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 1.23 2006/02/08 15:24:10 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
  87         pid = Resolver_fork(pipefd);
  88         if (pid > 0) {
  89 #ifdef DEBUG
  90                 Log( LOG_DEBUG, "Resolver for %s created (PID %d).", inet_ntoa( Addr->sin_addr ), pid );
  91 #endif
  92                 s->pid = pid;
  93                 s->resolver_fd = pipefd[0];
  94                 return register_callback(s, cbfunc);
  95         } else if( pid == 0 ) {
  96                 /* Sub process */
  97                 Do_ResolveAddr( Addr, identsock, pipefd[1]);
  98                 Log_Exit_Resolver( );
  99                 exit(0);
 100         }
 101         return false;
 102 } /* Resolve_Addr */
 103
 104
 105 GLOBAL bool
 106 Resolve_Name( RES_STAT *s, const char *Host, void (*cbfunc)(int, short))
 107 {
 108         /* Resolve hostname (asynchronous!). */
 109         int pid, pipefd[2];
 110         assert(s != NULL);
 111
 112         pid = Resolver_fork(pipefd);
 113         if (pid > 0) {
 114                 /* Main process */
 115 #ifdef DEBUG
 116                 Log( LOG_DEBUG, "Resolver for \"%s\" created (PID %d).", Host, pid );
 117 #endif
 118                 s->pid = pid;
 119                 s->resolver_fd = pipefd[0];
 120                 return register_callback(s, cbfunc);
 121         } else if( pid == 0 ) {
 122                 /* Sub process */
 123                 Do_ResolveName(Host, pipefd[1]);
 124                 Log_Exit_Resolver( );
 125                 exit(0);
 126         }
 127         return false;
 128 } /* Resolve_Name */
 129
 130
 131 GLOBAL void
 132 Resolve_Init(RES_STAT *s)
 133 {
 134         assert(s != NULL);
 135         s->resolver_fd = -1;
 136         s->pid = 0;
 137 }
 138
 139
 140 static void
 141 Do_ResolveAddr( struct sockaddr_in *Addr, int identsock, int w_fd )
 142 {
 143         /* Resolver sub-process: resolve IP address and write result into
 144          * pipe to parent. */
 145
 146         char hostname[HOST_LEN];
 147         char ipstr[HOST_LEN];
 148         struct hostent *h;
 149         size_t len;
 150         struct in_addr *addr;
 151         char *ntoaptr;
 152         array resolved_addr;
 153 #ifdef IDENTAUTH
 154         char *res;
 155 #endif
 156         array_init(&resolved_addr);
 157         /* Resolve IP address */
 158 #ifdef DEBUG
 159         Log_Resolver( LOG_DEBUG, "Now resolving %s ...", inet_ntoa( Addr->sin_addr ));
 160 #endif
 161         h = gethostbyaddr( (char *)&Addr->sin_addr, sizeof( Addr->sin_addr ), AF_INET );
 162         if (!h) {
 163 #ifdef h_errno
 164                 Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\": %s!", inet_ntoa( Addr->sin_addr ), Get_Error( h_errno ));
 165 #else
 166                 Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\"!", inet_ntoa( Addr->sin_addr ));
 167 #endif
 168                 strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname ));
 169         } else {
 170                 strlcpy( hostname, h->h_name, sizeof( hostname ));
 171
 172                 h = gethostbyname( hostname );
 173                 if ( h ) {
 174                         if (memcmp(h->h_addr, &Addr->sin_addr, sizeof (struct in_addr))) {
 175                                 addr = (struct in_addr*) h->h_addr;
 176                                 strlcpy(ipstr, inet_ntoa(*addr), sizeof ipstr);
 177                                 ntoaptr = inet_ntoa( Addr->sin_addr );
 178                                 Log(LOG_WARNING,"Possible forgery: %s resolved to %s (which is at ip %s!)",
 179                                                                                 ntoaptr, hostname, ipstr);
 180                                 strlcpy( hostname, ntoaptr, sizeof hostname);
 181                         }
 182                 } else {
 183                         ntoaptr = inet_ntoa( Addr->sin_addr );
 184                         Log(LOG_WARNING, "Possible forgery: %s resolved to %s (which has no ip address)",
 185                                                                                         ntoaptr, hostname);
 186                         strlcpy( hostname, ntoaptr, sizeof hostname);
 187                 }
 188         }
 189         Log_Resolver( LOG_DEBUG, "Ok, translated %s to \"%s\".", inet_ntoa( Addr->sin_addr ), hostname );
 190
 191         len = strlen( hostname );
 192         hostname[len] = '\n'; len++;
 193         if (!array_copyb(&resolved_addr, hostname, len )) {
 194                 Log_Resolver( LOG_CRIT, "Resolver: Can't copy resolved name: %s!", strerror( errno ));
 195                 close( w_fd );
 196                 return;
 197         }
 198
 199 #ifdef IDENTAUTH
 200         assert(identsock >= 0);
 201         if (identsock >= 0) {
 202                 /* Do "IDENT" (aka "AUTH") lookup and append result to resolved_addr array */
 203 #ifdef DEBUG
 204                 Log_Resolver( LOG_DEBUG, "Doing IDENT lookup on socket %d ...", identsock );
 205 #endif
