s4-dsdb: Modify the repl_meta_data behavior to allow Metadata change on attribute...
[Samba/gebeck_regimport.git] / source3 / nmbd / asyncdns.c
blob9e7707b4102c925f2daf3d50c6af09c022c22832
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(void)
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 = sys_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(nmbd_messaging_context(),
170 nmbd_event_context(),
171 procid_self(), true);
173 if (!NT_STATUS_IS_OK(status)) {
174 DEBUG(0,("reinit_after_fork() failed\n"));
175 smb_panic("reinit_after_fork() failed");
178 asyncdns_process();
182 /***************************************************************************
183 check if a particular name is already being queried
184 ****************************************************************************/
185 static bool query_current(struct query_record *r)
187 return dns_current &&
188 nmb_name_equal(&r->name,
189 &dns_current->packet.nmb.question.question_name);
193 /***************************************************************************
194 write a query to the child process
195 ****************************************************************************/
196 static bool write_child(struct packet_struct *p)
198 struct query_record r;
200 r.name = p->packet.nmb.question.question_name;
202 return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
205 /***************************************************************************
206 check the DNS queue
207 ****************************************************************************/
208 void run_dns_queue(void)
210 struct query_record r;
211 struct packet_struct *p, *p2;
212 struct name_record *namerec;
213 NTSTATUS status;
215 if (fd_in == -1)
216 return;
218 if (!process_exists_by_pid(child_pid)) {
219 close(fd_in);
220 close(fd_out);
221 start_async_dns();
224 status = read_data(fd_in, (char *)&r, sizeof(r));
226 if (!NT_STATUS_IS_OK(status)) {
227 DEBUG(0, ("read from child failed: %s\n", nt_errstr(status)));
228 fd_in = -1;
229 return;
232 namerec = add_dns_result(&r.name, r.result);
234 if (dns_current) {
235 if (query_current(&r)) {
236 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
237 in_dns = 1;
238 if(namerec == NULL)
239 send_wins_name_query_response(NAM_ERR, dns_current, NULL);
240 else
241 send_wins_name_query_response(0,dns_current,namerec);
242 in_dns = 0;
245 dns_current->locked = False;
246 free_packet(dns_current);
247 dns_current = NULL;
250 /* loop over the whole dns queue looking for entries that
251 match the result we just got */
252 for (p = dns_queue; p;) {
253 struct nmb_packet *nmb = &p->packet.nmb;
254 struct nmb_name *question = &nmb->question.question_name;
256 if (nmb_name_equal(question, &r.name)) {
257 DEBUG(3,("DNS calling send_wins_name_query_response\n"));
258 in_dns = 1;
259 if(namerec == NULL)
260 send_wins_name_query_response(NAM_ERR, p, NULL);
261 else
262 send_wins_name_query_response(0,p,namerec);
263 in_dns = 0;
264 p->locked = False;
266 p2 = p->next;
267 DLIST_REMOVE(dns_queue, p);
268 free_packet(p);
269 p = p2;
270 } else {
271 p = p->next;
275 if (dns_queue) {
276 dns_current = dns_queue;
277 DLIST_REMOVE(dns_queue, dns_queue);
279 if (!write_child(dns_current)) {
280 DEBUG(3,("failed to send DNS query to child!\n"));
281 return;
286 /***************************************************************************
287 queue a DNS query
288 ****************************************************************************/
290 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
292 if (in_dns || fd_in == -1)
293 return False;
295 if (!dns_current) {
296 if (!write_child(p)) {
297 DEBUG(3,("failed to send DNS query to child!\n"));
298 return False;
300 dns_current = p;
301 p->locked = True;
302 } else {
303 p->locked = True;
304 DLIST_ADD(dns_queue, p);
307 DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
308 return True;
311 #else
314 /***************************************************************************
315 we use this when we can't do async DNS lookups
316 ****************************************************************************/
318 bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
320 struct name_record *namerec = NULL;
321 struct in_addr dns_ip;
322 unstring qname;
324 pull_ascii_nstring(qname, sizeof(qname), question->name);
326 DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
328 dns_ip.s_addr = interpret_addr(qname);
330 namerec = add_dns_result(question, dns_ip);
331 if(namerec == NULL) {
332 send_wins_name_query_response(NAM_ERR, p, NULL);
333 } else {
334 send_wins_name_query_response(0, p, namerec);
336 return False;
339 /***************************************************************************
340 With sync dns there is no child to kill on SIGTERM.
341 ****************************************************************************/
343 void kill_async_dns_child(void)
345 return;
347 #endif