lighthouse/common/unused_port/src/lib.rs
Paul Hauner 0a6a8ea3b0 Engine API v1.0.0.alpha.6 + interop tests (#3024)
## Issue Addressed

NA

## Proposed Changes

This PR extends #3018 to address my review comments there and add automated integration tests with Geth (and other implementations, in the future).

I've also de-duplicated the "unused port" logic by creating an  `common/unused_port` crate.

## Additional Info

I'm not sure if we want to merge this PR, or update #3018 and merge that. I don't mind, I'm primarily opening this PR to make sure CI works.


Co-authored-by: Mark Mackey <mark@sigmaprime.io>
2022-02-17 21:47:06 +00:00

56 lines
1.9 KiB
Rust

use std::net::{TcpListener, UdpSocket};
#[derive(Copy, Clone)]
pub enum Transport {
Tcp,
Udp,
}
/// A convenience function for `unused_port(Transport::Tcp)`.
pub fn unused_tcp_port() -> Result<u16, String> {
unused_port(Transport::Tcp)
}
/// A convenience function for `unused_port(Transport::Tcp)`.
pub fn unused_udp_port() -> Result<u16, String> {
unused_port(Transport::Udp)
}
/// A bit of hack to find an unused port.
///
/// Does not guarantee that the given port is unused after the function exits, just that it was
/// unused before the function started (i.e., it does not reserve a port).
///
/// ## Notes
///
/// It is possible that users are unable to bind to the ports returned by this function as the OS
/// has a buffer period where it doesn't allow binding to the same port even after the socket is
/// closed. We might have to use SO_REUSEADDR socket option from `std::net2` crate in that case.
pub fn unused_port(transport: Transport) -> Result<u16, String> {
let local_addr = match transport {
Transport::Tcp => {
let listener = TcpListener::bind("127.0.0.1:0").map_err(|e| {
format!("Failed to create TCP listener to find unused port: {:?}", e)
})?;
listener.local_addr().map_err(|e| {
format!(
"Failed to read TCP listener local_addr to find unused port: {:?}",
e
)
})?
}
Transport::Udp => {
let socket = UdpSocket::bind("127.0.0.1:0")
.map_err(|e| format!("Failed to create UDP socket to find unused port: {:?}", e))?;
socket.local_addr().map_err(|e| {
format!(
"Failed to read UDP socket local_addr to find unused port: {:?}",
e
)
})?
}
};
Ok(local_addr.port())
}