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rpc/wallet: add simulaterawtransaction RPC

This command iterates over the inputs and outputs of the given transactions, and tallies up the balance change for the given wallet. This can be useful e.g. when verifying that a coin join like transaction doesn't contain unexpected inputs that the wallet will then sign for unintentionally.
This commit is contained in:
Karl-Johan Alm 2021-08-20 15:09:03 +09:00
parent 701a64f548
commit db10cf8ae3
No known key found for this signature in database
GPG key ID: 57AF762DB3353322
4 changed files with 245 additions and 0 deletions

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@ -147,6 +147,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
{ "sendall", 1, "conf_target" },
{ "sendall", 3, "fee_rate"},
{ "sendall", 4, "options" },
{ "simulaterawtransaction", 0, "rawtxs" },
{ "simulaterawtransaction", 1, "options" },
{ "importprivkey", 2, "rescan" },
{ "importaddress", 2, "rescan" },
{ "importaddress", 3, "p2sh" },

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@ -590,6 +590,117 @@ static RPCHelpMan upgradewallet()
};
}
RPCHelpMan simulaterawtransaction()
{
return RPCHelpMan{"simulaterawtransaction",
"\nCalculate the balance change resulting in the signing and broadcasting of the given transaction(s).\n",
{
{"rawtxs", RPCArg::Type::ARR, RPCArg::Optional::OMITTED_NAMED_ARG, "An array of hex strings of raw transactions.\n",
{
{"rawtx", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, ""},
},
},
{"options", RPCArg::Type::OBJ_USER_KEYS, RPCArg::Optional::OMITTED_NAMED_ARG, "Options",
{
{"include_watchonly", RPCArg::Type::BOOL, RPCArg::DefaultHint{"true for watch-only wallets, otherwise false"}, "Whether to include watch-only addresses (see RPC importaddress)"},
},
},
},
RPCResult{
RPCResult::Type::OBJ, "", "",
{
{RPCResult::Type::STR_AMOUNT, "balance_change", "The wallet balance change (negative means decrease)."},
}
},
RPCExamples{
HelpExampleCli("simulaterawtransaction", "[\"myhex\"]")
+ HelpExampleRpc("simulaterawtransaction", "[\"myhex\"]")
},
[&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
const std::shared_ptr<const CWallet> rpc_wallet = GetWalletForJSONRPCRequest(request);
if (!rpc_wallet) return UniValue::VNULL;
const CWallet& wallet = *rpc_wallet;
RPCTypeCheck(request.params, {UniValue::VARR, UniValue::VOBJ}, true);
LOCK(wallet.cs_wallet);
UniValue include_watchonly(UniValue::VNULL);
if (request.params[1].isObject()) {
UniValue options = request.params[1];
RPCTypeCheckObj(options,
{
{"include_watchonly", UniValueType(UniValue::VBOOL)},
},
true, true);
include_watchonly = options["include_watchonly"];
}
isminefilter filter = ISMINE_SPENDABLE;
if (ParseIncludeWatchonly(include_watchonly, wallet)) {
filter |= ISMINE_WATCH_ONLY;
}
const auto& txs = request.params[0].get_array();
CAmount changes{0};
std::map<COutPoint, CAmount> new_utxos; // UTXO:s that were made available in transaction array
std::set<COutPoint> spent;
for (size_t i = 0; i < txs.size(); ++i) {
CMutableTransaction mtx;
if (!DecodeHexTx(mtx, txs[i].get_str(), /* try_no_witness */ true, /* try_witness */ true)) {
throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Transaction hex string decoding failure.");
}
// Fetch previous transactions (inputs)
std::map<COutPoint, Coin> coins;
for (const CTxIn& txin : mtx.vin) {
coins[txin.prevout]; // Create empty map entry keyed by prevout.
}
wallet.chain().findCoins(coins);
// Fetch debit; we are *spending* these; if the transaction is signed and
// broadcast, we will lose everything in these
for (const auto& txin : mtx.vin) {
const auto& outpoint = txin.prevout;
if (spent.count(outpoint)) {
throw JSONRPCError(RPC_INVALID_PARAMETER, "Transaction(s) are spending the same output more than once");
}
if (new_utxos.count(outpoint)) {
changes -= new_utxos.at(outpoint);
new_utxos.erase(outpoint);
} else {
if (coins.at(outpoint).IsSpent()) {
throw JSONRPCError(RPC_INVALID_PARAMETER, "One or more transaction inputs are missing or have been spent already");
}
changes -= wallet.GetDebit(txin, filter);
}
spent.insert(outpoint);
}
// Iterate over outputs; we are *receiving* these, if the wallet considers
// them "mine"; if the transaction is signed and broadcast, we will receive
// everything in these
// Also populate new_utxos in case these are spent in later transactions
const auto& hash = mtx.GetHash();
for (size_t i = 0; i < mtx.vout.size(); ++i) {
const auto& txout = mtx.vout[i];
bool is_mine = 0 < (wallet.IsMine(txout) & filter);
changes += new_utxos[COutPoint(hash, i)] = is_mine ? txout.nValue : 0;
}
}
UniValue result(UniValue::VOBJ);
result.pushKV("balance_change", ValueFromAmount(changes));
return result;
}
};
}
// addresses
RPCHelpMan getaddressinfo();
RPCHelpMan getnewaddress();
@ -721,6 +832,7 @@ Span<const CRPCCommand> GetWalletRPCCommands()
{"wallet", &setwalletflag},
{"wallet", &signmessage},
{"wallet", &signrawtransactionwithwallet},
{"wallet", &simulaterawtransaction},
{"wallet", &sendall},
{"wallet", &unloadwallet},
{"wallet", &upgradewallet},

