HydarTURN

HydarTURN is a lightweight and embeddable Java implementation of the STUN/TURN protocol.
It runs a single instance bound to the local wildcard IP. Allocations will use the same local address and incrementally generated ports.
Features:

• STUN: binding requests/responses
• TURN: Allocations
• Message integrity and fingerprinting
• Authentication(authenticator can only be provided programatically for now)
• Permissions and nonces(associated with an allocation)
• Relaying(DATA/SEND)
• Channel binding and channel relaying(CHANNELBIND)
• Support for both UDP & TCP instances

These features are sufficient to route WebRTC voice and video calls from most browsers. To ensure TURN is being used when testing, set ice transport type as 'relay'.
Unimplemented features:

• Port reservations and dont-fragment requests are ignored, and the new STUN features added in RFC 8489(sha256 message integrity) are not supported.
• Only one authentication realm, "hydar", is ever supported.
• The third protocol allowed for TURN relaying, TURN-over-TLS, is not supported. Note that this doesn't mean calls are insecure, since WebRTC encrypts its own messages regardless of the transport.

Implementation

The implementation consists of a single source file, xyz.hydar.turn.HydarTURN.

HydarTURN was designed for embedding in hydar.xyz, another open source project.