source: branches/samba-3.2.x/source/nmbd/nmbd_become_lmb.c

/* 
   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"

extern uint16 samba_nb_type; /* Samba's NetBIOS name type. */

/*******************************************************************
 Utility function to add a name to the unicast subnet, or add in
 our IP address if it already exists.
******************************************************************/

void insert_permanent_name_into_unicast( struct subnet_record *subrec, 
                                                struct nmb_name *nmbname, uint16 nb_type )
{
        unstring name;
        struct name_record *namerec;

        if((namerec = find_name_on_subnet(unicast_subnet, nmbname, FIND_SELF_NAME)) == NULL) {
                pull_ascii_nstring(name, sizeof(name), nmbname->name);
                /* The name needs to be created on the unicast subnet. */
                (void)add_name_to_subnet( unicast_subnet, name,
                                nmbname->name_type, nb_type,
                                PERMANENT_TTL, PERMANENT_NAME, 1, &subrec->myip);
        } else {
                /* The name already exists on the unicast subnet. Add our local
                IP for the given broadcast subnet to the name. */
                add_ip_to_name_record( namerec, subrec->myip);
        }
}

/*******************************************************************
 Utility function to remove a name from the unicast subnet.
******************************************************************/

static void remove_permanent_name_from_unicast( struct subnet_record *subrec,
                                                struct nmb_name *nmbname )
{
        struct name_record *namerec;

        if((namerec = find_name_on_subnet(unicast_subnet, nmbname, FIND_SELF_NAME)) != NULL) {
                /* Remove this broadcast subnet IP address from the name. */
                remove_ip_from_name_record( namerec, subrec->myip);
                if(namerec->data.num_ips == 0)
                        remove_name_from_namelist( unicast_subnet, namerec);
        }
}

/*******************************************************************
 Utility function always called to set our workgroup and server
 state back to potential browser, or none.
******************************************************************/

static void reset_workgroup_state( struct subnet_record *subrec, const char *workgroup_name,
                                   bool force_new_election )
{
        struct work_record *work;
        struct server_record *servrec;
        struct nmb_name nmbname;

        if((work = find_workgroup_on_subnet( subrec, workgroup_name)) == NULL) {
                DEBUG(0,("reset_workgroup_state: Error - cannot find workgroup %s on \
subnet %s.\n", workgroup_name, subrec->subnet_name ));
                return;
        }

        if((servrec = find_server_in_workgroup( work, global_myname())) == NULL) {
                DEBUG(0,("reset_workgroup_state: Error - cannot find server %s \
in workgroup %s on subnet %s\n",
                        global_myname(), work->work_group, subrec->subnet_name));
                work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
                return;
        }

        /* Update our server status - remove any master flag and replace
                it with the potential browser flag. */
        servrec->serv.type &= ~SV_TYPE_MASTER_BROWSER;
        servrec->serv.type |= (lp_local_master() ? SV_TYPE_POTENTIAL_BROWSER : 0);

        /* Tell the namelist writer to write out a change. */
        subrec->work_changed = True;

        /* Reset our election flags. */
        work->ElectionCriterion &= ~0x4;

        work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;

        /* Forget who the local master browser was for
                this workgroup. */

        set_workgroup_local_master_browser_name( work, "");

        /*
         * Ensure the IP address of this subnet is not registered as one
         * of the IP addresses of the WORKGROUP<1d> name on the unicast
         * subnet. This undoes what we did below when we became a local
         * master browser.
         */

        make_nmb_name(&nmbname, work->work_group, 0x1d);

        remove_permanent_name_from_unicast( subrec, &nmbname);

        if(force_new_election)
                work->needelection = True;
}

/*******************************************************************
  Unbecome the local master browser name release success function.
******************************************************************/

static void unbecome_local_master_success(struct subnet_record *subrec,
                             struct userdata_struct *userdata,
                             struct nmb_name *released_name,
                             struct in_addr released_ip)
{ 
        bool force_new_election = False;
        unstring relname;

        memcpy((char *)&force_new_election, userdata->data, sizeof(bool));

