http: fix ServerResponse does not emit 'close'

Refs #2453.

doc/api/http.markdown

@@ -247,6 +247,13 @@ authentication details.
 This object is created internally by a HTTP server--not by the user. It is
 passed as the second parameter to the `'request'` event. It is a `Writable Stream`.
 
+### Event: 'close'
+
+`function () { }`
+
+Indicates that the underlaying connection was terminated before
+`response.end()` was called or able to flush.
+
 ### response.writeContinue()
 
 Sends a HTTP/1.1 100 Continue message to the client, indicating that

lib/http.js

@@ -343,22 +343,6 @@ util.inherits(OutgoingMessage, stream.Stream);
 exports.OutgoingMessage = OutgoingMessage;
 
 
-OutgoingMessage.prototype.assignSocket = function(socket) {
-  assert(!socket._httpMessage);
-  socket._httpMessage = this;
-  this.socket = socket;
-  this.connection = socket;
-  this._flush();
-};
-
-
-OutgoingMessage.prototype.detachSocket = function(socket) {
-  assert(socket._httpMessage == this);
-  socket._httpMessage = null;
-  this.socket = this.connection = null;
-};
-
-
 OutgoingMessage.prototype.destroy = function(error) {
   this.socket.destroy(error);
 };
@@ -792,6 +776,26 @@ exports.ServerResponse = ServerResponse;
 
 ServerResponse.prototype.statusCode = 200;
 
+function onServerResponseClose() {
+  this._httpMessage.emit('close');
+}
+
+ServerResponse.prototype.assignSocket = function(socket) {
+  assert(!socket._httpMessage);
+  socket._httpMessage = this;
+  socket.on('close', onServerResponseClose);
+  this.socket = socket;
+  this.connection = socket;
+  this._flush();
+};
+
+ServerResponse.prototype.detachSocket = function(socket) {
+  assert(socket._httpMessage == this);
+  socket.removeListener('close', onServerResponseClose);
+  socket._httpMessage = null;
+  this.socket = this.connection = null;
+};
+
 ServerResponse.prototype.writeContinue = function() {
   this._writeRaw('HTTP/1.1 100 Continue' + CRLF + CRLF, 'ascii');
   this._sent100 = true;

test/simple/test-http-response-close.js

@@ -23,15 +23,20 @@ var common = require('../common');
 var assert = require('assert');
 var http = require('http');
 
-var gotEnd = false;
+var requestGotEnd = false;
+var responseGotEnd = false;
 
 var server = http.createServer(function(req, res) {
   res.writeHead(200);
   res.write('a');
 
   req.on('close', function() {
-    console.error('aborted');
-    gotEnd = true;
+    console.error('request aborted');
+    requestGotEnd = true;
+  });
+  res.on('close', function() {
+    console.error('response aborted');
+    responseGotEnd = true;
   });
 });
 server.listen(common.PORT);
@@ -51,5 +56,6 @@ server.on('listening', function() {
 });
 
 process.on('exit', function() {
-  assert.ok(gotEnd);
+  assert.ok(requestGotEnd);
+  assert.ok(responseGotEnd);
 });