socket: do not fallback on loopback addr for addresses in our mask/prefix

Currently, any address within the subnetwork will fallback on
loopback. It seems it has always been like that, but it seems wrong,
and I don't see a good reason to keep it this way. Fortunately, lack
of ARP reply made this unusable in practice, so we shouldn't break
much existing users.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

1 files changed, 12 insertions, 16 deletions

diff --git a/src/socket.c b/src/socket.c
index cb1684a..6ad9c30 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -821,19 +821,17 @@ void sofwdrain(struct socket *so)
 
 static bool sotranslate_out4(Slirp *s, struct socket *so, struct sockaddr_in *sin)
 {
-    if ((so->so_faddr.s_addr & s->vnetwork_mask.s_addr) ==
-        s->vnetwork_addr.s_addr) {
-        if (so->so_faddr.s_addr == s->vnameserver_addr.s_addr) {
-            return get_dns_addr(&sin->sin_addr) >= 0;
-        }
+    if (so->so_faddr.s_addr == s->vnameserver_addr.s_addr) {
+        return get_dns_addr(&sin->sin_addr) >= 0;
+    }
+
+    if (so->so_faddr.s_addr == s->vhost_addr.s_addr ||
+        so->so_faddr.s_addr == 0xffffffff) {
         if (s->disable_host_loopback) {
             return false;
         }
 
         sin->sin_addr = loopback_addr;
-    } else if (!s->disable_host_loopback && so->so_faddr.s_addr == 0xffffffff) {
-        /* Receive broadcast as well */
-        sin->sin_addr = loopback_addr;
     }
 
     return true;
@@ -841,19 +839,17 @@ static bool sotranslate_out4(Slirp *s, struct socket *so, struct sockaddr_in *si
 
 static bool sotranslate_out6(Slirp *s, struct socket *so, struct sockaddr_in6 *sin)
 {
-    if (in6_equal_net(&so->so_faddr6, &s->vprefix_addr6, s->vprefix_len)) {
-        if (in6_equal(&so->so_faddr6, &s->vnameserver_addr6)) {
-            return get_dns6_addr(&sin->sin6_addr, &sin->sin6_scope_id) >= 0;
-        }
+    if (in6_equal(&so->so_faddr6, &s->vnameserver_addr6)) {
+        return get_dns6_addr(&sin->sin6_addr, &sin->sin6_scope_id) >= 0;
+    }
+
+    if (in6_equal_net(&so->so_faddr6, &s->vprefix_addr6, s->vprefix_len) ||
+        in6_equal(&so->so_faddr6, &(struct in6_addr)ALLNODES_MULTICAST)) {
         if (s->disable_host_loopback) {
             return false;
         }
 
         sin->sin6_addr = in6addr_loopback;
-    } else if (!s->disable_host_loopback &&
-               in6_equal(&so->so_faddr6,
-                         &(struct in6_addr)ALLNODES_MULTICAST)) {
-        sin->sin6_addr = in6addr_loopback;
     }
 
     return true;