http: add rawPacket in err of clientError event

doc/api/http.md

@@ -734,6 +734,11 @@ changes:
     description: The default action of calling `.destroy()` on the `socket`
                  will no longer take place if there are listeners attached
                  for `clientError`.
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/17672
+    description: The rawPacket is the current buffer that just parsed. Adding
+                 this buffer to the error object of clientError event is to make
+                 it possible that developers can log the broken packet.
 -->
 
 * `exception` {Error}
@@ -765,6 +770,11 @@ object, so any HTTP response sent, including response headers and payload,
 *must* be written directly to the `socket` object. Care must be taken to
 ensure the response is a properly formatted HTTP response message.
 
+`err` is an instance of `Error` with two extra columns:
+
++ `bytesParsed`: the bytes count of request packet that Node.js may have parsed correctly;
++ `rawPacket`: the raw packet of current request.
+
 ### Event: 'close'
 <!-- YAML
 added: v0.1.4

lib/_http_server.js

@@ -476,6 +476,7 @@ function onParserExecuteCommon(server, socket, parser, state, ret, d) {
   resetSocketTimeout(server, socket, state);
 
   if (ret instanceof Error) {
+    ret.rawPacket = d || parser.getCurrentBuffer();
     debug('parse error', ret);
     socketOnError.call(socket, ret);
   } else if (parser.incoming && parser.incoming.upgrade) {

test/parallel/test-http-server-client-error.js

@@ -10,6 +10,12 @@ const server = http.createServer(common.mustCall(function(req, res) {
 }));
 
 server.on('clientError', common.mustCall(function(err, socket) {
+  assert.strictEqual(err instanceof Error, true);
+  assert.strictEqual(err.code, 'HPE_INVALID_METHOD');
+  assert.strictEqual(err.bytesParsed, 1);
+  assert.strictEqual(err.message, 'Parse Error');
+  assert.strictEqual(err.rawPacket.toString(), 'Oopsie-doopsie\r\n');
+
   socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');
 
   server.close();