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// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <psbt.h>
#include <util/check.h>
#include <util/strencodings.h>
PartiallySignedTransaction::PartiallySignedTransaction(const CMutableTransaction& tx) : tx(tx)
{
inputs.resize(tx.vin.size());
outputs.resize(tx.vout.size());
}
bool PartiallySignedTransaction::IsNull() const
{
return !tx && inputs.empty() && outputs.empty() && unknown.empty();
}
bool PartiallySignedTransaction::Merge(const PartiallySignedTransaction& psbt)
{
// Prohibited to merge two PSBTs over different transactions
if (tx->GetHash() != psbt.tx->GetHash()) {
return false;
}
for (unsigned int i = 0; i < inputs.size(); ++i) {
inputs[i].Merge(psbt.inputs[i]);
}
for (unsigned int i = 0; i < outputs.size(); ++i) {
outputs[i].Merge(psbt.outputs[i]);
}
unknown.insert(psbt.unknown.begin(), psbt.unknown.end());
return true;
}
bool PartiallySignedTransaction::AddInput(const CTxIn& txin, PSBTInput& psbtin)
{
if (std::find(tx->vin.begin(), tx->vin.end(), txin) != tx->vin.end()) {
return false;
}
tx->vin.push_back(txin);
psbtin.partial_sigs.clear();
psbtin.final_script_sig.clear();
psbtin.final_script_witness.SetNull();
inputs.push_back(psbtin);
return true;
}
bool PartiallySignedTransaction::AddOutput(const CTxOut& txout, const PSBTOutput& psbtout)
{
tx->vout.push_back(txout);
outputs.push_back(psbtout);
return true;
}
bool PartiallySignedTransaction::GetInputUTXO(CTxOut& utxo, int input_index) const
{
PSBTInput input = inputs[input_index];
uint32_t prevout_index = tx->vin[input_index].prevout.n;
if (input.non_witness_utxo) {
if (prevout_index >= input.non_witness_utxo->vout.size()) {
return false;
}
utxo = input.non_witness_utxo->vout[prevout_index];
} else if (!input.witness_utxo.IsNull()) {
utxo = input.witness_utxo;
} else {
return false;
}
return true;
}
bool PSBTInput::IsNull() const
{
return !non_witness_utxo && witness_utxo.IsNull() && partial_sigs.empty() && unknown.empty() && hd_keypaths.empty() && redeem_script.empty() && witness_script.empty();
}
void PSBTInput::FillSignatureData(SignatureData& sigdata) const
{
if (!final_script_sig.empty()) {
sigdata.scriptSig = final_script_sig;
sigdata.complete = true;
}
if (!final_script_witness.IsNull()) {
sigdata.scriptWitness = final_script_witness;
sigdata.complete = true;
}
if (sigdata.complete) {
return;
}
sigdata.signatures.insert(partial_sigs.begin(), partial_sigs.end());
if (!redeem_script.empty()) {
sigdata.redeem_script = redeem_script;
}
if (!witness_script.empty()) {
sigdata.witness_script = witness_script;
}
for (const auto& key_pair : hd_keypaths) {
sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
}
}
void PSBTInput::FromSignatureData(const SignatureData& sigdata)
{
if (sigdata.complete) {
partial_sigs.clear();
hd_keypaths.clear();
redeem_script.clear();
witness_script.clear();
if (!sigdata.scriptSig.empty()) {
final_script_sig = sigdata.scriptSig;
}
if (!sigdata.scriptWitness.IsNull()) {
final_script_witness = sigdata.scriptWitness;
}
return;
}
partial_sigs.insert(sigdata.signatures.begin(), sigdata.signatures.end());
if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
redeem_script = sigdata.redeem_script;
}
if (witness_script.empty() && !sigdata.witness_script.empty()) {
witness_script = sigdata.witness_script;
}
for (const auto& entry : sigdata.misc_pubkeys) {
hd_keypaths.emplace(entry.second);
}
}
void PSBTInput::Merge(const PSBTInput& input)
{
if (!non_witness_utxo && input.non_witness_utxo) non_witness_utxo = input.non_witness_utxo;
if (witness_utxo.IsNull() && !input.witness_utxo.IsNull()) {
// TODO: For segwit v1, we will want to clear out the non-witness utxo when setting a witness one. For v0 and non-segwit, this is not safe
witness_utxo = input.witness_utxo;
}
partial_sigs.insert(input.partial_sigs.begin(), input.partial_sigs.end());
