source: branches/samba-3.3.x/source/smbd/conn.c

/* 
   Unix SMB/CIFS implementation.
   Manage connections_struct structures
   Copyright (C) Andrew Tridgell 1998
   Copyright (C) Alexander Bokovoy 2002
   
   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"

/* The connections bitmap is expanded in increments of BITMAP_BLOCK_SZ. The
 * maximum size of the bitmap is the largest positive integer, but you will hit
 * the "max connections" limit, looong before that.
 */
#define BITMAP_BLOCK_SZ 128

static connection_struct *Connections;

/* number of open connections */
static struct bitmap *bmap;
static int num_open;

/****************************************************************************
init the conn structures
****************************************************************************/
void conn_init(void)
{
        bmap = bitmap_allocate(BITMAP_BLOCK_SZ);
}

/****************************************************************************
return the number of open connections
****************************************************************************/
int conn_num_open(void)
{
        return num_open;
}


/****************************************************************************
check if a snum is in use
****************************************************************************/
bool conn_snum_used(int snum)
{
        connection_struct *conn;
        for (conn=Connections;conn;conn=conn->next) {
                if (conn->params->service == snum) {
                        return(True);
                }
        }
        return(False);
}

/****************************************************************************
 Find a conn given a cnum.
****************************************************************************/

connection_struct *conn_find(unsigned cnum)
{
        int count=0;
        connection_struct *conn;

        for (conn=Connections;conn;conn=conn->next,count++) {
                if (conn->cnum == cnum) {
                        if (count > 10) {
                                DLIST_PROMOTE(Connections, conn);
                        }
                        return conn;
                }
        }

        return NULL;
}

/****************************************************************************
  find first available connection slot, starting from a random position.
The randomisation stops problems with the server dieing and clients
thinking the server is still available.
****************************************************************************/
connection_struct *conn_new(void)
{
        connection_struct *conn;
        int i;
        int find_offset = 1;

find_again:
        i = bitmap_find(bmap, find_offset);
        
        if (i == -1) {
                /* Expand the connections bitmap. */
                int             oldsz = bmap->n;
                int             newsz = bmap->n + BITMAP_BLOCK_SZ;
                struct bitmap * nbmap;

                if (newsz <= oldsz) {
                        /* Integer wrap. */
                        DEBUG(0,("ERROR! Out of connection structures\n"));
                        return NULL;
                }

                DEBUG(4,("resizing connections bitmap from %d to %d\n",
                        oldsz, newsz));

                nbmap = bitmap_allocate(newsz);
                if (!nbmap) {
                        DEBUG(0,("ERROR! malloc fail.\n"));
                        return NULL;
                }

                bitmap_copy(nbmap, bmap);
                bitmap_free(bmap);

                bmap = nbmap;
                find_offset = oldsz; /* Start next search in the new portion. */

                goto find_again;
        }

        /* The bitmap position is used below as the connection number
         * conn->cnum). This ends up as the TID field in the SMB header,
         * which is limited to 16 bits (we skip 0xffff which is the
         * NULL TID).
         */
        if (i > 65534) {
                DEBUG(0, ("Maximum connection limit reached\n"));
                return NULL;
        }

        if (!(conn=TALLOC_ZERO_P(NULL, connection_struct)) ||
            !(conn->params = TALLOC_P(conn, struct share_params))) {
                DEBUG(0,("TALLOC_ZERO() failed!\n"));
                TALLOC_FREE(conn);
                return NULL;
        }
        conn->cnum = i;
        conn->force_group_gid = (gid_t)-1;

        bitmap_set(bmap, i);

        num_open++;

        string_set(&conn->dirpath,"");
        string_set(&conn->connectpath,"");
        string_set(&conn->origpath,"");
        
        DLIST_ADD(Connections, conn);

        return conn;
}

/****************************************************************************
 Close all conn structures.
return true if any were closed
****************************************************************************/
bool conn_close_all(void)
{
        connection_struct *conn, *next;
        bool ret = false;
        for (conn=Connections;conn;conn=next) {
                next=conn->next;
                set_current_service(conn, 0, True);
                close_cnum(conn, conn->vuid);
                ret = true;
        }
        return ret;
}

