[wip] Initial v2 cut

1 files changed, 91 insertions, 0 deletions

diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..479161a
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,91 @@
+package securecookie
+
+import "strings"
+
+// Error is the interface of all errors returned by functions in this library.
+type Error interface {
+	error
+
+	// IsUsage returns true for errors indicating the client code probably
+	// uses this library incorrectly.  For example, the client may have
+	// failed to provide a valid hash key, or may have failed to configure
+	// the Serializer adequately for encoding value.
+	IsUsage() bool
+
+	// IsDecode returns true for errors indicating that a cookie could not
+	// be decoded and validated.  Since cookies are usually untrusted
+	// user-provided input, errors of this type should be expected.
+	// Usually, the proper action is simply to reject the request.
+	IsDecode() bool
+
+	// IsInternal returns true for unexpected errors occurring in the
+	// securecookie implementation.
+	IsInternal() bool
+
+	// Cause, if it returns a non-nil value, indicates that this error was
+	// propagated from some underlying library.  If this method returns nil,
+	// this error was raised directly by this library.
+	//
+	// Cause is provided principally for debugging/logging purposes; it is
+	// rare that application logic should perform meaningfully different
+	// logic based on Cause.  See, for example, the caveats described on
+	// (MultiError).Cause().
+	Cause() error
+}
+
+// errorType is a bitmask giving the error type(s) of an cookieError value.
+type errorType int
+
+const (
+	usageError = errorType(1 << iota)
+	decodeError
+	internalError
+)
+
+type cookieError struct {
+	typ   errorType
+	msg   string
+	cause error
+}
+
+func (e cookieError) IsUsage() bool    { return (e.typ & usageError) != 0 }
+func (e cookieError) IsDecode() bool   { return (e.typ & decodeError) != 0 }
+func (e cookieError) IsInternal() bool { return (e.typ & internalError) != 0 }
+
+func (e cookieError) Cause() error { return e.cause }
+
+func (e cookieError) Error() string {
+	parts := []string{"securecookie: "}
+	if e.msg == "" {
+		parts = append(parts, "error")
+	} else {
+		parts = append(parts, e.msg)
+	}
+	if c := e.Cause(); c != nil {
+		parts = append(parts, " - caused by: ", c.Error())
+	}
+	return strings.Join(parts, "")
+}
+
+var (
+	errGeneratingIV = cookieError{typ: internalError, msg: "failed to generate random iv"}
+
+	errNoCodecs            = cookieError{typ: usageError, msg: "no codecs provided"}
+	errHashKeyNotSet       = cookieError{typ: usageError, msg: "hash key is not set"}
+	errBlockKeyNotSet      = cookieError{typ: usageError, msg: "block key is not set"}
+	errEncodedValueTooLong = cookieError{typ: usageError, msg: "the value is too long"}
+
+	errValueToDecodeTooLong = cookieError{typ: decodeError, msg: "the value is too long"}
+	errTimestampInvalid     = cookieError{typ: decodeError, msg: "invalid timestamp"}
+	errTimestampTooNew      = cookieError{typ: decodeError, msg: "timestamp is too new"}
+	errTimestampExpired     = cookieError{typ: decodeError, msg: "expired timestamp"}
+	errDecryptionFailed     = cookieError{typ: decodeError, msg: "the value could not be decrypted"}
+	errValueNotByte         = cookieError{typ: decodeError, msg: "value not a []byte."}
+
+	// ErrMacInvalid indicates that cookie decoding failed because the HMAC
+	// could not be extracted and verified.  Direct use of this error
+	// variable is deprecated; it is public only for legacy compatibility,
+	// and may be privatized in the future, as it is rarely useful to
+	// distinguish between this error and other Error implementations.
+	ErrMacInvalid = cookieError{typ: decodeError, msg: "the value is not valid"}
+)