DDM ruleId validation

Author: yoavrubin

src/ResourceManager/Sql/Commands.Sql/Properties/Resources.Designer.cs

@@ -231,4 +231,7 @@
   <data name="DeprecatedCmdletUsageWarning" xml:space="preserve">
     <value>The {0} cmdlet is deprecated and will be removed in a future release.</value>
   </data>
+  <data name="NewDataMaskingRuleIdIsNotValid" xml:space="preserve">
+    <value>Rule Id cannot contain '&lt;,&gt;,+,=,#,*,%,&amp;,\,/,?' and cannot end with a '.'</value>
+  </data>
 </root>

src/ResourceManager/Sql/Commands.Sql/Properties/Resources.resx

@@ -19,6 +19,7 @@
 using System.Globalization;
 using System.Linq;
 using System.Management.Automation;
+using System.Text.RegularExpressions;
 
 namespace Microsoft.Azure.Commands.Sql.Security.Cmdlet.DataMasking
 {
@@ -66,6 +67,12 @@ protected override IEnumerable<DatabaseDataMaskingRuleModel> GetEntity()
         /// <returns>An error message or null if all is fine</returns>
         protected override string ValidateOperation(IEnumerable<DatabaseDataMaskingRuleModel> rules)
         {
+            var ruleIdRegex = new Regex("^[^/\\\\#+=<>*%&:?]*[^/\\\\#+=<>*%&:?.]$");
+            
+            if (!ruleIdRegex.IsMatch(RuleId)) // an invalid rule name
+            {
+                return string.Format(CultureInfo.InvariantCulture, Resources.NewDataMaskingRuleIdIsNotValid, RuleId);
+            }
             if(rules.Any(r=> r.RuleId == RuleId))
             {
                 return string.Format(CultureInfo.InvariantCulture, Resources.NewDataMaskingRuleIdAlreadyExistError, RuleId);