CODEWITHSUNDEEP
c#.netregex
Maddy
Maddy

Reputation: 590

Regex: Check IP address against user input with wildcard

I have a list named IpAddressList with some IP addresses like 192.168.0.5 and so on.

The user can search the list for a given IP address, also by using the wildcard *

This is my method:

public bool IpAddressMatchUserInput(String userInput, String ipAddressFromList)
{
    Regex regex = new Regex("");

    Match match = regex.Match(ipAddressFromList);

    return match.Success;
}

The userInput can be for example:

In all cases the method should return true, but I don't know how to use Regex in combination with the userInputand how the regex should look.

Upvotes: 1

Views: 1096

Answers (2)

Dirk Vollmar
Dirk Vollmar

Reputation: 176169

Here's a more robust version that does not break if the user input contains Regex metacharacters such as \, or unmatched parenthesis:

public static bool IpAddressMatchUserInput(string userInput, string ipAddressFromList)
{
    // escape the user input. If user input contains e.g. an unescaped 
    // single backslash we might get an ArgumentException when not escaping
    var escapedInput = Regex.Escape(userInput);

    // replace the wildcard '*' with a regex pattern matching 1 to 3 digits
    var inputWithWildcardsReplaced = escapedInput.Replace("\\*", @"\d{1,3}");

    // require the user input to match at the beginning of the provided IP address
    var pattern = new Regex("^" + inputWithWildcardsReplaced);

    return pattern.IsMatch(ipAddressFromList);
}

Upvotes: 0

Zein Makki
Zein Makki

Reputation: 30022

I think this should work (covering also 192.*.0.*):

public static bool IpAddressMatchUserInput(String userInput, String ipAddressFromList)
{
    Regex rg = new Regex(userInput.Replace("*", @"\d{1,3}").Replace(".", @"\."));

    return rg.IsMatch(ipAddressFromList);
}

Upvotes: 4

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