid > 0) {
 121                 /* Main process */
 122 #ifdef DEBUG
 123                 Log( LOG_DEBUG, "Resolver for \"%s\" created (PID %d).", Host, pid );
 124 #endif
 125                 s->pid = pid;
 126                 s->resolver_fd = pipefd[0];
 127                 return register_callback(s, cbfunc);
 128         } else if( pid == 0 ) {
 129                 /* Sub process */
 130                 Do_ResolveName(Host, pipefd[1]);
 131                 Log_Exit_Resolver( );
 132                 exit(0);
 133         }
 134         return false;
 135 } /* Resolve_Name */
 136
 137
 138 GLOBAL void
 139 Resolve_Init(RES_STAT *s)
 140 {
 141         assert(s != NULL);
 142         s->resolver_fd = -1;
 143         s->pid = 0;
 144 }
 145
 146
 147 #ifndef WANT_IPV6
 148 #ifdef h_errno
 149 static char *
 150 Get_Error( int H_Error )
 151 {
 152         /* Get error message for H_Error */
 153         switch( H_Error ) {
 154         case HOST_NOT_FOUND:
 155                 return "host not found";
 156         case NO_DATA:
 157                 return "name valid but no IP address defined";
 158         case NO_RECOVERY:
 159                 return "name server error";
 160         case TRY_AGAIN:
 161                 return "name server temporary not available";
 162         }
 163         return "unknown error";
 164 }
 165 #endif /* h_errno */
 166 #endif /* WANT_IPV6 */
 167
 168
 169 /* Do "IDENT" (aka "AUTH") lookup and append result to resolved_addr array */
 170 static void
 171 Do_IdentQuery(int identsock, array *resolved_addr)
 172 {
 173 #ifdef IDENTAUTH
 174         char *res;
 175
 176         if (identsock < 0)
 177                 return;
 178
 179 #ifdef DEBUG
 180         Log_Resolver(LOG_DEBUG, "Doing IDENT lookup on socket %d ...", identsock);
 181 #endif
 182         res = ident_id( identsock, 10 );
 183 #ifdef DEBUG
 184         Log_Resolver(LOG_DEBUG, "Ok, IDENT lookup on socket %d done: \"%s\"",
 185                                                 identsock, res ? res : "(NULL)" );
 186 #endif
 187         if (!res) /* no result */
 188                 return;
 189         if (!array_cats(resolved_addr, res))
 190                 Log_Resolver(LOG_WARNING, "Resolver: Cannot copy IDENT result: %s!", strerror(errno));
 191
 192         free(res);
 193 #else
 194         (void) identsock;
 195         (void) resolved_addr;
 196 #endif
 197 }
 198
 199
 200 /**
 201  * perform reverse DNS lookup and put result string into resbuf.
 202  * If no hostname could be obtained, this function stores the string representation of
 203  * the IP address in resbuf and returns false.
