Merge pull request #1744

a5a0a3c8 core: updates can now be downloaded (and SHA256 hash checked) (moneromooo-monero)
216f062e util: add a SHA256 function (moneromooo-monero)
4bf78492 mlog: only silence errors for net by default, not net.* (moneromooo-monero)
d282cfcc core: test key images against validity domain (moneromooo-monero)
efb72e74 http_client: add a couple consts (moneromooo-monero)
f640512c Optionally query moneropulse DNS records to check for updates (moneromooo-monero)
e3cae4ae core: display any fork warning at startup too (moneromooo-monero)
969ad710 dns_utils: fix first checked DNS entry being ignored (moneromooo-monero)
08c3f380 util: add a vercmp function to compare version numbers (moneromooo-monero)
e8a7525c dns_utils: factor TXT record loading code from checkpoint code (moneromooo-monero)

21 files changed, 710 insertions, 126 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f59493345..c01be24d4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -88,6 +88,14 @@ else()
   set(OPT_FLAGS_RELEASE "-Ofast")
 endif()
 
+# BUILD_TAG is used to select the build type to check for a new version
+if(BUILD_TAG)
+  message(STATUS "Building build tag ${BUILD_TAG}")
+  add_definitions("-DBUILD_TAG=${BUILD_TAG}")
+else()
+  message(STATUS "Building without build tag")
+endif()
+
 set(CMAKE_C_FLAGS_RELEASE "-DNDEBUG ${OPT_FLAGS_RELEASE}")
 set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${OPT_FLAGS_RELEASE}")
 
diff --git a/Makefile b/Makefile
index e6517ebac..3ee9d0e3e 100644
--- a/Makefile
+++ b/Makefile
@@ -58,43 +58,55 @@ release-all:
 	mkdir -p build/release
 	cd build/release && cmake -D BUILD_TESTS=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
 
+release-static:
+	mkdir -p build/release
+	cd build/release && cmake -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+
 coverage:
 	mkdir -p build/debug
 	cd build/debug && cmake -D BUILD_TESTS=ON -D CMAKE_BUILD_TYPE=Debug -D COVERAGE=ON ../.. && $(MAKE) && $(MAKE) test
 
-release-static-armv6:
+# Targets for specific prebuilt builds which will be advertised for updates by their build tag
+
+release-static-linux-armv6:
 	mkdir -p build/release
-	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv6zk" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv6zk" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="linux-armv6" ../.. && $(MAKE)
 
-release-static-armv7:
+release-static-linux-armv7:
 	mkdir -p build/release
-	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv7-a" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv7-a" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="linux-armv7" ../.. && $(MAKE)
 
 release-static-android:
 	mkdir -p build/release
-	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv7-a" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release -D ANDROID=true -D INSTALL_VENDORED_LIBUNBOUND=ON ../.. && $(MAKE)
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv7-a" -D STATIC=ON -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release -D ANDROID=true -D INSTALL_VENDORED_LIBUNBOUND=ON -D BUILD_TAG="android"../.. && $(MAKE)
 
-release-static-armv8:
+release-static-linux-armv8:
 	mkdir -p build/release
-	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv8-a" -D STATIC=ON -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv8-a" -D STATIC=ON -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="linux-armv8" ../.. && $(MAKE)
 
-release-static: release-static-64
+release-static-linux-x86_64:
+	mkdir -p build/release
+	cd build/release && cmake -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="linux-x64" ../.. && $(MAKE)
 
-release-static-64:
+release-static-freebsd-x86_64:
 	mkdir -p build/release
-	cd build/release && cmake -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	cd build/release && cmake -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="freebsd-x64" ../.. && $(MAKE)
+
+release-static-freebsd-x86_64:
+	mkdir -p build/release
+	cd build/release && cmake -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="mac-x64" ../.. && $(MAKE)
 
-release-static-32:
+release-static-linux-i686:
 	mkdir -p build/release
-	cd build/release && cmake -D STATIC=ON -D ARCH="i686" -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	cd build/release && cmake -D STATIC=ON -D ARCH="i686" -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=release -D BUILD_TAG="linux-x86" ../.. && $(MAKE)
 
 release-static-win64:
 	mkdir -p build/release
-	cd build/release && cmake -G "MSYS Makefiles" -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=Release -D CMAKE_TOOLCHAIN_FILE=../../cmake/64-bit-toolchain.cmake -D MSYS2_FOLDER=c:/msys64 ../.. && $(MAKE)
+	cd build/release && cmake -G "MSYS Makefiles" -D STATIC=ON -D ARCH="x86-64" -D BUILD_64=ON -D CMAKE_BUILD_TYPE=Release -D BUILD_TAG="win-x64" -D CMAKE_TOOLCHAIN_FILE=../../cmake/64-bit-toolchain.cmake -D MSYS2_FOLDER=c:/msys64 ../.. && $(MAKE)
 
