How to build an echo server and client using asio local datagram?

Question

// server

#include <boost/asio.hpp>

int main()
{
    ::unlink("local_socket");
    boost::asio::io_service io_service;
    boost::asio::local::datagram_protocol::endpoint endpoint("local_socket");
    boost::asio::local::datagram_protocol::socket socket(io_service, endpoint);

    char recv_buf[1024];
    while (1)
    {
        boost::asio::local::datagram_protocol::endpoint senderEndpoint;
        size_t len = socket.receive_from(
            boost::asio::buffer(recv_buf, 1024), senderEndpoint);
        printf("***%s###\n", senderEndpoint.path().c_str());

        socket.send_to(
            boost::asio::buffer(recv_buf, len), senderEndpoint);
    }

    return 0;
}

// client

#include <boost/asio.hpp>

enum { max_length = 1024 };

int main(int argc, char* argv[])
{
    boost::asio::io_service io_service;
    boost::asio::local::datagram_protocol::endpoint endpoint("local_socket");
    boost::asio::local::datagram_protocol::socket socket(io_service);
    socket.open();

    std::cout << "Enter message: ";
    char request[max_length];
    std::cin.getline(request, max_length);
    size_t request_length = strlen(request);

    socket.send_to(
        boost::asio::buffer(request, request_length), endpoint);

    char reply[max_length];
    size_t reply_length = socket.receive_from(
        boost::asio::buffer(reply, max_length), endpoint);

    std::cout << "Reply is: ";
    std::cout.write(reply, reply_length);
    std::cout << "\n";

    return 0;
}

When I use client to send "123", and server is coredump with:

***### terminate called after throwing an instance of 'boost::exception_detail::clone_impl

' what(): send_to: Invalid argument Aborted

Answer 1

Find the answer here. client,server.

Answer 2

The reason the server aborting is because the senderEndpoint is not being populated by the call to receive_from - the client socket is not bound to anything so it does not send a file descriptor on which to receive responses. If we refactor the client like this:

#include <iostream>

#include <boost/asio.hpp>

enum { max_length = 1024 };

int main(int argc, char* argv[])
{
    boost::asio::io_service io_service;
    boost::asio::local::datagram_protocol::endpoint server_endpoint("local_socket");
    // Create client endpoint on which to receive response
    std::string client_addr = "local_socket.";
    client_addr += std::to_string(::getpid());
    ::unlink(client_addr.c_str());
    boost::asio::local::datagram_protocol::endpoint client_endpoint(client_addr.c_str());
    boost::asio::local::datagram_protocol::socket socket(io_service, client_endpoint);

    std::cout << "Enter message: ";
    char request[max_length];
    std::cin.getline(request, max_length);
    size_t request_length = strlen(request);

    socket.send_to(
        boost::asio::buffer(request, request_length), server_endpoint);

    char reply[max_length];
    size_t reply_length = socket.receive_from(
        boost::asio::buffer(reply, max_length), client_endpoint);

    std::cout << "Reply is: ";
    std::cout.write(reply, reply_length);
    std::cout << "\n";

    return 0;
}

then it works as expected:

Enter message: 123
***local_socket.29635###
Reply is: 123