Fix mirrord making double bind of port 0 fail (metalbear-co#2811)

changelog.d/+fix-double-bind-zero.fixed.md

@@ -0,0 +1 @@
+Fix mirrord making double bind of port 0 fail

mirrord/layer/src/socket/ops.rs

@@ -279,15 +279,17 @@ pub(super) fn bind(
     // Check if the user's requested address isn't already in use, even though it's not actually
     // bound, as we bind to a different address, but if we don't check for this then we're
     // changing normal socket behavior (see issue #1123).
-    if SOCKETS
-        .lock()?
-        .iter()
-        .any(|(_, socket)| match &socket.state {
-            SocketState::Initialized | SocketState::Connected(_) => false,
-            SocketState::Bound(bound) | SocketState::Listening(bound) => {
-                bound.requested_address == requested_address
-            }
-        })
+    // We check that port isn't 0 because if it's port 0 it can't really conflict.
+    if requested_address.port() != 0
+        && SOCKETS
+            .lock()?
+            .iter()
+            .any(|(_, socket)| match &socket.state {
+                SocketState::Initialized | SocketState::Connected(_) => false,
+                SocketState::Bound(bound) | SocketState::Listening(bound) => {
+                    bound.requested_address == requested_address
+                }
+            })
     {
         Err(HookError::AddressAlreadyBound(requested_address))?;
     }