source/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 1994-1998
   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 static void send_election_dgram(struct subnet_record *subrec, const char *workgroup_name,
  33                                 uint32 criterion, int timeup,const char *server_name)
  34 {
  35   pstring outbuf;
  36   char *p;
  37
  38   DEBUG(2,("send_election_dgram: Sending election packet for workgroup %s on subnet %s\n",
  39         workgroup_name, subrec->subnet_name ));
  40
  41   memset(outbuf,'\0',sizeof(outbuf));
  42   p = outbuf;
  43   SCVAL(p,0,ANN_Election); /* Election opcode. */
  44   p++;
  45
  46   SCVAL(p,0,((criterion == 0 && timeup == 0) ? 0 : ELECTION_VERSION));
  47   SIVAL(p,1,criterion);
  48   SIVAL(p,5,timeup*1000); /* ms - Despite what the spec says. */
  49   p += 13;
  50   pstrcpy_base(p, server_name, outbuf);
  51   strupper(p);
  52   p = skip_string(p,1);
  53
  54   send_mailslot(False, BROWSE_MAILSLOT, outbuf, PTR_DIFF(p,outbuf),
  55                 global_myname(), 0,
  56                 workgroup_name, 0x1e,
  57                 subrec->bcast_ip, subrec->myip, DGRAM_PORT);
  58 }
  59
  60 /*******************************************************************
  61  We found a current master browser on one of our broadcast interfaces.
  62 ******************************************************************/
  63
  64 static void check_for_master_browser_success(struct subnet_record *subrec,
  65                                  struct userdata_struct *userdata,
  66                                  struct nmb_name *answer_name,
  67                                  struct in_addr answer_ip, struct res_rec *rrec)
  68 {
  69   DEBUG(3,("check_for_master_browser_success: Local master browser for workgroup %s exists at \
  70 IP %s (just checking).\n", answer_name->name, inet_ntoa(answer_ip) ));
  71 }
  72
  73 /*******************************************************************
  74  We failed to find a current master browser on one of our broadcast interfaces.
  75 ******************************************************************/
  76
  77 static void check_for_master_browser_fail( struct subnet_record *subrec,
  78                                            struct response_record *rrec,
  79                                            struct nmb_name *question_name,
  80                                            int fail_code)
  81 {
  82   char *workgroup_name = question_name->name;
  83   struct work_record *work = find_workgroup_on_subnet(subrec, workgroup_name);
  84
  85   if(work == NULL)
  86   {
  87     DEBUG(0,("check_for_master_browser_fail: Unable to find workgroup %s on subnet %s.=\n",
  88           workgroup_name, subrec->subnet_name ));
  89     return;
  90   }
  91
  92   if (strequal(work->work_group, lp_workgroup()))
  93   {
  94
  95     if (lp_local_master())
  96     {
  97       /* We have discovered that there is no local master
  98          browser, and we are configured to initiate
  99          an election that we will participate in.
 100        */
 101       DEBUG(2,("check_for_master_browser_fail: Forcing election on workgroup %s subnet %s\n",
 102                work->work_group, subrec->subnet_name ));
 103
 104       /* Setting this means we will participate when the
 105          election is run in run_elections(). */
 106       work->needelection = True;
 107     }
 108     else
 109     {
 110       /* We need to force an election, because we are configured
 111          not to become the local master, but we still need one,
 112          having detected that one doesn't exist.
 113        */
 114       send_election_dgram(subrec, work->work_group, 0, 0, "");
 115     }
 116   }
 117 }
 118
 119 /*******************************************************************
 120   Ensure there is a local master browser for a workgroup on our
 121   broadcast interfaces.
 122 ******************************************************************/
 123
 124 void check_master_browser_exists(time_t t)
 125 {
 126   static time_t lastrun=0;
 127   struct subnet_record *subrec;
 128   const char *workgroup_name = lp_workgroup();
 129
 130   if (!lastrun)
 131     lastrun = t;
 132
 133   if (t < (lastrun + (CHECK_TIME_MST_BROWSE * 60)))
 134     return;
 135
 136   lastrun = t;
 137
 138   dump_workgroups(False);
 139
 140   for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec))
 141   {
 142     struct work_record *work;
 143
 144     for (work = subrec->workgrouplist; work; work = work->next)
 145     {
 146       if (strequal(work->work_group, workgroup_name) && !AM_LOCAL_MASTER_BROWSER(work))
