"Can't assign requested address" when sending to a UdpSocket

Question

let addr = "239.255.255.250:1982";
let socket = UdpSocket::bind(addr).unwrap();
let message = "some message".as_bytes();
socket.send_to(message, addr).unwrap();

This code gives the following error for the last line:

Error { repr: Os { code: 49, message: "Can\'t assign requested address" } }

Why would that be the case?

EDIT: I tried the following as suggested:

let addr = "239.255.255.250:1982";
let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
let message = "some message".as_bytes();
socket.send_to(message, addr).unwrap();

But that didn't change anything, unfortunately.

Answer 1

The address you used to bind your UdpSocket to is a multicast address.

The argument to UdpSocket::bind should be the local address you send from.

The docs use 127.0.0.1:34254. If it is not currently being used, this should work for you. Additionally you can give it an array of potential adresses to use.