 release-static-win32:
 	mkdir -p build/release
-	cd build/release && cmake -G "MSYS Makefiles" -D STATIC=ON -D ARCH="i686" -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=Release -D CMAKE_TOOLCHAIN_FILE=../../cmake/32-bit-toolchain.cmake -D MSYS2_FOLDER=c:/msys32 ../.. && $(MAKE)
+	cd build/release && cmake -G "MSYS Makefiles" -D STATIC=ON -D ARCH="i686" -D BUILD_64=OFF -D CMAKE_BUILD_TYPE=Release -D BUILD_TAG="win-x32" -D CMAKE_TOOLCHAIN_FILE=../../cmake/32-bit-toolchain.cmake -D MSYS2_FOLDER=c:/msys32 ../.. && $(MAKE)
 
 clean:
 	@echo "WARNING: Back-up your wallet if it exists within ./build!" ; \
diff --git a/contrib/epee/include/net/http_client.h b/contrib/epee/include/net/http_client.h
index 3d8c759cd..d73eda39c 100644
--- a/contrib/epee/include/net/http_client.h
+++ b/contrib/epee/include/net/http_client.h
@@ -107,14 +107,14 @@ using namespace std;
 	//---------------------------------------------------------------------------
 	static inline const char* get_hex_vals()
 	{
-		static char hexVals[16] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
+		static const char hexVals[16] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
 		return hexVals;
 	}
 
 	static inline const char* get_unsave_chars()
 	{
 		//static char unsave_chars[] = "\"<>%\\^[]`+$,@:;/!#?=&";
-		static char unsave_chars[] = "\"<>%\\^[]`+$,@:;!#&";
+		static const char unsave_chars[] = "\"<>%\\^[]`+$,@:;!#&";
 		return unsave_chars;
 	}
 
diff --git a/contrib/epee/src/mlog.cpp b/contrib/epee/src/mlog.cpp
index c212456f6..995674abd 100644
--- a/contrib/epee/src/mlog.cpp
+++ b/contrib/epee/src/mlog.cpp
@@ -88,7 +88,7 @@ static const char *get_default_categories(int level)
   switch (level)
   {
     case 0:
-      categories = "*:WARNING,net*:FATAL,global:INFO,verify:FATAL,stacktrace:INFO";
+      categories = "*:WARNING,net:FATAL,global:INFO,verify:FATAL,stacktrace:INFO";
       break;
     case 1:
       categories = "*:WARNING,global:INFO,stacktrace:INFO";
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index c63d9d0ae..eb4d4c25d 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -30,12 +30,14 @@ set(common_sources
   base58.cpp
   command_line.cpp
   dns_utils.cpp
+  download.cpp
   util.cpp
   i18n.cpp
   password.cpp
   perf_timer.cpp
   task_region.cpp
-  thread_group.cpp)
+  thread_group.cpp
+  updates.cpp)
 
 if (STACK_TRACE)
   list(APPEND common_sources stack_trace.cpp)
@@ -49,6 +51,7 @@ set(common_private_headers
   command_line.h
   common_fwd.h
   dns_utils.h
+  download.h
   http_connection.h
   int-util.h
   pod-class.h
@@ -62,7 +65,8 @@ set(common_private_headers
   perf_timer.h
   stack_trace.h
   task_region.h
-  thread_group.h)
+  thread_group.h
+  updates.h)
 
 monero_private_headers(common
   ${common_private_headers})
@@ -74,6 +78,7 @@ target_link_libraries(common
   PUBLIC
     epee
     crypto
+    -lcrypto
     ${UNBOUND_LIBRARY}
     ${LIBUNWIND_LIBRARIES}
     ${Boost_DATE_TIME_LIBRARY}
diff --git a/src/common/command_line.cpp b/src/common/command_line.cpp
index c3df5c096..8739a93cd 100644
--- a/src/common/command_line.cpp
+++ b/src/common/command_line.cpp
@@ -120,4 +120,9 @@ namespace command_line
   , "How many blocks to sync at once during chain synchronization."
   , BLOCKS_SYNCHRONIZING_DEFAULT_COUNT
   };
+  const command_line::arg_descriptor<std::string> arg_check_updates = {
+    "check-updates"
+  , "Check for new versions of monero: [disabled|notify|download|update]"
+  , "notify"
+  };
 }
diff --git a/src/common/command_line.h b/src/common/command_line.h
index a09365a6b..f10e68e13 100644
--- a/src/common/command_line.h
+++ b/src/common/command_line.h
@@ -218,4 +218,5 @@ namespace command_line
   extern const arg_descriptor<uint64_t> arg_prep_blocks_threads;
   extern const arg_descriptor<uint64_t> arg_show_time_stats;
   extern const arg_descriptor<size_t> arg_block_sync_size;
+  extern const arg_descriptor<std::string> arg_check_updates;
 }
diff --git a/src/common/dns_utils.cpp b/src/common/dns_utils.cpp
index 5ff39574c..f7655e3c7 100644
--- a/src/common/dns_utils.cpp
+++ b/src/common/dns_utils.cpp
@@ -37,6 +37,7 @@
 
