ProtocolMessage.h

#pragma once
 
#include <xrpld/overlay/Compression.h>
#include <xrpld/overlay/Message.h>
#include <xrpld/overlay/detail/ZeroCopyStream.h>
 
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/protocol/messages.h>
 
#include <boost/asio/buffer.hpp>
#include <boost/asio/buffers_iterator.hpp>
 
#include <cstdint>
#include <optional>
#include <type_traits>
#include <vector>
 
namespace xrpl {
 
inline protocol::MessageType
protocolMessageType(protocol::TMGetLedger const&)
{
    return protocol::mtGET_LEDGER;
}
 
inline protocol::MessageType
protocolMessageType(protocol::TMReplayDeltaRequest const&)
{
    return protocol::mtREPLAY_DELTA_REQ;
}
 
inline protocol::MessageType
protocolMessageType(protocol::TMProofPathRequest const&)
{
    return protocol::mtPROOF_PATH_REQ;
}

template <class = void>
std::string
protocolMessageName(int type)
{
    switch (type)
    {
        case protocol::mtMANIFESTS:
            return "manifests";
        case protocol::mtPING:
            return "ping";
        case protocol::mtCLUSTER:
            return "cluster";
        case protocol::mtENDPOINTS:
            return "endpoints";
        case protocol::mtTRANSACTION:
            return "tx";
        case protocol::mtGET_LEDGER:
            return "get_ledger";
        case protocol::mtLEDGER_DATA:
            return "ledger_data";
        case protocol::mtPROPOSE_LEDGER:
            return "propose";
        case protocol::mtSTATUS_CHANGE:
            return "status";
        case protocol::mtHAVE_SET:
            return "have_set";
        case protocol::mtVALIDATOR_LIST:
            return "validator_list";
        case protocol::mtVALIDATOR_LIST_COLLECTION:
            return "validator_list_collection";
        case protocol::mtVALIDATION:
            return "validation";
        case protocol::mtGET_OBJECTS:
            return "get_objects";
        case protocol::mtHAVE_TRANSACTIONS:
            return "have_transactions";
        case protocol::mtTRANSACTIONS:
            return "transactions";
        case protocol::mtSQUELCH:
            return "squelch";
        case protocol::mtPROOF_PATH_REQ:
            return "proof_path_request";
        case protocol::mtPROOF_PATH_RESPONSE:
            return "proof_path_response";
        case protocol::mtREPLAY_DELTA_REQ:
            return "replay_delta_request";
        case protocol::mtREPLAY_DELTA_RESPONSE:
            return "replay_delta_response";
        default:
            break;
    }
    return "unknown";
}
 
namespace detail {
 
struct MessageHeader
{
    std::uint32_t totalWireSize = 0;

    std::uint32_t headerSize = 0;

    std::uint32_t payloadWireSize = 0;

    std::uint32_t uncompressedSize = 0;

    std::uint16_t messageType = 0;

    compression::Algorithm algorithm = compression::Algorithm::None;
};
 
template <typename BufferSequence>
auto
buffersBegin(BufferSequence const& bufs)
{
    return boost::asio::buffers_iterator<BufferSequence, std::uint8_t>::begin(bufs);
}
 
template <typename BufferSequence>
auto
buffersEnd(BufferSequence const& bufs)
{
    return boost::asio::buffers_iterator<BufferSequence, std::uint8_t>::end(bufs);
}

template <class BufferSequence>
std::optional<MessageHeader>
parseMessageHeader(boost::system::error_code& ec, BufferSequence const& bufs, std::size_t size)
{
    using namespace xrpl::compression;
 
    MessageHeader hdr;
    auto iter = buffersBegin(bufs);
    XRPL_ASSERT(iter != buffersEnd(bufs), "xrpl::detail::parseMessageHeader : non-empty buffer");
 
    // Check valid header compressed message:
    // - 4 bits are the compression algorithm, 1st bit is always set to 1
    // - 2 bits are always set to 0
    // - 26 bits are the payload size
    // - 32 bits are the uncompressed data size
    if (*iter & 0x80)
    {
        hdr.headerSize = kHeaderBytesCompressed;
 
