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thehub/libs/utils/TransactionBuilder.cpp

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C++

/*
* This file is part of the Flowee project
* Copyright (C) 2019-2024 Tom Zander <tom@flowee.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "TransactionBuilder.h"
#include <hash.h>
#include <primitives/PublicKey.h>
#include <primitives/transaction.h>
#include <streaming/StreamingUtils.h>
static constexpr size_t MaxCashTokenCommitmentSize = 128;
class TransactionBuilderPrivate
{
public:
void checkCurInput()
{
assert(0 <= curInput);
assert(transaction.vin.size() > size_t(curInput));
if (0 > curInput || transaction.vin.size() <= size_t(curInput))
throw std::runtime_error("current input out of range");
}
void checkCurOutput()
{
assert(curOutput >= 0);
assert(size_t(curOutput) < transaction.vout.size());
}
CMutableTransaction transaction;
TransactionBuilder::LockingOptions defaultLocking = TransactionBuilder::NoLocking;
int curInput = -1, curOutput = -1;
struct SignInfo {
uint8_t hashType = 0;
int64_t value = 0;
PrivateKey privKey;
CScript prevOutScript;
TransactionBuilder::SignatureType signatureType = TransactionBuilder::Schnorr;
};
std::vector<SignInfo> signInfo;
struct CashToken {
int outputIndex = -1;
uint8_t bitfield = 0;
uint256 category;
uint64_t amount = 0;
std::vector<uint8_t> commitment;
};
std::vector<CashToken> cashTokens;
bool getToken(int outputIndex, CashToken **token, bool autocreate = true) {
for (size_t i = 0; i < cashTokens.size(); ++i) {
if (cashTokens.at(i).outputIndex == outputIndex) {
*token = &cashTokens[i];
return true;
}
}
if (!autocreate)
return false;
cashTokens.resize(cashTokens.size() + 1);
*token = &cashTokens.back();
assert(*token);
(*token)->outputIndex = outputIndex;
return true;
}
bool anonimize = false;
int feePerKByte = 1000;
int outputToTakeFeeFrom = -1;
};
namespace {
// helper struct to sort index-of-inputs
struct InputSorter {
const CMutableTransaction &tx;
explicit InputSorter(const CMutableTransaction &transaction) : tx(transaction) {}
bool operator()(int a, int b) const {
assert(a >= 0);
assert(b >= 0);
assert((int)tx.vin.size() > a);
assert((int)tx.vin.size() > b);
const COutPoint &poa = tx.vin.at(a).prevout;
const COutPoint &pob = tx.vin.at(b).prevout;
auto rc = poa.hash.Compare(pob.hash);
if (rc < 0)
return true;
if (rc > 0)
return false;
// equal, check output-index
return poa.n < pob.n;
}
};
// helper struct to sort index-of-outputs
struct OutputSorter {
const CMutableTransaction &tx;
explicit OutputSorter(const CMutableTransaction &transaction) : tx(transaction) {}
bool operator()(int a, int b) const {
assert(a >= 0);
assert(b >= 0);
assert((int)tx.vout.size() > a);
assert((int)tx.vout.size() > b);
const CTxOut &oa = tx.vout.at(a);
const CTxOut &ob = tx.vout.at(b);
if (oa.nValue < ob.nValue)
return true;
if (oa.nValue > ob.nValue)
return false;
return oa.scriptPubKey < ob.scriptPubKey;
}
};
// if anonimize is true, this will apply
// BIP69 sorting that aims to anonimize the transaction.
// any sorting of inputs is also applied to the signInfo vector.
CMutableTransaction sortTransaction(const CMutableTransaction &tx, std::vector<TransactionBuilderPrivate::SignInfo> &signInfo, std::vector<int> &outSortMap)
{
assert(tx.vin.size() == signInfo.size());
// First check if the transaction is eligable for sorting.
for (size_t i = 0; i < tx.vin.size(); ++i) {
// the 0x40 is the replay protection between BTC and BCH
// then we also allow SignAllOuputs and SignNoOutputs
constexpr uint8_t BadMask = 0xBC; // inverted of the allowed
const auto &si = signInfo.at(i);
uint8_t hashType = si.hashType;
if (si.prevOutScript.empty()) {
// we won't sign this, use the hashtype already on the Tx.
