134 lines
4.3 KiB
Go
134 lines
4.3 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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"github.com/roasbeef/btcutil"
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)
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// OnionPacketSize is the size of the serialized Sphinx onion packet included
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// in each UpdateAddHTLC message.
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const OnionPacketSize = 1254
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// UpdateAddHTLC 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, the ID, expiry, and the onion blob is also included
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// which allows Bob to derive the next hop in the route. The HTLC added by this
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// message is to be added to the remote node's "pending" HTLC's. A subsequent
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// CommitSig message will move the pending HTLC to the newly created commitment
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// transaction, marking them as "staged".
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type UpdateAddHTLC struct {
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// ChannelPoint is the particular active channel that this
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// UpdateAddHTLC is binded to.
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ChannelPoint wire.OutPoint
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// ID is the identification server for this HTLC. This value is
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// explicitly included as it allows nodes to survive single-sided
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// restarts. The ID value for this sides starts at zero, and increases
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// with each offered HTLC.
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ID uint64
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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 incoming HTLC.
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Expiry uint32
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// Amount is the amount of satoshis this HTLC is worth.
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Amount btcutil.Amount
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// PaymentHash is the payment hash to be included in the HTLC this
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// request creates. The pre-image to this HTLC must be revelaed by the
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// upstream peer in order to fully settle the HTLC.
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PaymentHash [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,
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// body). First the receiving node should use the groupElement, and
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// its current onion key to derive a shared secret with the source.
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// Once the shared secret has been derived, the headerMAC should be
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// checked FIRST. Note that the MAC only covers the routingInfo field.
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// If the MAC matches, and the shared secret is fresh, then the node
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// should strip off a layer of encryption, exposing the next hop to be
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// used in the subsequent UpdateAddHTLC message.
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OnionBlob [OnionPacketSize]byte
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}
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// NewUpdateAddHTLC returns a new empty UpdateAddHTLC message.
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func NewUpdateAddHTLC() *UpdateAddHTLC {
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return &UpdateAddHTLC{}
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}
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// A compile time check to ensure UpdateAddHTLC implements the lnwire.Message
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// interface.
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var _ Message = (*UpdateAddHTLC)(nil)
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// Decode deserializes a serialized UpdateAddHTLC 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 *UpdateAddHTLC) Decode(r io.Reader, pver uint32) error {
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// ChannelPoint(8)
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// ID(4)
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// Expiry(4)
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// Amount(8)
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// PaymentHash(32)
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// OnionBlob(1254)
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return readElements(r,
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&c.ChannelPoint,
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&c.ID,
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&c.Expiry,
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&c.Amount,
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c.PaymentHash[:],
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c.OnionBlob[:],
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)
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}
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// Encode serializes the target UpdateAddHTLC 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 *UpdateAddHTLC) Encode(w io.Writer, pver uint32) error {
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return writeElements(w,
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c.ChannelPoint,
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c.ID,
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c.Expiry,
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c.Amount,
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c.PaymentHash[:],
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c.OnionBlob[:],
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)
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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 *UpdateAddHTLC) Command() uint32 {
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return CmdUpdateAddHTLC
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}
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// MaxPayloadLength returns the maximum allowed payload size for a UpdateAddHTLC
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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 *UpdateAddHTLC) MaxPayloadLength(uint32) uint32 {
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// 1342
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return 36 + 8 + 4 + 8 + 32 + 1254
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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 UpdateAddHTLC are valid.
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//
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// This is part of the lnwire.Message interface.
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func (c *UpdateAddHTLC) 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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