cluster: fix libuv assert in net.listen()

Problem: calling `server.listen()` (no port) on a net.Server triggered the
following libuv assertion:

  node: ../deps/uv/src/unix/stream.c:406: uv__write: Assertion `fd_to_send >= 0'
  failed.

Cause: uv_tcp_t handles are lazily initialized. Omitting the port made the
handle get initialized even more lazily. Too lazily - it wasn't initialized
when the handle was sent over to the child process.

Solution: implicitly bind to a random port in listen() when the port number
is omitted, it forces the handle to initialize. This is not a change in
behavior, listen() has always been identical to listen(0).

Fixes #3325.

1 files changed, 2 insertions, 3 deletions

diff --git a/lib/net.js b/lib/net.js
index 170c06e57a6..b6cbe4f5410 100644
--- a/lib/net.js
+++ b/lib/net.js
@@ -967,9 +967,8 @@ Server.prototype.listen = function() {
   var TCP = process.binding('tcp_wrap').TCP;
 
   if (arguments.length == 0 || typeof arguments[0] == 'function') {
-    // Don't bind(). OS will assign a port with INADDR_ANY.
-    // The port can be found with server.address()
-    listen(self, null, null, backlog);
+    // Bind to a random port.
+    listen(self, '0.0.0.0', 0, null, backlog);
 
   } else if (arguments[0] && typeof arguments[0] === 'object') {
     var h = arguments[0];