        // not enough bytes to parse the header
        if (size < hdr.headerSize)
        {
            ec = make_error_code(boost::system::errc::success);
            return std::nullopt;
        }
 
        if (*iter & 0x0C)
        {
            ec = make_error_code(boost::system::errc::protocol_error);
            return std::nullopt;
        }
 
        hdr.algorithm = static_cast<compression::Algorithm>(*iter & 0xF0);
 
        if (hdr.algorithm != compression::Algorithm::LZ4)
        {
            ec = make_error_code(boost::system::errc::protocol_error);
            return std::nullopt;
        }
 
        for (int i = 0; i != 4; ++i)
            hdr.payloadWireSize = (hdr.payloadWireSize << 8) + *iter++;
 
        // clear the top four bits (the compression bits).
        hdr.payloadWireSize &= 0x0FFFFFFF;
 
        hdr.totalWireSize = hdr.headerSize + hdr.payloadWireSize;
 
        for (int i = 0; i != 2; ++i)
            hdr.messageType = (hdr.messageType << 8) + *iter++;
 
        for (int i = 0; i != 4; ++i)
            hdr.uncompressedSize = (hdr.uncompressedSize << 8) + *iter++;
 
        return hdr;
    }
 
    // Check valid header uncompressed message:
    // - 6 bits are set to 0
    // - 26 bits are the payload size
    if ((*iter & 0xFC) == 0)
    {
        hdr.headerSize = kHeaderBytes;
 
        if (size < hdr.headerSize)
        {
            ec = make_error_code(boost::system::errc::success);
            return std::nullopt;
        }
 
        hdr.algorithm = Algorithm::None;
 
        for (int i = 0; i != 4; ++i)
            hdr.payloadWireSize = (hdr.payloadWireSize << 8) + *iter++;
 
        hdr.uncompressedSize = hdr.payloadWireSize;
        hdr.totalWireSize = hdr.headerSize + hdr.payloadWireSize;
 
        for (int i = 0; i != 2; ++i)
            hdr.messageType = (hdr.messageType << 8) + *iter++;
 
        return hdr;
    }
 
    ec = make_error_code(boost::system::errc::no_message);
    return std::nullopt;
}
 
template <
    class T,
    class Buffers,
    class = std::enable_if_t<std::is_base_of_v<::google::protobuf::Message, T>>>
std::shared_ptr<T>
parseMessageContent(MessageHeader const& header, Buffers const& buffers)
{
    auto m = std::make_shared<T>();
 
    ZeroCopyInputStream<Buffers> stream(buffers);
    stream.Skip(header.headerSize);
 
    if (header.algorithm != compression::Algorithm::None)
    {
        std::vector<std::uint8_t> payload;
        payload.resize(header.uncompressedSize);
 
        auto const payloadSize = xrpl::compression::decompress(
            stream,
            header.payloadWireSize,
            payload.data(),
            header.uncompressedSize,
            header.algorithm);
 
        if (payloadSize == 0 || !m->ParseFromArray(payload.data(), payloadSize))
            return {};
    }
    else if (!m->ParseFromZeroCopyStream(&stream))
    {
        return {};
    }
 
    return m;
}
 
template <
    class T,
    class Buffers,
    class Handler,
    class = std::enable_if_t<std::is_base_of_v<::google::protobuf::Message, T>>>
bool
invoke(MessageHeader const& header, Buffers const& buffers, Handler& handler)
{
    auto const m = parseMessageContent<T>(header, buffers);
    if (!m)
        return false;
 
    using namespace xrpl::compression;
    handler.onMessageBegin(
        header.messageType,
        m,
        header.payloadWireSize,
        header.uncompressedSize,
        header.algorithm != Algorithm::None);
    handler.onMessage(m);
    handler.onMessageEnd(header.messageType, m);
 
    return true;
}
 
}  // namespace detail

template <class Buffers, class Handler>
std::pair<std::size_t, boost::system::error_code>
invokeProtocolMessage(Buffers const& buffers, Handler& handler, std::size_t& hint)
{
    std::pair<std::size_t, boost::system::error_code> result = {0, {}};
 
    auto const size = boost::asio::buffer_size(buffers);
 
    if (size == 0)
        return result;
 
    auto header = detail::parseMessageHeader(result.second, buffers, size);
 
    // If we can't parse the header then it may be that we don't have enough
    // bytes yet, or because the message was cut off (if error_code is success).
    // Otherwise we failed to match the header's marker (error_code is set to
    // no_message) or the compression algorithm is invalid (error_code is
    // protocol_error) and signal an error.
    if (!header)
        return result;
 
