Add MetadataObject class to encode/decode RDR-style metadata

Change-Id: I6688b630a4889614e7df5c1f91b91be370a350cd Refs: #4707
7 years ago · 6b99b6f185
6 changed files with 387 additions and 31 deletions
--- a/AUTHORS.md
+++ b/AUTHORS.md
@ -40,3 +40,4 @@ in the library:
 * Susmit Shannigrahi    <https://www.linkedin.com/in/susmit-shannigrahi-90433b8>
 * José Quevedo          <http://atnog.av.it.pt/members/jquevedo>
 * Zhiyi Zhang           <http://irl.cs.ucla.edu/~zhiyi/>
+* Chavoosh Ghasemi      <https://www.linkedin.com/in/chavoosh-ghasemi-421327117/>
--- a/ndn-cxx/metadata-object.cpp
+++ b/ndn-cxx/metadata-object.cpp
@ -0,0 +1,97 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2019 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/>.
+ *
+ * @author Chavoosh Ghasemi <chghasemi@cs.arizona.edu>
+ */
+
+#include "ndn-cxx/metadata-object.hpp"
+
+#include <boost/lexical_cast.hpp>
+
+namespace ndn {
+
+static_assert(std::is_base_of<tlv::Error, MetadataObject::Error>::value,
+              "MetadataObject::Error must inherit from tlv::Error");
+
+const name::Component KEYWORD_METADATA_COMP = "20 08 6D65746164617461"_block; // 32=metadata
+
+MetadataObject::MetadataObject() = default;
+
+MetadataObject::MetadataObject(const Data& data)
+{
+  if (data.getContentType() != tlv::ContentType_Blob) {
+    BOOST_THROW_EXCEPTION(Error("Expected ContentType to be BLOB but " +
+                                boost::lexical_cast<std::string>(data.getContentType()) +
+                                " is provided"));
+  }
+
+  if (!isValidName(data.getName())) {
+    BOOST_THROW_EXCEPTION(Error("Name " + data.getName().toUri() +
+                                " is not a valid MetadataObject name"));
+  }
+
+  data.getContent().parse();
+  // ignore non-Name elements before the first one
+  m_versionedName.wireDecode(data.getContent().get(tlv::Name));
+}
+
+Data
+MetadataObject::makeData(Name discoveryInterestName,
+                         KeyChain& keyChain,
+                         const ndn::security::SigningInfo& si,
+                         optional<uint64_t> version,
+                         time::milliseconds freshnessPeriod) const
+{
+  if (discoveryInterestName.empty() || discoveryInterestName[-1] != KEYWORD_METADATA_COMP) {
+    BOOST_THROW_EXCEPTION(Error("Name " + discoveryInterestName.toUri() +
+                                " is not a valid discovery Interest name"));
+  }
+  discoveryInterestName.appendVersion(version);
+  discoveryInterestName.appendSegment(0);
+
+  Data data(discoveryInterestName);
+  data.setContent(m_versionedName.wireEncode());
+  data.setFreshnessPeriod(freshnessPeriod);
+  keyChain.sign(data, si);
+
+  return data;
+}
+
+MetadataObject&
+MetadataObject::setVersionedName(const Name& name)
+{
+  m_versionedName = name;
+  return *this;
+}
+
+bool
+MetadataObject::isValidName(const Name& name)
+{
+  return name.size() >= 3 && name[-3] == KEYWORD_METADATA_COMP &&
+         name[-2].isVersion() && name[-1].isSegment();
+}
+
+Interest
+MetadataObject::makeDiscoveryInterest(Name name)
+{
+  return Interest(name.append(KEYWORD_METADATA_COMP))
+         .setCanBePrefix(true)
+         .setMustBeFresh(true);
+}
+
+} // namespace ndn
--- a/ndn-cxx/metadata-object.hpp
+++ b/ndn-cxx/metadata-object.hpp
@ -0,0 +1,126 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2019 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/>.
+ *
+ * @author Chavoosh Ghasemi <chghasemi@cs.arizona.edu>
+ */
+
+#ifndef NDN_METADATA_OBJECT_HPP
