http2: refactor error handling

This changes the error handling model of ServerHttp2Stream,
ServerHttp2Request and ServerHttp2Response.
An 'error' emitted on ServerHttp2Stream will not go to
'uncaughtException' anymore, but to the server 'streamError'.
On the stream 'error', ServerHttp2Request will emit 'abort', while
ServerHttp2Response would do nothing

See: nodejs/node#14963

PR-URL: nodejs/node#14991
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: mcollina

doc/api/http2.md

@@ -1118,6 +1118,8 @@ added: v8.4.0
 * `headers` {[Headers Object][]}
 * `options` {Object}
   * `statCheck` {Function}
+  * `onError` {Function} Callback function invoked in the case of an
+    Error before send
   * `getTrailers` {Function} Callback function invoked to collect trailer
     headers.
   * `offset` {number} The offset position at which to begin reading
@@ -1146,6 +1148,16 @@ server.on('stream', (stream) => {
   function statCheck(stat, headers) {
     headers['last-modified'] = stat.mtime.toUTCString();
   }
+
+  function onError(err) {
+    if (err.code === 'ENOENT') {
+      stream.respond({ ':status': 404 });
+    } else {
+      stream.respond({ ':status': 500 });
+    }
+    stream.end();
+  }
+
   stream.respondWithFile('/some/file',
                          { 'content-type': 'text/plain' },
                          { statCheck });
@@ -1178,6 +1190,10 @@ The `offset` and `length` options may be used to limit the response to a
 specific range subset. This can be used, for instance, to support HTTP Range
 requests.
 
+The `options.onError` function may also be used to handle all the errors
+that could happen before the delivery of the file is initiated. The
+default behavior is to destroy the stream.
+
 When set, the `options.getTrailers()` function is called immediately after
 queuing the last chunk of payload data to be sent. The callback is passed a
 single object (with a `null` prototype) that the listener may used to specify
@@ -1208,6 +1224,19 @@ added: v8.4.0
 
 * Extends: {net.Server}
 
+In `Http2Server`, there is no `'clientError'` event as there is in
+HTTP1. However, there are `'socketError'`, `'sessionError'`,  and
+`'streamError'`, for error happened on the socket, session or stream
+respectively.
+
+#### Event: 'socketError'
+<!-- YAML
+added: v8.4.0
+-->
+
+The `'socketError'` event is emitted when a `'socketError'` event is emitted by
+an `Http2Session` associated with the server.
+
 #### Event: 'sessionError'
 <!-- YAML
 added: v8.4.0
@@ -1217,13 +1246,15 @@ The `'sessionError'` event is emitted when an `'error'` event is emitted by
 an `Http2Session` object. If no listener is registered for this event, an
 `'error'` event is emitted.
 
-#### Event: 'socketError'
+#### Event: 'streamError'
 <!-- YAML
-added: v8.4.0
+added: REPLACEME
 -->
 
-The `'socketError'` event is emitted when a `'socketError'` event is emitted by
-an `Http2Session` associated with the server.
+* `socket` {http2.ServerHttp2Stream}
+
+If an `ServerHttp2Stream` emits an `'error'` event, it will be forwarded here.
+The stream will already be destroyed when this event is triggered.
 
 #### Event: 'stream'
 <!-- YAML

lib/http2.js

@@ -15,7 +15,7 @@ const {
   createSecureServer,
   connect,
   Http2ServerRequest,
-  Http2ServerResponse,
+  Http2ServerResponse
 } = require('internal/http2/core');
 
 module.exports = {
@@ -27,5 +27,5 @@ module.exports = {
   createSecureServer,
   connect,
   Http2ServerResponse,
-  Http2ServerRequest,
+  Http2ServerRequest
 };

lib/internal/http2/compat.js

@@ -58,8 +58,13 @@ function onStreamEnd() {
 }
 
 function onStreamError(error) {
-  const request = this[kRequest];
-  request.emit('error', error);
+  // this is purposefully left blank
+  //
+  // errors in compatibility mode are
+  // not forwarded to the request
+  // and response objects. However,
+  // they are forwarded to 'clientError'
+  // on the server by Http2Stream
 }
 
 function onRequestPause() {
@@ -82,11 +87,6 @@ function onStreamResponseDrain() {
   response.emit('drain');
 }
 
