transaction.cpp

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// Copyright (c) 2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <consensus/validation.h>
#include <index/txindex.h>
#include <net.h>
#include <net_processing.h>
#include <node/blockstorage.h>
#include <node/context.h>
#include <node/types.h>
#include <txmempool.h>
#include <validation.h>
#include <validationinterface.h>
#include <node/transaction.h>
 
#include <future>
 
namespace node {
static TransactionError HandleATMPError(const TxValidationState& state, std::string& err_string_out)
{
    err_string_out = state.ToString();
    if (state.IsInvalid()) {
        if (state.GetResult() == TxValidationResult::TX_MISSING_INPUTS) {
            return TransactionError::MISSING_INPUTS;
        }
        return TransactionError::MEMPOOL_REJECTED;
    } else {
        return TransactionError::MEMPOOL_ERROR;
    }
}
 
TransactionError BroadcastTransaction(NodeContext& node,
                                      const CTransactionRef tx,
                                      std::string& err_string,
                                      const CAmount& max_tx_fee,
                                      TxBroadcast broadcast_method,
                                      bool wait_callback)
{
    // BroadcastTransaction can be called by RPC or by the wallet.
    // chainman, mempool and peerman are initialized before the RPC server and wallet are started
    // and reset after the RPC sever and wallet are stopped.
    assert(node.chainman);
    assert(node.mempool);
    assert(node.peerman);
 
    std::promise<void> promise;
    Txid txid = tx->GetHash();
    Wtxid wtxid = tx->GetWitnessHash();
    bool callback_set = false;
 
    {
        LOCK(cs_main);
 
        // If the transaction is already confirmed in the chain, don't do anything
        // and return early.
        CCoinsViewCache &view = node.chainman->ActiveChainstate().CoinsTip();
        for (size_t o = 0; o < tx->vout.size(); o++) {
            const Coin& existingCoin = view.AccessCoin(COutPoint(txid, o));
            // IsSpent doesn't mean the coin is spent, it means the output doesn't exist.
            // So if the output does exist, then this transaction exists in the chain.
            if (!existingCoin.IsSpent()) return TransactionError::ALREADY_IN_UTXO_SET;
        }
 
        if (auto mempool_tx = node.mempool->get(txid); mempool_tx) {
            // There's already a transaction in the mempool with this txid. Don't
            // try to submit this transaction to the mempool (since it'll be
            // rejected as a TX_CONFLICT), but do attempt to reannounce the mempool
            // transaction if broadcast_method is not TxBroadcast::MEMPOOL_NO_BROADCAST.
            //
            // The mempool transaction may have the same or different witness (and
            // wtxid) as this transaction. Use the mempool's wtxid for reannouncement.
            wtxid = mempool_tx->GetWitnessHash();
        } else {
            // Transaction is not already in the mempool.
            if (max_tx_fee > 0) {
                // First, call ATMP with test_accept and check the fee. If ATMP
                // fails here, return error immediately.
                const MempoolAcceptResult result = node.chainman->ProcessTransaction(tx, /*test_accept=*/ true);
                if (result.m_result_type != MempoolAcceptResult::ResultType::VALID) {
                    return HandleATMPError(result.m_state, err_string);
                } else if (result.m_base_fees.value() > max_tx_fee) {
                    return TransactionError::MAX_FEE_EXCEEDED;
                }
            }
 
            switch (broadcast_method) {
            case TxBroadcast::MEMPOOL_NO_BROADCAST:
            case TxBroadcast::MEMPOOL_AND_BROADCAST_TO_ALL:
                // Try to submit the transaction to the mempool.
                {
                    const MempoolAcceptResult result =
                        node.chainman->ProcessTransaction(tx, /*test_accept=*/false);
                    if (result.m_result_type != MempoolAcceptResult::ResultType::VALID) {
                        return HandleATMPError(result.m_state, err_string);
                    }
                }
                // Transaction was accepted to the mempool.
 
                if (broadcast_method == TxBroadcast::MEMPOOL_AND_BROADCAST_TO_ALL) {
                    // the mempool tracks locally submitted transactions to make a
                    // best-effort of initial broadcast
                    node.mempool->AddUnbroadcastTx(txid);
                }
                break;
            }
 
            if (wait_callback && node.validation_signals) {
                // For transactions broadcast from outside the wallet, make sure
                // that the wallet has been notified of the transaction before
                // continuing.
                //
                // This prevents a race where a user might call sendrawtransaction
                // with a transaction to/from their wallet, immediately call some
                // wallet RPC, and get a stale result because callbacks have not
                // yet been processed.
                node.validation_signals->CallFunctionInValidationInterfaceQueue([&promise] {
                    promise.set_value();
                });
                callback_set = true;
            }
        }
    } // cs_main
 
    if (callback_set) {
        // Wait until Validation Interface clients have been notified of the
        // transaction entering the mempool.
        promise.get_future().wait();
    }
 
    switch (broadcast_method) {
    case TxBroadcast::MEMPOOL_NO_BROADCAST:
        break;
    case TxBroadcast::MEMPOOL_AND_BROADCAST_TO_ALL:
        node.peerman->RelayTransaction(txid, wtxid);
        break;
    }
 
    return TransactionError::OK;
}
 
CTransactionRef GetTransaction(const CBlockIndex* const block_index, const CTxMemPool* const mempool, const Txid& hash, const BlockManager& blockman, uint256& hashBlock)
{
    if (mempool && !block_index) {
        CTransactionRef ptx = mempool->get(hash);
        if (ptx) return ptx;
    }
    if (g_txindex) {
        CTransactionRef tx;
        uint256 block_hash;
        if (g_txindex->FindTx(hash, block_hash, tx)) {
            if (!block_index || block_index->GetBlockHash() == block_hash) {
                // Don't return the transaction if the provided block hash doesn't match.
                // The case where a transaction appears in multiple blocks (e.g. reorgs or
                // BIP30) is handled by the block lookup below.
                hashBlock = block_hash;
                return tx;
            }
        }
    }
    if (block_index) {
        CBlock block;
        if (blockman.ReadBlock(block, *block_index)) {
            for (const auto& tx : block.vtx) {
                if (tx->GetHash() == hash) {
                    hashBlock = block_index->GetBlockHash();
                    return tx;
                }
            }
        }
    }
    return nullptr;
}
} // namespace node