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 3 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, see <http://www.gnu.org/licenses/>.
  20
  21 */
  22
  23 #include "includes.h"
  24 #include "nmbd/nmbd.h"
  25 #include "smbprofile.h"
  26
  27 /* Election parameters. */
  28 extern time_t StartupTime;
  29
  30 /****************************************************************************
  31   Send an election datagram packet.
  32 **************************************************************************/
  33
  34 static void send_election_dgram(struct subnet_record *subrec, const char *workgroup_name,
  35                                 uint32 criterion, int timeup,const char *server_name)
  36 {
  37         char outbuf[1024];
  38         unstring srv_name;
  39         char *p;
  40
  41         DEBUG(2,("send_election_dgram: Sending election packet for workgroup %s on subnet %s\n",
  42                 workgroup_name, subrec->subnet_name ));
  43
  44         memset(outbuf,'\0',sizeof(outbuf));
  45         p = outbuf;
  46         SCVAL(p,0,ANN_Election); /* Election opcode. */
  47         p++;
  48
  49         SCVAL(p,0,((criterion == 0 && timeup == 0) ? 0 : ELECTION_VERSION));
  50         SIVAL(p,1,criterion);
  51         SIVAL(p,5,timeup*1000); /* ms - Despite what the spec says. */
  52         p += 13;
  53         unstrcpy(srv_name, server_name);
  54         strupper_m(srv_name);
  55         /* The following call does UNIX -> DOS charset conversion. */
  56         push_ascii(p, srv_name, sizeof(outbuf)-PTR_DIFF(p,outbuf)-1, STR_TERMINATE);
  57         p = skip_string(outbuf,sizeof(outbuf),p);
  58
  59         send_mailslot(False, BROWSE_MAILSLOT, outbuf, PTR_DIFF(p,outbuf),
  60                 lp_netbios_name(), 0,
  61                 workgroup_name, 0x1e,
  62                 subrec->bcast_ip, subrec->myip, DGRAM_PORT);
  63 }
  64
  65 /*******************************************************************
  66  We found a current master browser on one of our broadcast interfaces.
  67 ******************************************************************/
  68
  69 static void check_for_master_browser_success(struct subnet_record *subrec,
  70                                  struct userdata_struct *userdata,
  71                                  struct nmb_name *answer_name,
  72                                  struct in_addr answer_ip, struct res_rec *rrec)
  73 {
  74         unstring aname;
  75         pull_ascii_nstring(aname, sizeof(aname), answer_name->name);
  76         DEBUG(3,("check_for_master_browser_success: Local master browser for workgroup %s exists at \
  77 IP %s (just checking).\n", aname, inet_ntoa(answer_ip) ));
  78 }
  79
  80 /*******************************************************************
  81  We failed to find a current master browser on one of our broadcast interfaces.
  82 ******************************************************************/
  83
  84 static void check_for_master_browser_fail( struct subnet_record *subrec,
  85                                            struct response_record *rrec,
  86                                            struct nmb_name *question_name,
  87                                            int fail_code)
  88 {
  89         unstring workgroup_name;
  90         struct work_record *work;
  91
  92         pull_ascii_nstring(workgroup_name,sizeof(workgroup_name),question_name->name);
  93
  94         work = find_workgroup_on_subnet(subrec, workgroup_name);
  95         if(work == NULL) {
  96                 DEBUG(0,("check_for_master_browser_fail: Unable to find workgroup %s on subnet %s.=\n",
  97                         workgroup_name, subrec->subnet_name ));
  98                 return;
  99         }
 100
 101         if (strequal(work->work_group, lp_workgroup())) {
 102
 103                 if (lp_local_master()) {
 104                         /* We have discovered that there is no local master
 105                                 browser, and we are configured to initiate
 106                                 an election that we will participate in.
 107                         */
 108                         DEBUG(2,("check_for_master_browser_fail: Forcing election on workgroup %s subnet %s\n",
 109                                 work->work_group, subrec->subnet_name ));
 110
 111                         /* Setting this means we will participate when the
 112                                 election is run in run_elections(). */
 113                         work->needelection = True;
 114                 } else {
 115                         /* We need to force an election, because we are configured
 116                                 not to become the local master, but we still need one,
 117                                 having detected that one doesn't exist.
 118                         */
 119                         send_election_dgram(subrec, work->work_group, 0, 0, "");
 120                 }
 121         }
 122 }
 123
 124 /*******************************************************************
 125   Ensure there is a local master browser for a workgroup on our
 126   broadcast interfaces.