 #include <stdlib.h>
 #include "include_base_utils.h"
+#include <random>
 #include <boost/filesystem/fstream.hpp>
 using namespace epee;
 namespace bf = boost::filesystem;
@@ -451,6 +452,107 @@ std::string get_account_address_as_str_from_url(const std::string& url, bool& dn
   return addresses[0];
 }
 
+namespace
+{
+  bool dns_records_match(const std::vector<std::string>& a, const std::vector<std::string>& b)
+  {
+    if (a.size() != b.size()) return false;
+
+    for (const auto& record_in_a : a)
+    {
+      bool ok = false;
+      for (const auto& record_in_b : b)
+      {
+	if (record_in_a == record_in_b)
+	{
+	  ok = true;
+	  break;
+	}
+      }
+      if (!ok) return false;
+    }
+
+    return true;
+  }
+}
+
+bool load_txt_records_from_dns(std::vector<std::string> &good_records, const std::vector<std::string> &dns_urls)
+{
+  std::vector<std::vector<std::string> > records;
+  records.resize(dns_urls.size());
+
+  std::random_device rd;
+  std::mt19937 gen(rd());
+  std::uniform_int_distribution<int> dis(0, dns_urls.size() - 1);
+  size_t first_index = dis(gen);
+
+  bool avail, valid;
+  size_t cur_index = first_index;
+  do
+  {
+    std::string url = dns_urls[cur_index];
+
+    records[cur_index] = tools::DNSResolver::instance().get_txt_record(url, avail, valid);
+    if (!avail)
+    {
+      records[cur_index].clear();
+      LOG_PRINT_L2("DNSSEC not available for checkpoint update at URL: " << url << ", skipping.");
+    }
+    if (!valid)
+    {
+      records[cur_index].clear();
+      LOG_PRINT_L2("DNSSEC validation failed for checkpoint update at URL: " << url << ", skipping.");
+    }
+
+    cur_index++;
+    if (cur_index == dns_urls.size())
+    {
+      cur_index = 0;
+    }
+  } while (cur_index != first_index);
+
+  size_t num_valid_records = 0;
+
+  for( const auto& record_set : records)
+  {
+    if (record_set.size() != 0)
+    {
+      num_valid_records++;
+    }
+  }
+
+  if (num_valid_records < 2)
+  {
+    LOG_PRINT_L0("WARNING: no two valid MoneroPulse DNS checkpoint records were received");
+    return false;
+  }
+
+  int good_records_index = -1;
+  for (size_t i = 0; i < records.size() - 1; ++i)
+  {
+    if (records[i].size() == 0) continue;
+
+    for (size_t j = i + 1; j < records.size(); ++j)
+    {
+      if (dns_records_match(records[i], records[j]))
+      {
+        good_records_index = i;
+        break;
+      }
+    }
+    if (good_records_index >= 0) break;
+  }
+
+  if (good_records_index < 0)
+  {
+    LOG_PRINT_L0("WARNING: no two MoneroPulse DNS checkpoint records matched");
+    return false;
+  }
+
+  good_records = records[good_records_index];
+  return true;
+}
+
 }  // namespace tools::dns_utils
 
 }  // namespace tools
diff --git a/src/common/dns_utils.h b/src/common/dns_utils.h
index 6ecf5595c..2e881f0e0 100644
--- a/src/common/dns_utils.h
+++ b/src/common/dns_utils.h
@@ -165,6 +165,8 @@ std::vector<std::string> addresses_from_url(const std::string& url, bool& dnssec
 
 std::string get_account_address_as_str_from_url(const std::string& url, bool& dnssec_valid);
 
+bool load_txt_records_from_dns(std::vector<std::string> &records, const std::vector<std::string> &dns_urls);
+
 }  // namespace tools::dns_utils
 
