[gui] PSBT Operations Dialog (sign & broadcast)

Add a "PSBT Operations" dialog, reached from the "Load PSBT..." menu
item, giving options to sign or broadcast the loaded PSBT as
appropriate, as well as copying the result to the clipboard or saving
it to a file.

1 files changed, 268 insertions, 0 deletions

diff --git a/src/qt/psbtoperationsdialog.cpp b/src/qt/psbtoperationsdialog.cpp
new file mode 100644
index 0000000000..58167d4bb4
--- /dev/null
+++ b/src/qt/psbtoperationsdialog.cpp
@@ -0,0 +1,268 @@
+// Copyright (c) 2011-2020 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 <qt/psbtoperationsdialog.h>
+
+#include <core_io.h>
+#include <interfaces/node.h>
+#include <key_io.h>
+#include <node/psbt.h>
+#include <policy/policy.h>
+#include <qt/bitcoinunits.h>
+#include <qt/forms/ui_psbtoperationsdialog.h>
+#include <qt/guiutil.h>
+#include <qt/optionsmodel.h>
+#include <util/strencodings.h>
+
+#include <iostream>
+
+
+PSBTOperationsDialog::PSBTOperationsDialog(
+    QWidget* parent, WalletModel* wallet_model, ClientModel* client_model) : QDialog(parent),
+                                                                             m_ui(new Ui::PSBTOperationsDialog),
+                                                                             m_wallet_model(wallet_model),
+                                                                             m_client_model(client_model)
+{
+    m_ui->setupUi(this);
+    setWindowTitle("PSBT Operations");
+
+    connect(m_ui->signTransactionButton, &QPushButton::clicked, this, &PSBTOperationsDialog::signTransaction);
+    connect(m_ui->broadcastTransactionButton, &QPushButton::clicked, this, &PSBTOperationsDialog::broadcastTransaction);
+    connect(m_ui->copyToClipboardButton, &QPushButton::clicked, this, &PSBTOperationsDialog::copyToClipboard);
+    connect(m_ui->saveButton, &QPushButton::clicked, this, &PSBTOperationsDialog::saveTransaction);
+
+    connect(m_ui->closeButton, &QPushButton::clicked, this, &PSBTOperationsDialog::close);
+
+    m_ui->signTransactionButton->setEnabled(false);
+    m_ui->broadcastTransactionButton->setEnabled(false);
+}
+
+PSBTOperationsDialog::~PSBTOperationsDialog()
+{
+    delete m_ui;
+}
+
+void PSBTOperationsDialog::openWithPSBT(PartiallySignedTransaction psbtx)
+{
+    m_transaction_data = psbtx;
+
+    bool complete;
+    size_t n_could_sign;
+    FinalizePSBT(psbtx);  // Make sure all existing signatures are fully combined before checking for completeness.
+    TransactionError err = m_wallet_model->wallet().fillPSBT(SIGHASH_ALL, false /* sign */, true /* bip32derivs */,  m_transaction_data, complete, &n_could_sign);
+    if (err != TransactionError::OK) {
+        showStatus(tr("Failed to load transaction: %1")
+            .arg(QString::fromStdString(TransactionErrorString(err).translated)), StatusLevel::ERR);
+        return;
+    }
+
+    m_ui->broadcastTransactionButton->setEnabled(complete);
+    m_ui->signTransactionButton->setEnabled(!complete && !m_wallet_model->wallet().privateKeysDisabled() && n_could_sign > 0);
+
+    updateTransactionDisplay();
+}
+
+void PSBTOperationsDialog::signTransaction()
+{
+    bool complete;
+    size_t n_signed;
+    TransactionError err = m_wallet_model->wallet().fillPSBT(SIGHASH_ALL, true /* sign */, true /* bip32derivs */, m_transaction_data, complete, &n_signed);
+
+    if (err != TransactionError::OK) {
+        showStatus(tr("Failed to sign transaction: %1")
+            .arg(QString::fromStdString(TransactionErrorString(err).translated)), StatusLevel::ERR);
+        return;
+    }
+
+    updateTransactionDisplay();
+
+    if (!complete && n_signed < 1) {
+        showStatus(tr("Could not sign any more inputs."), StatusLevel::WARN);
+    } else if (!complete) {
+        showStatus(tr("Signed %1 inputs, but more signatures are still required.").arg(n_signed),
+            StatusLevel::INFO);
+    } else {
+        showStatus(tr("Signed transaction successfully. Transaction is ready to broadcast."),
+            StatusLevel::INFO);
+        m_ui->broadcastTransactionButton->setEnabled(true);
+    }
+}
+
+void PSBTOperationsDialog::broadcastTransaction()
+{
+    CMutableTransaction mtx;
+    if (!FinalizeAndExtractPSBT(m_transaction_data, mtx)) {
+        // This is never expected to fail unless we were given a malformed PSBT
+        // (e.g. with an invalid signature.)
