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;
92 status = read_data(fd_in, (char *)&r, sizeof(r));
94 if (!NT_STATUS_IS_OK(status)) {
98 pull_ascii_nstring( qname, sizeof(qname), r.name.name);
99 r.result.s_addr = interpret_addr(qname);
101 if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r))
108 /**************************************************************************** **
109 catch a sigterm (in the child process - the parent has a different handler
110 see nmbd.c for details).
111 We need a separate term handler here so we don't release any
112 names that our parent is going to release, or overwrite a
113 WINS db that our parent is going to write.
114 **************************************************************************** */
116 static void sig_term(int sig)
121 /***************************************************************************
122 Called by the parent process when it receives a SIGTERM - also kills the
123 child so we don't get child async dns processes lying around, causing trouble.
124 ****************************************************************************/
126 void kill_async_dns_child(void)
129 kill(child_pid, SIGTERM);
134 /***************************************************************************
135 create a child process to handle DNS lookups
136 ****************************************************************************/
137 void start_async_dns(void)
143 if (pipe(fd1) || pipe(fd2)) {
144 DEBUG(0,("can't create asyncdns pipes\n"));
148 child_pid = sys_fork();
155 DEBUG(0,("started asyncdns process %d\n", (int)child_pid));
162 CatchSignal(SIGUSR2, SIG_IGN);
163 CatchSignal(SIGUSR1, SIG_IGN);
164 CatchSignal(SIGHUP, SIG_IGN);
165 CatchSignal(SIGTERM, SIGNAL_CAST sig_term );
167 if (!reinit_after_fork(nmbd_messaging_context(),
168 nmbd_event_context(), true)) {
169 DEBUG(0,("reinit_after_fork() failed\n"));
170 smb_panic("reinit_after_fork() failed");
177 /***************************************************************************
178 check if a particular name is already being queried
179 ****************************************************************************/
180 static bool query_current(struct query_record *r)
182 return dns_current &&
183 nmb_name_equal(&r->name,
184 &dns_current->packet.nmb.question.question_name);
188 /***************************************************************************
189 write a query to the child process
190 ****************************************************************************/
191 static bool write_child(struct packet_struct *p)
193 struct query_record r;
195 r.name = p->packet.nmb.question.question_name;
197 return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
200 /***************************************************************************
202 ****************************************************************************/
203 void run_dns_queue(void)
205 struct query_record r;
206 struct packet_struct *p, *p2;
207 struct name_record *namerec;
213 /* Allow SIGTERM to kill us. */
214 BlockSignals(False, SIGTERM);
216 if (!process_exists_by_pid(child_pid)) {
222 status = read_data(fd_in, (char *)&r, sizeof(r));
224 if (!NT_STATUS_IS_OK(status)) {
225 DEBUG(0, ("read from child failed: %s\n", nt_errstr(status)));
227 BlockSignals(True, SIGTERM);
231 BlockSignals(True, SIGTERM);
233 namerec = add_dns_result(&r.name, r.result);
236 if (query_current(&r)) {
237 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
240 send_wins_name_query_response(NAM_ERR, dns_current, NULL);
242 send_wins_name_query_response(0,dns_current,namerec);
246 dns_current->locked = False;
247 free_packet(dns_current);
251 /* loop over the whole dns queue looking for entries that
252 match the result we just got */
253 for (p = dns_queue; p;) {
254 struct nmb_packet *nmb = &p->packet.nmb;
255 struct nmb_name *question = &nmb->question.question_name;
257 if (nmb_name_equal(question, &r.name)) {
258 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
261 send_wins_name_query_response(NAM_ERR, p, NULL);
263 send_wins_name_query_response(0,p,namerec);
268 p->prev->next = p->next;
272 p->next->prev = p->prev;
282 dns_current = dns_queue;
283 dns_queue = dns_queue->next;
285 dns_queue->prev = NULL;
286 dns_current->next = NULL;
288 if (!write_child(dns_current)) {
289 DEBUG(3,("failed to send DNS query to child!\n"));
295 /***************************************************************************
297 ****************************************************************************/
299 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
301 if (in_dns || fd_in == -1)
305 if (!write_child(p)) {
306 DEBUG(3,("failed to send DNS query to child!\n"));
320 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
327 /***************************************************************************
328 we use this when we can't do async DNS lookups
329 ****************************************************************************/
331 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
333 struct name_record *namerec = NULL;
334 struct in_addr dns_ip;
337 pull_ascii_nstring(qname, sizeof(qname), question->name);
339 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
341 /* Unblock TERM signal so we can be killed in DNS lookup. */
342 BlockSignals(False, SIGTERM);
344 dns_ip.s_addr = interpret_addr(qname);
346 /* Re-block TERM signal. */
347 BlockSignals(True, SIGTERM);
349 namerec = add_dns_result(question, dns_ip);
350 if(namerec == NULL) {
351 send_wins_name_query_response(NAM_ERR, p, NULL);
353 send_wins_name_query_response(0, p, namerec);
358 /***************************************************************************
359 With sync dns there is no child to kill on SIGTERM.
360 ****************************************************************************/
362 void kill_async_dns_child(void)