Unwind the rtc git pin: rtc + webrtc 0.21.0-rc.2 from crates.io - #169
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The lann/webrtc fork rev existed to carry one rtc-sctp fix no release had: an incoming stream reset discarded received-but-undelivered messages (lann/rtc#1; the receive-side loss of #125). Upstream fixed the same bug independently in webrtc-rs/rtc#200 (in rc.1+), by the RFC 6525 mechanism: the RECONFIG is answered "In Progress" while the stream still holds readable data, and the reset is re-run once the application drains it. The srflx source-address check (webrtc-rs/rtc#136) is in the series too, so nothing the pin carried is fork-only any more. API follow-through for the rc: - rtc threads a caller-supplied `now: Instant` through construction, description setters, and sends, and wraps `poll_read` output in `TaggedRTCMessage`; the guest peer passes `Instant::now()`, its clock already. - `SettingEngine` is immutable, built by a consuming `SettingEngineBuilder`, so `WebrtcCtx`'s hook becomes `Fn(SettingEngineBuilder) -> SettingEngineBuilder`; both hook sites (the demo host's loopback opt-in, the conformance driver's loopback / mDNS settings) follow. Exact `=` pins: the two crates release in lockstep and `webrtc` depends on the exact `rtc` it shipped with. Verified: just check; examples::test-webrtc-composed; examples::test-echo-remote-composed; just conformance (148 loopback + 156 interop results, 0 failing, both committed matrices unchanged). Closes #120.
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September 6, 2026 22:46
# Conflicts: # Cargo.toml
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Closes #120.
Why now
The
lann/webrtc@15755c6bpin existed to carry onertc-sctpfix no release had: an incoming stream reset discarded received-but-undelivered messages (lann/rtc#1, the receive-side loss of #125). Upstream fixed the same bug independently in webrtc-rs/rtc#200 (merged 2026-08-26, in rc.1+) — and by the mechanism RFC 6525 provides for it: the RECONFIG is answered In Progress while the stream still holds readable data, and the reset is re-run once the application drains it (retry_deferred_resets). The fork answered Success and deferred only the local teardown. The srflx source-address check (webrtc-rs/rtc#136) is in the series too, so nothing the pin carried is fork-only any more; lann/rtc#1 needs no upstreaming.0.21.0-rc.2(crates.io, 2026-09-04) is upstream master's current state; exact=pins because the two crates release in lockstep andwebrtcdepends on the exactrtcit shipped with.What changed in the rc that touches us
now: Instantis threaded throughRTCPeerConnectionBuilder::build,set_{local,remote}_description,send/send_text;poll_readyieldsTaggedRTCMessage. The guest peer passesInstant::now()— already its clock.SettingEngine→ consumingSettingEngineBuilder:WebrtcCtx's hook type becomesFn(SettingEngineBuilder) -> SettingEngineBuilder(public API change onwasmtime-webrtc-datachannels); both hook sites follow.opendeferred until DCEP ACK (rtc#171), SCTP stream id assigned only once the DTLS role is known — the RFC 8832 even/odd parity fix (rtc#199), zero-window deadlock at buffer-full tail (rtc#217), inbound channels gated on SCTP readiness (rtc#228), RFC 9260 initial RTO (rtc#226).Verification
just check(fmt, clippy on every target, WIT, 22 tests)just examples::test-webrtc-composed,just examples::test-echo-remote-composedjust conformance: 148 loopback + 156 interop results, 0 failing, both committed matrices byte-identicalshadow-lab.Automerge armed.