-function onStreamResponseError(error) {
-  const response = this[kResponse];
-  response.emit('error', error);
-}
-
 function onStreamClosedRequest() {
   const req = this[kRequest];
   req.push(null);
@@ -271,9 +271,7 @@ class Http2ServerResponse extends Stream {
     stream[kResponse] = this;
     this.writable = true;
     stream.on('drain', onStreamResponseDrain);
-    stream.on('error', onStreamResponseError);
     stream.on('close', onStreamClosedResponse);
-    stream.on('aborted', onAborted.bind(this));
     const onfinish = this[kFinish].bind(this);
     stream.on('streamClosed', onfinish);
     stream.on('finish', onfinish);

lib/internal/http2/core.js

@@ -1506,6 +1506,13 @@ class Http2Stream extends Duplex {
       this.once('ready', this._destroy.bind(this, err, callback));
       return;
     }
+
+    const server = session[kServer];
+
+    if (err && server) {
+      server.emit('streamError', err, this);
+    }
+
     process.nextTick(() => {
       debug(`[${sessionName(session[kType])}] destroying stream ${this[kID]}`);
 
@@ -1529,9 +1536,8 @@ class Http2Stream extends Duplex {
       // All done
       const rst = this[kState].rst;
       const code = rst ? this[kState].rstCode : NGHTTP2_NO_ERROR;
-      if (code !== NGHTTP2_NO_ERROR) {
-        const err = new errors.Error('ERR_HTTP2_STREAM_ERROR', code);
-        process.nextTick(() => this.emit('error', err));
+      if (!err && code !== NGHTTP2_NO_ERROR) {
+        err = new errors.Error('ERR_HTTP2_STREAM_ERROR', code);
       }
       process.nextTick(emit.bind(this, 'streamClosed', code));
       debug(`[${sessionName(session[kType])}] stream ${this[kID]} destroyed`);
@@ -1634,13 +1640,24 @@ function doSendFileFD(session, options, fd, headers, getTrailers, err, stat) {
     abort(this);
     return;
   }
+  const onError = options.onError;
+
   if (err) {
-    process.nextTick(() => this.emit('error', err));
+    if (onError) {
+      onError(err);
+    } else {
+      this.destroy(err);
+    }
     return;
   }
+
   if (!stat.isFile()) {
     err = new errors.Error('ERR_HTTP2_SEND_FILE');
-    process.nextTick(() => this.emit('error', err));
+    if (onError) {
+      onError(err);
+    } else {
+      this.destroy(err);
+    }
     return;
   }
 
@@ -1677,12 +1694,17 @@ function doSendFileFD(session, options, fd, headers, getTrailers, err, stat) {
 
 function afterOpen(session, options, headers, getTrailers, err, fd) {
   const state = this[kState];
+  const onError = options.onError;
   if (this.destroyed || session.destroyed) {
     abort(this);
     return;
   }
   if (err) {
-    process.nextTick(() => this.emit('error', err));
+    if (onError) {
+      onError(err);
+    } else {
+      this.destroy(err);
+    }
     return;
   }
   state.fd = fd;
@@ -1691,13 +1713,20 @@ function afterOpen(session, options, headers, getTrailers, err, fd) {
            doSendFileFD.bind(this, session, options, fd, headers, getTrailers));
 }
 
+function streamOnError(err) {
+  // we swallow the error for parity with HTTP1
+  // all the errors that ends here are not critical for the project
+  debug('ServerHttp2Stream errored, avoiding uncaughtException', err);
+}
+
 
 class ServerHttp2Stream extends Http2Stream {
   constructor(session, id, options, headers) {
     super(session, options);
     this[kInit](id);
     this[kProtocol] = headers[HTTP2_HEADER_SCHEME];
     this[kAuthority] = headers[HTTP2_HEADER_AUTHORITY];
+    this.on('error', streamOnError);
     debug(`[${sessionName(session[kType])}] created serverhttp2stream`);
   }
 