const auto &script = tx.vin.at(i).scriptSig;
if (script.empty()) // no signature, no problem
continue;
auto scriptIter = script.begin();
opcodetype type;
std::vector<unsigned char> p2pkhSignature;
script.GetOp(scriptIter, type, p2pkhSignature);
// for the type we only allow PUSHDATA2 or a push by-size (i.e a byte less than PUSHDATA1)
if (type == OP_PUSHDATA1
|| type <= 0
|| type > OP_PUSHDATA2
|| p2pkhSignature.size() < 65) // custom unlock script.
return tx; // we wont't sort that, it will likely break the signature.
hashType = p2pkhSignature.back();
}
if ((hashType & BadMask) != 0) // can't sort this one.
return tx;
}
// ok, lets make a sorted copy!
const std::vector<TransactionBuilderPrivate::SignInfo> origSignInfo(signInfo);
// first inputs. We sort a vector of ints based on the content (using InputSorter)
// and then copy based on that.
std::vector<int> inputs;
inputs.reserve(tx.vin.size());
for (size_t i = 0; i < tx.vin.size(); ++i) inputs.push_back(static_cast<int>(i));
InputSorter inputSorter(tx);
std::sort(inputs.begin(), inputs.end(), inputSorter);
CMutableTransaction out;
out.vin.resize(inputs.size());
for (size_t i = 0; i < inputs.size(); ++i) {
const size_t sorted = static_cast<size_t>(inputs[i]);
out.vin[i] = tx.vin.at(sorted);
signInfo[i] = origSignInfo.at(sorted);
}
// Same again, but now for outputs.
outSortMap.resize(0);
outSortMap.reserve(tx.vout.size());
for (size_t i = 0; i < tx.vout.size(); ++i) outSortMap.push_back(static_cast<int>(i));
OutputSorter outputSorter(tx);
std::sort(outSortMap.begin(), outSortMap.end(), outputSorter);
out.vout.resize(outSortMap.size());
for (size_t i = 0; i < outSortMap.size(); ++i) {
const size_t sorted = static_cast<size_t>(outSortMap[i]);
out.vout[i] = tx.vout.at(sorted);
}
return out;
}
}
TransactionBuilder::TransactionBuilder()
: d(new TransactionBuilderPrivate())
{
}
TransactionBuilder::TransactionBuilder(const Tx &existingTx)
: d(new TransactionBuilderPrivate())
{
d->transaction = CTransaction(existingTx.createOldTransaction());
d->signInfo.resize(d->transaction.vin.size());
}
TransactionBuilder::TransactionBuilder(const CTransaction &existingTx)
: d(new TransactionBuilderPrivate())
{
d->transaction = existingTx;
d->signInfo.resize(d->transaction.vin.size());
}
TransactionBuilder::~TransactionBuilder()
{
delete d;
}
void TransactionBuilder::setFeeTarget(int satsPerKByte)
{
d->feePerKByte = satsPerKByte;
}
int TransactionBuilder::appendInput(const uint256 &txid, int outputIndex)
{
const size_t pos = d->transaction.vin.size();
if (pos > 1000) // kind of random large number
throw std::runtime_error("Too many inputs");
d->transaction.vin.resize(pos + 1);
d->signInfo.resize(pos + 1);
CTxIn &in = d->transaction.vin[pos];
in.prevout.hash = txid;
in.prevout.n = outputIndex;
switch (d->defaultLocking) {
case TransactionBuilder::LockMiningOnTime:
case TransactionBuilder::LockMiningOnBlock:
in.nSequence = in.SEQUENCE_LOCKTIME_DISABLE_FLAG;
break;
default: // default of the instance is fine
break;
}
d->curInput = static_cast<int>(pos);
return d->curInput;
}
int TransactionBuilder::selectInput(int index)
{
assert(index >= 0);
if (index < 0) throw std::runtime_error("Index is a natural number");
d->curInput = std::min(static_cast<int>(d->transaction.vin.size()) -1, index);
return d->curInput;
}
int TransactionBuilder::outputCount() const
{
return static_cast<int>(d->transaction.vout.size());
}
int TransactionBuilder::inputCount() const
{
return static_cast<int>(d->transaction.vin.size());
}
