docs, errors, http: disallow setEncoding on incoming packets

added ERR_HTTP_INCOMING_SOCKET_ENCODING error and error docs
throw ERR_HTTP_INCOMING_SOCKET_ENCODING error when incoming request
socket encoding is manipulated

error report detailed in nodejs#18118

Fixes: nodejs#18118
Ref: nodejs#18178

doc/api/errors.md

@@ -794,6 +794,12 @@ An invalid symlink type was passed to the [`fs.symlink()`][] or
 
 An attempt was made to add more headers after the headers had already been sent.
 
+<a id="ERR_HTTP_INCOMING_SOCKET_ENCODING"></a>
+### ERR_HTTP_INCOMING_SOCKET_ENCODING
+
+An attempt was made to manipulate the encoding of an incoming request packet.
+This is not allowed (RFC2616).
+
 <a id="ERR_HTTP_INVALID_HEADER_VALUE"></a>
 ### ERR_HTTP_INVALID_HEADER_VALUE
 

lib/_http_server.js

@@ -685,7 +685,7 @@ function onSocketPause() {
 }
 
 function socketSetEncoding() {
-  throw new errors.Error('ERR_METHOD_NOT_IMPLEMENTED', 'setEncoding');
+  throw new errors.Error('ERR_HTTP_INCOMING_SOCKET_ENCODING', 'setEncoding');
 }
 
 function unconsume(parser, socket) {

lib/internal/errors.js

@@ -762,6 +762,9 @@ E('ERR_HTTP2_STREAM_SELF_DEPENDENCY',
 E('ERR_HTTP2_UNSUPPORTED_PROTOCOL', 'protocol "%s" is unsupported.', Error);
 E('ERR_HTTP_HEADERS_SENT',
   'Cannot %s headers after they are sent to the client', Error);
+E('ERR_HTTP_INCOMING_SOCKET_ENCODING',
+  'Incoming socket encoding is not allowed (RFC 2616)',
+  Error);
 E('ERR_HTTP_INVALID_HEADER_VALUE',
   'Invalid value "%s" for header "%s"', TypeError);
 E('ERR_HTTP_INVALID_STATUS_CODE', 'Invalid status code: %s', RangeError);

test/parallel/test-http-socket-encoding-error.js

@@ -8,7 +8,7 @@ const server = http.createServer().listen(0, connectToServer);
 server.on('connection', (socket) => {
   common.expectsError(() => socket.setEncoding(''),
                       {
-                        code: 'ERR_METHOD_NOT_IMPLEMENTED',
+                        code: 'ERR_HTTP_INCOMING_SOCKET_ENCODING',
                         type: Error
                       });