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