/****************************************************************************
 Idle inactive connections.
****************************************************************************/

bool conn_idle_all(time_t t)
{
        int deadtime = lp_deadtime()*60;
        pipes_struct *plist = NULL;
        connection_struct *conn;

        if (deadtime <= 0)
                deadtime = DEFAULT_SMBD_TIMEOUT;

        for (conn=Connections;conn;conn=conn->next) {

                time_t age = t - conn->lastused;

                /* Update if connection wasn't idle. */
                if (conn->lastused != conn->lastused_count) {
                        conn->lastused = t;
                        conn->lastused_count = t;
                }

                /* close dirptrs on connections that are idle */
                if (age > DPTR_IDLE_TIMEOUT) {
                        dptr_idlecnum(conn);
                }

                if (conn->num_files_open > 0 || age < deadtime) {
                        return False;
                }
        }

        /*
         * Check all pipes for any open handles. We cannot
         * idle with a handle open.
         */

        for (plist = get_first_internal_pipe(); plist;
             plist = get_next_internal_pipe(plist)) {
                if (plist->pipe_handles && plist->pipe_handles->count) {
                        return False;
                }
        }
        
        return True;
}

/****************************************************************************
 Clear a vuid out of the validity cache, and as the 'owner' of a connection.
****************************************************************************/

void conn_clear_vuid_caches(uint16_t vuid)
{
        connection_struct *conn;

        for (conn=Connections;conn;conn=conn->next) {
                if (conn->vuid == vuid) {
                        conn->vuid = UID_FIELD_INVALID;
                }
                conn_clear_vuid_cache(conn, vuid);
        }
}

/****************************************************************************
 Free a conn structure - internal part.
****************************************************************************/

void conn_free_internal(connection_struct *conn)
{
        vfs_handle_struct *handle = NULL, *thandle = NULL;
        struct trans_state *state = NULL;

        /* Free vfs_connection_struct */
        handle = conn->vfs_handles;
        while(handle) {
                thandle = handle->next;
                DLIST_REMOVE(conn->vfs_handles, handle);
                if (handle->free_data)
                        handle->free_data(&handle->data);
                handle = thandle;
        }

        /* Free any pending transactions stored on this conn. */
        for (state = conn->pending_trans; state; state = state->next) {
                /* state->setup is a talloc child of state. */
                SAFE_FREE(state->param);
                SAFE_FREE(state->data);
        }

        free_namearray(conn->veto_list);
        free_namearray(conn->hide_list);
        free_namearray(conn->veto_oplock_list);
        free_namearray(conn->aio_write_behind_list);
        
        string_free(&conn->dirpath);
        string_free(&conn->connectpath);
        string_free(&conn->origpath);

        ZERO_STRUCTP(conn);
        talloc_destroy(conn);
}

/****************************************************************************
 Free a conn structure.
****************************************************************************/

void conn_free(connection_struct *conn)
{
        DLIST_REMOVE(Connections, conn);

        bitmap_clear(bmap, conn->cnum);

        SMB_ASSERT(num_open > 0);
        num_open--;

        conn_free_internal(conn);
}
 
/****************************************************************************
receive a smbcontrol message to forcibly unmount a share
the message contains just a share name and all instances of that
share are unmounted
the special sharename '*' forces unmount of all shares
****************************************************************************/
void msg_force_tdis(struct messaging_context *msg,
                    void *private_data,
                    uint32_t msg_type,
                    struct server_id server_id,
                    DATA_BLOB *data)
{
        connection_struct *conn, *next;
        fstring sharename;

        fstrcpy(sharename, (const char *)data->data);

        if (strcmp(sharename, "*") == 0) {
                DEBUG(1,("Forcing close of all shares\n"));
                conn_close_all();
                return;
        }

        for (conn=Connections;conn;conn=next) {
                next=conn->next;
                if (strequal(lp_servicename(SNUM(conn)), sharename)) {
                        DEBUG(1,("Forcing close of share %s cnum=%d\n",
                                 sharename, conn->cnum));
                        close_cnum(conn, (uint16)-1);
                }
        }
}