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 1.12 2005/05/28 10:46:50 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 
43 
44 #ifdef IDENTAUTH
45 LOCAL void Do_ResolveAddr PARAMS(( struct sockaddr_in *Addr, int Sock, int w_fd ));
46 #else
47 LOCAL void Do_ResolveAddr PARAMS(( struct sockaddr_in *Addr, int w_fd ));
48 #endif
49 
50 LOCAL void Do_ResolveName PARAMS(( char *Host, int w_fd ));
51 
52 #ifdef h_errno
53 LOCAL char *Get_Error PARAMS(( int H_Error ));
54 #endif
55 
56 LOCAL RES_STAT *New_Res_Stat PARAMS(( void ));
57 
58 
59 GLOBAL void
60 Resolve_Init( void )
61 {
62 	/* Initialize module */
63 
64 	FD_ZERO( &Resolver_FDs );
65 } /* Resolve_Init */
66 
67 
68 #ifdef IDENTAUTH
69 GLOBAL RES_STAT *
70 Resolve_Addr( struct sockaddr_in *Addr, int Sock )
71 #else
72 GLOBAL RES_STAT *
73 Resolve_Addr( struct sockaddr_in *Addr )
74 #endif
75 {
76 	/* Resolve IP (asynchronous!). On errors, e.g. if the child process
77 	 * can't be forked, this functions returns NULL. */
78 
79 	RES_STAT *s;
80 	int pid;
81 
82 	s = New_Res_Stat( );
83 	if( ! s ) return NULL;
84 
85 	/* For sub-process */
86 	pid = fork( );
87 	if( pid > 0 )
88 	{
89 		/* Main process */
90 		Log( LOG_DEBUG, "Resolver for %s created (PID %d).", inet_ntoa( Addr->sin_addr ), pid );
91 		FD_SET( s->pipe[0], &Resolver_FDs );
92 		if( s->pipe[0] > Conn_MaxFD ) Conn_MaxFD = s->pipe[0];
93 		s->pid = pid;
94 		return s;
95 	}
96 	else if( pid == 0 )
97 	{
98 		/* Sub process */
99 		Log_Init_Resolver( );
100 #ifdef IDENTAUTH
101 		Do_ResolveAddr( Addr, Sock, s->pipe[1] );
102 #else
103 		Do_ResolveAddr( Addr, s->pipe[1] );
104 #endif
105 		Log_Exit_Resolver( );
106 		exit( 0 );
107 	}
108 	else
109 	{
110 		/* Error! */
111 		free( s );
112 		Log( LOG_CRIT, "Resolver: Can't fork: %s!", strerror( errno ));
113 		return NULL;
114 	}
115 } /* Resolve_Addr */
116 
117 
118 GLOBAL RES_STAT *
119 Resolve_Name( char *Host )
120 {
121 	/* Resolve hostname (asynchronous!). On errors, e.g. if the child
122 	 * process can't be forked, this functions returns NULL. */
123 
124 	RES_STAT *s;
125 	int pid;
126 
127 	s = New_Res_Stat( );
128 	if( ! s ) return NULL;
129 
130 	/* Fork sub-process */
131 	pid = fork( );
132 	if( pid > 0 )
133 	{
134 		/* Main process */
135 		Log( LOG_DEBUG, "Resolver for \"%s\" created (PID %d).", Host, pid );
136 		FD_SET( s->pipe[0], &Resolver_FDs );
137 		if( s->pipe[0] > Conn_MaxFD ) Conn_MaxFD = s->pipe[0];
138 		s->pid = pid;
139 		return s;
140 	}
141 	else if( pid == 0 )
142 	{
143 		/* Sub process */
144 		Log_Init_Resolver( );
145 		Do_ResolveName( Host, s->pipe[1] );
146 		Log_Exit_Resolver( );
147 		exit( 0 );
148 	}
149 	else
150 	{
151 		/* Error! */
152 		free( s );
153 		Log( LOG_CRIT, "Resolver: Can't fork: %s!", strerror( errno ));
154 		return NULL;
155 	}
156 } /* Resolve_Name */
157 
158 
159 #ifdef IDENTAUTH
160 LOCAL void
161 Do_ResolveAddr( struct sockaddr_in *Addr, int Sock, int w_fd )
162 #else
163 LOCAL void
164 Do_ResolveAddr( struct sockaddr_in *Addr, int w_fd )
165 #endif
166 {
167 	/* Resolver sub-process: resolve IP address and write result into
168 	 * pipe to parent. */
169 
170 	char hostname[HOST_LEN];
171 	struct hostent *h;
172 	size_t len;
173 #ifdef IDENTAUTH
174 	char *res;
175 #endif
176 
177 	/* Resolve IP address */
178 	Log_Resolver( LOG_DEBUG, "Now resolving %s ...", inet_ntoa( Addr->sin_addr ));
179 	h = gethostbyaddr( (char *)&Addr->sin_addr, sizeof( Addr->sin_addr ), AF_INET );
180 	if( h ) strlcpy( hostname, h->h_name, sizeof( hostname ));
181 	else
182 	{
183 #ifdef h_errno
184 		Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\": %s!", inet_ntoa( Addr->sin_addr ), Get_Error( h_errno ));
