http: do not send 0\r\n\r\n in TE HEAD responses

When replying to a HEAD request, do not attempt to send the trailers and
EOF sequence (`0\r\n\r\n`). The HEAD request MUST not have body.

Quote from RFC:

The presence of a message body in a response depends on both the
request method to which it is responding and the response status code
(Section 3.1.2).  Responses to the HEAD request method (Section 4.3.2
of [RFC7231]) never include a message body because the associated
response header fields (e.g., Transfer-Encoding, Content-Length,
etc.), if present, indicate only what their values would have been if
the request method had been GET (Section 4.3.1 of [RFC7231]).

fix nodejs#8361

Reviewed-By: Timothy J Fontaine <tjfontaine@gmail.com>

lib/http.js

@@ -945,6 +945,10 @@ OutgoingMessage.prototype.end = function(data, encoding) {
   if (encoding === 'hex' || encoding === 'base64')
     hot = false;
 
+  // Transfer-encoding: chunked responses to HEAD requests
+  if (this._hasBody && this.chunkedEncoding)
+    hot = false;
+
   if (hot) {
     // Hot path. They're doing
     //   res.writeHead();
@@ -982,7 +986,7 @@ OutgoingMessage.prototype.end = function(data, encoding) {
   }
 
   if (!hot) {
-    if (this.chunkedEncoding) {
+    if (this._hasBody && this.chunkedEncoding) {
       ret = this._send('0\r\n' + this._trailer + '\r\n', 'ascii');
     } else {
       // Force a flush, HACK.

test/simple/test-http-head-request.js

@@ -26,32 +26,44 @@ var util = require('util');
 
 
 var body = 'hello world\n';
+var id = 0;
 
-var server = http.createServer(function(req, res) {
-  common.error('req: ' + req.method);
-  res.writeHead(200, {'Content-Length': body.length});
-  res.end();
-  server.close();
-});
+function test(headers) {
+  var port = common.PORT + id++;
+
+  var server = http.createServer(function(req, res) {
+    console.error('req: %s headers: %j', req.method, headers);
+    res.writeHead(200, headers);
+    res.end();
+    server.close();
+  });
+
+  var gotEnd = false;
 
-var gotEnd = false;
-
-server.listen(common.PORT, function() {
-  var request = http.request({
-    port: common.PORT,
-    method: 'HEAD',
-    path: '/'
-  }, function(response) {
-    common.error('response start');
-    response.on('end', function() {
-      common.error('response end');
-      gotEnd = true;
+  server.listen(port, function() {
+    var request = http.request({
+      port: port,
+      method: 'HEAD',
+      path: '/'
+    }, function(response) {
+      console.error('response start');
+      response.on('end', function() {
+        console.error('response end');
+        gotEnd = true;
+      });
+      response.resume();
     });
-    response.resume();
+    request.end();
   });
-  request.end();
-});
 
-process.on('exit', function() {
-  assert.ok(gotEnd);
+  process.on('exit', function() {
+    assert.ok(gotEnd);
+  });
+}
+
+test({
+  'Transfer-Encoding': 'chunked'
+});
+test({
+  'Content-Length': body.length
 });