block/nbd: Reject port parameter without host

Currently, a port that is passed along with a UNIX socket path is
silently ignored. That is not exactly ideal, it should be an error
instead.
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/nbd.c

@@ -197,6 +197,7 @@ static SocketAddress *nbd_config(BDRVNBDState *s, QemuOpts *opts, Error **errp)
 
     s->path = g_strdup(qemu_opt_get(opts, "path"));
     s->host = g_strdup(qemu_opt_get(opts, "host"));
+    s->port = g_strdup(qemu_opt_get(opts, "port"));
 
     if (!s->path == !s->host) {
         if (s->path) {
@@ -206,6 +207,10 @@ static SocketAddress *nbd_config(BDRVNBDState *s, QemuOpts *opts, Error **errp)
         }
         return NULL;
     }
+    if (s->port && !s->host) {
+        error_setg(errp, "port may not be used without host");
+        return NULL;
+    }
 
     saddr = g_new0(SocketAddress, 1);
 
@@ -217,8 +222,6 @@ static SocketAddress *nbd_config(BDRVNBDState *s, QemuOpts *opts, Error **errp)
     } else {
         InetSocketAddress *inet;
 
-        s->port = g_strdup(qemu_opt_get(opts, "port"));
-
         saddr->type = SOCKET_ADDRESS_KIND_INET;
         inet = saddr->u.inet.data = g_new0(InetSocketAddress, 1);
         inet->host = g_strdup(s->host);