forked from armon/go-socks5
/
auth.go
145 lines (117 loc) · 3.27 KB
/
auth.go
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package socks5
import (
"fmt"
"io"
)
const (
noAuth = uint8(0)
noAcceptable = uint8(255)
userPassAuth = uint8(2)
userAuthVersion = uint8(1)
authSuccess = uint8(0)
authFailure = uint8(1)
)
var (
UserAuthFailed = fmt.Errorf("User authentication failed")
NoSupportedAuth = fmt.Errorf("No supported authentication mechanism")
)
type Authenticator interface {
Authenticate(reader io.Reader, writer io.Writer) error
GetCode() uint8
}
// NoAuthAuthenticator is used to handle the "No Authentication" mode
type NoAuthAuthenticator struct {}
func (a NoAuthAuthenticator) GetCode() uint8 {
return noAuth
}
func (a NoAuthAuthenticator) Authenticate(reader io.Reader, writer io.Writer) error {
_, err := writer.Write([]byte{socks5Version, noAuth})
return err
}
// UserPassAuthenticator is used to handle username/password based
// authentication
type UserPassAuthenticator struct {
Credentials CredentialStore
}
func (a UserPassAuthenticator) GetCode() uint8 {
return userPassAuth
}
func (a UserPassAuthenticator) Authenticate(reader io.Reader, writer io.Writer) error {
// Tell the client to use user/pass auth
if _, err := writer.Write([]byte{socks5Version, userPassAuth}); err != nil {
return err
}
// Get the version and username length
header := []byte{0, 0}
if _, err := io.ReadAtLeast(reader, header, 2); err != nil {
return err
}
// Ensure we are compatible
if header[0] != userAuthVersion {
return fmt.Errorf("Unsupported auth version: %v", header[0])
}
// Get the user name
userLen := int(header[1])
user := make([]byte, userLen)
if _, err := io.ReadAtLeast(reader, user, userLen); err != nil {
return err
}
// Get the password length
if _, err := reader.Read(header[:1]); err != nil {
return err
}
// Get the password
passLen := int(header[0])
pass := make([]byte, passLen)
if _, err := io.ReadAtLeast(reader, pass, passLen); err != nil {
return err
}
// Verify the password
if a.Credentials.Valid(string(user), string(pass)) {
if _, err := writer.Write([]byte{userAuthVersion, authSuccess}); err != nil {
return err
}
} else {
if _, err := writer.Write([]byte{userAuthVersion, authFailure}); err != nil {
return err
}
return UserAuthFailed
}
// Done
return nil
}
// authenticate is used to handle connection authentication
func (s *Server) authenticate(conn io.Writer, bufConn io.Reader) error {
// Get the methods
methods, err := readMethods(bufConn)
if err != nil {
return fmt.Errorf("Failed to get auth methods: %v", err)
}
// Select a usable method
for _, method := range methods {
cator, found := s.authMethods[method]
if found {
return cator.Authenticate(bufConn, conn)
}
}
// No usable method found
return noAcceptableAuth(conn)
}
// noAcceptableAuth is used to handle when we have no eligible
// authentication mechanism
func noAcceptableAuth(conn io.Writer) error {
conn.Write([]byte{socks5Version, noAcceptable})
return NoSupportedAuth
}
// readMethods is used to read the number of methods
// and proceeding auth methods
func readMethods(r io.Reader) ([]byte, error) {
header := []byte{0}
if _, err := r.Read(header); err != nil {
return nil, err
}
numMethods := int(header[0])
methods := make([]byte, numMethods)
_, err := io.ReadAtLeast(r, methods, numMethods)
return methods, err
}