+        showStatus(tr("Unknown error processing transaction."), StatusLevel::ERR);
+        return;
+    }
+
+    CTransactionRef tx = MakeTransactionRef(mtx);
+    std::string err_string;
+    TransactionError error = BroadcastTransaction(
+        *m_client_model->node().context(), tx, err_string, DEFAULT_MAX_RAW_TX_FEE_RATE.GetFeePerK(), /* relay */ true, /* await_callback */ false);
+
+    if (error == TransactionError::OK) {
+        showStatus(tr("Transaction broadcast successfully! Transaction ID: %1")
+            .arg(QString::fromStdString(tx->GetHash().GetHex())), StatusLevel::INFO);
+    } else {
+        showStatus(tr("Transaction broadcast failed: %1")
+            .arg(QString::fromStdString(TransactionErrorString(error).translated)), StatusLevel::ERR);
+    }
+}
+
+void PSBTOperationsDialog::copyToClipboard() {
+    CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
+    ssTx << m_transaction_data;
+    GUIUtil::setClipboard(EncodeBase64(ssTx.str()).c_str());
+    showStatus(tr("PSBT copied to clipboard."), StatusLevel::INFO);
+}
+
+void PSBTOperationsDialog::saveTransaction() {
+    CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
+    ssTx << m_transaction_data;
+
+    QString selected_filter;
+    QString filename_suggestion = "";
+    bool first = true;
+    for (const CTxOut& out : m_transaction_data.tx->vout) {
+        if (!first) {
+            filename_suggestion.append("-");
+        }
+        CTxDestination address;
+        ExtractDestination(out.scriptPubKey, address);
+        QString amount = BitcoinUnits::format(m_wallet_model->getOptionsModel()->getDisplayUnit(), out.nValue);
+        QString address_str = QString::fromStdString(EncodeDestination(address));
+        filename_suggestion.append(address_str + "-" + amount);
+        first = false;
+    }
+    filename_suggestion.append(".psbt");
+    QString filename = GUIUtil::getSaveFileName(this,
+        tr("Save Transaction Data"), filename_suggestion,
+        tr("Partially Signed Transaction (Binary) (*.psbt)"), &selected_filter);
+    if (filename.isEmpty()) {
+        return;
+    }
+    std::ofstream out(filename.toLocal8Bit().data());
+    out << ssTx.str();
+    out.close();
+    showStatus(tr("PSBT saved to disk."), StatusLevel::INFO);
+}
+
+void PSBTOperationsDialog::updateTransactionDisplay() {
+    m_ui->transactionDescription->setText(QString::fromStdString(renderTransaction(m_transaction_data)));
+    showTransactionStatus(m_transaction_data);
+}
+
+std::string PSBTOperationsDialog::renderTransaction(const PartiallySignedTransaction &psbtx)
+{
+    QString tx_description = "";
+    CAmount totalAmount = 0;
+    for (const CTxOut& out : psbtx.tx->vout) {
+        CTxDestination address;
+        ExtractDestination(out.scriptPubKey, address);
+        totalAmount += out.nValue;
+        tx_description.append(tr(" * Sends %1 to %2")
+            .arg(BitcoinUnits::formatWithUnit(BitcoinUnits::BTC, out.nValue))
+            .arg(QString::fromStdString(EncodeDestination(address))));
+        tx_description.append("<br>");
+    }
+
+    PSBTAnalysis analysis = AnalyzePSBT(psbtx);
+    tx_description.append(" * ");
+    if (!*analysis.fee) {
+        // This happens if the transaction is missing input UTXO information.
