lnd.xprv/htlcswitch/failure.go

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package htlcswitch
import (
"bytes"
"fmt"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/htlcswitch/hop"
"github.com/lightningnetwork/lnd/lnwire"
)
// ClearTextError is an interface which is implemented by errors that occur
// when we know the underlying wire failure message. These errors are the
// opposite to opaque errors which are onion-encrypted blobs only understandable
// to the initiating node. ClearTextErrors are used when we fail a htlc at our
// node, or one of our initiated payments failed and we can decrypt the onion
// encrypted error fully.
type ClearTextError interface {
error
// WireMessage extracts a valid wire failure message from an internal
// error which may contain additional metadata (which should not be
// exposed to the network). This value may be nil in the case where
// an unknown wire error is returned by one of our peers.
WireMessage() lnwire.FailureMessage
}
// LinkError is an implementation of the ClearTextError interface which
// represents failures that occur on our incoming or outgoing link.
type LinkError struct {
// msg returns the wire failure associated with the error.
// This value should *not* be nil, because we should always
// know the failure type for failures which occur at our own
// node.
msg lnwire.FailureMessage
// FailureDetail enriches the wire error with additional information.
FailureDetail
}
// NewLinkError returns a LinkError with the failure message provided.
// The failure message provided should *not* be nil, because we should
// always know the failure type for failures which occur at our own node.
func NewLinkError(msg lnwire.FailureMessage) *LinkError {
return &LinkError{msg: msg}
}
// NewDetailedLinkError returns a link error that enriches a wire message with
// a failure detail.
func NewDetailedLinkError(msg lnwire.FailureMessage,
detail FailureDetail) *LinkError {
return &LinkError{
msg: msg,
FailureDetail: detail,
}
}
// WireMessage extracts a valid wire failure message from an internal
// error which may contain additional metadata (which should not be
// exposed to the network). This value should never be nil for LinkErrors,
// because we are the ones failing the htlc.
//
// Note this is part of the ClearTextError interface.
func (l *LinkError) WireMessage() lnwire.FailureMessage {
return l.msg
}
// Error returns the string representation of a link error.
//
// Note this is part of the ClearTextError interface.
func (l *LinkError) Error() string {
// If the link error has no failure detail, return the wire message's
// error.
if l.FailureDetail == FailureDetailNone {
return l.msg.Error()
}
return fmt.Sprintf("%v: %v", l.msg.Error(), l.FailureDetail)
}
// ForwardingError wraps an lnwire.FailureMessage in a struct that also
// includes the source of the error.
type ForwardingError struct {
// FailureSourceIdx is the index of the node that sent the failure. With
// this information, the dispatcher of a payment can modify their set of
// candidate routes in response to the type of failure extracted. Index
// zero is the self node.
FailureSourceIdx int
// msg is the wire message associated with the error. This value may
// be nil in the case where we fail to decode failure message sent by
// a peer.
msg lnwire.FailureMessage
}
// WireMessage extracts a valid wire failure message from an internal
// error which may contain additional metadata (which should not be
// exposed to the network). This value may be nil in the case where
// an unknown wire error is returned by one of our peers.
//
// Note this is part of the ClearTextError interface.
func (f *ForwardingError) WireMessage() lnwire.FailureMessage {
return f.msg
}
// Error implements the built-in error interface. We use this method to allow
// the switch or any callers to insert additional context to the error message
// returned.
func (f *ForwardingError) Error() string {
return fmt.Sprintf(
"%v@%v", f.msg, f.FailureSourceIdx,
)
}
// NewForwardingError creates a new payment error which wraps a wire error
// with additional metadata.
func NewForwardingError(failure lnwire.FailureMessage,
index int) *ForwardingError {
return &ForwardingError{
FailureSourceIdx: index,
msg: failure,
}
}
// NewUnknownForwardingError returns a forwarding error which has a nil failure
// message. This constructor should only be used in the case where we cannot
// decode the failure we have received from a peer.
func NewUnknownForwardingError(index int) *ForwardingError {
return &ForwardingError{
FailureSourceIdx: index,
}
}
// ErrorDecrypter is an interface that is used to decrypt the onion encrypted
// failure reason an extra out a well formed error.
type ErrorDecrypter interface {
// DecryptError peels off each layer of onion encryption from the first
// hop, to the source of the error. A fully populated
// lnwire.FailureMessage is returned along with the source of the
// error.
DecryptError(lnwire.OpaqueReason) (*ForwardingError, error)
}
// UnknownEncrypterType is an error message used to signal that an unexpected
// EncrypterType was encountered during decoding.
type UnknownEncrypterType hop.EncrypterType
// Error returns a formatted error indicating the invalid EncrypterType.
func (e UnknownEncrypterType) Error() string {
return fmt.Sprintf("unknown error encrypter type: %d", e)
}
// OnionErrorDecrypter is the interface that provides onion level error
// decryption.
type OnionErrorDecrypter interface {
// DecryptError attempts to decrypt the passed encrypted error response.
// The onion failure is encrypted in backward manner, starting from the
// node where error have occurred. As a result, in order to decrypt the
// error we need get all shared secret and apply decryption in the
// reverse order.
DecryptError(encryptedData []byte) (*sphinx.DecryptedError, error)
}
// SphinxErrorDecrypter wraps the sphinx data SphinxErrorDecrypter and maps the
// returned errors to concrete lnwire.FailureMessage instances.
type SphinxErrorDecrypter struct {
OnionErrorDecrypter
}
// DecryptError peels off each layer of onion encryption from the first hop, to
// the source of the error. A fully populated lnwire.FailureMessage is returned
// along with the source of the error.
//
// NOTE: Part of the ErrorDecrypter interface.
func (s *SphinxErrorDecrypter) DecryptError(reason lnwire.OpaqueReason) (
*ForwardingError, error) {
failure, err := s.OnionErrorDecrypter.DecryptError(reason)
if err != nil {
return nil, err
}
// Decode the failure. If an error occurs, we leave the failure message
// field nil.
r := bytes.NewReader(failure.Message)
failureMsg, err := lnwire.DecodeFailure(r, 0)
if err != nil {
return NewUnknownForwardingError(failure.SenderIdx), nil
}
return NewForwardingError(failureMsg, failure.SenderIdx), nil
}
// A compile time check to ensure ErrorDecrypter implements the Deobfuscator
// interface.
var _ ErrorDecrypter = (*SphinxErrorDecrypter)(nil)