http: send implicit headers on HEAD with no body

If we respond to a HEAD request with a body, we ignore all writes. However, we must still include all implicit headers. Fixes a regressions introduced in #47732. Signed-off-by: Matteo Collina <hello@matteocollina.com> PR-URL: #48108 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Robert Nagy <ronagy@icloud.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

Author: mcollina

lib/_http_outgoing.js

@@ -887,17 +887,6 @@ function write_(msg, chunk, encoding, callback, fromEnd) {
  err = new ERR_STREAM_DESTROYED('write');
  }
 
- if (!msg._hasBody) {
- if (msg[kRejectNonStandardBodyWrites]) {
- throw new ERR_HTTP_BODY_NOT_ALLOWED();
- } else {
- debug('This type of response MUST NOT have a body. ' +
- 'Ignoring write() calls.');
- process.nextTick(callback);
- return true;
- }
- }
-
  if (err) {
  if (!msg.destroyed) {
  onError(msg, err, callback);
@@ -930,6 +919,17 @@ function write_(msg, chunk, encoding, callback, fromEnd) {
  msg._implicitHeader();
  }
 
+ if (!msg._hasBody) {
+ if (msg[kRejectNonStandardBodyWrites]) {
+ throw new ERR_HTTP_BODY_NOT_ALLOWED();
+ } else {
+ debug('This type of response MUST NOT have a body. ' +
+ 'Ignoring write() calls.');
+ process.nextTick(callback);
+ return true;
+ }
+ }
+
  if (!fromEnd && msg.socket && !msg.socket.writableCorked) {
  msg.socket.cork();
  process.nextTick(connectionCorkNT, msg.socket);

test/parallel/test-http-head-response-has-no-body-end-implicit-headers.js

@@ -0,0 +1,27 @@
+'use strict';
+const common = require('../common');
+const http = require('http');
+
+// This test is to make sure that when the HTTP server
+// responds to a HEAD request with data to res.end,
+// it does not send any body but the response is sent
+// anyway.
+
+const server = http.createServer(function(req, res) {
+ res.end('FAIL'); // broken: sends FAIL from hot path.
+});
+server.listen(0);
+
+server.on('listening', common.mustCall(function() {
+ const req = http.request({
+ port: this.address().port,
+ method: 'HEAD',
+ path: '/'
+ }, common.mustCall(function(res) {
+ res.on('end', common.mustCall(function() {
+ server.close();
+ }));
+ res.resume();
+ }));
+ req.end();
+}));

test/parallel/test-http-head-response-has-no-body-end.js

@@ -29,7 +29,7 @@ const http = require('http');
 
 const server = http.createServer(function(req, res) {
  res.writeHead(200);
- res.end();
+ res.end('FAIL'); // broken: sends FAIL from hot path.
 });
 server.listen(0);