src/ngircd/resolve.c

   1 /*
   2  * ngIRCd -- The Next Generation IRC Daemon
   3  * Copyright (c)2001-2003 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 static char UNUSED id[] = "$Id: resolve.c,v 1.29 2008/02/26 22:04:17 fw Exp $";
  18
  19 #include "imp.h"
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <sys/socket.h>
  26 #include <netinet/in.h>
  27 #include <netdb.h>
  28
  29 #ifdef IDENTAUTH
  30 #ifdef HAVE_IDENT_H
  31 #include <ident.h>
  32 #endif
  33 #endif
  34
  35 #include "conn.h"
  36 #include "defines.h"
  37 #include "log.h"
  38
  39 #include "exp.h"
  40 #include "resolve.h"
  41 #include "io.h"
  42
  43
  44 static void Do_ResolveAddr PARAMS(( const ng_ipaddr_t *Addr, int Sock, int w_fd ));
  45 static void Do_ResolveName PARAMS(( const char *Host, int w_fd ));
  46 static bool register_callback PARAMS((RES_STAT *s, void (*cbfunc)(int, short)));
  47
  48 #ifdef WANT_IPV6
  49 extern bool Conf_ConnectIPv4;
  50 extern bool Conf_ConnectIPv6;
  51 #endif
  52
  53 static pid_t
  54 Resolver_fork(int *pipefds)
  55 {
  56         pid_t pid;
  57
  58         if (pipe(pipefds) != 0) {
  59                 Log( LOG_ALERT, "Resolver: Can't create output pipe: %s!", strerror( errno ));
  60                 return -1;
  61         }
  62
  63         pid = fork();
  64         switch(pid) {
  65                 case -1:
  66                         Log( LOG_CRIT, "Resolver: Can't fork: %s!", strerror( errno ));
  67                         close(pipefds[0]);
  68                         close(pipefds[1]);
  69                         return -1;
  70                 case 0: /* child */
  71                         close(pipefds[0]);
  72                         Log_Init_Resolver( );
  73                         return 0;
  74         }
  75         /* parent */
  76         close(pipefds[1]);
  77         return pid;
  78 }
  79
  80
  81 /**
  82  * Resolve IP (asynchronous!).
  83  */
  84 GLOBAL bool
  85 Resolve_Addr(RES_STAT * s, const ng_ipaddr_t *Addr, int identsock,
  86              void (*cbfunc) (int, short))
  87 {
  88         int pipefd[2];
  89         pid_t pid;
  90
  91         assert(s != NULL);
  92
  93         pid = Resolver_fork(pipefd);
  94         if (pid > 0) {
  95                 Log(LOG_DEBUG, "Resolver for %s created (PID %d).", ng_ipaddr_tostr(Addr), pid);
  96
  97                 s->pid = pid;
  98                 s->resolver_fd = pipefd[0];
  99                 return register_callback(s, cbfunc);
 100         } else if( pid == 0 ) {
 101                 /* Sub process */
 102                 Do_ResolveAddr( Addr, identsock, pipefd[1]);
 103                 Log_Exit_Resolver( );
 104                 exit(0);
 105         }
 106         return false;
 107 } /* Resolve_Addr */
 108
 109
 110 /**
 111  * Resolve hostname (asynchronous!).
