Renamed GdbRsp directory to Gdb
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269
src/DebugServer/Gdb/Connection.cpp
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269
src/DebugServer/Gdb/Connection.cpp
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#include "Connection.hpp"
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#include <arpa/inet.h>
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#include <sys/epoll.h>
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#include <cerrno>
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#include <fcntl.h>
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#include "Exceptions/ClientDisconnected.hpp"
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#include "Exceptions/ClientCommunicationError.hpp"
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#include "src/Exceptions/Exception.hpp"
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#include "src/Exceptions/DebugServerInterrupted.hpp"
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#include "src/Logger/Logger.hpp"
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namespace Bloom::DebugServer::Gdb
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{
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using namespace Exceptions;
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using namespace Bloom::Exceptions;
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using ResponsePackets::ResponsePacket;
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Connection::Connection(int serverSocketFileDescriptor, EventNotifier& interruptEventNotifier)
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: interruptEventNotifier(interruptEventNotifier)
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{
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this->accept(serverSocketFileDescriptor);
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::fcntl(
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this->socketFileDescriptor.value(),
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F_SETFL,
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::fcntl(this->socketFileDescriptor.value(), F_GETFL, 0) | O_NONBLOCK
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);
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this->epollInstance.addEntry(
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this->socketFileDescriptor.value(),
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static_cast<std::uint16_t>(EpollEvent::READ_READY)
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);
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this->enableReadInterrupts();
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}
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Connection::~Connection() {
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this->close();
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}
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std::string Connection::getIpAddress() const {
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std::array<char, INET_ADDRSTRLEN> ipAddress = {};
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if (::inet_ntop(AF_INET, &(socketAddress.sin_addr), ipAddress.data(), INET_ADDRSTRLEN) == nullptr) {
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throw Exception("Failed to convert client IP address to text form.");
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}
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return std::string(ipAddress.data());
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}
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std::vector<RawPacketType> Connection::readRawPackets() {
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std::vector<RawPacketType> output;
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const auto bytes = this->read();
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std::size_t bufferSize = bytes.size();
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for (std::size_t byteIndex = 0; byteIndex < bufferSize; byteIndex++) {
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auto byte = bytes[byteIndex];
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if (byte == 0x03) {
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/*
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* This is an interrupt packet - it doesn't carry any of the usual packet frame bytes, so we'll just
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* add them here, in order to keep things consistent.
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*
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* Because we're effectively faking the packet frame, we can use any value for the checksum.
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*/
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output.push_back({'$', byte, '#', 'F', 'F'});
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} else if (byte == '$') {
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// Beginning of packet
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RawPacketType rawPacket;
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rawPacket.push_back('$');
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auto packetIndex = byteIndex;
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bool validPacket = false;
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bool isByteEscaped = false;
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for (packetIndex++; packetIndex < bufferSize; packetIndex++) {
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byte = bytes[packetIndex];
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if (byte == '}' && !isByteEscaped) {
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isByteEscaped = true;
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continue;
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}
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if (!isByteEscaped) {
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if (byte == '$') {
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// Unexpected end of packet
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validPacket = false;
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break;
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}
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if (byte == '#') {
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// End of packet data
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if ((bufferSize - 1) < (packetIndex + 2)) {
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// There should be at least two more bytes in the buffer, for the checksum.
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break;
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}
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rawPacket.push_back(byte);
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// Add the checksum bytes and break the loop
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rawPacket.push_back(bytes[++packetIndex]);
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rawPacket.push_back(bytes[++packetIndex]);
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validPacket = true;
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break;
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}
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} else {
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// Escaped bytes are XOR'd with a 0x20 mask.
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byte ^= 0x20;
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isByteEscaped = false;
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}
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rawPacket.push_back(byte);
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}
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if (validPacket) {
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// Acknowledge receipt
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this->write({'+'});
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output.push_back(rawPacket);
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byteIndex = packetIndex;
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}
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}
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}
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return output;
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}
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void Connection::writePacket(const ResponsePacket& packet) {
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// Write the packet repeatedly until the GDB client acknowledges it.
