/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   NBT netbios routines and daemon - version 2
   Copyright (C) Andrew Tridgell 1994-1995
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   
   Revision History:

   14 jan 96: lkcl@pires.co.uk
   added multiple workgroup domain master support

*/

#include "includes.h"
#include "smb.h"

extern int ClientNMB;

extern int DEBUGLEVEL;

extern struct in_addr wins_ip;

/* this is our browse master/backup cache database */
static struct browse_cache_record *browserlist = NULL;


/***************************************************************************
  add a browser into the list
  **************************************************************************/
static void add_browse_cache(struct browse_cache_record *b)
{
  struct browse_cache_record *b2;

  if (!browserlist)
    {
      browserlist = b;
      b->prev = NULL;
      b->next = NULL;
      return;
    }
  
  for (b2 = browserlist; b2->next; b2 = b2->next) ;
  
  b2->next = b;
  b->next = NULL;
  b->prev = b2;
}


/*******************************************************************
  remove old browse entries
  ******************************************************************/
void expire_browse_cache(time_t t)
{
  struct browse_cache_record *b;
  struct browse_cache_record *nextb;
  
  /* expire old entries in the serverlist */
  for (b = browserlist; b; b = nextb)
    {
      if (b->synced && b->sync_time < t)
	{
	  DEBUG(3,("Removing dead cached browser %s\n",b->name));
	  nextb = b->next;
	  
	  if (b->prev) b->prev->next = b->next;
	  if (b->next) b->next->prev = b->prev;
	  
	  if (browserlist == b) browserlist = b->next; 
	  
	  free(b);
	}
      else
	{
	  nextb = b->next;
	}
    }
}

/****************************************************************************
  add a browser entry
  ****************************************************************************/
struct browse_cache_record *add_browser_entry(char *name, int type, char *wg,
					      time_t ttl, struct in_addr ip, BOOL local)
{
  BOOL newentry=False;
  
  struct browse_cache_record *b;

  /* search for the entry: if it's already in the cache, update that entry */
  for (b = browserlist; b; b = b->next)
    {
      if (ip_equal(ip,b->ip) && strequal(b->group, wg)) break;
    }
  
  if (b && b->synced)
    {
      /* entries get left in the cache for a while. this stops sync'ing too
	 often if the network is large */
      DEBUG(4, ("browser %s %s %s already sync'd at time %d\n",
		b->name, b->group, inet_ntoa(b->ip), b->sync_time));
      return NULL;
    }
  
  if (!b)
    {
      newentry = True;
      b = (struct browse_cache_record *)malloc(sizeof(*b));
      
      if (!b) return(NULL);
      
      bzero((char *)b,sizeof(*b));
    }
  
  /* update the entry */
  ttl = time(NULL)+ttl;
  
  StrnCpy(b->name ,name,sizeof(b->name )-1);
  StrnCpy(b->group,wg  ,sizeof(b->group)-1);
  strupper(b->name);
  strupper(b->group);
  
  b->ip     = ip;
  b->type   = type;
  b->local  = local; /* local server list sync or complete sync required */
  
  if (newentry || ttl < b->sync_time) 
    b->sync_time = ttl;
  
  if (newentry)
    {
      b->synced = False;
      add_browse_cache(b);
      
      DEBUG(3,("Added cache entry %s %s(%2x) %s ttl %d\n",
	       wg, name, type, inet_ntoa(ip),ttl));
    }
  else
    {
      DEBUG(3,("Updated cache entry %s %s(%2x) %s ttl %d\n",
	       wg, name, type, inet_ntoa(ip),ttl));
    }
  
  return(b);
}


/****************************************************************************
find a server responsible for a workgroup, and sync browse lists
**************************************************************************/
static void start_sync_browse_entry(struct browse_cache_record *b)
{                     
  struct subnet_record *d;
  struct work_record *work;

  /* Look for the workgroup first on the local subnet. If this
     fails try WINS - we may need to sync with the domain master,
     or we may be the domain master and need to sync with subnet
     masters.
  */

  if (!(d = find_subnet_all(b->ip))) {
    DEBUG(0, ("start_sync_browse_entry: failed to get a \
subnet for a browse cache entry workgroup %s, server %s\n", 
                  b->group, b->name));
    return;
  }

  if (!(work = find_workgroupstruct(d, b->group, False))) {
      DEBUG(0, ("start_sync_browse_entry: failed to get a \
workgroup for a browse cache entry workgroup %s, server %s\n", 
		b->group, b->name));
      return;
  }

  /* only sync if we are a subnet master or domain master - but
     we sync if we are a master for this workgroup on *any* 
     of our interfaces. */
  if (AM_MASTER(work) || AM_DOMMST(work) || AM_ANY_MASTER(work)) {

    DEBUG(4, ("start_sync_browse_entry: Initiating %s sync with %s<0x20>, \
workgroup %s\n",
               b->local ? "local" : "remote", b->name, b->group));

    /* first check whether the server we intend to sync with exists. if it
       doesn't, the server must have died. o dear. */

    /* see response_netbios_packet() or expire_netbios_response_entries() */
    /* We cheat here by using the my_comment field of the response_record 
       struct as the workgroup name we are going to do the sync for. 
       This is because the reply packet doesn't include the workgroup, but 
       we need it when the reply comes back.
    */
    queue_netbios_packet(d,ClientNMB,NMB_QUERY,
			 b->local?NAME_QUERY_SYNC_LOCAL:NAME_QUERY_SYNC_REMOTE,
			 b->name,0x20,0,0,0,NULL,b->group,
			 False,False,b->ip,b->ip);
  }

  b->synced = True;
}


/****************************************************************************
  search through browser list for an entry to sync with
  **************************************************************************/
void do_browser_lists(time_t t)
{
  struct browse_cache_record *b;
  static time_t last = 0;
  
  if (t-last < 20) 
   {
     DEBUG(9,("do_browser_lists: returning due to t(%d) - last(%d) < 20\n",
             t, last));
     return; /* don't do too many of these at once! */
                           /* XXXX equally this period should not be too long
                              the server may die in the intervening gap */
   } 
  last = t;
  
  /* pick any entry in the list, preferably one whose time is up */
  for (b = browserlist; b && b->next; b = b->next)
    {
      if (b->sync_time < t && b->synced == False) break;
    }
  
  if (b && !b->synced)
  {
    /* sync with the selected entry then remove some dead entries */
    DEBUG(4,("do_browser_lists: Initiating sync with %s, workgroup %s\n",
              b->name, b->group));
    start_sync_browse_entry(b);
    expire_browse_cache(t - 60);
  }
  else
  {
    DEBUG(9, ("do_browser_lists: no entries to sync.\n"));
  }

}