78 lines
2.0 KiB
Go
78 lines
2.0 KiB
Go
package socks
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import (
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"fmt"
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"io"
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)
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const (
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// NoAuth means no authentication is used when connecting
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NoAuth = uint8(0)
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// UserPassAuth means a user/password is used when connecting
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UserPassAuth = uint8(2)
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noAcceptable = uint8(255)
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userAuthVersion = uint8(1)
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authSuccess = uint8(0)
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authFailure = uint8(1)
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)
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// AuthHandler handles socks authenication requests
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type AuthHandler interface {
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Handle(io.Reader, io.Writer) error
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Register(uint8, Authenticator)
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}
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// StandardAuthHandler loads the default authenticators
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type StandardAuthHandler struct {
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authenticators map[uint8]Authenticator
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}
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// NewAuthHandler creates a default auth handler
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func NewAuthHandler() AuthHandler {
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defaults := make(map[uint8]Authenticator)
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defaults[NoAuth] = NewNoAuthAuthenticator()
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return &StandardAuthHandler{
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authenticators: defaults,
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}
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}
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// Register adds/replaces an Authenticator to use when handling Authentication requests
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func (h *StandardAuthHandler) Register(method uint8, a Authenticator) {
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h.authenticators[method] = a
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}
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// Handle gets the methods from the SOCKS5 client and authenicates with the first supported method
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func (h *StandardAuthHandler) Handle(bufConn io.Reader, conn io.Writer) error {
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methods, err := readMethods(bufConn)
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if err != nil {
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return fmt.Errorf("Failed to read auth methods: %v", err)
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}
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// first supported method is used
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for _, method := range methods {
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authenticator := h.authenticators[method]
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if authenticator != nil {
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return authenticator.Handle(bufConn, conn)
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}
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}
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// failed to authenticate. No supported authentication type found
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conn.Write([]byte{socks5Version, noAcceptable})
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return fmt.Errorf("unknown authentication type")
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}
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// readMethods is used to read the number and type of methods
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func readMethods(r io.Reader) ([]byte, error) {
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header := []byte{0}
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if _, err := r.Read(header); err != nil {
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return nil, err
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}
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numMethods := int(header[0])
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methods := make([]byte, numMethods)
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_, err := io.ReadAtLeast(r, methods, numMethods)
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return methods, err
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}
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