Add HTTP_1_1_REQUIRED error code.

errors.go

@@ -24,6 +24,7 @@ const (
 	ErrCodeConnect            ErrCode = 0xa
 	ErrCodeEnhanceYourCalm    ErrCode = 0xb
 	ErrCodeInadequateSecurity ErrCode = 0xc
+	ErrCodeHTTP11Required     ErrCode = 0xd
 )
 
 var errCodeName = map[ErrCode]string{
@@ -40,6 +41,7 @@ var errCodeName = map[ErrCode]string{
 	ErrCodeConnect:            "CONNECT_ERROR",
 	ErrCodeEnhanceYourCalm:    "ENHANCE_YOUR_CALM",
 	ErrCodeInadequateSecurity: "INADEQUATE_SECURITY",
+	ErrCodeHTTP11Required:     "HTTP_1_1_REQUIRED",
 }
 
 func (e ErrCode) String() string {

errors_test.go

@@ -15,6 +15,7 @@ func TestErrCodeString(t *testing.T) {
 		want string
 	}{
 		{ErrCodeProtocol, "PROTOCOL_ERROR"},
+		{0xd, "HTTP_1_1_REQUIRED"},
 		{0xf, "unknown error code 0xf"},
 	}
 	for i, tt := range tests {