mirror of
https://github.com/e1732a364fed/v2ray_simple.git
synced 2025-10-10 03:00:08 +08:00
348 lines
9.1 KiB
Go
348 lines
9.1 KiB
Go
package socks5
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"log"
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"net"
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"net/url"
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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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"github.com/hahahrfool/v2ray_simple/proxy"
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)
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func init() {
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proxy.RegisterServer(Name, &ServerCreator{})
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}
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// TODO: Support Auth
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type Server struct {
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proxy.ProxyCommonStruct
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//user string
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//password string
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}
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type ServerCreator struct{}
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func (_ ServerCreator) NewServerFromURL(u *url.URL) (proxy.Server, error) {
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s := &Server{}
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return s, nil
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}
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func (_ ServerCreator) NewServer(dc *proxy.ListenConf) (proxy.Server, error) {
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s := &Server{}
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return s, nil
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}
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func (s *Server) Name() string { return Name }
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//English: https://www.ietf.org/rfc/rfc1928.txt
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//中文： https://aber.sh/articles/Socks5/
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// 参考 https://studygolang.com/articles/31404
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// 处理tcp收到的请求. 注意, udp associate后的 udp请求并不通过此函数处理, 而是由 UDPConn.StartReadRequest 处理
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func (s *Server) Handshake(underlay net.Conn) (io.ReadWriter, *netLayer.Addr, error) {
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// Set handshake timeout 4 seconds
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if err := underlay.SetReadDeadline(time.Now().Add(time.Second * 4)); err != nil {
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return nil, nil, err
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}
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defer underlay.SetReadDeadline(time.Time{})
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buf := utils.GetPacket()
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defer utils.PutPacket(buf)
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// Read hello message
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// 一般握手包发来的是 [5 1 0]
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n, err := underlay.Read(buf)
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if err != nil || n == 0 {
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return nil, nil, fmt.Errorf("failed to read hello: %w", err)
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}
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version := buf[0]
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if version != Version5 {
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return nil, nil, fmt.Errorf("unsupported socks version %v", version)
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}
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// Write hello response， [5 0]
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// TODO: Support Auth
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_, err = underlay.Write([]byte{Version5, AuthNone})
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if err != nil {
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return nil, nil, fmt.Errorf("failed to write hello response: %w", err)
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}
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// Read command message，
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n, err = underlay.Read(buf)
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if err != nil || n < 7 { // Shortest length is 7
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return nil, nil, fmt.Errorf("read socks5 failed, msgTooShort: %w", err)
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}
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// 一般可以为 5 1 0 3 n，3表示域名，n是域名长度，然后域名很可能是 119 119 119 46 开头，表示 www.
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// 比如百度就是 [5 1 0 3 13 119 119 119 46 98]
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cmd := buf[1]
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if cmd == CmdBind {
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return nil, nil, fmt.Errorf("unsuppoted command %v", cmd)
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}
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l := 2
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off := 4
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var theIP net.IP
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switch buf[3] {
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case ATypIP4:
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l += net.IPv4len
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theIP = make(net.IP, net.IPv4len)
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case ATypIP6:
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l += net.IPv6len
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theIP = make(net.IP, net.IPv6len)
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case ATypDomain:
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l += int(buf[4])
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off = 5
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default:
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return nil, nil, fmt.Errorf("unknown address type %v", buf[3])
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}
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if len(buf[off:]) < l {
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return nil, nil, errors.New("short command request")
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}
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var theName string
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if theIP != nil {
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copy(theIP, buf[off:])
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} else {
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theName = string(buf[off : off+l-2])
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}
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var thePort int
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thePort = int(buf[off+l-2])<<8 | int(buf[off+l-1])
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//根据 socks5标准，“使用UDP ASSOCIATE时，客户端的请求包中(DST.ADDR, DST.PORT)不再是目标的地址，而是客户端指定本身用于发送UDP数据包的地址和端口”
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//然后服务器会传回专门适用于客户端的 一个 服务器的 udp的ip和地址；然后之后客户端再专门 向udp地址发送连接，此tcp连接就已经没用。
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//总之，UDP Associate方法并不是 UDP over TCP，完全不同，而且过程中握手用tcp，传输用udp，使用到了两个连接。
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//不过一般作为NAT内网中的客户端是无法知道自己实际呈现给服务端的udp地址的, 所以没什么太大用
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// 但是, 如果不指定的话，udp associate 就会认为未来一切发往我们新生成的端口的连接都是属于该客户端, 显然有风险
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// 更不用说这样 的 udp associate 会重复使用很多 随机udp端口，特征很明显。
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// 总之 udp associate 只能用于内网环境。
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if cmd == CmdUDPAssociate {
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//这里我们serverAddr直接返回0.0.0.0即可，也实在想不到谁会返回一个另一个ip地址出来。
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//随机生成一个端口专门用于处理该客户端。这是我的想法。
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bindPort := netLayer.RandPort()
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udpPreparedAddr := &net.UDPAddr{
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IP: []byte{0, 0, 0, 0},
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Port: bindPort,
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}
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udpRC, err := net.ListenUDP("udp", udpPreparedAddr)
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if err != nil {
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return nil, nil, errors.New("UDPAssociate: unable to listen udp")
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}
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//ver（5）, rep（0，表示成功）, rsv（0）, atyp(1, 即ipv4), BND.ADDR(4字节的ipv4) , BND.PORT(2字节)
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reply := []byte{Version5, 0x00, 0x00, 0x01, 0, 0, 0, 0, byte(int16(bindPort) >> 8), byte(int16(bindPort) << 8 >> 8)}
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// Write command response
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_, err = underlay.Write(reply)
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if err != nil {
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return nil, nil, fmt.Errorf("failed to write command response: %w", err)
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}
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clientFutureAddr := &netLayer.Addr{
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IP: theIP,
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Name: theName,
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Port: thePort,
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Network: "udp",
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}
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//这里为了解析域名, 就用了 netLayer.Addr 作为中介的方式
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uc := &UDPConn{
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clientSupposedAddr: clientFutureAddr.ToUDPAddr(),
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UDPConn: udpRC,