+        tx_description.append(tr("Unable to calculate transaction fee or total transaction amount."));
+    } else {
+        tx_description.append(tr("Pays transaction fee: "));
+        tx_description.append(BitcoinUnits::formatWithUnit(BitcoinUnits::BTC, *analysis.fee));
+
+        // add total amount in all subdivision units
+        tx_description.append("<hr />");
+        QStringList alternativeUnits;
+        for (const BitcoinUnits::Unit u : BitcoinUnits::availableUnits())
+        {
+            if(u != m_client_model->getOptionsModel()->getDisplayUnit()) {
+                alternativeUnits.append(BitcoinUnits::formatHtmlWithUnit(u, totalAmount));
+            }
+        }
+        tx_description.append(QString("<b>%1</b>: <b>%2</b>").arg(tr("Total Amount"))
+            .arg(BitcoinUnits::formatHtmlWithUnit(m_client_model->getOptionsModel()->getDisplayUnit(), totalAmount)));
+        tx_description.append(QString("<br /><span style='font-size:10pt; font-weight:normal;'>(=%1)</span>")
+            .arg(alternativeUnits.join(" " + tr("or") + " ")));
+    }
+
+    size_t num_unsigned = CountPSBTUnsignedInputs(psbtx);
+    if (num_unsigned > 0) {
+        tx_description.append("<br><br>");
+        tx_description.append(tr("Transaction has %1 unsigned inputs.").arg(QString::number(num_unsigned)));
+    }
+
+    return tx_description.toStdString();
+}
+
+void PSBTOperationsDialog::showStatus(const QString &msg, StatusLevel level) {
+    m_ui->statusBar->setText(msg);
+    switch (level) {
+        case StatusLevel::INFO: {
+            m_ui->statusBar->setStyleSheet("QLabel { background-color : lightgreen }");
+            break;
+        }
+        case StatusLevel::WARN: {
+            m_ui->statusBar->setStyleSheet("QLabel { background-color : orange }");
+            break;
+        }
+        case StatusLevel::ERR: {
+            m_ui->statusBar->setStyleSheet("QLabel { background-color : red }");
+            break;
+        }
+    }
+    m_ui->statusBar->show();
+}
+
+size_t PSBTOperationsDialog::couldSignInputs(const PartiallySignedTransaction &psbtx) {
+    size_t n_signed;
+    bool complete;
+    TransactionError err = m_wallet_model->wallet().fillPSBT(SIGHASH_ALL, false /* sign */, false /* bip32derivs */, m_transaction_data, complete, &n_signed);
+
+    if (err != TransactionError::OK) {
+        return 0;
+    }
+    return n_signed;
+}
+
+void PSBTOperationsDialog::showTransactionStatus(const PartiallySignedTransaction &psbtx) {
+    PSBTAnalysis analysis = AnalyzePSBT(psbtx);
+    size_t n_could_sign = couldSignInputs(psbtx);
+
+    switch (analysis.next) {
+        case PSBTRole::UPDATER: {
+            showStatus(tr("Transaction is missing some information about inputs."), StatusLevel::WARN);
+            break;
+        }
+        case PSBTRole::SIGNER: {
+            QString need_sig_text = tr("Transaction still needs signature(s).");
+            StatusLevel level = StatusLevel::INFO;
+            if (m_wallet_model->wallet().privateKeysDisabled()) {
+                need_sig_text += " " + tr("(But this wallet cannot sign transactions.)");
+                level = StatusLevel::WARN;
+            } else if (n_could_sign < 1) {
+                need_sig_text += " " + tr("(But this wallet does not have the right keys.)"); // XXX wording
+                level = StatusLevel::WARN;
+            }
+            showStatus(need_sig_text, level);
+            break;
+        }
+        case PSBTRole::FINALIZER:
+        case PSBTRole::EXTRACTOR: {
+            showStatus(tr("Transaction is fully signed and ready for broadcast."), StatusLevel::INFO);
+            break;
+        }
+        default: {
+            showStatus(tr("Transaction status is unknown."), StatusLevel::ERR);
+            break;
+        }
+    }
+}