Segmentation fault using Boost Asio reference

Question

The link I'm using for the asio code is https://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/tutorial/tutdaytime1.html

#include <iostream>
#include <boost/asio.hpp>
#include <boost/array.hpp>
// #include <src.hpp>

using boost::asio::ip::tcp;

int main(int argc, char *argv[])
{
    std::cout << "Started" << std::endl;

    try{

        boost::asio::io_context io;

        boost::asio::steady_timer t(io, boost::asio::chrono::seconds(5));

        tcp::resolver resolver(io);
        tcp::resolver::results_type endpoints = resolver.resolve(argv[1],"daytime");

        tcp::socket socket(io);
        boost::asio::connect(socket,endpoints);

        boost::array<char,128> buf;
        boost::system::error_code error;

        size_t len = socket.read_some(boost::asio::buffer(buf), error);

        if (error == boost::asio::error::eof)
        {
            std::cout << "No Errors" << std::endl;
        }
        else if(error){
            throw boost::system::system_error(error);
        }

        std::cout << "Data is: ";
        std::cout.write(buf.data(), len);

        io.run();
    }
    catch(std::exception& e){
        std::cerr << e.what() << std::endl;
    }

    return 0;
}

I get a segmentation fault trying to run code for a daytime tcp client and I don't have any idea why. It says the buffer function auto prevents buffer overflows on the reference. I just need it to not give me a segmentation fault, I'm not experienced with either c++ or networking.

Answer 1

Likely segfaulting because you're using command line arguments not passed?

Either hard code the argument:

    tcp::resolver::results_type endpoints = resolver.resolve("127.0.0.1", "daytime");

Or instead, check that arguments are present:

if (argc < 2) {
    std::cerr << "Usage: " << argv[0] << " HOSTNAME" << std::endl;
    return 1;
}