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 1.22 2006/02/08 15:20:21 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 <arpa/inet.h>
  28 #include <netdb.h>
  29
  30 #ifdef IDENTAUTH
  31 #ifdef HAVE_IDENT_H
  32 #include <ident.h>
  33 #endif
  34 #endif
  35
  36 #include "conn.h"
  37 #include "defines.h"
  38 #include "log.h"
  39
  40 #include "exp.h"
  41 #include "resolve.h"
  42 #include "io.h"
  43
  44
  45 static void Do_ResolveAddr PARAMS(( struct sockaddr_in *Addr, int Sock, int w_fd ));
  46 static void Do_ResolveName PARAMS(( const char *Host, int w_fd ));
  47 static bool register_callback PARAMS((RES_STAT *s, void (*cbfunc)(int, short)));
  48
  49 #ifdef h_errno
  50 static char *Get_Error PARAMS(( int H_Error ));
  51 #endif
  52
  53 static int
  54 Resolver_fork(int *pipefds)
  55 {
  56         int pid;
  57         if (pipe(pipefds) != 0) {
  58                 Log( LOG_ALERT, "Resolver: Can't create output pipe: %s!", strerror( errno ));
  59                 return -1;
  60         }
  61
  62         pid = fork();
  63         switch(pid) {
  64                 case -1:
  65                         Log( LOG_CRIT, "Resolver: Can't fork: %s!", strerror( errno ));
  66                         close(pipefds[0]);
  67                         close(pipefds[1]);
  68                         return -1;
  69                 case 0: /* child */
  70                         close(pipefds[0]);
  71                         Log_Init_Resolver( );
  72                         return 0;
  73         }
  74         /* parent */
  75         close(pipefds[1]);
  76         return pid;
  77 }
  78
  79
  80 GLOBAL bool
  81 Resolve_Addr( RES_STAT *s, struct sockaddr_in *Addr, int identsock, void (*cbfunc)(int, short))
  82 {
  83         /* Resolve IP (asynchronous!). */
  84         int pid, pipefd[2];
  85         assert(s != NULL);
  86         s->success = false;
  87
  88         pid = Resolver_fork(pipefd);
  89         if (pid > 0) {
  90 #ifdef DEBUG
  91                 Log( LOG_DEBUG, "Resolver for %s created (PID %d).", inet_ntoa( Addr->sin_addr ), pid );
  92 #endif
  93                 s->pid = pid;
  94                 s->resolver_fd = pipefd[0];
  95                 return register_callback(s, cbfunc);
  96         } else if( pid == 0 ) {
  97                 /* Sub process */
  98                 Do_ResolveAddr( Addr, identsock, pipefd[1]);
  99                 Log_Exit_Resolver( );
 100                 exit(0);
 101         }
 102         return false;
 103 } /* Resolve_Addr */
 104
 105
 106 GLOBAL bool
 107 Resolve_Name( RES_STAT *s, const char *Host, void (*cbfunc)(int, short))
 108 {
 109         /* Resolve hostname (asynchronous!). */
 110         int pid, pipefd[2];
 111         assert(s != NULL);
 112         s->success = false;
 113
 114         pid = Resolver_fork(pipefd);
 115         if (pid > 0) {
 116                 /* Main process */
 117 #ifdef DEBUG
 118                 Log( LOG_DEBUG, "Resolver for \"%s\" created (PID %d).", Host, pid );
 119 #endif
 120                 s->pid = pid;
 121                 s->resolver_fd = pipefd[0];
 122                 return register_callback(s, cbfunc);
 123         } else if( pid == 0 ) {
 124                 /* Sub process */
 125                 Do_ResolveName(Host, pipefd[1]);
 126                 Log_Exit_Resolver( );
 127                 exit(0);
 128         }
 129         return false;
 130 } /* Resolve_Name */
 131
 132
 133 GLOBAL void
 134 Resolve_Init(RES_STAT *s)
 135 {
 136         assert(s != NULL);
 137         s->resolver_fd = -1;
 138         s->pid = 0;
 139         /* s->success must not be changed -- it will be set by other Resolve_*() functions */
 140 }
 141
 142
 143 static void
 144 Do_ResolveAddr( struct sockaddr_in *Addr, int identsock, int w_fd )
 145 {
 146         /* Resolver sub-process: resolve IP address and write result into
 147          * pipe to parent. */
 148
 149         char hostname[HOST_LEN];
 150         char ipstr[HOST_LEN];
