Merge pull request #155 from Roasbeef/psbt-refactor

psbt: refactor new PSBT library to match code style of project

go.mod

@@ -0,0 +1,11 @@
+module github.com/btcsuite/btcutil
+
+go 1.13
+
+require (
+	github.com/aead/siphash v1.0.1
+	github.com/btcsuite/btcd v0.20.1-beta
+	github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495
+	github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23
+	golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d
+)

go.sum

@@ -0,0 +1,54 @@
+github.com/aead/siphash v1.0.1 h1:FwHfE/T45KPKYuuSAKyyvE+oPWcaQ+CUmFW0bPlM+kg=
+github.com/aead/siphash v1.0.1/go.mod h1:Nywa3cDsYNNK3gaciGTWPwHt0wlpNV15vwmswBAUSII=
+github.com/btcsuite/btcd v0.20.1-beta h1:Ik4hyJqN8Jfyv3S4AGBOmyouMsYE3EdYODkMbQjwPGw=
+github.com/btcsuite/btcd v0.20.1-beta/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
+github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f h1:bAs4lUbRJpnnkd9VhRV3jjAVU7DJVjMaK+IsvSeZvFo=
+github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
+github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d/go.mod h1:+5NJ2+qvTyV9exUAL/rxXi3DcLg2Ts+ymUAY5y4NvMg=
+github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd/go.mod h1:HHNXQzUsZCxOoE+CPiyCTO6x34Zs86zZUiwtpXoGdtg=
+github.com/btcsuite/goleveldb v0.0.0-20160330041536-7834afc9e8cd h1:qdGvebPBDuYDPGi1WCPjy1tGyMpmDK8IEapSsszn7HE=
+github.com/btcsuite/goleveldb v0.0.0-20160330041536-7834afc9e8cd/go.mod h1:F+uVaaLLH7j4eDXPRvw78tMflu7Ie2bzYOH4Y8rRKBY=
+github.com/btcsuite/snappy-go v0.0.0-20151229074030-0bdef8d06723 h1:ZA/jbKoGcVAnER6pCHPEkGdZOV7U1oLUedErBHCUMs0=
+github.com/btcsuite/snappy-go v0.0.0-20151229074030-0bdef8d06723/go.mod h1:8woku9dyThutzjeg+3xrA5iCpBRH8XEEg3lh6TiUghc=
+github.com/btcsuite/websocket v0.0.0-20150119174127-31079b680792/go.mod h1:ghJtEyQwv5/p4Mg4C0fgbePVuGr935/5ddU9Z3TmDRY=
+github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46fmI40EZs=
+github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495 h1:6IyqGr3fnd0tM3YxipK27TUskaOVUjU2nG45yzwcQKY=
+github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
+github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
+github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
+github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/jessevdk/go-flags v0.0.0-20141203071132-1679536dcc89/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
+github.com/jrick/logrotate v1.0.0/go.mod h1:LNinyqDIJnpAur+b8yyulnQw/wDuN1+BYKlTRt3OuAQ=
+github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23 h1:FOOIBWrEkLgmlgGfMuZT83xIwfPDxEI2OHu6xUmJMFE=
+github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23/go.mod h1:J+Gs4SYgM6CZQHDETBtE9HaSEkGmuNXF86RwHhHUvq4=
+github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/ginkgo v1.7.0 h1:WSHQ+IS43OoUrWtD1/bbclrwK8TTH5hzp+umCiuxHgs=
+github.com/onsi/ginkgo v1.7.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/gomega v1.4.3 h1:RE1xgDvH7imwFD45h+u2SgIfERHlS2yNG4DObb5BSKU=
+github.com/onsi/gomega v1.4.3/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1CpauHY=
+golang.org/x/crypto v0.0.0-20170930174604-9419663f5a44/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d h1:2+ZP7EfsZV7Vvmx3TIqSlSzATMkTAKqM14YGFPoSKjI=
+golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f h1:wMNYb4v58l5UBM7MYRLPG6ZhfOqbKu7X5eyFl8ZhKvA=
+golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20180909124046-d0be0721c37e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=
+gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
+gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

