package channeldb import ( "bytes" "crypto/sha256" "fmt" "io" "time" "github.com/boltdb/bolt" "github.com/roasbeef/btcd/wire" "github.com/roasbeef/btcutil" ) var ( // invoiceBucket is the name of the bucket within the database that // stores all data related to invoices no matter their final state. // Within the invoice bucket, each invoice is keyed by its invoice ID // which is a monotonically increasing uint32. invoiceBucket = []byte("invoices") // paymentHashIndexBucket is the name of the sub-bucket within the // invoiceBucket which indexes all invoices by their payment hash. The // payment hash is the sha256 of the invoice's payment preimage. This // index is used to detect duplicates, and also to provide a fast path // for looking up incoming HTLCs to determine if we're able to settle // them fully. invoiceIndexBucket = []byte("paymenthashes") // numInvoicesKey is the name of key which houses the auto-incrementing // invoice ID which is essentially used as a primary key. With each // invoice inserted, the primary key is incremented by one. This key is // stored within the invoiceIndexBucket. Within the invoiceBucket // invoices are uniquely identified by the invoice ID. numInvoicesKey = []byte("nik") ) const ( // MaxMemoSize is maximum size of the memo field within invoices stored // in the database. MaxMemoSize = 1024 // MaxReceiptSize is the maximum size of the payment receipt stored // within the database along side incoming/outgoing invoices. MaxReceiptSize = 1024 ) // ContractTerm is a companion struct to the Invoice struct. This struct houses // the necessary conditions required before the invoice can be considered fully // settled by the payee. type ContractTerm struct { // PaymentPreimage is the preimage which is to be revealed in the // occasion that an HTLC paying to the hash of this preimage is // extended. PaymentPreimage [32]byte // Value is the expected amount to be payed to an HTLC which can be // satisfied by the above preimage. Value btcutil.Amount // Settled indicates if this particular contract term has been fully // settled by the payer. Settled bool } // Invoice is a payment invoice generated by a payee in order to request // payment for some good or service. The inclusion of invoices within Lightning // creates a payment work flow for merchants very similar to that of the // existing financial system within PayPal, etc. Invoices are added to the // database when a payment is requested, then can be settled manually once the // payment is received at the upper layer. For record keeping purposes, // invoices are never deleted from the database, instead a bit is toggled // denoting the invoice has been fully settled. Within the database, all // invoices must have a unique payment hash which is generated by taking the // sha256 of the payment // preimage. type Invoice struct { // Memo is an optional memo to be stored along side an invoice. The // memo may contain further details pertaining to the invoice itself, // or any other message which fits within the size constraints. Memo []byte // Receipt is an optional field dedicated for storing a // cryptographically binding receipt of payment. // // TODO(roasbeef): document scheme. Receipt []byte // CreationDate is the exact time the invoice was created. CreationDate time.Time // Terms are the contractual payment terms of the invoice. Once // all the terms have been satisfied by the payer, then the invoice can // be considered fully fulfilled. // // TODO(roasbeef): later allow for multiple terms to fulfill the final // invoice: payment fragmentation, etc. Terms ContractTerm } func validateInvoice(i *Invoice) error { if len(i.Memo) > MaxMemoSize { return fmt.Errorf("max length a memo is %v, and invoice "+ "of length %v was provided", MaxMemoSize, len(i.Memo)) } if len(i.Receipt) > MaxReceiptSize { return fmt.Errorf("max length a receipt is %v, and invoice "+ "of length %v was provided", MaxReceiptSize, len(i.Receipt)) } return nil } // AddInvoice inserts the targeted invoice into the database. If the invoice // has *any* payment hashes which already exists within the database, then the // insertion will be aborted and rejected due to the strict policy banning any // duplicate payment hashes. func (d *DB) AddInvoice(i *Invoice) error { if err := validateInvoice(i); err != nil { return err } return d.Update(func(tx *bolt.Tx) error { invoices, err := tx.CreateBucketIfNotExists(invoiceBucket) if err != nil { return err } invoiceIndex, err := invoices.CreateBucketIfNotExists(invoiceIndexBucket) if err != nil { return err } // Ensure that an invoice an identical payment hash doesn't // already exist within the index. paymentHash := sha256.Sum256(i.Terms.PaymentPreimage[:]) if invoiceIndex.Get(paymentHash[:]) != nil { return ErrDuplicateInvoice } // If the current running payment ID counter hasn't yet been // created, then create it now. var invoiceNum uint32 invoiceCounter := invoiceIndex.Get(numInvoicesKey) if invoiceCounter == nil { var scratch [4]byte byteOrder.PutUint32(scratch[:], invoiceNum) if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil { return nil } } else { invoiceNum = byteOrder.Uint32(invoiceCounter) } return putInvoice(invoices, invoiceIndex, i, invoiceNum) }) } // LookupInvoice attempts to look up an invoice according to it's 32 byte // payment hash. In an invoice which can settle the HTLC identified by the // passed payment hash isn't found, then an error is returned. Otherwise, the // full invoice is returned. Before setting the incoming HTLC, the values // SHOULD be checked to ensure the payer meets the agreed upon contractual // terms of the payment. func (d *DB) LookupInvoice(paymentHash [32]byte) (*Invoice, error) { var invoice *Invoice err := d.View(func(tx *bolt.Tx) error { invoices := tx.Bucket(invoiceBucket) if invoices == nil { return ErrNoInvoicesCreated } invoiceIndex := invoices.Bucket(invoiceIndexBucket) if invoiceIndex == nil { return ErrNoInvoicesCreated } // Check the invoice index to see if an invoice paying to this // hash exists within the DB. invoiceNum := invoiceIndex.Get(paymentHash[:]) if invoiceNum == nil { return ErrInvoiceNotFound } // An invoice matching the payment hash has been found, so // retrieve the record of the invoice itself. i, err := fetchInvoice(invoiceNum, invoices) if err != nil { return err } invoice = i return nil }) if err != nil { return nil, err } return invoice, nil } // FetchAllInvoices returns all invoices currently stored within the database. // If the pendingOnly param is true, then only unsettled invoices will be // returned, skipping all invoices that are fully settled. func (d *DB) FetchAllInvoices(pendingOnly bool) ([]*Invoice, error) { var invoices []*Invoice err := d.View(func(tx *bolt.Tx) error { invoiceB := tx.Bucket(invoiceBucket) if invoiceB == nil { return ErrNoInvoicesCreated } // Iterate through the entire key space of the top-level // invoice bucket. If key with a non-nil value stores the next // invoice ID which maps to the corresponding invoice. return invoiceB.ForEach(func(k, v []byte) error { if v == nil { return nil } invoiceReader := bytes.NewReader(v) invoice, err := deserializeInvoice(invoiceReader) if err != nil { return err } if pendingOnly && invoice.Terms.Settled { return nil } invoices = append(invoices, invoice) return nil }) }) if err != nil { return nil, err } return invoices, nil } // SettleInvoice attempts to mark an invoice corresponding to the passed // payment hash as fully settled. If an invoice matching the passed payment // hash doesn't existing within the database, then the action will fail with a // "not found" error. func (d *DB) SettleInvoice(paymentHash [32]byte) error { return d.Update(func(tx *bolt.Tx) error { invoices, err := tx.CreateBucketIfNotExists(invoiceBucket) if err != nil { return err } invoiceIndex, err := invoices.CreateBucketIfNotExists(invoiceIndexBucket) if err != nil { return err } // Check the invoice index to see if an invoice paying to this // hash exists within the DB. invoiceNum := invoiceIndex.Get(paymentHash[:]) if invoiceNum == nil { return ErrInvoiceNotFound } return settleInvoice(invoices, invoiceNum) }) } func putInvoice(invoices *bolt.Bucket, invoiceIndex *bolt.Bucket, i *Invoice, invoiceNum uint32) error { // Create the invoice key which is just the big-endian representation // of the invoice number. var invoiceKey [4]byte byteOrder.PutUint32(invoiceKey[:], invoiceNum) // Increment the num invoice counter index so the next invoice bares // the proper ID. var scratch [4]byte invoiceCounter := invoiceNum + 1 byteOrder.PutUint32(scratch[:], invoiceCounter) if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil { return err } // Add the payment hash to the invoice index. This'll let us quickly // identify if we can settle an incoming payment, and also to possibly // allow a single invoice to have multiple payment installations. paymentHash := sha256.Sum256(i.Terms.PaymentPreimage[:]) if err := invoiceIndex.Put(paymentHash[:], invoiceKey[:]); err != nil { return err } // Finally, serialize the invoice itself to be written to the disk. var buf bytes.Buffer if err := serializeInvoice(&buf, i); err != nil { return nil } return invoices.Put(invoiceKey[:], buf.Bytes()) } func serializeInvoice(w io.Writer, i *Invoice) error { if err := wire.WriteVarBytes(w, 0, i.Memo[:]); err != nil { return err } if err := wire.WriteVarBytes(w, 0, i.Receipt[:]); err != nil { return err } birthBytes, err := i.CreationDate.MarshalBinary() if err != nil { return err } if err := wire.WriteVarBytes(w, 0, birthBytes); err != nil { return err } if _, err := w.Write(i.Terms.PaymentPreimage[:]); err != nil { return err } var scratch [8]byte byteOrder.PutUint64(scratch[:], uint64(i.Terms.Value)) if _, err := w.Write(scratch[:]); err != nil { return err } var settleByte [1]byte if i.Terms.Settled { settleByte[0] = 1 } if _, err := w.Write(settleByte[:]); err != nil { return err } return nil } func fetchInvoice(invoiceNum []byte, invoices *bolt.Bucket) (*Invoice, error) { invoiceBytes := invoices.Get(invoiceNum) if invoiceBytes == nil { return nil, ErrInvoiceNotFound } invoiceReader := bytes.NewReader(invoiceBytes) return deserializeInvoice(invoiceReader) } func deserializeInvoice(r io.Reader) (*Invoice, error) { var err error invoice := &Invoice{} // TODO(roasbeef): use read full everywhere invoice.Memo, err = wire.ReadVarBytes(r, 0, MaxMemoSize, "") if err != nil { return nil, err } invoice.Receipt, err = wire.ReadVarBytes(r, 0, MaxReceiptSize, "") if err != nil { return nil, err } birthBytes, err := wire.ReadVarBytes(r, 0, 300, "birth") if err != nil { return nil, err } if err := invoice.CreationDate.UnmarshalBinary(birthBytes); err != nil { return nil, err } if _, err := io.ReadFull(r, invoice.Terms.PaymentPreimage[:]); err != nil { return nil, err } var scratch [8]byte if _, err := io.ReadFull(r, scratch[:]); err != nil { return nil, err } invoice.Terms.Value = btcutil.Amount(byteOrder.Uint64(scratch[:])) var settleByte [1]byte if _, err := io.ReadFull(r, settleByte[:]); err != nil { return nil, err } if settleByte[0] == 1 { invoice.Terms.Settled = true } return invoice, nil } func settleInvoice(invoices *bolt.Bucket, invoiceNum []byte) error { invoice, err := fetchInvoice(invoiceNum, invoices) if err != nil { return err } invoice.Terms.Settled = true var buf bytes.Buffer if err := serializeInvoice(&buf, invoice); err != nil { return nil } return invoices.Put(invoiceNum[:], buf.Bytes()) }