Avoid crash in mirror if nextHop Ip type does not match the dest IP type

Summary:
in S455663, wedge agent crashed on some boxes when v4 mirror was configured and nexthops were resolved to v6. While there were configuration issues, wedge agent crash also needs to be addressed.

Ensure that if the nexthop address type and mirror dest address type vary, the nexthop is not picked up

Reviewed By: phshaikh

Differential Revision: D66032846

fbshipit-source-id: a90afc782704e88cc6efc7998b05706aa9c38032

fboss/agent/MirrorManagerImpl.cpp

@@ -70,6 +70,7 @@ PortID MirrorManagerImpl<AddrT>::getEventorPortForSflowMirror(
 template <typename AddrT>
 std::shared_ptr<Mirror> MirrorManagerImpl<AddrT>::updateMirror(
     const std::shared_ptr<Mirror>& mirror) {
+  bool isV4 = std::is_same_v<AddrT, folly::IPAddressV4>;
   const AddrT destinationIp =
       getIPAddress<AddrT>(mirror->getDestinationIp().value());
   const auto state = sw_->getState();
@@ -91,6 +92,10 @@ std::shared_ptr<Mirror> MirrorManagerImpl<AddrT>::updateMirror(
   newMirror->setSwitchId(mirror->getSwitchId());
 
   for (const auto& nexthop : nexthops) {
+    // Dont consider nextHops that do not match incoming Address family
+    if (isV4 != nexthop.addr().isV4()) {
+      continue;
+    }
     const auto entry =
         resolveMirrorNextHopNeighbor(state, mirror, destinationIp, nexthop);