void TransactionBuilder::pushInputSignature(const PrivateKey &privKey, const CScript &prevOutScript, int64_t value, SignatureType type, SignInputs inputs, SignOutputs outputs)
{
d->checkCurInput();
TransactionBuilderPrivate::SignInfo &si = d->signInfo[d->curInput];
si.hashType = inputs == SignOnlyThisInput ? 0xC0 : 0x40;
switch (outputs) {
case SignAllOuputs: si.hashType += 1; break;
case SignNoOutputs: si.hashType += 2; break;
case SignSingleOutput: si.hashType += 3; break;
}
si.privKey = privKey;
si.prevOutScript = prevOutScript;
si.value = value;
si.signatureType = type;
}
void TransactionBuilder::deleteInput(int index)
{
assert(index >= 0);
assert(size_t(index) < d->transaction.vin.size());
assert(size_t(index) < d->signInfo.size());
auto iter = d->transaction.vin.begin();
iter += index;
d->transaction.vin.erase(iter);
auto iter2 = d->signInfo.begin();
iter2 += index;
d->signInfo.erase(iter2);
selectInput(index);
}
int TransactionBuilder::appendOutput(int64_t value)
{
const size_t pos = d->transaction.vout.size();
if (pos > 1000) // kind of random large number
throw std::runtime_error("Too many outputs");
d->transaction.vout.resize(pos + 1);
CTxOut &out = d->transaction.vout[pos];
out.nValue = value;
d->curOutput = static_cast<int>(pos);
return d->curOutput;
}
int TransactionBuilder::selectOutput(int index)
{
assert(index >= 0);
if (index < 0) throw std::runtime_error("Index is a natural number");
d->curOutput = std::min(static_cast<int>(d->transaction.vout.size()) -1, index);
return d->curOutput;
}
void TransactionBuilder::setOutputValue(int64_t value)
{
assert(value >= 0);
assert(d->curOutput >= 0);
assert(int(d->transaction.vout.size()) > d->curOutput);
d->transaction.vout[d->curOutput].nValue = value;
}
void TransactionBuilder::setOutputFeeSource(int outputIndex)
{
if (outputIndex == -1)
outputIndex = d->curOutput;
d->outputToTakeFeeFrom = outputIndex;
}
void TransactionBuilder::pushOutputPay2Address(const KeyId &address)
{
d->checkCurOutput();
CScript outScript;
outScript << OP_DUP << OP_HASH160;
std::vector<unsigned char> data(address.begin(), address.end());
outScript << data;
outScript << OP_EQUALVERIFY << OP_CHECKSIG;
pushOutputScript(outScript);
}
void TransactionBuilder::pushOutputScript(const CScript &script)
{
assert(d->curOutput >= 0);
assert(static_cast<size_t>(d->curOutput) < d->transaction.vout.size());
d->transaction.vout[static_cast<size_t>(d->curOutput)].scriptPubKey = script;
}
void TransactionBuilder::pushOutputPay2Script(const std::vector<uint8_t> &p2SHash)
{
d->checkCurOutput();
CScript outScript;
if (p2SHash.size() == 20)
outScript << OP_HASH160;
else if (p2SHash.size() == 32)
outScript << OP_HASH256;
outScript << p2SHash;
outScript << OP_EQUAL;
pushOutputScript(outScript);
}
void TransactionBuilder::pushOutputNullData(const std::vector<uint8_t> &data)
{
assert(d->curOutput >= 0);
assert(static_cast<size_t>(d->curOutput) < d->transaction.vout.size());
CScript script;
script << OP_RETURN << data;
d->transaction.vout[static_cast<size_t>(d->curOutput)].scriptPubKey = script;
}
void TransactionBuilder::deleteOutput(int index)
{
assert(index >= 0);
if (size_t(index) >= d->transaction.vout.size())
throw std::runtime_error("Out of bounds");
auto iter = d->transaction.vout.begin();
iter += index;
d->transaction.vout.erase(iter);
// adjust indexes on cashTokens
for (auto iter = d->cashTokens.begin(); iter != d->cashTokens.end(); ++iter) {
if (iter->outputIndex == index)
d->cashTokens.erase(iter);
else if (iter->outputIndex > index)
--iter->outputIndex;
}
if (d->outputToTakeFeeFrom >= index)
