mirror of
https://github.com/pion/ice.git
synced 2026-04-23 00:27:06 +08:00
sirzooro
ceccc15191
This PR fixes two race conditions introduced by peer-reflexive candidate replacement and addresses a connectivity regression where an agent could transition from Connected to Disconnected/Failed shortly after replacement. ## Problems 1. Data race in candidate pair access: - `replaceRedundantPeerReflexiveCandidates` updated `pair.Remote` in place. - At the same time, hot-path reads (for example `CandidatePair.Write`) could read `pair.Remote` without synchronization. 2. Data race in remote candidate cache map: - `candidateBase.handleInboundPacket` (non-STUN path) read/wrote `remoteCandidateCaches` from recv loop goroutines. - Concurrent writes also happened from agent-loop code (`replaceRemoteCandidateCacheValues`). 3. Connectivity regression after replacement: - When replacing a selected pair's remote candidate (prflx -> signaled), the new candidate could have zero `LastReceived`/`LastSent`. - `validateSelectedPair` uses `selectedPair.Remote.LastReceived()`, which could cause quick `Connected -> Disconnected -> Failed` transitions. ## Root Cause Replacement logic preserved pair priority but mutated shared objects in place and did not preserve candidate activity timestamps across candidate object replacement. ## Fixes ### 1) Replace candidate pair objects instead of mutating `pair.Remote` - Added helper `replacePairRemote(pair, remote)` to clone pair state into a new `CandidatePair`. - Preserved pair fields and runtime stats: - `id`, role, state, nomination flags, binding counters. - RTT fields, packet/byte counters, request/response counters. - timestamp `atomic.Value` fields. - Replaced references in: - `a.checklist[i]` - `a.pairsByID[pair.id]` - If old pair was selected, published replacement via `a.setSelectedPair(replacement)`. ### 2) Serialize remote cache access on agent loop - Updated non-STUN path in `candidateBase.handleInboundPacket`: - Cache validation, remote candidate lookup, `seen(false)`, and cache insert now run inside `agent.loop.Run(...)`. - This removes concurrent map read/write between recv loop and agent-loop updates. ### 3) Preserve candidate activity on replacement - Added `copyCandidateActivity(dst, src)` to transfer: - `LastReceived` - `LastSent` - Applied before replacing references so selected-pair liveness checks remain stable.
68 lines
1.6 KiB
Go
68 lines
1.6 KiB
Go
// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
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// SPDX-License-Identifier: MIT
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package ice
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import (
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"net"
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"net/netip"
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)
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// CandidateServerReflexive ...
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type CandidateServerReflexive struct {
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candidateBase
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}
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// CandidateServerReflexiveConfig is the config required to create a new CandidateServerReflexive.
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type CandidateServerReflexiveConfig struct {
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CandidateID string
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Network string
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Address string
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Port int
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Component uint16
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Priority uint32
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Foundation string
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RelAddr string
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RelPort int
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}
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// NewCandidateServerReflexive creates a new server reflective candidate.
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func NewCandidateServerReflexive(config *CandidateServerReflexiveConfig) (*CandidateServerReflexive, error) {
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ipAddr, err := netip.ParseAddr(config.Address)
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if err != nil {
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return nil, err
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}
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networkType, err := determineNetworkType(config.Network, ipAddr)
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if err != nil {
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return nil, err
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}
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candidateID := config.CandidateID
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if candidateID == "" {
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candidateID = globalCandidateIDGenerator.Generate()
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}
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return &CandidateServerReflexive{
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candidateBase: candidateBase{
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id: candidateID,
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networkType: networkType,
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candidateType: CandidateTypeServerReflexive,
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address: config.Address,
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port: config.Port,
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resolvedAddr: &net.UDPAddr{
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IP: ipAddr.AsSlice(),
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Port: config.Port,
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Zone: ipAddr.Zone(),
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},
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component: config.Component,
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foundationOverride: config.Foundation,
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priorityOverride: config.Priority,
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relatedAddress: &CandidateRelatedAddress{
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Address: config.RelAddr,
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Port: config.RelPort,
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},
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},
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}, nil
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}
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