clio/src/rpc/handlers/GatewayBalances.cpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, the clio developers.

    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#include <backend/BackendInterface.h>
#include <rpc/RPCHelpers.h>

namespace RPC {

Result
doGatewayBalances(Context const& context)
{
    auto request = context.params;
    boost::json::object response = {};

    ripple::AccountID accountID;
    if (auto const status = getAccount(request, accountID); status)
        return status;

    auto v = ledgerInfoFromRequest(context);
    if (auto status = std::get_if<Status>(&v))
        return *status;

    auto lgrInfo = std::get<ripple::LedgerInfo>(v);

    std::map<ripple::Currency, ripple::STAmount> sums;
    std::map<ripple::AccountID, std::vector<ripple::STAmount>> hotBalances;
    std::map<ripple::AccountID, std::vector<ripple::STAmount>> assets;
    std::map<ripple::AccountID, std::vector<ripple::STAmount>> frozenBalances;
    std::set<ripple::AccountID> hotWallets;

    if (request.contains(JS(hotwallet)))
    {
        auto getAccountID =
            [](auto const& j) -> std::optional<ripple::AccountID> {
            if (j.is_string())
            {
                auto const pk = ripple::parseBase58<ripple::PublicKey>(
                    ripple::TokenType::AccountPublic, j.as_string().c_str());
                if (pk)
                {
                    return ripple::calcAccountID(*pk);
                }

                return ripple::parseBase58<ripple::AccountID>(
                    j.as_string().c_str());
            }
            return {};
        };

        auto const& hw = request.at(JS(hotwallet));
        bool valid = true;

        // null is treated as a valid 0-sized array of hotwallet
        if (hw.is_array())
        {
            auto const& arr = hw.as_array();
            for (unsigned i = 0; i < arr.size(); ++i)
            {
                if (auto id = getAccountID(arr[i]))
                    hotWallets.insert(*id);
                else
                    valid = false;
            }
        }
        else if (hw.is_string())
        {
            if (auto id = getAccountID(hw))
                hotWallets.insert(*id);
            else
                valid = false;
        }
        else
        {
            valid = false;
        }

        if (!valid)
        {
            response[JS(error)] = "invalidHotWallet";
            return response;
        }
    }

    // Traverse the cold wallet's trust lines
    auto const addToResponse = [&](ripple::SLE&& sle) {
        if (sle.getType() == ripple::ltRIPPLE_STATE)
        {
            ripple::STAmount balance = sle.getFieldAmount(ripple::sfBalance);

            auto lowLimit = sle.getFieldAmount(ripple::sfLowLimit);
            auto highLimit = sle.getFieldAmount(ripple::sfHighLimit);
            auto lowID = lowLimit.getIssuer();
            auto highID = highLimit.getIssuer();
            bool viewLowest = (lowLimit.getIssuer() == accountID);
            auto lineLimit = viewLowest ? lowLimit : highLimit;
            auto lineLimitPeer = !viewLowest ? lowLimit : highLimit;
            auto flags = sle.getFieldU32(ripple::sfFlags);
            auto freeze = flags &
                (viewLowest ? ripple::lsfLowFreeze : ripple::lsfHighFreeze);
            if (!viewLowest)
                balance.negate();

            int balSign = balance.signum();
            if (balSign == 0)
                return true;

            auto const& peer = !viewLowest ? lowID : highID;

            // Here, a negative balance means the cold wallet owes (normal)
            // A positive balance means the cold wallet has an asset
            // (unusual)

            if (hotWallets.count(peer) > 0)
            {
                // This is a specified hot wallet
                hotBalances[peer].push_back(-balance);
            }
            else if (balSign > 0)
            {
                // This is a gateway asset
                assets[peer].push_back(balance);
            }
            else if (freeze)
            {
                // An obligation the gateway has frozen
                frozenBalances[peer].push_back(-balance);
            }
            else
            {
                // normal negative balance, obligation to customer
                auto& bal = sums[balance.getCurrency()];
                if (bal == beast::zero)
                {
                    // This is needed to set the currency code correctly
                    bal = -balance;
                }
                else
                {  // when overflow happens, insert a flag to indicate
                   // https://github.com/XRPLF/rippled/pull/4355
                    try
                    {
                        bal -= balance;
                    }
                    catch (std::runtime_error& e)
                    {
                        response["overflow"] = true;
                    }
                }
            }
        }
        return true;
    };

    auto result = traverseOwnedNodes(
        *context.backend,
        accountID,
        lgrInfo.seq,
        std::numeric_limits<std::uint32_t>::max(),
        {},
        context.yield,
        addToResponse);
    if (auto status = std::get_if<RPC::Status>(&result))
        return *status;

    if (!sums.empty())
    {
        boost::json::object obj;
        for (auto const& [k, v] : sums)
        {
            obj[ripple::to_string(k)] = v.getText();
        }
        response[JS(obligations)] = std::move(obj);
    }

    auto toJson =
        [](std::map<ripple::AccountID, std::vector<ripple::STAmount>> const&
               balances) {
            boost::json::object obj;
            if (!balances.empty())
            {
                for (auto const& [accId, accBalances] : balances)
                {
                    boost::json::array arr;
                    for (auto const& balance : accBalances)
                    {
                        boost::json::object entry;
                        entry[JS(currency)] =
                            ripple::to_string(balance.issue().currency);
                        entry[JS(value)] = balance.getText();
                        arr.push_back(std::move(entry));
                    }
                    obj[ripple::to_string(accId)] = std::move(arr);
                }
            }
            return obj;
        };

    auto containsHotWallet = [&](auto const& hw) {
        return hotBalances.contains(hw);
    };
    if (not std::all_of(
            hotWallets.begin(), hotWallets.end(), containsHotWallet))
        return Status{RippledError::rpcINVALID_PARAMS, "invalidHotWallet"};

    if (auto balances = toJson(hotBalances); balances.size())
        response[JS(balances)] = balances;
    if (auto balances = toJson(frozenBalances); balances.size())
        response[JS(frozen_balances)] = balances;
    if (auto balances = toJson(assets); assets.size())
        response[JS(assets)] = toJson(assets);
    response[JS(account)] = request.at(JS(account));
    response[JS(ledger_index)] = lgrInfo.seq;
    response[JS(ledger_hash)] = ripple::strHex(lgrInfo.hash);
    return response;
}
}  // namespace RPC