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perf(relay): cache resolved UDP destinations with TTL

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This commit is contained in:
Laurence
2026-03-12 12:54:59 +00:00
parent b9261b8fea
commit b118fef265
1 changed files with 44 additions and 4 deletions
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48
relay/relay.go
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@@ -153,6 +153,9 @@ type UDPProxyServer struct {
// Communication pattern tracking for rebuilding sessions
// Key format: "clientIP:clientPort-destIP:destPort"
commPatterns sync.Map
// Cache for resolved UDP addresses to avoid per-packet DNS lookups
// Key: "ip:port" string, Value: *net.UDPAddr
addrCache sync.Map
// ReachableAt is the URL where this server can be reached
ReachableAt string
}
@@ -416,6 +419,43 @@ func extractWireGuardIndices(packet []byte) (uint32, uint32, bool) {
return 0, 0, false
}
// cachedAddr holds a resolved UDP address with TTL
type cachedAddr struct {
addr *net.UDPAddr
expiresAt time.Time
}
// addrCacheTTL is how long resolved addresses are cached before re-resolving
const addrCacheTTL = 5 * time.Minute
// getCachedAddr returns a cached UDP address or resolves and caches it.
// This avoids per-packet DNS lookups which are a major throughput bottleneck.
func (s *UDPProxyServer) getCachedAddr(ip string, port int) (*net.UDPAddr, error) {
key := fmt.Sprintf("%s:%d", ip, port)
// Check cache first
if cached, ok := s.addrCache.Load(key); ok {
entry := cached.(*cachedAddr)
if time.Now().Before(entry.expiresAt) {
return entry.addr, nil
}
// Cache expired, delete and re-resolve
s.addrCache.Delete(key)
}
// Resolve and cache
addr, err := net.ResolveUDPAddr("udp", key)
if err != nil {
return nil, err
}
s.addrCache.Store(key, &cachedAddr{
addr: addr,
expiresAt: time.Now().Add(addrCacheTTL),
})
return addr, nil
}
// Updated to handle multi-peer WireGuard communication
func (s *UDPProxyServer) handleWireGuardPacket(packet []byte, remoteAddr *net.UDPAddr) {
if len(packet) == 0 {
@@ -450,7 +490,7 @@ func (s *UDPProxyServer) handleWireGuardPacket(packet []byte, remoteAddr *net.UD
logger.Debug("Forwarding handshake initiation from %s (sender index: %d) to peers %v", remoteAddr, senderIndex, proxyMapping.Destinations)
for _, dest := range proxyMapping.Destinations {
destAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", dest.DestinationIP, dest.DestinationPort))
destAddr, err := s.getCachedAddr(dest.DestinationIP, dest.DestinationPort)
if err != nil {
logger.Error("Failed to resolve destination address: %v", err)
continue
@@ -486,7 +526,7 @@ func (s *UDPProxyServer) handleWireGuardPacket(packet []byte, remoteAddr *net.UD
// Forward the response to the original sender
for _, dest := range proxyMapping.Destinations {
destAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", dest.DestinationIP, dest.DestinationPort))
destAddr, err := s.getCachedAddr(dest.DestinationIP, dest.DestinationPort)
if err != nil {
logger.Error("Failed to resolve destination address: %v", err)
continue
@@ -543,7 +583,7 @@ func (s *UDPProxyServer) handleWireGuardPacket(packet []byte, remoteAddr *net.UD
// No known session, fall back to forwarding to all peers
logger.Debug("No session found for receiver index %d, forwarding to all destinations", receiverIndex)
for _, dest := range proxyMapping.Destinations {
destAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", dest.DestinationIP, dest.DestinationPort))
destAddr, err := s.getCachedAddr(dest.DestinationIP, dest.DestinationPort)
if err != nil {
logger.Error("Failed to resolve destination address: %v", err)
continue
@@ -571,7 +611,7 @@ func (s *UDPProxyServer) handleWireGuardPacket(packet []byte, remoteAddr *net.UD
// Forward to all peers
for _, dest := range proxyMapping.Destinations {
destAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", dest.DestinationIP, dest.DestinationPort))
destAddr, err := s.getCachedAddr(dest.DestinationIP, dest.DestinationPort)
if err != nil {
logger.Error("Failed to resolve destination address: %v", err)
continue