 112  */
 113 GLOBAL bool
 114 Resolve_Name( RES_STAT *s, const char *Host, void (*cbfunc)(int, short))
 115 {
 116         int pipefd[2];
 117         pid_t pid;
 118
 119         assert(s != NULL);
 120
 121         pid = Resolver_fork(pipefd);
 122         if (pid > 0) {
 123                 /* Main process */
 124 #ifdef DEBUG
 125                 Log( LOG_DEBUG, "Resolver for \"%s\" created (PID %d).", Host, pid );
 126 #endif
 127                 s->pid = pid;
 128                 s->resolver_fd = pipefd[0];
 129                 return register_callback(s, cbfunc);
 130         } else if( pid == 0 ) {
 131                 /* Sub process */
 132                 Do_ResolveName(Host, pipefd[1]);
 133                 Log_Exit_Resolver( );
 134                 exit(0);
 135         }
 136         return false;
 137 } /* Resolve_Name */
 138
 139
 140 GLOBAL void
 141 Resolve_Init(RES_STAT *s)
 142 {
 143         assert(s != NULL);
 144         s->resolver_fd = -1;
 145         s->pid = 0;
 146 }
 147
 148
 149 #ifndef WANT_IPV6
 150 #ifdef h_errno
 151 static char *
 152 Get_Error( int H_Error )
 153 {
 154         /* Get error message for H_Error */
 155         switch( H_Error ) {
 156         case HOST_NOT_FOUND:
 157                 return "host not found";
 158         case NO_DATA:
 159                 return "name valid but no IP address defined";
 160         case NO_RECOVERY:
 161                 return "name server error";
 162         case TRY_AGAIN:
 163                 return "name server temporary not available";
 164         }
 165         return "unknown error";
 166 }
 167 #endif /* h_errno */
 168 #endif /* WANT_IPV6 */
 169
 170
 171 /* Do "IDENT" (aka "AUTH") lookup and append result to resolved_addr array */
 172 static void
 173 Do_IdentQuery(int identsock, array *resolved_addr)
 174 {
 175 #ifdef IDENTAUTH
 176         char *res;
 177
 178         assert(identsock >= 0);
 179
 180 #ifdef DEBUG
 181         Log_Resolver(LOG_DEBUG, "Doing IDENT lookup on socket %d ...", identsock);
 182 #endif
 183         if (identsock < 0)
 184                 return;
 185         res = ident_id( identsock, 10 );
 186 #ifdef DEBUG
 187         Log_Resolver(LOG_DEBUG, "Ok, IDENT lookup on socket %d done: \"%s\"",
 188                                                 identsock, res ? res : "(NULL)" );
 189 #endif
 190         if (!res) /* no result */
 191                 return;
 192         if (!array_cats(resolved_addr, res))
 193                 Log_Resolver(LOG_WARNING, "Resolver: Cannot copy IDENT result: %s!", strerror(errno));
 194
 195         free(res);
 196 #else
 197         (void) identsock;
 198         (void) resolved_addr;
 199 #endif
 200 }
 201
 202
 203 /**
 204  * perform reverse DNS lookup and put result string into resbuf.
 205  * If no hostname could be obtained, this function stores the string representation of
 206  * the IP address in resbuf and returns false.
 207  * @param IpAddr ip address to resolve
 208  * @param resbuf result buffer to store DNS name/string representation of ip address
 209  * @reslen size of result buffer (must be >= NGT_INET_ADDRSTRLEN)
 210  * @return true if reverse lookup successful, false otherwise
 211  */
 212 static bool
 213 ReverseLookup(const ng_ipaddr_t *IpAddr, char *resbuf, size_t reslen)
 214 {
 215         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 216         const char *errmsg;
 217 #ifdef HAVE_GETNAMEINFO
 218         static const char funcname[]="getnameinfo";
 219         int res;
 220
 221         *resbuf = 0;
 222
 223         res = getnameinfo((struct sockaddr *) IpAddr, ng_ipaddr_salen(IpAddr),
 224                                 resbuf, reslen, NULL, 0, NI_NAMEREQD);
 225         if (res == 0)
 226                 return true;
 227
 228         if (res == EAI_SYSTEM)
 229                 errmsg = strerror(errno);
 230         else
 231                 errmsg = gai_strerror(res);
 232 #else
 233         const struct sockaddr_in *Addr = (const struct sockaddr_in *) IpAddr;
 234         struct hostent *h;
 235         static const char funcname[]="gethostbyaddr";
 236
 237         h = gethostbyaddr((char *)&Addr->sin_addr, sizeof(Addr->sin_addr), AF_INET);
 238         if (h) {
 239                 if (strlcpy(resbuf, h->h_name, reslen) < reslen)
 240                         return true;
 241                 errmsg = "hostname too long";
 242         } else {
 243 # ifdef h_errno
 244                 errmsg = Get_Error(h_errno);
 245 # else
 246                 errmsg = "unknown error";
 247 # endif /* h_errno */
 248         }
 249 #endif  /* HAVE_GETNAMEINFO */
 250
 251         assert(errmsg);
 252         assert(reslen >= NG_INET_ADDRSTRLEN);
 253         ng_ipaddr_tostr_r(IpAddr, tmp_ip_str);
 254
 255         Log_Resolver(LOG_WARNING, "%s: Can't resolve address \"%s\": %s",
 256                                 funcname, tmp_ip_str, errmsg);
 257         strlcpy(resbuf, tmp_ip_str, reslen);
 258         return false;
 259 }
 260
 261
 262 /**
 263  * perform DNS lookup of given host name and fill IpAddr with a list of
 264  * ip addresses associated with that name.