 }  // namespace tools
diff --git a/src/common/download.cpp b/src/common/download.cpp
new file mode 100644
index 000000000..c5ee797d0
--- /dev/null
+++ b/src/common/download.cpp
@@ -0,0 +1,138 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <string>
+#include <boost/filesystem.hpp>
+#include <boost/asio.hpp>
+#include <boost/thread/thread.hpp>
+#include "cryptonote_config.h"
+#include "include_base_utils.h"
+#include "net/http_client.h"
+#include "download.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "net.dl"
+
+namespace tools
+{
+  static bool download_thread(const std::string &path, const std::string &url)
+  {
+    try
+    {
+      MINFO("Downloading " << url << " to " << path);
+      std::ofstream f;
+      f.open(path, std::ios_base::binary | std::ios_base::out | std::ios_base::trunc);
+      if (!f.good()) {
+        MERROR("Failed to open file " << path);
+        return false;
+      }
+      class download_client: public epee::net_utils::http::http_simple_client
+      {
+      public:
+        download_client(std::ofstream &f): f(f) {}
+        virtual ~download_client() { f.close(); }
+        virtual bool handle_target_data(std::string &piece_of_transfer)
+        {
+          try
+          {
+            f << piece_of_transfer;
+            return f.good();
+          }
+          catch (const std::exception &e)
+          {
+            MERROR("Error writing data: " << e.what());
+            return false;
+          }
+        }
+      private:
+        std::ofstream &f;
+      } client(f);
+      epee::net_utils::http::url_content u_c;
+      if (!epee::net_utils::parse_url(url, u_c))
+      {
+        MWARNING("Failed to parse URL " << url);
+        return false;
+      }
+      if (u_c.host.empty())
+      {
+        MWARNING("Failed to determine address from URL " << url);
+        return false;
+      }
+      uint16_t port = u_c.port ? u_c.port : 80;
+      MDEBUG("Connecting to " << u_c.host << ":" << port);
+      client.set_server(u_c.host, std::to_string(port), boost::none);
+      if (!client.connect(std::chrono::seconds(30)))
+      {
+        MERROR("Failed to connect to " << url);
+        return false;
+      }
+      MDEBUG("GETting " << u_c.uri);
+      const epee::net_utils::http::http_response_info *info = NULL;
+      if (!client.invoke_get(u_c.uri, std::chrono::seconds(30), "", &info))
+      {
+        MERROR("Failed to connect to " << url);
+        client.disconnect();
+        return false;
+      }
+      if (!info)
+      {
+        MERROR("Failed invoking GET command to " << url << ", no status info returned");
+        client.disconnect();
+        return false;
+      }
+      MDEBUG("response code: " << info->m_response_code);
+      MDEBUG("response comment: " << info->m_response_comment);
+      MDEBUG("response body: " << info->m_body);
+      for (const auto &f: info->m_additional_fields)
+        MDEBUG("additional field: " << f.first << ": " << f.second);
+      if (info->m_response_code != 200)
+      {
+        MERROR("Status code " << info->m_response_code);
+        client.disconnect();
+        return false;
+      }
+      client.disconnect();
+      f.close();
+      MDEBUG("Download complete");
+      return true;
+    }
+    catch (const std::exception &e)
+    {
+      MERROR("Exception in download thread: " << e.what());
+      return false;
+    }
+  }
+
+  bool download(const std::string &path, const std::string &url)
+  {
+    bool success;
+    std::unique_ptr<boost::thread> thread(new boost::thread([&](){ success = download_thread(path, url); }));
+    thread->join();
+    return success;
+  }
+}
diff --git a/src/common/download.h b/src/common/download.h
new file mode 100644
index 000000000..ab7644689
--- /dev/null
+++ b/src/common/download.h
@@ -0,0 +1,36 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once 
+
+#include <string>
+
+namespace tools
+{
+  bool download(const std::string &path, const std::string &url);
+}
diff --git a/src/common/updates.cpp b/src/common/updates.cpp
new file mode 100644
index 000000000..936106881
--- /dev/null
+++ b/src/common/updates.cpp
@@ -0,0 +1,114 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "util.h"
+#include "dns_utils.h"
+#include "updates.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "updates"
+
+namespace tools
+{
+  bool check_updates(const std::string &software, const std::string &buildtag, bool testnet, std::string &version, std::string &hash)
+  {
+    std::vector<std::string> records;
+    bool found = false;
+
+    MDEBUG("Checking updates for " << buildtag << " " << software);
+
+    // All four MoneroPulse domains have DNSSEC on and valid
+    static const std::vector<std::string> dns_urls = {
+    };
+
+    static const std::vector<std::string> testnet_dns_urls = { "testver.moneropulse.net"
+    };
+
+    if (!tools::dns_utils::load_txt_records_from_dns(records, testnet ? testnet_dns_urls : dns_urls))
+      return false;
+
+    for (const auto& record : records)
+    {
+      std::vector<std::string> fields;
+      boost::split(fields, record, boost::is_any_of(":"));
+      if (fields.size() != 4)
+      {
+        MWARNING("Updates record does not have 4 fields: " << record);
+        continue;
+      }
+
+      if (software != fields[0] || buildtag != fields[1])
+        continue;
+
+      bool alnum = true;
+      for (auto c: hash)
+        if (!isalnum(c))
+          alnum = false;
+      if (hash.size() != 64 && !alnum)
+      {
+        MWARNING("Invalid hash: " << hash);
+        continue;
+      }
+
+      // use highest version
+      if (found)
+      {
+        int cmp = vercmp(version.c_str(), fields[2].c_str());
+        if (cmp > 0)
+          continue;
+        if (cmp == 0 && hash != fields[3])
+          MWARNING("Two matches found for " << software << " version " << version << " on " << buildtag);
+      }
+
+      version = fields[2];
+      hash = fields[3];
+
+      MINFO("Found new version " << version << " with hash " << hash);
+      found = true;
+    }
+    return found;
+  }
+
+  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version)
+  {
+    static const char base[] = "https://downloads.getmonero.org/";
+#ifdef _WIN32
+    static const char extension[] = ".zip";
+#else
+    static const char extension[] = ".tar.bz2";
+#endif
+
+    std::string url;
+
+    url =  base;
+    if (!subdir.empty())
+      url += subdir + "/";
+    url = url + software + "-" + buildtag + "-v" + version + extension;
+    return url;
+  }
+}
diff --git a/src/common/updates.h b/src/common/updates.h
new file mode 100644
index 000000000..1a70e06fd
--- /dev/null
+++ b/src/common/updates.h
@@ -0,0 +1,37 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once 
+
+#include <string>
+
+namespace tools
+{
+  bool check_updates(const std::string &software, const std::string &buildtag, bool bestnet, std::string &version, std::string &hash);
+  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version);
+}
diff --git a/src/common/util.cpp b/src/common/util.cpp
index bfcf86bc6..90748ddb1 100644
--- a/src/common/util.cpp
+++ b/src/common/util.cpp
@@ -31,6 +31,7 @@
 #include <cstdio>
 