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@ -265,6 +265,8 @@ BASE_SCRIPTS = [
'wallet_implicitsegwit.py --legacy-wallet',
'rpc_named_arguments.py',
'feature_startupnotify.py',
'wallet_simulaterawtx.py --legacy-wallet',
'wallet_simulaterawtx.py --descriptors',
'wallet_listsinceblock.py --legacy-wallet',
'wallet_listsinceblock.py --descriptors',
'wallet_listdescriptors.py --descriptors',

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@ -0,0 +1,129 @@
#!/usr/bin/env python3
# Copyright (c) 2021 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test simulaterawtransaction.
"""
from decimal import Decimal
from test_framework.blocktools import COINBASE_MATURITY
from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import (
assert_approx,
assert_equal,
assert_raises_rpc_error,
)
class SimulateTxTest(BitcoinTestFramework):
def set_test_params(self):
self.setup_clean_chain = True
self.num_nodes = 1
def skip_test_if_missing_module(self):
self.skip_if_no_wallet()
def setup_network(self, split=False):
self.setup_nodes()
def run_test(self):
node = self.nodes[0]
self.generate(node, 1, sync_fun=self.no_op) # Leave IBD
node.createwallet(wallet_name='w0')
node.createwallet(wallet_name='w1')
node.createwallet(wallet_name='w2', disable_private_keys=True)
w0 = node.get_wallet_rpc('w0')
w1 = node.get_wallet_rpc('w1')
w2 = node.get_wallet_rpc('w2')
self.generatetoaddress(node, COINBASE_MATURITY + 1, w0.getnewaddress())
assert_equal(w0.getbalance(), 50.0)
assert_equal(w1.getbalance(), 0.0)
address1 = w1.getnewaddress()
address2 = w1.getnewaddress()
# Add address1 as watch-only to w2
w2.importpubkey(pubkey=w1.getaddressinfo(address1)["pubkey"])
tx1 = node.createrawtransaction([], [{address1: 5.0}])
tx2 = node.createrawtransaction([], [{address2: 10.0}])
# w0 should be unaffected, w2 should see +5 for tx1
assert_equal(w0.simulaterawtransaction([tx1])["balance_change"], 0.0)
assert_equal(w2.simulaterawtransaction([tx1])["balance_change"], 5.0)
# w1 should see +5 balance for tx1
assert_equal(w1.simulaterawtransaction([tx1])["balance_change"], 5.0)
# w0 should be unaffected, w2 should see +5 for both transactions
assert_equal(w0.simulaterawtransaction([tx1, tx2])["balance_change"], 0.0)
assert_equal(w2.simulaterawtransaction([tx1, tx2])["balance_change"], 5.0)
# w1 should see +15 balance for both transactions
assert_equal(w1.simulaterawtransaction([tx1, tx2])["balance_change"], 15.0)
# w0 funds transaction; it should now see a decrease in (tx fee and payment), and w1 should see the same as above
funding = w0.fundrawtransaction(tx1)
tx1 = funding["hex"]
tx1changepos = funding["changepos"]
bitcoin_fee = Decimal(funding["fee"])
# w0 sees fee + 5 btc decrease, w2 sees + 5 btc
assert_approx(w0.simulaterawtransaction([tx1])["balance_change"], -(Decimal("5") + bitcoin_fee))
assert_approx(w2.simulaterawtransaction([tx1])["balance_change"], Decimal("5"))
