pingserver: allow setting payload size

refs #2699

Change-Id: I45181845e196ea390f0b6b39165097df510f9116
diff --git a/tools/ping/server/ping-server.cpp b/tools/ping/server/ping-server.cpp
index e75f649..e0d0beb 100644
--- a/tools/ping/server/ping-server.cpp
+++ b/tools/ping/server/ping-server.cpp
@@ -32,6 +32,9 @@
   , m_nPings(0)
   , m_face(face)
 {
+  shared_ptr<Buffer> b = make_shared<Buffer>();
+  b->assign(m_options.payloadSize, 'a');
+  m_payload = Block(tlv::Content, b);
 }
 
 void
@@ -60,11 +63,9 @@
 
   afterReceive(interestName);
 
-  char responseContent[] = "NDN TLV Ping Response";
   shared_ptr<Data> data = make_shared<Data>(interestName);
   data->setFreshnessPeriod(m_options.freshnessPeriod);
-  data->setContent(reinterpret_cast<const uint8_t*>(responseContent),
-                   sizeof(responseContent));
+  data->setContent(m_payload);
   m_keyChain.sign(*data);
   m_face.put(*data);