 265  * ip addresses found are stored in the "array *IpAddr" argument (type ng_ipaddr_t)
 266  * @param hostname The domain name to look up.
 267  * @param IpAddr pointer to empty and initialized array to store results
 268  * @return true if lookup successful, false if domain name not found
 269  */
 270 static bool
 271 ForwardLookup(const char *hostname, array *IpAddr)
 272 {
 273         ng_ipaddr_t addr;
 274
 275 #ifdef HAVE_GETADDRINFO
 276         int res;
 277         struct addrinfo *a, *ai_results;
 278         static struct addrinfo hints;
 279
 280 #ifndef WANT_IPV6
 281         hints.ai_family = AF_INET;
 282 #endif
 283 #ifdef AI_ADDRCONFIG    /* glibc has this, but not e.g. netbsd 4.0 */
 284         hints.ai_flags = AI_ADDRCONFIG;
 285 #endif
 286         hints.ai_socktype = SOCK_STREAM;
 287         hints.ai_protocol = IPPROTO_TCP;
 288
 289 #ifdef WANT_IPV6
 290         assert(Conf_ConnectIPv6 || Conf_ConnectIPv4);
 291
 292         if (!Conf_ConnectIPv6)
 293                 hints.ai_family = AF_INET;
 294         if (!Conf_ConnectIPv4)
 295                 hints.ai_family = AF_INET6;
 296 #endif
 297         res = getaddrinfo(hostname, NULL, &hints, &ai_results);
 298         switch (res) {
 299         case 0: break;
 300         case EAI_SYSTEM:
 301                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, strerror(errno));
 302                 return false;
 303         default:
 304                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, gai_strerror(res));
 305                 return false;
 306         }
 307
 308         for (a = ai_results; a != NULL; a = a->ai_next) {
 309                 assert(a->ai_addrlen <= sizeof(addr));
 310
 311                 if (a->ai_addrlen > sizeof(addr))
 312                         continue;
 313
 314                 memcpy(&addr, a->ai_addr, a->ai_addrlen);
 315
 316                 if (!array_catb(IpAddr, (char *)&addr, sizeof(addr)))
 317                         break;
 318         }
 319
 320         freeaddrinfo(ai_results);
 321         return a == NULL;
 322 #else
 323         struct hostent *h = gethostbyname(hostname);
 324
 325         if (!h) {
 326 #ifdef h_errno
 327                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\": %s", hostname, Get_Error(h_errno));
 328 #else
 329                 Log_Resolver(LOG_WARNING, "Can't resolve \"%s\"", hostname);
 330 #endif
 331                 return false;
 332         }
 333         memset(&addr, 0, sizeof(addr));
 334
 335         addr.sin4.sin_family = AF_INET;
 336         memcpy(&addr.sin4.sin_addr, h->h_addr, sizeof(struct in_addr));
 337
 338         return array_copyb(IpAddr, (char *)&addr, sizeof(addr));
 339 #endif /* HAVE_GETADDRINFO */
 340 }
 341
 342
 343 static bool
 344 Addr_in_list(const array *resolved_addr, const ng_ipaddr_t *Addr)
 345 {
 346         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 347         const ng_ipaddr_t *tmpAddrs = array_start(resolved_addr);
 348         size_t len = array_length(resolved_addr, sizeof(*tmpAddrs));
 349
 350         assert(len > 0);
 351         assert(tmpAddrs);
 352
 353         while (len > 0) {
