mgmt: fix InternalFace::processInterest crash when Interest is gone

Interest may be satisfied by Notification and be removed from PIT
between sendInterest and processInterest.

refs #1452

Change-Id: I0c3e05c34f0d8607d96dcfd156a3e87c1ecb26f2
diff --git a/daemon/mgmt/internal-face.cpp b/daemon/mgmt/internal-face.cpp
index 51af45b..de77009 100644
--- a/daemon/mgmt/internal-face.cpp
+++ b/daemon/mgmt/internal-face.cpp
@@ -42,13 +42,22 @@
 
   // Invoke .processInterest a bit later,
   // to avoid potential problems in forwarding pipelines.
+  weak_ptr<const Interest> interestWeak = interest.shared_from_this();
   getGlobalIoService().post(bind(&InternalFace::processInterest,
-                                 this, boost::cref(interest)));
+                                 this, interestWeak));
 }
 
 void
-InternalFace::processInterest(const Interest& interest)
+InternalFace::processInterest(weak_ptr<const Interest> interestWeak)
 {
+  shared_ptr<const Interest> interestPtr = interestWeak.lock();
+  if (!static_cast<bool>(interestPtr)) {
+    // Interest is gone because it's satisfied and removed from PIT
+    NFD_LOG_DEBUG("processInterest: Interest is gone");
+    return;
+  }
+  const Interest& interest = *interestPtr;
+
   if (m_interestFilters.size() == 0)
     {
       NFD_LOG_DEBUG("no Interest filters to match against");