tcp_client-windows.h

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// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#define WIN32_LEAN_AND_MEAN
// tcp client helper
#include <spdlog/common.h>
#include <spdlog/details/os.h>
 
#include <winsock2.h>
#include <windows.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
#include <string>
 
#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "Mswsock.lib")
#pragma comment(lib, "AdvApi32.lib")
 
namespace spdlog {
namespace details {
class tcp_client
{
    SOCKET socket_ = INVALID_SOCKET;
 
    static bool winsock_initialized_()
    {
        SOCKET s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (s == INVALID_SOCKET)
        {
            return false;
        }
        else
        {
            closesocket(s);
            return true;
        }
    }
 
    static void init_winsock_()
    {
        WSADATA wsaData;
        auto rv = WSAStartup(MAKEWORD(2, 2), &wsaData);
        if (rv != 0)
        {
            throw_winsock_error_("WSAStartup failed", ::WSAGetLastError());
        }
    }
 
    static void throw_winsock_error_(const std::string &msg, int last_error)
    {
        char buf[512];
        ::FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, last_error,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), buf, (sizeof(buf) / sizeof(char)), NULL);
 
        throw_spdlog_ex(fmt::format("tcp_sink - {}: {}", msg, buf));
    }
 
public:
    bool is_connected() const
    {
        return socket_ != INVALID_SOCKET;
    }
 
    void close()
    {
        ::closesocket(socket_);
        socket_ = INVALID_SOCKET;
        WSACleanup();
    }
 
    SOCKET fd() const
    {
        return socket_;
    }
 
    ~tcp_client()
    {
        close();
    }
 
    // try to connect or throw on failure
    void connect(const std::string &host, int port)
    {
        // initialize winsock if needed
        if (!winsock_initialized_())
        {
            init_winsock_();
        }
 
        if (is_connected())
        {
            close();
        }
        struct addrinfo hints
        {};
        ZeroMemory(&hints, sizeof(hints));
 
        hints.ai_family = AF_INET;       // IPv4
        hints.ai_socktype = SOCK_STREAM; // TCP
        hints.ai_flags = AI_NUMERICSERV; // port passed as as numeric value
        hints.ai_protocol = 0;
 
        auto port_str = std::to_string(port);
        struct addrinfo *addrinfo_result;
        auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
        int last_error = 0;
        if (rv != 0)
        {
            last_error = ::WSAGetLastError();
            WSACleanup();
            throw_winsock_error_("getaddrinfo failed", last_error);
        }
 
        // Try each address until we successfully connect(2).
 
        for (auto *rp = addrinfo_result; rp != nullptr; rp = rp->ai_next)
        {
            socket_ = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
            if (socket_ == INVALID_SOCKET)
            {
                last_error = ::WSAGetLastError();
                WSACleanup();
                continue;
            }
            if (::connect(socket_, rp->ai_addr, (int)rp->ai_addrlen) == 0)
            {
                break;
            }
            else
            {
                last_error = ::WSAGetLastError();
                close();
            }
        }
        ::freeaddrinfo(addrinfo_result);
        if (socket_ == INVALID_SOCKET)
        {
            WSACleanup();
            throw_winsock_error_("connect failed", last_error);
        }
 
        // set TCP_NODELAY
        int enable_flag = 1;
        ::setsockopt(socket_, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char *>(&enable_flag), sizeof(enable_flag));
    }
 
    // Send exactly n_bytes of the given data.
    // On error close the connection and throw.
    void send(const char *data, size_t n_bytes)
    {
        size_t bytes_sent = 0;
        while (bytes_sent < n_bytes)
        {
            const int send_flags = 0;
            auto write_result = ::send(socket_, data + bytes_sent, (int)(n_bytes - bytes_sent), send_flags);
            if (write_result == SOCKET_ERROR)
            {
                int last_error = ::WSAGetLastError();
                close();
                throw_winsock_error_("send failed", last_error);
            }
 
            if (write_result == 0) // (probably should not happen but in any case..)
            {
                break;
            }
            bytes_sent += static_cast<size_t>(write_result);
        }
    }
};
} // namespace details
} // namespace spdlog