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connection.c

/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   connection claim routines
   Copyright (C) Andrew Tridgell 1998
   
   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.
*/

#include "includes.h"


extern fstring remote_machine;
static TDB_CONTEXT *tdb;

/****************************************************************************
 Return the connection tdb context (used for message send all).
****************************************************************************/

TDB_CONTEXT *conn_tdb_ctx(void)
{
      return tdb;
}

/****************************************************************************
 Delete a connection record.
****************************************************************************/

BOOL yield_connection(connection_struct *conn,const char *name)
{
      struct connections_key key;
      TDB_KEY kbuf;

      if (!tdb) return False;

      DEBUG(3,("Yielding connection to %s\n",name));

      ZERO_STRUCT(key);
      key.pid = sys_getpid();
      key.cnum = conn?conn->cnum:-1;
      dos_to_unix(key.name, name);  /* Convert key to unix-codepage */

      kbuf.dptr = (char *)&key;
      kbuf.dsize = sizeof(key);

      if (tdb_delete(tdb, kbuf) != 0) {
            int dbg_lvl = (!conn && (tdb_error(tdb) == TDB_ERR_NOEXIST)) ? 3 : 0;
            DEBUG(dbg_lvl,("yield_connection: tdb_delete for name %s failed with error %s.\n",
                  name, tdb_errorstr(tdb) ));
            return (False);
      }

      return(True);
}

struct count_stat {
      pid_t mypid;
      int curr_connections;
      char *name;
      BOOL Clear;
};

/****************************************************************************
 Count the entries belonging to a service in the connection db.
****************************************************************************/

static int count_fn( TDB_CONTEXT *the_tdb, TDB_KEY kbuf, TDB_DATA dbuf, void *udp)
{
      struct connections_data crec;
      struct count_stat *cs = (struct count_stat *)udp;
 
      if (dbuf.dsize != sizeof(crec))
            return 0;

      memcpy(&crec, dbuf.dptr, sizeof(crec));
 
      if (crec.cnum == -1)
            return 0;

      /* If the pid was not found delete the entry from connections.tdb */

      if (cs->Clear && !process_exists(crec.pid) && (errno == ESRCH)) {
            DEBUG(2,("pid %u doesn't exist - deleting connections %d [%s]\n",
                  (unsigned int)crec.pid, crec.cnum, crec.name));
            if (tdb_delete(the_tdb, kbuf) != 0)
                  DEBUG(0,("count_fn: tdb_delete failed with error %s\n", tdb_errorstr(tdb) ));
            return 0;
      }

      if (strequal(crec.name, cs->name))
            cs->curr_connections++;

      return 0;
}

/****************************************************************************
 Claim an entry in the connections database.
****************************************************************************/

BOOL claim_connection(connection_struct *conn,const char *name,int max_connections,BOOL Clear)
{
      struct connections_key key;
      struct connections_data crec;
      TDB_KEY kbuf;
      TDB_DATA dbuf;

      if (!tdb) {
            tdb = tdb_open_log(lock_path("connections.tdb"), 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT, 
                         O_RDWR | O_CREAT, 0644);
      }
      if (!tdb)
            return False;

      /*
       * Enforce the max connections parameter.
       */

      if (max_connections > 0) {
            struct count_stat cs;

            cs.mypid = sys_getpid();
            cs.curr_connections = 0;
            cs.name = lp_servicename(SNUM(conn));
            cs.Clear = Clear;

            /*
             * This has a race condition, but locking the chain before hand is worse
             * as it leads to deadlock.
             */

            if (tdb_traverse(tdb, count_fn, &cs) == -1) {
                  DEBUG(0,("claim_connection: traverse of connections.tdb failed with error %s.\n",
                        tdb_errorstr(tdb) ));
                  return False;
            }

            if (cs.curr_connections >= max_connections) {
                  DEBUG(1,("claim_connection: Max connections (%d) exceeded for %s\n",
                        max_connections, name ));
                  return False;
            }
      }

      DEBUG(5,("claiming %s %d\n",name,max_connections));

      ZERO_STRUCT(key);
      key.pid = sys_getpid();
      key.cnum = conn?conn->cnum:-1;
      dos_to_unix(key.name, name);  /* Convert key to unix-codepage */

      kbuf.dptr = (char *)&key;
      kbuf.dsize = sizeof(key);

      /* fill in the crec */
      ZERO_STRUCT(crec);
      crec.magic = 0x280267;
      crec.pid = sys_getpid();
      crec.cnum = conn?conn->cnum:-1;
      if (conn) {
            crec.uid = conn->uid;
            crec.gid = conn->gid;
            StrnCpy(crec.name,
                  lp_servicename(SNUM(conn)),sizeof(crec.name)-1);
      }
      crec.start = time(NULL);
      
      StrnCpy(crec.machine,remote_machine,sizeof(crec.machine)-1);
      StrnCpy(crec.addr,conn?conn->client_address:client_addr(),sizeof(crec.addr)-1);

      dbuf.dptr = (char *)&crec;
      dbuf.dsize = sizeof(crec);

      if (tdb_store(tdb, kbuf, dbuf, TDB_REPLACE) != 0) {
            DEBUG(0,("claim_connection: tdb_store failed with error %s.\n",
                  tdb_errorstr(tdb) ));
            return False;
      }

      return True;
}

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