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use std::net::{
Ipv4Addr, Ipv6Addr, SocketAddrV4, SocketAddrV6, TcpListener, ToSocketAddrs, UdpSocket,
};
use rand::prelude::*;
pub type Port = u16;
fn test_bind_udp<A: ToSocketAddrs>(addr: A) -> Option<Port> {
Some(UdpSocket::bind(addr).ok()?.local_addr().ok()?.port())
}
fn test_bind_tcp<A: ToSocketAddrs>(addr: A) -> Option<Port> {
Some(TcpListener::bind(addr).ok()?.local_addr().ok()?.port())
}
pub fn is_free_udp(port: Port) -> bool {
let ipv4 = SocketAddrV4::new(Ipv4Addr::LOCALHOST, port);
let ipv6 = SocketAddrV6::new(Ipv6Addr::LOCALHOST, port, 0, 0);
test_bind_udp(ipv6).is_some() && test_bind_udp(ipv4).is_some()
}
pub fn is_free_tcp(port: Port) -> bool {
let ipv4 = SocketAddrV4::new(Ipv4Addr::LOCALHOST, port);
let ipv6 = SocketAddrV6::new(Ipv6Addr::LOCALHOST, port, 0, 0);
test_bind_tcp(ipv6).is_some() && test_bind_tcp(ipv4).is_some()
}
pub fn is_free(port: Port) -> bool {
is_free_tcp(port) && is_free_udp(port)
}
fn ask_free_tcp_port() -> Option<Port> {
let ipv4 = SocketAddrV4::new(Ipv4Addr::LOCALHOST, 0);
let ipv6 = SocketAddrV6::new(Ipv6Addr::LOCALHOST, 0, 0, 0);
test_bind_tcp(ipv6).or_else(|| test_bind_tcp(ipv4))
}
pub fn pick_unused_port() -> Option<Port> {
let mut rng = rand::thread_rng();
for _ in 0..10 {
let port = rng.gen_range(15000, 25000);
if is_free(port) {
return Some(port);
}
}
for _ in 0..10 {
if let Some(port) = ask_free_tcp_port() {
if is_free_udp(port) {
return Some(port);
}
}
}
None
}
#[cfg(test)]
mod tests {
use super::pick_unused_port;
#[test]
fn it_works() {
assert!(pick_unused_port().is_some());
}
}