psbt: create new enum type for return values of Sign method
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Olaoluwa Osuntokun
parent
3385fba2f2
commit
e2fd54d981
1 changed files with 81 additions and 61 deletions
142
psbt/signer.go
142
psbt/signer.go
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@ -4,129 +4,149 @@
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package psbt
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// signer encapsulates the role 'Signer'
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// as specified in BIP174; it controls the insertion of signatures;
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// the Sign() function will attempt to insert signatures using
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// Updater.addPartialSignature, after first ensuring the Psbt is in the
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// correct state.
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// signer encapsulates the role 'Signer' as specified in BIP174; it controls
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// the insertion of signatures; the Sign() function will attempt to insert
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// signatures using Updater.addPartialSignature, after first ensuring the Psbt
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// is in the correct state.
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import (
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"github.com/btcsuite/btcd/txscript"
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)
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// SignOutcome is a enum-like value that expresses the outcome of a call to the
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// Sign method.
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type SignOutcome int
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const (
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// SignSuccesful indicates that the partial signature was successfully
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// attached.
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SignSuccesful = 0
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// SignFinalized indicates that this input is already finalized, so the provided
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// signature was *not* attached
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SignFinalized = 1
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// SignInvalid indicates that the provided signature data was not valid. In this case
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// an error will also be returned.
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SignInvalid = -1
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)
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// Sign allows the caller to sign a PSBT at a particular input; they
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// must provide a signature and a pubkey, both as byte slices; they can also
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// optionally provide both witnessScript and/or redeemScript, otherwise
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// these arguments must be set as nil (and in that case, they must already
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// be present in the PSBT if required for signing to succeed).
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// optionally provide both witnessScript and/or redeemScript, otherwise these
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// arguments must be set as nil (and in that case, they must already be present
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// in the PSBT if required for signing to succeed).
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//
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// Return value:
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// 0 indicates that the partial signature was successfully attached.
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// 1 indicates that this input is already finalized, so the provided
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// signature was *not* attached
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// -1 indicates that the provided signature data was not valid. In this
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// case an error will also be returned.
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//
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// This serves as a wrapper around Updater.addPartialSignature;
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// it ensures that the redeemScript and witnessScript are updated as needed
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// (note that the Updater is allowed to add redeemScripts and witnessScripts
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// independently, before signing), and ensures that the right form of utxo
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// field (NonWitnessUtxo or WitnessUtxo) is included in the input so that
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// signature insertion (and then finalization) can take place.
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// This serves as a wrapper around Updater.addPartialSignature; it ensures that
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// the redeemScript and witnessScript are updated as needed (note that the
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// Updater is allowed to add redeemScripts and witnessScripts independently,
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// before signing), and ensures that the right form of utxo field
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// (NonWitnessUtxo or WitnessUtxo) is included in the input so that signature
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// insertion (and then finalization) can take place.
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func (u *Updater) Sign(inIndex int, sig []byte, pubKey []byte,
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redeemScript []byte, witnessScript []byte) (int, error) {
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redeemScript []byte, witnessScript []byte) (SignOutcome, error) {
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if isFinalized(u.Upsbt, inIndex) {
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return 1, nil
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return SignFinalized, nil
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}
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// Add the witnessScript to the PSBT in preparation. If it already
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// exists, it will be overwritten.
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if witnessScript != nil {
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// Add the witnessScript to the PSBT in preparation.
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// If it already exists, it will be overwritten.
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err := u.AddInWitnessScript(witnessScript, inIndex)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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// Add the redeemScript to the PSBT in preparation. If it already
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// exists, it will be overwritten.
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if redeemScript != nil {
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// Add the redeemScript to the PSBT in preparation.
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// If it already exists, it will be overwritten.
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err := u.AddInRedeemScript(redeemScript, inIndex)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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// At this point, the PSBT must have the requisite
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// witnessScript or redeemScript fields for signing to succeed.
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// case 1: if witnessScript is present, it must be of type witness;
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// At this point, the PSBT must have the requisite witnessScript or
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// redeemScript fields for signing to succeed.
