tap: Fill the IPv6 flow label field to represent flow association

This isn't optional: TCP streams must carry a unique, hard-to-guess,
non-zero label for each direction. Linux, probably among others,
will otherwise refuse to associate packets in a given stream to the
same connection.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/dhcpv6.c b/dhcpv6.c
index 31ef66d..f982cde 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -520,7 +520,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 			resp_not_on_link.hdr.xid = mh->xid;
 
 			tap_ip_send(c, &c->gw6, IPPROTO_UDP,
-				    (char *)&resp_not_on_link, n);
+				    (char *)&resp_not_on_link, n, mh->xid);
 
 			return 1;
 		}
@@ -569,7 +569,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 
 	resp.hdr.xid = mh->xid;
 
-	tap_ip_send(c, &c->gw6, IPPROTO_UDP, (char *)&resp, n);
+	tap_ip_send(c, &c->gw6, IPPROTO_UDP, (char *)&resp, n, mh->xid);
 	c->addr6_seen = c->addr6;
 
 	return 1;