AUTH-2394 added socks5 proxy

socks/auth_handler.go

@@ -0,0 +1,77 @@
+package socks
+
+import (
+	"fmt"
+	"io"
+)
+
+const (
+	// NoAuth means no authentication is used when connecting
+	NoAuth = uint8(0)
+
+	// UserPassAuth means a user/password is used when connecting
+	UserPassAuth = uint8(2)
+
+	noAcceptable    = uint8(255)
+	userAuthVersion = uint8(1)
+	authSuccess     = uint8(0)
+	authFailure     = uint8(1)
+)
+
+// AuthHandler handles socks authenication requests
+type AuthHandler interface {
+	Handle(io.Reader, io.Writer) error
+	Register(uint8, Authenticator)
+}
+
+// StandardAuthHandler loads the default authenticators
+type StandardAuthHandler struct {
+	authenticators map[uint8]Authenticator
+}
+
+// NewAuthHandler creates a default auth handler
+func NewAuthHandler() AuthHandler {
+	defaults := make(map[uint8]Authenticator)
+	defaults[NoAuth] = NewNoAuthAuthenticator()
+	return &StandardAuthHandler{
+		authenticators: defaults,
+	}
+}
+
+// Register adds/replaces an Authenticator to use when handling Authentication requests
+func (h *StandardAuthHandler) Register(method uint8, a Authenticator) {
+	h.authenticators[method] = a
+}
+
+// Handle gets the methods from the SOCKS5 client and authenicates with the first supported method
+func (h *StandardAuthHandler) Handle(bufConn io.Reader, conn io.Writer) error {
+	methods, err := readMethods(bufConn)
+	if err != nil {
+		return fmt.Errorf("Failed to read auth methods: %v", err)
+	}
+
+	// first supported method is used
+	for _, method := range methods {
+		authenticator := h.authenticators[method]
+		if authenticator != nil {
+			return authenticator.Handle(bufConn, conn)
+		}
+	}
+
+	// failed to authenticate. No supported authentication type found
+	conn.Write([]byte{socks5Version, noAcceptable})
+	return fmt.Errorf("unknown authentication type")
+}
+
+// readMethods is used to read the number and type of 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
+}