package htlcswitch import ( "github.com/lightningnetwork/lnd/channeldb" "github.com/lightningnetwork/lnd/lnwire" "github.com/roasbeef/btcd/chaincfg/chainhash" "github.com/roasbeef/btcd/wire" ) // InvoiceDatabase is an interface which represents the persistent subsystem // which may search, lookup and settle invoices. type InvoiceDatabase interface { // LookupInvoice attempts to look up an invoice according to its 32 // byte payment hash. LookupInvoice(chainhash.Hash) (channeldb.Invoice, error) // SettleInvoice attempts to mark an invoice corresponding to the // passed payment hash as fully settled. SettleInvoice(chainhash.Hash) error } // ChannelLink is an interface which represents the subsystem for managing the // incoming htlc requests, applying the changes to the channel, and also // propagating/forwarding it to htlc switch. // // abstraction level // ^ // | // | - - - - - - - - - - - - Lightning - - - - - - - - - - - - - // | // | (Switch) (Switch) (Switch) // | Alice <-- channel link --> Bob <-- channel link --> Carol // | // | - - - - - - - - - - - - - TCP - - - - - - - - - - - - - - - // | // | (Peer) (Peer) (Peer) // | Alice <----- tcp conn --> Bob <---- tcp conn -----> Carol // | // type ChannelLink interface { // TODO(roasbeef): modify interface to embed mail boxes? // HandleSwitchPacket handles the switch packets. This packets might be // forwarded to us from another channel link in case the htlc update // came from another peer or if the update was created by user // initially. // // NOTE: This function MUST be non-blocking (or block as little as // possible). HandleSwitchPacket(*htlcPacket) error // HandleChannelUpdate handles the htlc requests as settle/add/fail // which sent to us from remote peer we have a channel with. // // NOTE: This function MUST be non-blocking (or block as little as // possible). HandleChannelUpdate(lnwire.Message) // ChanID returns the channel ID for the channel link. The channel ID // is a more compact representation of a channel's full outpoint. ChanID() lnwire.ChannelID // ShortChanID returns the short channel ID for the channel link. The // short channel ID encodes the exact location in the main chain that // the original funding output can be found. ShortChanID() lnwire.ShortChannelID // UpdateShortChanID updates the short channel ID for a link. This may // be required in the event that a link is created before the short // chan ID for it is known, or a re-org occurs, and the funding // transaction changes location within the chain. UpdateShortChanID() (lnwire.ShortChannelID, error) // UpdateForwardingPolicy updates the forwarding policy for the target // ChannelLink. Once updated, the link will use the new forwarding // policy to govern if it an incoming HTLC should be forwarded or not. UpdateForwardingPolicy(ForwardingPolicy) // HtlcSatifiesPolicy should return a nil error if the passed HTLC // details satisfy the current forwarding policy fo the target link. // Otherwise, a valid protocol failure message should be returned in // order to signal to the source of the HTLC, the policy consistency // issue. HtlcSatifiesPolicy(payHash [32]byte, incomingAmt, amtToForward lnwire.MilliSatoshi) lnwire.FailureMessage // Bandwidth returns the amount of milli-satoshis which current link // might pass through channel link. The value returned from this method // represents the up to date available flow through the channel. This // takes into account any forwarded but un-cleared HTLC's, and any // HTLC's which have been set to the over flow queue. Bandwidth() lnwire.MilliSatoshi // Stats return the statistics of channel link. Number of updates, // total sent/received milli-satoshis. Stats() (uint64, lnwire.MilliSatoshi, lnwire.MilliSatoshi) // Peer returns the representation of remote peer with which we have // the channel link opened. Peer() Peer // EligibleToForward returns a bool indicating if the channel is able // to actively accept requests to forward HTLC's. A channel may be // active, but not able to forward HTLC's if it hasn't yet finalized // the pre-channel operation protocol with the remote peer. The switch // will use this function in forwarding decisions accordingly. EligibleToForward() bool // AttachMailBox delivers an active MailBox to the link. The MailBox may // have buffered messages. AttachMailBox(MailBox) // Start/Stop are used to initiate the start/stop of the channel link // functioning. Start() error Stop() } // Peer is an interface which represents the remote lightning node inside our // system. type Peer interface { // SendMessage sends message to remote peer. The second argument // denotes if the method should block until the message has been sent // to the remote peer. SendMessage(msg lnwire.Message, sync bool) error // WipeChannel removes the channel uniquely identified by its channel // point from all indexes associated with the peer. WipeChannel(*wire.OutPoint) error // PubKey returns the serialize public key of the source peer. PubKey() [33]byte } // ForwardingLog is an interface that represents a time series database which // keep track of all successfully completed payment circuits. Every few // seconds, the switch will collate and flush out all the successful payment // circuits during the last interval. type ForwardingLog interface { // AddForwardingEvents is a method that should write out the set of // forwarding events in a batch to persistent storage. Outside // sub-systems can then query the contents of the log for analysis, // visualizations, etc. AddForwardingEvents([]channeldb.ForwardingEvent) error }