totally refactored

src/utils/socket_addr.rs

@@ -0,0 +1,63 @@
+use std::net::{IpAddr, Ipv4Addr, SocketAddr};
+
+pub trait ToCanonical {
+  fn to_canonical(&self) -> Self;
+}
+
+impl ToCanonical for SocketAddr {
+  fn to_canonical(&self) -> Self {
+    match self {
+      SocketAddr::V4(_) => *self,
+      SocketAddr::V6(v6) => match v6.ip().to_ipv4() {
+        Some(mapped) => {
+          if mapped == Ipv4Addr::new(0, 0, 0, 1) {
+            *self
+          } else {
+            SocketAddr::new(IpAddr::V4(mapped), self.port())
+          }
+        }
+        None => *self,
+      },
+    }
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use std::net::Ipv6Addr;
+  #[test]
+  fn ipv4_loopback_to_canonical() {
+    let socket = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8080);
+    assert_eq!(socket.to_canonical(), socket);
+  }
+  #[test]
+  fn ipv6_loopback_to_canonical() {
+    let socket = SocketAddr::new(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1)), 8080);
+    assert_eq!(socket.to_canonical(), socket);
+  }
+  #[test]
+  fn ipv4_to_canonical() {
+    let socket = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(192, 168, 1, 1)), 8080);
+    assert_eq!(socket.to_canonical(), socket);
+  }
+  #[test]
+  fn ipv6_to_canonical() {
+    let socket = SocketAddr::new(
+      IpAddr::V6(Ipv6Addr::new(0x2001, 0x0db8, 0, 0, 0, 0, 0xdead, 0xbeef)),
+      8080,
+    );
+    assert_eq!(socket.to_canonical(), socket);
+  }
+  #[test]
+  fn ipv4_mapped_to_ipv6_to_canonical() {
+    let socket = SocketAddr::new(
+      IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff)),
+      8080,
+    );
+    assert_eq!(
+      socket.to_canonical(),
+      SocketAddr::new(IpAddr::V4(Ipv4Addr::new(192, 10, 2, 255)), 8080)
+    );
+  }
+}