udp: Use IP_FREEBIND for flow sockets as well as listening sockets

The --freebind option allows pasta to listen on addresses that aren't
registered on the host, which has a number of use cases.  However, we
omitted this option for UDP "flow sockets" which are created once a flow
is started, connect()ed specifically to the peer.  Flow sockets are also
bound, and if the peer has contacted a freebind address, we need
IP_FREEBIND to do so.

Link: https://bugs.passt.top/show_bug.cgi?id=174
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/util.c b/util.c
index 44c21a3..ab23463 100644
--- a/util.c
+++ b/util.c
@@ -67,9 +67,8 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
 		freebind = c->freebind;
 		break;
 	case EPOLL_TYPE_UDP_LISTEN:
-		freebind = c->freebind;
-		/* fallthrough */
 	case EPOLL_TYPE_UDP:
+		freebind = c->freebind;
 		proto = IPPROTO_UDP;
 		socktype = SOCK_DGRAM | SOCK_NONBLOCK;
 		break;