s3:smbXsrv_tcon: add smbXsrv_tcon_global_traverse()
[Samba.git] / source3 / nmbd / asyncdns.c
blob90340efe3970600195f9f2462da0303adbcbec76
1 /*
2 Unix SMB/CIFS implementation.
3 a async DNS handler
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/>.
20 #include "includes.h"
21 #include "nmbd/nmbd.h"
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 unstring qname;
32 pull_ascii_nstring(qname, sizeof(qname), question->name);
34 if (!addr.s_addr) {
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 add_name_to_subnet( wins_server_subnet, qname, name_type,
38 NB_ACTIVE, 60*60, DNSFAIL_NAME, 1, &addr );
39 return NULL;
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 add_name_to_subnet( wins_server_subnet, qname, name_type,
46 NB_ACTIVE, 2*60*60, DNS_NAME, 1, &addr);
48 return find_name_on_subnet(wins_server_subnet, question, FIND_ANY_NAME);
51 #ifndef SYNC_DNS
53 static int fd_in = -1, fd_out = -1;
54 static pid_t child_pid = -1;
55 static int in_dns;
57 /* this is the structure that is passed between the parent and child */
58 struct query_record {
59 struct nmb_name name;
60 struct in_addr result;
63 /* a queue of pending requests waiting to be sent to the DNS child */
64 static struct packet_struct *dns_queue;
66 /* the packet currently being processed by the dns child */
67 static struct packet_struct *dns_current;
70 /***************************************************************************
71 return the fd used to gather async dns replies. This is added to the select
72 loop
73 ****************************************************************************/
75 int asyncdns_fd(void)
77 return fd_in;
80 /***************************************************************************
81 handle DNS queries arriving from the parent
82 ****************************************************************************/
83 static void asyncdns_process(void)
85 struct query_record r;
86 unstring qname;
88 DEBUGLEVEL = -1;
90 while (1) {
91 NTSTATUS status;
93 status = read_data(fd_in, (char *)&r, sizeof(r));
95 if (!NT_STATUS_IS_OK(status)) {
96 break;
99 pull_ascii_nstring( qname, sizeof(qname), r.name.name);
100 r.result.s_addr = interpret_addr(qname);
102 if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r))
103 break;
106 _exit(0);
109 /**************************************************************************** **
110 catch a sigterm (in the child process - the parent has a different handler
111 see nmbd.c for details).
112 We need a separate term handler here so we don't release any
113 names that our parent is going to release, or overwrite a
114 WINS db that our parent is going to write.
115 **************************************************************************** */
117 static void sig_term(int sig)
119 _exit(0);
122 /***************************************************************************
123 Called by the parent process when it receives a SIGTERM - also kills the
124 child so we don't get child async dns processes lying around, causing trouble.
125 ****************************************************************************/
127 void kill_async_dns_child(void)
129 if (child_pid > 0) {
130 kill(child_pid, SIGTERM);
131 child_pid = -1;
135 /***************************************************************************
136 create a child process to handle DNS lookups
137 ****************************************************************************/
138 void start_async_dns(struct messaging_context *msg)
140 int fd1[2], fd2[2];
141 NTSTATUS status;
143 CatchChild();
145 if (pipe(fd1) || pipe(fd2)) {
146 DEBUG(0,("can't create asyncdns pipes\n"));
147 return;
150 child_pid = fork();
152 if (child_pid) {
153 fd_in = fd1[0];
154 fd_out = fd2[1];
155 close(fd1[1]);
156 close(fd2[0]);
157 DEBUG(0,("started asyncdns process %d\n", (int)child_pid));
158 return;
161 fd_in = fd2[0];
162 fd_out = fd1[1];
164 CatchSignal(SIGUSR2, SIG_IGN);
165 CatchSignal(SIGUSR1, SIG_IGN);
166 CatchSignal(SIGHUP, SIG_IGN);
167 CatchSignal(SIGTERM, sig_term);
169 status = reinit_after_fork(msg, nmbd_event_context(), true);
171 if (!NT_STATUS_IS_OK(status)) {
172 DEBUG(0,("reinit_after_fork() failed\n"));
173 smb_panic("reinit_after_fork() failed");
176 asyncdns_process();