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//
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// Case 1: if witnessScript is present, it must be of type witness;
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// if not, signature insertion will of course fail.
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if u.Upsbt.Inputs[inIndex].WitnessScript != nil {
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switch {
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case u.Upsbt.Inputs[inIndex].WitnessScript != nil:
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if u.Upsbt.Inputs[inIndex].WitnessUtxo == nil {
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err := nonWitnessToWitness(u.Upsbt, inIndex)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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err := u.addPartialSignature(inIndex, sig, pubKey)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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} else if u.Upsbt.Inputs[inIndex].RedeemScript != nil {
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// case 2: no witness script, only redeem script; can be legacy
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// p2sh or p2sh-wrapped p2wkh
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// Case 2: no witness script, only redeem script; can be legacy p2sh or
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// p2sh-wrapped p2wkh.
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case u.Upsbt.Inputs[inIndex].RedeemScript != nil:
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// We only need to decide if the input is witness, and we don't
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// rely on the witnessutxo/nonwitnessutxo in the PSBT, instead
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// we check the redeemScript content:
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// we check the redeemScript content.
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if txscript.IsWitnessProgram(redeemScript) {
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if u.Upsbt.Inputs[inIndex].WitnessUtxo == nil {
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err := nonWitnessToWitness(u.Upsbt, inIndex)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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}
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// If it is not a valid witness program, we here assume
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// that the provided WitnessUtxo/NonWitnessUtxo field was correct.
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// If it is not a valid witness program, we here assume that
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// the provided WitnessUtxo/NonWitnessUtxo field was correct.
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err := u.addPartialSignature(inIndex, sig, pubKey)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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} else {
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// case 3: Neither provided only works for native p2wkh, or
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// non-segwit non-p2sh. To check if it's segwit, check
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// the scriptPubKey of the output.
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// Case 3: Neither provided only works for native p2wkh, or non-segwit
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// non-p2sh. To check if it's segwit, check the scriptPubKey of the
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// output.
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default:
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if u.Upsbt.Inputs[inIndex].WitnessUtxo == nil {
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outIndex := u.Upsbt.UnsignedTx.TxIn[inIndex].
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PreviousOutPoint.Index
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script := u.Upsbt.Inputs[inIndex].NonWitnessUtxo.
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TxOut[outIndex].PkScript
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outIndex := u.Upsbt.UnsignedTx.TxIn[inIndex].PreviousOutPoint.Index
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script := u.Upsbt.Inputs[inIndex].NonWitnessUtxo.TxOut[outIndex].PkScript
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if txscript.IsWitnessProgram(script) {
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err := nonWitnessToWitness(u.Upsbt, inIndex)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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}
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err := u.addPartialSignature(inIndex, sig, pubKey)
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if err != nil {
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return -1, err
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return SignInvalid, err
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}
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}
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return 0, nil
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return SignSuccesful, nil
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}
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// nonWitnessToWitness extracts the TxOut from the existing
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// NonWitnessUtxo field in the given PSBT input and sets it as type
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// witness by replacing the NonWitnessUtxo field with a WitnessUtxo
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// field. See https://github.com/bitcoin/bitcoin/pull/14197
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func nonWitnessToWitness(p *Psbt, inIndex int) error {
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// nonWitnessToWitness extracts the TxOut from the existing NonWitnessUtxo
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// field in the given PSBT input and sets it as type witness by replacing the
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// NonWitnessUtxo field with a WitnessUtxo field. See
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// https://github.com/bitcoin/bitcoin/pull/14197.
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func nonWitnessToWitness(p *Packet, inIndex int) error {
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outIndex := p.UnsignedTx.TxIn[inIndex].PreviousOutPoint.Index
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txout := p.Inputs[inIndex].NonWitnessUtxo.TxOut[outIndex]
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// Remove the non-witness first, else sanity check will not pass:
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p.Inputs[inIndex].NonWitnessUtxo = nil
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u := Updater{Upsbt: p}
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u := Updater{
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Upsbt: p,
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}
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return u.AddInWitnessUtxo(txout, inIndex)
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}
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