diff options
Diffstat (limited to 'source3/nmbd/nmbd_elections.c')
| -rw-r--r-- | source3/nmbd/nmbd_elections.c | 395 |
1 files changed, 395 insertions, 0 deletions
diff --git a/source3/nmbd/nmbd_elections.c b/source3/nmbd/nmbd_elections.c new file mode 100644 index 0000000..41470ea --- /dev/null +++ b/source3/nmbd/nmbd_elections.c @@ -0,0 +1,395 @@ +/* + Unix SMB/CIFS implementation. + NBT netbios routines and daemon - version 2 + Copyright (C) Andrew Tridgell 1994-1998 + Copyright (C) Luke Kenneth Casson Leighton 1994-1998 + Copyright (C) Jeremy Allison 1994-2003 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. + +*/ + +#include "includes.h" +#include "nmbd/nmbd.h" +#include "lib/util/string_wrappers.h" + +/* Election parameters. */ +extern time_t StartupTime; + +/**************************************************************************** + Send an election datagram packet. +**************************************************************************/ + +static void send_election_dgram(struct subnet_record *subrec, const char *workgroup_name, + uint32_t criterion, int timeup,const char *server_name) +{ + char outbuf[1024]; + unstring srv_name; + char *p; + + DEBUG(2,("send_election_dgram: Sending election packet for workgroup %s on subnet %s\n", + workgroup_name, subrec->subnet_name )); + + memset(outbuf,'\0',sizeof(outbuf)); + p = outbuf; + SCVAL(p,0,ANN_Election); /* Election opcode. */ + p++; + + SCVAL(p,0,((criterion == 0 && timeup == 0) ? 0 : ELECTION_VERSION)); + SIVAL(p,1,criterion); + SIVAL(p,5,timeup*1000); /* ms - Despite what the spec says. */ + p += 13; + unstrcpy(srv_name, server_name); + if (!strupper_m(srv_name)) { + DEBUG(2,("strupper_m failed for %s\n", srv_name)); + return; + } + /* The following call does UNIX -> DOS charset conversion. */ + push_ascii(p, srv_name, sizeof(outbuf)-PTR_DIFF(p,outbuf)-1, STR_TERMINATE); + p = skip_string(outbuf,sizeof(outbuf),p); + + send_mailslot(False, BROWSE_MAILSLOT, outbuf, PTR_DIFF(p,outbuf), + lp_netbios_name(), 0, + workgroup_name, 0x1e, + subrec->bcast_ip, subrec->myip, DGRAM_PORT); +} + +/******************************************************************* + We found a current master browser on one of our broadcast interfaces. +******************************************************************/ + +static void check_for_master_browser_success(struct subnet_record *subrec, + struct userdata_struct *userdata, + struct nmb_name *answer_name, + struct in_addr answer_ip, struct res_rec *rrec) +{ + unstring aname; + pull_ascii_nstring(aname, sizeof(aname), answer_name->name); + DEBUG(3,("check_for_master_browser_success: Local master browser for workgroup %s exists at \ +IP %s (just checking).\n", aname, inet_ntoa(answer_ip) )); +} + +/******************************************************************* + We failed to find a current master browser on one of our broadcast interfaces. +******************************************************************/ + +static void check_for_master_browser_fail( struct subnet_record *subrec, + struct response_record *rrec, + struct nmb_name *question_name, + int fail_code) +{ + unstring workgroup_name; + struct work_record *work; + + pull_ascii_nstring(workgroup_name,sizeof(workgroup_name),question_name->name); + + work = find_workgroup_on_subnet(subrec, workgroup_name); + if(work == NULL) { + DEBUG(0,("check_for_master_browser_fail: Unable to find workgroup %s on subnet %s.=\n", + workgroup_name, subrec->subnet_name )); + return; + } + + if (strequal(work->work_group, lp_workgroup())) { + + if (lp_local_master()) { + /* We have discovered that there is no local master + browser, and we are configured to initiate + an election that we will participate in. + */ + DEBUG(2,("check_for_master_browser_fail: Forcing election on workgroup %s subnet %s\n", + work->work_group, subrec->subnet_name )); + + /* Setting this means we will participate when the + election is run in run_elections(). */ + work->needelection = True; + } else { + /* We need to force an election, because we are configured + not to become the local master, but we still need one, + having detected that one doesn't exist. + */ + send_election_dgram(subrec, work->work_group, 