rippled/src/ripple/overlay/impl/Message.cpp

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.

    Permission to use, copy, modify, and/or 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 <ripple/overlay/Message.h>
#include <ripple/overlay/impl/TrafficCount.h>
#include <cstdint>

namespace ripple {

Message::Message(
    ::google::protobuf::Message const& message,
    int type,
    boost::optional<PublicKey> const& validator)
    : category_(TrafficCount::categorize(message, type, false))
    , validatorKey_(validator)
{
    using namespace ripple::compression;

#if defined(GOOGLE_PROTOBUF_VERSION) && (GOOGLE_PROTOBUF_VERSION >= 3011000)
    auto const messageBytes = message.ByteSizeLong();
#else
    unsigned const messageBytes = message.ByteSize();
#endif

    assert(messageBytes != 0);

    buffer_.resize(headerBytes + messageBytes);

    setHeader(buffer_.data(), messageBytes, type, Algorithm::None, 0);

    if (messageBytes != 0)
        message.SerializeToArray(buffer_.data() + headerBytes, messageBytes);
}

void
Message::compress()
{
    using namespace ripple::compression;
    auto const messageBytes = buffer_.size() - headerBytes;

    auto type = getType(buffer_.data());

    bool const compressible = [&] {
        if (messageBytes <= 70)
            return false;
        switch (type)
        {
            case protocol::mtMANIFESTS:
            case protocol::mtENDPOINTS:
            case protocol::mtTRANSACTION:
            case protocol::mtGET_LEDGER:
            case protocol::mtLEDGER_DATA:
            case protocol::mtGET_OBJECTS:
            case protocol::mtVALIDATORLIST:
                return true;
            case protocol::mtPING:
            case protocol::mtCLUSTER:
            case protocol::mtPROPOSE_LEDGER:
            case protocol::mtSTATUS_CHANGE:
            case protocol::mtHAVE_SET:
            case protocol::mtVALIDATION:
            case protocol::mtGET_SHARD_INFO:
            case protocol::mtSHARD_INFO:
            case protocol::mtGET_PEER_SHARD_INFO:
            case protocol::mtPEER_SHARD_INFO:
                break;
        }
        return false;
    }();

    if (compressible)
    {
        auto payload = static_cast<void const*>(buffer_.data() + headerBytes);

        auto compressedSize = ripple::compression::compress(
            payload,
            messageBytes,
            [&](std::size_t inSize) {  // size of required compressed buffer
                bufferCompressed_.resize(inSize + headerBytesCompressed);
                return (bufferCompressed_.data() + headerBytesCompressed);
            });

        if (compressedSize <
            (messageBytes - (headerBytesCompressed - headerBytes)))
        {
            bufferCompressed_.resize(headerBytesCompressed + compressedSize);
            setHeader(
                bufferCompressed_.data(),
                compressedSize,
                type,
                Algorithm::LZ4,
                messageBytes);
        }
        else
            bufferCompressed_.resize(0);
    }
}

/** Set payload header

    The header is a variable-sized structure that contains information about
    the type of the message and the length and encoding of the payload.

    The first bit determines whether a message is compressed or uncompressed;
    for compressed messages, the next three bits identify the compression
    algorithm.

    All multi-byte values are represented in big endian.

    For uncompressed messages (6 bytes), numbering bits from left to right:

        - The first 6 bits are set to 0.
        - The next 26 bits represent the payload size.
        - The remaining 16 bits represent the message type.

    For compressed messages (10 bytes), numbering bits from left to right:

        - The first 32 bits, together, represent the compression algorithm
          and payload size:
            - The first bit is set to 1 to indicate the message is compressed.
            - The next 3 bits indicate the compression algorithm.
            - The next 2 bits are reserved at this time and set to 0.
            - The remaining 26 bits represent the payload size.
        - The next 16 bits represent the message type.
        - The remaining 32 bits are the uncompressed message size.

    The maximum size of a message at this time is 64 MB. Messages larger than
    this will be dropped and the recipient may, at its option, sever the link.

    @note While nominally a part of the wire protocol, the framing is subject
          to change; future versions of the code may negotiate the use of
          substantially different framing.
*/
void
Message::setHeader(
    std::uint8_t* in,
    std::uint32_t payloadBytes,
    int type,
    Algorithm compression,
    std::uint32_t uncompressedBytes)
{
    auto h = in;

    auto pack = [](std::uint8_t*& in, std::uint32_t size) {
        *in++ = static_cast<std::uint8_t>(
            (size >> 24) & 0x0F);  // leftmost 4 are compression bits
        *in++ = static_cast<std::uint8_t>((size >> 16) & 0xFF);
        *in++ = static_cast<std::uint8_t>((size >> 8) & 0xFF);
        *in++ = static_cast<std::uint8_t>(size & 0xFF);
    };

    pack(in, payloadBytes);

    *in++ = static_cast<std::uint8_t>((type >> 8) & 0xFF);
    *in++ = static_cast<std::uint8_t>(type & 0xFF);

    if (compression != Algorithm::None)
    {
        pack(in, uncompressedBytes);
        *h |= static_cast<std::uint8_t>(compression);
    }
}

std::size_t
Message::getBufferSize()
{
    return buffer_.size();
}

std::vector<uint8_t> const&
Message::getBuffer(Compressed tryCompressed)
{
    if (tryCompressed == Compressed::Off)
        return buffer_;

    std::call_once(once_flag_, &Message::compress, this);

    if (bufferCompressed_.size() > 0)
        return bufferCompressed_;
    else
        return buffer_;
}

int
Message::getType(std::uint8_t const* in) const
{
    int type = (static_cast<int>(*(in + 4)) << 8) + *(in + 5);
    return type;
}

}  // namespace ripple