185 #else
186 		Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\"!", inet_ntoa( Addr->sin_addr ));
187 #endif	
188 		strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname ));
189 	}
190 	Log_Resolver( LOG_DEBUG, "Ok, translated %s to \"%s\".", inet_ntoa( Addr->sin_addr ), hostname );
191 
192 	/* Write resolver result into pipe to parent */
193 	len = strlen( hostname ); 
194 	hostname[len] = '\n'; len++;
195 	if( (size_t)write( w_fd, hostname, len ) != (size_t)len )
196 	{
197 		Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!", strerror( errno ));
198 		close( w_fd );
199 		return;
200 	}
201 
202 #ifdef IDENTAUTH
203 	/* Do "IDENT" (aka "AUTH") lookup and write result to parent */
204 	Log_Resolver( LOG_DEBUG, "Doing IDENT lookup on socket %d ...", Sock );
205 	res = ident_id( Sock, 10 );
206 	Log_Resolver( LOG_DEBUG, "Ok, IDENT lookup on socket %d done: \"%s\"", Sock, res ? res : "" );
207 
208 	/* Write IDENT result into pipe to parent */
209 	if (res) {
210 		len = strlen(res);
211 		res[len] = '\n';
212 		len++;
213 	} else len = 1;
214 
215 	if( (size_t)write( w_fd, res ? res : "\n", len ) != (size_t)len )
216 	{
217 		Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent (IDENT): %s!", strerror( errno ));
218 		close( w_fd );
219 	}
220 	free( res );
221 #endif
222 } /* Do_ResolveAddr */
223 
224 
225 LOCAL void
226 Do_ResolveName( char *Host, int w_fd )
227 {
228 	/* Resolver sub-process: resolve name and write result into pipe
229 	 * to parent. */
230 
231 	char ip[16];
232 	struct hostent *h;
233 	struct in_addr *addr;
234 	int len;
235 
236 	Log_Resolver( LOG_DEBUG, "Now resolving \"%s\" ...", Host );
237 
238 	/* Resolve hostname */
239 	h = gethostbyname( Host );
240 	if( h )
241 	{
242 		addr = (struct in_addr *)h->h_addr;
243 		strlcpy( ip, inet_ntoa( *addr ), sizeof( ip ));
244 	}
245 	else
246 	{
247 #ifdef h_errno
248 		Log_Resolver( LOG_WARNING, "Can't resolve \"%s\": %s!", Host, Get_Error( h_errno ));
249 #else
250 		Log_Resolver( LOG_WARNING, "Can't resolve \"%s\"!", Host );
251 #endif
252 		ip[0] = '\0';
253 	}
254 	if( ip[0] ) Log_Resolver( LOG_DEBUG, "Ok, translated \"%s\" to %s.", Host, ip );
255 
256 	/* Write result into pipe to parent */
257 	len = strlen( ip );
258 	ip[len] = '\n'; len++;
259 	if( (size_t)write( w_fd, ip, len ) != (size_t)len )
260 	{
261 		Log_Resolver( LOG_CRIT, "Resolver: Can't write to parent: %s!", strerror( errno ));
262 		close( w_fd );
263 	}
264 } /* Do_ResolveName */
265 
266 
267 #ifdef h_errno
268 
269 LOCAL char *
270 Get_Error( int H_Error )
271 {
272 	/* Get error message for H_Error */
273 
274 	switch( H_Error )
275 	{
276 		case HOST_NOT_FOUND:
277 			return "host not found";
278 		case NO_DATA:
279 			return "name valid but no IP address defined";
280 		case NO_RECOVERY:
281 			return "name server error";
282 		case TRY_AGAIN:
283 			return "name server temporary not available";
284 		default:
285 			return "unknown error";
286 	}
287 } /* Get_Error */
288 
289 #endif
290 
291 
292 LOCAL RES_STAT *
293 New_Res_Stat( void )
294 {
295 	RES_STAT *s;
296 
297 	/* Allocate memory */
298 	s = (RES_STAT *)malloc( sizeof( RES_STAT ));
299 	if( ! s )
300 	{
301 		Log( LOG_EMERG, "Resolver: Can't allocate memory! [Resolve_Addr]" );
302 		return NULL;
303 	}
304 
305 	/* Initialize pipe for result */
306 	if( pipe( s->pipe ) != 0 )
307 	{
308 		free( s );
309 		Log( LOG_ALERT, "Resolver: Can't create output pipe: %s!", strerror( errno ));
310 		return NULL;
311 	}
312 
313 	s->stage = 0;
314 	s->bufpos = 0;
315 	s->pid = -1;
316 
317 	return s;
318 } /* New_Res_Stat */
319 
320 
321 /* -eof- */