@@ -2556,6 +2585,8 @@ module.exports = {
   createServer,
   createSecureServer,
   connect,
+  Http2Session,
+  Http2Stream,
   Http2ServerRequest,
   Http2ServerResponse
 };

test/parallel/test-http2-client-stream-destroy-before-connect.js

@@ -36,18 +36,11 @@ server.on('listening', common.mustCall(() => {
   req.destroy(err);
 
   req.on('error', common.mustCall((err) => {
-    const fn = err.code === 'ERR_HTTP2_STREAM_ERROR' ?
-      common.expectsError({
-        code: 'ERR_HTTP2_STREAM_ERROR',
-        type: Error,
-        message: 'Stream closed with error code 2'
-      }) :
-      common.expectsError({
-        type: Error,
-        message: 'test'
-      });
-    fn(err);
-  }, 2));
+    common.expectsError({
+      type: Error,
+      message: 'test'
+    })(err);
+  }));
 
   req.on('streamClosed', common.mustCall((code) => {
     assert.strictEqual(req.rstCode, NGHTTP2_INTERNAL_ERROR);

test/parallel/test-http2-compat-errors.js

@@ -0,0 +1,52 @@
+// Flags: --expose-http2 --expose-internals
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const assert = require('assert');
+const h2 = require('http2');
+const { Http2Stream } = require('internal/http2/core');
+
+// Errors should not be reported both in Http2ServerRequest
+// and Http2ServerResponse
+
+let expected = null;
+
+const server = h2.createServer(common.mustCall(function(req, res) {
+  req.on('error', common.mustNotCall());
+  res.on('error', common.mustNotCall());
+  req.on('aborted', common.mustCall());
+  res.on('aborted', common.mustNotCall());
+
+  res.write('hello');
+
+  expected = new Error('kaboom');
+  res.stream.destroy(expected);
+  server.close();
+}));
+
+server.on('streamError', common.mustCall(function(err, stream) {
+  assert.strictEqual(err, expected);
+  assert.strictEqual(stream instanceof Http2Stream, true);
+}));
+
+server.listen(0, common.mustCall(function() {
+  const port = server.address().port;
+
+  const url = `http://localhost:${port}`;
+  const client = h2.connect(url, common.mustCall(function() {
+    const headers = {
+      ':path': '/foobar',
+      ':method': 'GET',
+      ':scheme': 'http',
+      ':authority': `localhost:${port}`,
+    };
+    const request = client.request(headers);
+    request.on('data', common.mustCall(function(chunk) {
+      // cause an error on the server side
+      client.destroy();
+    }));
+    request.end();
+  }));
+}));

test/parallel/test-http2-respond-file-404.js

@@ -0,0 +1,47 @@
+// Flags: --expose-http2
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const http2 = require('http2');
+const assert = require('assert');
+
+const {
+  HTTP2_HEADER_CONTENT_TYPE
+} = http2.constants;
+
+const server = http2.createServer();
+server.on('stream', (stream) => {
+  const file = './not-a-file';
+  stream.respondWithFile('./not-a-file', {
+    [HTTP2_HEADER_CONTENT_TYPE]: 'text/plain'
+  }, {
+    onError(err) {
+      common.expectsError({
+        code: 'ENOENT',
+        type: Error,
+        message: `ENOENT: no such file or directory, open '${file}'`
+      })(err);
+
+      stream.respond({ ':status': 404 });
+      stream.end();
+    },
+    statCheck: common.mustNotCall()
+  });
+});
+server.listen(0, () => {
+
+  const client = http2.connect(`http://localhost:${server.address().port}`);
+  const req = client.request();
+
+  req.on('response', common.mustCall((headers) => {
+    assert.strictEqual(headers[':status'], 404);
+  }));
+  req.on('data', common.mustNotCall());
+  req.on('end', common.mustCall(() => {
+    client.destroy();
+    server.close();
+  }));
+  req.end();
+});