lnd.xprv/lnwire/htlc_addrequest.go

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package lnwire
import (
"fmt"
"io"
"github.com/roasbeef/btcd/wire"
)
// HTLCAddRequest is the message sent by Alice to Bob when she wishes to add an
// HTLC to his remote commitment transaction. In addition to information
// detailing the value, and contract type of the HTLC, and onion blob is also
// included which allows Bob to derive the next hop in the route. The HTLC
// added by this message is to be added to the remote node's "pending" HTLC's.
// A subsequent CommitSignature message will move the pending HTLC to the newly
// created commitment transaction, marking them as "staged".
type HTLCAddRequest struct {
// ChannelPoint is the particular active channel that this HTLCAddRequest
// is binded to.
ChannelPoint *wire.OutPoint
// Expiry is the number of blocks after which this HTLC should expire.
// It is the receiver's duty to ensure that the outgoing HTLC has a
// sufficient expiry value to allow her to redeem the incmoing HTLC.
Expiry uint32
// Amount to pay in the hop
// Difference between hop and first item in blob is the fee to complete
// Amount is the number of credits this HTLC is worth.
Amount CreditsAmount
// RefundContext is for payment cancellation
// TODO(j): not currently in use, add later
RefundContext HTLCKey
// ContractType defines the particular output script to be used for
// this HTLC. This value defaults to zero for regular HTLCs. For
// multi-sig HTLCs, then first 4 bit represents N, while the second 4
// bits are M, within the N-of-M multi-sig.
ContractType uint8
// RedemptionHashes are the hashes to be used within the HTLC script.
// An HTLC is only fufilled once Bob is provided with the required
// number of pre-images for each of the listed hashes. For regular HTLC's
// this slice only has one hash. However, for "multi-sig" HTLC's, the
// length of this slice should be N.
RedemptionHashes [][32]byte
// OnionBlob is the raw serialized mix header used to route an HTLC in
// a privacy-preserving manner. The mix header is defined currently to
// be parsed as a 4-tuple: (groupElement, routingInfo, headerMAC, body).
// First the receiving node should use the groupElement, and its current
// onion key to derive a shared secret with the source. Once the shared
// secret has been derived, the headerMAC should be checked FIRST. Note
// that the MAC only covers the routingInfo field. If the MAC matches,
// and the shared secret is fresh, then the node should stip off a layer
// of encryption, exposing the next hop to be used in the subsequent
// HTLCAddRequest message.
OnionBlob []byte
}
// NewHTLCAddRequest returns a new empty HTLCAddRequest message.
func NewHTLCAddRequest() *HTLCAddRequest {
return &HTLCAddRequest{}
}
// A compile time check to ensure HTLCAddRequest implements the lnwire.Message
// interface.
var _ Message = (*HTLCAddRequest)(nil)
// Decode deserializes a serialized HTLCAddRequest message stored in the passed
// io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *HTLCAddRequest) Decode(r io.Reader, pver uint32) error {
// ChannelPoint(8)
// Expiry(4)
// Amount(4)
// ContractType(1)
// RedemptionHashes (numOfHashes * 32 + numOfHashes)
// OnionBlog
err := readElements(r,
&c.ChannelPoint,
&c.Expiry,
&c.Amount,
&c.ContractType,
&c.RedemptionHashes,
&c.OnionBlob,
)
if err != nil {
return err
}
return nil
}
// Encode serializes the target HTLCAddRequest into the passed io.Writer observing
// the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *HTLCAddRequest) Encode(w io.Writer, pver uint32) error {
err := writeElements(w,
c.ChannelPoint,
c.Expiry,
c.Amount,
c.ContractType,
c.RedemptionHashes,
c.OnionBlob,
)
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 *HTLCAddRequest) Command() uint32 {
return CmdHTLCAddRequest
}
// MaxPayloadLength returns the maximum allowed payload size for a HTLCAddRequest
// complete message observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *HTLCAddRequest) MaxPayloadLength(uint32) uint32 {
// base size ~110, but blob can be variable.
// shouldn't be bigger than 8K though...
return 8192
}
// Validate performs any necessary sanity checks to ensure all fields present
// on the HTLCAddRequest are valid.
//
// This is part of the lnwire.Message interface.
func (c *HTLCAddRequest) Validate() error {
if c.Amount < 0 {
// While fees can be negative, it's too confusing to allow
// negative payments. Maybe for some wallets, but not this one!
return fmt.Errorf("Amount paid cannot be negative.")
}
// We're good!
return nil
}
// String returns the string representation of the target HTLCAddRequest.
//
// This is part of the lnwire.Message interface.
func (c *HTLCAddRequest) String() string {
var redemptionHashes string
for i, rh := range c.RedemptionHashes {
redemptionHashes += fmt.Sprintf("\n\tSlice\t%d\n", i)
redemptionHashes += fmt.Sprintf("\t\tRedemption Hash: %x\n", rh)
}
return fmt.Sprintf("\n--- Begin HTLCAddRequest ---\n") +
fmt.Sprintf("ChannelPoint:\t%v\n", c.ChannelPoint) +
fmt.Sprintf("Expiry:\t\t%d\n", c.Expiry) +
fmt.Sprintf("Amount\t\t%d\n", c.Amount) +
fmt.Sprintf("ContractType:\t%d (%b)\n", c.ContractType, c.ContractType) +
fmt.Sprintf("RedemptionHashes:") +
redemptionHashes +
fmt.Sprintf("OnionBlob:\t\t\t\t%x\n", c.OnionBlob) +
fmt.Sprintf("--- End HTLCAddRequest ---\n")
}