--d->outputToTakeFeeFrom;
selectOutput(index);
}
void TransactionBuilder::startOutputToken(const uint256 &category, uint8_t bitfield)
{
assert(d->curOutput >= 0);
TransactionBuilderPrivate::CashToken *ct = nullptr;
d->getToken(d->curOutput, &ct);
assert(ct);
ct->category = category;
ct->bitfield = bitfield;
}
void TransactionBuilder::pushNftCommitment(const std::vector<uint8_t> &data)
{
assert(d->curOutput >= 0);
if (data.size() > MaxCashTokenCommitmentSize)
throw std::runtime_error("Illegal commitment size");
TransactionBuilderPrivate::CashToken *ct = nullptr;
if (!d->getToken(d->curOutput, &ct, false))
throw std::runtime_error("Builder: token not started");
assert(ct);
if ((ct->bitfield & Tx::HasCommitment) == 0)
throw std::runtime_error("push: Token has no commitment");
ct->commitment = data;
}
void TransactionBuilder::pushOutputFtAmount(uint64_t amount)
{
assert(d->curOutput >= 0);
TransactionBuilderPrivate::CashToken *ct = nullptr;
if (!d->getToken(d->curOutput, &ct, false))
throw std::runtime_error("Builder: token not started");
assert(ct);
if ((ct->bitfield & Tx::HasFtAmount) == 0)
throw std::runtime_error("push: Token has no FT");
ct->amount = amount;
}
void TransactionBuilder::clearOutputToken()
{
for (auto iter = d->cashTokens.begin(); iter != d->cashTokens.end(); ++iter) {
if (iter->outputIndex == d->curOutput) {
d->cashTokens.erase(iter);
return;
}
}
}
Tx TransactionBuilder::createTransaction(const std::shared_ptr<Streaming::BufferPool> &pool) const
{
CMutableTransaction tx = d->transaction;
std::vector<TransactionBuilderPrivate::SignInfo> signInfo(d->signInfo);
std::vector<int> outSortMap;
if (d->anonimize) {
// sort the transaction prior to signing inputs.
tx = sortTransaction(d->transaction, signInfo, outSortMap);
assert(signInfo.size() == d->signInfo.size());
}
// add cashtokens to outputs
for (const auto &ct : d->cashTokens) {
assert(ct.outputIndex >= 0);
size_t outputIndex = ct.outputIndex;
if (d->anonimize) {
assert(outputIndex < outSortMap.size());
outputIndex = outSortMap.at(outputIndex);
}
assert(tx.vout.size() > outputIndex);
auto base = tx.vout[outputIndex].scriptPubKey;
std::vector<uint8_t> output;
output.reserve(32 + MaxCashTokenCommitmentSize + 10 + base.size());
output.resize(34);
output[0] = 0xef; // magic indicator
memcpy(&output[1], ct.category.begin(), 32);
output[33] = ct.bitfield;
if (ct.bitfield & Tx::HasCommitment) {
assert(ct.commitment.size() <= MaxCashTokenCommitmentSize);
if (ct.commitment.size() == 0)
throw std::runtime_error("Token commitment missing");
const size_t i = output.size();
output.resize(i + ct.commitment.size() + 1);
output[i] = (uint8_t) ct.commitment.size();
memcpy(&output[i + 1], &ct.commitment[0], ct.commitment.size());
}
if (ct.bitfield & Tx::HasFtAmount) {
if (ct.amount == 0 || ct.amount > 0xffffffffffffff7f)
throw std::runtime_error("Token Ft-amount wrong");
const size_t i = output.size();
output.resize(output.size() + 9);
auto bytes = Streaming::writeCompactSize(reinterpret_cast<char*>(&output[i]), ct.amount);
output.resize(i + bytes);
}
const size_t i = output.size();
output.resize(output.size() + base.size());
memcpy(&output[i], &base[0], base.size());
tx.vout[outputIndex].scriptPubKey = CScript(output.begin(), output.end());
}
/* sign and do fee
*
* The fee is set based on the size of the transaction. The main way to change the size is with a different
* signature. Signatures change based on the fee if that comes from an existing output. So, this requires
* iteration and at least 2 passes to make work.