 #include "include_base_utils.h"
+#include "file_io_utils.h"
 using namespace epee;
 
 #include "util.h"
@@ -46,7 +47,7 @@ using namespace epee;
 #endif
 #include <boost/filesystem.hpp>
 #include <boost/asio.hpp>
-
+#include <openssl/sha.h>
 
 namespace tools
 {
@@ -568,4 +569,53 @@ std::string get_nix_version_display_string()
     MDEBUG("Address '" << address << "' is not local");
     return false;
   }
+  int vercmp(const char *v0, const char *v1)
+  {
+    std::vector<std::string> f0, f1;
+    boost::split(f0, v0, boost::is_any_of("."));
+    boost::split(f1, v1, boost::is_any_of("."));
+    while (f0.size() < f1.size())
+      f0.push_back("0");
+    while (f1.size() < f0.size())
+      f1.push_back("0");
+    for (size_t i = 0; i < f0.size(); ++i) {
+      int f0i = atoi(f0[i].c_str()), f1i = atoi(f1[i].c_str());
+      int n = f0i - f1i;
+      if (n)
+        return n;
+    }
+    return 0;
+  }
+
+  bool sha256sum(const std::string &filename, crypto::hash &hash)
+  {
+    if (!epee::file_io_utils::is_file_exist(filename))
+      return false;
+    std::ifstream f;
+    f.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+    f.open(filename, std::ios_base::binary | std::ios_base::in | std::ios::ate);
+    if (!f)
+      return false;
+    std::ifstream::pos_type file_size = f.tellg();
+    SHA256_CTX ctx;
+    if (!SHA256_Init(&ctx))
+      return false;
+    size_t size_left = file_size;
+    f.seekg(0, std::ios::beg);
+    while (size_left)
+    {
+      char buf[4096];
+      std::ifstream::pos_type read_size = size_left > sizeof(buf) ? sizeof(buf) : size_left;
+      f.read(buf, read_size);
+      if (!f || !f.good())
+        return false;
+      if (!SHA256_Update(&ctx, buf, read_size))
+        return false;
+      size_left -= read_size;
+    }
+    f.close();
+    if (!SHA256_Final((unsigned char*)hash.data, &ctx))
+      return false;
+    return true;
+  }
 }
diff --git a/src/common/util.h b/src/common/util.h
index c2ffc44ca..8ab469129 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -183,4 +183,7 @@ namespace tools
   unsigned get_max_concurrency();
 
   bool is_local_address(const std::string &address);
+  int vercmp(const char *v0, const char *v1); // returns < 0, 0, > 0, similar to strcmp, but more human friendly than lexical - does not attempt to validate
+
+  bool sha256sum(const std::string &filename, crypto::hash &hash);
 }
diff --git a/src/cryptonote_basic/checkpoints.cpp b/src/cryptonote_basic/checkpoints.cpp
index 3cf804ede..1e7754886 100644
--- a/src/cryptonote_basic/checkpoints.cpp
+++ b/src/cryptonote_basic/checkpoints.cpp
@@ -42,30 +42,6 @@ using namespace epee;
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "checkpoints"
 
-namespace
-{
-  bool dns_records_match(const std::vector<std::string>& a, const std::vector<std::string>& b)
-  {
-    if (a.size() != b.size()) return false;
-
-    for (const auto& record_in_a : a)
-    {
-      bool ok = false;
-      for (const auto& record_in_b : b)
-      {
-	if (record_in_a == record_in_b)
-	{
-	  ok = true;
-	  break;
-	}
-      }
-      if (!ok) return false;
-    }
-
-    return true;
-  }
-} // anonymous namespace
-
 namespace cryptonote
 {
   //---------------------------------------------------------------------------
@@ -230,6 +206,8 @@ namespace cryptonote
 
   bool checkpoints::load_checkpoints_from_dns(bool testnet)
   {
+    std::vector<std::string> records;
+
     // All four MoneroPulse domains have DNSSEC on and valid
     static const std::vector<std::string> dns_urls = { "checkpoints.moneropulse.se"
 						     , "checkpoints.moneropulse.org"
@@ -243,87 +221,10 @@ namespace cryptonote
 							     , "testpoints.moneropulse.co"
     };
 
