HTTP queries

Today I want to show you how to use cURLpp (C++ wrapper around libcURL ) to make a simple HTTP query to ip-api.com in order to retrieve geolocation information of a given host or IP address. I chose cURLpp because it’s simple and easy to use; the example program would not have been any harder using libcURL C API but this is a C++ blog after-all I will be using Boost Property Tree library to deserialize the JSON geo-ip data. All of that is achieved in 15, give or take, lines of actual code… that’s the power of simple and well designed C++ libraries!

The program starts off by setting up aRAII object of type curlpp :: Cleanup which initializes and cleans up cURLpp library. We then create a request object of type curlpp :: Easy and an output std :: stringstream where the received data will be placed. Next we setup some options like verbosity level, URL, port, the output stream, and we execute the query. Finally we parse the JSON data using read_json and iterate over the ptree structure to print it to the console.

geoip.cpp :

#include <iostream>
#include <sstream>
#include <curlpp/cURLpp.hpp>
#include <curlpp/Easy.hpp>
#include <curlpp/Options.hpp>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
 
using namespace std;
 
int main()
{
	try
	{
		curlpp::Cleanup cURLppStartStop;
 
		curlpp::Easy request;
		std::stringstream response;
 
		request.setOpt(curlpp::options::Verbose(true));
		request.setOpt(curlpp::options::WriteStream(&response));
		request.setOpt(curlpp::options::Url("http://ip-api.com/json/vorbrodt.blog"));
		request.setOpt(curlpp::options::Port(80));
 
		request.perform();
 
		boost::property_tree::ptree data;
		boost::property_tree::read_json(response, data);
 
		for(auto& it : data)
			cout << it.first << " = " << it.second.data() << endl;
	}
	catch(exception& e)
	{
		cerr << e.what() << endl;
	}
}