From a0b84f865ccd3ad9bf3d9e0f3dd2ca13fb4ee736 Mon Sep 17 00:00:00 2001
From: Andrei Litvin <andreilitvin@google.com>
Date: Tue, 17 Dec 2024 10:07:18 -0500
Subject: [PATCH] Update non-LL interface for the dedup logic as well

---
 .../AddressResolve_DefaultImpl.cpp            | 28 +++++++++++--------
 .../tests/TestAddressResolve_DefaultImpl.cpp  |  8 ++++++
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/src/lib/address_resolve/AddressResolve_DefaultImpl.cpp b/src/lib/address_resolve/AddressResolve_DefaultImpl.cpp
index 1df91dc7985989..884016f26558bd 100644
--- a/src/lib/address_resolve/AddressResolve_DefaultImpl.cpp
+++ b/src/lib/address_resolve/AddressResolve_DefaultImpl.cpp
@@ -15,6 +15,7 @@
  *    limitations under the License.
  */
 
+#include "transport/raw/PeerAddress.h"
 #include <lib/address_resolve/AddressResolve_DefaultImpl.h>
 
 #include <lib/address_resolve/TracingStructs.h>
@@ -128,6 +129,17 @@ NodeLookupAction NodeLookupHandle::NextAction(System::Clock::Timestamp now)
 
 bool NodeLookupResults::UpdateResults(const ResolveResult & result, const Dnssd::IPAddressSorter::IpScore newScore)
 {
+    Transport::PeerAddress addressWithAdjustedInterface = result.address;
+    if (!addressWithAdjustedInterface.GetIPAddress().IsIPv6LinkLocal())
+    {
+        // Only use the DNS-SD resolution's InterfaceID for addresses that are IPv6 LLA.
+        // For all other addresses, we should rely on the device's routing table to route messages sent.
+        // Forcing messages down an InterfaceId might fail. For example, in bridged networks like Thread,
+        // mDNS advertisements are not usually received on the same interface the peer is reachable on.
+        addressWithAdjustedInterface.SetInterface(Inet::InterfaceId::Null());
+        ChipLogDetail(Discovery, "Lookup clearing interface for non LL address");
+    }
+
     uint8_t insertAtIndex = 0;
     for (; insertAtIndex < kNodeLookupResultsLen; insertAtIndex++)
     {
@@ -139,7 +151,7 @@ bool NodeLookupResults::UpdateResults(const ResolveResult & result, const Dnssd:
 
         auto & oldAddress = results[insertAtIndex].address;
 
-        if (oldAddress == result.address)
+        if (oldAddress == addressWithAdjustedInterface)
         {
             // this address is already in our list.
             return false;
@@ -179,17 +191,9 @@ bool NodeLookupResults::UpdateResults(const ResolveResult & result, const Dnssd:
         count++;
     }
 
-    auto & updatedResult = results[insertAtIndex];
-    updatedResult        = result;
-    if (!updatedResult.address.GetIPAddress().IsIPv6LinkLocal())
-    {
-        // Only use the DNS-SD resolution's InterfaceID for addresses that are IPv6 LLA.
-        // For all other addresses, we should rely on the device's routing table to route messages sent.
-        // Forcing messages down an InterfaceId might fail. For example, in bridged networks like Thread,
-        // mDNS advertisements are not usually received on the same interface the peer is reachable on.
-        updatedResult.address.SetInterface(Inet::InterfaceId::Null());
-        ChipLogDetail(Discovery, "Lookup clearing interface for non LL address");
-    }
+    auto & updatedResult  = results[insertAtIndex];
+    updatedResult         = result;
+    updatedResult.address = addressWithAdjustedInterface;
 
     return true;
 }
diff --git a/src/lib/address_resolve/tests/TestAddressResolve_DefaultImpl.cpp b/src/lib/address_resolve/tests/TestAddressResolve_DefaultImpl.cpp
index 5d6f9e21ff88f4..9bdc52e9850dbb 100644
--- a/src/lib/address_resolve/tests/TestAddressResolve_DefaultImpl.cpp
+++ b/src/lib/address_resolve/tests/TestAddressResolve_DefaultImpl.cpp
@@ -44,6 +44,14 @@ using chip::Dnssd::IPAddressSorter::ScoreIpAddress;
 
 constexpr uint8_t kNumberOfAvailableSlots = CHIP_CONFIG_MDNS_RESOLVE_LOOKUP_RESULTS;
 
+/// Get an address that should have `kUniqueLocal` (one of the lowest) priority.
+///
+/// Since for various tests we check filling the cache with values, we allow
+/// unique address generation by varying the `idx` parameter
+///
+/// @param idx - a value to generate a unique IP address (in case we do not wand dedups)
+/// @param port - port in case some tests would like to vary it. Required for PeerAddress
+/// @param interfaceId - interface required for PeerAddress
 Transport::PeerAddress GetAddressWithLowScore(uint16_t idx = 4, uint16_t port = CHIP_PORT,
                                               Inet::InterfaceId interfaceId = Inet::InterfaceId::Null())
 {