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Escape and URLDecode for URL passed using Ajax call

Posted on 2007-04-03
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Last Modified: 2008-02-01
I am using xmlhttp (Ajax) requests to call a PHP program from javascript using the GET method.

I am passing the PHP script a string as parameters which includes the characters %20.  For example, the current call to the PHP program looks like this:

phpparser.php?sqlstr=WHERE fieldname LIKE '%2007.03%' ORDER BY relid ASC

The %20 is cut off the param string when it reaches the PHP script, therefore messing up the MySQL query string I am passing.

I fooled around with escape and URLDecode, but how much of the URL needs to be escaped when using xmlhttp (Ajax) calls?  Should I use escape across the entire URL and then URLDecode in the receiving PHP script?

Thanks
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Question by:mamuscia
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Expert Comment

by:glcummins
ID: 18845832
A BIG word of caution on this:  You are opening up your script to a huge security attack. If you allow an SQL query to be passed as-is to your script and then executed, you have no way of knowing what is in the query. A malicious attacker can wreak havoc on your database with this kind of method.

A better option, if you can, is simple to pass the search term and order by term separately, and reconstruct the SQL statement in the script:

phpparser.php?value1=2007.03&orderby=relid&orderdirection=ASC
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Author Comment

by:mamuscia
ID: 18846022
I have many fields that the form displays to allow a user to enter to search the database.  In my PHP script I execute a SELECT so the user is constrained to reading the DB.  There is also a check to make sure the construct of the WHERE clause is correct.  How would I encode/decode this URL?
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by:Zvonko
ID: 18847181
You have to encode the query string paramter Values only.
Like this:
"phpparser.php?sqlstr="+escape("WHERE fieldname LIKE '%2007.03%' ORDER BY relid ASC")+"&some="+escape("more parametrs");

You see?
Encoding & and = of the query string is misleading like not encoding special characters in the parameter values.




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Zvonko earned 250 total points
ID: 18847189
Oh, and for decode you have not to care. That does PHP for you.

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Author Comment

by:mamuscia
ID: 18847203
this works great, thanks!!
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Expert Comment

by:Zvonko
ID: 18847252
You are welcome.
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