        DEBUG(3,("unbecome_local_master_success: released name %s.\n",
                nmb_namestr(released_name)));

        /* Now reset the workgroup and server state. */
        pull_ascii_nstring(relname, sizeof(relname), released_name->name);
        reset_workgroup_state( subrec, relname, force_new_election );

        if( DEBUGLVL( 0 ) ) {
                dbgtext( "*****\n\n" );
                dbgtext( "Samba name server %s ", global_myname() );
                dbgtext( "has stopped being a local master browser " );
                dbgtext( "for workgroup %s ", relname );
                dbgtext( "on subnet %s\n\n*****\n", subrec->subnet_name );
        }

}

/*******************************************************************
  Unbecome the local master browser name release fail function.
******************************************************************/

static void unbecome_local_master_fail(struct subnet_record *subrec, struct response_record *rrec,
                       struct nmb_name *fail_name)
{
        struct name_record *namerec;
        struct userdata_struct *userdata = rrec->userdata;
        bool force_new_election = False;
        unstring failname;

        memcpy((char *)&force_new_election, userdata->data, sizeof(bool));

        DEBUG(0,("unbecome_local_master_fail: failed to release name %s. \
Removing from namelist anyway.\n", nmb_namestr(fail_name)));

        /* Do it anyway. */
        namerec = find_name_on_subnet(subrec, fail_name, FIND_SELF_NAME);
        if(namerec)
                remove_name_from_namelist(subrec, namerec);

        /* Now reset the workgroup and server state. */
        pull_ascii_nstring(failname, sizeof(failname), fail_name->name);
        reset_workgroup_state( subrec, failname, force_new_election );

        if( DEBUGLVL( 0 ) ) {
                dbgtext( "*****\n\n" );
                dbgtext( "Samba name server %s ", global_myname() );
                dbgtext( "has stopped being a local master browser " );
                dbgtext( "for workgroup %s ", failname );
                dbgtext( "on subnet %s\n\n*****\n", subrec->subnet_name );
        }
}

/*******************************************************************
 Utility function to remove the WORKGROUP<1d> name.
******************************************************************/

static void release_1d_name( struct subnet_record *subrec, const char *workgroup_name,
                             bool force_new_election)
{
        struct nmb_name nmbname;
        struct name_record *namerec;

        make_nmb_name(&nmbname, workgroup_name, 0x1d);
        if((namerec = find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME))!=NULL) {
                struct userdata_struct *userdata;
                size_t size = sizeof(struct userdata_struct) + sizeof(bool);

                if((userdata = (struct userdata_struct *)SMB_MALLOC(size)) == NULL) {
                        DEBUG(0,("release_1d_name: malloc fail.\n"));
                        return;
                }

                userdata->copy_fn = NULL;
                userdata->free_fn = NULL;
                userdata->userdata_len = sizeof(bool);
                memcpy((char *)userdata->data, &force_new_election, sizeof(bool));

                release_name(subrec, namerec,
                        unbecome_local_master_success,
                        unbecome_local_master_fail,
                        userdata);

                zero_free(userdata, size);
        }
}

/*******************************************************************
 Unbecome the local master browser MSBROWSE name release success function.
******************************************************************/

static void release_msbrowse_name_success(struct subnet_record *subrec,
                      struct userdata_struct *userdata,
                      struct nmb_name *released_name,
                      struct in_addr released_ip)
{
        DEBUG(4,("release_msbrowse_name_success: Released name %s on subnet %s\n.",
                nmb_namestr(released_name), subrec->subnet_name ));

        /* Remove the permanent MSBROWSE name added into the unicast subnet. */
        remove_permanent_name_from_unicast( subrec, released_name);
}

/*******************************************************************
 Unbecome the local master browser MSBROWSE name release fail function.
******************************************************************/

static void release_msbrowse_name_fail( struct subnet_record *subrec, 
                       struct response_record *rrec,
                       struct nmb_name *fail_name)
{
        struct name_record *namerec;

