Masking: Add parameter for warnings

The masking filter can now be instructed to warn in case a masking
rule matches a column of a type that is not masked.

Documentation/Filters/Masking.md

@@ -76,7 +76,7 @@ type=service
 filters=Mask-SSN
 ```
 
-# Filter Parameter
+## Filter Parameters
 
 The masking filter has one mandatory parameter - `rules_file`.
 
@@ -90,6 +90,18 @@ MariaDB MaxScale.
 rules_file=/path/to/rules-file
 ```
 
+#### `warn_type_mismatch`
+
+With this optional parameter the masking filter can be instructed to log
+a warning if a masking rule matches a column that is not of one of the
+allowed types.
+
+The values that can be used are `never` and `always`, with `never` being
+the default.
+```
+warn_type_mismatch=always
+```
+
 # Rules
 
 The masking rules are expressed as a JSON object.

server/modules/filter/masking/CMakeLists.txt

@@ -1,6 +1,7 @@
 if (JANSSON_FOUND)
   add_library(masking SHARED
     maskingfilter.cc
+    maskingfilterconfig.cc
     maskingfiltersession.cc
     maskingrules.cc
     )

server/modules/filter/masking/maskingfilter.cc

@@ -77,6 +77,8 @@ extern "C" MXS_MODULE* MXS_CREATE_MODULE()
 
     MXS_NOTICE("Masking module %s initialized.", VERSION_STRING);
 
+    typedef MaskingFilter::Config Config;
+
     static MXS_MODULE info =
     {
         MXS_MODULE_API_FILTER,
@@ -90,7 +92,10 @@ extern "C" MXS_MODULE* MXS_CREATE_MODULE()
         NULL, /* Thread init. */
         NULL, /* Thread finish. */
         {
-            {"rules_file", MXS_MODULE_PARAM_STRING, NULL, MXS_MODULE_OPT_REQUIRED},
+            { Config::rules_file_name, MXS_MODULE_PARAM_STRING, NULL, MXS_MODULE_OPT_REQUIRED },
+            { Config::warn_type_mismatch_name,
+              MXS_MODULE_PARAM_ENUM, Config::warn_type_mismatch_default,
+              MXS_MODULE_OPT_NONE, Config::warn_type_mismatch_values },
             { MXS_END_MODULE_PARAMS }
         }
     };
@@ -114,12 +119,15 @@ MaskingFilter::~MaskingFilter()
 }
 
 // static
-MaskingFilter* MaskingFilter::create(const char* zName, char** pzOptions, CONFIG_PARAMETER* ppParams)
+MaskingFilter* MaskingFilter::create(const char* zName, char** pzOptions, CONFIG_PARAMETER* pParams)
 {
     MaskingFilter* pFilter = NULL;
 
     MaskingFilter::Config config(zName);
-    process_params(pzOptions, ppParams, config);
+
+    config.set_warn_type_mismatch(Config::get_warn_type_mismatch(pParams));
+    process_params(pzOptions, pParams, config);
+
     auto_ptr<MaskingRules> sRules = MaskingRules::load(config.rules_file().c_str());
 
     if (sRules.get())

server/modules/filter/masking/maskingfilter.hh

@@ -39,6 +39,7 @@ public:
 
     void reload(DCB* pOut);
 
+    const Config& config() const { return m_config; }
     SMaskingRules rules() const;
 
 private:

server/modules/filter/masking/maskingfilterconfig.cc

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include "maskingfilterconfig.hh"
+
+namespace
+{
+
+const char config_name_rules_file[]          = "rules_file";
+const char config_name_warn_type_mismatch[]  = "warn_type_mismatch";
+
+const char config_value_never[]  = "never";
+const char config_value_always[] = "always";
+
+}
+
+//static
+const char* MaskingFilterConfig::rules_file_name = config_name_rules_file;
+
+
+//static
+const char* MaskingFilterConfig::warn_type_mismatch_name = config_name_warn_type_mismatch;
+
+//static
+const MXS_ENUM_VALUE MaskingFilterConfig::warn_type_mismatch_values[] =
+{
+    { config_value_never,  MaskingFilterConfig::WARN_NEVER },
+    { config_value_always, MaskingFilterConfig::WARN_ALWAYS },
+    { NULL }
+};
+
+//static
+const char* MaskingFilterConfig::warn_type_mismatch_default = config_value_never;
+
+
+//static
+MaskingFilterConfig::warn_type_mismatch_t
+MaskingFilterConfig::get_warn_type_mismatch(const CONFIG_PARAMETER* pParams)
+{
+    int warn = config_get_enum(pParams, warn_type_mismatch_name, warn_type_mismatch_values);
+    return static_cast<warn_type_mismatch_t>(warn);
+}

