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/>.
21 #include "nmbd/nmbd.h"
22 #include "lib/util/sys_rw_data.h"
24 /***************************************************************************
25 Add a DNS result to the name cache.
26 ****************************************************************************/
28 static struct name_record *add_dns_result(struct nmb_name *question, struct in_addr addr)
30 int name_type = question->name_type;
33 pull_ascii_nstring(qname, sizeof(qname), question->name);
36 /* add the fail to WINS cache of names. give it 1 hour in the cache */
37 DEBUG(3,("add_dns_result: Negative DNS answer for %s\n", qname));
38 add_name_to_subnet( wins_server_subnet, qname, name_type,
39 NB_ACTIVE, 60*60, DNSFAIL_NAME, 1, &addr );
43 /* add it to our WINS cache of names. give it 2 hours in the cache */
44 DEBUG(3,("add_dns_result: DNS gave answer for %s of %s\n", qname, inet_ntoa(addr)));
46 add_name_to_subnet( wins_server_subnet, qname, name_type,
47 NB_ACTIVE, 2*60*60, DNS_NAME, 1, &addr);
49 return find_name_on_subnet(wins_server_subnet, question, FIND_ANY_NAME);
54 static int fd_in = -1, fd_out = -1;
55 static pid_t child_pid = -1;
58 /* this is the structure that is passed between the parent and child */
61 struct in_addr result;
64 /* a queue of pending requests waiting to be sent to the DNS child */
65 static struct packet_struct *dns_queue;
67 /* the packet currently being processed by the dns child */
68 static struct packet_struct *dns_current;
71 /***************************************************************************
72 return the fd used to gather async dns replies. This is added to the select
74 ****************************************************************************/
81 /***************************************************************************
82 handle DNS queries arriving from the parent
83 ****************************************************************************/
84 static void asyncdns_process(void)
86 struct query_record r;
94 status = read_data_ntstatus(fd_in, (char *)&r, sizeof(r));
96 if (!NT_STATUS_IS_OK(status)) {
100 pull_ascii_nstring( qname, sizeof(qname), r.name.name);
101 r.result.s_addr = interpret_addr(qname);
103 if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r))
110 /**************************************************************************** **
111 catch a sigterm (in the child process - the parent has a different handler
112 see nmbd.c for details).
113 We need a separate term handler here so we don't release any
114 names that our parent is going to release, or overwrite a
115 WINS db that our parent is going to write.
116 **************************************************************************** */
118 static void sig_term(int sig)
123 /***************************************************************************
124 Called by the parent process when it receives a SIGTERM - also kills the
125 child so we don't get child async dns processes lying around, causing trouble.
126 ****************************************************************************/
128 void kill_async_dns_child(void)
131 kill(child_pid, SIGTERM);
136 /***************************************************************************
137 create a child process to handle DNS lookups
138 ****************************************************************************/
139 void start_async_dns(struct messaging_context *msg)
146 if (pipe(fd1) || pipe(fd2)) {
147 DEBUG(0,("can't create asyncdns pipes\n"));
158 DEBUG(0,("started asyncdns process %d\n", (int)child_pid));
165 CatchSignal(SIGUSR2, SIG_IGN);
166 CatchSignal(SIGUSR1, SIG_IGN);
167 CatchSignal(SIGHUP, SIG_IGN);
168 CatchSignal(SIGTERM, sig_term);
170 status = reinit_after_fork(msg, nmbd_event_context(), true, NULL);
172 if (!NT_STATUS_IS_OK(status)) {
173 DEBUG(0,("reinit_after_fork() failed\n"));
174 smb_panic("reinit_after_fork() failed");
181 /***************************************************************************
182 check if a particular name is already being queried
183 ****************************************************************************/
184 static bool query_current(struct query_record *r)
186 return dns_current &&
187 nmb_name_equal(&r->name,
188 &dns_current->packet.nmb.question.question_name);
192 /***************************************************************************
193 write a query to the child process
194 ****************************************************************************/
195 static bool write_child(struct packet_struct *p)
197 struct query_record r;
199 r.name = p->packet.nmb.question.question_name;
201 return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
204 /***************************************************************************
206 ****************************************************************************/
207 void run_dns_queue(struct messaging_context *msg)
209 struct query_record r;
210 struct packet_struct *p, *p2;
211 struct name_record *namerec;
217 if (!process_exists_by_pid(child_pid)) {
220 start_async_dns(msg);
223 status = read_data_ntstatus(fd_in, (char *)&r, sizeof(r));
225 if (!NT_STATUS_IS_OK(status)) {
226 DEBUG(0, ("read from child failed: %s\n", nt_errstr(status)));
231 namerec = add_dns_result(&r.name, r.result);
234 if (query_current(&r)) {
235 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
238 send_wins_name_query_response(NAM_ERR, dns_current, NULL);
240 send_wins_name_query_response(0,dns_current,namerec);
244 dns_current->locked = False;
245 free_packet(dns_current);
249 /* loop over the whole dns queue looking for entries that
250 match the result we just got */
251 for (p = dns_queue; p;) {
252 struct nmb_packet *nmb = &p->packet.nmb;
253 struct nmb_name *question = &nmb->question.question_name;
255 if (nmb_name_equal(question, &r.name)) {
256 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
259 send_wins_name_query_response(NAM_ERR, p, NULL);
261 send_wins_name_query_response(0,p,namerec);
266 DLIST_REMOVE(dns_queue, p);
275 dns_current = dns_queue;
276 DLIST_REMOVE(dns_queue, dns_queue);
278 if (!write_child(dns_current)) {
279 DEBUG(3,("failed to send DNS query to child!\n"));
285 /***************************************************************************
287 ****************************************************************************/
289 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
291 if (in_dns || fd_in == -1)
295 if (!write_child(p)) {
296 DEBUG(3,("failed to send DNS query to child!\n"));
303 DLIST_ADD(dns_queue, p);
306 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
313 /***************************************************************************
314 we use this when we can't do async DNS lookups
315 ****************************************************************************/
317 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
319 struct name_record *namerec = NULL;
320 struct in_addr dns_ip;
323 pull_ascii_nstring(qname, sizeof(qname), question->name);
325 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
327 dns_ip.s_addr = interpret_addr(qname);
329 namerec = add_dns_result(question, dns_ip);
330 if(namerec == NULL) {
331 send_wins_name_query_response(NAM_ERR, p, NULL);
333 send_wins_name_query_response(0, p, namerec);
338 /***************************************************************************
339 With sync dns there is no child to kill on SIGTERM.
340 ****************************************************************************/
342 void kill_async_dns_child(void)