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 3 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, see <http://www.gnu.org/licenses/>.
22 /***************************************************************************
23 Add a DNS result to the name cache.
24 ****************************************************************************/
26 static struct name_record *add_dns_result(struct nmb_name *question, struct in_addr addr)
28 int name_type = question->name_type;
31 pull_ascii_nstring(qname, sizeof(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 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 add_name_to_subnet( wins_server_subnet, qname, name_type,
45 NB_ACTIVE, 2*60*60, DNS_NAME, 1, &addr);
47 return find_name_on_subnet(wins_server_subnet, question, FIND_ANY_NAME);
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 ****************************************************************************/
79 /***************************************************************************
80 handle DNS queries arriving from the parent
81 ****************************************************************************/
82 static void asyncdns_process(void)
84 struct query_record r;
90 if (read_data(fd_in, (char *)&r, sizeof(r)) != sizeof(r))
93 pull_ascii_nstring( qname, sizeof(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);
129 /***************************************************************************
130 create a child process to handle DNS lookups
131 ****************************************************************************/
132 void start_async_dns(void)
138 if (pipe(fd1) || pipe(fd2)) {
139 DEBUG(0,("can't create asyncdns pipes\n"));
143 child_pid = sys_fork();
150 DEBUG(0,("started asyncdns process %d\n", (int)child_pid));
157 CatchSignal(SIGUSR2, SIG_IGN);
158 CatchSignal(SIGUSR1, SIG_IGN);
159 CatchSignal(SIGHUP, SIG_IGN);
160 CatchSignal(SIGTERM, SIGNAL_CAST sig_term );
166 /***************************************************************************
167 check if a particular name is already being queried
168 ****************************************************************************/
169 static BOOL query_current(struct query_record *r)
171 return dns_current &&
172 nmb_name_equal(&r->name,
173 &dns_current->packet.nmb.question.question_name);
177 /***************************************************************************
178 write a query to the child process
179 ****************************************************************************/
180 static BOOL write_child(struct packet_struct *p)
182 struct query_record r;
184 r.name = p->packet.nmb.question.question_name;
186 return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
189 /***************************************************************************
191 ****************************************************************************/
192 void run_dns_queue(void)
194 struct query_record r;
195 struct packet_struct *p, *p2;
196 struct name_record *namerec;
202 /* Allow SIGTERM to kill us. */
203 BlockSignals(False, SIGTERM);
205 if (!process_exists_by_pid(child_pid)) {
211 if ((size=read_data(fd_in, (char *)&r, sizeof(r))) != sizeof(r)) {
213 DEBUG(0,("Incomplete DNS answer from child!\n"));
216 BlockSignals(True, SIGTERM);
220 BlockSignals(True, SIGTERM);
222 namerec = add_dns_result(&r.name, r.result);
225 if (query_current(&r)) {
226 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
229 send_wins_name_query_response(NAM_ERR, dns_current, NULL);
231 send_wins_name_query_response(0,dns_current,namerec);
235 dns_current->locked = False;
236 free_packet(dns_current);
240 /* loop over the whole dns queue looking for entries that
241 match the result we just got */
242 for (p = dns_queue; p;) {
243 struct nmb_packet *nmb = &p->packet.nmb;
244 struct nmb_name *question = &nmb->question.question_name;
246 if (nmb_name_equal(question, &r.name)) {
247 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
250 send_wins_name_query_response(NAM_ERR, p, NULL);
252 send_wins_name_query_response(0,p,namerec);
257 p->prev->next = p->next;
261 p->next->prev = p->prev;
271 dns_current = dns_queue;
272 dns_queue = dns_queue->next;
274 dns_queue->prev = NULL;
275 dns_current->next = NULL;
277 if (!write_child(dns_current)) {
278 DEBUG(3,("failed to send DNS query to child!\n"));
284 /***************************************************************************
286 ****************************************************************************/
288 BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question)
290 if (in_dns || fd_in == -1)
294 if (!write_child(p)) {
295 DEBUG(3,("failed to send DNS query to child!\n"));
309 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
316 /***************************************************************************
317 we use this when we can't do async DNS lookups
318 ****************************************************************************/
320 BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question)
322 struct name_record *namerec = NULL;
323 struct in_addr dns_ip;
326 pull_ascii_nstring(qname, sizeof(qname), question->name);
328 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
330 /* Unblock TERM signal so we can be killed in DNS lookup. */
331 BlockSignals(False, SIGTERM);
333 dns_ip.s_addr = interpret_addr(qname);
335 /* Re-block TERM signal. */
336 BlockSignals(True, SIGTERM);
338 namerec = add_dns_result(question, dns_ip);
339 if(namerec == NULL) {
340 send_wins_name_query_response(NAM_ERR, p, NULL);
342 send_wins_name_query_response(0, p, namerec);
347 /***************************************************************************
348 With sync dns there is no child to kill on SIGTERM.
349 ****************************************************************************/
351 void kill_async_dns_child(void)