 204  * @param IpAddr ip address to resolve
 205  * @param resbuf result buffer to store DNS name/string representation of ip address
 206  * @reslen size of result buffer (must be >= NGT_INET_ADDRSTRLEN)
 207  * @return true if reverse lookup successful, false otherwise
 208  */
 209 static bool
 210 ReverseLookup(const ng_ipaddr_t *IpAddr, char *resbuf, size_t reslen)
 211 {
 212         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 213         const char *errmsg;
 214 #ifdef HAVE_GETNAMEINFO
 215         static const char funcname[]="getnameinfo";
 216         int res;
 217
 218         *resbuf = 0;
 219
 220         res = getnameinfo((struct sockaddr *) IpAddr, ng_ipaddr_salen(IpAddr),
 221                           resbuf, (socklen_t)reslen, NULL, 0, NI_NAMEREQD);
 222         if (res == 0)
 223                 return true;
 224
 225         if (res == EAI_SYSTEM)
 226                 errmsg = strerror(errno);
 227         else
 228                 errmsg = gai_strerror(res);
 229 #else
 230         const struct sockaddr_in *Addr = (const struct sockaddr_in *) IpAddr;
 231         struct hostent *h;
 232         static const char funcname[]="gethostbyaddr";
 233
 234         h = gethostbyaddr((char *)&Addr->sin_addr, sizeof(Addr->sin_addr), AF_INET);
 235         if (h) {
 236                 if (strlcpy(resbuf, h->h_name, reslen) < reslen)
 237                         return true;
 238                 errmsg = "hostname too long";
 239         } else {
 240 # ifdef h_errno
 241                 errmsg = Get_Error(h_errno);
 242 # else
 243                 errmsg = "unknown error";
 244 # endif /* h_errno */
 245         }
 246 #endif  /* HAVE_GETNAMEINFO */
 247
 248         assert(errmsg);
 249         assert(reslen >= NG_INET_ADDRSTRLEN);
 250         ng_ipaddr_tostr_r(IpAddr, tmp_ip_str);
 251
 252         Log_Resolver(LOG_WARNING, "%s: Can't resolve address \"%s\": %s",
 253                                 funcname, tmp_ip_str, errmsg);
 254         strlcpy(resbuf, tmp_ip_str, reslen);
 255         return false;
 256 }
 257
 258
 259 /**
 260  * perform DNS lookup of given host name and fill IpAddr with a list of
 261  * ip addresses associated with that name.
 262  * ip addresses found are stored in the "array *IpAddr" argument (type ng_ipaddr_t)
 263  * @param hostname The domain name to look up.
 264  * @param IpAddr pointer to empty and initialized array to store results
 265  * @return true if lookup successful, false if domain name not found
 266  */
 267 static bool
 268 ForwardLookup(const char *hostname, array *IpAddr)
 269 {
 270         ng_ipaddr_t addr;
 271
 272 #ifdef HAVE_GETADDRINFO
 273         int res;
 274         struct addrinfo *a, *ai_results;
 275         static struct addrinfo hints;
 276
 277 #ifndef WANT_IPV6
 278         hints.ai_family = AF_INET;
 279 #endif
 280 #ifdef AI_ADDRCONFIG    /* glibc has this, but not e.g. netbsd 4.0 */
 281         hints.ai_flags = AI_ADDRCONFIG;
 282 #endif
 283         hints.ai_socktype = SOCK_STREAM;
 284         hints.ai_protocol = IPPROTO_TCP;
 285
 286 #ifdef WANT_IPV6
 287         assert(Conf_ConnectIPv6 || Conf_ConnectIPv4);
 288
 289         if (!Conf_ConnectIPv6)
 290                 hints.ai_family = AF_INET;
 291         if (!Conf_ConnectIPv4)
 292                 hints.ai_family = AF_INET6;
 293 #endif
 294         memset(&addr, 0, sizeof(addr));
 295
 296         res = getaddrinfo(hostname, NULL, &hints, &ai_results);
 297         switch (res) {
 298         case 0: break;
 299         case EAI_SYSTEM:
 300                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, strerror(errno));
 301                 return false;
 302         default:
 303                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, gai_strerror(res));
 304                 return false;
 305         }
 306
 307         for (a = ai_results; a != NULL; a = a->ai_next) {
