handle deallocation request in native_resolve_cb

When librdkafka calls the resolve callback with all pointers set to null pointers it is a signal that the callback should deallocate the provided addrinfo. Signed-off-by: Petros Angelatos <[email protected]> Co-authored-by: Nikhil Benesch <[email protected]>
MaterializeInc · Jan 30, 2024 · 8b419f8 · 8b419f8
1 parent 6e957d5
commit 8b419f8
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/src/client.rs b/src/client.rs
@@ -525,6 +525,15 @@ pub(crate) unsafe extern "C" fn native_resolve_cb<C: ClientContext>(
     res: *mut *mut addrinfo,
     opaque: *mut c_void,
 ) -> i32 {
+    if node.is_null() {
+        // If `node`` is `NULL`, we expect `service` and `hints` to also be
+        // `NULL`, and altogether this indicates a request to free `res`.
+        assert!(service.is_null());
+        assert!(hints.is_null());
+        unsafe { libc::freeaddrinfo(*res) }
+        return 0; // NOTE: this return code is ignored by librdkafka in this code path
+    }
+
     // Convert host and port to Rust strings.
     let host = match CStr::from_ptr(node).to_str() {
         Ok(host) => host.into(),