        DEBUG(4,("release_msbrowse_name_fail: Failed to release name %s on subnet %s\n.",
                nmb_namestr(fail_name), subrec->subnet_name ));

        /* Release the name anyway. */
        namerec = find_name_on_subnet(subrec, fail_name, FIND_SELF_NAME);
        if(namerec)
                remove_name_from_namelist(subrec, namerec);

        /* Remove the permanent MSBROWSE name added into the unicast subnet. */
        remove_permanent_name_from_unicast( subrec, fail_name);
}

/*******************************************************************
  Unbecome the local master browser. If force_new_election is true, restart
  the election process after we've unbecome the local master.
******************************************************************/

void unbecome_local_master_browser(struct subnet_record *subrec, struct work_record *work,
                                   bool force_new_election)
{
        struct name_record *namerec;
        struct nmb_name nmbname;

  /* Sanity check. */

        DEBUG(2,("unbecome_local_master_browser: unbecoming local master for workgroup %s \
on subnet %s\n",work->work_group, subrec->subnet_name));
  
        if(find_server_in_workgroup( work, global_myname()) == NULL) {
                DEBUG(0,("unbecome_local_master_browser: Error - cannot find server %s \
in workgroup %s on subnet %s\n",
                        global_myname(), work->work_group, subrec->subnet_name));
                        work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
                return;
        }
  
        /* Set the state to unbecoming. */
        work->mst_state = MST_UNBECOMING_MASTER;

        /*
         * Release the WORKGROUP<1d> name asap to allow another machine to
         * claim it.
         */

        release_1d_name( subrec, work->work_group, force_new_election);

        /* Deregister any browser names we may have. */
        make_nmb_name(&nmbname, MSBROWSE, 0x1);
        if((namerec = find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME))!=NULL) {
                release_name(subrec, namerec,
                        release_msbrowse_name_success,
                        release_msbrowse_name_fail,
                        NULL);
        }

        /*
         * Ensure we have sent and processed these release packets
         * before returning - we don't want to process any election
         * packets before dealing with the 1d release.
         */

        retransmit_or_expire_response_records(time(NULL));
}

/****************************************************************************
  Success in registering the WORKGROUP<1d> name.
  We are now *really* a local master browser.
  ****************************************************************************/

static void become_local_master_stage2(struct subnet_record *subrec,
                                        struct userdata_struct *userdata,
                                        struct nmb_name *registered_name,
                                        uint16 nb_flags,
                                        int ttl, struct in_addr registered_ip)
{
        int i = 0;
        struct server_record *sl;
        struct work_record *work;
        struct server_record *servrec;
        unstring regname;

        pull_ascii_nstring(regname, sizeof(regname), registered_name->name);
        work = find_workgroup_on_subnet( subrec, regname);

        if(!work) {
                DEBUG(0,("become_local_master_stage2: Error - cannot find \
workgroup %s on subnet %s\n", regname, subrec->subnet_name));
                return;
        }

        if((servrec = find_server_in_workgroup( work, global_myname())) == NULL) {
                DEBUG(0,("become_local_master_stage2: Error - cannot find server %s \
in workgroup %s on subnet %s\n",
                        global_myname(), regname, subrec->subnet_name));
                        work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
                return;
        }
  
        DEBUG(3,("become_local_master_stage2: registered as master browser for workgroup %s \
on subnet %s\n", work->work_group, subrec->subnet_name));

        work->mst_state = MST_BROWSER; /* registering WORKGROUP(1d) succeeded */

        /* update our server status */
        servrec->serv.type |= SV_TYPE_MASTER_BROWSER;
        servrec->serv.type &= ~SV_TYPE_POTENTIAL_BROWSER;

        /* Tell the namelist writer to write out a change. */
        subrec->work_changed = True;

        /* Add this name to the workgroup as local master browser. */
        set_workgroup_local_master_browser_name( work, global_myname());

        /* Count the number of servers we have on our list. If it's
                less than 10 (just a heuristic) request the servers
                to announce themselves.
        */
        for( sl = work->serverlist; sl != NULL; sl = sl->next)
                i++;

        if (i < 10) {
                /* Ask all servers on our local net to announce to us. */
                broadcast_announce_request(subrec, work);
        }

