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