Function CaptureMessageToFile

src/net.cpp:4270–4304

Dump binary message to file, with timestamp.

// Dump binary message to file, with timestamp.
static void CaptureMessageToFile(const CAddress& addr,
                                 const std::string& msg_type,
                                 std::span<const unsigned char> data,
                                 bool is_incoming)
{
    // Note: This function captures the message at the time of processing,
    // not at socket receive/send time.
    // This ensures that the messages are always in order from an application
    // layer (processing) perspective.
    auto now = GetTime<std::chrono::microseconds>();

    // Windows folder names cannot include a colon
    std::string clean_addr = addr.ToStringAddrPort();
    std::replace(clean_addr.begin(), clean_addr.end(), ':', '_');

    fs::path base_path = gArgs.GetDataDirNet() / "message_capture" / fs::u8path(clean_addr);
    fs::create_directories(base_path);

    fs::path path = base_path / (is_incoming ? "msgs_recv.dat" : "msgs_sent.dat");
    AutoFile f{fsbridge::fopen(path, "ab")};

    ser_writedata64(f, now.count());
    f << std::span{msg_type};
    for (auto i = msg_type.length(); i < CMessageHeader::MESSAGE_TYPE_SIZE; ++i) {
        f << uint8_t{'\0'};
    }
    uint32_t size = data.size();
    ser_writedata32(f, size);
    f << data;

    if (f.fclose() != 0) {
        throw std::ios_base::failure(
            strprintf("Error closing %s after write, file contents are likely incomplete", fs::PathToString(path)));
    }
}

std::function<void(const CAddress& addr,
                   const std::string& msg_type,