When there is a new CryFS version, ask the user to update. Furthermore, check if there is a security warning for the installed CryFS version.

CMakeLists.txt

@@ -12,6 +12,8 @@ ADD_BOOST(program_options chrono)
 
 ADD_DEFINITIONS(-D_FILE_OFFSET_BITS=64)
 
+TARGET_LINK_LIBRARIES(${BII_BLOCK_TARGET} INTERFACE curl)
+
 GIT_VERSION_INIT()
 
 ENABLE_STYLE_WARNINGS()

src/cli/Cli.cpp

@@ -18,6 +18,8 @@
 
 #include <gitversion/version.h>
 
+#include "VersionChecker.h"
+
 #include <pwd.h>
 
 //<limits.h> needed for libc to define PASS_MAX
@@ -79,12 +81,23 @@ namespace cryfs {
         } else if (!version::IS_STABLE_VERSION) {
             cout << "WARNING! This is an experimental version. Please backup your data frequently!" << endl;
         } else {
-            //TODO This is shown for stable version numbers like 0.8 - remove once we reach 1.0
+            //TODO This is even shown for stable version numbers like 0.8 - remove once we reach 1.0
             cout << "WARNING! This version is not considered stable. Please backup your data frequently!" << endl;
         }
 #ifndef NDEBUG
         cout << "WARNING! This is a debug build. Performance might be slow." << endl;
 #endif
+        VersionChecker versionChecker;
+        optional<string> newestVersion = versionChecker.newestVersion();
+        if (newestVersion == none) {
+            cout << "Could not connect to cryfs.org to check for updates." << endl;
+        } else if (*newestVersion != version::VERSION_STRING) {
+            cout << "CryFS " << *newestVersion << " is released. Please update." << endl;
+        }
+        optional<string> securityWarning = versionChecker.securityWarningFor(version::VERSION_STRING);
+        if (securityWarning != none) {
+            cout << *securityWarning << endl;
+        }
         cout << endl;
     }
 

src/cli/HttpClient.cpp

@@ -0,0 +1,50 @@
+// Base version taken from https://techoverflow.net/blog/2013/03/15/c-simple-http-download-using-libcurl-easy-api/
+/**
+ * HTTPDownloader.cpp
+ *
+ * A simple C++ wrapper for the libcurl easy API.
+ *
+ * Written by Uli Köhler (techoverflow.net)
+ * Published under CC0 1.0 Universal (public domain)
+ */
+#include "HttpClient.h"
+#include <sstream>
+#include <iostream>
+#include <curl/curl.h>
+#include <curl/easy.h>
+
+using boost::none;
+using boost::optional;
+using std::string;
+using std::ostringstream;
+
+size_t HttpClient::write_data(void *ptr, size_t size, size_t nmemb, ostringstream *stream) {
+    stream->write((const char*)ptr, size*nmemb);
+    return size * nmemb;
+}
+
+HttpClient::HttpClient() {
+    curl = curl_easy_init();
+}
+
+HttpClient::~HttpClient() {
+    curl_easy_cleanup(curl);
+}
+
+optional<string> HttpClient::get(const string& url) {
+    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
+    // example.com is redirected, so we tell libcurl to follow redirection
+    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1); //Prevent "longjmp causes uninitialized stack frame" bug
+    curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "deflate");
+    ostringstream out;
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpClient::write_data);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &out);
+    // Perform the request, res will get the return code
+    CURLcode res = curl_easy_perform(curl);
+    // Check for errors
+    if (res != CURLE_OK) {
+        return none;
+    }
+    return out.str();
+}

