Modified fix for bugid #784. Based on a patch from moriyama@miraclelinux.com (MORIYAM...
[samba.git] / source3 / nmbd / nmbd_elections.c
1 /* 
2    Unix SMB/CIFS implementation.
3    NBT netbios routines and daemon - version 2
4    Copyright (C) Andrew Tridgell 1994-1998
5    Copyright (C) Luke Kenneth Casson Leighton 1994-1998
6    Copyright (C) Jeremy Allison 1994-2003
7    
8    This program is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 2 of the License, or
11    (at your option) any later version.
12    
13    This program is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17    
18    You should have received a copy of the GNU General Public License
19    along with this program; if not, write to the Free Software
20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21    
22 */
23
24 #include "includes.h"
25
26 /* Election parameters. */
27 extern time_t StartupTime;
28
29 /****************************************************************************
30   Send an election datagram packet.
31 **************************************************************************/
32
33 static void send_election_dgram(struct subnet_record *subrec, const char *workgroup_name,
34                                 uint32 criterion, int timeup,const char *server_name)
35 {
36         pstring outbuf;
37         fstring srv_name;
38         char *p;
39
40         DEBUG(2,("send_election_dgram: Sending election packet for workgroup %s on subnet %s\n",
41                 workgroup_name, subrec->subnet_name ));
42
43         memset(outbuf,'\0',sizeof(outbuf));
44         p = outbuf;
45         SCVAL(p,0,ANN_Election); /* Election opcode. */
46         p++;
47
48         SCVAL(p,0,((criterion == 0 && timeup == 0) ? 0 : ELECTION_VERSION));
49         SIVAL(p,1,criterion);
50         SIVAL(p,5,timeup*1000); /* ms - Despite what the spec says. */
51         p += 13;
52         fstrcpy(srv_name, server_name);
53         strupper_m(srv_name);
54         /* The following call does UNIX -> DOS charset conversion. */
55         pstrcpy_base(p, srv_name, outbuf);
56         p = skip_string(p,1);
57   
58         send_mailslot(False, BROWSE_MAILSLOT, outbuf, PTR_DIFF(p,outbuf),
59                 global_myname(), 0,
60                 workgroup_name, 0x1e,
61                 subrec->bcast_ip, subrec->myip, DGRAM_PORT);
62 }
63
64 /*******************************************************************
65  We found a current master browser on one of our broadcast interfaces.
66 ******************************************************************/
67
68 static void check_for_master_browser_success(struct subnet_record *subrec,
69                                  struct userdata_struct *userdata,
70                                  struct nmb_name *answer_name,
71                                  struct in_addr answer_ip, struct res_rec *rrec)
72 {
73         fstring aname;
74         pull_ascii_nstring(aname, sizeof(aname), answer_name->name);
75         DEBUG(3,("check_for_master_browser_success: Local master browser for workgroup %s exists at \
76 IP %s (just checking).\n", aname, inet_ntoa(answer_ip) ));
77 }
78
79 /*******************************************************************
80  We failed to find a current master browser on one of our broadcast interfaces.
81 ******************************************************************/
82
83 static void check_for_master_browser_fail( struct subnet_record *subrec,
84                                            struct response_record *rrec,
85                                            struct nmb_name *question_name,
86                                            int fail_code)
87 {
88         fstring workgroup_name;
89         struct work_record *work;
90
91         pull_ascii_nstring(workgroup_name,sizeof(workgroup_name),question_name->name);
92
93         work = find_workgroup_on_subnet(subrec, workgroup_name);
94         if(work == NULL) {
95                 DEBUG(0,("check_for_master_browser_fail: Unable to find workgroup %s on subnet %s.=\n",
96                         workgroup_name, subrec->subnet_name ));
97                 return;
98         }
99
100         if (strnequal(work->work_group, lp_workgroup(), sizeof(nstring)-1)) {
101
102                 if (lp_local_master()) {
103                         /* We have discovered that there is no local master
104                                 browser, and we are configured to initiate
105                                 an election that we will participate in.
106                         */
107                         DEBUG(2,("check_for_master_browser_fail: Forcing election on workgroup %s subnet %s\n",
108                                 work->work_group, subrec->subnet_name ));
109
110                         /* Setting this means we will participate when the
111                                 election is run in run_elections(). */
112                         work->needelection = True;
113                 } else {
114                         /* We need to force an election, because we are configured
115                                 not to become the local master, but we still need one,
116                                 having detected that one doesn't exist.