 308                 assert(a->ai_addrlen <= sizeof(addr));
 309
 310                 if (a->ai_addrlen > sizeof(addr))
 311                         continue;
 312
 313                 memcpy(&addr, a->ai_addr, a->ai_addrlen);
 314
 315                 if (!array_catb(IpAddr, (char *)&addr, sizeof(addr)))
 316                         break;
 317         }
 318
 319         freeaddrinfo(ai_results);
 320         return a == NULL;
 321 #else
 322         struct hostent *h = gethostbyname(hostname);
 323
 324         if (!h) {
 325 #ifdef h_errno
 326                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, Get_Error(h_errno));
 327 #else
 328                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\"", hostname);
 329 #endif
 330                 return false;
 331         }
 332         memset(&addr, 0, sizeof(addr));
 333
 334         addr.sin4.sin_family = AF_INET;
 335         memcpy(&addr.sin4.sin_addr, h->h_addr, sizeof(struct in_addr));
 336
 337         return array_copyb(IpAddr, (char *)&addr, sizeof(addr));
 338 #endif /* HAVE_GETADDRINFO */
 339 }
 340
 341
 342 static bool
 343 Addr_in_list(const array *resolved_addr, const ng_ipaddr_t *Addr)
 344 {
 345         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 346         const ng_ipaddr_t *tmpAddrs = array_start(resolved_addr);
 347         size_t len = array_length(resolved_addr, sizeof(*tmpAddrs));
 348
 349         assert(len > 0);
 350         assert(tmpAddrs);
 351
 352         while (len > 0) {
 353                 if (ng_ipaddr_ipequal(Addr, tmpAddrs))
 354                         return true;
 355                 tmpAddrs++;
 356                 len--;
 357         }
 358         /* failed; print list of addresses */
 359         ng_ipaddr_tostr_r(Addr, tmp_ip_str);
 360         len = array_length(resolved_addr, sizeof(*tmpAddrs));
 361         tmpAddrs = array_start(resolved_addr);
 362
 363         while (len > 0) {
 364                 Log_Resolver(LOG_WARNING, "Address mismatch: %s != %s",
 365                         tmp_ip_str, ng_ipaddr_tostr(tmpAddrs));
 366                 tmpAddrs++;
 367                 len--;
 368         }
 369
 370         return false;
 371 }
 372
 373
 374 static void
 375 Log_Forgery_NoIP(const char *ip, const char *host)
 376 {
 377         Log_Resolver(LOG_WARNING, "Possible forgery: %s resolved to %s "
 378                 "(which has no ip address)", ip, host);
 379 }
 380
 381 static void
 382 Log_Forgery_WrongIP(const char *ip, const char *host)
 383 {
 384         Log_Resolver(LOG_WARNING,"Possible forgery: %s resolved to %s "
 385                 "(which points to different address)", ip, host);
 386 }
 387
 388
 389 static void
 390 ArrayWrite(int fd, const array *a)
 391 {
 392         size_t len = array_bytes(a);
 393         const char *data = array_start(a);
 394
 395         assert(data);
 396
 397         if( (size_t)write(fd, data, len) != len )
 398                 Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!",
 399                                                         strerror(errno));
 400 }
 401
 402
 403 static void
 404 Do_ResolveAddr(const ng_ipaddr_t *Addr, int identsock, int w_fd)
 405 {
 406         /* Resolver sub-process: resolve IP address and write result into
 407          * pipe to parent. */
 408         char hostname[CLIENT_HOST_LEN];
 409         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 410         size_t len;
 411         array resolved_addr;
 412
 413         array_init(&resolved_addr);
 414         ng_ipaddr_tostr_r(Addr, tmp_ip_str);
 415 #ifdef DEBUG
 416         Log_Resolver(LOG_DEBUG, "Now resolving %s ...", tmp_ip_str);
 417 #endif
 418         if (!ReverseLookup(Addr, hostname, sizeof(hostname)))
 419                 goto dns_done;
 420
 421         if (ForwardLookup(hostname, &resolved_addr)) {
 422                 if (!Addr_in_list(&resolved_addr, Addr)) {
