tools: display Nack counters in nfd-status

refs #3569

Change-Id: I59e76d421502417a13efbf088284d278da07bae4
diff --git a/tools/nfd-status-http-server-files/nfd-status.xsl b/tools/nfd-status-http-server-files/nfd-status.xsl
index fcf128b..f8ba4c8 100644
--- a/tools/nfd-status-http-server-files/nfd-status.xsl
+++ b/tools/nfd-status-http-server-files/nfd-status.xsl
@@ -87,6 +87,8 @@
         <th>Out Interests</th>
         <th>In Data</th>
         <th>Out Data</th>
+        <th>In Nacks</th>
+        <th>Out Nacks</th>
       </tr>
     </thead>
     <tbody>
@@ -105,6 +107,8 @@
         <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nInterests"/></td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:incomingPackets/nfd:nDatas"/></td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nDatas"/></td>
+        <td><xsl:value-of select="nfd:packetCounters/nfd:incomingPackets/nfd:nNacks"/></td>
+        <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nNacks"/></td>
       </tr>
     </tbody>
   </table>
@@ -150,9 +154,11 @@
         <th>Expires in</th>
         <th>In Interests</th>
         <th>In Data</th>
+        <th>In Nacks</th>
         <th>In Bytes</th>
         <th>Out Interests</th>
         <th>Out Data</th>
+        <th>Out Nacks</th>
         <th>Out Bytes</th>
       </tr>
     </thead>
@@ -185,9 +191,11 @@
         </td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:incomingPackets/nfd:nInterests"/></td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:incomingPackets/nfd:nDatas"/></td>
+        <td><xsl:value-of select="nfd:packetCounters/nfd:incomingPackets/nfd:nNacks"/></td>
         <td><xsl:value-of select="nfd:byteCounters/nfd:incomingBytes"/></td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nInterests"/></td>
         <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nDatas"/></td>
+        <td><xsl:value-of select="nfd:packetCounters/nfd:outgoingPackets/nfd:nNacks"/></td>
         <td><xsl:value-of select="nfd:byteCounters/nfd:outgoingBytes"/></td>
       </tr>
       </xsl:for-each>
diff --git a/tools/nfd-status.cpp b/tools/nfd-status.cpp
index a904827..21c62a1 100644
--- a/tools/nfd-status.cpp
+++ b/tools/nfd-status.cpp
@@ -243,12 +243,16 @@
                 << "</nInterests>";
       std::cout << "<nDatas>"               << status.getNInDatas()
                 << "</nDatas>";
+      std::cout << "<nNacks>"               << status.getNInNacks()
+                << "</nNacks>";
       std::cout << "</incomingPackets>";
       std::cout << "<outgoingPackets>";
       std::cout << "<nInterests>"           << status.getNOutInterests()
                 << "</nInterests>";
       std::cout << "<nDatas>"               << status.getNOutDatas()
                 << "</nDatas>";
+      std::cout << "<nNacks>"               << status.getNOutNacks()
+                << "</nNacks>";
       std::cout << "</outgoingPackets>";
       std::cout << "</packetCounters>";
       std::cout << "</generalStatus>";
@@ -276,6 +280,8 @@
       std::cout << "         nOutInterests=" << status.getNOutInterests()        << std::endl;
       std::cout << "              nInDatas=" << status.getNInDatas()             << std::endl;
       std::cout << "             nOutDatas=" << status.getNOutDatas()            << std::endl;
+      std::cout << "              nInNacks=" << status.getNInNacks()             << std::endl;
+      std::cout << "             nOutNacks=" << status.getNOutNacks()            << std::endl;
     }
 
     runNextStep();
@@ -420,12 +426,16 @@
                   << "</nInterests>";
         std::cout << "<nDatas>"           << faceStatus.getNInDatas()
                   << "</nDatas>";
+        std::cout << "<nNacks>"           << faceStatus.getNInNacks()
+                  << "</nNacks>";
         std::cout << "</incomingPackets>";
         std::cout << "<outgoingPackets>";
         std::cout << "<nInterests>"       << faceStatus.getNOutInterests()
                   << "</nInterests>";
         std::cout << "<nDatas>"           << faceStatus.getNOutDatas()
                   << "</nDatas>";
+        std::cout << "<nNacks>"           << faceStatus.getNOutNacks()
+                  << "</nNacks>";
         std::cout << "</outgoingPackets>";
         std::cout << "</packetCounters>";
 
@@ -468,9 +478,11 @@
         std::cout << " counters={"
                   << "in={" << faceStatus.getNInInterests() << "i "
                   << faceStatus.getNInDatas() << "d "
+                  << faceStatus.getNInNacks() << "n "
                   << faceStatus.getNInBytes() << "B}"
                   << " out={" << faceStatus.getNOutInterests() << "i "
                   << faceStatus.getNOutDatas() << "d "
+                  << faceStatus.getNOutNacks() << "n "
                   << faceStatus.getNOutBytes() << "B}"
                   << "}";
         std::cout << " " << faceStatus.getFaceScope()