+#define NDN_METADATA_OBJECT_HPP
+
+#include "ndn-cxx/data.hpp"
+#include "ndn-cxx/interest.hpp"
+#include "ndn-cxx/security/v2/key-chain.hpp"
+
+namespace ndn {
+
+/**
+ * @brief Class for RDR-style metadata encoding/decoding.
+ *
+ * The interest and data packets dealing with metadata (called "discovery interest"
+ * and "metadata", respectively) follow a specific format.
+ * @see https://redmine.named-data.net/projects/ndn-tlv/wiki/RDR
+ *
+ * Realtime Data Retrieval (RDR) is a protocol for discovering the latest version number
+ * of a given data collection. There are two names in an RDR metadata object:
+ * @li the **versioned name** is a prefix of the data collection, and generally
+ *     contains a version component. It appears in the Content element of the metadata object.
+ * @li the **metadata name** is the name of the metadata object itself, and includes
+ *     a keyword name component `32=metadata`, as well as version and segment components.
+ */
+class MetadataObject
+{
+public:
+  class Error : public tlv::Error
+  {
+  public:
+    using tlv::Error::Error;
+  };
+
+  /**
+   * @brief Create an empty metadata object
+   */
+  MetadataObject();
+
+  /**
+   * @brief Construct a metadata object by decoding of the given Data packet
+   * @throw tlv::Error the Data is not a valid metadata packet
+   */
+  explicit
+  MetadataObject(const Data& data);
+
+  /**
+   * @brief Create a Data packet representing this metadata object
+   *
+   * @param discoveryInterestName the discovery Interest's name, which must end with
+   *                              a keyword name component `32=metadata`
+   * @param keyChain KeyChain to sign the Data
+   * @param si signing parameters
+   * @param version version number of metadata packet; if nullopt, use current Unix
+   *                timestamp (in milliseconds) as the version number
+   * @param freshnessPeriod freshness period of metadata packet
+   *
+   * @throw tlv::Error @p discoveryInterestName is not valid
+   */
+  Data
+  makeData(Name discoveryInterestName,
+           KeyChain& keyChain,
+           const ndn::security::SigningInfo& si = KeyChain::getDefaultSigningInfo(),
+           optional<uint64_t> version = nullopt,
+           time::milliseconds freshnessPeriod = 10_ms) const;
+
+  /**
+   * @brief Return the versioned name (i.e., the name inside the content)
+   */
+  const Name&
+  getVersionedName() const
+  {
+    return m_versionedName;
+  }
+
+  /**
+   * @brief Set the versioned name
+   *
+   * Any metadata packet carries a versioned name in its payload where it shows the name
+   * and the latest version of a data stream. For instance, `/ndn/test/%FD%97%47%1E%6C` is
+   * a versioned name that shows the latest version of `/ndn/test`.
+   */
+  MetadataObject&
+  setVersionedName(const Name& name);
+
+public: // static methods
+  /**
+   * @brief Check whether @p name can be a valid metadata name
+   */
+  static bool
+  isValidName(const Name& name);
+
+  /**
+   * @brief Generate a discovery interest packet based on @p name
+   *
+   * @param name prefix of data collection
+   */
+  static Interest
+  makeDiscoveryInterest(Name name);
+
+private:
+  Name m_versionedName;
+};
+
+} // namespace ndn
+
+#endif // NDN_METADATA_OBJECT_HPP
--- a/ndn-cxx/name.cpp
+++ b/ndn-cxx/name.cpp
@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2019 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
@ -211,15 +211,15 @@ Name::getSubName(ssize_t iStartComponent, size_t nComponents) const
 // ---- modifiers ----

