init

nat.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"net"
+	"time"
+)
+
+func natTest(serverHost string, serverPort int, localPort int) (publicIP string, isPublicIP int, publicPort int, err error) {
+	conn, err := net.ListenPacket("udp", fmt.Sprintf(":%d", localPort))
+	if err != nil {
+		return "", 0, 0, err
+	}
+	defer conn.Close()
+
+	dst, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", serverHost, serverPort))
+	if err != nil {
+		return "", 0, 0, err
+	}
+
+	// The connection can write data to the desired address.
+	msg, err := newMessage(MsgNATDetect, 0, &NatDetectReq{SrcPort: localPort, EchoPort: EchoPort})
+	_, err = conn.WriteTo(msg, dst)
+	if err != nil {
+		return "", 0, 0, err
+	}
+	deadline := time.Now().Add(NatTestTimeout)
+	err = conn.SetReadDeadline(deadline)
+	if err != nil {
+		return "", 0, 0, err
+	}
+	buffer := make([]byte, 1024)
+	nRead, _, err := conn.ReadFrom(buffer)
+	if err != nil {
+		gLog.Println(LevelERROR, "NAT detect error:", err)
+		return "", 0, 0, err
+	}
+	natRsp := NatDetectRsp{}
+	err = json.Unmarshal(buffer[openP2PHeaderSize:nRead], &natRsp)
+	return natRsp.IP, natRsp.IsPublicIP, natRsp.Port, nil
+}
+
+func getNATType(host string, udp1 int, udp2 int) (publicIP string, NATType int, err error) {
+	// the random local port may be used by other.
+	go echo()
+	localPort := int(rand.Uint32()%10000 + 50000)
+	ip1, isPublicIP, port1, err := natTest(host, udp1, localPort)
+	gLog.Printf(LevelDEBUG, "local port:%d  nat port:%d", localPort, port1)
+	if err != nil {
+		return "", 0, err
+	}
+	if isPublicIP == 1 {
+		return ip1, NATNone, nil
+	}
+	ip2, _, port2, err := natTest(host, udp2, localPort)
+	gLog.Printf(LevelDEBUG, "local port:%d  nat port:%d", localPort, port2)
+	if err != nil {
+		return "", 0, err
+	}
+	if ip1 != ip2 {
+		return "", 0, fmt.Errorf("ip have changed, please retry again")
+	}
+	natType := NATSymmetric
+	if port1 == port2 {
+		natType = NATCone
+	}
+	//TODO: NATNone
+	return ip1, natType, nil
+}
+
+const (
+	UDPPort1 = 27182
+	UDPPort2 = 27183
+	EchoPort = 31415
+)
+
+func echo() {
+	conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: EchoPort})
+	if err != nil {
+		gLog.Println(LevelERROR, "echo server listen error:", err)
+		return
+	}
+	buf := make([]byte, 1600)
+	defer conn.Close()
+	// wait 5s for echo testing
+	conn.SetReadDeadline(time.Now().Add(time.Second * 5))
+	n, addr, err := conn.ReadFromUDP(buf)
+	if err != nil {
+		return
+	}
+	conn.WriteToUDP(buf[0:n], addr)
+}