fix: 添加relay日志

cmd/internal/transport/kcp.go

@@ -196,15 +196,26 @@ func generateKCPConversationID() (uint32, error) {
 	return convID, nil
 }
 
-func listenKCPPacketConn(listenAddr, bindDevice string, logger KCPPacketDebugLogger, nodeRole, nodeID string) (net.PacketConn, error) {
+// ResolveUDPListenConfig parses a UDP listen address and returns the socket
+// family that should be used for binding it.
+func ResolveUDPListenConfig(listenAddr string) (string, *net.UDPAddr, error) {
 	udpAddr, err := net.ResolveUDPAddr("udp", listenAddr)
+	if err != nil {
+		return "", nil, fmt.Errorf("transport: resolve udp listen addr %s: %w", listenAddr, err)
+	}
+
+	return udpListenNetwork(udpAddr), udpAddr, nil
+}
+
+func listenKCPPacketConn(listenAddr, bindDevice string, logger KCPPacketDebugLogger, nodeRole, nodeID string) (net.PacketConn, error) {
+	network, udpAddr, err := ResolveUDPListenConfig(listenAddr)
 	if err != nil {
 		return nil, fmt.Errorf("transport: resolve kcp listen addr %s: %w", listenAddr, err)
 	}
 
-	rawConn, err := listenUDPConn("udp", udpAddr, bindDevice)
+	rawConn, err := listenUDPConn(network, udpAddr, bindDevice)
 	if err != nil {
-		return nil, fmt.Errorf("transport: listen udp for kcp on %s: %w", listenAddr, err)
+		return nil, fmt.Errorf("transport: listen %s for kcp on %s: %w", network, udpListenAddr(udpAddr), err)
 	}
 
 	packetConn, err := newKCPPacketConn(rawConn, logger, nodeRole, nodeID)
@@ -280,3 +291,13 @@ func udpListenAddr(addr *net.UDPAddr) string {
 	}
 	return addr.String()
 }
+
+func udpListenNetwork(addr *net.UDPAddr) string {
+	if addr == nil || addr.IP == nil {
+		return "udp"
+	}
+	if addr.IP.To4() != nil {
+		return "udp4"
+	}
+	return "udp6"
+}

cmd/internal/transport/kcp_test.go

@@ -204,6 +204,55 @@ func TestKCPCloseIsIdempotent(t *testing.T) {
 	}
 }
 
+func TestResolveUDPListenConfigSelectsSocketFamily(t *testing.T) {
+	tests := []struct {
+		name        string
+		listenAddr  string
+		wantNetwork string
+		wantAddr    string
+	}{
+		{
+			name:        "ipv4 unspecified",
+			listenAddr:  "0.0.0.0:10909",
+			wantNetwork: "udp4",
+			wantAddr:    "0.0.0.0:10909",
+		},
+		{
+			name:        "ipv4 loopback",
+			listenAddr:  "127.0.0.1:10909",
+			wantNetwork: "udp4",
+			wantAddr:    "127.0.0.1:10909",
+		},
+		{
+			name:        "ipv6 loopback",
+			listenAddr:  "[::1]:10909",
+			wantNetwork: "udp6",
+			wantAddr:    "[::1]:10909",
+		},
+		{
+			name:        "host omitted",
+			listenAddr:  ":10909",
+			wantNetwork: "udp",
+			wantAddr:    ":10909",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotNetwork, gotAddr, err := ResolveUDPListenConfig(tt.listenAddr)
+			if err != nil {
+				t.Fatalf("ResolveUDPListenConfig(%q) error = %v", tt.listenAddr, err)
+			}
+			if gotNetwork != tt.wantNetwork {
+				t.Fatalf("network = %q, want %q", gotNetwork, tt.wantNetwork)
+			}
+			if gotAddr.String() != tt.wantAddr {
+				t.Fatalf("addr = %q, want %q", gotAddr.String(), tt.wantAddr)
+			}
+		})
+	}
+}
+
 func newKCPConnPair(t *testing.T, senderOpts []KCPOption, receiverOpts []KCPOption, senderPacketLogger KCPPacketDebugLogger, receiverPacketLogger KCPPacketDebugLogger) (*KCPConn, <-chan kcpAcceptResult, func()) {
 	t.Helper()