librice

Repository containing an (sans-IO) implementation of ICE (RFC8445) protocol written in the Rust programming language. A C API interface is currently also provided for librice-proto and librice-io.

Current status

The current status is that there is enough of the implementation to sucessfully communicate with STUN/TURN servers and/or a browser (Chrome or Firefox) in a WebRTC scenario. The STUN implementation is relatively mature. More work is needed on the ICE layer for efficiency and API experience. Initial TURN support has been implemented and some TURN-related RFCs are currently in progress. Supporting more scenarios is part of the near and long term future roadmap.

Why sans-io?

A few reasons: reusability, testability, and composability.

Without being bogged down in the details of how IO happens, the same sans-IO implementation can be used without prescribing the IO pattern that an application must follow. Instead, the application (or parent library) has much more freedom in how bytes are transferred between peers. It is possible to use a sans-IO library in either a synchronous environment or within an asynchronous runtime.

A sans-IO design also allows easy testing of any specific state the sans-IO implementation might find itself in. Combined with a comprehensive test-suite, this provides assurance that the implementation behaves as expected under all circumstances.

For other examples of sans-IO implementations, take a look at:

• stun-proto: A sans-IO implementation of a STUN agent (client or server).
• turn-proto: A sans-IO implementation of a TURN client or server.
• Quinn: A pure Rust async-compatible implementation of QUIC.
• https://sans-io.readthedocs.io/

Relevant standards

• RFC5245: Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols
• RFC5389: Session Traversal Utilities for NAT (STUN)
• RFC5766: Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)
• RFC5769: Test Vectors for Session Traversal Utilities for NAT (STUN)
• RFC6062: Traversal Using Relays around NAT (TURN) Extensions for TCP Allocations
• RFC6156: Traversal Using Relays around NAT (TURN) Extension for IPv6
• RFC6544: TCP Candidates with Interactive Connectivity Establishment (ICE)
• RFC7675: Session Traversal Utilities for NAT (STUN) Usage for Consent Freshness
• RFC8445: Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal
• RFC8489: Session Traversal Utilities for NAT (STUN)
• RFC8656: Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)
• RFC8838: Trickle ICE: Incremental Provisioning of Candidates for the Interactive Connectivity Establishment (ICE) Protocol

Structure

librice-proto

The sans-IO implementation of the ICE (RFC8445) protocol. Contains no IO code whatsover.

librice

An async implementation of ICE (RFC8445) built using librice-proto. Currently uses async-std however a tokio (or mio) implementation is planned.

librice-io

An optional library exposing a C interface for handling IO using Rust's network primitives UdpSocket, and TcpStream. Uses a single dedicated thread for handling IO wakeups. It is not required for implementation.

TODO

• RFC6062
• RFC6156
• RFC7675
• RFC8656