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