source/namebrowse.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    NBT netbios routines and daemon - version 2
   5    Copyright (C) Andrew Tridgell 1994-1995
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21    Revision History:
  22
  23    14 jan 96: lkcl@pires.co.uk
  24    added multiple workgroup domain master support
  25
  26 */
  27
  28 #include "includes.h"
  29 #include "smb.h"
  30
  31 extern int ClientNMB;
  32
  33 extern int DEBUGLEVEL;
  34
  35 /* this is our browse master/backup cache database */
  36 static struct browse_cache_record *browserlist = NULL;
  37
  38
  39 /***************************************************************************
  40   add a browser into the list
  41   **************************************************************************/
  42 static void add_browse_cache(struct browse_cache_record *b)
  43 {
  44   struct browse_cache_record *b2;
  45
  46   if (!browserlist)
  47     {
  48       browserlist = b;
  49       b->prev = NULL;
  50       b->next = NULL;
  51       return;
  52     }
  53
  54   for (b2 = browserlist; b2->next; b2 = b2->next) ;
  55
  56   b2->next = b;
  57   b->next = NULL;
  58   b->prev = b2;
  59 }
  60
  61
  62 /*******************************************************************
  63   remove old browse entries
  64   ******************************************************************/
  65 void expire_browse_cache(time_t t)
  66 {
  67   struct browse_cache_record *b;
  68   struct browse_cache_record *nextb;
  69
  70   /* expire old entries in the serverlist */
  71   for (b = browserlist; b; b = nextb)
  72     {
  73       if (b->synced && b->sync_time < t)
  74         {
  75           DEBUG(3,("Removing dead cached browser %s\n",b->name));
  76           nextb = b->next;
  77
  78           if (b->prev) b->prev->next = b->next;
  79           if (b->next) b->next->prev = b->prev;
  80
  81           if (browserlist == b) browserlist = b->next;
  82
  83           free(b);
  84         }
  85       else
  86         {
  87           nextb = b->next;
  88         }
  89     }
  90 }
  91
  92
  93 /****************************************************************************
  94   add a browser entry
  95   ****************************************************************************/
  96 struct browse_cache_record *add_browser_entry(char *name, int type, char *wg,
  97                                               time_t ttl, struct in_addr ip, BOOL local)
  98 {
  99   BOOL newentry=False;
 100
 101   struct browse_cache_record *b;
 102
 103   /* search for the entry: if it's already in the cache, update that entry */
 104   for (b = browserlist; b; b = b->next)
 105     {
 106       if (ip_equal(ip,b->ip) && strequal(b->group, wg)) break;
 107     }
 108
 109   if (b && b->synced)
 110     {
 111       /* entries get left in the cache for a while. this stops sync'ing too
 112          often if the network is large */
 113       DEBUG(4, ("browser %s %s %s already sync'd at time %d\n",
 114                 b->name, b->group, inet_ntoa(b->ip), b->sync_time));
 115       return NULL;
 116     }
 117
 118   if (!b)
 119     {
 120       newentry = True;
 121       b = (struct browse_cache_record *)malloc(sizeof(*b));
 122
 123       if (!b) return(NULL);
 124
 125       bzero((char *)b,sizeof(*b));
 126     }
 127
 128   /* update the entry */
 129   ttl = time(NULL)+ttl;
 130
 131   StrnCpy(b->name ,name,sizeof(b->name )-1);
 132   StrnCpy(b->group,wg  ,sizeof(b->group)-1);
 133   strupper(b->name);
 134   strupper(b->group);
 135
 136   b->ip     = ip;
 137   b->type   = type;
 138   b->local  = local; /* local server list sync or complete sync required */
 139
 140   if (newentry || ttl < b->sync_time)
 141     b->sync_time = ttl;
 142
 143   if (newentry)
 144     {
 145       b->synced = False;
 146       add_browse_cache(b);
 147
 148       DEBUG(3,("Added cache entry %s %s(%2x) %s ttl %d\n",
 149                wg, name, type, inet_ntoa(ip),ttl));
 150     }
 151   else
 152     {
 153       DEBUG(3,("Updated cache entry %s %s(%2x) %s ttl %d\n",
 154                wg, name, type, inet_ntoa(ip),ttl));
 155     }
 156
 157   return(b);
 158 }
 159
 160
 161 /****************************************************************************
 162 find a server responsible for a workgroup, and sync browse lists
 163 **************************************************************************/
 164 static void start_sync_browse_entry(struct browse_cache_record *b)
 165 {
 166   struct subnet_record *d;
 167   struct work_record *work;
 168
 169   if (!(d = find_subnet(b->ip))) return;
 170
 171   if (!(work = find_workgroupstruct(d, b->group, False))) return;
 172
 173   /* only sync if we are the master */
 174   if (AM_MASTER(work)) {
 175
 176       /* first check whether the group we intend to sync with exists. if it
 177          doesn't, the server must have died. o dear. */
 178
 179       /* see response_netbios_packet() or expire_netbios_response_entries() */
 180       queue_netbios_packet(d,ClientNMB,NMB_QUERY,
 181                        b->local?NAME_QUERY_SYNC_LOCAL:NAME_QUERY_SYNC_REMOTE,
 182                                            b->group,0x20,0,0,0,NULL,NULL,
 183                                            False,False,b->ip,b->ip);
 184   }
 185
 186   b->synced = True;
 187 }
 188
 189
 190 /****************************************************************************
 191   search through browser list for an entry to sync with
 192   **************************************************************************/
 193 void do_browser_lists(void)
 194 {
 195   struct browse_cache_record *b;
 196   static time_t last = 0;
 197   time_t t = time(NULL);
 198
 199   if (t-last < 20) return; /* don't do too many of these at once! */
 200                            /* XXXX equally this period should not be too long
 201                               the server may die in the intervening gap */
 202
 203   last = t;
 204
 205   /* pick any entry in the list, preferably one whose time is up */
 206   for (b = browserlist; b && b->next; b = b->next)
 207     {
 208       if (b->sync_time < t && b->synced == False) break;
 209     }
 210
 211   if (b && !b->synced)
 212   {
 213     /* sync with the selected entry then remove some dead entries */
 214     start_sync_browse_entry(b);
 215     expire_browse_cache(t - 60);
 216   }
 217
 218 }
 219