face: handle PcapHelper::Error when applying multicast configuration

When the network interface state is changed, NFD reconfigures its
multicast ethernet faces. The code responsible for this is prone to
a TOCTOU race condition, e.g., if an interface is quickly brought up
and then down again. This currently raises an uncaught exception when
we try to set a packet filter for that interface.

Prevent this issue by catching PcapHelper errors in the same manner
as we catch EthernetTransport errors, and skip creating the face.

Refs: #5297
Change-Id: I9f91ac7c42dec06de34128cb34d6de8bb57e8cf5
diff --git a/daemon/face/ethernet-factory.cpp b/daemon/face/ethernet-factory.cpp
index 59f0c5c..ee887c0 100644
--- a/daemon/face/ethernet-factory.cpp
+++ b/daemon/face/ethernet-factory.cpp
@@ -26,6 +26,7 @@
 #include "ethernet-factory.hpp"
 #include "generic-link-service.hpp"
 #include "multicast-ethernet-transport.hpp"
+#include "pcap-helper.hpp"
 
 #include <boost/range/adaptors.hpp>
 #include <boost/range/algorithm/copy.hpp>
@@ -337,6 +338,10 @@
     NFD_LOG_WARN("Cannot create multicast face on " << netif.getName() << ": " << e.what());
     return nullptr;
   }
+  catch (const PcapHelper::Error& e) {
+    NFD_LOG_WARN("Cannot create multicast face on " << netif.getName() << ": " << e.what());
+    return nullptr;
+  }
 
   if (face->getId() == INVALID_FACEID) {
     // new face: register with forwarding