[Darwin][Network.framework] Append interface scope for IPv6 multicast and match incoming packets by interface in Connections (#39430)

Author: vivien-apple

src/platform/Darwin/inet/UDPEndPointImplNetworkFramework.mm

@@ -234,7 +234,7 @@
 #endif // INET_CONFIG_ENABLE_IPV4
         {
             aAddress.ToString(addrStr);
-            if (interfaceIndex != InterfaceId::Null() && aAddress.IsIPv6LinkLocal()) {
+            if (interfaceIndex != InterfaceId::Null() && (aAddress.IsIPv6LinkLocal() || aAddress.IsIPv6Multicast())) {
                 char interface[InterfaceId::kMaxIfNameLength + 1] = {}; // +1 to prepend '%'
                 interface[0] = '%';
                 interface[1] = 0;

src/platform/Darwin/inet/UDPEndPointImplNetworkFrameworkConnection.mm

@@ -336,9 +336,22 @@
 
             IPAddress remoteAddress;
             IPAddress::GetIPAddressFromSockAddr(*nw_endpoint_get_address(remoteEndpoint), remoteAddress);
+            VerifyOrReturnValue(pktInfo.DestAddress == remoteAddress, false);
+
             const uint16_t remotePort = nw_endpoint_get_port(remoteEndpoint);
+            VerifyOrReturnValue(pktInfo.DestPort == remotePort, false);
+
+            if (pktInfo.Interface != InterfaceId::Null()) {
+                uint32_t interfaceIndex = 0;
+                __auto_type * sa = nw_endpoint_get_address(remoteEndpoint);
+                if (sa && sa->sa_family == AF_INET6) {
+                    __auto_type in6 = reinterpret_cast<const struct sockaddr_in6 *>(sa);
+                    interfaceIndex = static_cast<uint32_t>(in6->sin6_scope_id);
+                    VerifyOrReturnValue(interfaceIndex == pktInfo.Interface.GetPlatformInterface(), false);
+                }
+            }
 
-            return pktInfo.DestAddress == remoteAddress && pktInfo.DestPort == remotePort;
+            return true;
         }
 
         void UDPEndPointImplNetworkFrameworkConnection::ConnectionWrapper::RefreshTimeout()