From 1edf915bd638e9070a0e49d976836cc8c18d5ede Mon Sep 17 00:00:00 2001
From: Benjamin Saunders <ben.e.saunders@gmail.com>
Date: Mon, 25 Mar 2024 12:57:41 -0700
Subject: [PATCH] Validate preferred_address transport parameter

---
 quinn-proto/src/connection/mod.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/quinn-proto/src/connection/mod.rs b/quinn-proto/src/connection/mod.rs
index 27111f1a00..d3f8c5b810 100644
--- a/quinn-proto/src/connection/mod.rs
+++ b/quinn-proto/src/connection/mod.rs
@@ -3207,6 +3207,19 @@ impl Connection {
             ));
         }
 
+        if let Some(preferred) = params.preferred_address {
+            if self.side.is_server() {
+                return Err(TransportError::TRANSPORT_PARAMETER_ERROR(
+                    "client sent preferred_address",
+                ));
+            }
+            if preferred.connection_id.is_empty() {
+                return Err(TransportError::TRANSPORT_PARAMETER_ERROR(
+                    "preferred_address must not have a zero-length connection ID",
+                ));
+            }
+        }
+
         self.set_peer_params(params);
 
         Ok(())