107 lines
3.5 KiB
Go
107 lines
3.5 KiB
Go
package htlcswitch
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import (
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"bytes"
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"fmt"
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sphinx "github.com/lightningnetwork/lightning-onion"
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"github.com/lightningnetwork/lnd/htlcswitch/hop"
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"github.com/lightningnetwork/lnd/lnwire"
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)
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// ForwardingError wraps an lnwire.FailureMessage in a struct that also
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// includes the source of the error.
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type ForwardingError struct {
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// FailureSourceIdx is the index of the node that sent the failure. With
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// this information, the dispatcher of a payment can modify their set of
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// candidate routes in response to the type of failure extracted. Index
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// zero is the self node.
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FailureSourceIdx int
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// ExtraMsg is an additional error message that callers can provide in
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// order to provide context specific error details.
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ExtraMsg string
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lnwire.FailureMessage
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}
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// Error implements the built-in error interface. We use this method to allow
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// the switch or any callers to insert additional context to the error message
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// returned.
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func (f *ForwardingError) Error() string {
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if f.ExtraMsg == "" {
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return fmt.Sprintf("%v", f.FailureMessage)
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}
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return fmt.Sprintf("%v: %v", f.FailureMessage, f.ExtraMsg)
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}
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// ErrorDecrypter is an interface that is used to decrypt the onion encrypted
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// failure reason an extra out a well formed error.
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type ErrorDecrypter interface {
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// DecryptError peels off each layer of onion encryption from the first
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// hop, to the source of the error. A fully populated
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// lnwire.FailureMessage is returned along with the source of the
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// error.
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DecryptError(lnwire.OpaqueReason) (*ForwardingError, error)
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}
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// UnknownEncrypterType is an error message used to signal that an unexpected
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// EncrypterType was encountered during decoding.
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type UnknownEncrypterType hop.EncrypterType
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// Error returns a formatted error indicating the invalid EncrypterType.
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func (e UnknownEncrypterType) Error() string {
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return fmt.Sprintf("unknown error encrypter type: %d", e)
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}
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// OnionErrorDecrypter is the interface that provides onion level error
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// decryption.
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type OnionErrorDecrypter interface {
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// DecryptError attempts to decrypt the passed encrypted error response.
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// The onion failure is encrypted in backward manner, starting from the
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// node where error have occurred. As a result, in order to decrypt the
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// error we need get all shared secret and apply decryption in the
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// reverse order.
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DecryptError(encryptedData []byte) (*sphinx.DecryptedError, error)
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}
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// SphinxErrorDecrypter wraps the sphinx data SphinxErrorDecrypter and maps the
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// returned errors to concrete lnwire.FailureMessage instances.
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type SphinxErrorDecrypter struct {
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OnionErrorDecrypter
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}
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// DecryptError peels off each layer of onion encryption from the first hop, to
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// the source of the error. A fully populated lnwire.FailureMessage is returned
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// along with the source of the error.
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//
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// NOTE: Part of the ErrorDecrypter interface.
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func (s *SphinxErrorDecrypter) DecryptError(reason lnwire.OpaqueReason) (
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*ForwardingError, error) {
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failure, err := s.OnionErrorDecrypter.DecryptError(reason)
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if err != nil {
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return nil, err
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}
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// Decode the failure. If an error occurs, we leave the failure message
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// field nil.
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r := bytes.NewReader(failure.Message)
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failureMsg, err := lnwire.DecodeFailure(r, 0)
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if err != nil {
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return &ForwardingError{
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FailureSourceIdx: failure.SenderIdx,
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}, nil
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}
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return &ForwardingError{
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FailureSourceIdx: failure.SenderIdx,
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FailureMessage: failureMsg,
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}, nil
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}
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// A compile time check to ensure ErrorDecrypter implements the Deobfuscator
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// interface.
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var _ ErrorDecrypter = (*SphinxErrorDecrypter)(nil)
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