lnd.xprv/lnwire/htlc_cancel.go

166 lines
4.5 KiB
Go
Raw Normal View History

package lnwire
import (
"fmt"
"io"
"github.com/roasbeef/btcd/wire"
)
// CancelReason specifies the precise reason that an upstream HTLC was
// cancelled. Each CancelHTLC message carries a CancelReason which is to be
// passed back unaltered to the source of the HTLC within the route.
//
// TODO(roasbeef): implement proper encrypted error messages as defined in spec
// * these errors as it stands reveal the error cause to all links in the
// route and are horrible for privacy
type CancelReason uint16
const (
// InsufficientCapacity indicates that a payment failed due to a link
// in the ultimate route not having enough satoshi flow to successfully
// carry the payment.
InsufficientCapacity = 0
// UpstreamTimeout indicates that an upstream link had to enforce the
// absolute HTLC timeout, removing the HTLC.
UpstreamTimeout = 1
// UnkownPaymentHash indicates that the destination did not recognize
// the payment hash.
UnkownPaymentHash = 2
// UnkownDestination indicates that the specified next hop within the
// Sphinx packet at a point in the route contained an unknown or
// invalid "next hop".
UnkownDestination = 3
// SphinxParseError indicates that an intermediate node was unable
// properly parse the HTLC.
SphinxParseError = 4
)
// String returns a human-readable version of the CancelReason type.
func (c CancelReason) String() string {
switch c {
case InsufficientCapacity:
return "InsufficientCapacity: next hop had insufficient " +
"capacity for payment"
case UpstreamTimeout:
return "UpstreamTimeout: HTLC has timed out upstream"
case UnkownPaymentHash:
return "UnkownPaymentHash: the destination did not know the " +
"preimage"
case UnkownDestination:
return "UnkownDestination: next hop unknown"
case SphinxParseError:
return "SphinxParseError: unable to parse sphinx packet"
default:
return "unknown reason"
}
}
// CancelHTLC is sent by Alice to Bob in order to remove a previously added
// HTLC. Upon receipt of an CancelHTLC the HTLC should be removed from the next
// commitment transaction, with the CancelHTLC propagated backwards in the
// route to fully un-clear the HTLC.
type CancelHTLC struct {
// ChannelPoint is the particular active channel that this CancelHTLC
// is binded to.
ChannelPoint *wire.OutPoint
// HTLCKey references which HTLC on the remote node's commitment
// transaction has timed out.
HTLCKey HTLCKey
// Reason described the event that caused the HTLC to be cancelled
// within the route.
Reason CancelReason
}
// Decode deserializes a serialized CancelHTLC message stored in the passed
// io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *CancelHTLC) Decode(r io.Reader, pver uint32) error {
// ChannelPoint(8)
// HTLCKey(8)
err := readElements(r,
&c.ChannelPoint,
&c.HTLCKey,
&c.Reason,
)
if err != nil {
return err
}
return nil
}
// CancelHTLC creates a new CancelHTLC message.
func NewHTLCTimeoutRequest() *CancelHTLC {
return &CancelHTLC{}
}
// A compile time check to ensure CancelHTLC implements the lnwire.Message
// interface.
var _ Message = (*CancelHTLC)(nil)
// Encode serializes the target CancelHTLC into the passed io.Writer observing
// the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *CancelHTLC) Encode(w io.Writer, pver uint32) error {
err := writeElements(w,
c.ChannelPoint,
c.HTLCKey,
c.Reason,
)
if err != nil {
return err
}
return nil
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (c *CancelHTLC) Command() uint32 {
return CmdCancelHTLC
}
// MaxPayloadLength returns the maximum allowed payload size for a CancelHTLC
// complete message observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *CancelHTLC) MaxPayloadLength(uint32) uint32 {
// 36 + 8 + 2
return 46
}
// Validate performs any necessary sanity checks to ensure all fields present
// on the CancelHTLC are valid.
//
// This is part of the lnwire.Message interface.
func (c *CancelHTLC) Validate() error {
// We're good!
return nil
}
// String returns the string representation of the target CancelHTLC. This is
// part of the lnwire.Message interface.
func (c *CancelHTLC) String() string {
return fmt.Sprintf("\n--- Begin CancelHTLC ---\n") +
fmt.Sprintf("ChannelPoint:\t%d\n", c.ChannelPoint) +
fmt.Sprintf("HTLCKey:\t%d\n", c.HTLCKey) +
fmt.Sprintf("Reason:\t%v\n", c.Reason) +
fmt.Sprintf("--- End CancelHTLC ---\n")
}