From ddffeb1ceb781cfb17ca83e846de835ffd4bda54 Mon Sep 17 00:00:00 2001
From: fendo <fendo@bi12info.com>
Date: Wed, 26 Dec 2012 11:13:09 +0100
Subject: [PATCH] Authorize to change the source IP of the tunnels l2tp

---
 Docs/manual.html | 12 ++++++++++++
 debian/changelog |  6 ++++++
 l2tpns.c         | 15 ++++++++++++++-
 l2tpns.h         |  1 +
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/Docs/manual.html b/Docs/manual.html
index d6930dd..4215189 100644
--- a/Docs/manual.html
+++ b/Docs/manual.html
@@ -265,6 +265,10 @@ from the address of "bind_address" (For use in cases of specific configuration).
 If no address is given to iftun_address and bind_address, 1.1.1.1 is used.
 </LI>
 
+<LI><B>tundevicename</B> (string)<BR>
+Name of the tun interface (default: "tun0").
+</LI>
+
 <LI><B>peer_address</B> (ip address)<BR>
 Address to send to clients as the default gateway.
 </LI>
@@ -384,6 +388,14 @@ If no address is given, all interfaces are listened (Any Address).
 Port to bind for the Remote LNS (default: 65432).
 </LI>
 
+<LI><B>auth_tunnel_change_addr_src</B> (boolean)<BR>
+This parameter authorize to change the source IP of the tunnels l2tp.
+This parameter can be used when the remotes BAS/LAC are l2tpns server
+configured in cluster mode, but that the interface to remote LNS are
+not clustered (the tunnel can be coming from different source IP)
+(default: no).
+</LI>
+
 </UL>
 
 <P>The REMOTES LNS configuration is entered by the command:
diff --git a/debian/changelog b/debian/changelog
index bcba095..a9aa82b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+l2tpns (2.2.1-2fdn3.2) unstable; urgency=low
+
+  * Authorize to change the source IP of the tunnels l2tp.
+
+ -- Fernando Alves <fernando.alves@sameswireless.fr>  Wed, 26 Dec 2012 10:57:10 +0100
+
 l2tpns (2.2.1-2fdn3.1) unstable; urgency=low
 
   * Add tundevicename configuration option
diff --git a/l2tpns.c b/l2tpns.c
index 5f3b865..9db5bc3 100644
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -182,6 +182,7 @@ config_descriptt config_values[] = {
 	CONFIG("tundevicename", tundevicename, STRING),
 #ifdef LAC
 	CONFIG("disable_lac_func", disable_lac_func, BOOL),
+	CONFIG("auth_tunnel_change_addr_src", auth_tunnel_change_addr_src, BOOL),
 	CONFIG("bind_address_remotelns", bind_address_remotelns, IPv4),
 	CONFIG("bind_portremotelns", bind_portremotelns, SHORT),
 #endif
@@ -3229,10 +3230,22 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
 		if (session[s].forwardtosession)
 		{
 			LOG(5, s, t, "Forwarding data session to session %u\n", session[s].forwardtosession);
-			// Forward to LAC or Remote LNS session
+			// Forward to LAC/BAS or Remote LNS session
 			lac_session_forward(buf, len, s, proto, addr->sin_addr.s_addr, addr->sin_port);
 			return;
 		}
+		else if (config->auth_tunnel_change_addr_src)
+		{
+			if (tunnel[t].ip != ntohl(addr->sin_addr.s_addr) &&
+				tunnel[t].port == ntohs(addr->sin_port))
+			{
+				// The remotes BAS are a clustered l2tpns server and the source IP has changed
+				LOG(5, s, t, "The tunnel IP source (%s) has changed by new IP (%s)\n",
+					fmtaddr(htonl(tunnel[t].ip), 0), fmtaddr(addr->sin_addr.s_addr, 0));
+
+				tunnel[t].ip = ntohl(addr->sin_addr.s_addr);
+			}
+		}
 #endif /* LAC */
 
 		if (s && !session[s].opened)	// Is something wrong??
diff --git a/l2tpns.h b/l2tpns.h
index ba9a56f..5dbaee7 100644
--- a/l2tpns.h
+++ b/l2tpns.h
@@ -764,6 +764,7 @@ typedef struct
 	in_addr_t iftun_address;
 #ifdef LAC
 	int disable_lac_func;
+	int auth_tunnel_change_addr_src;
 	int highest_rlnsid;
 	uint16_t bind_portremotelns;
 	in_addr_t bind_address_remotelns;
-- 
2.20.1