97 lines
2.7 KiB
Go
97 lines
2.7 KiB
Go
package socks
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import (
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"errors"
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"net"
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)
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func (sesh *session) dialSocks5(targetAddr string) (_ net.Conn, err error) {
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conn, err := sesh.internalDial()
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if err != nil {
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return nil, err
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}
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var req = newRequestBuilder()
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version := byte(5) // socks version 5
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method := byte(0) // method 0: no authentication (only anonymous access supported for now)
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if sesh.Auth != nil {
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method = 2 // method 2: username/password
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}
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// version identifier/method selection request
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req.MustWriteByte(version)
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req.MustWriteByte(1) // number of methods
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req.MustWriteByte(method)
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resp, err := sesh.sendReceive(conn, req.Bytes())
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if err != nil {
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return nil, err
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} else if len(resp) != 2 {
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return nil, errors.New("server does not respond properly")
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} else if resp[0] != 5 {
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return nil, errors.New("server does not support Socks 5")
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} else if resp[1] != method {
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return nil, errors.New("socks method negotiation failed")
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}
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if sesh.Auth != nil {
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req.MustReset()
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version = byte(1) // user/password version (1)
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req.MustWriteByte(version)
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req.MustWriteByte(byte(len(sesh.Auth.Username))) // username length
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req.MustWrite([]byte(sesh.Auth.Username)) // username
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req.MustWriteByte(byte(len(sesh.Auth.Password))) // password length
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req.MustWrite([]byte(sesh.Auth.Password)) // password
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resp, err = sesh.sendReceive(conn, req.Bytes())
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switch {
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case err != nil:
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return nil, err
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case len(resp) != 2:
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return nil, errors.New("server does not respond properly")
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case resp[0] != version:
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return nil, errors.New("server does not support SOCKS5")
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case resp[1] != 0:
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return nil, errors.New("socks authentication failed")
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default:
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// fmt.Println("socks authentication succeeded")
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// authentication succeeded
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}
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}
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// detail request
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host, port, err := splitHostPort(targetAddr)
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if err != nil {
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return nil, err
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}
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req.MustReset()
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req.MustWriteByte(5) // socks version 5
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req.MustWriteByte(1) // command 1 (CONNECT)
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req.MustWriteByte(0) // reserved
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req.MustWriteByte(3) // address type 3 (domain name)
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req.MustWriteByte(byte(len(host))) // length of domain name
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req.MustWrite([]byte(host)) // domain name
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req.MustWriteByte(byte(port >> 8)) // higher byte of destination port
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req.MustWriteByte(byte(port)) // lower byte of destination port (big endian)
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resp, err = sesh.sendReceive(conn, req.Bytes())
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defer func() {
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bufs.MustPut(req.Buffer)
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req.Buffer = nil
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}()
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switch {
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case err != nil:
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return
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case len(resp) != 10:
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return nil, errors.New("server does not respond properly")
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case resp[1] != 0:
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return nil, errors.New("can't complete SOCKS5 connection")
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default:
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// no-op
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}
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return conn, nil
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}
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