hd_keypaths.insert(input.hd_keypaths.begin(), input.hd_keypaths.end());
unknown.insert(input.unknown.begin(), input.unknown.end());
if (redeem_script.empty() && !input.redeem_script.empty()) redeem_script = input.redeem_script;
if (witness_script.empty() && !input.witness_script.empty()) witness_script = input.witness_script;
if (final_script_sig.empty() && !input.final_script_sig.empty()) final_script_sig = input.final_script_sig;
if (final_script_witness.IsNull() && !input.final_script_witness.IsNull()) final_script_witness = input.final_script_witness;
}
void PSBTOutput::FillSignatureData(SignatureData& sigdata) const
{
if (!redeem_script.empty()) {
sigdata.redeem_script = redeem_script;
}
if (!witness_script.empty()) {
sigdata.witness_script = witness_script;
}
for (const auto& key_pair : hd_keypaths) {
sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
}
}
void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
{
if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
redeem_script = sigdata.redeem_script;
}
if (witness_script.empty() && !sigdata.witness_script.empty()) {
witness_script = sigdata.witness_script;
}
for (const auto& entry : sigdata.misc_pubkeys) {
hd_keypaths.emplace(entry.second);
}
}
bool PSBTOutput::IsNull() const
{
return redeem_script.empty() && witness_script.empty() && hd_keypaths.empty() && unknown.empty();
}
void PSBTOutput::Merge(const PSBTOutput& output)
{
hd_keypaths.insert(output.hd_keypaths.begin(), output.hd_keypaths.end());
unknown.insert(output.unknown.begin(), output.unknown.end());
if (redeem_script.empty() && !output.redeem_script.empty()) redeem_script = output.redeem_script;
if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
}
bool PSBTInputSigned(const PSBTInput& input)
{
return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
}
size_t CountPSBTUnsignedInputs(const PartiallySignedTransaction& psbt) {
size_t count = 0;
for (const auto& input : psbt.inputs) {
if (!PSBTInputSigned(input)) {
count++;
}
}
return count;
}
void UpdatePSBTOutput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index)
{
CMutableTransaction& tx = *Assert(psbt.tx);
const CTxOut& out = tx.vout.at(index);
PSBTOutput& psbt_out = psbt.outputs.at(index);
// Fill a SignatureData with output info
SignatureData sigdata;
psbt_out.FillSignatureData(sigdata);
// Construct a would-be spend of this output, to update sigdata with.
// Note that ProduceSignature is used to fill in metadata (not actual signatures),
// so provider does not need to provide any private keys (it can be a HidingSigningProvider).
MutableTransactionSignatureCreator creator(&tx, /* index */ 0, out.nValue, SIGHASH_ALL);
ProduceSignature(provider, creator, out.scriptPubKey, sigdata);
// Put redeem_script, witness_script, key paths, into PSBTOutput.
psbt_out.FromSignatureData(sigdata);
}
PrecomputedTransactionData PrecomputePSBTData(const PartiallySignedTransaction& psbt)
{
const CMutableTransaction& tx = *psbt.tx;
bool have_all_spent_outputs = true;
std::vector<CTxOut> utxos(tx.vin.size());
for (size_t idx = 0; idx < tx.vin.size(); ++idx) {
if (!psbt.GetInputUTXO(utxos[idx], idx)) have_all_spent_outputs = false;
}
PrecomputedTransactionData txdata;
if (have_all_spent_outputs) {
txdata.Init(tx, std::move(utxos), true);
} else {
txdata.Init(tx, {}, true);
}
return txdata;
}
bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, const PrecomputedTransactionData* txdata, int sighash, SignatureData* out_sigdata)
{
PSBTInput& input = psbt.inputs.at(index);
const CMutableTransaction& tx = *psbt.tx;
if (PSBTInputSigned(input)) {
return true;
}
// Fill SignatureData with input info
SignatureData sigdata;
input.FillSignatureData(sigdata);
// Get UTXO
bool require_witness_sig = false;
CTxOut utxo;
if (input.non_witness_utxo) {
// If we're taking our information from a non-witness UTXO, verify that it matches the prevout.