 423                         Log_Forgery_WrongIP(tmp_ip_str, hostname);
 424                         strlcpy(hostname, tmp_ip_str, sizeof(hostname));
 425                 }
 426         } else {
 427                 Log_Forgery_NoIP(tmp_ip_str, hostname);
 428                 strlcpy(hostname, tmp_ip_str, sizeof(hostname));
 429         }
 430 #ifdef DEBUG
 431         Log_Resolver(LOG_DEBUG, "Ok, translated %s to \"%s\".", tmp_ip_str, hostname);
 432 #endif
 433  dns_done:
 434         len = strlen(hostname);
 435         hostname[len] = '\n';
 436         if (!array_copyb(&resolved_addr, hostname, ++len)) {
 437                 Log_Resolver(LOG_CRIT, "Resolver: Can't copy resolved name: %s!", strerror(errno));
 438                 array_free(&resolved_addr);
 439                 return;
 440         }
 441
 442         Do_IdentQuery(identsock, &resolved_addr);
 443
 444         ArrayWrite(w_fd, &resolved_addr);
 445
 446         array_free(&resolved_addr);
 447 } /* Do_ResolveAddr */
 448
 449
 450 static void
 451 Do_ResolveName( const char *Host, int w_fd )
 452 {
 453         /* Resolver sub-process: resolve name and write result into pipe
 454          * to parent. */
 455         array IpAddrs;
 456 #ifdef DEBUG
 457         ng_ipaddr_t *addr;
 458         size_t len;
 459 #endif
 460         Log_Resolver(LOG_DEBUG, "Now resolving \"%s\" ...", Host);
 461
 462         array_init(&IpAddrs);
 463         /* Resolve hostname */
 464         if (!ForwardLookup(Host, &IpAddrs)) {
 465                 close(w_fd);
 466                 return;
 467         }
 468 #ifdef DEBUG
 469         len = array_length(&IpAddrs, sizeof(*addr));
 470         assert(len > 0);
 471         addr = array_start(&IpAddrs);
 472         assert(addr);
 473         for (; len > 0; --len,addr++) {
 474                 Log_Resolver(LOG_DEBUG, "translated \"%s\" to %s.",
 475                                         Host, ng_ipaddr_tostr(addr));
 476         }
 477 #endif
 478         /* Write result into pipe to parent */
 479         ArrayWrite(w_fd, &IpAddrs);
 480
 481         array_free(&IpAddrs);
 482 } /* Do_ResolveName */
 483
 484
 485 static bool
 486 register_callback( RES_STAT *s, void (*cbfunc)(int, short))
 487 {
 488         assert(cbfunc != NULL);
 489         assert(s != NULL);
 490         assert(s->resolver_fd >= 0);
 491
 492         if (io_setnonblock(s->resolver_fd) &&
 493                 io_event_create(s->resolver_fd, IO_WANTREAD, cbfunc))
 494                         return true;
 495
 496         Log( LOG_CRIT, "Resolver: Could not register callback function: %s!", strerror(errno));
 497         close(s->resolver_fd);
 498         Resolve_Init(s);
 499         return false;
 500 }
 501
 502
 503 GLOBAL bool
 504 Resolve_Shutdown( RES_STAT *s)
 505 {
 506         bool ret = false;
 507
 508         assert(s != NULL);
 509         assert(s->resolver_fd >= 0);
 510
 511         if (s->resolver_fd >= 0)
 512                 ret = io_close(s->resolver_fd);
 513
 514         Resolve_Init(s);
 515         return ret;
 516 }
 517
 518
 519 /**
 520  * Read result of resolver sub-process from pipe
 521  */
 522 GLOBAL size_t
 523 Resolve_Read( RES_STAT *s, void* readbuf, size_t buflen)
 524 {
 525         ssize_t bytes_read;
 526
 527         assert(buflen > 0);
 528
 529         /* Read result from pipe */
 530         bytes_read = read(s->resolver_fd, readbuf, buflen);
 531         if (bytes_read < 0) {
 532                 if (errno == EAGAIN)
 533                         return 0;
 534
 535                 Log( LOG_CRIT, "Resolver: Can't read result: %s!", strerror(errno));
 536                 bytes_read = 0;
 537         }
 538 #ifdef DEBUG
 539         else if (bytes_read == 0)
 540                 Log( LOG_DEBUG, "Resolver: Can't read result: EOF");
 541 #endif
 542         Resolve_Shutdown(s);
 543         return (size_t)bytes_read;
 544 }
 545
 546
 547 /* -eof- */