GitHub - openpcc/ohttp: Oblivious HTTP in golang

OHTTP - Oblivious HTTP Client and Gateway written in Go

This package implements OHTTP in Go. It provides both a Transport (Client) and a Gateway.

ohttp is a Go package that provides an Oblivious HTTP (OHTTP) client and Gateway as specified in RFC 9458 and draft-ietf-ohai-chunked-ohttp-03.

Features

• Easy to use:
  • The Transport implements http.RoundTripper and can be plugged into a regular *http.Client. No need to adapt the rest of your app to send requests over OHTTP.
  • The Gateway can be used as a Middleware to wrap an existing http.Handler. The handler can speak regular HTTP while the middleware translates to OHTTP.
• Supports both unchunked (known length) and unchunked (unknown length) requests/responses.
• Defaults to bhttp encoding but accepts custom encodings.
• Overwrite every aspect of the roundtrip via custom encodings.

On OHTTP relays

An OHTTP Relay sits between an OHTTP Client and a Gateway. The relay keeps the identity of clients from the Gateway. For OHTTP to function as a system, it is fundamental that the relay is ran by a third party.

This package does not include a relay and assumes you have a third party relay in production environments. Cloudflare, Fastly and oblivious.network all offer OHTTP Relays as a service.

If you need a fake relay for local testing we advise you to use a general purpose proxy like httputil.ReverseProxy. This won't provide any anonymity, but your requests will at least follow a similar path.

Real world OHTTP Relays can be more constrained than a general purpose proxy, so be sure to verify the constraints on the relay you're planning to use.

Gateway as a dedicated server

The Gateway can be run in two ways:

• Combined Gateway and target resource in a single server.
• Dedicated Gateway and target resource servers.

The Gateway can be combined with the httputil.ReverseProxy to redirect requests to the target resource server. See the example below.

// Create the gateway and wrap the handler in its middleware.
gateway, err := ohttp.NewGateway(keyPair)
if err != nil {
  log.Fatalf("failed to create gateway: %v", err)
}

// Create a proxy that redirects requests to an external URL.
targetURL, err := url.Parse("https://example.com")
if err != nil {
  log.Fatalf("failed to parse url: %v", err)
}

proxy := httputil.NewSingleHostReverseProxy(targetURL)

// Wrap the proxy in the ohttp middleware.
h := ohttp.Middleware(gateway, http.HandlerFunc(proxy))

// h can now be used as the handler in a http.Server.

The above example only redirects to a single host (example.com). If you want the gateway to redirect to multiple hosts, and want the client to provide the hostname, look into the ohttp.NewHostnameAllowlist and ohttp.WithRequestValidator functions.

Example: Client and service over OHTTP

See examples/README.md for a local example that runs both the Client, the Gateway and a fake relay.

Comparison to alternative packages

Below we compare the features of this package to two other Go OHTTP packages.

chris-wood/ohttp-go

A great reference implementation by one of the authors of the OHTTP RFC. It's a library that provides both a client and a gateway.

cloudflare/privacy-gateway-server-go

A command that wraps the chris-wood/ohttp-go to provide a gateway you can run as a dedicated server. Since this is a command, we'll compare it to the recommended way to run the openpcc/ohttp Gateway as a dedicated server.

Found a security issue?

Reach out to security@confidentsecurity.com.

Development

Run tests with go test ./...

Run the examples with go run ./examples/client etc.

License

This project is licensed under the Apache License 2.0.

Contributing

For guidelines on contributing to this project, please see CONTRIBUTING.md.