 Name&
-Name::appendVersion()
+Name::appendVersion(optional<uint64_t> version)
 {
-  return appendVersion(time::toUnixTimestamp(time::system_clock::now()).count());
+  return append(Component::fromVersion(version.value_or(time::toUnixTimestamp(time::system_clock::now()).count())));
 }

 Name&
-Name::appendTimestamp()
+Name::appendTimestamp(optional<time::system_clock::TimePoint> timestamp)
 {
-  return appendTimestamp(time::system_clock::now());
+  return append(Component::fromTimestamp(timestamp.value_or(time::system_clock::now())));
 }

 Name&
--- a/ndn-cxx/name.hpp
+++ b/ndn-cxx/name.hpp
@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2019 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
@ -355,24 +355,13 @@ public: // modifiers
  }

  /** @brief Append a version component
+   *  @param version the version number to append; if nullopt, the current UNIX time
+   *                 in milliseconds is used
   *  @return a reference to this name, to allow chaining
   *  @sa NDN Naming Conventions https://named-data.net/doc/tech-memos/naming-conventions.pdf
   */
  Name&
-  appendVersion(uint64_t version)
-  {
-    return append(Component::fromVersion(version));
-  }
-
-  /** @brief Append a version component based on current time
-   *
-   *  The version number is the current UNIX timestamp in milliseconds
-   *
-   *  @return a reference to this name, to allow chaining
-   *  @sa NDN Naming Conventions https://named-data.net/doc/tech-memos/naming-conventions.pdf
-   */
-  Name&
-  appendVersion();
+  appendVersion(optional<uint64_t> version = nullopt);

  /** @brief Append a segment number (sequential) component
   *  @return a reference to this name, to allow chaining
@ -395,21 +384,12 @@ public: // modifiers
  }

  /** @brief Append a timestamp component
+   *  @param timestamp the timestamp to append; if nullopt, the current system time is used
   *  @return a reference to this name, to allow chaining
   *  @sa NDN Naming Conventions https://named-data.net/doc/tech-memos/naming-conventions.pdf
   */
  Name&
-  appendTimestamp(const time::system_clock::TimePoint& timePoint)
-  {
-    return append(Component::fromTimestamp(timePoint));
-  }
-
-  /** @brief Append a timestamp component based on current time
-   *  @return a reference to this name, to allow chaining
-   *  @sa NDN Naming Conventions https://named-data.net/doc/tech-memos/naming-conventions.pdf
-   */
-  Name&
-  appendTimestamp();
+  appendTimestamp(optional<time::system_clock::TimePoint> timestamp = nullopt);