180 /***************************************************************************
181 check if a particular name is already being queried
182 ****************************************************************************/
183 static bool query_current(struct query_record *r)
185 return dns_current &&
186 nmb_name_equal(&r->name,
187 &dns_current->packet.nmb.question.question_name);
191 /***************************************************************************
192 write a query to the child process
193 ****************************************************************************/
194 static bool write_child(struct packet_struct *p)
196 struct query_record r;
198 r.name = p->packet.nmb.question.question_name;
200 return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
203 /***************************************************************************
204 check the DNS queue
205 ****************************************************************************/
206 void run_dns_queue(struct messaging_context *msg)
208 struct query_record r;
209 struct packet_struct *p, *p2;
210 struct name_record *namerec;
211 NTSTATUS status;
213 if (fd_in == -1)
214 return;
216 if (!process_exists_by_pid(child_pid)) {
217 close(fd_in);
218 close(fd_out);
219 start_async_dns(msg);
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)));
226 fd_in = -1;
227 return;
230 namerec = add_dns_result(&r.name, r.result);
232 if (dns_current) {
233 if (query_current(&r)) {
234 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
235 in_dns = 1;
236 if(namerec == NULL)
237 send_wins_name_query_response(NAM_ERR, dns_current, NULL);
238 else
239 send_wins_name_query_response(0,dns_current,namerec);
240 in_dns = 0;
243 dns_current->locked = False;
244 free_packet(dns_current);
245 dns_current = NULL;
248 /* loop over the whole dns queue looking for entries that
249 match the result we just got */
250 for (p = dns_queue; p;) {
251 struct nmb_packet *nmb = &p->packet.nmb;
252 struct nmb_name *question = &nmb->question.question_name;
254 if (nmb_name_equal(question, &r.name)) {
255 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
256 in_dns = 1;
257 if(namerec == NULL)
258 send_wins_name_query_response(NAM_ERR, p, NULL);
259 else
260 send_wins_name_query_response(0,p,namerec);
261 in_dns = 0;
262 p->locked = False;
264 p2 = p->next;
265 DLIST_REMOVE(dns_queue, p);
266 free_packet(p);
267 p = p2;
268 } else {
269 p = p->next;
273 if (dns_queue) {
274 dns_current = dns_queue;
275 DLIST_REMOVE(dns_queue, dns_queue);
277 if (!write_child(dns_current)) {
278 DEBUG(3,("failed to send DNS query to child!\n"));
279 return;
284 /***************************************************************************
285 queue a DNS query
286 ****************************************************************************/
288 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
290 if (in_dns || fd_in == -1)
291 return False;
293 if (!dns_current) {
294 if (!write_child(p)) {
295 DEBUG(3,("failed to send DNS query to child!\n"));
296 return False;
298 dns_current = p;
299 p->locked = True;
300 } else {
301 p->locked = True;
302 DLIST_ADD(dns_queue, p);
305 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
306 return True;
309 #else
312 /***************************************************************************
313 we use this when we can't do async DNS lookups
314 ****************************************************************************/
316 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
318 struct name_record *namerec = NULL;
319 struct in_addr dns_ip;
320 unstring qname;
322 pull_ascii_nstring(qname, sizeof(qname), question->name);
324 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
326 dns_ip.s_addr = interpret_addr(qname);
328 namerec = add_dns_result(question, dns_ip);
329 if(namerec == NULL) {
330 send_wins_name_query_response(NAM_ERR, p, NULL);
331 } else {
332 send_wins_name_query_response(0, p, namerec);
334 return False;
337 /***************************************************************************
338 With sync dns there is no child to kill on SIGTERM.
339 ****************************************************************************/
341 void kill_async_dns_child(void)
343 return;
345 #endif