# porter

porter is a gateway experiment for passing around live sockets between processes. the porter is merely a shim that hands off connections to processes without dealing with any state.

## usage

generate a certificate and private key with `openssl`, in pem format, and include them in `./certs`. naming convention: server.*.pem.

start the porter server, which runs a shim on port `4848`:

```
cargo run --bin porter
```

run the receiving client that receives on port `4849`:

```
cargo run --bin client -- receive
```

start both processes:

```
# for blue
cargo run --bin process -- blue
```

```
# for green
cargo run --bin process -- green
```

execute the sending client:

```
cargo run --bin client -- send
```

watch as the TCP connection is passed from the sending client to the porter shim, which feeds the inbound FD to Blue.
the Blue process terminates TLS and feeds the request to the receiving client.
on SIGINT/SIGTERM, the Blue process passes the existing inbound/outbound FDs to the Green process. kTLS is used to preserve the TLS session state across the handoff.
Green continues proxying existing connections and polls the shim for new connections.

## dev environment

I advice you set up direnv in order to use the Nix flake if you're on NixOS with LLD linking enabled.

for your kernel, enable `tls`. in NixOS it's done via adding the following to your configuration:

```
boot.kernelModules = [ "tls" ];
```