COutPoint prevout = tx.vin[index].prevout;
if (prevout.n >= input.non_witness_utxo->vout.size()) {
return false;
}
if (input.non_witness_utxo->GetHash() != prevout.hash) {
return false;
}
utxo = input.non_witness_utxo->vout[prevout.n];
} else if (!input.witness_utxo.IsNull()) {
utxo = input.witness_utxo;
// When we're taking our information from a witness UTXO, we can't verify it is actually data from
// the output being spent. This is safe in case a witness signature is produced (which includes this
// information directly in the hash), but not for non-witness signatures. Remember that we require
// a witness signature in this situation.
require_witness_sig = true;
} else {
return false;
}
sigdata.witness = false;
bool sig_complete;
if (txdata == nullptr) {
sig_complete = ProduceSignature(provider, DUMMY_SIGNATURE_CREATOR, utxo.scriptPubKey, sigdata);
} else {
MutableTransactionSignatureCreator creator(&tx, index, utxo.nValue, txdata, sighash);
sig_complete = ProduceSignature(provider, creator, utxo.scriptPubKey, sigdata);
}
// Verify that a witness signature was produced in case one was required.
if (require_witness_sig && !sigdata.witness) return false;
input.FromSignatureData(sigdata);
// If we have a witness signature, put a witness UTXO.
// TODO: For segwit v1, we should remove the non_witness_utxo
if (sigdata.witness) {
input.witness_utxo = utxo;
// input.non_witness_utxo = nullptr;
}
// Fill in the missing info
if (out_sigdata) {
out_sigdata->missing_pubkeys = sigdata.missing_pubkeys;
out_sigdata->missing_sigs = sigdata.missing_sigs;
out_sigdata->missing_redeem_script = sigdata.missing_redeem_script;
out_sigdata->missing_witness_script = sigdata.missing_witness_script;
}
return sig_complete;
}
bool FinalizePSBT(PartiallySignedTransaction& psbtx)
{
// Finalize input signatures -- in case we have partial signatures that add up to a complete
// signature, but have not combined them yet (e.g. because the combiner that created this
// PartiallySignedTransaction did not understand them), this will combine them into a final
// script.
bool complete = true;
const PrecomputedTransactionData txdata = PrecomputePSBTData(psbtx);
for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
complete &= SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, &txdata, SIGHASH_ALL);
}
return complete;
}
bool FinalizeAndExtractPSBT(PartiallySignedTransaction& psbtx, CMutableTransaction& result)
{
// It's not safe to extract a PSBT that isn't finalized, and there's no easy way to check
// whether a PSBT is finalized without finalizing it, so we just do this.
if (!FinalizePSBT(psbtx)) {
return false;
}
result = *psbtx.tx;
for (unsigned int i = 0; i < result.vin.size(); ++i) {
result.vin[i].scriptSig = psbtx.inputs[i].final_script_sig;
result.vin[i].scriptWitness = psbtx.inputs[i].final_script_witness;
}
return true;
}
TransactionError CombinePSBTs(PartiallySignedTransaction& out, const std::vector<PartiallySignedTransaction>& psbtxs)
{
out = psbtxs[0]; // Copy the first one
// Merge
for (auto it = std::next(psbtxs.begin()); it != psbtxs.end(); ++it) {
if (!out.Merge(*it)) {
return TransactionError::PSBT_MISMATCH;
}
}
return TransactionError::OK;
}
std::string PSBTRoleName(PSBTRole role) {
switch (role) {
case PSBTRole::CREATOR: return "creator";
case PSBTRole::UPDATER: return "updater";
case PSBTRole::SIGNER: return "signer";
case PSBTRole::FINALIZER: return "finalizer";
case PSBTRole::EXTRACTOR: return "extractor";
// no default case, so the compiler can warn about missing cases
}
assert(false);
}
bool DecodeBase64PSBT(PartiallySignedTransaction& psbt, const std::string& base64_tx, std::string& error)
{
bool invalid;
std::string tx_data = DecodeBase64(base64_tx, &invalid);
if (invalid) {
error = "invalid base64";
return false;
}
return DecodeRawPSBT(psbt, tx_data, error);
}
bool DecodeRawPSBT(PartiallySignedTransaction& psbt, const std::string& tx_data, std::string& error)
{
CDataStream ss_data(MakeUCharSpan(tx_data), SER_NETWORK, PROTOCOL_VERSION);
try {
ss_data >> psbt;
if (!ss_data.empty()) {
error = "extra data after PSBT";
return false;
}
} catch (const std::exception& e) {
error = e.what();
return false;
}
return true;
}
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