net: improve arbitrary tcp socket support

Consider this example:

  // fd 3 is a bound tcp socket
  var s = net.createServer(cb);
  s.listen({ fd: 3 });
  console.log(s.address());  // prints null

This commit makes net.Server#address() print the actual address.

Ditto for non-listen sockets; properties like net.Socket#localAddress
and net.Socket#remoteAddress now return the correct value.

Fixes #5009.

lib/net.js

@@ -42,6 +42,15 @@ function createTCP() {
 }
 
 
+function createHandle(fd) {
+  var tty = process.binding('tty_wrap');
+  var type = tty.guessHandleType(fd);
+  if (type === 'PIPE') return createPipe();
+  if (type === 'TCP') return createTCP();
+  throw new TypeError('Unsupported fd type: ' + type);
+}
+
+
 var debug;
 if (process.env.NODE_DEBUG && /net/.test(process.env.NODE_DEBUG)) {
   var pid = process.pid;
@@ -144,7 +153,7 @@ function Socket(options) {
   if (options.handle) {
     this._handle = options.handle; // private
   } else if (typeof options.fd !== 'undefined') {
-    this._handle = createPipe();
+    this._handle = createHandle(options.fd);
     this._handle.open(options.fd);
     this.readable = options.readable !== false;
     this.writable = options.writable !== false;
@@ -930,26 +939,18 @@ var createServerHandle = exports._createServerHandle =
   var handle;
 
   if (typeof fd === 'number' && fd >= 0) {
-    var tty_wrap = process.binding('tty_wrap');
+    try {
-    var type = tty_wrap.guessHandleType(fd);
+      handle = createHandle(fd);
-    switch (type) {
-      case 'PIPE':
-      case 'TCP':
-        debug('listen pipe fd=' + fd);
-        // create a PipeWrap
-        handle = createPipe();
-        handle.open(fd);
-        handle.readable = true;
-        handle.writable = true;
-        break;
-
-      default:
-        // Not a fd we can listen on.  This will trigger an error.
-        debug('listen invalid fd=' + fd + ' type=' + type);
-        process._errno = 'EINVAL'; // hack, callers expect that errno is set
-        handle = null;
-        break;
     }
+    catch (e) {
+      // Not a fd we can listen on.  This will trigger an error.
+      debug('listen invalid fd=' + fd + ': ' + e.message);
+      process._errno = 'EINVAL'; // hack, callers expect that errno is set
+      return null;
+    }
+    handle.open(fd);
+    handle.readable = true;
+    handle.writable = true;
     return handle;
 
   } else if (port == -1 && addressType == -1) {

src/tcp_wrap.cc

@@ -104,6 +104,7 @@ void TCPWrap::Initialize(Handle<Object> target) {
   NODE_SET_PROTOTYPE_METHOD(t, "writeUtf8String", StreamWrap::WriteUtf8String);
   NODE_SET_PROTOTYPE_METHOD(t, "writeUcs2String", StreamWrap::WriteUcs2String);
 
+  NODE_SET_PROTOTYPE_METHOD(t, "open", Open);
   NODE_SET_PROTOTYPE_METHOD(t, "bind", Bind);
   NODE_SET_PROTOTYPE_METHOD(t, "listen", Listen);
   NODE_SET_PROTOTYPE_METHOD(t, "connect", Connect);
@@ -256,6 +257,15 @@ Handle<Value> TCPWrap::SetSimultaneousAccepts(const Arguments& args) {
 #endif
 
 
+Handle<Value> TCPWrap::Open(const Arguments& args) {
+  HandleScope scope;
+  UNWRAP(TCPWrap)
+  int fd = args[0]->IntegerValue();
+  uv_tcp_open(&wrap->handle_, fd);
+  return Null();
+}
+
+
 Handle<Value> TCPWrap::Bind(const Arguments& args) {
   HandleScope scope;