tcp, udp: Restore usage of gateway for guest to connect to local host

This went lost in a recent rework: if the guest wants to connect
directly to the host, it can use the address of the default gateway.

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

2 files changed, 11 insertions, 6 deletions

diff --git a/tcp.c b/tcp.c
index eb83cc4..8aa9740 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1387,6 +1387,11 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 	if (s < 0)
 		return;
 
+	if (af == AF_INET && addr4.sin_addr.s_addr == c->gw4)
+		addr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+	else if (af == AF_INET6 && !memcmp(addr, &c->gw6, sizeof(c->gw6)))
+		addr6.sin6_addr = in6addr_loopback;
+
 	if (af == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&addr6.sin6_addr)) {
 		struct sockaddr_in6 addr6_ll = {
 			.sin6_family = AF_INET6,
diff --git a/udp.c b/udp.c
index 097e263..e3bb1e6 100644
--- a/udp.c
+++ b/udp.c
@@ -923,9 +923,9 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
 
 		udp_tap_map[V4][src].ts = now->tv_sec;
 
-		if (s_in.sin_addr.s_addr == c->gw4 &&
-		    udp_tap_map[V4][dst].ts_local) {
-			if (udp_tap_map[V4][dst].loopback)
+		if (s_in.sin_addr.s_addr == c->gw4) {
+			if (!udp_tap_map[V4][dst].ts_local ||
+			    udp_tap_map[V4][dst].loopback)
 				s_in.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
 			else
 				s_in.sin_addr.s_addr = c->addr4_seen;
@@ -941,9 +941,9 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
 		sa = (struct sockaddr *)&s_in6;
 		sl = sizeof(s_in6);
 
-		if (!memcmp(addr, &c->gw6, sizeof(c->gw6)) &&
-		    udp_tap_map[V6][dst].ts_local) {
-			if (udp_tap_map[V6][dst].loopback)
+		if (!memcmp(addr, &c->gw6, sizeof(c->gw6))) {
+			if (!udp_tap_map[V6][dst].ts_local ||
+			    udp_tap_map[V6][dst].loopback)
 				s_in6.sin6_addr = in6addr_loopback;
 			else
 				s_in6.sin6_addr = c->addr6_seen;