 206                 res = ident_id( identsock, 10 );
 207 #ifdef DEBUG
 208                 Log_Resolver(LOG_DEBUG, "Ok, IDENT lookup on socket %d done: \"%s\"",
 209                                                         identsock, res ? res : "(NULL)" );
 210 #endif
 211                 if (res && !array_cats(&resolved_addr, res)) {
 212                         Log_Resolver(LOG_WARNING, "Resolver: Cannot copy IDENT result: %s!", strerror(errno));
 213                         /* omit ident and return hostname only */
 214                 }
 215
 216                 if (res) free(res);
 217         }
 218 #else
 219         (void)identsock;
 220 #endif
 221         len = array_bytes(&resolved_addr);
 222         if( (size_t)write( w_fd, array_start(&resolved_addr), len) != len )
 223                 Log_Resolver( LOG_CRIT, "Resolver: Can't write result to parent: %s!", strerror( errno ));
 224
 225         close(w_fd);
 226         array_free(&resolved_addr);
 227 } /* Do_ResolveAddr */
 228
 229
 230 static void
 231 Do_ResolveName( const char *Host, int w_fd )
 232 {
 233         /* Resolver sub-process: resolve name and write result into pipe
 234          * to parent. */
 235
 236         char ip[16];
 237         struct hostent *h;
 238         struct in_addr *addr;
 239         int len;
 240
 241         Log_Resolver( LOG_DEBUG, "Now resolving \"%s\" ...", Host );
 242
 243         /* Resolve hostname */
 244         h = gethostbyname( Host );
 245         if( h ) {
 246                 addr = (struct in_addr *)h->h_addr;
 247                 strlcpy( ip, inet_ntoa( *addr ), sizeof( ip ));
 248         } else {
 249 #ifdef h_errno
 250                 Log_Resolver( LOG_WARNING, "Can't resolve \"%s\": %s!", Host, Get_Error( h_errno ));
 251 #else
 252                 Log_Resolver( LOG_WARNING, "Can't resolve \"%s\"!", Host );
 253 #endif
 254                 close(w_fd);
 255                 return;
 256         }
 257 #ifdef DEBUG
 258         Log_Resolver( LOG_DEBUG, "Ok, translated \"%s\" to %s.", Host, ip );
 259 #endif
 260         /* Write result into pipe to parent */
 261         len = strlen( ip );
 262         if( write( w_fd, ip, len ) != len) {
 263                 Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!", strerror( errno ));
 264                 close( w_fd );
 265         }
 266 } /* Do_ResolveName */
 267
 268
 269 #ifdef h_errno
 270
 271 static char *
 272 Get_Error( int H_Error )
 273 {
 274         /* Get error message for H_Error */
 275
 276         switch( H_Error )
 277         {
 278                 case HOST_NOT_FOUND:
 279                         return "host not found";
 280                 case NO_DATA:
 281                         return "name valid but no IP address defined";
 282                 case NO_RECOVERY:
 283                         return "name server error";
 284                 case TRY_AGAIN:
 285                         return "name server temporary not available";
 286                 default:
 287                         return "unknown error";
 288         }
 289 } /* Get_Error */
 290
 291 #endif
 292
 293
 294 static bool
 295 register_callback( RES_STAT *s, void (*cbfunc)(int, short))
 296 {
 297         assert(cbfunc);
 298         assert(s != NULL);
 299         assert(s->resolver_fd >= 0);
 300
 301         if (io_setnonblock(s->resolver_fd) &&
 302                 io_event_create(s->resolver_fd, IO_WANTREAD, cbfunc))
 303                         return true;
 304
 305         Log( LOG_CRIT, "Resolver: Could not register callback function: %s!", strerror(errno));
 306         Resolve_Shutdown(s);
 307         return false;
 308 }
 309
 310
 311 GLOBAL bool
 312 Resolve_Shutdown( RES_STAT *s)
 313 {
 314         bool ret = false;
 315
 316         assert(s != NULL);
 317         assert(s->resolver_fd >= 0);
 318
 319         if (s->resolver_fd >= 0)
 320                 ret = io_close(s->resolver_fd);
 321
 322         Resolve_Init(s);
 323         return ret;
 324 }
 325
 326
 327 GLOBAL size_t
 328 Resolve_Read( RES_STAT *s, void* readbuf, size_t buflen)
 329 {
 330         /* Read result of resolver sub-process from pipe */
 331         int err, bytes_read;
 332         assert(buflen > 0);
 333
 334         /* Read result from pipe */
 335         errno = 0;
 336         bytes_read = read(s->resolver_fd, readbuf, buflen);
 337         if (bytes_read < 0) {
 338                 if (errno != EAGAIN) {
 339                         err = errno;
 340                         Log( LOG_CRIT, "Resolver: Can't read result: %s!", strerror(err));
 341                         Resolve_Shutdown(s);
 342                         errno = err;
 343                         return 0;
 344                 }
 345                 return 0;
 346         }
 347
 348         Resolve_Shutdown(s);
 349         if (bytes_read == 0) {  /* EOF: lookup failed */
 350 #ifdef DEBUG
 351                 Log( LOG_DEBUG, "Resolver: Can't read result: EOF");
 352 #endif
 353                 return 0;
 354         }
 355
 356         return bytes_read;
 357 }
 358 /* -eof- */
 359