psbt/bip32.go

@@ -0,0 +1,77 @@
+package psbt
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// Bip32Derivation encapsulates the data for the input and output
+// Bip32Derivation key-value fields.
+//
+// TODO(roasbeef): use hdkeychain here instead?
+type Bip32Derivation struct {
+	// PubKey is the raw pubkey serialized in compressed format.
+	PubKey []byte
+
+	// MasterKeyFingerprint is the finger print of the master pubkey.
+	MasterKeyFingerprint uint32
+
+	// Bip32Path is the BIP 32 path with child index as a distinct integer.
+	Bip32Path []uint32
+}
+
+// checkValid ensures that the PubKey in the Bip32Derivation struct is valid.
+func (pb *Bip32Derivation) checkValid() bool {
+	return validatePubkey(pb.PubKey)
+}
+
+// Bip32Sorter implements sort.Interface for the Bip32Derivation struct.
+type Bip32Sorter []*Bip32Derivation
+
+func (s Bip32Sorter) Len() int { return len(s) }
+
+func (s Bip32Sorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+func (s Bip32Sorter) Less(i, j int) bool {
+	return bytes.Compare(s[i].PubKey, s[j].PubKey) < 0
+}
+
+// readBip32Derivation deserializes a byte slice containing chunks of 4 byte
+// little endian encodings of uint32 values, the first of which is the
+// masterkeyfingerprint and the remainder of which are the derivation path.
+func readBip32Derivation(path []byte) (uint32, []uint32, error) {
+
+	if len(path)%4 != 0 || len(path)/4-1 < 1 {
+		return 0, nil, ErrInvalidPsbtFormat
+	}
+
+	masterKeyInt := binary.LittleEndian.Uint32(path[:4])
+
+	var paths []uint32
+	for i := 4; i < len(path); i += 4 {
+		paths = append(paths, binary.LittleEndian.Uint32(path[i:i+4]))
+	}
+
+	return masterKeyInt, paths, nil
+}
+
+// SerializeBIP32Derivation takes a master key fingerprint as defined in BIP32,
+// along with a path specified as a list of uint32 values, and returns a
+// bytestring specifying the derivation in the format required by BIP174: //
+// master key fingerprint (4) || child index (4) || child index (4) || ....
+func SerializeBIP32Derivation(masterKeyFingerprint uint32,
+	bip32Path []uint32) []byte {
+
+	var masterKeyBytes [4]byte
+	binary.LittleEndian.PutUint32(masterKeyBytes[:], masterKeyFingerprint)
+
+	derivationPath := make([]byte, 0, 4+4*len(bip32Path))
+	derivationPath = append(derivationPath, masterKeyBytes[:]...)
+	for _, path := range bip32Path {
+		var pathbytes [4]byte
+		binary.LittleEndian.PutUint32(pathbytes[:], path)
+		derivationPath = append(derivationPath, pathbytes[:]...)
+	}
+
+	return derivationPath
+}

psbt/creator.go

@@ -4,44 +4,38 @@
 
 package psbt
 
-// The Creator has only one function:
-// takes a list of inputs and outputs and converts them to
-// the simplest Psbt, i.e. one with no data appended to inputs or outputs,
-// but only the raw unsigned transaction in the global section.
-
 import (
 	"github.com/btcsuite/btcd/wire"
 )
 
-// Creator holds a reference to a created Psbt struct.
-type Creator struct {
-	Cpsbt *Psbt
-}
-
-// CreatePsbt , on provision of an input and output 'skeleton' for
-// the transaction, returns a Creator struct.
-// Note that we require OutPoints and not TxIn structs, as we will
-// only populate the txid:n information, *not* any scriptSig/witness
-// information. The values of nLockTime, nSequence (per input) and
-// transaction version (must be 1 of 2) must be specified here. Note
-// that the default nSequence value is wire.MaxTxInSequenceNum.
-func (c *Creator) CreatePsbt(inputs []*wire.OutPoint,
-	outputs []*wire.TxOut, Version int32, nLockTime uint32,
-	nSequences []uint32) error {
-	// Create the new struct; the input and output lists will be empty,
-	// the unsignedTx object must be constructed and serialized,
-	// and that serialization should be entered as the only entry for
-	// the globalKVPairs list.
-
-	// Check the version is a valid Bitcoin tx version; the nLockTime
-	// can be any valid uint32. There must be one sequence number per
-	// input.
-	if !(Version == 1 || Version == 2) || len(nSequences) != len(inputs) {
-		return ErrInvalidPsbtFormat
+// MinTxVersion is the lowest transaction version that we'll permit.
+const MinTxVersion = 1
+
+// New on provision of an input and output 'skeleton' for the transaction, a
+// new partially populated PBST packet. The populated packet will include the
+// unsigned transaction, and the set of known inputs and outputs contained
+// within the unsigned transaction.  The values of nLockTime, nSequence (per
+// input) and transaction version (must be 1 of 2) must be specified here. Note
+// that the default nSequence value is wire.MaxTxInSequenceNum.  Referencing
+// the PSBT BIP, this function serves the roles of teh Creator.
+func New(inputs []*wire.OutPoint,
+	outputs []*wire.TxOut, version int32, nLockTime uint32,
+	nSequences []uint32) (*Packet, error) {
+
+	// Create the new struct; the input and output lists will be empty, the
+	// unsignedTx object must be constructed and serialized, and that
+	// serialization should be entered as the only entry for the
+	// globalKVPairs list.
+	//
+	// Ensure that the version of the transaction is greater then our
+	// minimum allowed transaction version. There must be one sequence
+	// number per input.
+	if version < MinTxVersion || len(nSequences) != len(inputs) {
+		return nil, ErrInvalidPsbtFormat
 	}
-	unsignedTx := wire.NewMsgTx(Version)
-	unsignedTx.LockTime = nLockTime
 
