commit eb4f9eac0c35071838c9367f1204db0d0b98ad2e
from: Alexander Barton <alex@barton.de>
date: Mon Oct 29 10:33:49 2012 UTC

Don't accept connections for servers already beeing linked

If two servers try to link each other, there was a time frame that
could result in one connection overwriting the other, e. g. the incoming
connection overwriting the status of the outgoing one. And this could
lead to all kind of weirdness (even crashes!) later on.

So now such incoming connections are dropped. But this most probably
prevents the two servers from linking until timing changes somehow
(network latency?) because each server drops the incoming connection of
the other one, so no connection survives in the end.

But this has to be addressed by an other patch ...

commit - d7b5dd1bbf44ff9c8537def6d2083891b4f7d102
commit + eb4f9eac0c35071838c9367f1204db0d0b98ad2e
blob - b60057070f5077bf71c2898368c98b21b795788f
blob + 6a7f63393c6f7177f054b991e72a15009cf6fa1c
--- src/ngircd/conf.c
+++ src/ngircd/conf.c
@@ -490,7 +490,7 @@ Conf_UnsetServer( CONN_ID Idx )
 /**
  * Set connection information for specified configured server.
  */
-GLOBAL void
+GLOBAL bool
 Conf_SetServer( int ConfServer, CONN_ID Idx )
 {
 	assert( ConfServer > NONE );
@@ -498,13 +498,15 @@ Conf_SetServer( int ConfServer, CONN_ID Idx )
 
 	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;
+		Log(LOG_ERR,
+		    "Connection %d: Server configuration of \"%s\" already in use by connection %d!",
+		    Idx, Conf_Server[ConfServer].name,
+		    Conf_Server[ConfServer].conn_id);
+		Conn_Close(Idx, NULL, "Server configuration already in use", true);
+		return false;
 	}
 	Conf_Server[ConfServer].conn_id = Idx;
+	return true;
 }
 
 /**
blob - 541fdb294c4aac81114f7b8c458dc4e6f81021f2
blob + 7860f019a8928d2959ed0e31e82fc3e18c34149d
--- src/ngircd/conf.h
+++ src/ngircd/conf.h
@@ -242,7 +242,7 @@ GLOBAL bool Conf_Rehash PARAMS((void));
 GLOBAL int Conf_Test PARAMS((void));
 
 GLOBAL void Conf_UnsetServer PARAMS(( CONN_ID Idx ));
-GLOBAL void Conf_SetServer PARAMS(( int ConfServer, CONN_ID Idx ));
+GLOBAL bool Conf_SetServer PARAMS(( int ConfServer, CONN_ID Idx ));
 GLOBAL int Conf_GetServer PARAMS(( CONN_ID Idx ));
 
 GLOBAL bool Conf_EnableServer PARAMS(( const char *Name, UINT16 Port ));
blob - 5d086857dcd2f634ab4ec5b506d57ddf3f9d3ce2
blob + 80b085a83e2f3e4b6108ed36c30c8358ff5ac441
--- src/ngircd/conn.c
+++ src/ngircd/conn.c
@@ -2079,7 +2079,8 @@ New_Server( int Server , ng_ipaddr_t *dest)
 	Client_SetToken( c, TOKEN_OUTBOUND );
 
 	/* Register connection */
-	Conf_SetServer(Server, new_sock);
+	if (!Conf_SetServer(Server, new_sock))
+		return;
 	My_Connections[new_sock].sock = new_sock;
 	My_Connections[new_sock].addr = *dest;
 	My_Connections[new_sock].client = c;
blob - 79facf5e0ead3a639c475956cc1a34a46aa1d4fc
blob + 02e3ae824e2d9c644e7f009d49db33ac8314a8a0
--- src/ngircd/irc-server.c
+++ src/ngircd/irc-server.c
@@ -104,6 +104,10 @@ IRC_SERVER( CLIENT *Client, REQUEST *Req )
 		if (!Client_CheckID(Client, Req->argv[0]))
 			return DISCONNECTED;
 
+		/* Mark this connection as belonging to an configured server */
+		if (!Conf_SetServer(i, Client_Conn(Client)))
+			return DISCONNECTED;
+
 		Client_SetID( Client, Req->argv[0] );
 		Client_SetHops( Client, 1 );
 		Client_SetInfo( Client, Req->argv[Req->argc - 1] );
@@ -131,9 +135,6 @@ IRC_SERVER( CLIENT *Client, REQUEST *Req )
 			Client_SetToken(Client, atoi(Req->argv[1]));
 		}
 
-		/* Mark this connection as belonging to an configured server */
-		Conf_SetServer(i, Client_Conn(Client));
-
 		/* Check protocol level */
 		if (Client_Type(Client) == CLIENT_GOTPASS) {
 			/* We got a "simple" PASS command, so the peer is