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RegEx to validate textarea and prevent spambots

Posted on 2008-06-26
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Last Modified: 2011-09-20
I am getting spambots on my form and have done some form filtering but a big thing I am getting are URLs in my textarea form field. How would I code my form processing page using regular expressions to validate there are no URLs (i.e. - http://) in my textarea?

Example of what I need in bad code form:

commentsBox=request.form("comments")

regex = "{http://}"

if commentsBox contains regex then
WriteToFile "webcsv\myform_spam.csv", contents, True
else
WriteToFile "webcsv\myform.csv", contents, True
end if

Thanks!

~Aus2Srq
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Comment
Question by:Aus2Srq
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8 Comments
 
LVL 16

Expert Comment

by:ThinkPaper
ID: 21877070
you're just checking http:// URLs, nothing else?

you've got several variations to consider.. below's a good chunk of regex's to consider..

http://www.truerwords.net/articles/ut/urlactivation.html
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LVL 16

Expert Comment

by:ThinkPaper
ID: 21877360
also.. what type of form is this? is it like a registration form?

considering using tools like CAPTCHA images to eliminate spam registration..
0
 
LVL 27

Expert Comment

by:ddrudik
ID: 21877878

<%
Set regEx = New RegExp
regEx.Global = False
sourcestring = "your source string"
regEx.Pattern = ".*https?//"
Set Matches = regEx.Execute(sourcestring)
If Matches.Count > 0 then
 ' do something
Else
 ' do something else
End If
%>

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LVL 27

Expert Comment

by:ddrudik
ID: 21877888
One more change:
<%
Set regEx = New RegExp
regEx.Global = False
regEx.IgnoreCase = True
sourcestring = "your source string"
regEx.Pattern = ".*https?//"
Set Matches = regEx.Execute(sourcestring)
If Matches.Count > 0 then
 ' do something
Else
 ' do something else
End If
%>

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Author Comment

by:Aus2Srq
ID: 21878792
Using your code as a base, I did a Google search and modified the code a bit as I don't care if I know the number of patterns found, I just need to know true or false I did the following.

However, it's failing to find the pattern and still submitting the form as normal. Do I need to change my variable to a string to search?

Thanks!

~A2S
commentsBox = request.form("comments")
 
Set regEx = New RegExp
With regEx
.Pattern = ".*https?//"
.IgnoreCase = True
.Global = False
End With
foundPattern = regEx.Test(commentsBox)
 
If foundPattern Then
  WriteToFile "webcsv\myform_spam.csv", contents, True
else
  WriteToFile "webcsv\myform.csv", contents, True
End If
Set regEx = nothing

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LVL 27

Accepted Solution

by:
ddrudik earned 2000 total points
ID: 21878991
I forgot the colon in the pattern, either revision would work with the new pattern below.  Note that you cannot test as you did, once the FoundPattern is created as a regEx.Test object it exists.  The best you can do is test if Matches.Count exists which reports false if it is equal to 0.
<%
Set regEx = New RegExp
regEx.Global = False
regEx.IgnoreCase = True
sourcestring = "http://www.yahoo.com/"
regEx.Pattern = ".*https?://"
Set Matches = regEx.Execute(sourcestring)
If Matches.Count then
  Response.Write "SPAM"
Else
  Response.Write "NOT SPAM"
End If
%>

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Author Closing Comment

by:Aus2Srq
ID: 31471076
Thank you very much ddrudik! It works perfectly.

On a side note, could you leave a last comment on how I would add an or in the regex? Such as looking for "http://" or "www.*.com" for instance.

Thanks again!

~Aus2Srq
0
 
LVL 27

Expert Comment

by:ddrudik
ID: 21879826
Thanks for the question and the points.
<%
Set regEx = New RegExp
regEx.Global = False
regEx.IgnoreCase = True
sourcestring = "test www.yahoo.com test"
regEx.Pattern = "(?:.*https?://)|(?:.*www\..*\.com)"
Set Matches = regEx.Execute(sourcestring)
If Matches.Count then
  Response.Write "SPAM"
Else
  Response.Write "NOT SPAM"
End If
%>

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