Unify error checking by introducing error codes

common/errors/errors.go

@@ -4,55 +4,86 @@ import (
 	"fmt"
 )
 
+func HasCode(err error, code int) bool {
+	if errWithCode, ok := err.(ErrorWithCode); ok {
+		return errWithCode.Code() == code
+	}
+	return false
+}
+
+type ErrorWithCode interface {
+	error
+	Code() int
+}
+
+type ErrorCode int
+
+func (code ErrorCode) Code() int {
+	return int(code)
+}
+
+func (code ErrorCode) Prefix() string {
+	return fmt.Sprintf("[Error 0x%04X] ", code.Code())
+}
+
 type AuthenticationError struct {
+	ErrorCode
 	AuthDetail interface{}
 }
 
 func NewAuthenticationError(detail interface{}) AuthenticationError {
 	return AuthenticationError{
+		ErrorCode:  1,
 		AuthDetail: detail,
 	}
 }
 
 func (err AuthenticationError) Error() string {
-	return fmt.Sprintf("[Error 0x0001] Invalid auth %v", err.AuthDetail)
+	return fmt.Sprintf("%sInvalid auth %v", err.Prefix(), err.AuthDetail)
 }
 
 type ProtocolVersionError struct {
+	ErrorCode
 	Version int
 }
 
 func NewProtocolVersionError(version int) ProtocolVersionError {
 	return ProtocolVersionError{
-		Version: version,
+		ErrorCode: 2,
+		Version:   version,
 	}
 }
 
 func (err ProtocolVersionError) Error() string {
-	return fmt.Sprintf("[Error 0x0002] Invalid version %d", err.Version)
+	return fmt.Sprintf("%sInvalid version %d", err.Prefix(), err.Version)
 }
 
 type CorruptedPacketError struct {
+	ErrorCode
 }
 
+var corruptedPacketErrorInstance = CorruptedPacketError{ErrorCode: 3}
+
 func NewCorruptedPacketError() CorruptedPacketError {
-	return CorruptedPacketError{}
+	return corruptedPacketErrorInstance
 }
 
 func (err CorruptedPacketError) Error() string {
-	return "[Error 0x0003] Corrupted packet."
+	return err.Prefix() + "Corrupted packet."
 }
 
 type IPFormatError struct {
+	ErrorCode
 	IP []byte
 }
 
 func NewIPFormatError(ip []byte) IPFormatError {
 	return IPFormatError{
-		IP: ip,
+		ErrorCode: 4,
+		IP:        ip,
 	}
 }
 
 func (err IPFormatError) Error() string {
-	return fmt.Sprintf("[Error 0x0004] Invalid IP %v", err.IP)
+	return fmt.Sprintf("%sInvalid IP %v", err.Prefix(), err.IP)
 }

common/errors/errors_test.go

@@ -0,0 +1,23 @@
+package errors_test
+
+import (
+	"testing"
+
+	"github.com/v2ray/v2ray-core/common/errors"
+	"github.com/v2ray/v2ray-core/testing/unit"
+)
+
+type MockError struct {
+	errors.ErrorCode
+}
+
+func (err MockError) Error() string {
+	return "This is a fake error."
+}
+
+func TestHasCode(t *testing.T) {
+	assert := unit.Assert(t)
+
+	err := MockError{ErrorCode: 101}
+	assert.Error(err).HasCode(101)
+}