70 lines
2.0 KiB
Go
70 lines
2.0 KiB
Go
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package socks5
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import (
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"errors"
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"fmt"
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"io"
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)
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var (
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ErrSubnegotiationVersionNotSupported = errors.New("subnegotiation version not supported")
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ErrUsernameNotValid = errors.New("username not valid")
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ErrPasswordNotValid = errors.New("password not valid")
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)
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// See https://datatracker.ietf.org/doc/html/rfc1929#section-2
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func usernamePasswordSubnegotiate(conn io.ReadWriter, username, password string) (err error) {
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status := byte(1)
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const defaultVersion = byte(1)
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const headerLength = 2
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var header [headerLength]byte
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_, err = io.ReadFull(conn, header[:])
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if err != nil {
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_, _ = conn.Write([]byte{defaultVersion, status})
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return fmt.Errorf("reading header: %w", err)
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}
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if header[0] != authUsernamePasswordSubNegotiation1 {
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_, _ = conn.Write([]byte{defaultVersion, status})
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return fmt.Errorf("%w: %d", ErrSubnegotiationVersionNotSupported, header[0])
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}
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version := header[0]
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usernameBytes := make([]byte, header[1])
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_, err = io.ReadFull(conn, usernameBytes)
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if err != nil {
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_, _ = conn.Write([]byte{version, status})
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return fmt.Errorf("reading username bytes: %w", err)
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} else if username != string(usernameBytes) {
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_, _ = conn.Write([]byte{version, status})
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return fmt.Errorf("%w: %s", ErrUsernameNotValid, string(usernameBytes))
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}
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const passwordHeaderLength = 1
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passwordHeader := make([]byte, passwordHeaderLength)
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_, err = io.ReadFull(conn, passwordHeader[:])
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if err != nil {
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_, _ = conn.Write([]byte{version, status})
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return fmt.Errorf("reading password length: %w", err)
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}
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passwordBytes := make([]byte, passwordHeader[0])
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_, err = io.ReadFull(conn, passwordBytes)
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if err != nil {
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_, _ = conn.Write([]byte{version, status})
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return fmt.Errorf("reading password bytes: %w", err)
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} else if password != string(passwordBytes) {
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_, _ = conn.Write([]byte{version, status})
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return fmt.Errorf("%w: %s", ErrPasswordNotValid, string(passwordBytes))
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}
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status = 0
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_, err = conn.Write([]byte{version, status})
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if err != nil {
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return fmt.Errorf("writing success status: %w", err)
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}
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return nil
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}
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