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fix: CANCEL a dropped INVITE after its first provisional response (rebase of #168) - #171
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shenjinti merged 1 commit intoOct 6, 2026
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When the do_invite future is dropped before any provisional response, the guard drops the INVITE transaction and sends nothing. The INVITE may still have reached the callee: its 180 gets no CANCEL, and a 2xx is neither ACKed nor ended, so the callee keeps ringing or answers into dead air. A CANCEL must not be sent before a provisional response; the UAC has to wait for one and CANCEL then (RFC 3261 §9.1). Keep the INVITE transaction, without retransmissions, until its first response (up to 64*T1): on a provisional, cancel it as a call dropped while ringing; on a 2xx, ACK it and send a BYE; any other final response is ACKed by the transaction. Terminated(UacCancel) is still reported at once, and nothing is sent when no response arrives.
This was referenced Oct 6, 2026
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Ships this round on top of 0.7.0: proxy-mode auto_ack_2xx (#146/#172), ACK CSeq routing (#155/#170/#172), digest auth_username (#153), dead stream retirement (#161), remote-ack getter (#157), UAS ACK timeout → BYE (#149/#169), RFC 6026 Accepted state + Timer L/M with documented deviations (#164/#169), CANCEL/2xx race handling (#162/#171), in-dialog Via transport (#163), flow-reuse and ACK hardening tests.
This was referenced Oct 7, 2026
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Rebase of #168 by @tgeorge06, closes #166.
DialogGuardForUnconfirmed::dropno longer discards the INVITE transaction while the dialog is stillCalling: the transaction is kept for one response window (64*T1). A provisional response triggers the existing CANCEL flow (RFC 3261 §9.1 — no CANCEL before a provisional); a 2xx that arrives with no provisional gets the end-to-end ACK and a BYE (RFC 3261 §13.2.2.4, §15, RFC 5407 §3.1.2 — same treatment as the #162 CANCEL/2xx race); a non-2xx final gets its ACK. Nothing is sent while no response has arrived.Applied cleanly on the merged RFC 6026 state machine (#164/#169). Local verification: 380 lib + 65 doc tests green across repeated runs, fmt clean. The PR's #166 reproduction tests (180 → CANCEL; 200 → ACK+BYE; 486 → ACK) pass.