 354                 if (ng_ipaddr_ipequal(Addr, tmpAddrs))
 355                         return true;
 356                 tmpAddrs++;
 357                 len--;
 358         }
 359         /* failed; print list of addresses */
 360         ng_ipaddr_tostr_r(Addr, tmp_ip_str);
 361         len = array_length(resolved_addr, sizeof(*tmpAddrs));
 362         tmpAddrs = array_start(resolved_addr);
 363
 364         while (len > 0) {
 365                 Log_Resolver(LOG_WARNING, "Address mismatch: %s != %s",
 366                         tmp_ip_str, ng_ipaddr_tostr(tmpAddrs));
 367                 tmpAddrs++;
 368                 len--;
 369         }
 370
 371         return false;
 372 }
 373
 374
 375 static void
 376 Log_Forgery_NoIP(const char *ip, const char *host)
 377 {
 378         Log_Resolver(LOG_WARNING, "Possible forgery: %s resolved to %s "
 379                 "(which has no ip address)", ip, host);
 380 }
 381
 382 static void
 383 Log_Forgery_WrongIP(const char *ip, const char *host)
 384 {
 385         Log_Resolver(LOG_WARNING,"Possible forgery: %s resolved to %s "
 386                 "(which points to different address)", ip, host);
 387 }
 388
 389
 390 static void
 391 ArrayWrite(int fd, const array *a)
 392 {
 393         size_t len = array_bytes(a);
 394         const char *data = array_start(a);
 395
 396         assert(data);
 397
 398         if( (size_t)write(fd, data, len) != len )
 399                 Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!",
 400                                                         strerror(errno));
 401 }
 402
 403
 404 static void
 405 Do_ResolveAddr(const ng_ipaddr_t *Addr, int identsock, int w_fd)
 406 {
 407         /* Resolver sub-process: resolve IP address and write result into
 408          * pipe to parent. */
 409         char hostname[CLIENT_HOST_LEN];
 410         char tmp_ip_str[NG_INET_ADDRSTRLEN];
 411         size_t len;
 412         array resolved_addr;
 413
 414         array_init(&resolved_addr);
 415         ng_ipaddr_tostr_r(Addr, tmp_ip_str);
 416 #ifdef DEBUG
 417         Log_Resolver(LOG_DEBUG, "Now resolving %s ...", tmp_ip_str);
 418 #endif
 419         if (!ReverseLookup(Addr, hostname, sizeof(hostname)))
 420                 goto dns_done;
 421
 422         if (ForwardLookup(hostname, &resolved_addr)) {
 423                 if (!Addr_in_list(&resolved_addr, Addr)) {
 424                         Log_Forgery_WrongIP(tmp_ip_str, hostname);
 425                         strlcpy(hostname, tmp_ip_str, sizeof(hostname));
 426                 }
 427         } else {
 428                 Log_Forgery_NoIP(tmp_ip_str, hostname);
 429                 strlcpy(hostname, tmp_ip_str, sizeof(hostname));
 430         }
 431 #ifdef DEBUG
 432         Log_Resolver(LOG_DEBUG, "Ok, translated %s to \"%s\".", tmp_ip_str, hostname);
 433 #endif
 434  dns_done:
 435         len = strlen(hostname);
 436         hostname[len] = '\n';
 437         if (!array_copyb(&resolved_addr, hostname, ++len)) {
 438                 Log_Resolver(LOG_CRIT, "Resolver: Can't copy resolved name: %s!", strerror(errno));
 439                 array_free(&resolved_addr);