  /** @brief Append a sequence number component
   *  @return a reference to this name, to allow chaining
--- a/tests/unit/metadata-object.t.cpp
+++ b/tests/unit/metadata-object.t.cpp
@ -0,0 +1,152 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2019 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/>.
+ *
+ * @author Chavoosh Ghasemi <chghasemi@cs.arizona.edu>
+ */
+
+#include "ndn-cxx/metadata-object.hpp"
+
+#include "tests/boost-test.hpp"
+#include "tests/identity-management-fixture.hpp"
+
+namespace ndn {
+namespace tests {
+
+class MetadataObjectFixture : public IdentityManagementFixture
+{
+public:
+  MetadataObjectFixture()
+    : metadataComponent(32, reinterpret_cast<const uint8_t*>("metadata"), std::strlen("metadata"))
+    , versionedContentName(Name(baseContentName)
+                           .appendVersion(342092199154ULL))
+    , metadataFullName(Name(baseContentName)
+                       .append(metadataComponent)
+                       .appendVersion(metadataVerNo)
+                       .appendSegment(0))
+  {
+  }
+
+protected:
+  const name::Component metadataComponent;
+
+  // content prefix
+  const Name baseContentName = "/ndn/unit/tests";
+  const Name versionedContentName;
+
+  // metadata prefix
+  const uint64_t metadataVerNo = 89400192181ULL;
+  const Name metadataFullName;
+};
+
+BOOST_FIXTURE_TEST_SUITE(TestMetadataObject, MetadataObjectFixture)
+
+BOOST_AUTO_TEST_CASE(EncodeDecode)
+{
+  MetadataObject metadata1;
+  metadata1.setVersionedName(versionedContentName);
+
+  // pass metadata version number
+  const Data data1 = metadata1.makeData(metadataFullName.getPrefix(-2), m_keyChain,
+                                        KeyChain::getDefaultSigningInfo(), metadataVerNo);
+
+  BOOST_CHECK_EQUAL(metadata1.getVersionedName(), versionedContentName);
+  BOOST_CHECK_EQUAL(data1.getName(), metadataFullName);
+  BOOST_CHECK_EQUAL(data1.getFreshnessPeriod(), 10_ms);
+
+  // do not pass metadata version number
+  metadata1.setVersionedName(versionedContentName);
+  const Data data2 = metadata1.makeData(metadataFullName.getPrefix(-2), m_keyChain);
+  BOOST_CHECK_NE(data2.getName()[-2].toVersion(), metadataVerNo);
+
+  // construct a metadata object based on a valid metadata packet
+  MetadataObject metadata2(data1);
+
+  BOOST_CHECK_EQUAL(metadata2.getVersionedName(), versionedContentName);
+  BOOST_CHECK(baseContentName.isPrefixOf(metadata2.makeData(metadataFullName.getPrefix(-2),
+                                                            m_keyChain).getName()));
+}
+
+BOOST_AUTO_TEST_CASE(InvalidFormat)
+{
+  Data data;
+
+  // invalid content type
+  data.setName(Name("/ndn/unit/test").append(metadataComponent));
+  data.setContentType(tlv::ContentType_Key);
+  BOOST_CHECK_THROW(MetadataObject metadata(data), tlv::Error);
+
+  // invalid metadata name
+  data.setName("/ndn/unit/test");
+  data.setContentType(tlv::ContentType_Blob);
+  BOOST_CHECK_THROW(MetadataObject metadata(data), tlv::Error);
+
+  // empty content
+  data.setName(Name("ndn/unit/test").append(metadataComponent));
+  BOOST_CHECK_THROW(MetadataObject metadata(data), tlv::Error);
+
+  // non-empty content with no name element
+  data.setContent("F000"_block);
+  BOOST_CHECK_THROW(MetadataObject metadata(data), tlv::Error);
+}
+
+BOOST_AUTO_TEST_CASE(IsValidName)
+{
+  // valid name
+  Name name = Name("/ndn/unit/test")
+              .append(metadataComponent)
+              .appendVersion()
+              .appendSegment(0);
+  BOOST_CHECK(MetadataObject::isValidName(name));
+
+  // invalid names
+  // segment component is missing
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name.getPrefix(-1)), false);
+
+  // version component is missing
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name.getPrefix(-2)), false);
+
+  // keyword name component `32=keyword` is missing
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name.getPrefix(-3)), false);
+
+  // too short name
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name.getPrefix(-4)), false);
+
+  // out-of-order segment and version components
+  name = name.getPrefix(-2).appendSegment(0).appendVersion();
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name), false);
+
+  // invalid name component keyword
+  name = name.getPrefix(-3)
+         .append(32, reinterpret_cast<const uint8_t*>("foo"), std::strlen("foo"))
+         .appendVersion()
+         .appendSegment(0);
+  BOOST_CHECK_EQUAL(MetadataObject::isValidName(name), false);
+}
+
+BOOST_AUTO_TEST_CASE(MakeDiscoveryInterest)
+{
+  Interest interest = MetadataObject::makeDiscoveryInterest(baseContentName);
+  BOOST_CHECK_EQUAL(interest.getName(), Name(baseContentName).append(metadataComponent));
+  BOOST_CHECK(interest.getCanBePrefix());
+  BOOST_CHECK(interest.getMustBeFresh());
+}
+
+BOOST_AUTO_TEST_SUITE_END() // TestMetadataObject
+
+} // namespace tests
+} // namespace ndn