 127 ******************************************************************/
 128
 129 void check_master_browser_exists(time_t t)
 130 {
 131         static time_t lastrun=0;
 132         struct subnet_record *subrec;
 133         const char *workgroup_name = lp_workgroup();
 134
 135         if (t < (lastrun + (CHECK_TIME_MST_BROWSE * 60)))
 136                 return;
 137
 138         lastrun = t;
 139
 140         dump_workgroups(False);
 141
 142         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
 143                 struct work_record *work;
 144
 145                 for (work = subrec->workgrouplist; work; work = work->next) {
 146                         if (strequal(work->work_group, workgroup_name) && !AM_LOCAL_MASTER_BROWSER(work)) {
 147                                 /* Do a name query for the local master browser on this net. */
 148                                 query_name( subrec, work->work_group, 0x1d,
 149                                         check_for_master_browser_success,
 150                                         check_for_master_browser_fail,
 151                                         NULL);
 152                         }
 153                 }
 154         }
 155 }
 156
 157 /*******************************************************************
 158   Run an election.
 159 ******************************************************************/
 160
 161 void run_elections(time_t t)
 162 {
 163         static time_t lastime = 0;
 164
 165         struct subnet_record *subrec;
 166
 167         START_PROFILE(run_elections);
 168
 169         /* Send election packets once every 2 seconds - note */
 170         if (lastime && (t - lastime < 2)) {
 171                 END_PROFILE(run_elections);
 172                 return;
 173         }
 174
 175         lastime = t;
 176
 177         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
 178                 struct work_record *work;
 179
 180                 for (work = subrec->workgrouplist; work; work = work->next) {
 181                         if (work->RunningElection) {
 182                                 /*
 183                                  * We can only run an election for a workgroup if we have
 184                                  * registered the WORKGROUP<1e> name, as that's the name
 185                                  * we must listen to.
 186                                  */
 187                                 struct nmb_name nmbname;
 188
 189                                 make_nmb_name(&nmbname, work->work_group, 0x1e);
 190                                 if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
 191                                         DEBUG(8,("run_elections: Cannot send election packet yet as name %s not \
 192 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
 193                                         continue;
 194                                 }
 195
 196                                 send_election_dgram(subrec, work->work_group, work->ElectionCriterion,
 197                                                 t - StartupTime, lp_netbios_name());
 198
 199                                 if (work->ElectionCount++ >= 4) {
 200                                         /* Won election (4 packets were sent out uncontested. */
 201                                         DEBUG(2,("run_elections: >>> Won election for workgroup %s on subnet %s <<<\n",
 202                                                 work->work_group, subrec->subnet_name ));
 203
 204                                         work->RunningElection = False;
 205
 206                                         become_local_master_browser(subrec, work);
 207                                 }
 208                         }
 209                 }
 210         }
 211         END_PROFILE(run_elections);
 212 }
 213
 214 /*******************************************************************
 215   Determine if I win an election.
 216 ******************************************************************/
 217
 218 static bool win_election(struct work_record *work, int version,
 219                          uint32 criterion, int timeup, const char *server_name)
 220 {
 221         int mytimeup = time(NULL) - StartupTime;
 222         uint32 mycriterion = work->ElectionCriterion;
 223
 224         /* If local master is false then never win in election broadcasts. */
 225         if(!lp_local_master()) {
 226                 DEBUG(3,("win_election: Losing election as local master == False\n"));
 227                 return False;
 228         }
 229
 230         DEBUG(4,("win_election: election comparison: %x:%x %x:%x %d:%d %s:%s\n",
 231                         version, ELECTION_VERSION,
 232                         criterion, mycriterion,
 233                         timeup, mytimeup,
 234                         server_name, lp_netbios_name()));
 235
 236         if (version > ELECTION_VERSION)
 237                 return(False);
 238         if (version < ELECTION_VERSION)
 239                 return(True);
 240
 241         if (criterion > mycriterion)
 242                 return(False);
 243         if (criterion < mycriterion)
 244                 return(True);
 245
 246         if (timeup > mytimeup)
 247                 return(False);
 248         if (timeup < mytimeup)
 249                 return(True);
 250
 251         if (strcasecmp_m(lp_netbios_name(), server_name) > 0)
 252                 return(False);
 253
 254         return(True);