src/cli/HttpClient.h

@@ -0,0 +1,41 @@
+// Base version taken from https://techoverflow.net/blog/2013/03/15/c-simple-http-download-using-libcurl-easy-api/
+/**
+ * HTTPDownloader.hpp
+ *
+ * A simple C++ wrapper for the libcurl easy API.
+ *
+ * Written by Uli Köhler (techoverflow.net)
+ * Published under CC0 1.0 Universal (public domain)
+ */
+#pragma once
+#ifndef MESSMER_CRYFS_SRC_CLI_HTTPCLIENT_HPP
+#define MESSMER_CRYFS_SRC_CLI_HTTPCLIENT_HPP
+
+#include <string>
+#include <boost/optional.hpp>
+#include <messmer/cpp-utils/macros.h>
+
+//TODO Test
+
+/**
+ * A non-threadsafe simple libcURL-easy based HTTP downloader
+ */
+class HttpClient final {
+public:
+    HttpClient();
+    ~HttpClient();
+    /**
+     * Download a file using HTTP GET and store in in a std::string
+     * @param url The URL to download
+     * @return The download result
+     */
+    boost::optional<std::string> get(const std::string& url);
+private:
+    void* curl;
+
+    static size_t write_data(void *ptr, size_t size, size_t nmemb, std::ostringstream *stream);
+
+    DISALLOW_COPY_AND_ASSIGN(HttpClient);
+};
+
+#endif

src/cli/VersionChecker.cpp

@@ -0,0 +1,65 @@
+#include "VersionChecker.h"
+#include <sstream>
+#include "HttpClient.h"
+#include <boost/property_tree/json_parser.hpp>
+#include <messmer/cpp-utils/logging/logging.h>
+#include <boost/foreach.hpp>
+
+using boost::optional;
+using boost::none;
+using std::string;
+using boost::property_tree::ptree;
+using boost::property_tree::json_parser_error;
+using namespace cpputils::logging;
+
+#include <iostream>
+namespace cryfs {
+
+    VersionChecker::VersionChecker(): _versionInfo(_getVersionInfo()) {
+    }
+
+    optional<string> VersionChecker::newestVersion() const {
+        if (_versionInfo == none) {
+            return none;
+        }
+        string version = _versionInfo->get("version_info.current", "");
+        if (version == "") {
+            return none;
+        }
+        return version;
+    }
+
+    optional<string> VersionChecker::securityWarningFor(const string &version) const {
+        if (_versionInfo == none) {
+            return none;
+        }
+        BOOST_FOREACH(const ptree::value_type &v, _versionInfo->get_child("warnings")) {
+            if(v.first == version) {
+                return v.second.get_value<std::string>();
+            }
+        }
+        return none;
+    }
+
+    optional<ptree> VersionChecker::_getVersionInfo() {
+        optional<string> response = HttpClient().get("http://www.cryfs.org/version_info.json");
+        if (response == none) {
+            std::cout << "no response" << std::endl;
+            return none;
+        }
+        return _parseJson(*response);
+    }
+
+    optional<ptree> VersionChecker::_parseJson(const string &json) {
+        try {
+            ptree pt;
+            std::istringstream input(json);
+            read_json(input, pt);
+            return pt;
+        } catch (const json_parser_error &e) {
+            LOG(WARN) << "Error parsing version information json object";
+            return none;
+        }
+    }
+
+}

src/cli/VersionChecker.h

@@ -0,0 +1,28 @@
+#ifndef MESSMER_CRYFS_SRC_CLI_VERSIONCHECKER_H
+#define MESSMER_CRYFS_SRC_CLI_VERSIONCHECKER_H
+
+#include <messmer/cpp-utils/macros.h>
+#include <string>
+#include <boost/optional.hpp>
+#include <boost/property_tree/ptree.hpp>
+
+namespace cryfs {
+    //TODO Test
+
+    class VersionChecker final {
+    public:
+        VersionChecker();
+
+        boost::optional<std::string> newestVersion() const;
+        boost::optional<std::string> securityWarningFor(const std::string &version) const;
+    private:
+        static boost::optional<boost::property_tree::ptree> _getVersionInfo();
+        static boost::optional<boost::property_tree::ptree> _parseJson(const std::string &json);
+
+        boost::optional<boost::property_tree::ptree> _versionInfo;
+
+        DISALLOW_COPY_AND_ASSIGN(VersionChecker);
+    };
+}
+
+#endif