udp: add network.only_ipv6 config flag

TODO.md

@@ -20,12 +20,10 @@
   * uring
     * ValidUntil periodic update
     * statistics
-    * ipv6_only
     * shared config keys such as poll interval
   * mio
     * stagger connection cleaning intervals?
     * ipv4-mapped addresses
-    * ipv6_only
   * glommio
     * consider sending local responses immediately
     * consider adding ConnectedScrapeRequest::Scrape(PendingScrapeRequest)

aquatic_udp/src/lib/common/network.rs

@@ -123,6 +123,10 @@ pub fn create_socket(config: &Config) -> ::std::net::UdpSocket {
     }
     .expect("create socket");
 
+    if config.network.only_ipv6 {
+        socket.set_only_v6(true).expect("socket: set only ipv6");
+    }
+
     socket.set_reuse_port(true).expect("socket: set reuse port");
 
     socket

aquatic_udp/src/lib/config.rs

@@ -38,6 +38,7 @@ impl aquatic_cli_helpers::Config for Config {
 pub struct NetworkConfig {
     /// Bind to this address
     pub address: SocketAddr,
+    pub only_ipv6: bool,
     /// Size of socket recv buffer. Use 0 for OS default.
     ///
     /// This setting can have a big impact on dropped packages. It might
@@ -120,6 +121,7 @@ impl Default for NetworkConfig {
     fn default() -> Self {
         Self {
             address: SocketAddr::from(([0, 0, 0, 0], 3000)),
+            only_ipv6: false,
             socket_recv_buffer_size: 4096 * 128,
             #[cfg(feature = "with-mio")]
             poll_event_capacity: 4096,