 147       {
 148         /* Do a name query for the local master browser on this net. */
 149         query_name( subrec, work->work_group, 0x1d,
 150                     check_for_master_browser_success,
 151                     check_for_master_browser_fail,
 152                     NULL);
 153       }
 154     }
 155   }
 156 }
 157
 158 /*******************************************************************
 159   Run an election.
 160 ******************************************************************/
 161
 162 void run_elections(time_t t)
 163 {
 164   static time_t lastime = 0;
 165
 166   struct subnet_record *subrec;
 167
 168   /* Send election packets once every 2 seconds - note */
 169   if (lastime && (t - lastime < 2))
 170     return;
 171
 172   lastime = t;
 173
 174   START_PROFILE(run_elections);
 175   for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec))
 176   {
 177     struct work_record *work;
 178
 179     for (work = subrec->workgrouplist; work; work = work->next)
 180     {
 181       if (work->RunningElection)
 182       {
 183         /*
 184          * We can only run an election for a workgroup if we have
 185          * registered the WORKGROUP<1e> name, as that's the name
 186          * we must listen to.
 187          */
 188         struct nmb_name nmbname;
 189
 190         make_nmb_name(&nmbname, work->work_group, 0x1e);
 191         if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
 192           DEBUG(8,("run_elections: Cannot send election packet yet as name %s not \
 193 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
 194           continue;
 195         }
 196
 197         send_election_dgram(subrec, work->work_group, work->ElectionCriterion,
 198                       t - StartupTime, global_myname());
 199
 200         if (work->ElectionCount++ >= 4)
 201         {
 202           /* Won election (4 packets were sent out uncontested. */
 203           DEBUG(2,("run_elections: >>> Won election for workgroup %s on subnet %s <<<\n",
 204                     work->work_group, subrec->subnet_name ));
 205
 206           work->RunningElection = False;
 207
 208           become_local_master_browser(subrec, work);
 209         }
 210       }
 211     }
 212   }
 213   END_PROFILE(run_elections);
 214 }
 215
 216 /*******************************************************************
 217   Determine if I win an election.
 218 ******************************************************************/
 219
 220 static BOOL win_election(struct work_record *work, int version,
 221                          uint32 criterion, int timeup, char *server_name)
 222 {
 223   int mytimeup = time(NULL) - StartupTime;
 224   uint32 mycriterion = work->ElectionCriterion;
 225
 226   /* If local master is false then never win
 227      in election broadcasts. */
 228   if(!lp_local_master())
 229   {
 230     DEBUG(3,("win_election: Losing election as local master == False\n"));
 231     return False;
 232   }
 233
 234   DEBUG(4,("win_election: election comparison: %x:%x %x:%x %d:%d %s:%s\n",
 235         version, ELECTION_VERSION,
 236         criterion, mycriterion,
 237         timeup, mytimeup,
 238         server_name, global_myname()));
 239
 240   if (version > ELECTION_VERSION)
 241     return(False);
 242   if (version < ELECTION_VERSION)
 243     return(True);
 244
 245   if (criterion > mycriterion)
 246     return(False);
 247   if (criterion < mycriterion)
 248     return(True);
 249
 250   if (timeup > mytimeup)
 251     return(False);
 252   if (timeup < mytimeup)
 253     return(True);
 254
 255   if (strcasecmp(global_myname(), server_name) > 0)
 256     return(False);
 257
 258   return(True);
