Introduce AuthContext struct and refactor auth api using it

auth.go

@@ -6,9 +6,9 @@ import (
 )
 
 const (
-	noAuth          = uint8(0)
+	NoAuth          = uint8(0)
 	noAcceptable    = uint8(255)
-	userPassAuth    = uint8(2)
+	UserPassAuth    = uint8(2)
 	userAuthVersion = uint8(1)
 	authSuccess     = uint8(0)
 	authFailure     = uint8(1)
@@ -19,21 +19,32 @@ var (
 	NoSupportedAuth = fmt.Errorf("No supported authentication mechanism")
 )
 
+// A Request encapsulates authentication state provided
+// during negotiation
+type AuthContext struct {
+	// Provided auth method
+	Method uint8
+	// Payload provided during negotiation.
+	// Keys depend on the used auth method.
+	// For UserPassauth contains Username
+	Payload map[string]string
+}
+
 type Authenticator interface {
-	Authenticate(reader io.Reader, writer io.Writer) error
+	Authenticate(reader io.Reader, writer io.Writer) (*AuthContext, error)
 	GetCode() uint8
 }
 
 // NoAuthAuthenticator is used to handle the "No Authentication" mode
-type NoAuthAuthenticator struct {}
+type NoAuthAuthenticator struct{}
 
 func (a NoAuthAuthenticator) GetCode() uint8 {
-	return noAuth
+	return NoAuth
 }
 
-func (a NoAuthAuthenticator) Authenticate(reader io.Reader, writer io.Writer) error {
+func (a NoAuthAuthenticator) Authenticate(reader io.Reader, writer io.Writer) (*AuthContext, error) {
-	_, err := writer.Write([]byte{socks5Version, noAuth})
+	_, err := writer.Write([]byte{socks5Version, NoAuth})
-	return err
+	return &AuthContext{NoAuth, nil}, err
 }
 
 // UserPassAuthenticator is used to handle username/password based
@@ -43,70 +54,67 @@ type UserPassAuthenticator struct {
 }
 
 func (a UserPassAuthenticator) GetCode() uint8 {
-	return userPassAuth
+	return UserPassAuth
 }
 
-func (a UserPassAuthenticator) Authenticate(reader io.Reader, writer io.Writer) error {
+func (a UserPassAuthenticator) Authenticate(reader io.Reader, writer io.Writer) (*AuthContext, error) {
 	// Tell the client to use user/pass auth
-	if _, err := writer.Write([]byte{socks5Version, userPassAuth}); err != nil {
+	if _, err := writer.Write([]byte{socks5Version, UserPassAuth}); err != nil {
-		return err
+		return nil, err
 	}
 
 	// Get the version and username length
 	header := []byte{0, 0}
 	if _, err := io.ReadAtLeast(reader, header, 2); err != nil {
-		return err
+		return nil, err
 	}
 
 	// Ensure we are compatible
 	if header[0] != userAuthVersion {
-		return fmt.Errorf("Unsupported auth version: %v", header[0])
+		return nil, 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
+		return nil, err
 	}
 
 	// Get the password length
 	if _, err := reader.Read(header[:1]); err != nil {
-		return err
+		return nil, err
 	}
 
 	// Get the password
 	passLen := int(header[0])
 	pass := make([]byte, passLen)
 	if _, err := io.ReadAtLeast(reader, pass, passLen); err != nil {
-		return err
+		return nil, err
 	}
 
 	// Verify the password
 	if a.Credentials.Valid(string(user), string(pass)) {
 		if _, err := writer.Write([]byte{userAuthVersion, authSuccess}); err != nil {
-			return err
+			return nil, err
 		}
 	} else {
 		if _, err := writer.Write([]byte{userAuthVersion, authFailure}); err != nil {
-			return err
+			return nil, err
 		}
-		return UserAuthFailed
+		return nil, UserAuthFailed
 	}
 
 	// Done
-	return nil
+	return &AuthContext{UserPassAuth, map[string]string{"Username": string(user)}}, nil
-
 }
 
-
-
 // authenticate is used to handle connection authentication
-func (s *Server) authenticate(conn io.Writer, bufConn io.Reader) error {
+func (s *Server) authenticate(conn io.Writer, bufConn io.Reader) (*AuthContext, error) {
 	// Get the methods
 	methods, err := readMethods(bufConn)
 	if err != nil {
-		return fmt.Errorf("Failed to get auth methods: %v", err)
+		return nil, fmt.Errorf("Failed to get auth methods: %v", err)
 	}
 
 	// Select a usable method
@@ -118,11 +126,9 @@ func (s *Server) authenticate(conn io.Writer, bufConn io.Reader) error {
 	}
 
 	// No usable method found
-	return noAcceptableAuth(conn)
+	return nil, noAcceptableAuth(conn)
 }
 