117                         */
118                         send_election_dgram(subrec, work->work_group, 0, 0, "");
119                 }
120         }
121 }
122
123 /*******************************************************************
124   Ensure there is a local master browser for a workgroup on our
125   broadcast interfaces.
126 ******************************************************************/
127
128 void check_master_browser_exists(time_t t)
129 {
130         static time_t lastrun=0;
131         struct subnet_record *subrec;
132         const char *workgroup_name = lp_workgroup();
133
134         if (!lastrun)
135                 lastrun = t;
136
137         if (t < (lastrun + (CHECK_TIME_MST_BROWSE * 60)))
138                 return;
139
140         lastrun = t;
141
142         dump_workgroups(False);
143
144         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
145                 struct work_record *work;
146
147                 for (work = subrec->workgrouplist; work; work = work->next) {
148                         if (strnequal(work->work_group, workgroup_name, sizeof(nstring)-1) && !AM_LOCAL_MASTER_BROWSER(work)) {
149                                 /* Do a name query for the local master browser on this net. */
150                                 query_name( subrec, work->work_group, 0x1d,
151                                         check_for_master_browser_success,
152                                         check_for_master_browser_fail,
153                                         NULL);
154                         }
155                 }
156         }
157 }
158
159 /*******************************************************************
160   Run an election.
161 ******************************************************************/
162
163 void run_elections(time_t t)
164 {
165         static time_t lastime = 0;
166   
167         struct subnet_record *subrec;
168   
169         /* Send election packets once every 2 seconds - note */
170         if (lastime && (t - lastime < 2))
171                 return;
172   
173         lastime = t;
174   
175         START_PROFILE(run_elections);
176         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
177                 struct work_record *work;
178
179                 for (work = subrec->workgrouplist; work; work = work->next) {
180                         if (work->RunningElection) {
181                                 /*
182                                  * We can only run an election for a workgroup if we have
183                                  * registered the WORKGROUP<1e> name, as that's the name
184                                  * we must listen to.
185                                  */
186                                 struct nmb_name nmbname;
187
188                                 make_nmb_name(&nmbname, work->work_group, 0x1e);
189                                 if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
190                                         DEBUG(8,("run_elections: Cannot send election packet yet as name %s not \
191 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
192                                         continue;
193                                 }
194
195                                 send_election_dgram(subrec, work->work_group, work->ElectionCriterion,
196                                                 t - StartupTime, global_myname());
197               
198                                 if (work->ElectionCount++ >= 4) {
199                                         /* Won election (4 packets were sent out uncontested. */
200                                         DEBUG(2,("run_elections: >>> Won election for workgroup %s on subnet %s <<<\n",
201                                                 work->work_group, subrec->subnet_name ));
202
203                                         work->RunningElection = False;
204
205                                         become_local_master_browser(subrec, work);
206                                 }
207                         }
208                 }
209         }
210         END_PROFILE(run_elections);
211 }
212
213 /*******************************************************************
214   Determine if I win an election.
215 ******************************************************************/
216
217 static BOOL win_election(struct work_record *work, int version,
218                          uint32 criterion, int timeup, const char *server_name)
219 {  
220         int mytimeup = time(NULL) - StartupTime;
221         uint32 mycriterion = work->ElectionCriterion;
222
223         /* If local master is false then never win in election broadcasts. */
224         if(!lp_local_master()) {
225                 DEBUG(3,("win_election: Losing election as local master == False\n"));
226                 return False;
227         }
228  
229         DEBUG(4,("win_election: election comparison: %x:%x %x:%x %d:%d %s:%s\n",
230                         version, ELECTION_VERSION,
231                         criterion, mycriterion,
232                         timeup, mytimeup,
233                         server_name, global_myname()));
234
235         if (version > ELECTION_VERSION)
236                 return(False);
237         if (version < ELECTION_VERSION)
238                 return(True);
239   
240         if (criterion > mycriterion)
241                 return(False);
242         if (criterion < mycriterion)
243                 return(True);
244
245         if (timeup > mytimeup)
246                 return(False);
247         if (timeup < mytimeup)
248                 return(True);
249
250         if (StrCaseCmp(global_myname(), server_name) > 0)
251                 return(False);
252   
253         return(True);
