From e53fccd36c5c3da010f72a4cfbc851a2926398aa Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Thu, 4 Jan 2024 00:09:24 +0100
Subject: [PATCH] Add route for session-specific subprefix of the ipv6 prefix

Otherwise with kernel acceleration we would only have the same /64 route
on all ppp devices. We need separate /96 routes on each ppp device for
packets of the /96 subprefix to be routed to the correct session.
---
 l2tpns.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/l2tpns.c b/l2tpns.c
index eb18f4f..209d637 100644
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -1247,6 +1247,15 @@ void routes6set(sessionidt s, sessiont *sp, int add)
 		if (!add || sessionbyipv6(sp->ipv6address) != s)
 			route6set(s, sp->ipv6address, 128, add);
 	}
+	else
+	{
+		in_addr_t addr_ipv4 = htonl(session[s].ip);
+		struct in6_addr addr;
+		memset(&addr, 0, sizeof(addr));
+		memcpy(&addr, &config->ipv6_prefix, 8);
+		memcpy(&addr.s6_addr[8], &addr_ipv4, 4);
+		route6set(s, addr, 96, add);
+	}
 }
 
 //