0, 0, ""); + } + } +} + +/******************************************************************* + Ensure there is a local master browser for a workgroup on our + broadcast interfaces. +******************************************************************/ + +void check_master_browser_exists(time_t t) +{ + static time_t lastrun=0; + struct subnet_record *subrec; + const char *workgroup_name = lp_workgroup(); + + if (t < (lastrun + (CHECK_TIME_MST_BROWSE * 60))) + return; + + lastrun = t; + + dump_workgroups(False); + + for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) { + struct work_record *work; + + for (work = subrec->workgrouplist; work; work = work->next) { + if (strequal(work->work_group, workgroup_name) && !AM_LOCAL_MASTER_BROWSER(work)) { + /* Do a name query for the local master browser on this net. */ + query_name( subrec, work->work_group, 0x1d, + check_for_master_browser_success, + check_for_master_browser_fail, + NULL); + } + } + } +} + +/******************************************************************* + Run an election. +******************************************************************/ + +void run_elections(time_t t) +{ + static time_t lastime = 0; + + struct subnet_record *subrec; + + /* Send election packets once every 2 seconds - note */ + if (lastime && (t - lastime < 2)) { + return; + } + + lastime = t; + + for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) { + struct work_record *work; + + for (work = subrec->workgrouplist; work; work = work->next) { + if (work->RunningElection) { + /* + * We can only run an election for a workgroup if we have + * registered the WORKGROUP<1e> name, as that's the name + * we must listen to. + */ + struct nmb_name nmbname; + + make_nmb_name(&nmbname, work->work_group, 0x1e); + if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) { + DEBUG(8,("run_elections: Cannot send election packet yet as name %s not \ +yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name )); + continue; + } + + send_election_dgram(subrec, work->work_group, work->ElectionCriterion, + t - StartupTime, lp_netbios_name()); + + if (work->ElectionCount++ >= 4) { + /* Won election (4 packets were sent out uncontested. */ + DEBUG(2,("run_elections: >>> Won election for workgroup %s on subnet %s <<<\n", + work->work_group, subrec->subnet_name )); + + work->RunningElection = False; + + become_local_master_browser(subrec, work); + } + } + } + } +} + +/******************************************************************* + Determine if I win an election. +******************************************************************/ + +static bool win_election(struct work_record *work, int version, + uint32_t criterion, int timeup, const char *server_name) +{ + int mytimeup = time(NULL) - StartupTime; + uint32_t mycriterion = work->ElectionCriterion; + + /* If local master is false then never win in election broadcasts. */ + if(!lp_local_master()) { + DEBUG(3,("win_election: Losing election as local master == False\n")); + return False; + } + + DEBUG(4,("win_election: election comparison: %x:%x %x:%x %d:%d %s:%s\n", + version, ELECTION_VERSION, + criterion, mycriterion, + timeup, mytimeup, + server_name, lp_netbios_name())); + + if (version > ELECTION_VERSION) + return(False); + if (version < ELECTION_VERSION) + return(True); + + if (criterion > mycriterion) + return(False); + if (criterion < mycriterion) + return(True); + + if (timeup > mytimeup) + return(False); + if (timeup < mytimeup) + return(True); + + if (strcasecmp_m(lp_netbios_name(), server_name) > 0) + return(False); + + return(True); +} + +/******************************************************************* + Process an incoming election datagram packet. +******************************************************************/ + +void process_election(struct subnet_record *subrec, struct packet_struct *p, const char *buf) +{ + struct dgram_packet *dgram = &p->packet.dgram; + int version = CVAL(buf,0); + uint32_t criterion = IVAL(buf,1); + int timeup = IVAL(buf,5)/1000; + unstring server_name; + struct work_record *work; + unstring workgroup_name; + + pull_ascii_nstring(server_name, sizeof(server_name), buf+13); + pull_ascii_nstring(workgroup_name, sizeof(workgroup_name), dgram->dest_name.name); + + server_name[15] = 0; + + DEBUG(3,("process_election: Election request from %s at IP %s on subnet %s for workgroup %s.