# w1 sees same as before
assert_equal(w1.simulaterawtransaction([tx1])["balance_change"], 5.0)
# same inputs (tx) more than once should error
assert_raises_rpc_error(-8, "Transaction(s) are spending the same output more than once", w0.simulaterawtransaction, [tx1,tx1])
tx1ob = node.decoderawtransaction(tx1)
tx1hex = tx1ob["txid"]
tx1vout = 1 - tx1changepos
# tx3 spends new w1 UTXO paying to w0
tx3 = node.createrawtransaction([{"txid": tx1hex, "vout": tx1vout}], {w0.getnewaddress(): 4.9999})
# tx4 spends new w1 UTXO paying to w1
tx4 = node.createrawtransaction([{"txid": tx1hex, "vout": tx1vout}], {w1.getnewaddress(): 4.9999})
# on their own, both should fail due to missing input(s)
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w0.simulaterawtransaction, [tx3])
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w1.simulaterawtransaction, [tx3])
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w0.simulaterawtransaction, [tx4])
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w1.simulaterawtransaction, [tx4])
# they should succeed when including tx1:
# wallet tx3 tx4
# w0 -5 - bitcoin_fee + 4.9999 -5 - bitcoin_fee
# w1 0 +4.9999
assert_approx(w0.simulaterawtransaction([tx1, tx3])["balance_change"], -Decimal("5") - bitcoin_fee + Decimal("4.9999"))
assert_approx(w1.simulaterawtransaction([tx1, tx3])["balance_change"], 0)
assert_approx(w0.simulaterawtransaction([tx1, tx4])["balance_change"], -Decimal("5") - bitcoin_fee)
assert_approx(w1.simulaterawtransaction([tx1, tx4])["balance_change"], Decimal("4.9999"))
# they should fail if attempting to include both tx3 and tx4
assert_raises_rpc_error(-8, "Transaction(s) are spending the same output more than once", w0.simulaterawtransaction, [tx1, tx3, tx4])
assert_raises_rpc_error(-8, "Transaction(s) are spending the same output more than once", w1.simulaterawtransaction, [tx1, tx3, tx4])
# send tx1 to avoid reusing same UTXO below
node.sendrawtransaction(w0.signrawtransactionwithwallet(tx1)["hex"])
self.generate(node, 1, sync_fun=self.no_op) # Confirm tx to trigger error below
self.sync_all()
# w0 funds transaction 2; it should now see a decrease in (tx fee and payment), and w1 should see the same as above
funding = w0.fundrawtransaction(tx2)
tx2 = funding["hex"]
bitcoin_fee2 = Decimal(funding["fee"])
assert_approx(w0.simulaterawtransaction([tx2])["balance_change"], -(Decimal("10") + bitcoin_fee2))
assert_approx(w1.simulaterawtransaction([tx2])["balance_change"], +(Decimal("10")))
assert_approx(w2.simulaterawtransaction([tx2])["balance_change"], 0)
# w0-w2 error due to tx1 already being mined
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w0.simulaterawtransaction, [tx1, tx2])
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w1.simulaterawtransaction, [tx1, tx2])
assert_raises_rpc_error(-8, "One or more transaction inputs are missing or have been spent already", w2.simulaterawtransaction, [tx1, tx2])
if __name__ == '__main__':
SimulateTxTest().main()