        /*
         * Now we are a local master on a broadcast subnet, we need to add
         * the WORKGROUP<1d> name to the unicast subnet so that we can answer
         * unicast requests sent to this name. We can create this name directly on
         * the unicast subnet as a WINS server always returns true when registering
         * this name, and discards the registration. We use the number of IP
         * addresses registered to this name as a reference count, as we
         * remove this broadcast subnet IP address from it when we stop becoming a local
         * master browser for this broadcast subnet.
         */

        insert_permanent_name_into_unicast( subrec, registered_name, nb_flags);

        /* Reset the announce master browser timer so that we try and tell a domain
                master browser as soon as possible that we are a local master browser. */
        reset_announce_timer();

        if( DEBUGLVL( 0 ) ) {
                dbgtext( "*****\n\n" );
                dbgtext( "Samba name server %s ", global_myname() );
                dbgtext( "is now a local master browser " );
                dbgtext( "for workgroup %s ", work->work_group );
                dbgtext( "on subnet %s\n\n*****\n", subrec->subnet_name );
        }
}

/****************************************************************************
  Failed to register the WORKGROUP<1d> name.
  ****************************************************************************/

static void become_local_master_fail2(struct subnet_record *subrec,
                                      struct response_record *rrec,
                                      struct nmb_name *fail_name)
{
        unstring failname;
        struct work_record *work;

        DEBUG(0,("become_local_master_fail2: failed to register name %s on subnet %s. \
Failed to become a local master browser.\n", nmb_namestr(fail_name), subrec->subnet_name));

        pull_ascii_nstring(failname, sizeof(failname), fail_name->name);
        work = find_workgroup_on_subnet( subrec, failname);

        if(!work) {
                DEBUG(0,("become_local_master_fail2: Error - cannot find \
workgroup %s on subnet %s\n", failname, subrec->subnet_name));
                return;
        }

        /* Roll back all the way by calling unbecome_local_master_browser(). */
        unbecome_local_master_browser(subrec, work, False);
}

/****************************************************************************
  Success in registering the MSBROWSE name.
  ****************************************************************************/

static void become_local_master_stage1(struct subnet_record *subrec,
                                        struct userdata_struct *userdata,
                                        struct nmb_name *registered_name,
                                        uint16 nb_flags,
                                        int ttl, struct in_addr registered_ip)
{
        char *work_name = userdata->data;
        struct work_record *work = find_workgroup_on_subnet( subrec, work_name);

        if(!work) {
                DEBUG(0,("become_local_master_stage1: Error - cannot find \
                        %s on subnet %s\n", work_name, subrec->subnet_name));
                return;
        }

        DEBUG(3,("become_local_master_stage1: go to stage 2: register the %s<1d> name.\n",
                work->work_group));

        work->mst_state = MST_MSB; /* Registering MSBROWSE was successful. */

        /*
         * We registered the MSBROWSE name on a broadcast subnet, now need to add
         * the MSBROWSE name to the unicast subnet so that we can answer
         * unicast requests sent to this name. We create this name directly on
         * the unicast subnet.
         */

        insert_permanent_name_into_unicast( subrec, registered_name, nb_flags);

        /* Attempt to register the WORKGROUP<1d> name. */
        register_name(subrec, work->work_group,0x1d,samba_nb_type,
                become_local_master_stage2,
                become_local_master_fail2,
                NULL);
}

/****************************************************************************
  Failed to register the MSBROWSE name.
  ****************************************************************************/

static void become_local_master_fail1(struct subnet_record *subrec,
                                      struct response_record *rrec,
                                      struct nmb_name *fail_name)
{
        char *work_name = rrec->userdata->data;
        struct work_record *work = find_workgroup_on_subnet(subrec, work_name);

        if(!work) {
                DEBUG(0,("become_local_master_fail1: Error - cannot find \
workgroup %s on subnet %s\n", work_name, subrec->subnet_name));
                return;
        }

        if(find_server_in_workgroup(work, global_myname()) == NULL) {
                DEBUG(0,("become_local_master_fail1: Error - cannot find server %s \
in workgroup %s on subnet %s\n",
                        global_myname(), work->work_group, subrec->subnet_name));
                return;
        }

        reset_workgroup_state( subrec, work->work_group, False );

