WIP

peer/mcreader.go

@@ -1,47 +1,66 @@
 package peer
 
 import (
+	"encoding/binary"
+	"fmt"
 	"log"
 	"net"
+	"net/netip"
 	"time"
+
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 )
 
-func RunMCReader(g Globals) {
+func RunMCReader(g Globals, hp *HolePunch, netName string) {
 	for {
-		runMCReaderInner(g)
+		if err := runMCReaderInner(g, hp, netName); err != nil {
+			log.Printf("[MCReader] %v", err)
+		}
 		time.Sleep(broadcastErrorTimeoutInterval)
 	}
 }
 
-func runMCReaderInner(g Globals) {
-	var (
-		buf  = make([]byte, bufferSize)
-		logf = func(s string, args ...any) {
-			log.Printf("[MCReader] "+s, args...)
-		}
-	)
-
+func runMCReaderInner(g Globals, hp *HolePunch, netName string) error {
 	conn, err := net.ListenMulticastUDP("udp", nil, multicastAddr)
 	if err != nil {
-		logf("Failed to bind to multicast address: %v", err)
+		return fmt.Errorf("bind: %w", err)
+	}
+	defer conn.Close()
+
+	buf := make([]byte, 64)
+	for {
+		conn.SetReadDeadline(time.Now().Add(32 * time.Second))
+		n, src, err := conn.ReadFromUDPAddrPort(buf)
+		if err != nil {
+			return fmt.Errorf("read: %w", err)
+		}
+		if n != beaconLen {
+			continue
+		}
+		handleBeacon(g, hp, netName, buf[:n], src)
+	}
+}
+
+func handleBeacon(g Globals, hp *HolePunch, netName string, beacon []byte, src netip.AddrPort) {
+	peerIPByte := beacon[0]
+	if peerIPByte == g.LocalPeerIP {
 		return
 	}
 
-	for {
-		conn.SetReadDeadline(time.Now().Add(32 * time.Second))
-		n, remoteAddr, err := conn.ReadFromUDPAddrPort(buf[:bufferSize])
-		if err != nil {
-			logf("Failed to read from UDP port): %v", err)
+	pubKey, err := wgtypes.NewKey(beacon[1:33])
+	if err != nil {
+		return
+	}
+
+	// Skip relay peers: probing would replace their /24 AllowedIPs with empty.
+	if state, err := loadNetworkState(netName); err == nil {
+		if p := state.Peers[peerIPByte]; p != nil && p.Relay {
 			return
 		}
-
-		buf = buf[:n]
-		h, ok := headerFromLocalDiscoveryPacket(buf)
-		if !ok {
-			logf("Failed to open discovery packet?")
-			continue
-		}
-
-		g.RemotePeers[h.SourceIP].Load().HandleLocalDiscoveryPacket(h, remoteAddr, buf)
 	}
+
+	wgPort := binary.BigEndian.Uint16(beacon[33:35])
+	endpoint := netip.AddrPortFrom(src.Addr().Unmap(), wgPort)
+
+	hp.OnEndpointLearned(peerIPByte, pubKey, endpoint, false)
 }