254 }
255
256 /*******************************************************************
257   Process an incoming election datagram packet.
258 ******************************************************************/
259
260 void process_election(struct subnet_record *subrec, struct packet_struct *p, char *buf)
261 {
262         struct dgram_packet *dgram = &p->packet.dgram;
263         int version = CVAL(buf,0);
264         uint32 criterion = IVAL(buf,1);
265         int timeup = IVAL(buf,5)/1000;
266         fstring server_name;
267         struct work_record *work;
268         fstring workgroup_name;
269
270         pull_ascii_nstring(server_name, sizeof(server_name), buf+13);
271         pull_ascii_nstring(workgroup_name, sizeof(workgroup_name), dgram->dest_name.name);
272
273         START_PROFILE(election);
274         server_name[15] = 0;  
275
276         DEBUG(3,("process_election: Election request from %s at IP %s on subnet %s for workgroup %s.\n",
277                 server_name,inet_ntoa(p->ip), subrec->subnet_name, workgroup_name ));
278
279         DEBUG(5,("process_election: vers=%d criterion=%08x timeup=%d\n", version,criterion,timeup));
280
281         if(( work = find_workgroup_on_subnet(subrec, workgroup_name)) == NULL) {
282                 DEBUG(0,("process_election: Cannot find workgroup %s on subnet %s.\n",
283                         workgroup_name, subrec->subnet_name ));
284                 goto done;
285         }
286
287         if (!strnequal(work->work_group, lp_workgroup(), sizeof(nstring)-1)) {
288                 DEBUG(3,("process_election: ignoring election request for workgroup %s on subnet %s as this \
289 is not my workgroup.\n", work->work_group, subrec->subnet_name ));
290                 goto done;
291         }
292
293         if (win_election(work, version,criterion,timeup,server_name)) {
294                 /* We take precedence over the requesting server. */
295                 if (!work->RunningElection) {
296                         /* We weren't running an election - start running one. */
297
298                         work->needelection = True;
299                         work->ElectionCount=0;
300                 }
301
302                 /* Note that if we were running an election for this workgroup on this
303                         subnet already, we just ignore the server we take precedence over. */
304         } else {
305                 /* We lost. Stop participating. */
306                 work->needelection = False;
307
308                 if (work->RunningElection || AM_LOCAL_MASTER_BROWSER(work)) {
309                         work->RunningElection = False;
310                         DEBUG(3,("process_election: >>> Lost election for workgroup %s on subnet %s <<<\n",
311                                 work->work_group, subrec->subnet_name ));
312                         if (AM_LOCAL_MASTER_BROWSER(work))
313                                 unbecome_local_master_browser(subrec, work, False);
314                 }
315         }
316 done:
317
318         END_PROFILE(election);
319 }
320
321 /****************************************************************************
322   This function looks over all the workgroups known on all the broadcast
323   subnets and decides if a browser election is to be run on that workgroup.
324   It returns True if any election packets need to be sent (this will then
325   be done by run_elections().
326 ***************************************************************************/
327
328 BOOL check_elections(void)
329 {
330         struct subnet_record *subrec;
331         BOOL run_any_election = False;
332
333         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
334                 struct work_record *work;
335                 for (work = subrec->workgrouplist; work; work = work->next) {
336                         run_any_election |= work->RunningElection;
337
338                         /* 
339                          * Start an election if we have any chance of winning.
340                          * Note this is a change to the previous code, that would
341                          * only run an election if nmbd was in the potential browser
342                          * state. We need to run elections in any state if we're told
343                          * to. JRA.
344                          */
345
346                         if (work->needelection && !work->RunningElection && lp_local_master()) {
347                                 /*
348                                  * We can only run an election for a workgroup if we have
349                                  * registered the WORKGROUP<1e> name, as that's the name
350                                  * we must listen to.
351                                  */
352                                 struct nmb_name nmbname;
353
354                                 make_nmb_name(&nmbname, work->work_group, 0x1e);
355                                 if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
356                                         DEBUG(8,("check_elections: Cannot send election packet yet as name %s not \
357 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
358                                         continue;
359                                 }
360
361                                 DEBUG(3,("check_elections: >>> Starting election for workgroup %s on subnet %s <<<\n",
362                                         work->work_group, subrec->subnet_name ));
363
364                                 work->ElectionCount = 0;
365                                 work->RunningElection = True;
366                                 work->needelection = False;
367                         }
368                 }
369         }
370         return run_any_election;
371 }
372
373 /****************************************************************************
374  Process a internal Samba message forcing an election.
375 ***************************************************************************/
376
377 void nmbd_message_election(int msg_type, pid_t src, void *buf, size_t len)
378 {
379         struct subnet_record *subrec;
380
381         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
382                 struct work_record *work;
383                 for (work = subrec->workgrouplist; work; work = work->next) {
384                         if (strnequal(work->work_group, lp_workgroup(), sizeof(nstring)-1)) {
385                                 work->needelection = True;
386                                 work->ElectionCount=0;
387                                 work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
388                         }
389                 }
390         }
391 }