| // Copyright 2020 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| use std::net::{Ipv4Addr, Ipv6Addr, SocketAddrV4, SocketAddrV6, TcpListener, ToSocketAddrs}; |
| |
| pub type Port = u16; |
| |
| /// Asks the OS for a free port |
| fn ask_free_tcp_port() -> Option<Port> { |
| let ipv4 = SocketAddrV4::new(Ipv4Addr::LOCALHOST, 0); |
| let ipv6 = SocketAddrV6::new(Ipv6Addr::LOCALHOST, 0, 0, 0); |
| bind_tcp(ipv6).or_else(|| bind_tcp(ipv4)) |
| } |
| |
| // Try to bind to a socket using TCP |
| fn bind_tcp<A: ToSocketAddrs>(addr: A) -> Option<Port> { |
| match TcpListener::bind(addr).map(|s| s.local_addr().map(|a| a.port())) { |
| Ok(port) => port.ok(), |
| Err(_) => None, |
| } |
| } |
| |
| /// Picks an available tcp port |
| pub fn pick_unused_port() -> Option<Port> { |
| for _ in 0..10 { |
| if let Some(port) = ask_free_tcp_port() { |
| return Some(port); |
| } |
| } |
| None |
| } |