 151         struct hostent *h;
 152         size_t len;
 153         struct in_addr *addr;
 154         char *ntoaptr;
 155         array resolved_addr;
 156 #ifdef IDENTAUTH
 157         char *res;
 158 #endif
 159         array_init(&resolved_addr);
 160         /* Resolve IP address */
 161 #ifdef DEBUG
 162         Log_Resolver( LOG_DEBUG, "Now resolving %s ...", inet_ntoa( Addr->sin_addr ));
 163 #endif
 164         h = gethostbyaddr( (char *)&Addr->sin_addr, sizeof( Addr->sin_addr ), AF_INET );
 165         if (!h) {
 166 #ifdef h_errno
 167                 Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\": %s!", inet_ntoa( Addr->sin_addr ), Get_Error( h_errno ));
 168 #else
 169                 Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\"!", inet_ntoa( Addr->sin_addr ));
 170 #endif
 171                 strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname ));
 172         } else {
 173                 strlcpy( hostname, h->h_name, sizeof( hostname ));
 174
 175                 h = gethostbyname( hostname );
 176                 if ( h ) {
 177                         if (memcmp(h->h_addr, &Addr->sin_addr, sizeof (struct in_addr))) {
 178                                 addr = (struct in_addr*) h->h_addr;
 179                                 strlcpy(ipstr, inet_ntoa(*addr), sizeof ipstr);
 180                                 ntoaptr = inet_ntoa( Addr->sin_addr );
 181                                 Log(LOG_WARNING,"Possible forgery: %s resolved to %s (which is at ip %s!)",
 182                                                                                 ntoaptr, hostname, ipstr);
 183                                 strlcpy( hostname, ntoaptr, sizeof hostname);
 184                         }
 185                 } else {
 186                         ntoaptr = inet_ntoa( Addr->sin_addr );
 187                         Log(LOG_WARNING, "Possible forgery: %s resolved to %s (which has no ip address)",
 188                                                                                         ntoaptr, hostname);
 189                         strlcpy( hostname, ntoaptr, sizeof hostname);
 190                 }
 191         }
 192         Log_Resolver( LOG_DEBUG, "Ok, translated %s to \"%s\".", inet_ntoa( Addr->sin_addr ), hostname );
 193
 194         len = strlen( hostname );
 195         hostname[len] = '\n'; len++;
 196         if (!array_copyb(&resolved_addr, hostname, len )) {
 197                 Log_Resolver( LOG_CRIT, "Resolver: Can't copy resolved name: %s!", strerror( errno ));
 198                 close( w_fd );
 199                 return;
 200         }
 201
 202 #ifdef IDENTAUTH
 203         assert(identsock >= 0);
 204         if (identsock >= 0) {
 205                 /* Do "IDENT" (aka "AUTH") lookup and append result to resolved_addr array */
 206 #ifdef DEBUG
 207                 Log_Resolver( LOG_DEBUG, "Doing IDENT lookup on socket %d ...", identsock );
 208 #endif
 209                 res = ident_id( identsock, 10 );
 210 #ifdef DEBUG
 211                 Log_Resolver(LOG_DEBUG, "Ok, IDENT lookup on socket %d done: \"%s\"",
 212                                                         identsock, res ? res : "(NULL)" );
 213 #endif
 214                 if (res && !array_cats(&resolved_addr, res)) {
 215                         Log_Resolver(LOG_WARNING, "Resolver: Cannot copy IDENT result: %s!", strerror(errno));
 216                         /* omit ident and return hostname only */
 217                 }
 218
 219                 if (res) free(res);
 220         }
 221 #else
 222         (void)identsock;
 223 #endif
 224         len = array_bytes(&resolved_addr);
 225         if( (size_t)write( w_fd, array_start(&resolved_addr), len) != len )
 226                 Log_Resolver( LOG_CRIT, "Resolver: Can't write result to parent: %s!", strerror( errno ));
 227
 228         close(w_fd);
 229         array_free(&resolved_addr);
 230 } /* Do_ResolveAddr */
 231
 232
 233 static void
 234 Do_ResolveName( const char *Host, int w_fd )
 235 {