 255 }
 256
 257 /*******************************************************************
 258   Process an incoming election datagram packet.
 259 ******************************************************************/
 260
 261 void process_election(struct subnet_record *subrec, struct packet_struct *p, const char *buf)
 262 {
 263         struct dgram_packet *dgram = &p->packet.dgram;
 264         int version = CVAL(buf,0);
 265         uint32 criterion = IVAL(buf,1);
 266         int timeup = IVAL(buf,5)/1000;
 267         unstring server_name;
 268         struct work_record *work;
 269         unstring workgroup_name;
 270
 271         START_PROFILE(election);
 272
 273         pull_ascii_nstring(server_name, sizeof(server_name), buf+13);
 274         pull_ascii_nstring(workgroup_name, sizeof(workgroup_name), dgram->dest_name.name);
 275
 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                 DEBUG(0,("process_election: Cannot find workgroup %s on subnet %s.\n",
 285                         workgroup_name, subrec->subnet_name ));
 286                 goto done;
 287         }
 288
 289         if (!strequal(work->work_group, lp_workgroup())) {
 290                 DEBUG(3,("process_election: ignoring election request for workgroup %s on subnet %s as this \
 291 is not my workgroup.\n", work->work_group, subrec->subnet_name ));
 292                 goto done;
 293         }
 294
 295         if (win_election(work, version,criterion,timeup,server_name)) {
 296                 /* We take precedence over the requesting server. */
 297                 if (!work->RunningElection) {
 298                         /* We weren't running an election - start running one. */
 299
 300                         work->needelection = True;
 301                         work->ElectionCount=0;
 302                 }
 303
 304                 /* Note that if we were running an election for this workgroup on this
 305                         subnet already, we just ignore the server we take precedence over. */
 306         } else {
 307                 /* We lost. Stop participating. */
 308                 work->needelection = False;
 309
 310                 if (work->RunningElection || AM_LOCAL_MASTER_BROWSER(work)) {
 311                         work->RunningElection = False;
 312                         DEBUG(3,("process_election: >>> Lost election for workgroup %s on subnet %s <<<\n",
 313                                 work->work_group, subrec->subnet_name ));
 314                         if (AM_LOCAL_MASTER_BROWSER(work))
 315                                 unbecome_local_master_browser(subrec, work, False);
 316                 }
 317         }
 318 done:
 319
 320         END_PROFILE(election);
 321 }
 322
 323 /****************************************************************************
 324   This function looks over all the workgroups known on all the broadcast
 325   subnets and decides if a browser election is to be run on that workgroup.
 326   It returns True if any election packets need to be sent (this will then
 327   be done by run_elections().
 328 ***************************************************************************/
 329
 330 bool check_elections(void)
 331 {
 332         struct subnet_record *subrec;
 333         bool run_any_election = False;
 334
 335         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
 336                 struct work_record *work;
 337                 for (work = subrec->workgrouplist; work; work = work->next) {
 338                         if (work->RunningElection) {
 339                                 run_any_election = work->RunningElection;
 340                         }
 341
 342                         /*
 343                          * Start an election if we have any chance of winning.
 344                          * Note this is a change to the previous code, that would
 345                          * only run an election if nmbd was in the potential browser
 346                          * state. We need to run elections in any state if we're told
 347                          * to. JRA.
 348                          */
 349
 350                         if (work->needelection && !work->RunningElection && lp_local_master()) {
 351                                 /*
 352                                  * We can only run an election for a workgroup if we have
 353                                  * registered the WORKGROUP<1e> name, as that's the name
 354                                  * we must listen to.
 355                                  */
 356                                 struct nmb_name nmbname;
 357
 358                                 make_nmb_name(&nmbname, work->work_group, 0x1e);
 359                                 if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
 360                                         DEBUG(8,("check_elections: Cannot send election packet yet as name %s not \
 361 yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
 362                                         continue;
 363                                 }
 364
 365                                 DEBUG(3,("check_elections: >>> Starting election for workgroup %s on subnet %s <<<\n",
 366                                         work->work_group, subrec->subnet_name ));
 367
 368                                 work->ElectionCount = 0;
 369                                 work->RunningElection = True;
 370                                 work->needelection = False;
 371                         }
 372                 }
 373         }
 374         return run_any_election;
 375 }
 376
 377 /****************************************************************************
 378  Process a internal Samba message forcing an election.
 379 ***************************************************************************/
 380
 381 void nmbd_message_election(struct messaging_context *msg,
 382                            void *private_data,
 383                            uint32_t msg_type,
 384                            struct server_id server_id,
 385                            DATA_BLOB *data)
 386 {
 387         struct subnet_record *subrec;
 388
 389         for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
 390                 struct work_record *work;
 391                 for (work = subrec->workgrouplist; work; work = work->next) {
 392                         if (strequal(work->work_group, lp_workgroup())) {
 393                                 work->needelection = True;
 394                                 work->ElectionCount=0;
 395                                 work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
 396                         }
 397                 }
 398         }
 399 }