Question

I am trying to write a very simple unix domain datagram client/server.

Here is the python server:

import socket,os

s = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
try:
    os.remove("/tmp/socketname")
except OSError:
    pass
s.bind("/tmp/socketname")
while 1:
    data = s.recv(1024)
    print data

conn.close()

and here is a python client that seems to work just fine with the server

import socket
import time

sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
sock.sendto('Hello, world', "/tmp/socketname")
sock.close()

The purpose of this exercise was to play with boost::asio networking library, the python code just makes the server simple with a simple client to prove(-ish) that the server is working.

I am having some issues with the C++ client:

#include <boost/asio.hpp>

int
main(void)
{
    const pid_t pid = getpid();
    boost::asio::io_service my_service;
    const boost::asio::local::datagram_protocol::endpoint ep("/tmp/socketname");
    boost::asio::local::datagram_protocol::socket my_sock(my_service);

    //my_sock.connect(ep);
    //my_sock.send(boost::asio::buffer(&pid, sizeof(pid)));
    my_sock.send_to(boost::asio::buffer(&pid, sizeof(pid)), ep);

    return 0;
}

If I comment out the 2 lines that use connect/send the seems to work. But the the line which uses send_to fails with the following error.

terminate called after throwing an instance of ‘boost::exception_detail::clone_impl >’
what(): Bad file descriptor
Aborted

Thanks for any and all help provided.

Answer 1

You’ve never opened the socket by calling open(), or any of the other methods that open it automatically, such as connect().

int
main(void)
{
    const pid_t pid = getpid();
    boost::asio::io_service my_service;
    const boost::asio::local::datagram_protocol::endpoint ep("/tmp/socketname");
    boost::asio::local::datagram_protocol::socket my_sock(my_service);

    //my_sock.connect(ep);
    //my_sock.send(boost::asio::buffer(&pid, sizeof(pid)));
    my_sock.open();
    my_sock.send_to(boost::asio::buffer(&pid, sizeof(pid)), ep);

    return 0;
}