tcp: Replace source address also if it's the same as the guest address

...not just for loopback addresses, with the address of the default
gateway. Otherwise, the guest might receive packets with source and
destination set to the same address.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/tcp.c b/tcp.c
index 58af89f..efcf466 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1814,7 +1814,8 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	if (ref.tcp.v6) {
 		struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)&sa;
 
-		if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
+		if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr) ||
+		    !memcmp(&sa6->sin6_addr, &c->addr6_seen, sizeof(c->addr6)))
 			memcpy(&sa6->sin6_addr, &c->gw6, sizeof(c->gw6));
 
 		memcpy(&conn->a.a6, &sa6->sin6_addr, sizeof(conn->a.a6));
@@ -1835,7 +1836,8 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 		memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one));
 
 		if (ntohl(sa4->sin_addr.s_addr) == INADDR_LOOPBACK ||
-		    ntohl(sa4->sin_addr.s_addr) == INADDR_ANY)
+		    ntohl(sa4->sin_addr.s_addr) == INADDR_ANY ||
+		    sa4->sin_addr.s_addr == c->addr4_seen)
 			sa4->sin_addr.s_addr = c->gw4;
 
 		memcpy(&conn->a.a4.a, &sa4->sin_addr, sizeof(conn->a.a4.a));