From 262551ff64b0bea8bc560b0f9723ab1c7047e4f2 Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Mon, 5 May 2025 09:07:35 -0700
Subject: [PATCH] [udp] relax `SocketHandle::Matches()` for host interface
 (#11465)

This commit relaxes the `SocketHandle::Matches()` method to allow a
socket associated with `kNetifUnspecified` to match when
`IsHostInterface()` is set. This is in addition to the existing
behavior of matching a backbone socket under the same condition.
---
 src/core/net/udp6.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/core/net/udp6.cpp b/src/core/net/udp6.cpp
index 4295217ea..ab5eedda9 100644
--- a/src/core/net/udp6.cpp
+++ b/src/core/net/udp6.cpp
@@ -46,7 +46,14 @@ bool Udp::SocketHandle::Matches(const MessageInfo &aMessageInfo) const
     bool matches = false;
 
 #if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
-    VerifyOrExit(IsBackbone() == aMessageInfo.IsHostInterface());
+    if (aMessageInfo.IsHostInterface())
+    {
+        VerifyOrExit(IsBackbone() || (GetNetifId() == kNetifUnspecified));
+    }
+    else
+    {
+        VerifyOrExit(!IsBackbone());
+    }
 #endif
 
     VerifyOrExit(GetSockName().mPort == aMessageInfo.GetSockPort());