server/modules/filter/masking/maskingfilterconfig.hh

@@ -13,22 +13,42 @@
  */
 
 #include <maxscale/cppdefs.hh>
+#include <maxscale/config.h>
+#include <maxscale/modinfo.h>
 #include <string>
 
 class MaskingFilterConfig
 {
 public:
+    enum warn_type_mismatch_t
+    {
+        WARN_NEVER,
+        WARN_ALWAYS
+    };
+
+    static const char*          rules_file_name;
+
+    static const char*          warn_type_mismatch_name;
+    static const MXS_ENUM_VALUE warn_type_mismatch_values[];
+    static const char*          warn_type_mismatch_default;
+
     MaskingFilterConfig(const char* zName)
         : m_name(zName)
+        , m_warn_type_mismatch(WARN_NEVER)
     {}
     ~MaskingFilterConfig() {}
 
     const std::string&   name() const { return m_name; }
     const std::string&   rules_file() const { return m_rules_file; }
+    warn_type_mismatch_t warn_type_mismatch() const { return m_warn_type_mismatch; }
 
     void set_rules_file(const std::string& s) { m_rules_file = s; }
+    void set_warn_type_mismatch(warn_type_mismatch_t w) { m_warn_type_mismatch = w; }
+
+    static warn_type_mismatch_t get_warn_type_mismatch(const CONFIG_PARAMETER* pParams);
 
 private:
     std::string          m_name;
     std::string          m_rules_file;
+    warn_type_mismatch_t m_warn_type_mismatch;
 };

server/modules/filter/masking/maskingfiltersession.cc

@@ -178,6 +178,17 @@ void MaskingFilterSession::handle_eof(GWBUF* pPacket)
     }
 }
 
+namespace
+{
+
+void warn_of_type_mismatch(const MaskingRules::Rule& rule)
+{
+    MXS_WARNING("The rule targeting \"%s\" matches a column "
+                "that is not of string type.", rule.match().c_str());
+}
+
+}
+
 void MaskingFilterSession::handle_row(GWBUF* pPacket)
 {
     MXS_NOTICE("handle_row");
@@ -213,7 +224,10 @@ void MaskingFilterSession::handle_row(GWBUF* pPacket)
                             LEncString s = value.as_string();
                             pRule->rewrite(s);
                         }
-
+                        else if (m_filter.config().warn_type_mismatch() == Config::WARN_ALWAYS)
+                        {
+                            warn_of_type_mismatch(*pRule);
+                        }
                     }
                     ++i;
                 }
@@ -238,6 +252,10 @@ void MaskingFilterSession::handle_row(GWBUF* pPacket)
                             LEncString s = value.as_string();
                             pRule->rewrite(s);
                         }
+                        else if (m_filter.config().warn_type_mismatch() == Config::WARN_ALWAYS)
+                        {
+                            warn_of_type_mismatch(*pRule);
+                        }
                     }
                     ++i;
                 }

server/modules/filter/masking/maskingfiltersession.hh

@@ -20,10 +20,13 @@
 #include "maskingrules.hh"
 
 class MaskingFilter;
+class MaskingFilterConfig;
 
 class MaskingFilterSession : public maxscale::FilterSession
 {
 public:
+    typedef MaskingFilterConfig Config;
+
     ~MaskingFilterSession();
 
     static MaskingFilterSession* create(SESSION* pSession, const MaskingFilter* pFilter);

server/modules/filter/masking/maskingrules.cc

@@ -614,6 +614,19 @@ auto_ptr<MaskingRules::Rule> MaskingRules::Rule::create_from(json_t* pRule)
     return sRule;
 }
 
+string MaskingRules::Rule::match() const
+{
+    string s;
+
+    s += m_database.empty() ? "*" : m_database;
+    s += ".";
+    s += m_table.empty() ? "*" : m_table;
+    s += ".";
+    s += m_column;
+
+    return s;
+}
+
 namespace
 {
 

server/modules/filter/masking/maskingrules.hh

@@ -88,6 +88,8 @@ public:
              const std::vector<SAccount>& exempted);
         ~Rule();
 
+        std::string match() const;
+
         const std::string& column() const { return m_column; }
         const std::string& table() const { return m_table; }
         const std::string& database() const { return m_database; }