\n", + server_name,inet_ntoa(p->ip), subrec->subnet_name, workgroup_name )); + + DEBUG(5,("process_election: vers=%d criterion=%08x timeup=%d\n", version,criterion,timeup)); + + if(( work = find_workgroup_on_subnet(subrec, workgroup_name)) == NULL) { + DEBUG(0,("process_election: Cannot find workgroup %s on subnet %s.\n", + workgroup_name, subrec->subnet_name )); + goto done; + } + + if (!strequal(work->work_group, lp_workgroup())) { + DEBUG(3,("process_election: ignoring election request for workgroup %s on subnet %s as this \ +is not my workgroup.\n", work->work_group, subrec->subnet_name )); + goto done; + } + + if (win_election(work, version,criterion,timeup,server_name)) { + /* We take precedence over the requesting server. */ + if (!work->RunningElection) { + /* We weren't running an election - start running one. */ + + work->needelection = True; + work->ElectionCount=0; + } + + /* Note that if we were running an election for this workgroup on this + subnet already, we just ignore the server we take precedence over. */ + } else { + /* We lost. Stop participating. */ + work->needelection = False; + + if (work->RunningElection || AM_LOCAL_MASTER_BROWSER(work)) { + work->RunningElection = False; + DEBUG(3,("process_election: >>> Lost election for workgroup %s on subnet %s <<<\n", + work->work_group, subrec->subnet_name )); + if (AM_LOCAL_MASTER_BROWSER(work)) + unbecome_local_master_browser(subrec, work, False); + } + } +done: + return; +} + +/**************************************************************************** + This function looks over all the workgroups known on all the broadcast + subnets and decides if a browser election is to be run on that workgroup. + It returns True if any election packets need to be sent (this will then + be done by run_elections(). +***************************************************************************/ + +bool check_elections(void) +{ + struct subnet_record *subrec; + bool run_any_election = False; + + for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) { + struct work_record *work; + for (work = subrec->workgrouplist; work; work = work->next) { + if (work->RunningElection) { + run_any_election = work->RunningElection; + } + + /* + * Start an election if we have any chance of winning. + * Note this is a change to the previous code, that would + * only run an election if nmbd was in the potential browser + * state. We need to run elections in any state if we're told + * to. JRA. + */ + + if (work->needelection && !work->RunningElection && lp_local_master()) { + /* + * We can only run an election for a workgroup if we have + * registered the WORKGROUP<1e> name, as that's the name + * we must listen to. + */ + struct nmb_name nmbname; + + make_nmb_name(&nmbname, work->work_group, 0x1e); + if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) { + DEBUG(8,("check_elections: Cannot send election packet yet as name %s not \ +yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name )); + continue; + } + + DEBUG(3,("check_elections: >>> Starting election for workgroup %s on subnet %s <<<\n", + work->work_group, subrec->subnet_name )); + + work->ElectionCount = 0; + work->RunningElection = True; + work->needelection = False; + } + } + } + return run_any_election; +} + +/**************************************************************************** + Process a internal Samba message forcing an election. +***************************************************************************/ + +void nmbd_message_election(struct messaging_context *msg, + void *private_data, + uint32_t msg_type, + struct server_id server_id, + DATA_BLOB *data) +{ + struct subnet_record *subrec; + + for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) { + struct work_record *work; + for (work = subrec->workgrouplist; work; work = work->next) { + if (strequal(work->work_group, lp_workgroup())) { + work->needelection = True; + work->ElectionCount=0; + work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE; + } + } + } +} |