attributes: rename files

errorcode.go

@@ -0,0 +1,95 @@
+package stun
+
+import "errors"
+
+// ErrorCodeAttribute represents ERROR-CODE attribute.
+type ErrorCodeAttribute struct {
+	Code   ErrorCode
+	Reason []byte
+}
+
+// constants for ERROR-CODE encoding.
+const (
+	errorCodeReasonStart = 4
+	errorCodeClassByte   = 2
+	errorCodeNumberByte  = 3
+	errorCodeReasonMaxB  = 763
+	errorCodeModulo      = 100
+)
+
+// ErrReasonLengthTooBig means that len(Reason) > 763 bytes.
+var ErrReasonLengthTooBig = errors.New("reason for ERROR-CODE is too big")
+
+// AddTo adds ERROR-CODE to m.
+func (c *ErrorCodeAttribute) AddTo(m *Message) error {
+	value := make([]byte, 0, errorCodeReasonMaxB)
+	if len(c.Reason) > errorCodeReasonMaxB {
+		return ErrReasonLengthTooBig
+	}
+	value = value[:errorCodeReasonStart+len(c.Reason)]
+	number := byte(c.Code % errorCodeModulo) // error code modulo 100
+	class := byte(c.Code / errorCodeModulo)  // hundred digit
+	value[errorCodeClassByte] = class
+	value[errorCodeNumberByte] = number
+	copy(value[errorCodeReasonStart:], c.Reason)
+	m.Add(AttrErrorCode, value)
+	return nil
+}
+
+// GetFrom decodes ERROR-CODE from m. Reason is valid until m.Raw is valid.
+func (c *ErrorCodeAttribute) GetFrom(m *Message) error {
+	v, err := m.Get(AttrErrorCode)
+	if err != nil {
+		return err
+	}
+	var (
+		class  = uint16(v[errorCodeClassByte])
+		number = uint16(v[errorCodeNumberByte])
+		code   = int(class*errorCodeModulo + number)
+	)
+	c.Code = ErrorCode(code)
+	c.Reason = v[errorCodeReasonStart:]
+	return nil
+}
+
+// ErrorCode is code for ERROR-CODE attribute.
+type ErrorCode int
+
+// ErrNoDefaultReason means that default reason for provided error code
+// is not defined in RFC.
+var ErrNoDefaultReason = errors.New("No default reason for ErrorCode")
+
+// AddTo adds ERROR-CODE with default reason to m. If there
+// is no default reason, returns ErrNoDefaultReason.
+func (c ErrorCode) AddTo(m *Message) error {
+	reason := errorReasons[c]
+	if reason == nil {
+		return ErrNoDefaultReason
+	}
+	a := &ErrorCodeAttribute{
+		Code:   c,
+		Reason: reason,
+	}
+	return a.AddTo(m)
+}
+
+// Possible error codes.
+const (
+	CodeTryAlternate     ErrorCode = 300
+	CodeBadRequest       ErrorCode = 400
+	CodeUnauthorised     ErrorCode = 401
+	CodeUnknownAttribute ErrorCode = 420
+	CodeStaleNonce       ErrorCode = 428
+	CodeRoleConflict     ErrorCode = 478
+	CodeServerError      ErrorCode = 500
+)
+
+var errorReasons = map[ErrorCode][]byte{
+	CodeTryAlternate:     []byte("Try Alternate"),
+	CodeBadRequest:       []byte("Bad Request"),
+	CodeUnauthorised:     []byte("Unauthorised"),
+	CodeUnknownAttribute: []byte("Unknown Attribute"),
+	CodeStaleNonce:       []byte("Stale Nonce"),
+	CodeServerError:      []byte("Server Error"),
+	CodeRoleConflict:     []byte("Role Conflict"),
+}