 236         /* Resolver sub-process: resolve name and write result into pipe
 237          * to parent. */
 238
 239         char ip[16];
 240         struct hostent *h;
 241         struct in_addr *addr;
 242         int len;
 243
 244         Log_Resolver( LOG_DEBUG, "Now resolving \"%s\" ...", Host );
 245
 246         /* Resolve hostname */
 247         h = gethostbyname( Host );
 248         if( h ) {
 249                 addr = (struct in_addr *)h->h_addr;
 250                 strlcpy( ip, inet_ntoa( *addr ), sizeof( ip ));
 251         } else {
 252 #ifdef h_errno
 253                 Log_Resolver( LOG_WARNING, "Can't resolve \"%s\": %s!", Host, Get_Error( h_errno ));
 254 #else
 255                 Log_Resolver( LOG_WARNING, "Can't resolve \"%s\"!", Host );
 256 #endif
 257                 close(w_fd);
 258                 return;
 259         }
 260 #ifdef DEBUG
 261         Log_Resolver( LOG_DEBUG, "Ok, translated \"%s\" to %s.", Host, ip );
 262 #endif
 263         /* Write result into pipe to parent */
 264         len = strlen( ip );
 265         if( write( w_fd, ip, len ) != len) {
 266                 Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!", strerror( errno ));
 267                 close( w_fd );
 268         }
 269 } /* Do_ResolveName */
 270
 271
 272 #ifdef h_errno
 273
 274 static char *
 275 Get_Error( int H_Error )
 276 {
 277         /* Get error message for H_Error */
 278
 279         switch( H_Error )
 280         {
 281                 case HOST_NOT_FOUND:
 282                         return "host not found";
 283                 case NO_DATA:
 284                         return "name valid but no IP address defined";
 285                 case NO_RECOVERY:
 286                         return "name server error";
 287                 case TRY_AGAIN:
 288                         return "name server temporary not available";
 289                 default:
 290                         return "unknown error";
 291         }
 292 } /* Get_Error */
 293
 294 #endif
 295
 296
 297 static bool
 298 register_callback( RES_STAT *s, void (*cbfunc)(int, short))
 299 {
 300         assert(cbfunc);
 301         assert(s != NULL);
 302         assert(s->resolver_fd >= 0);
 303
 304         if (io_setnonblock(s->resolver_fd) &&
 305                 io_event_create(s->resolver_fd, IO_WANTREAD, cbfunc))
 306                         return true;
 307
 308         Log( LOG_CRIT, "Resolver: Could not register callback function: %s!", strerror(errno));
 309         Resolve_Shutdown(s);
 310         return false;
 311 }
 312
 313
 314 GLOBAL bool
 315 Resolve_Shutdown( RES_STAT *s)
 316 {
 317         bool ret = false;
 318
 319         assert(s != NULL);
 320         assert(s->resolver_fd >= 0);
 321
 322         if (s->resolver_fd >= 0)
 323                 ret = io_close(s->resolver_fd);
 324
 325         Resolve_Init(s);
 326         return ret;
 327 }
 328
 329
 330 GLOBAL size_t
 331 Resolve_Read( RES_STAT *s, void* readbuf, size_t buflen)
 332 {
 333         /* Read result of resolver sub-process from pipe */
 334         int err, bytes_read;
 335         assert(buflen > 0);
 336
 337         /* Read result from pipe */
 338         errno = 0;
 339         bytes_read = read(s->resolver_fd, readbuf, buflen);
 340         if (bytes_read < 0) {
 341                 if (errno != EAGAIN) {
 342                         err = errno;
 343                         Log( LOG_CRIT, "Resolver: Can't read result: %s!", strerror(err));
 344                         Resolve_Shutdown(s);
 345                         errno = err;
 346                         return 0;
 347                 }
 348                 return 0;
 349         }
 350
 351         Resolve_Shutdown(s);
 352         if (bytes_read == 0) {  /* EOF: lookup failed */
 353 #ifdef DEBUG
 354                 Log( LOG_DEBUG, "Resolver: Can't read result: EOF");
 355 #endif
 356                 return 0;
 357         }
 358
 359         s->success = true;
 360         return bytes_read;
 361 }
 362 /* -eof- */
 363