cpp_json_curl.cc

/*
Demo json + libcurl cpp program
Copyright (C) 2016  Michael Gugino

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

#include <curl/curl.h>
#include <string>
#include <sstream>
#include <iostream>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>

namespace pt = boost::property_tree;
int main(void)
{
    CURL *curl;
    CURLcode res;
    struct curl_slist *list=NULL;
    char *bp;
    size_t size;
    FILE *response_memfile;
    pt::ptree root;
    curl_global_init(CURL_GLOBAL_DEFAULT);
    std::stringstream ss;

    curl = curl_easy_init();
    if(curl) {
        list = curl_slist_append(list, "Accept: application/json");
        if (list == NULL) {
            curl_easy_cleanup(curl);
            curl_global_cleanup();
            return 1;
        }

        response_memfile = open_memstream (&bp, &size);
        if (response_memfile == NULL) {
            curl_easy_cleanup(curl);
            curl_global_cleanup();
            return 1;
        }

        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)response_memfile);
        curl_easy_setopt(curl, CURLOPT_URL, "https://www.foaas.com/linus");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

        #ifdef SKIP_PEER_VERIFICATION
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
        #endif

        #ifdef SKIP_HOSTNAME_VERIFICATION
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
        #endif

        res = curl_easy_perform(curl);
        /* Check for errors */
        if(res != CURLE_OK) {
            std::cout << "curl easy perform failed";
        }
        else {
            fflush(response_memfile);
            // This feels dirty, but I don't have many options considering
            // that curl requires a FILE * object and pt::read_json wants
            // a stream and will not accept a FILE *.
            ss << bp;
            // Load the json file in this ptree
            pt::read_json(ss, root);
            std::cout << root.get<std::string>("message");
        }
        /* cleanup */
        curl_easy_cleanup(curl);
        fclose(response_memfile);
        free(bp);
    }

    curl_global_cleanup();
    return 0;
}