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}
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return uc, clientFutureAddr, nil
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} else {
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addr := &netLayer.Addr{
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IP: theIP,
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Name: theName,
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Port: thePort,
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}
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// 解读如下：
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//ver（5）, rep（0，表示成功）, rsv（0）, atyp(1, 即ipv4), BND.ADDR （ipv4(0,0,0,0)）, BND.PORT(0, 2字节)
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reply := []byte{Version5, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
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//这个 BND.ADDR和port 按理说不应该传0的，不过如果只作为本地tcp代理的话应该不影响
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_, err = underlay.Write(reply)
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if err != nil {
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return nil, nil, fmt.Errorf("failed to write command response: %w", err)
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}
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return underlay, addr, nil
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}
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}
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type UDPConn struct {
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*net.UDPConn
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clientSupposedAddr *net.UDPAddr //客户端指定的客户端自己未来将使用的公网UDP的Addr
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}
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// 阻塞
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// 从 udpPutter.GetNewUDPResponse 循环阅读 所有需要发送给客户端的 数据，然后通过 u.UDPConn.Write 发送给客户端
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// 这些响应数据是 在其它地方 写入 udpPutter 的, 本 u 是不管 谁、如何 把这个信息 放进去的。
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func (u *UDPConn) StartPushResponse(udpPutter netLayer.UDP_Putter) {
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for {
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raddr, bs, err := udpPutter.GetNewUDPResponse()
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//log.Println("StartPushResponse got new response", raddr, string(bs), err)
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if err != nil {
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break
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}
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buf := &bytes.Buffer{}
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buf.WriteByte(0) //rsv
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buf.WriteByte(0) //rsv
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buf.WriteByte(0) //frag
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var atyp byte = ATypIP4
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if len(raddr.IP) > 4 {
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atyp = ATypIP6
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}
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buf.WriteByte(atyp)
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buf.Write(raddr.IP)
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buf.WriteByte(byte(int16(raddr.Port) >> 8))
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buf.WriteByte(byte(int16(raddr.Port) << 8 >> 8))
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buf.Write(bs)
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//必须要指明raddr
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_, err = u.UDPConn.WriteToUDP(buf.Bytes(), u.clientSupposedAddr)
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if err != nil {
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if utils.CanLogErr() {
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log.Println("socks5, StartPushResponse, write err ", err)
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}
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break
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}
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}
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}
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// 阻塞
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// 监听 与客户端的udp连接 (u.UDPConn)；循环查看客户端发来的请求信息;
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// 然后将该请求 用 udpPutter.WriteUDPRequest 发送给 udpPutter
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// 至于fullcone与否它是不管的。
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// 如果客户端一开始没有指明自己连接本服务端的ip和端口, 则将第一个发来的正确的socks5请求视为该客户端,并记录。
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func (u *UDPConn) StartReadRequest(udpPutter netLayer.UDP_Putter, dialFunc func(targetAddr *netLayer.Addr) (io.ReadWriter, error)) {
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var clientSupposedAddrIsNothing bool
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if len(u.clientSupposedAddr.IP) < 3 || u.clientSupposedAddr.IP.IsUnspecified() {
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clientSupposedAddrIsNothing = true
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}
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bs := make([]byte, netLayer.MaxUDP_packetLen)
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for {
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n, addr, err := u.UDPConn.ReadFromUDP(bs)
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if err != nil {
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if utils.CanLogWarn() {
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log.Println("UDPConn read err", err)
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}
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continue
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}
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if n < 6 {
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if utils.CanLogWarn() {
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log.Println("UDPConn short read err", n)
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}
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continue
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}
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if !clientSupposedAddrIsNothing {
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if !addr.IP.Equal(u.clientSupposedAddr.IP) || addr.Port != u.clientSupposedAddr.Port {
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//just random attack message.
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continue
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}
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}
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atyp := bs[3]
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l := 2 //supposed Minimum Remain Data Lenth
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off := 4 //offset from which the addr data really starts
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var theIP net.IP
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switch atyp {
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case ATypIP4:
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l += net.IPv4len
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theIP = make(net.IP, net.IPv4len)
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case ATypIP6:
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l += net.IPv6len
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theIP = make(net.IP, net.IPv6len)
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case ATypDomain:
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l += int(bs[4])
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off = 5
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default:
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if utils.CanLogWarn() {
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log.Println("UDPConn unknown address type ", atyp)
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}
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continue
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}
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if len(bs[off:]) < l {
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if utils.CanLogWarn() {
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log.Println("UDPConn short command request ", atyp)
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}
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continue
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}
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var theName string
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if theIP != nil {
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copy(theIP, bs[off:])
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} else {
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theName = string(bs[off : off+l-2])
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}
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var thePort int
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thePort = int(bs[off+l-2])<<8 | int(bs[off+l-1])
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newStart := off + l
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//为了解析域名, 我们用 netLayer.Addr 作为中介.
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requestAddr := &netLayer.Addr{
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IP: theIP,
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Name: theName,
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Port: thePort,
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Network: "udp",
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}
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if clientSupposedAddrIsNothing {
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clientSupposedAddrIsNothing = false
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u.clientSupposedAddr = addr
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}
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//log.Println("socks5 server,StartReadRequest, got msg", thisaddr, string(bs[newStart:n]))
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udpPutter.WriteUDPRequest(requestAddr.ToUDPAddr(), bs[newStart:n], dialFunc)
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}
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}
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