proxmox-async: add udp::connect() helper

so that we do not have to always check the target ipaddr family manually

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-async/Cargo.toml

@@ -17,7 +17,7 @@ flate2 = "1.0"
 futures = "0.3"
 lazy_static = "1.4"
 pin-utils = "0.1.0"
-tokio = { version = "1.0", features = ["fs", "rt", "rt-multi-thread", "sync"] }
+tokio = { version = "1.0", features = ["fs", "net", "rt", "rt-multi-thread", "sync"] }
 walkdir = "2"
 
 proxmox-sys = { path = "../proxmox-sys", version = "0.2.0" }

proxmox-async/src/io/mod.rs

@@ -2,3 +2,5 @@
 
 mod async_channel_writer;
 pub use async_channel_writer::AsyncChannelWriter;
+
+pub mod udp;

proxmox-async/src/io/udp.rs

@@ -0,0 +1,36 @@
+use std::io;
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr};
+
+use tokio::net::{ToSocketAddrs, UdpSocket};
+
+/// Helper to connect to UDP addresses without having to manually bind to the correct ip address
+pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<UdpSocket> {
+    let mut last_err = None;
+    for address in tokio::net::lookup_host(&addr).await? {
+        let bind_address = match address {
+            SocketAddr::V4(_) => SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 0),
+            SocketAddr::V6(_) => SocketAddr::new(Ipv6Addr::UNSPECIFIED.into(), 0),
+        };
+        let socket = match UdpSocket::bind(bind_address).await {
+            Ok(sock) => sock,
+            Err(err) => {
+                last_err = Some(err);
+                continue;
+            }
+        };
+        match socket.connect(address).await {
+            Ok(()) => return Ok(socket),
+            Err(err) => {
+                last_err = Some(err);
+                continue;
+            }
+        }
+    }
+
+    Err(last_err.unwrap_or_else(|| {
+        io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "could not resolve to any addresses",
+        )
+    }))
+}