+	unsignedTx := wire.NewMsgTx(version)
+	unsignedTx.LockTime = nLockTime
 	for i, in := range inputs {
 		unsignedTx.AddTxIn(&wire.TxIn{
 			PreviousOutPoint: *in,
@@ -57,14 +51,13 @@ func (c *Creator) CreatePsbt(inputs []*wire.OutPoint,
 	// transaction; the unknown list can be nil.
 	pInputs := make([]PInput, len(unsignedTx.TxIn))
 	pOutputs := make([]POutput, len(unsignedTx.TxOut))
-	c.Cpsbt = &Psbt{
+
+	// This new Psbt is "raw" and contains no key-value fields, so sanity
+	// checking with c.Cpsbt.SanityCheck() is not required.
+	return &Packet{
 		UnsignedTx: unsignedTx,
 		Inputs:     pInputs,
 		Outputs:    pOutputs,
 		Unknowns:   nil,
-	}
-
-	// This new Psbt is "raw" and contains no key-value fields,
-	// so sanity checking with c.Cpsbt.SanityCheck() is not required.
-	return nil
+	}, nil
 }

psbt/extractor.go

@@ -12,55 +12,70 @@ package psbt
 import (
 	"bytes"
 
+	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 )
 
-// Extract takes a finalized psbt and outputs a network serialization
-func Extract(p *Psbt) ([]byte, error) {
+// Extract takes a finalized psbt.Packet and outputs a finalized transaction
+// instance. Note that if the PSBT is in-complete, then an error
+// ErrIncompletePSBT will be returned. As the extracted transaction has been
+// fully finalized, it will be ready for network broadcast once returned.
+func Extract(p *Packet) (*wire.MsgTx, error) {
+	// If the packet isn't complete, then we'll return an error as it
+	// doesn't have all the required witness data.
 	if !p.IsComplete() {
 		return nil, ErrIncompletePSBT
 	}
-	var err error
-	// We take the existing UnsignedTx field and append SignatureScript
-	// and Witness as appropriate, then allow MsgTx to do the serialization
-	// for us.
-	newTx := p.UnsignedTx.Copy()
-	for i, tin := range newTx.TxIn {
+
+	// First, we'll make a copy of the underlying unsigned transaction (the
+	// initial template) so we don't mutate it during our activates below.
+	finalTx := p.UnsignedTx.Copy()
+
+	// For each input, we'll now populate any relevant witness and
+	// sigScript data.
+	for i, tin := range finalTx.TxIn {
+		// We'll grab the corresponding internal packet input which
+		// matches this materialized transaction input and emplace that
+		// final sigScript (if present).
 		pInput := p.Inputs[i]
 		if pInput.FinalScriptSig != nil {
 			tin.SignatureScript = pInput.FinalScriptSig
 		}
+
+		// Similarly, if there's a final witness, then we'll also need
+		// to extract that as well, parsing the lower-level transaction
+		// encoding.
 		if pInput.FinalScriptWitness != nil {
-			// to set the witness, need to re-deserialize the field
-			// For each input, the witness is encoded as a stack
-			// with one or more items. Therefore, we first read a
-			// varint which encodes the number of stack items.
-			r := bytes.NewReader(pInput.FinalScriptWitness)
-			witCount, err := wire.ReadVarInt(r, 0)
+			// In order to set the witness, need to re-deserialize
+			// the field as encoded within the PSBT packet.  For
+			// each input, the witness is encoded as a stack with
+			// one or more items.
+			witnessReader := bytes.NewReader(
+				pInput.FinalScriptWitness,
+			)
+
+			// First we extract the number of witness elements
+			// encoded in the above witnessReader.
+			witCount, err := wire.ReadVarInt(witnessReader, 0)
 			if err != nil {
 				return nil, err
 			}
 
-			// Then for witCount number of stack items, each item
-			// has a varint length prefix, followed by the witness
-			// item itself.
-			tin.Witness = make([][]byte, witCount)
+			// Now that we know how may inputs we'll need, we'll
+			// construct a packing slice, then read out each input
+			// (with a varint prefix) from the witnessReader.
+			tin.Witness = make(wire.TxWitness, witCount)
 			for j := uint64(0); j < witCount; j++ {
-				// the 10000 size limit is as per BIP141 for witness script;
-				// TODO this constant should be somewhere else in the lib,
-				// perhaps btcd/wire/common.go ?
-				wit, err := wire.ReadVarBytes(r, 0, 10000, "witness")
+				wit, err := wire.ReadVarBytes(
+					witnessReader, 0, txscript.MaxScriptSize, "witness",
+				)
 				if err != nil {
 					return nil, err
 				}
 				tin.Witness[j] = wit
 			}
 		}
 	}
-	var networkSerializedTx bytes.Buffer
-	err = newTx.Serialize(&networkSerializedTx)
-	if err != nil {
-		return nil, err
-	}
-	return networkSerializedTx.Bytes(), nil
+
+	return finalTx, nil
 }