 259 }
 260
 261 /*******************************************************************
 262   Process an incoming election datagram packet.
 263 ******************************************************************/
 264
 265 void process_election(struct subnet_record *subrec, struct packet_struct *p, char *buf)
 266 {
 267   struct dgram_packet *dgram = &p->packet.dgram;
 268   int version = CVAL(buf,0);
 269   uint32 criterion = IVAL(buf,1);
 270   int timeup = IVAL(buf,5)/1000;
 271   char *server_name = buf+13;
 272   struct work_record *work;
 273   char *workgroup_name = dgram->dest_name.name;
 274
 275   START_PROFILE(election);
 276   server_name[15] = 0;
 277
 278   DEBUG(3,("process_election: Election request from %s at IP %s on subnet %s for workgroup %s.\n",
 279       server_name,inet_ntoa(p->ip), subrec->subnet_name, workgroup_name ));
 280
 281   DEBUG(5,("process_election: vers=%d criterion=%08x timeup=%d\n", version,criterion,timeup));
 282
 283   if(( work = find_workgroup_on_subnet(subrec, workgroup_name)) == NULL)
 284   {
 285     DEBUG(0,("process_election: Cannot find workgroup %s on subnet %s.\n",
 286           workgroup_name, subrec->subnet_name ));
 287     goto done;
 288   }
 289
 290   if (!strequal(work->work_group, lp_workgroup()))
 291   {
 292     DEBUG(3,("process_election: ignoring election request for workgroup %s on subnet %s as this \
 293 is not my workgroup.\n", work->work_group, subrec->subnet_name ));
 294     goto done;
 295   }
 296
 297   if (win_election(work, version,criterion,timeup,server_name))
 298   {
 299     /* We take precedence over the requesting server. */
 300     if (!work->RunningElection)
 301     {
 302       /* We weren't running an election - start running one. */
 303
 304       work->needelection = True;
 305       work->ElectionCount=0;
 306     }
 307
 308     /* Note that if we were running an election for this workgroup on this
 309        subnet already, we just ignore the server we take precedence over. */
 310   }
 311   else
 312   {
 313     /* We lost. Stop participating. */
 314     work->needelection = False;
 315
 316     if (work->RunningElection || AM_LOCAL_MASTER_BROWSER(work))
 317     {
 318       work->RunningElection = False;
 319       DEBUG(3,("process_election: >>> Lost election for workgroup %s on subnet %s <<<\n",
 320             work->work_group, subrec->subnet_name ));
 321       if (AM_LOCAL_MASTER_BROWSER(work))
 322         unbecome_local_master_browser(subrec, work, False);
 323     }
 324   }
 325 done:
 326   END_PROFILE(election);
 327 }
 328
 329 /****************************************************************************
 330   This function looks over all the workgroups known on all the broadcast
 331   subnets and decides if a browser election is to be run on that workgroup.
 332   It returns True if any election packets need to be sent (this will then
 333   be done by run_elections().
 334 ***************************************************************************/
 335
 336 BOOL check_elections(void)
 337 {
 338   struct subnet_record *subrec;
 339   BOOL run_any_election = False;
 340
 341   for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec))
 342   {
 343     struct work_record *work;
 344     for (work = subrec->workgrouplist; work; work = work->next)
 345     {
 346       run_any_election |= work->RunningElection;
 347
 348       /*
 349        * Start an election if we have any chance of winning.
 350        * Note this is a change to the previous code, that would
 351        * only run an election if nmbd was in the potential browser
 352        * state. We need to run elections in any state if we're told
 353        * to. JRA.
 354        */
 355
 356       if (work->needelection && !work->RunningElection && lp_local_master())
 357       {
 358         /*
 359          * We can only run an election for a workgroup if we have
 360          * registered the WORKGROUP<1e> name, as that's the name
 361          * we must listen to.
 362          */
 363         struct nmb_name nmbname;
 364
 365         make_nmb_name(&nmbname, work->work_group, 0x1e);
 366         if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
 367           DEBUG(8,("check_elections: Cannot send election packet yet as name %s not \
 368 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
 369           continue;
 370         }
 371
 372         DEBUG(3,("check_elections: >>> Starting election for workgroup %s on subnet %s <<<\n",
 373               work->work_group, subrec->subnet_name ));
 374
 375         work->ElectionCount = 0;
 376         work->RunningElection = True;
 377         work->needelection = False;
 378       }
 379     }
 380   }
 381   return run_any_election;
 382 }
 383
 384
 385
 386 /****************************************************************************
 387 process a internal Samba message forcing an election
 388 ***************************************************************************/
 389 void nmbd_message_election(int msg_type, pid_t src, void *buf, size_t len)
 390 {
 391         struct subnet_record *subrec;
 392
 393         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
 394                 struct work_record *work;
 395                 for (work = subrec->workgrouplist; work; work = work->next) {
 396                         if (strequal(work->work_group, lp_workgroup())) {
 397                                 work->needelection = True;
 398                                 work->ElectionCount=0;
 399                                 work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
 400                         }
 401                 }
 402         }
 403 }