        DEBUG(0,("become_local_master_fail1: Failed to become a local master browser for \
workgroup %s on subnet %s. Couldn't register name %s.\n",
                work->work_group, subrec->subnet_name, nmb_namestr(fail_name)));
}

/******************************************************************
  Become the local master browser on a subnet.
  This gets called if we win an election on this subnet.

  Stage 1: mst_state was MST_POTENTIAL - go to MST_BACK register ^1^2__MSBROWSE__^2^1.
  Stage 2: mst_state was MST_BACKUP  - go to MST_MSB  and register WORKGROUP<1d>.
  Stage 3: mst_state was MST_MSB  - go to MST_BROWSER.
******************************************************************/

void become_local_master_browser(struct subnet_record *subrec, struct work_record *work)
{
        struct userdata_struct *userdata;
        size_t size = sizeof(struct userdata_struct) + sizeof(fstring) + 1;

        /* Sanity check. */
        if (!lp_local_master()) { 
                DEBUG(0,("become_local_master_browser: Samba not configured as a local master browser.\n"));
                return;
        }

        if(!AM_POTENTIAL_MASTER_BROWSER(work)) {
                DEBUG(2,("become_local_master_browser: Awaiting potential browser state. Current state is %d\n",
                        work->mst_state ));
                return;
        }

        if(find_server_in_workgroup( work, global_myname()) == NULL) {
                DEBUG(0,("become_local_master_browser: Error - cannot find server %s \
in workgroup %s on subnet %s\n",
                        global_myname(), work->work_group, subrec->subnet_name));
                return;
        }

        DEBUG(2,("become_local_master_browser: Starting to become a master browser for workgroup \
%s on subnet %s\n", work->work_group, subrec->subnet_name));
  
        DEBUG(3,("become_local_master_browser: first stage - attempt to register ^1^2__MSBROWSE__^2^1\n"));
        work->mst_state = MST_BACKUP; /* an election win was successful */

        work->ElectionCriterion |= 0x5;

        /* Tell the namelist writer to write out a change. */
        subrec->work_changed = True;

        /* Setup the userdata_struct. */
        if((userdata = (struct userdata_struct *)SMB_MALLOC(size)) == NULL) {
                DEBUG(0,("become_local_master_browser: malloc fail.\n"));
                return;
        }

        userdata->copy_fn = NULL;
        userdata->free_fn = NULL;
        userdata->userdata_len = strlen(work->work_group)+1;
        overmalloc_safe_strcpy(userdata->data, work->work_group, size - sizeof(*userdata) - 1);

        /* Register the special browser group name. */
        register_name(subrec, MSBROWSE, 0x01, samba_nb_type|NB_GROUP,
                become_local_master_stage1,
                become_local_master_fail1,
                userdata);

        zero_free(userdata, size);
}

/***************************************************************
 Utility function to set the local master browser name. Does
 some sanity checking as old versions of Samba seem to sometimes
 say that the master browser name for a workgroup is the same
 as the workgroup name.
****************************************************************/

void set_workgroup_local_master_browser_name( struct work_record *work, const char *newname)
{
        DEBUG(5,("set_workgroup_local_master_browser_name: setting local master name to '%s' \
for workgroup %s.\n", newname, work->work_group ));

#if 0
  /*
   * Apparently some sites use the workgroup name as the local
   * master browser name. Arrrrggghhhhh ! (JRA).
   */
  if(strequal( work->work_group, newname))
  {
    DEBUG(5, ("set_workgroup_local_master_browser_name: Refusing to set \
local_master_browser_name for workgroup %s to workgroup name.\n",
         work->work_group ));
    return;
  }
#endif

        unstrcpy(work->local_master_browser_name, newname);
}