-    std::vector<std::vector<std::string> > records;
-    records.resize(dns_urls.size());
-
-    std::random_device rd;
-    std::mt19937 gen(rd());
-    std::uniform_int_distribution<int> dis(0, dns_urls.size() - 1);
-    size_t first_index = dis(gen);
-
-    bool avail, valid;
-    size_t cur_index = first_index;
-    do
-    {
-      std::string url;
-      if (testnet)
-      {
-        url = testnet_dns_urls[cur_index];
-      }
-      else
-      {
-        url = dns_urls[cur_index];
-      }
-
-      records[cur_index] = tools::DNSResolver::instance().get_txt_record(url, avail, valid);
-      if (!avail)
-      {
-        records[cur_index].clear();
-        LOG_PRINT_L2("DNSSEC not available for checkpoint update at URL: " << url << ", skipping.");
-      }
-      if (!valid)
-      {
-        records[cur_index].clear();
-        LOG_PRINT_L2("DNSSEC validation failed for checkpoint update at URL: " << url << ", skipping.");
-      }
-
-      cur_index++;
-      if (cur_index == dns_urls.size())
-      {
-        cur_index = 0;
-      }
-      records[cur_index].clear();
-    } while (cur_index != first_index);
-
-    size_t num_valid_records = 0;
-
-    for( const auto& record_set : records)
-    {
-      if (record_set.size() != 0)
-      {
-        num_valid_records++;
-      }
-    }
-
-    if (num_valid_records < 2)
-    {
-      LOG_PRINT_L0("WARNING: no two valid MoneroPulse DNS checkpoint records were received");
-      return true;
-    }
-
-    int good_records_index = -1;
-    for (size_t i = 0; i < records.size() - 1; ++i)
-    {
-      if (records[i].size() == 0) continue;
-
-      for (size_t j = i + 1; j < records.size(); ++j)
-      {
-        if (dns_records_match(records[i], records[j]))
-        {
-    good_records_index = i;
-    break;
-        }
-      }
-      if (good_records_index >= 0) break;
-    }
-
-    if (good_records_index < 0)
-    {
-      LOG_PRINT_L0("WARNING: no two MoneroPulse DNS checkpoint records matched");
-      return true;
-    }
+    if (!tools::dns_utils::load_txt_records_from_dns(records, testnet ? testnet_dns_urls : dns_urls))
+      return true; // why true ?
 
-    for (auto& record : records[good_records_index])
+    for (const auto& record : records)
     {
       auto pos = record.find(":");
       if (pos != std::string::npos)
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index 239ef5d84..fd509b603 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -35,6 +35,8 @@ using namespace epee;
 #include "cryptonote_core.h"
 #include "common/command_line.h"
 #include "common/util.h"
+#include "common/updates.h"
+#include "common/download.h"
 #include "warnings.h"
 #include "crypto/crypto.h"
 #include "cryptonote_config.h"
@@ -148,6 +150,7 @@ namespace cryptonote
     command_line::add_arg(desc, command_line::arg_db_sync_mode);
     command_line::add_arg(desc, command_line::arg_show_time_stats);
     command_line::add_arg(desc, command_line::arg_block_sync_size);
+    command_line::add_arg(desc, command_line::arg_check_updates);
   }
   //-----------------------------------------------------------------------------------------------
   bool core::handle_command_line(const boost::program_options::variables_map& vm)
@@ -242,6 +245,7 @@ namespace cryptonote
     std::string db_sync_mode = command_line::get_arg(vm, command_line::arg_db_sync_mode);
     bool fast_sync = command_line::get_arg(vm, command_line::arg_fast_block_sync) != 0;
     uint64_t blocks_threads = command_line::get_arg(vm, command_line::arg_prep_blocks_threads);
+    std::string check_updates_string = command_line::get_arg(vm, command_line::arg_check_updates);
 
     boost::filesystem::path folder(m_config_folder);
     if (m_fakechain)
@@ -379,6 +383,20 @@ namespace cryptonote
     // with respect to what blocks we already have
     CHECK_AND_ASSERT_MES(update_checkpoints(), false, "One or more checkpoints loaded from json or dns conflicted with existing checkpoints.");
 
