On Windows, configuring a named pipe server with pipe_mode will force ServerOptions::reject_remote_clients as false.

This drops any intended explicit configuration for the reject_remote_clients that may have been set as true previously.

The default setting of reject_remote_clients is normally true meaning the default is also overridden as false.

Workarounds

Ensure that pipe_mode is set first after initializing a ServerOptions. For example:

let mut opts = ServerOptions::new();
opts.pipe_mode(PipeMode::Message);
opts.reject_remote_clients(true);

Impact

When using tonic::transport::Server there is a remote DoS attack that can cause the server to exit cleanly on accepting a tcp/tls stream. This can be triggered via causing the accept call to error out with errors there were not covered correctly causing the accept loop to exit.

More information can be found here

Patches

Upgrading to tonic 0.12.3 and above contains the fix.

Workarounds

A custom accept loop is a possible workaround.