    // We implement a maximum size for protocol messages. Sending a message
    // whose size exceeds this may result in the connection being dropped. A
    // larger message size may be supported in the future or negotiated as
    // part of a protocol upgrade.
    if (header->payloadWireSize > kMaximumMessageSize ||
        header->uncompressedSize > kMaximumMessageSize)
    {
        result.second = make_error_code(boost::system::errc::message_size);
        return result;
    }
 
    // We requested uncompressed messages from the peer but received compressed.
    if (!handler.compressionEnabled() && header->algorithm != compression::Algorithm::None)
    {
        result.second = make_error_code(boost::system::errc::protocol_error);
        return result;
    }
 
    // We don't have the whole message yet. This isn't an error but we have
    // nothing to do.
    if (header->totalWireSize > size)
    {
        hint = header->totalWireSize - size;
        return result;
    }
 
    bool success = false;
 
    switch (header->messageType)
    {
        case protocol::mtMANIFESTS:
            success = detail::invoke<protocol::TMManifests>(*header, buffers, handler);
            break;
        case protocol::mtPING:
            success = detail::invoke<protocol::TMPing>(*header, buffers, handler);
            break;
        case protocol::mtCLUSTER:
            success = detail::invoke<protocol::TMCluster>(*header, buffers, handler);
            break;
        case protocol::mtENDPOINTS:
            success = detail::invoke<protocol::TMEndpoints>(*header, buffers, handler);
            break;
        case protocol::mtTRANSACTION:
            success = detail::invoke<protocol::TMTransaction>(*header, buffers, handler);
            break;
        case protocol::mtGET_LEDGER:
            success = detail::invoke<protocol::TMGetLedger>(*header, buffers, handler);
            break;
        case protocol::mtLEDGER_DATA:
            success = detail::invoke<protocol::TMLedgerData>(*header, buffers, handler);
            break;
        case protocol::mtPROPOSE_LEDGER:
            success = detail::invoke<protocol::TMProposeSet>(*header, buffers, handler);
            break;
        case protocol::mtSTATUS_CHANGE:
            success = detail::invoke<protocol::TMStatusChange>(*header, buffers, handler);
            break;
        case protocol::mtHAVE_SET:
            success = detail::invoke<protocol::TMHaveTransactionSet>(*header, buffers, handler);
            break;
        case protocol::mtVALIDATION:
            success = detail::invoke<protocol::TMValidation>(*header, buffers, handler);
            break;
        case protocol::mtVALIDATOR_LIST:
            success = detail::invoke<protocol::TMValidatorList>(*header, buffers, handler);
            break;
        case protocol::mtVALIDATOR_LIST_COLLECTION:
            success =
                detail::invoke<protocol::TMValidatorListCollection>(*header, buffers, handler);
            break;
        case protocol::mtGET_OBJECTS:
            success = detail::invoke<protocol::TMGetObjectByHash>(*header, buffers, handler);
            break;
        case protocol::mtHAVE_TRANSACTIONS:
            success = detail::invoke<protocol::TMHaveTransactions>(*header, buffers, handler);
            break;
        case protocol::mtTRANSACTIONS:
            success = detail::invoke<protocol::TMTransactions>(*header, buffers, handler);
            break;
        case protocol::mtSQUELCH:
            success = detail::invoke<protocol::TMSquelch>(*header, buffers, handler);
            break;
        case protocol::mtPROOF_PATH_REQ:
            success = detail::invoke<protocol::TMProofPathRequest>(*header, buffers, handler);
            break;
        case protocol::mtPROOF_PATH_RESPONSE:
            success = detail::invoke<protocol::TMProofPathResponse>(*header, buffers, handler);
            break;
        case protocol::mtREPLAY_DELTA_REQ:
            success = detail::invoke<protocol::TMReplayDeltaRequest>(*header, buffers, handler);
            break;
        case protocol::mtREPLAY_DELTA_RESPONSE:
            success = detail::invoke<protocol::TMReplayDeltaResponse>(*header, buffers, handler);
            break;
        default:
            handler.onMessageUnknown(header->messageType);
            success = true;
            break;
    }
 
    result.first = header->totalWireSize;
 
    if (!success)
        result.second = make_error_code(boost::system::errc::bad_message);
 
    return result;
}
 
}  // namespace xrpl