iRev Input Validation Libraries

[Sivakatirswami]

  If any one has any input form validation-sanitizer handlers for web 
forms, (irev includes...) I could use them right now.

I've studied the web on this. It's vast... "positive match" (i.e. the 
input must be a precise match for a given set of values) is considered 
the simplest and strongest form, and I can do this for most of my 
current form input fields on this project,

But for a max 200 char comments-text field, I need something more 
robust. Our PCI auditor regularly flags some pages for XSS attacks, and 
I need to get a little more professional about sanitizing input.

I'm thinking this should suffice where the "positive match" is A-z plus 
0-9, comma, period and explanation mark... if allowed should suffice, 
but then I may need to deal with SQL injection  (PostGreSQL) also.  if 
there is no ";" then nothing can happen. But I know it is more 
complicated that that.

I know that regEx could help me here but I'm terrible with regular 
expressions.

put 
(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,x,y,z,0,1,2,3,4,5,6,7,8,9,.,!) 
into tConstraint

put toLower(tComment) into tComment

replace "," with "" in tComment

repeat for each char x in tComment
    if x is not among the items of tConstraint then
       Put "Only characters and numbers allowed in comments." into tMessage
     end
end repeat

Thanks

I'm a bit out of my depth here.  This may be an area where over 
simplication doesn't work.

Sivakatirswami