http: emit 'error' on aborted client response

Client responses aka. IncomingMessage emits 'aborted'
instead of 'error' which causes confusion when
the object is used as a regular stream, i.e. if
functions working on streams are passed a
client response object they might not work properly
unless they take this into account.

Refs: nodejs/web-server-frameworks#41
Fixes: #28172

doc/api/http.md

@@ -333,9 +333,8 @@ Until the data is consumed, the `'end'` event will not fire. Also, until
 the data is read it will consume memory that can eventually lead to a
 'process out of memory' error.
 
-Unlike the `request` object, if the response closes prematurely, the
-`response` object does not emit an `'error'` event but instead emits the
-`'aborted'` event.
+For backward compatibility, `res` will only emit `'error'` if there is an
+`'error'` listener registered.
 
 Node.js does not check whether Content-Length and the length of the
 body which has been transmitted are equal or not.
@@ -2404,6 +2403,8 @@ the following events will be emitted in the following order:
   * `'data'` any number of times, on the `res` object
 * (connection closed here)
 * `'aborted'` on the `res` object
+* `'error'` on the `res` object with an error with message
+  `'Error: socket hang up'` and code `'ECONNRESET'`.
 * `'close'`
 * `'close'` on the `res` object
 
@@ -2432,6 +2433,8 @@ events will be emitted in the following order:
   * `'data'` any number of times, on the `res` object
 * (`req.destroy()` called here)
 * `'aborted'` on the `res` object
+* `'error'` on the `res` object with an error with message
+  `'Error: socket hang up'` and code `'ECONNRESET'`.
 * `'close'`
 * `'close'` on the `res` object
 
@@ -2461,6 +2464,8 @@ events will be emitted in the following order:
 * (`req.abort()` called here)
 * `'abort'`
 * `'aborted'` on the `res` object
+* `'error'` on the `res` object with an error with message
+  `'Error: socket hang up'` and code `'ECONNRESET'`.
 * `'close'`
 * `'close'` on the `res` object
 

lib/_http_client.js

@@ -413,9 +413,13 @@ function socketCloseListener() {
   const res = req.res;
   if (res) {
     // Socket closed before we emitted 'end' below.
+    // TOOD(ronag): res.destroy(err)
     if (!res.complete) {
       res.aborted = true;
       res.emit('aborted');
+      if (res.listenerCount('error') > 0) {
+        res.emit('error', connResetException('aborted'));
+      }
     }
     req.emit('close');
     if (!res.aborted && res.readable) {

test/parallel/test-http-abort-client.js

@@ -21,6 +21,7 @@
 
 'use strict';
 const common = require('../common');
+const assert = require('assert');
 const http = require('http');
 
 let serverRes;
@@ -41,6 +42,9 @@ server.listen(0, common.mustCall(() => {
     res.resume();
     res.on('end', common.mustNotCall());
     res.on('aborted', common.mustCall());
+    res.on('error', common.mustCall((err) => {
+      assert.strictEqual(err.code, 'ECONNRESET');
+    }));
     res.on('close', common.mustCall());
     res.socket.on('close', common.mustCall());
   }));

test/parallel/test-http-aborted.js

@@ -25,6 +25,9 @@ const assert = require('assert');
       res.on('aborted', common.mustCall(() => {
         assert.strictEqual(res.aborted, true);
       }));
+      res.on('error', common.mustCall((err) => {
+        assert.strictEqual(err.code, 'ECONNRESET');
+      }));
       req.abort();
     }));
   }));
@@ -36,6 +39,7 @@ const assert = require('assert');
   const server = http.createServer(common.mustCall(function(req, res) {
     req.on('aborted', common.mustCall(function() {
       assert.strictEqual(this.aborted, true);
+      server.close();
     }));
     assert.strictEqual(req.aborted, false);
     res.write('hello');

test/parallel/test-http-client-aborted-event.js

@@ -1,20 +1,46 @@
 'use strict';
 const common = require('../common');
 const http = require('http');
+const assert = require('assert');
 
-let serverRes;
-const server = http.Server(function(req, res) {
-  res.write('Part of my res.');
-  serverRes = res;
-});
+{
+  let serverRes;
+  const server = http.Server(function(req, res) {
+    res.write('Part of my res.');
+    serverRes = res;
+  });
 
-server.listen(0, common.mustCall(function() {
-  http.get({
-    port: this.address().port,
-    headers: { connection: 'keep-alive' }
-  }, common.mustCall(function(res) {
-    server.close();
-    serverRes.destroy();
-    res.on('aborted', common.mustCall());
+  server.listen(0, common.mustCall(function() {
+    http.get({
+      port: this.address().port,
+      headers: { connection: 'keep-alive' }
+    }, common.mustCall(function(res) {
+      server.close();
+      serverRes.destroy();
+      res.on('aborted', common.mustCall());
+      res.on('error', common.mustCall((err) => {
+        assert.strictEqual(err.code, 'ECONNRESET');
+      }));
+    }));
   }));
-}));
+}
+
+{
+  // Don't crash of no 'error' handler.
+  let serverRes;
+  const server = http.Server(function(req, res) {
+    res.write('Part of my res.');
+    serverRes = res;
+  });
+
+  server.listen(0, common.mustCall(function() {
+    http.get({
+      port: this.address().port,
+      headers: { connection: 'keep-alive' }
+    }, common.mustCall(function(res) {
+      server.close();
+      serverRes.destroy();
+      res.on('aborted', common.mustCall());
+    }));
+  }));
+}

test/parallel/test-http-client-spurious-aborted.js

@@ -60,15 +60,18 @@ function download() {
       res.on('end', common.mustCall(() => {
         reqCountdown.dec();
       }));
+      res.on('error', common.mustNotCall());
     } else {
       res.on('aborted', common.mustCall(() => {
         aborted = true;
         reqCountdown.dec();
         writable.end();
       }));
+      res.on('error', common.mustCall((err) => {
+        assert.strictEqual(err.code, 'ECONNRESET');
+      }));
     }
 
-    res.on('error', common.mustNotCall());
     writable.on('finish', () => {
       assert.strictEqual(aborted, abortRequest);
       finishCountdown.dec();

test/parallel/test-http-outgoing-message-capture-rejection.js

@@ -33,6 +33,9 @@ events.captureRejections = true;
 
     req.on('response', common.mustCall((res) => {
       res.on('aborted', common.mustCall());
+      res.on('error', common.mustCall((err) => {
+        assert.strictEqual(err.code, 'ECONNRESET');
+      }));
       res.resume();
       server.close();
     }));