C# Method to verify whether user input information contains dangerous strings

This article example describes the method of C# to verify whether the user input information contains dangerous strings. Share it for your reference. The specific analysis is as follows:

This C# function can be used for back-end verification of form input data, and determine whether the user has submitted some dangerous injected characters related to SQL.

/// &lt;summary&gt;
/// Check whether the string entered by the client is valid and modify the original string to a valid string or an empty string/// When an offensive and dangerous string is detected in the client's input, it returns false and returns true effectively./// &lt;/summary&gt;
/// <param name="input">String to be detected</param>public static bool IsValidInput(ref string input)
{
  try
  {
 if (IsNullOrEmpty(input))
 {
   //If it is a null value, it will jump out   return true;
 }
 else
 {
   //Replace single quotes   input = ("'", "''").Trim();

   //Detection of aggressive hazard string   string testString = "and |or |exec |insert |select |delete |update |count |chr |mid |master |truncate |char |declare ";
   string[] testArray = ('|');
   foreach (string testStr in testArray)
   {
 if (().IndexOf(testStr) != -1)
 {
   //Attack string is detected and clear the passed value   input = "";
   return false;
 }
   }
   //The attack string was not detected   return true;
 }
  }
  catch (Exception ex)
  {
 throw new Exception();
  }
}

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