 440                 return;
 441         }
 442
 443         Do_IdentQuery(identsock, &resolved_addr);
 444
 445         ArrayWrite(w_fd, &resolved_addr);
 446
 447         array_free(&resolved_addr);
 448 } /* Do_ResolveAddr */
 449
 450
 451 static void
 452 Do_ResolveName( const char *Host, int w_fd )
 453 {
 454         /* Resolver sub-process: resolve name and write result into pipe
 455          * to parent. */
 456         array IpAddrs;
 457 #ifdef DEBUG
 458         ng_ipaddr_t *addr;
 459         size_t len;
 460 #endif
 461         Log_Resolver(LOG_DEBUG, "Now resolving \"%s\" ...", Host);
 462
 463         array_init(&IpAddrs);
 464         /* Resolve hostname */
 465         if (!ForwardLookup(Host, &IpAddrs)) {
 466                 close(w_fd);
 467                 return;
 468         }
 469 #ifdef DEBUG
 470         len = array_length(&IpAddrs, sizeof(*addr));
 471         assert(len > 0);
 472         addr = array_start(&IpAddrs);
 473         assert(addr);
 474         for (; len > 0; --len,addr++) {
 475                 Log_Resolver(LOG_DEBUG, "translated \"%s\" to %s.",
 476                                         Host, ng_ipaddr_tostr(addr));
 477         }
 478 #endif
 479         /* Write result into pipe to parent */
 480         ArrayWrite(w_fd, &IpAddrs);
 481
 482         array_free(&IpAddrs);
 483 } /* Do_ResolveName */
 484
 485
 486 static bool
 487 register_callback( RES_STAT *s, void (*cbfunc)(int, short))
 488 {
 489         assert(cbfunc != NULL);
 490         assert(s != NULL);
 491         assert(s->resolver_fd >= 0);
 492
 493         if (io_setnonblock(s->resolver_fd) &&
 494                 io_event_create(s->resolver_fd, IO_WANTREAD, cbfunc))
 495                         return true;
 496
 497         Log( LOG_CRIT, "Resolver: Could not register callback function: %s!", strerror(errno));
 498         close(s->resolver_fd);
 499         Resolve_Init(s);
 500         return false;
 501 }
 502
 503
 504 GLOBAL bool
 505 Resolve_Shutdown( RES_STAT *s)
 506 {
 507         bool ret = false;
 508
 509         assert(s != NULL);
 510         assert(s->resolver_fd >= 0);
 511
 512         if (s->resolver_fd >= 0)
 513                 ret = io_close(s->resolver_fd);
 514
 515         Resolve_Init(s);
 516         return ret;
 517 }
 518
 519
 520 /**
 521  * Read result of resolver sub-process from pipe
 522  */
 523 GLOBAL size_t
 524 Resolve_Read( RES_STAT *s, void* readbuf, size_t buflen)
 525 {
 526         ssize_t bytes_read;
 527
 528         assert(buflen > 0);
 529
 530         /* Read result from pipe */
 531         bytes_read = read(s->resolver_fd, readbuf, buflen);
 532         if (bytes_read < 0) {
 533                 if (errno == EAGAIN)
 534                         return 0;
 535
 536                 Log( LOG_CRIT, "Resolver: Can't read result: %s!", strerror(errno));
 537                 bytes_read = 0;
 538         }
 539 #ifdef DEBUG
 540         else if (bytes_read == 0)
 541                 Log( LOG_DEBUG, "Resolver: Can't read result: EOF");
 542 #endif
 543         Resolve_Shutdown(s);
 544         return (size_t)bytes_read;
 545 }
 546 /* -eof- */
 547