security: Add v2::Validator implementation

Based on the code originally written by Qiuhan Ding

Change-Id: Ib66e24f49d0b6fb2ae21ea1fca7b9ec62ecb753a
Refs: #3289, #1872
diff --git a/src/security/v2/validation-policy-simple-hierarchy.cpp b/src/security/v2/validation-policy-simple-hierarchy.cpp
new file mode 100644
index 0000000..ee1ad94
--- /dev/null
+++ b/src/security/v2/validation-policy-simple-hierarchy.cpp
@@ -0,0 +1,78 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2017 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "validation-policy-simple-hierarchy.hpp"
+
+namespace ndn {
+namespace security {
+namespace v2 {
+
+void
+ValidationPolicySimpleHierarchy::checkPolicy(const Data& data, const shared_ptr<ValidationState>& state,
+                                             const ValidationContinuation& continueValidation)
+{
+  if (!data.getSignature().hasKeyLocator()) {
+    return state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Required key locator is missing"});
+  }
+  const KeyLocator& locator = data.getSignature().getKeyLocator();
+  if (locator.getType() != KeyLocator::KeyLocator_Name) {
+    return state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Key locator not Name"});
+  }
+  if (locator.getName().getPrefix(-2).isPrefixOf(data.getName())) {
+    continueValidation(make_shared<CertificateRequest>(Interest(locator.getName())), state);
+  }
+  else {
+    state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Data signing policy violation for " +
+                 data.getName().toUri() + " by " + locator.getName().toUri()});
+  }
+}
+
+void
+ValidationPolicySimpleHierarchy::checkPolicy(const Interest& interest, const shared_ptr<ValidationState>& state,
+                                             const ValidationContinuation& continueValidation)
+{
+  SignatureInfo info;
+  try {
+    info.wireDecode(interest.getName().at(signed_interest::POS_SIG_INFO).blockFromValue());
+  }
+  catch (const tlv::Error& e) {
+    return state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Invalid signed interest (" +
+                        std::string(e.what()) + ")"});
+  }
+  if (!info.hasKeyLocator()) {
+    return state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Required key locator is missing"});
+  }
+  const KeyLocator& locator = info.getKeyLocator();
+  if (locator.getType() != KeyLocator::KeyLocator_Name) {
+    return state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Key locator not Name"});
+  }
+  if (locator.getName().getPrefix(-2).isPrefixOf(interest.getName())) {
+    continueValidation(make_shared<CertificateRequest>(Interest(locator.getName())), state);
+  }
+  else {
+    state->fail({ValidationError::Code::INVALID_KEY_LOCATOR, "Interest signing policy violation for " +
+                 interest.getName().toUri() + " by " + locator.getName().toUri()});
+  }
+}
+
+} // namespace v2
+} // namespace security
+} // namespace ndn