2 Unix SMB/CIFS implementation.
4 Copyright (C) Andrew Tridgell 1997-1998
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 /***************************************************************************
24 Add a DNS result to the name cache.
25 ****************************************************************************/
27 static struct name_record
*add_dns_result(struct nmb_name
*question
, struct in_addr addr
)
29 int name_type
= question
->name_type
;
32 pull_ascii_nstring(qname
, sizeof(qname
), question
->name
);
35 /* add the fail to WINS cache of names. give it 1 hour in the cache */
36 DEBUG(3,("add_dns_result: Negative DNS answer for %s\n", qname
));
37 (void)add_name_to_subnet( wins_server_subnet
, qname
, name_type
,
38 NB_ACTIVE
, 60*60, DNSFAIL_NAME
, 1, &addr
);
42 /* add it to our WINS cache of names. give it 2 hours in the cache */
43 DEBUG(3,("add_dns_result: DNS gave answer for %s of %s\n", qname
, inet_ntoa(addr
)));
45 return( add_name_to_subnet( wins_server_subnet
, qname
, name_type
,
46 NB_ACTIVE
, 2*60*60, DNS_NAME
, 1, &addr
) );
51 static int fd_in
= -1, fd_out
= -1;
52 static pid_t child_pid
= -1;
55 /* this is the structure that is passed between the parent and child */
58 struct in_addr result
;
61 /* a queue of pending requests waiting to be sent to the DNS child */
62 static struct packet_struct
*dns_queue
;
64 /* the packet currently being processed by the dns child */
65 static struct packet_struct
*dns_current
;
68 /***************************************************************************
69 return the fd used to gather async dns replies. This is added to the select
71 ****************************************************************************/
78 /***************************************************************************
79 handle DNS queries arriving from the parent
80 ****************************************************************************/
81 static void asyncdns_process(void)
83 struct query_record r
;
89 if (read_data(fd_in
, (char *)&r
, sizeof(r
)) != sizeof(r
))
92 pull_ascii_nstring( qname
, sizeof(qname
), r
.name
.name
);
93 r
.result
.s_addr
= interpret_addr(qname
);
95 if (write_data(fd_out
, (char *)&r
, sizeof(r
)) != sizeof(r
))
102 /**************************************************************************** **
103 catch a sigterm (in the child process - the parent has a different handler
104 see nmbd.c for details).
105 We need a separate term handler here so we don't release any
106 names that our parent is going to release, or overwrite a
107 WINS db that our parent is going to write.
108 **************************************************************************** */
110 static void sig_term(int sig
)
115 /***************************************************************************
116 Called by the parent process when it receives a SIGTERM - also kills the
117 child so we don't get child async dns processes lying around, causing trouble.
118 ****************************************************************************/
120 void kill_async_dns_child(void)
123 kill(child_pid
, SIGTERM
);
128 /***************************************************************************
129 create a child process to handle DNS lookups
130 ****************************************************************************/
131 void start_async_dns(void)
137 if (pipe(fd1
) || pipe(fd2
)) {
138 DEBUG(0,("can't create asyncdns pipes\n"));
142 child_pid
= sys_fork();
149 DEBUG(0,("started asyncdns process %d\n", (int)child_pid
));
156 CatchSignal(SIGUSR2
, SIG_IGN
);
157 CatchSignal(SIGUSR1
, SIG_IGN
);
158 CatchSignal(SIGHUP
, SIG_IGN
);
159 CatchSignal(SIGTERM
, SIGNAL_CAST sig_term
);
165 /***************************************************************************
166 check if a particular name is already being queried
167 ****************************************************************************/
168 static BOOL
query_current(struct query_record
*r
)
170 return dns_current
&&
171 nmb_name_equal(&r
->name
,
172 &dns_current
->packet
.nmb
.question
.question_name
);
176 /***************************************************************************
177 write a query to the child process
178 ****************************************************************************/
179 static BOOL
write_child(struct packet_struct
*p
)
181 struct query_record r
;
183 r
.name
= p
->packet
.nmb
.question
.question_name
;
185 return write_data(fd_out
, (char *)&r
, sizeof(r
)) == sizeof(r
);
188 /***************************************************************************
190 ****************************************************************************/
191 void run_dns_queue(void)
193 struct query_record r
;
194 struct packet_struct
*p
, *p2
;
195 struct name_record
*namerec
;
201 /* Allow SIGTERM to kill us. */
202 BlockSignals(False
, SIGTERM
);
204 if (!process_exists_by_pid(child_pid
)) {
209 if ((size
=read_data(fd_in
, (char *)&r
, sizeof(r
))) != sizeof(r
)) {
211 DEBUG(0,("Incomplete DNS answer from child!\n"));
214 BlockSignals(True
, SIGTERM
);
218 BlockSignals(True
, SIGTERM
);
220 namerec
= add_dns_result(&r
.name
, r
.result
);
223 if (query_current(&r
)) {
224 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
227 send_wins_name_query_response(NAM_ERR
, dns_current
, NULL
);
229 send_wins_name_query_response(0,dns_current
,namerec
);
233 dns_current
->locked
= False
;
234 free_packet(dns_current
);
238 /* loop over the whole dns queue looking for entries that
239 match the result we just got */
240 for (p
= dns_queue
; p
;) {
241 struct nmb_packet
*nmb
= &p
->packet
.nmb
;
242 struct nmb_name
*question
= &nmb
->question
.question_name
;
244 if (nmb_name_equal(question
, &r
.name
)) {
245 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
248 send_wins_name_query_response(NAM_ERR
, p
, NULL
);
250 send_wins_name_query_response(0,p
,namerec
);
255 p
->prev
->next
= p
->next
;
259 p
->next
->prev
= p
->prev
;
269 dns_current
= dns_queue
;
270 dns_queue
= dns_queue
->next
;
272 dns_queue
->prev
= NULL
;
273 dns_current
->next
= NULL
;
275 if (!write_child(dns_current
)) {
276 DEBUG(3,("failed to send DNS query to child!\n"));
282 /***************************************************************************
284 ****************************************************************************/
286 BOOL
queue_dns_query(struct packet_struct
*p
,struct nmb_name
*question
,
287 struct name_record
**n
)
289 if (in_dns
|| fd_in
== -1)
293 if (!write_child(p
)) {
294 DEBUG(3,("failed to send DNS query to child!\n"));
308 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question
)));
315 /***************************************************************************
316 we use this when we can't do async DNS lookups
317 ****************************************************************************/
319 BOOL
queue_dns_query(struct packet_struct
*p
,struct nmb_name
*question
,
320 struct name_record
**n
)
322 struct in_addr dns_ip
;
325 pull_ascii_nstring(qname
, question
->name
);
327 DEBUG(3,("DNS search for %s - ", nmb_namestr(question
)));
329 /* Unblock TERM signal so we can be killed in DNS lookup. */
330 BlockSignals(False
, SIGTERM
);
332 dns_ip
.s_addr
= interpret_addr(qname
);
334 /* Re-block TERM signal. */
335 BlockSignals(True
, SIGTERM
);
337 *n
= add_dns_result(question
, dns_ip
);
339 send_wins_name_query_response(NAM_ERR
, p
, NULL
);
341 send_wins_name_query_response(0, p
, *n
);
345 /***************************************************************************
346 With sync dns there is no child to kill on SIGTERM.
347 ****************************************************************************/
349 void kill_async_dns_child(void)