The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,676 other followers

Archive for September 21st, 2017

Don’t Use Regular Expressions To Parse IP Addresses!

Posted by jpluimers on 2017/09/21

Interesting piece: Don’t Use Regular Expressions To Parse IP Addresses! [WayBack]

TL;DR:

When have neither then for quad-dotted decimal IPv4 addresses (ignoring for instance octals and grouped quads), this is suitable: regex – Regular expression to match DNS hostname or IP Address? – Stack Overflow [WayBack]

ValidIpAddressRegex = "^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$";

Which explained looks like this:

https://regex101.com/r/Wyr2Zd/1

Regular expression:

/ ^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$ / g

Explanation:

  • ^ asserts position at start of the string
    • 1st Capturing Group (([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}
      • {3} Quantifier — Matches exactly 3 times
        A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you’re not interested in the data

        • 2nd Capturing Group ([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])
          • 1st Alternative [0-9]
            • Match a single character present in the list below [0-9]
              0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
          • 2nd Alternative [1-9][0-9]
            • Match a single character present in the list below [1-9]
              1-9 a single character in the range between 1 (ASCII 49) and 9 (ASCII 57) (case sensitive)
            • Match a single character present in the list below [0-9]
              0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
          • 3rd Alternative 1[0-9]{2}
            • 1 matches the character 1 literally (case sensitive)
            • Match a single character present in the list below [0-9]{2}
              {2} Quantifier — Matches exactly 2 times
              0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
          • 4th Alternative 2[0-4][0-9]
            • 2 matches the character 2 literally (case sensitive)
            • Match a single character present in the list below [0-4]
              0-4 a single character in the range between 0 (ASCII 48) and 4 (ASCII 52) (case sensitive)
            • Match a single character present in the list below [0-9]
              0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
          • 5th Alternative 25[0-5]
            • 25 matches the characters 25 literally (case sensitive)
            • Match a single character present in the list below [0-5]
              0-5 a single character in the range between 0 (ASCII 48) and 5 (ASCII 53) (case sensitive)
        • \. matches the character . literally (case sensitive)
    • 3rd Capturing Group ([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])
      • 1st Alternative [0-9]
        • Match a single character present in the list below [0-9]
          0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
      • 2nd Alternative [1-9][0-9]
        • Match a single character present in the list below [1-9]
          1-9 a single character in the range between 1 (ASCII 49) and 9 (ASCII 57) (case sensitive)
        • Match a single character present in the list below [0-9]
          0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
      • 3rd Alternative 1[0-9]{2}
        • 1 matches the character 1 literally (case sensitive)
        • Match a single character present in the list below [0-9]{2}
          {2} Quantifier — Matches exactly 2 times
          0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
      • 4th Alternative 2[0-4][0-9]
        • 2 matches the character 2 literally (case sensitive)
        • Match a single character present in the list below [0-4]
          0-4 a single character in the range between 0 (ASCII 48) and 4 (ASCII 52) (case sensitive)
        • Match a single character present in the list below [0-9]
          0-9 a single character in the range between 0 (ASCII 48) and 9 (ASCII 57) (case sensitive)
      • 5th Alternative 25[0-5]
        • 25 matches the characters 25 literally (case sensitive)
        • Match a single character present in the list below [0-5]
          0-5 a single character in the range between 0 (ASCII 48) and 5 (ASCII 53) (case sensitive)
  • $ asserts position at the end of the string, or before the line terminator right at the end of the string (if any)
  • Global pattern flags
    g modifier: global. All matches (don’t return after first match)

–jeroen

Posted in *nix, Communications Development, Development, Internet protocol suite, Network-and-equipment, Power User, Software Development, TCP | Leave a Comment »

Mikrotik functions -> hopefully I can translate this to the new syntax

Posted by jpluimers on 2017/09/21

Reminder to self as it would be useful to have these Mikrotik functions in the new function syntax:

–jeroen

Posted in Internet, MikroTik, Power User, Routers | Leave a Comment »

 
%d bloggers like this: