Can I improve this regex check for valid domain names?

Posted by Josh on Stack Overflow See other posts from Stack Overflow or by Josh
Published on 2008-12-30T10:22:13Z Indexed on 2010/05/17 19:40 UTC
Read the original article Hit count: 343

Filed under:

domain

|

regex

|

whois

|

dns

So, I have been working on this domain name regular expression. So far, it seems to pick up domain names with SLDs and TLDs (with the optional ccTLD), but there is duplication of the TLD listing. Can this be refactored any further?

params[:domain_name].downcase.strip.match(/^[a-z0-9\-]{2,63}
\.((a[cdefgilmnoqrstuwxz]|aero|arpa)|(b[abdefghijmnorstvwyz]|biz)|
(c[acdfghiklmnorsuvxyz]|cat|com|coop)|d[ejkmoz]|(e[ceghrstu]|edu)|f[ijkmor]|
(g[abdefghilmnpqrstuwy]|gov)|h[kmnrtu]|(i[delmnoqrst]|info|int)|
(j[emop]|jobs)|k[eghimnprwyz]|l[abcikrstuvy]|
(m[acdghklmnopqrstuvwxyz]|me|mil|mobi|museum)|(n[acefgilopruz]|name|net)|(om|org)|
(p[aefghklmnrstwy]|pro)|qa|r[eouw]|s[abcdeghijklmnortvyz]|
(t[cdfghjklmnoprtvwz]|travel)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw])
(\.((a[cdefgilmnoqrstuwxz]|aero|arpa)|(b[abdefghijmnorstvwyz]|biz)|
(c[acdfghiklmnorsuvxyz]|cat|com|coop)|d[ejkmoz]|(e[ceghrstu]|edu)|f[ijkmor]|
(g[abdefghilmnpqrstuwy]|gov)|h[kmnrtu]|(i[delmnoqrst]|info|int)|
(j[emop]|jobs)|k[eghimnprwyz]|l[abcikrstuvy]|
m[acdghklmnopqrstuvwxyz]|mil|mobi|museum)|
(n[acefgilopruz]|name|net)|(om|org)|
(p[aefghklmnrstwy]|pro)|qa|r[eouw]|s[abcdeghijklmnortvyz]|
(t[cdfghjklmnoprtvwz]|travel)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw]))?$/)

© Stack Overflow or respective owner

Related posts about domain

In WHM - Addon Domain Matches Primary Domain From Separate Account - I can't delete the addon domain

as seen on Server Fault - Search for 'Server Fault'
I have an account (domian1.com) with the an addon domain (domain2.com) that matches the primary domain (domain2.com) of a separate account. I believe it was created renaming the primary domain of the second account. I want to delete the addon domain from domain1.com. However when I try i get the error: … >>> More
Trust my work domain on a Dev Domain without a domain level password

as seen on Server Fault - Search for 'Server Fault'
I setup a virtual machine to host a dev version of TFS (to test plugins on). Getting a computer on my work domain requires large amounts of red tape and paperwork that I would rather not do. I created my own domain the the VM and I would like to trust all users from my work domain on that VM Domain… >>> More
NFS (with Kerberos) mount failing due to "Server not found in Kerberos database" error

as seen on Server Fault - Search for 'Server Fault'
When running: `sudo mount -t nfs4 -o sec=krb5 sol.domain.com:/ /mnt` I get this error on the client: mount.nfs4: access denied by server while mounting sol.domain.com:/ And on the server syslogs UNKNOWN_SERVER: authtime 0, nfs/mercury.domain.com@SOL.DOMAIN.COM for nfs/ip-#-#-#-#.ec2.internal@SOL… >>> More
Server 2003 on domain wont let domain user have local profile

as seen on Server Fault - Search for 'Server Fault'
I have a few servers that are acting in this behavior, you log in and always get put into a temporary profile. The server is licensed for TS. The user I am testing with has local admin rights so it doesn't seem to be a permission issue on the server. I'll first get a message that the users roaming… >>> More
Problem with redirecting *.domain.com & domain.com to www.domain.com for HTTPS

as seen on Stack Overflow - Search for 'Stack Overflow'
We have a site I'll call acme.com. Most of the time you see http://www.acme.com and sometimes we redirect you to https://www.acme.com. We want to redirect anyone going to http://acme.com or http://*.acme.com to http://www.acme.com, and the same for https. (It's mainly to avoid the alert you get if… >>> More

Related posts about regex

Find multiple regex in each line and skip result if one of the regex doesn't match

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a list of variables: variables = ['VariableA', 'VariableB','VariableC'] which I'm going to search for, line by line ifile = open("temp.txt",'r') d = {} match = zeros(len(variables)) for line in ifile: emptyCells=0 for i in range(len(variables)): regex = r'('+variables[i]+r')[:|=|\(](-… >>> More
OWASP Regex Repository: Is this regex correct?

as seen on Stack Overflow - Search for 'Stack Overflow'
I was looking at the regular expression for validating various data types from the (OWASP Regex Repository). One of the regular expressions in there is called safetext and looks like: ^[a-zA-Z0-9\s.\-]+$ My first question is: Is this regular expression correct? complementary question If this… >>> More
Make a Perl-style regex interpreter behave like a basic or extended regex interpreter

as seen on Stack Overflow - Search for 'Stack Overflow'
I am writing a tool to help students learn regular expressions. I will probably be writing it in Java. The idea is this: the student types in a regular expression and the tool shows which parts of a text will get matched by the regex. Simple enough. But I want to support several different regex… >>> More
JS regex isn't matching, even thought it works with a regex tester

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm writing a piece of client-side javascript code that takes a function and finds the derivative of it, however, the regex that's supposed to match with the power rule fails to work in the context of the javascript program, even though it sucessfully matches when it's used with an independent regex… >>> More
c# RegEx with "|"

as seen on Stack Overflow - Search for 'Stack Overflow'
I need to be able to check for a pattern with | in them. For example an expression like d*|*t should return true for a string like "dtest|test". I'm no regex hero so I just tried a couple of things, like: Regex Pattern = new Regex("s*\|*d"); //unable to build because of single backslash Regex Pattern… >>> More