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;
30 char *qname = question->name;
34 /* add the fail to WINS cache of names. give it 1 hour in the cache */
35 DEBUG(3,("add_dns_result: Negative DNS answer for %s\n", qname));
36 (void)add_name_to_subnet( wins_server_subnet, qname, name_type,
37 NB_ACTIVE, 60*60, DNSFAIL_NAME, 1, &addr );
41 /* add it to our WINS cache of names. give it 2 hours in the cache */
42 DEBUG(3,("add_dns_result: DNS gave answer for %s of %s\n", qname, inet_ntoa(addr)));
44 return( add_name_to_subnet( wins_server_subnet, qname, name_type,
45 NB_ACTIVE, 2*60*60, DNS_NAME, 1, &addr ) );
52 static int fd_in = -1, fd_out = -1;
53 static pid_t child_pid = -1;
56 /* this is the structure that is passed between the parent and child */
59 struct in_addr result;
62 /* a queue of pending requests waiting to be sent to the DNS child */
63 static struct packet_struct *dns_queue;
65 /* the packet currently being processed by the dns child */
66 static struct packet_struct *dns_current;
69 /***************************************************************************
70 return the fd used to gather async dns replies. This is added to the select
72 ****************************************************************************/
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 fstrcpy(qname, r.name.name);
94 r.result.s_addr = interpret_addr(qname);
96 if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r))
103 /**************************************************************************** **
104 catch a sigterm (in the child process - the parent has a different handler
105 see nmbd.c for details).
106 We need a separate term handler here so we don't release any
107 names that our parent is going to release, or overwrite a
108 WINS db that our parent is going to write.
109 **************************************************************************** */
111 static void sig_term(int sig)
116 /***************************************************************************
117 Called by the parent process when it receives a SIGTERM - also kills the
118 child so we don't get child async dns processes lying around, causing trouble.
119 ****************************************************************************/
121 void kill_async_dns_child(void)
124 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(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;
271 if (dns_queue) dns_queue->prev = NULL;
272 dns_current->next = NULL;
274 if (!write_child(dns_current)) {
275 DEBUG(3,("failed to send DNS query to child!\n"));
282 /***************************************************************************
284 ****************************************************************************/
285 BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question,
286 struct name_record **n)
288 if (in_dns || fd_in == -1)
292 if (!write_child(p)) {
293 DEBUG(3,("failed to send DNS query to child!\n"));
307 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
314 /***************************************************************************
315 we use this when we can't do async DNS lookups
316 ****************************************************************************/
317 BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question,
318 struct name_record **n)
320 char *qname = question->name;
321 struct in_addr dns_ip;
323 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
325 /* Unblock TERM signal so we can be killed in DNS lookup. */
326 BlockSignals(False, SIGTERM);
328 dns_ip.s_addr = interpret_addr(qname);
330 /* Re-block TERM signal. */
331 BlockSignals(True, SIGTERM);
333 *n = add_dns_result(question, dns_ip);
335 send_wins_name_query_response(NAM_ERR, p, NULL);
337 send_wins_name_query_response(0, p, *n);
341 /***************************************************************************
342 With sync dns there is no child to kill on SIGTERM.
343 ****************************************************************************/
344 void kill_async_dns_child(void)