Add RemoteCandidateCache for better performance

Check sourceAddress from first packet validation of STUNTraffic.
If validation is true, store it in the cache.
Use cache for performance.

addr.go

@@ -3,7 +3,9 @@
 
 package ice
 
-import "net"
+import (
+	"net"
+)
 
 func parseMulticastAnswerAddr(in net.Addr) (net.IP, bool) {
 	switch addr := in.(type) {
@@ -49,3 +51,21 @@ func addrEqual(a, b net.Addr) bool {
 
 	return aType == bType && aIP.Equal(bIP) && aPort == bPort
 }
+
+// AddrPort is  an IP and a port number.
+type AddrPort [18]byte
+
+func toAddrPort(addr net.Addr) AddrPort {
+	var ap AddrPort
+	switch addr := addr.(type) {
+	case *net.UDPAddr:
+		copy(ap[:16], addr.IP.To16())
+		ap[16] = uint8(addr.Port >> 8)
+		ap[17] = uint8(addr.Port)
+	case *net.TCPAddr:
+		copy(ap[:16], addr.IP.To16())
+		ap[16] = uint8(addr.Port >> 8)
+		ap[17] = uint8(addr.Port)
+	}
+	return ap
+}

agent.go

@@ -1138,19 +1138,18 @@ func (a *Agent) handleInbound(m *stun.Message, local Candidate, remote net.Addr)
 
 // validateNonSTUNTraffic processes non STUN traffic from a remote candidate,
 // and returns true if it is an actual remote candidate
-func (a *Agent) validateNonSTUNTraffic(local Candidate, remote net.Addr) bool {
-	var isValidCandidate uint64
+func (a *Agent) validateNonSTUNTraffic(local Candidate, remote net.Addr) (Candidate, bool) {
+	var remoteCandidate Candidate
 	if err := a.run(local.context(), func(ctx context.Context, agent *Agent) {
-		remoteCandidate := a.findRemoteCandidate(local.NetworkType(), remote)
+		remoteCandidate = a.findRemoteCandidate(local.NetworkType(), remote)
 		if remoteCandidate != nil {
 			remoteCandidate.seen(false)
-			atomic.AddUint64(&isValidCandidate, 1)
 		}
 	}); err != nil {
 		a.log.Warnf("failed to validate remote candidate: %v", err)
 	}
 
-	return atomic.LoadUint64(&isValidCandidate) == 1
+	return remoteCandidate, remoteCandidate != nil
 }
 
 // GetSelectedCandidatePair returns the selected pair or nil if there is none

candidate_base.go

@@ -41,6 +41,8 @@ type candidateBase struct {
 
 	foundationOverride string
 	priorityOverride   uint32
+
+	remoteCandidateCaches map[AddrPort]Candidate
 }
 
 // Done implements context.Context
@@ -234,6 +236,21 @@ func (c *candidateBase) recvLoop(initializedCh <-chan struct{}) {
 	}
 }
 
+func (c *candidateBase) validateSTUNTrafficCache(addr net.Addr) bool {
+	if candidate, ok := c.remoteCandidateCaches[toAddrPort(addr)]; ok {
+		candidate.seen(false)
+		return true
+	}
+	return false
+}
+
+func (c *candidateBase) addRemoteCandidateCache(candidate Candidate, srcAddr net.Addr) {
+	if c.validateSTUNTrafficCache(srcAddr) {
+		return
+	}
+	c.remoteCandidateCaches[toAddrPort(srcAddr)] = candidate
+}
+
 func (c *candidateBase) handleInboundPacket(buf []byte, srcAddr net.Addr) {
 	a := c.agent()
 
@@ -259,9 +276,13 @@ func (c *candidateBase) handleInboundPacket(buf []byte, srcAddr net.Addr) {
 		return
 	}
 
-	if !a.validateNonSTUNTraffic(c, srcAddr) { //nolint:contextcheck
-		a.log.Warnf("Discarded message from %s, not a valid remote candidate", c.addr())
-		return
+	if !c.validateSTUNTrafficCache(srcAddr) {
+		remoteCandidate, valid := a.validateNonSTUNTraffic(c, srcAddr) //nolint:contextcheck
+		if !valid {
+			a.log.Warnf("Discarded message from %s, not a valid remote candidate", c.addr())
+			return
+		}
+		c.addRemoteCandidateCache(remoteCandidate, srcAddr)
 	}
 
 	// Note: This will return packetio.ErrFull if the buffer ever manages to fill up.

candidate_host.go

@@ -37,14 +37,15 @@ func NewCandidateHost(config *CandidateHostConfig) (*CandidateHost, error) {
 
 	c := &CandidateHost{
 		candidateBase: candidateBase{
-			id:                 candidateID,
-			address:            config.Address,
-			candidateType:      CandidateTypeHost,
-			component:          config.Component,
-			port:               config.Port,
-			tcpType:            config.TCPType,
-			foundationOverride: config.Foundation,
-			priorityOverride:   config.Priority,
+			id:                    candidateID,
+			address:               config.Address,
+			candidateType:         CandidateTypeHost,
+			component:             config.Component,
+			port:                  config.Port,
+			tcpType:               config.TCPType,
+			foundationOverride:    config.Foundation,
+			priorityOverride:      config.Priority,
+			remoteCandidateCaches: map[AddrPort]Candidate{},
 		},
 		network: config.Network,
 	}

candidate_peer_reflexive.go

@@ -59,6 +59,7 @@ func NewCandidatePeerReflexive(config *CandidatePeerReflexiveConfig) (*Candidate
 				Address: config.RelAddr,
 				Port:    config.RelPort,
 			},
+			remoteCandidateCaches: map[AddrPort]Candidate{},
 		},
 	}, nil
 }

candidate_relay.go

@@ -63,6 +63,7 @@ func NewCandidateRelay(config *CandidateRelayConfig) (*CandidateRelay, error) {
 				Address: config.RelAddr,
 				Port:    config.RelPort,
 			},
+			remoteCandidateCaches: map[AddrPort]Candidate{},
 		},
 		relayProtocol: config.RelayProtocol,
 		onClose:       config.OnClose,

candidate_server_reflexive.go

@@ -55,6 +55,7 @@ func NewCandidateServerReflexive(config *CandidateServerReflexiveConfig) (*Candi
 				Address: config.RelAddr,
 				Port:    config.RelPort,
 			},
+			remoteCandidateCaches: map[AddrPort]Candidate{},
 		},
 	}, nil
 }