-
-
 // noAcceptableAuth is used to handle when we have no eligible
 // authentication mechanism
 func noAcceptableAuth(conn io.Writer) error {

auth_test.go

@@ -7,47 +7,66 @@ import (
 
 func TestNoAuth(t *testing.T) {
 	req := bytes.NewBuffer(nil)
-	req.Write([]byte{1, noAuth})
+	req.Write([]byte{1, NoAuth})
 	var resp bytes.Buffer
 
 	s, _ := New(&Config{})
-	if err := s.authenticate(&resp, req); err != nil {
+	ctx, err := s.authenticate(&resp, req)
+	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
 
+	if ctx.Method != NoAuth {
+		t.Fatal("Invalid Context Method")
+	}
+
 	out := resp.Bytes()
-	if !bytes.Equal(out, []byte{socks5Version, noAuth}) {
+	if !bytes.Equal(out, []byte{socks5Version, NoAuth}) {
 		t.Fatalf("bad: %v", out)
 	}
 }
 
 func TestPasswordAuth_Valid(t *testing.T) {
 	req := bytes.NewBuffer(nil)
-	req.Write([]byte{2, noAuth, userPassAuth})
+	req.Write([]byte{2, NoAuth, UserPassAuth})
 	req.Write([]byte{1, 3, 'f', 'o', 'o', 3, 'b', 'a', 'r'})
 	var resp bytes.Buffer
 
 	cred := StaticCredentials{
 		"foo": "bar",
 	}
-	
+
 	cator := UserPassAuthenticator{Credentials: cred}
 
-	s, _ := New(&Config{AuthMethods:[]Authenticator{cator}})
+	s, _ := New(&Config{AuthMethods: []Authenticator{cator}})
 
-	if err := s.authenticate(&resp, req); err != nil {
+	ctx, err := s.authenticate(&resp, req)
+	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
 
+	if ctx.Method != UserPassAuth {
+		t.Fatal("Invalid Context Method")
+	}
+
+	val, ok := ctx.Payload["Username"]
+	if !ok {
+		t.Fatal("Missing key Username in auth context's payload")
+	}
+
+	if val != "foo" {
+		t.Fatal("Invalid Username in auth context's payload")
+	}
+
 	out := resp.Bytes()
-	if !bytes.Equal(out, []byte{socks5Version, userPassAuth, 1, authSuccess}) {
+	if !bytes.Equal(out, []byte{socks5Version, UserPassAuth, 1, authSuccess}) {
 		t.Fatalf("bad: %v", out)
 	}
 }
 
 func TestPasswordAuth_Invalid(t *testing.T) {
 	req := bytes.NewBuffer(nil)
-	req.Write([]byte{2, noAuth, userPassAuth})
+	req.Write([]byte{2, NoAuth, UserPassAuth})
 	req.Write([]byte{1, 3, 'f', 'o', 'o', 3, 'b', 'a', 'z'})
 	var resp bytes.Buffer
 
@@ -55,20 +74,26 @@ func TestPasswordAuth_Invalid(t *testing.T) {
 		"foo": "bar",
 	}
 	cator := UserPassAuthenticator{Credentials: cred}
-	s, _ := New(&Config{AuthMethods:[]Authenticator{cator}})
+	s, _ := New(&Config{AuthMethods: []Authenticator{cator}})
-	if err := s.authenticate(&resp, req); err != UserAuthFailed {
+
+	ctx, err := s.authenticate(&resp, req)
+	if err != UserAuthFailed {
 		t.Fatalf("err: %v", err)
 	}
 
+	if ctx != nil {
+		t.Fatal("Invalid Context Method")
+	}
+
 	out := resp.Bytes()
-	if !bytes.Equal(out, []byte{socks5Version, userPassAuth, 1, authFailure}) {
+	if !bytes.Equal(out, []byte{socks5Version, UserPassAuth, 1, authFailure}) {
 		t.Fatalf("bad: %v", out)
 	}
 }
 
 func TestNoSupportedAuth(t *testing.T) {
 	req := bytes.NewBuffer(nil)
-	req.Write([]byte{1, noAuth})
+	req.Write([]byte{1, NoAuth})
 	var resp bytes.Buffer
 
 	cred := StaticCredentials{
@@ -76,11 +101,17 @@ func TestNoSupportedAuth(t *testing.T) {
 	}
 	cator := UserPassAuthenticator{Credentials: cred}
 
-	s, _ := New(&Config{AuthMethods:[]Authenticator{cator}})
+	s, _ := New(&Config{AuthMethods: []Authenticator{cator}})
-	if err := s.authenticate(&resp, req); err != NoSupportedAuth {
+
+	ctx, err := s.authenticate(&resp, req)
+	if err != NoSupportedAuth {
 		t.Fatalf("err: %v", err)
 	}
 
+	if ctx != nil {
+		t.Fatal("Invalid Context Method")
+	}
+
 	out := resp.Bytes()
 	if !bytes.Equal(out, []byte{socks5Version, noAcceptable}) {
 		t.Fatalf("bad: %v", out)