Demo of grpc-java large header bug #4284

This repo provides a minimal demonstration of grpc-java issue #4284 and netty issue #7825.

To reproduce the issue, you need to run an Envoy proxy between a grpc server and a java client.

This demo uses grpc's HelloWorld examples as a base, with these notable changes:

1. The example server was modified to advertise a large maximum accepted header size (100kB).
2. The example client was modified to send a 9kB header - larger than the default max size of 8kB, but smaller than the max advertised by the server.
3. An envoy proxy server is set up to act as a middle man between the server and client. The envoy server advertises no max header size, which according to the HTTP/2 spec means that the server is willing to accept arbitrarily long headers.

Setup

1. Build the java server and client as directed in the java folder's README.

2. Install Docker as directed in the envoy folder's README.

To reproduce the bug:

1. Start the envoy proxy server in one terminal. The proxy listens on port 40051 and redirects to port 50051:

   envoy/envoy.sh
   

2. Start the java server in another terminal. The server listens on port 50051:

   java/build/install/examples/bin/hello-world-server
   

3. Run the java client in a third terminal, pointing it to the proxy port:

   java/build/install/examples/bin/hello-world-client 40051
   

You should see error:

WARNING: RPC failed: Status{code=INTERNAL, description=http2 exception, cause=io.netty.handler.codec.http2.Http2Exception$HeaderListSizeException: Header size exceeded max allowed size (8192)
...

To show that the error does not occur on a direct client->server connection:

1. Start the java server in one terminal:

   java/build/install/examples/bin/hello-world-server
   

2. Run the java client in another terminal, pointing it to the server port:

   java/build/install/examples/bin/hello-world-client 50051
   

You should see successful INFO logs from both the client and server.

Python client doesn't have the error:

For good measure you can see that a python client does not have the same error.

1. Run the python client. It should work for either port:

   python python/greeter_client.py 40051
   python python/greeter_client.py 50051