Correctly handle asynchronously re-established server links

Don't try to establish an outgoing server link after DNS lookup when this
server re-connected on its own in the meantime.
In addition, log a warning message if we try to update the connection
index of an already connected server structure -- and ignore it.

Up to now, both behaviour could lead to a race when the remote server
connects to this daemon while it still prepares the outgoing connection:

 - The local server prepares the new outgoing connection ...
 - in the meantime the remote server becomes connected and registered.
 - Now the new outgoing connection overwrites the (correct) socket handle,
 - then the 2nd connection becomes disconnected: "already registered",
 - and the 1st connection becomes unhandled ("gets lost") because the
   configuration structure is reset because of the wrong socket handle.

This patch hopefully fixes all these problems.

diff --git a/src/ngircd/conf.c b/src/ngircd/conf.c
index 54269009d1ee433bb537fa1c4ef140f34ea2cb57..f274eb826391dd3c0975383f77c48963a64ef4c1 100644 (file)
--- a/src/ngircd/conf.c
+++ b/src/ngircd/conf.c
@@ -1,6 +1,6 @@
 /*
  * ngIRCd -- The Next Generation IRC Daemon
- * Copyright (c)2001-2011 Alexander Barton (alex@barton.de) and Contributors.
+ * Copyright (c)2001-2012 Alexander Barton (alex@barton.de) and Contributors.
  *
  * 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
@@ -492,6 +492,14 @@ Conf_SetServer( int ConfServer, CONN_ID Idx )
        assert( ConfServer > NONE );
        assert( Idx > NONE );
 
+       if (Conf_Server[ConfServer].conn_id > NONE &&
+           Conf_Server[ConfServer].conn_id != Idx) {
+               Log(LOG_ALERT,
+                       "Trying to update connection index for already registered server \"%s\": %d/%d - ignored.",
+                       Conf_Server[ConfServer].name,
+                       Conf_Server[ConfServer].conn_id, Idx);
+               return;
+       }
        Conf_Server[ConfServer].conn_id = Idx;
 }
 

diff --git a/src/ngircd/conn.c b/src/ngircd/conn.c
index 09f726ca2bf91016d54a8d2b2c7c10029943fa68..06236fd43e2ab1269e91e1065efa11786da0ed40 100644 (file)
--- a/src/ngircd/conn.c
+++ b/src/ngircd/conn.c
@@ -1,6 +1,6 @@
 /*
  * ngIRCd -- The Next Generation IRC Daemon
- * Copyright (c)2001-2011 Alexander Barton (alex@barton.de) and Contributors.
+ * Copyright (c)2001-2012 Alexander Barton (alex@barton.de) and Contributors.
  *
  * 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
@@ -1935,6 +1935,14 @@ New_Server( int Server , ng_ipaddr_t *dest)
 
        assert( Server > NONE );
 
+       /* Make sure that the remote server hasn't re-linked to this server
+        * asynchronously on its own */
+       if (Conf_Server[Server].conn_id > NONE) {
+               Log(LOG_INFO,
+                       "Connection to \"%s\" meanwhile re-established, aborting preparation.");
+               return;
+       }
+
        if (!ng_ipaddr_tostr_r(dest, ip_str)) {
                Log(LOG_WARNING, "New_Server: Could not convert IP to string");
                return;
@@ -2008,7 +2016,7 @@ New_Server( int Server , ng_ipaddr_t *dest)
        Client_SetToken( c, TOKEN_OUTBOUND );
 
        /* Register connection */
-       Conf_Server[Server].conn_id = new_sock;
+       Conf_SetServer(Server, new_sock);
        My_Connections[new_sock].sock = new_sock;
        My_Connections[new_sock].addr = *dest;
        My_Connections[new_sock].client = c;