client.cpp

#include "Utility.h"
#include <curl/curl.h>
#include <sstream>
#include <iostream>
#include <cstdlib>

namespace ThorsAnvil
{
    namespace Socket
    {

class CurlGlobal
{
    public:
        CurlGlobal()
        {
            if (curl_global_init(CURL_GLOBAL_ALL) != 0)
            {
                throw std::runtime_error(buildErrorMessage("CurlGlobal::", __func__, ": curl_global_init: fail"));
            }
        }
        ~CurlGlobal()
        {
            curl_global_cleanup();
        }
};

extern "C" size_t curlConnectorGetData(char *ptr, size_t size, size_t nmemb, void *userdata);

enum RequestType {Get, Head, Put, Post, Delete};
class CurlConnector
{
    CURL*       curl;
    std::string host;
    int         port;
    std::string response;

    friend size_t curlConnectorGetData(char *ptr, size_t size, size_t nmemb, void *userdata);
    std::size_t getData(char *ptr, size_t size)
    {
        response.append(ptr, size);
        return size;
    }
    template<typename Param, typename... Args>
    void curlSetOptionWrapper(CURLoption option, Param parameter, Args... errorMessage)
    {
        CURLcode res;
        if ((res = curl_easy_setopt(curl, option, parameter)) != CURLE_OK)
        {
            throw std::runtime_error(buildErrorMessage(errorMessage..., curl_easy_strerror(res)));
        }
    }


    public:
        CurlConnector(std::string const& host, int port)
            : curl(curl_easy_init( ))
            , host(host)
            , port(port)
        {
            if (curl == nullptr)
            {
                throw std::runtime_error(buildErrorMessage("CurlConnector::", __func__, ": curl_easy_init: fail"));
            }
        }
        CurlConnector(CurlConnector&)               = delete;
        CurlConnector& operator=(CurlConnector&)    = delete;
        CurlConnector(CurlConnector&& rhs) noexcept
            : curl(nullptr)
        {
            rhs.swap(*this);
        }
        CurlConnector& operator=(CurlConnector&& rhs) noexcept
        {
            rhs.swap(*this);
            return *this;
        }
        void swap(CurlConnector& other) noexcept
        {
            using std::swap;
            swap(curl, other.curl);
            swap(host, other.host);
            swap(port, other.port);
            swap(response, other.response);
        }
        ~CurlConnector()
        {
            if (curl)
            {
                curl_easy_cleanup(curl);
            }
        }

        virtual RequestType getRequestType() const = 0;

        void sendMessage(std::string const& urlPath, std::string const& message)
        {
            if (curl == nullptr)
            {
                throw std::logic_error(buildErrorMessage("CurlConnector::", __func__, ": bad  object (this object was moved)"));
            }
            std::stringstream url;
            response.clear();
            url << "http://" << host;
            if (port != 80)
            {
                url << ":" << port;
            }
            url << urlPath;

            CURLcode res;
            auto sListDeleter = [](struct curl_slist* headers){curl_slist_free_all(headers);};
            std::unique_ptr<struct curl_slist, decltype(sListDeleter)> headers(nullptr, sListDeleter);
            headers = std::unique_ptr<struct curl_slist, decltype(sListDeleter)>(curl_slist_append(headers.get(), "Content-Type: text/text"), sListDeleter);

            curlSetOptionWrapper(CURLOPT_HTTPHEADER,        headers.get(),          "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_HTTPHEADER:");
            curlSetOptionWrapper(CURLOPT_ACCEPT_ENCODING,   "*/*",                  "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_ACCEPT_ENCODING:");
            curlSetOptionWrapper(CURLOPT_USERAGENT,         "ThorsCurl-Client/0.1", "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_USERAGENT:");
            curlSetOptionWrapper(CURLOPT_URL,               url.str().c_str(),      "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_URL:");
            curlSetOptionWrapper(CURLOPT_POSTFIELDSIZE,     message.size(),         "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_POSTFIELDSIZE:");
            curlSetOptionWrapper(CURLOPT_COPYPOSTFIELDS,    message.data(),         "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_COPYPOSTFIELDS:");
            curlSetOptionWrapper(CURLOPT_WRITEFUNCTION,     curlConnectorGetData,   "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_WRITEFUNCTION:");
            curlSetOptionWrapper(CURLOPT_WRITEDATA,         this,                   "CurlConnector::", __func__, ": curl_easy_setopt CURLOPT_WRITEDATA:");

            switch(getRequestType())
            {
                case Get:       res = CURLE_OK; /* The default is GET. So do nothing.*/         break;
                case Head:      res = curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "HEAD");    break;
                case Put:       res = curl_easy_setopt(curl, CURLOPT_PUT, 1);                   break;
                case Post:      res = curl_easy_setopt(curl, CURLOPT_POST, 1);                  break;
                case Delete:    res = curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "DELETE");  break;
                default:
                    throw std::domain_error(buildErrorMessage("CurlConnector::", __func__, ": invalid method: ", static_cast<int>(getRequestType())));
            }
            if (res != CURLE_OK)
            {
                throw std::runtime_error(buildErrorMessage("CurlConnector::", __func__, ": curl_easy_setopt CURL_METHOD:", curl_easy_strerror(res)));
            }
            if ((res = curl_easy_perform(curl)) != CURLE_OK)
            {
                throw std::runtime_error(buildErrorMessage("CurlConnector::", __func__, ": curl_easy_perform:", curl_easy_strerror(res)));
            }
        }
        void recvMessage(std::string& message)
        {
            message = std::move(response);
        }
};

class CurlPost: public CurlConnector
{
    public:
        using CurlConnector::CurlConnector;
        virtual RequestType getRequestType() const {return Post;}

};

size_t curlConnectorGetData(char *ptr, size_t size, size_t nmemb, void *userdata)
{
    CurlConnector*  self = reinterpret_cast<CurlConnector*>(userdata);
    return self->getData(ptr, size * nmemb);
}

    }
}

int main(int argc, char* argv[])
{
    namespace Sock = ThorsAnvil::Socket;
    if (argc != 3)
    {
        std::cerr << "Usage: client <host> <Message>\n";
        std::exit(1);
    }

    Sock::CurlGlobal    curlInit;
    Sock::CurlPost      connect(argv[1], 8080);

    connect.sendMessage("/message", argv[2]);

    std::string message;
    connect.recvMessage(message);
    std::cout << message << "\n";
}