+   // DNS versions checking
+    if (check_updates_string == "disabled")
+      check_updates_level = UPDATES_DISABLED;
+    else if (check_updates_string == "notify")
+      check_updates_level = UPDATES_NOTIFY;
+    else if (check_updates_string == "download")
+      check_updates_level = UPDATES_DOWNLOAD;
+    else if (check_updates_string == "update")
+      check_updates_level = UPDATES_UPDATE;
+    else {
+      MERROR("Invalid argument to --dns-versions-check: " << check_updates_string);
+      return false;
+    }
+
     r = m_miner.init(vm, m_testnet);
     CHECK_AND_ASSERT_MES(r, false, "Failed to initialize miner instance");
 
@@ -599,6 +617,12 @@ namespace cryptonote
       return false;
     }
 
+    if (!check_tx_inputs_keyimages_domain(tx))
+    {
+      MERROR_VER("tx uses key image not in the valid domain");
+      return false;
+    }
+
     if (tx.version >= 2)
     {
       const rct::rctSig &rv = tx.rct_signatures;
@@ -682,6 +706,18 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::check_tx_inputs_keyimages_domain(const transaction& tx) const
+  {
+    std::unordered_set<crypto::key_image> ki;
+    for(const auto& in: tx.vin)
+    {
+      CHECKED_GET_SPECIFIC_VARIANT(in, const txin_to_key, tokey_in, false);
+      if (!(rct::scalarmultKey(rct::ki2rct(tokey_in.k_image), rct::curveOrder()) == rct::identity()))
+        return false;
+    }
+    return true;
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::add_new_tx(const transaction& tx, tx_verification_context& tvc, bool keeped_by_block, bool relayed, bool do_not_relay)
   {
     crypto::hash tx_hash = get_transaction_hash(tx);
@@ -1000,6 +1036,7 @@ namespace cryptonote
 
     m_fork_moaner.do_call(boost::bind(&core::check_fork_time, this));
     m_txpool_auto_relayer.do_call(boost::bind(&core::relay_txpool_transactions, this));
+    m_check_updates_interval.do_call(boost::bind(&core::check_updates, this));
     m_miner.on_idle();
     m_mempool.on_idle();
     return true;
@@ -1027,6 +1064,66 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::check_updates()
+  {
+    static const char software[] = "monerod";
+    static const char subdir[] = "cli"; // because it can never be simple
+#ifdef BUILD_TAG
+    static const char buildtag[] = BOOST_PP_STRINGIZE(BUILD_TAG);
+#else
+    static const char buildtag[] = "source";
+#endif
+
+    if (check_updates_level == UPDATES_DISABLED)
+      return true;
+
+    std::string version, hash;
+    MDEBUG("Checking for a new " << software << " version for " << buildtag);
+    if (!tools::check_updates(software, buildtag, m_testnet, version, hash))
+      return false;
+
+    if (tools::vercmp(version.c_str(), MONERO_VERSION) <= 0)
+      return true;
+
+    std::string url = tools::get_update_url(software, subdir, buildtag, version);
+    MGINFO("Version " << version << " of " << software << " for " << buildtag << " is available: " << url << ", SHA256 hash " << hash);
+
+    if (check_updates_level == UPDATES_NOTIFY)
+      return true;
+
+    std::string filename;
+    const char *slash = strrchr(url.c_str(), '/');
+    if (slash)
+      filename = slash + 1;
+    else
+      filename = std::string(software) + "-update-" + version;
+    boost::filesystem::path path(epee::string_tools::get_current_module_folder());
+    path /= filename;
+    if (!tools::download(path.string(), url))
+    {
+      MERROR("Failed to download " << url);
+      return false;
+    }
+    crypto::hash file_hash;
+    if (!tools::sha256sum(path.string(), file_hash))
+    {
+      MERROR("Failed to hash " << path);
+      return false;
+    }
+    if (hash != epee::string_tools::pod_to_hex(file_hash))
+    {
+      MERROR("Download from " << url << " does not match the expected hash");
+      return false;
+    }
+    MGINFO("New version downloaded to " << path);
+
+    if (check_updates_level == UPDATES_DOWNLOAD)
+      return true;
+
+    MERROR("Download/update not implemented yet");
+    return true;
+  }
+  //-----------------------------------------------------------------------------------------------
   void core::set_target_blockchain_height(uint64_t target_blockchain_height)
   {
     m_target_blockchain_height = target_blockchain_height;
diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h
index 1463c2feb..43435b0c3 100644
--- a/src/cryptonote_core/cryptonote_core.h
+++ b/src/cryptonote_core/cryptonote_core.h
@@ -745,6 +745,16 @@ namespace cryptonote
      bool check_tx_inputs_keyimages_diff(const transaction& tx) const;
 
      /**
+      * @brief verify that each input key image in a transaction is in
+      * the valid domain
+      *
+      * @param tx the transaction to check
+      *
+      * @return false if any key image is not in the valid domain, otherwise true
+      */
+     bool check_tx_inputs_keyimages_domain(const transaction& tx) const;
+
+     /**
       * @brief checks HardFork status and prints messages about it
       *
       * Checks the status of HardFork and logs/prints if an update to
@@ -763,6 +773,13 @@ namespace cryptonote
       */
      bool relay_txpool_transactions();
 