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int attempts = 0;
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auto rawPacket = packet.toRawPacket();
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do {
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if (attempts > 10) {
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throw ClientCommunicationError("Failed to write GDB response packet - client failed to "
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"acknowledge receipt - retry limit reached");
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}
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this->write(rawPacket);
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attempts++;
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} while (this->readSingleByte(false).value_or(0) != '+');
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}
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void Connection::accept(int serverSocketFileDescriptor) {
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int socketAddressLength = sizeof(this->socketAddress);
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const auto socketFileDescriptor = ::accept(
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serverSocketFileDescriptor,
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reinterpret_cast<sockaddr*>(&(this->socketAddress)),
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reinterpret_cast<socklen_t*>(&socketAddressLength)
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);
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if (socketFileDescriptor < 0) {
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throw Exception("Failed to accept GDB Remote Serial Protocol connection");
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}
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this->socketFileDescriptor = socketFileDescriptor;
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}
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void Connection::close() noexcept {
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if (this->socketFileDescriptor.value_or(-1) >= 0) {
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::close(this->socketFileDescriptor.value());
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this->socketFileDescriptor = std::nullopt;
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}
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}
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std::vector<unsigned char> Connection::read(
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size_t bytes,
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bool interruptible,
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std::optional<std::chrono::milliseconds> timeout
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) {
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auto output = std::vector<unsigned char>();
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constexpr size_t bufferSize = 1024;
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std::array<unsigned char, bufferSize> buffer = {};
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ssize_t bytesRead = 0;
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if (interruptible) {
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if (this->readInterruptEnabled != interruptible) {
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this->enableReadInterrupts();
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} else {
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// Clear any previous interrupts that are still hanging around
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this->interruptEventNotifier.clear();
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}
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}
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if (this->readInterruptEnabled != interruptible && !interruptible) {
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this->disableReadInterrupts();
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}
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const auto eventFileDescriptor = this->epollInstance.waitForEvent(timeout);
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if (
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!eventFileDescriptor.has_value()
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|| eventFileDescriptor.value() == this->interruptEventNotifier.getFileDescriptor()
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) {
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// Interrupted
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this->interruptEventNotifier.clear();
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throw DebugServerInterrupted();
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}
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size_t bytesToRead = (bytes > bufferSize || bytes == 0) ? bufferSize : bytes;
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while (
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bytesToRead > 0
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&& (bytesRead = ::read(this->socketFileDescriptor.value(), buffer.data(), bytesToRead)) > 0
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) {
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output.insert(output.end(), buffer.begin(), buffer.begin() + bytesRead);
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if (bytesRead < bytesToRead) {
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// No more data available
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break;
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}
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bytesToRead = ((bytes - output.size()) > bufferSize || bytes == 0) ? bufferSize : (bytes - output.size());
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}
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if (output.empty()) {
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// EOF means the client has disconnected
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throw ClientDisconnected();
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}
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return output;
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}
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std::optional<unsigned char> Connection::readSingleByte(bool interruptible) {
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auto bytes = this->read(1, interruptible, std::chrono::milliseconds(300));
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if (!bytes.empty()) {
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return bytes.front();
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}
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return std::nullopt;
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}
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void Connection::write(const std::vector<unsigned char>& buffer) {
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Logger::debug("Writing packet: " + std::string(buffer.begin(), buffer.end()));
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if (::write(this->socketFileDescriptor.value(), buffer.data(), buffer.size()) == -1) {
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if (errno == EPIPE || errno == ECONNRESET) {
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// Connection was closed
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throw ClientDisconnected();
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}
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throw ClientCommunicationError("Failed to write " + std::to_string(buffer.size())
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+ " bytes to GDP client socket - error no: "
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+ std::to_string(errno));
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}
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}
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void Connection::disableReadInterrupts() {
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this->epollInstance.removeEntry(this->interruptEventNotifier.getFileDescriptor());
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this->readInterruptEnabled = false;
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}
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void Connection::enableReadInterrupts() {
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this->epollInstance.addEntry(
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this->interruptEventNotifier.getFileDescriptor(),
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static_cast<std::uint16_t>(EpollEvent::READ_READY)
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);
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this->readInterruptEnabled = true;
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}
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}
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