A simple rendezvous protocol implementation to help NAT traversal or hole punching.

The idea is simple, a rendezvous server to observe peers address and forward connection request. When seen both peers sent each other packet, the NAT device or firewall rule then allow the traffic through.

client1

use rndz::tcp::Client;

let c1 = Client::new(rndz_server_addr, "c1", None)?;
c1.listen()?;
while let Ok(stream) = c1.accept()?{
//...
}

client2

use rndz::tcp::Client;
let c2 = Client::new(rndz_server_addr, "c2", None)?;
let stream = c.connect("c1")?;

client1

use rndz::udp::Client;

let c1 = Client::new(rndz_server_addr, "c1", None)?;
c1.listen()?;
c1.as_socket().recv_from(...)?;

client2

use rndz::udp::Client;
let c2 = Client::new(rndz_server_addr, "c2", None)?;
c.connect("c1")?;
c.as_socket().send(b'hello')?;

rndz server

$ rndz server --listen-addr 0.0.0.0:8888    //if you want client communicate with ipv6, use [::]:8888

client1

$ rndz client --id c1 --server-addr rndz_server:8888 

client2

$ rndz client --id c2 --server-addr rndz_server:8888 --remote-peer c1

Because it rely on socket option SO_REUSEADDR and SO_REUSEPORT behavior, and connected UDP socket, it doesn't not work on all platform.

Test pass on linux; udp::Client::listen() not works on windows..

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