btcutil/psbt: export helper functions, fix/add encoding of unknown fields

btcutil/psbt/bip32.go

@@ -13,7 +13,7 @@ type Bip32Derivation struct {
 	// PubKey is the raw pubkey serialized in compressed format.
 	PubKey []byte
 
-	// MasterKeyFingerprint is the finger print of the master pubkey.
+	// MasterKeyFingerprint is the fingerprint of the master pubkey.
 	MasterKeyFingerprint uint32
 
 	// Bip32Path is the BIP 32 path with child index as a distinct integer.
@@ -36,10 +36,10 @@ 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
+// 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) {
+func ReadBip32Derivation(path []byte) (uint32, []uint32, error) {
 	// BIP-0174 defines the derivation path being encoded as
 	//   "<32-bit uint> <32-bit uint>*"
 	// with the asterisk meaning 0 to n times. Which in turn means that an

btcutil/psbt/extractor.go

@@ -61,13 +61,14 @@ func Extract(p *Packet) (*wire.MsgTx, error) {
 				return nil, err
 			}
 
-			// Now that we know how may inputs we'll need, we'll
+			// Now that we know how many 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++ {
 				wit, err := wire.ReadVarBytes(
-					witnessReader, 0, txscript.MaxScriptSize, "witness",
+					witnessReader, 0,
+					txscript.MaxScriptSize, "witness",
 				)
 				if err != nil {
 					return nil, err

btcutil/psbt/finalizer.go

@@ -14,6 +14,7 @@ package psbt
 import (
 	"bytes"
 	"fmt"
+
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 )
@@ -462,7 +463,9 @@ func finalizeWitnessInput(p *Packet, inIndex int) error {
 				return ErrNotFinalizable
 			}
 
-			serializedWitness, err = writePKHWitness(sigs[0], pubKeys[0])
+			serializedWitness, err = writePKHWitness(
+				sigs[0], pubKeys[0],
+			)
 			if err != nil {
 				return err
 			}