sip: redirect RTP destination on re-INVITE port change#728
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VictorUvarov wants to merge 12 commits into
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sip: redirect RTP destination on re-INVITE port change#728VictorUvarov wants to merge 12 commits into
VictorUvarov wants to merge 12 commits into
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When a carrier sends a re-INVITE with a new SDP offer containing a different RTP destination address/port, update the media port to send packets to the new destination. This fixes mid-call carrier port changes which were previously ignored. The fix parses the re-INVITE SDP offer body and calls UpdateRemote() to change the RTP destination before accepting the re-INVITE. Parsing errors are logged but don't prevent accepting the re-INVITE.
…INVITE test - In MediaPort.UpdateRemote(), add !addr.Addr().IsUnspecified() guard to reject RFC 3264 §8.4 call-hold form (c=0.0.0.0 with non-zero port). netip.AddrPort with unspecified address is IsValid() == true, so prior guard missed it. - Add TestMediaPortUpdateRemote case verifying 0.0.0.0:N is a no-op. - Add TestReinvite/inbound/no_body subtest: verify a body-less re-INVITE leaves RemoteAddr unchanged (guards against offer-in-ACK / no-SDP-body cases).
- Add sdpBodyFromRequest helper to guard updateRemoteFromSDP against non-SDP content types; avoids spurious warn log on e.g. application/json - Derive expected RemoteAddr in tests from newOffer.Addr instead of a hardcoded string literal - Add outbound/no_body test symmetric to inbound/no_body; use call.NewRequest(INVITE) in both no_body cases for a truly body-less re-INVITE (Invite(nil) silently generates an SDP offer)
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udpConn.SetDst logged a nil *netip.AddrPort as "prev" on the first call
(before any destination was stored). The logger called .String() on the
nil pointer, causing a panic. Replace with the zero value netip.AddrPort{}.
Same class of bug as SetDst: udpConn.Read logged a nil *netip.AddrPort
as "prev" on the first packet received. Replace with netip.AddrPort{}.
req.ContentType() returns *ContentTypeHeader (a Stringer). When there is no body the header is nil; fmt calls String() on the typed nil pointer, causing a recovered panic that tparse reports as PANIC. Drop content-type from the reinvite log calls — content-length already indicates whether a body is present.
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #728 +/- ##
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+ Coverage 65.25% 65.85% +0.60%
==========================================
Files 51 41 -10
Lines 6588 7744 +1156
==========================================
+ Hits 4299 5100 +801
- Misses 1915 2175 +260
- Partials 374 469 +95 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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The "setting media destination/source" branch fires when prev is nil (no previous value). Logging prev as an empty AddrPort was misleading.
dennwc
reviewed
Jun 23, 2026
dennwc
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Looks good in general, thank you! A few small changes needed:
Use the call's own CodecSet instead of GlobalCodecs() when parsing re-INVITE SDP. Add updateRemoteFromSDP methods on inboundCall (holds mmu) and outboundCall to make safe access to media explicit and encapsulated. Store mediaCodecs on inboundCall alongside media under mmu in runMediaConn.
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Problem
When a SIP carrier sends a mid-call re-INVITE with a new RTP port (e.g. after a NAT rebind or media relay failover), LiveKit SIP was responding 200 OK but continuing to send RTP to the stale address — violating RFC 3264 §8, which requires the answerer to direct media to the address/port in the new offer.
Closes #661
What changed
pkg/sip/media_port.go: two new methods onMediaPort:UpdateRemote: atomically redirects the RTP destination.RemoteAddr: read accessor, used in tests.pkg/sip/inbound.go: both re-INVITE paths now parse the SDP body and callUpdateRemotebefore responding 200 OK.Tests
pkg/sip/media_port_test.go—TestMediaPortUpdateRemotecovers thehappy path, the zero-value no-op, and the unspecified-addr no-op.pkg/sip/signaling_test.go—TestReinviteextended:inbound/normal: assertsRemoteAddr()changes after a re-INVITE.outbound/normal: same for the outbound path.inbound/no_body: asserts a body-less re-INVITE leavesRemoteAddr()unchanged.Unit tests
Integration tests
go test ./pkg/sip/... -count=1Thought process summary
The root cause was a one-liner gap: the re-INVITE handler called AcceptAsKeepAlive (200 OK) but never forwarded the new c=/m= address to the RTP layer. The SDP body already contained the new addr+port as desc.Addr after ParseWith — nothing needed to be renegotiated, just the destination pointer swapped.
The tricky edge case was RFC 3264 §8.4 call-hold, where c=0.0.0.0 signals hold and
netip.MustParseAddrPort("0.0.0.0:N").IsValid()returnstrue. A plainIsValid()guard would have let hold re-INVITEs overwrite the real destination with the zero address. The!addr.Addr().IsUnspecified()check inside UpdateRemote blocks that.