slirp: Fix guestfwd for incoming data

Unless a virtual server address was explicitly defined (which is
impossible with the legacy -net channel format), guestfwd did not
properly forwarded host->guest packets. This patch fixes it.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

net.c

@@ -1150,7 +1150,7 @@ static void slirp_smb(SlirpState* s, Monitor *mon, const char *exported_dir,
     snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -s %s",
              SMBD_COMMAND, smb_conf);
 
-    if (slirp_add_exec(s->slirp, 0, smb_cmdline, vserver_addr, 139) < 0) {
+    if (slirp_add_exec(s->slirp, 0, smb_cmdline, &vserver_addr, 139) < 0) {
         slirp_smb_cleanup(s);
         config_error(mon, "conflicting/invalid smbserver address\n");
     }
@@ -1239,16 +1239,17 @@ static void slirp_guestfwd(SlirpState *s, Monitor *mon, const char *config_str,
         qemu_free(fwd);
         return;
     }
-    fwd->server = server;
-    fwd->port = port;
-    fwd->slirp = s->slirp;
 
-    if (slirp_add_exec(s->slirp, 3, fwd->hd, server, port) < 0) {
+    if (slirp_add_exec(s->slirp, 3, fwd->hd, &server, port) < 0) {
         config_error(mon, "conflicting/invalid host:port in guest forwarding "
                      "rule '%s'\n", config_str);
         qemu_free(fwd);
         return;
     }
+    fwd->server = server;
+    fwd->port = port;
+    fwd->slirp = s->slirp;
+
     qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
                           NULL, fwd);
     return;

slirp/libslirp.h

@@ -33,7 +33,7 @@ int slirp_add_hostfwd(Slirp *slirp, int is_udp,
 int slirp_remove_hostfwd(Slirp *slirp, int is_udp,
                          struct in_addr host_addr, int host_port);
 int slirp_add_exec(Slirp *slirp, int do_pty, const void *args,
-                   struct in_addr guest_addr, int guest_port);
+                   struct in_addr *guest_addr, int guest_port);
 
 void slirp_connection_info(Slirp *slirp, Monitor *mon);
 

slirp/slirp.c

@@ -794,19 +794,19 @@ int slirp_add_hostfwd(Slirp *slirp, int is_udp, struct in_addr host_addr,
 }
 
 int slirp_add_exec(Slirp *slirp, int do_pty, const void *args,
-                   struct in_addr guest_addr, int guest_port)
+                   struct in_addr *guest_addr, int guest_port)
 {
-    if (!guest_addr.s_addr) {
-        guest_addr.s_addr = slirp->vnetwork_addr.s_addr |
+    if (!guest_addr->s_addr) {
+        guest_addr->s_addr = slirp->vnetwork_addr.s_addr |
             (htonl(0x0204) & ~slirp->vnetwork_mask.s_addr);
     }
-    if ((guest_addr.s_addr & slirp->vnetwork_mask.s_addr) !=
+    if ((guest_addr->s_addr & slirp->vnetwork_mask.s_addr) !=
         slirp->vnetwork_addr.s_addr ||
-        guest_addr.s_addr == slirp->vhost_addr.s_addr ||
-        guest_addr.s_addr == slirp->vnameserver_addr.s_addr) {
+        guest_addr->s_addr == slirp->vhost_addr.s_addr ||
+        guest_addr->s_addr == slirp->vnameserver_addr.s_addr) {
         return -1;
     }
-    return add_exec(&slirp->exec_list, do_pty, (char *)args, guest_addr,
+    return add_exec(&slirp->exec_list, do_pty, (char *)args, *guest_addr,
                     htons(guest_port));
 }