rsrt

SRT (Secure Reliable Transport) protocol library in pure Rust — no C dependencies, async (tokio). Live transmission mode over UDP with TSBPD (timestamp-based packet delivery) including clock-drift compensation, ARQ (ACK/NAK/retransmission), too-late packet drop, LiveCC send-rate pacing, and HaiCrypt AES-128/192/256-CTR encryption with passphrase key exchange and in-stream key refresh. Caller and listener modes, HSv5 handshake.

The implementation was written from the protocol specification, IETF draft draft-sharabayko-srt-01. Interoperability with libsrt 1.4.4 (srt-live-transmit) is covered by the test suite in both directions.

Out of scope:

• rendezvous mode
• file/messaging mode
• AES-GCM,
• bonding/groups
• packet filter/FEC
• IPv6

Usage

Receiving (caller):

let mut sock = rsrt::SrtSocket::connect("127.0.0.1:9000", rsrt::SrtOptions::default()).await?;
while let Some(payload) = sock.recv().await? {
    // one live-mode message, e.g. up to 7 MPEG-TS packets
}

Sending (listener):

let mut listener = rsrt::SrtListener::bind("0.0.0.0:9000", rsrt::SrtOptions::default()).await?;
let (sock, peer) = listener.accept().await?;
sock.send(b"...").await?;

Tunables (latency, StreamID, passphrase/key length, bandwidth/pacing, buffer sizes, timeouts) live in SrtOptions; defaults follow libsrt 1.4.4 live mode.

Runnable examples: recv writes stream payloads to a file or stdout, send pushes a file (or stdin) at a steady bitrate. Both accept srt://host:port (caller) or srt://:port (listener) URLs with ?latency=<ms>, ?streamid=<s>, ?passphrase=<pw> parameters:

cargo run --example recv -- 'srt://:9000' out.ts
cargo run --example send -- in.ts 'srt://127.0.0.1:9000?rate=8'

Internals

Sans-I/O core: the wire codec, HaiCrypt engine, and connection state machine are pure and clock-driven, with tokio plumbing only at the crate root. See ARCHITECTURE.md for the layer map. cargo test runs unit tests, sans-I/O simulations, real-socket loopback and lossy-proxy suites; interop tests against srt-live-transmit run when it is installed and are skipped otherwise.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.