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// *****************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
// *****************************************************************************
#ifndef SOCKET_H_23498325972583947678456437
#define SOCKET_H_23498325972583947678456437
#include "sys_error.h"
#include <unistd.h> //close
#include <sys/socket.h>
#include <netdb.h> //getaddrinfo
namespace zen
{
#define THROW_LAST_SYS_ERROR_WSA(functionName) \
do { const ErrorCode ecInternal = getLastError(); throw SysError(formatSystemError(functionName, ecInternal)); } while (false)
//patch up socket portability:
using SocketType = int;
const SocketType invalidSocket = -1;
inline void closeSocket(SocketType s) { ::close(s); }
warn_static("log on error!")
//Winsock needs to be initialized before calling any of these functions! (WSAStartup/WSACleanup)
class Socket //throw SysError
{
public:
Socket(const Zstring& server, const Zstring& serviceName) //throw SysError
{
const addrinfo hints
{
.ai_flags = AI_ADDRCONFIG, //save a AAAA lookup on machines that can't use the returned data anyhow
.ai_socktype = SOCK_STREAM, //we *do* care about this one!
};
addrinfo* servinfo = nullptr;
ZEN_ON_SCOPE_EXIT(if (servinfo) ::freeaddrinfo(servinfo));
const int rcGai = ::getaddrinfo(server.c_str(), serviceName.c_str(), &hints, &servinfo);
if (rcGai != 0)
throw SysError(formatSystemError("getaddrinfo", replaceCpy(_("Error code %x"), L"%x", numberTo<std::wstring>(rcGai)), utfTo<std::wstring>(::gai_strerror(rcGai))));
if (!servinfo)
throw SysError(formatSystemError("getaddrinfo", L"", L"Empty server info."));
const auto getConnectedSocket = [](const auto& /*::addrinfo*/ ai)
{
SocketType testSocket = ::socket(ai.ai_family, //int socket_family
SOCK_CLOEXEC |
ai.ai_socktype, //int socket_type
ai.ai_protocol); //int protocol
if (testSocket == invalidSocket)
THROW_LAST_SYS_ERROR_WSA("socket");
ZEN_ON_SCOPE_FAIL(closeSocket(testSocket));
warn_static("support timeout! https://stackoverflow.com/questions/2597608/c-socket-connection-timeout")
if (::connect(testSocket, ai.ai_addr, static_cast<int>(ai.ai_addrlen)) != 0)
THROW_LAST_SYS_ERROR_WSA("connect");
return testSocket;
};
std::optional<SysError> firstError;
for (const auto* /*::addrinfo*/ si = servinfo; si; si = si->ai_next)
try
{
socket_ = getConnectedSocket(*si); //throw SysError; pass ownership
return;
}
catch (const SysError& e) { if (!firstError) firstError = e; }
throw* firstError; //list was not empty, so there must have been an error!
}
~Socket() { closeSocket(socket_); }
SocketType get() const { return socket_; }
private:
Socket (const Socket&) = delete;
Socket& operator=(const Socket&) = delete;
SocketType socket_ = invalidSocket;
};
//more socket helper functions:
namespace
{
size_t tryReadSocket(SocketType socket, void* buffer, size_t bytesToRead) //throw SysError; may return short, only 0 means EOF!
{
if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
int bytesReceived = 0;
for (;;)
{
bytesReceived = ::recv(socket, //_In_ SOCKET s
static_cast<char*>(buffer), //_Out_ char* buf
static_cast<int>(bytesToRead), //_In_ int len
0); //_In_ int flags
if (bytesReceived >= 0 || errno != EINTR)
break;
}
if (bytesReceived < 0)
THROW_LAST_SYS_ERROR_WSA("recv");
if (static_cast<size_t>(bytesReceived) > bytesToRead) //better safe than sorry
throw SysError(formatSystemError("recv", L"", L"Buffer overflow."));
return bytesReceived; //"zero indicates end of file"
}
size_t tryWriteSocket(SocketType socket, const void* buffer, size_t bytesToWrite) //throw SysError; may return short! CONTRACT: bytesToWrite > 0
{
if (bytesToWrite == 0)
throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
int bytesWritten = 0;
for (;;)
{
bytesWritten = ::send(socket, //_In_ SOCKET s
static_cast<const char*>(buffer), //_In_ const char* buf
static_cast<int>(bytesToWrite), //_In_ int len
0); //_In_ int flags
if (bytesWritten >= 0 || errno != EINTR)
break;
}
if (bytesWritten < 0)
THROW_LAST_SYS_ERROR_WSA("send");
if (bytesWritten > static_cast<int>(bytesToWrite))
throw SysError(formatSystemError("send", L"", L"Buffer overflow."));
if (bytesWritten == 0)
throw SysError(formatSystemError("send", L"", L"Zero bytes processed."));
return bytesWritten;
}
}
//initiate termination of connection by sending TCP FIN package
inline
void shutdownSocketSend(SocketType socket) //throw SysError
{
if (::shutdown(socket, SHUT_WR) != 0)
THROW_LAST_SYS_ERROR_WSA("shutdown");
}
}
#endif //SOCKET_H_23498325972583947678456437
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