Temporarily fix hostname resolving

..by preferably returning IPv4 address

common/src/network/client_webtransport.rs

@@ -4,7 +4,7 @@ use bevy::prelude::*;
 use lightyear::prelude::client::*;
 use lightyear::prelude::*;
 
-use thiserror::Error;
+use crate::network::DEFAULT_PORT;
 
 pub struct ConnectWebTransportCommand {
     server_addr: SocketAddr,
@@ -13,9 +13,8 @@ pub struct ConnectWebTransportCommand {
 
 impl ConnectWebTransportCommand {
     pub fn new(server_addr: &str, certificate_digest: String) -> Result<Self> {
-        let server_addr = to_socket_addr_with_default_port(server_addr, super::DEFAULT_PORT)?;
         Ok(Self {
-            server_addr,
+            server_addr: resolve_addr(&server_addr, DEFAULT_PORT)?,
             certificate_digest,
         })
     }
@@ -41,23 +40,31 @@ impl Command for ConnectWebTransportCommand {
 
 // TODO: Move this to its own `utils` module?
 // FIXME: Hostname resolving does not work on web.
-fn to_socket_addr_with_default_port(addr: &str, default_port: u16) -> Result<SocketAddr> {
+fn resolve_addr(addr: &str, default_port: u16) -> Result<SocketAddr> {
-    let has_port = match (addr.rfind(']'), addr.rfind(':')) {
+    let addr = with_default_port(addr, default_port);
+    let socket_addrs = addr.to_socket_addrs()?.collect::<Vec<_>>();
+    if let Some(ipv4) = socket_addrs.iter().find(|a| a.is_ipv4()) {
+        Ok(*ipv4) // Prefer first IPv4 address found..
+    } else if let Some(ipv6) = socket_addrs.first() {
+        Ok(*ipv6) // ..otherwise fallback to IPv6.
+    } else {
+        Err(std::io::Error::other("hostname could not be resolved").into())
+    }
+}
+
+fn with_default_port(addr: &str, default_port: u16) -> String {
+    if is_port_specified(addr) {
+        addr.to_string()
+    } else {
+        format!("{addr}:{default_port}")
+    }
+}
+
+fn is_port_specified(addr: &str) -> bool {
+    match (addr.rfind(']'), addr.rfind(':')) {
         // This doesn't match colons within IPv6 brackets, like `[::1]`.
         (Some(bracket), Some(colon)) if bracket < colon => true,
         (None, Some(_)) => true,
         _ => false,
-    };
+    }
-
-    let mut socket_addrs = if has_port {
-        addr.to_socket_addrs()
-    } else {
-        (addr, default_port).to_socket_addrs()
-    }?;
-
-    socket_addrs.next().ok_or(ResolveError.into())
 }
-
-#[derive(Error, Debug)]
-#[error("hostname could not be resolved to any address")]
-pub struct ResolveError;