mirror of
https://github.com/e1732a364fed/v2ray_simple.git
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144 lines
3.1 KiB
Go
144 lines
3.1 KiB
Go
/*
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Package tproxy implements tproxy.
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透明代理只能用于linux。
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About TProxy 关于透明代理
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透明代理原理
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https://www.kernel.org/doc/html/latest/networking/tproxy.html
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golang 示例
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https://github.com/LiamHaworth/go-tproxy/blob/master/tproxy_tcp.go
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c 语言 示例
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https://github.com/FarFetchd/simple_tproxy_example/blob/master/tproxy_captive_portal.c
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关键点在于
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1. 要使用 syscall.IP_TRANSPARENT 监听
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2. 监听到的 连接 的 localAddr实际上是 真实的目标地址, 而不是我们监听的地址;
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我们在本包里要做的事情就是 模仿 上面的 golang示例,
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但是，上面的go示例有一个特点, 它是直接利用客户端自己的地址+reuse端口的方法去拨号实际地址的,而我们不需要那样做。
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而且, udp 的过程更加特殊。
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总之，这种情况完全不适配 proxy.Server 的接口, 应该单独拿出来, 属于网络层的特殊情况.
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另外就是，偶然发现，trojan-go也是使用的 上面的示例的代码。
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同时，trojan-go还使用了
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https://github.com/cybozu-go/transocks/blob/master/original_dst_linux.go
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*/
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package tproxy
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import (
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"io"
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"net"
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"os"
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"time"
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"github.com/hahahrfool/v2ray_simple/netLayer"
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"github.com/hahahrfool/v2ray_simple/utils"
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)
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func HandshakeTCP(tcpConn *net.TCPConn) netLayer.Addr {
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targetTCPAddr := tcpConn.LocalAddr().(*net.TCPAddr)
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return netLayer.Addr{
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IP: targetTCPAddr.IP,
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Port: targetTCPAddr.Port,
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}
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}
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var udpMsgConnMap = make(map[netLayer.HashableAddr]*MsgConn)
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func HandshakeUDP(underlay *net.UDPConn) (netLayer.MsgConn, netLayer.Addr, error) {
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bs := utils.GetPacket()
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n, src, dst, err := ReadFromUDP(underlay, bs)
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if err != nil {
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return nil, netLayer.Addr{}, err
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}
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ad := netLayer.NewAddrFromUDPAddr(src)
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hash := ad.GetHashable()
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conn, found := udpMsgConnMap[hash]
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if !found {
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conn = &MsgConn{
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ourSrcAddr: src,
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readChan: make(chan netLayer.AddrData, 5),
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closeChan: make(chan struct{}),
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}
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udpMsgConnMap[hash] = conn
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}
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conn.readChan <- netLayer.AddrData{Data: bs[:n], Addr: netLayer.NewAddrFromUDPAddr(dst)}
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return conn, netLayer.NewAddrFromUDPAddr(dst), nil
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}
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//implements netLayer.MsgConn
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type MsgConn struct {
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ourSrcAddr *net.UDPAddr
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readChan chan netLayer.AddrData
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closeChan chan struct{}
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}
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func (mc *MsgConn) Close() error {
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return nil
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}
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func (mc *MsgConn) CloseConnWithRaddr(raddr netLayer.Addr) error {
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return nil
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}
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func (mc *MsgConn) Fullcone() bool {
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return true
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}
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func (mc *MsgConn) ReadMsgFrom() ([]byte, netLayer.Addr, error) {
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timeoutChan := time.After(netLayer.UDP_timeout)
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select {
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case <-mc.closeChan:
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return nil, netLayer.Addr{}, io.EOF
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case <-timeoutChan:
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return nil, netLayer.Addr{}, os.ErrDeadlineExceeded
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case newmsg := <-mc.readChan:
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return newmsg.Data, newmsg.Addr, nil
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}
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}
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// 通过透明代理 写回 客户端
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func (mc *MsgConn) WriteMsgTo(p []byte, addr netLayer.Addr) error {
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back, err := DialUDP(
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"udp",
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&net.UDPAddr{
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IP: addr.IP,
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Port: addr.Port,
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},
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mc.ourSrcAddr,
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)
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if err != nil {
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return err
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}
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_, err = back.Write(p)
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if err != nil {
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return err
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}
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back.Close()
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return nil
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}
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