[nycphp-talk] User Input Data scrubbing

Michele Waldman mmwaldman at
Fri Nov 28 15:04:26 EST 2008

Could ya'll repost any responses to this.  Apparently, my new email address
wasn't subscribed to the mailing list.



From: Michele Waldman [mailto:mmwaldman at] 
Sent: Friday, November 28, 2008 2:06 PM
To: 'NYPHP Talk'
Subject: User Input Data scrubbing


I'm trying to scrub data input to insert into a database which I will later
display on the website.


In order to prevent sql injections and html injections into the code, I
figured I'd just replace non alphanumeric characters with their html special
character codes and remove any control characters all together except
carriage return.


The ascii character codes only go up to 255.


However, there are lots more characters in html.


If the user creates a string from which was generated using html using
characters outside of the ascii character codes, what do those get
translated to in the string?  A garage character?


Is that a concern?  Or is my only concern those 255 characters in the ascii
chart?  I'm thinking the 255 characters covers it all.  The characters are a
finite set which were long ago predefined, unless that changes in the
future, right?  This means scrubbing the data is a short function.


I'm not using mysql_real_escape_string, because I replace all ' and " with
their html character code.


I'm not using htmlspecialchars, because it wasn't thorough enough.  I simply
wrote a function that replaces just about every character with it's html
character code.


I'm doing this in php after the data is passed to me.


Now, in the case of ajax, I just need to come up with a good approach for
checking the data received from php, which may vary depending on the type of
ajax used.



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