mirror of
https://github.com/net-byte/vtun
synced 2024-03-14 10:50:03 +08:00
113 lines
2.8 KiB
Go
113 lines
2.8 KiB
Go
package server
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import (
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"fmt"
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"log"
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"net"
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"time"
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"github.com/net-byte/vtun/common/cipher"
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"github.com/net-byte/vtun/common/config"
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"github.com/net-byte/vtun/tun"
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"github.com/patrickmn/go-cache"
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"github.com/songgao/water"
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"github.com/songgao/water/waterutil"
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)
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// StartUDPServer start udp server
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func StartUDPServer(config config.Config) {
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config.Init()
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iface := tun.CreateTun(config.CIDR)
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localAddr, err := net.ResolveUDPAddr("udp", config.LocalAddr)
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if err != nil {
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log.Fatalln("failed to get UDP socket:", err)
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}
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conn, err := net.ListenUDP("udp", localAddr)
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if err != nil {
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log.Fatalln("failed to listen on UDP socket:", err)
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}
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defer conn.Close()
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log.Printf("vtun udp server started on %v,CIDR is %v", config.LocalAddr, config.CIDR)
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// forward data to client
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forwarder := &Forwarder{localConn: conn, connCache: cache.New(30*time.Minute, 10*time.Minute)}
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go forwarder.forward(iface, conn)
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// read data from client
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buf := make([]byte, 1500)
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for {
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n, cliAddr, err := conn.ReadFromUDP(buf)
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if err != nil || n == 0 {
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continue
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}
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// decrypt data
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b := cipher.Decrypt(buf[:n])
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if !waterutil.IsIPv4(b) {
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continue
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}
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iface.Write(b)
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srcAddr := srcAddr(b)
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dstAddr := dstAddr(b)
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if srcAddr == "" || dstAddr == "" {
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continue
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}
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key := fmt.Sprintf("%v->%v", srcAddr, dstAddr)
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forwarder.connCache.Set(key, cliAddr, cache.DefaultExpiration)
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}
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}
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type Forwarder struct {
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localConn *net.UDPConn
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connCache *cache.Cache
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}
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func (f *Forwarder) forward(iface *water.Interface, conn *net.UDPConn) {
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packet := make([]byte, 1500)
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for {
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n, err := iface.Read(packet)
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if err != nil || n == 0 {
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continue
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}
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b := packet[:n]
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if !waterutil.IsIPv4(b) {
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continue
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}
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dstAddr := dstAddr(b)
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srcAddr := srcAddr(b)
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if dstAddr == "" || srcAddr == "" {
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continue
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}
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key := fmt.Sprintf("%v->%v", dstAddr, srcAddr)
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v, ok := f.connCache.Get(key)
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if ok {
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// encrypt data
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b = cipher.Encrypt(b)
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f.localConn.WriteToUDP(b, v.(*net.UDPAddr))
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}
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}
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}
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func srcAddr(b []byte) string {
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if waterutil.IPv4Protocol(b) == waterutil.UDP || waterutil.IPv4Protocol(b) == waterutil.TCP {
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ip := waterutil.IPv4Source(b)
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port := waterutil.IPv4SourcePort(b)
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addr := fmt.Sprintf("%s:%d", ip.To4().String(), port)
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return addr
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} else if waterutil.IPv4Protocol(b) == waterutil.ICMP {
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ip := waterutil.IPv4Source(b)
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return ip.To4().String()
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}
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return ""
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}
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func dstAddr(b []byte) string {
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if waterutil.IPv4Protocol(b) == waterutil.UDP || waterutil.IPv4Protocol(b) == waterutil.TCP {
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ip := waterutil.IPv4Destination(b)
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port := waterutil.IPv4DestinationPort(b)
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addr := fmt.Sprintf("%s:%d", ip.To4().String(), port)
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return addr
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} else if waterutil.IPv4Protocol(b) == waterutil.ICMP {
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ip := waterutil.IPv4Destination(b)
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return ip.To4().String()
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}
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return ""
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}
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