r11909: Implement 'reset on zero vc'. This kills other connections when a session

setup comes in with the vc (virtual connection) field set to zero. This is
done by Windows, probably you can tweak that by some registry key.

	This boolean option controls whether an incoming session setup
	should kill other connections coming from the same IP. This matches
        the default Windows 2003 behaviour.

	Setting this parameter to yes becomes necessary when you have a flaky
	network and windows decides to reconnect while the old connection
	still has files with share modes open. These files become inaccessible
	over the new connection.

	The client sends a zero VC on the new connection, and Windows 2003
	kills all other connections coming from the same IP. This way the
	locked files are accessible again.

	Please be aware that enabling this option will kill connections behind
	a masquerading router.

Volker
(This used to be commit 5629ca16235f0aa21fea3afd9e414309e4e1374e)

3 files changed, 32 insertions, 1 deletions

diff --git a/source3/param/loadparm.c b/source3/param/loadparm.c
index f45d8cf952..86a5353dca 100644
--- a/source3/param/loadparm.c
+++ b/source3/param/loadparm.c
@@ -301,6 +301,7 @@ typedef struct
 	int name_cache_timeout;
 	int client_signing;
 	int server_signing;
+	BOOL bResetOnZeroVC;
 	param_opt_struct *param_opt;
 }
 global;
@@ -951,6 +952,7 @@ static struct parm_struct parm_table[] = {
 	{"read raw", P_BOOL, P_GLOBAL, &Globals.bReadRaw, NULL, NULL, FLAG_ADVANCED}, 
 	{"write raw", P_BOOL, P_GLOBAL, &Globals.bWriteRaw, NULL, NULL, FLAG_ADVANCED}, 
 	{"disable netbios", P_BOOL, P_GLOBAL, &Globals.bDisableNetbios, NULL, NULL, FLAG_ADVANCED}, 
+	{"reset on zero vc", P_BOOL, P_GLOBAL, &Globals.bResetOnZeroVC, NULL, NULL, FLAG_ADVANCED}, 
 
 	{"acl compatibility", P_STRING, P_GLOBAL, &Globals.szAclCompat, handle_acl_compatibility,  NULL, FLAG_ADVANCED | FLAG_SHARE | FLAG_GLOBAL}, 
 	{"defer sharing violations", P_BOOL, P_GLOBAL, &Globals.bDeferSharingViolations, NULL, NULL, FLAG_ADVANCED | FLAG_GLOBAL},
@@ -1522,6 +1524,7 @@ static void init_globals(void)
 	Globals.bUseMmap = True;
 #endif
 	Globals.bUnixExtensions = True;
+	Globals.bResetOnZeroVC = False;
 
 	/* hostname lookups can be very expensive and are broken on
 	   a large number of sites (tridge) */
@@ -1809,6 +1812,7 @@ FN_GLOBAL_STRING(lp_delete_share_cmd, &Globals.szDeleteShareCommand)
 FN_GLOBAL_LIST(lp_eventlog_list, &Globals.szEventLogs)
 
 FN_GLOBAL_BOOL(lp_disable_netbios, &Globals.bDisableNetbios)
+FN_GLOBAL_BOOL(lp_reset_on_zero_vc, &Globals.bResetOnZeroVC)
 FN_GLOBAL_BOOL(lp_ms_add_printer_wizard, &Globals.bMsAddPrinterWizard)
 FN_GLOBAL_BOOL(lp_dns_proxy, &Globals.bDNSproxy)
 FN_GLOBAL_BOOL(lp_wins_support, &Globals.bWINSsupport)
diff --git a/source3/smbd/session.c b/source3/smbd/session.c
index 9a9a0d90b2..27f760a088 100644
--- a/source3/smbd/session.c
+++ b/source3/smbd/session.c
@@ -198,7 +198,8 @@ void session_yield(user_struct *vuser)
 	tdb_delete(tdb, key);
 }
 
-static BOOL session_traverse(int (*fn)(TDB_CONTEXT *, TDB_DATA, TDB_DATA, void *), void *state)
+BOOL session_traverse(int (*fn)(TDB_CONTEXT *, TDB_DATA, TDB_DATA, void *),
+		      void *state)
 {
 	if (!session_init()) {
 		DEBUG(3, ("No tdb opened\n"));
diff --git a/source3/smbd/sesssetup.c b/source3/smbd/sesssetup.c
index 8aa046b85a..a22a575c76 100644
--- a/source3/smbd/sesssetup.c
+++ b/source3/smbd/sesssetup.c
@@ -744,6 +744,29 @@ static int reply_sesssetup_and_X_spnego(connection_struct *conn, char *inbuf,
  a new session setup with VC==0 is ignored.
 ****************************************************************************/
 
+static int shutdown_other_smbds(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
+				void *p)
+{
+	struct sessionid *sessionid = (struct sessionid *)dbuf.dptr;
+	const char *ip = (const char *)p;
+
+	if (!process_exists(pid_to_procid(sessionid->pid))) {
+		return 0;
+	}
+
+	if (sessionid->pid == sys_getpid()) {
+		return 0;
+	}
+
+	if (strcmp(ip, sessionid->ip_addr) != 0) {
+		return 0;
+	}
+
+	message_send_pid(pid_to_procid(sessionid->pid), MSG_SHUTDOWN,
+			 NULL, 0, True);
+	return 0;
+}
+
 static void setup_new_vc_session(void)
 {
 	DEBUG(2,("setup_new_vc_session: New VC == 0, if NT4.x compatible we would close all old resources.\n"));
@@ -751,6 +774,9 @@ static void setup_new_vc_session(void)
 	conn_close_all();
 	invalidate_all_vuids();
 #endif
+	if (lp_reset_on_zero_vc()) {
+		session_traverse(shutdown_other_smbds, client_addr());
+	}
 }
 
 /****************************************************************************