http2: add diagnostics channel 'http2.server.stream.error'

Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/58512
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/api/diagnostics_channel.md

@@ -1252,6 +1252,13 @@ Emitted when a stream is created on the server.
 
 Emitted when a stream is started on the server.
 
+`http2.server.stream.error`
+
+* `stream` {ServerHttp2Stream}
+* `error` {Error}
+
+Emitted when an error occurs during the processing of a stream on the server.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -197,6 +197,7 @@ const onClientStreamFinishChannel = dc.channel('http2.client.stream.finish');
 const onClientStreamCloseChannel = dc.channel('http2.client.stream.close');
 const onServerStreamCreatedChannel = dc.channel('http2.server.stream.created');
 const onServerStreamStartChannel = dc.channel('http2.server.stream.start');
+const onServerStreamErrorChannel = dc.channel('http2.server.stream.error');
 
 let debug = require('internal/util/debuglog').debuglog('http2', (fn) => {
   debug = fn;
@@ -2455,13 +2456,20 @@ class Http2Stream extends Duplex {
     setImmediate(() => {
       session[kMaybeDestroy]();
     });
-    if (err &&
-        session[kType] === NGHTTP2_SESSION_CLIENT &&
-        onClientStreamErrorChannel.hasSubscribers) {
-      onClientStreamErrorChannel.publish({
-        stream: this,
-        error: err,
-      });
+    if (err) {
+      if (session[kType] === NGHTTP2_SESSION_CLIENT) {
+        if (onClientStreamErrorChannel.hasSubscribers) {
+          onClientStreamErrorChannel.publish({
+            stream: this,
+            error: err,
+          });
+        }
+      } else if (onServerStreamErrorChannel.hasSubscribers) {
+        onServerStreamErrorChannel.publish({
+          stream: this,
+          error: err,
+        });
+      }
     }
     callback(err);
   }

test/parallel/test-diagnostics-channel-http2-server-stream-error.js

@@ -0,0 +1,53 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+// This test ensures that the built-in HTTP/2 diagnostics channels are reporting
+// the diagnostics messages for the 'http2.server.stream.error' channel when
+// an error occurs during the processing of a ServerHttp2Stream.
+
+const assert = require('assert');
+const dc = require('diagnostics_channel');
+const http2 = require('http2');
+const { Duplex } = require('stream');
+
+let expectedError = null;
+
+dc.subscribe('http2.server.stream.error', common.mustCall(({ stream, error }) => {
+  // Since ServerHttp2Stream is not exported from any module, this just checks
+  // if the stream is an instance of Duplex and the constructor name is
+  // 'ServerHttp2Stream'.
+  assert.ok(stream instanceof Duplex);
+  assert.strictEqual(stream.constructor.name, 'ServerHttp2Stream');
+  assert.strictEqual(stream.closed, true);
+  assert.strictEqual(stream.destroyed, true);
+
+  assert.ok(error);
+  assert.strictEqual(error, expectedError);
+}));
+
+const server = http2.createServer();
+
+server.on('stream', common.mustCall((stream) => {
+  stream.on('error', common.mustCall((err) => {
+    assert.strictEqual(err, expectedError);
+  }));
+
+  expectedError = new Error('HTTP/2 server stream error');
+  stream.destroy(expectedError);
+}));
+
+server.listen(0, common.mustCall(() => {
+  const port = server.address().port;
+  const client = http2.connect(`http://localhost:${port}`);
+
+  const stream = client.request({});
+  stream.on('error', common.mustCall((err) => {
+    assert.strictEqual(err.code, 'ERR_HTTP2_STREAM_ERROR');
+
+    client.close();
+    server.close();
+  }));
+}));