*/
while (true) {
// Sign all inputs we can.
bool haveAllInputAmounts = true;
int64_t totalInputs = 0;
assert(tx.vin.size() == signInfo.size());
for (size_t i = 0; i < tx.vin.size(); ++i) {
const TransactionBuilderPrivate::SignInfo &si = signInfo[i];
if (si.prevOutScript.empty()) {
haveAllInputAmounts = false;
continue;
}
totalInputs += si.value;
uint256 hashPrevouts;
if (!(si.hashType & SignOnlyThisInput)) {
CHashWriter ss(SER_GETHASH, 0);
for (size_t n = 0; n < tx.vin.size(); ++n) {
ss << tx.vin[n].prevout;
}
hashPrevouts = ss.finalizeHash();
}
uint256 hashSequence;
if (!(si.hashType & SignOnlyThisInput) && (si.hashType & 0x1f) != SignSingleOutput
&& (si.hashType & 0x1f) != SignNoOutputs) {
CHashWriter ss(SER_GETHASH, 0);
for (size_t n = 0; n < tx.vin.size(); ++n) {
ss << tx.vin[n].nSequence;
}
hashSequence = ss.finalizeHash();
}
uint256 hashOutputs;
if ((si.hashType & 0x1f) != SignSingleOutput && (si.hashType & 0x1f) != SignNoOutputs) {
CHashWriter ss(SER_GETHASH, 0);
for (size_t n = 0; n < tx.vout.size(); ++n) {
ss << tx.vout[n];
}
hashOutputs = ss.finalizeHash();
} else if ((si.hashType & 0x1f) == SignSingleOutput && i < tx.vout.size()) {
CHashWriter ss(SER_GETHASH, 0);
ss << tx.vout[i];
hashOutputs = ss.finalizeHash();
}
// use FORKID based creation of the hash we will sign.
CHashWriter ss(SER_GETHASH, 0);
ss << tx.nVersion << hashPrevouts << hashSequence;
ss << tx.vin[i].prevout;
ss << static_cast<const CScriptBase &>(si.prevOutScript);
ss << si.value << tx.vin[i].nSequence << hashOutputs;
ss << tx.nLockTime << (int) si.hashType;
const uint256 hash = ss.finalizeHash();
// the rest assumes P2PKH for now.
std::vector<unsigned char> vchSig;
if (si.signatureType == ECDSA)
si.privKey.signECDSA(hash, vchSig);
else
si.privKey.signSchnorr(hash, vchSig);
vchSig.push_back((uint8_t) si.hashType);
tx.vin[i].scriptSig = CScript();
tx.vin[i].scriptSig << vchSig;
tx.vin[i].scriptSig << ToByteVector(si.privKey.getPubKey());
}
// now lets see if fee adjustment is needed (and wanted)
if (!(d->feePerKByte > 0 && d->outputToTakeFeeFrom >= 0 && d->outputToTakeFeeFrom < (int)tx.vout.size() && haveAllInputAmounts)) {
// ok, no, we won't be updating fee.
break;
}
// We'll adjust the output amount of one output in order to reach the expected number of sats per kbyte.
int outputToUse = d->outputToTakeFeeFrom;
if (d->anonimize) {
assert(outputToUse < (int) outSortMap.size());
outputToUse = outSortMap.at(outputToUse);
}
int assignedFee = totalInputs;
for (const auto &out : tx.vout) {
assignedFee -= out.nValue;
}
// a positive diff means we underpaid fee
const int diff = static_cast<int64_t>(tx.GetSerializeSize(1, 1)) * d->feePerKByte / 1000 - assignedFee;
if (diff <= 0)
break; // done
tx.vout[outputToUse].nValue -= diff;
// We're inside of a while-true, so lets re-calc the signatures!
}
return Tx::fromOldTransaction(tx, pool);
}
bool TransactionBuilder::anonimize() const
{
return d->anonimize;
}
void TransactionBuilder::setAnonimize(bool on)
{
d->anonimize = on;
}
void TransactionBuilder::setTransactionVersion(int txVersion)
{
d->transaction.nVersion = txVersion;
}
int TransactionBuilder::transactionVersion() const
{
return d->transaction.nVersion;
}