+     /**
+      * @brief checks DNS versions
+      *
+      * @return true on success, false otherwise
+      */
+     bool check_updates();
+
      bool m_test_drop_download = true; //!< whether or not to drop incoming blocks (for testing)
 
      uint64_t m_test_drop_download_height = 0; //!< height under which to drop incoming blocks, if doing so
@@ -783,8 +800,9 @@ namespace cryptonote
      cryptonote_protocol_stub m_protocol_stub; //!< cryptonote protocol stub instance
 
      epee::math_helper::once_a_time_seconds<60*60*12, false> m_store_blockchain_interval; //!< interval for manual storing of Blockchain, if enabled
-     epee::math_helper::once_a_time_seconds<60*60*2, false> m_fork_moaner; //!< interval for checking HardFork status
+     epee::math_helper::once_a_time_seconds<60*60*2, true> m_fork_moaner; //!< interval for checking HardFork status
      epee::math_helper::once_a_time_seconds<60*2, false> m_txpool_auto_relayer; //!< interval for checking re-relaying txpool transactions
+     epee::math_helper::once_a_time_seconds<60*60*12, true> m_check_updates_interval; //!< interval for checking for new versions
 
      friend class tx_validate_inputs;
      std::atomic<bool> m_starter_message_showed; //!< has the "daemon will sync now" message been shown?
@@ -808,6 +826,13 @@ namespace cryptonote
      time_t start_time;
 
      std::unordered_set<crypto::hash> bad_semantics_txes;
+
+     enum {
+       UPDATES_DISABLED,
+       UPDATES_NOTIFY,
+       UPDATES_DOWNLOAD,
+       UPDATES_UPDATE,
+     } check_updates_level;
    };
 }
 
diff --git a/src/ringct/rctOps.h b/src/ringct/rctOps.h
index 90f54b050..cb19bbbd6 100644
--- a/src/ringct/rctOps.h
+++ b/src/ringct/rctOps.h
@@ -66,6 +66,7 @@ namespace rct {
 
     static const key Z = { {0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00  } };
     static const key I = { {0x01, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00  } };
+    static const key L = { {0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10 } };
 
     //Creates a zero scalar
     inline key zero() { return Z; }
@@ -73,6 +74,9 @@ namespace rct {
     //Creates a zero elliptic curve point
     inline key identity() { return I; }
     inline void identity(key &Id) { memcpy(&Id, &I, 32); }
+    //Creates a key equal to the curve order
+    inline key curveOrder() { return L; }
+    inline void curveOrder(key &l) { l = L; }
     //copies a scalar or point
     inline void copy(key &AA, const key &A) { memcpy(&AA, &A, 32); }
     inline key copy(const key & A) { key AA; memcpy(&AA, &A, 32); return AA; }
diff --git a/tests/unit_tests/CMakeLists.txt b/tests/unit_tests/CMakeLists.txt
index e70ed1a24..04e47e49b 100644
--- a/tests/unit_tests/CMakeLists.txt
+++ b/tests/unit_tests/CMakeLists.txt
@@ -58,7 +58,8 @@ set(unit_tests_sources
   uri.cpp
   varint.cpp
   ringct.cpp
-  output_selection.cpp)
+  output_selection.cpp
+  vercmp.cpp)
 
 set(unit_tests_headers
   unit_tests_utils.h)
diff --git a/tests/unit_tests/vercmp.cpp b/tests/unit_tests/vercmp.cpp
new file mode 100644
index 000000000..d48dfdf7c
--- /dev/null
+++ b/tests/unit_tests/vercmp.cpp
@@ -0,0 +1,43 @@
+// Copyright (c) 2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "gtest/gtest.h"
+
+#include "common/util.h"
+
+TEST(vercmp, empty) { ASSERT_TRUE(tools::vercmp("", "") == 0); }
+TEST(vercmp, empty0) { ASSERT_TRUE(tools::vercmp("", "0") == 0); }
+TEST(vercmp, empty1) { ASSERT_TRUE(tools::vercmp("0", "") == 0); }
+TEST(vercmp, zero_zero) { ASSERT_TRUE(tools::vercmp("0", "0") == 0); }
+TEST(vercmp, one_one) { ASSERT_TRUE(tools::vercmp("1", "1") == 0); }
+TEST(vercmp, one_two) { ASSERT_TRUE(tools::vercmp("1", "2") < 0); }
+TEST(vercmp, two_one) { ASSERT_TRUE(tools::vercmp("2", "1") > 0); }
+TEST(vercmp, ten_nine) { ASSERT_TRUE(tools::vercmp("10", "9") > 0); }
+TEST(vercmp, one_dot_ten_one_dot_nine) { ASSERT_TRUE(tools::vercmp("1.10", "1.9") > 0); }
+TEST(vercmp, one_one_dot_nine) { ASSERT_TRUE(tools::vercmp("1", "1.9") < 0); }
+