Re: Suggestion on how to eliminate Cross-site-scripting (XSS) bugs for good.

>> Having read the thread, I don't think that's enough for me. I want to still
>> need to explicitly specify "ESCAPE=HTML" everywhere (without having a default
>> escape), to have an exception raised on a non-escaped occurence, and to add
>> an explicit unescaping (like "ESCAPE="0"").
> 
> Let me see if I've got this straight: you want to force the template
> writer to include "ESCAPE=something" in every TMPL_VAR, where
> "something" can be "HTML", "URL", or a value indicating "no escapes"
> (say, "TEXT"); failure to do so would cause a catchable error in your
> script when you try to evaluate the template.  Right?

hmm... it doesn't sound right at all.  Forcing the developer to
remember to have to type ESCAPE=... for every TMPL_VAR is just not
right.

I personally forget to even use NAME=...  and I just about never
quote the value either due to laziness.

The reality is that people are lazy/forgetful/efficient - the
general idea in life is to make life easier, not harder.  I'd
suggest just to use the functionality as is.  ie: set default_escape
to whatever the default is; when no escape is necessary, then the
developer will explicitly say so.

>> So I guess I'm going to fire up my editor and write an HTML::Template
>> sub-class.
> 
> Probably.  May I suggest a form for your subclass to take?  Let
> "default_escape" contain two additional values: "TEXT" (which means
> the same as "0" above, and can also be used in 'ESCAPE=' to override
> the default with no escaping), and "NONE" (which throws an exception
> any time a TMPL_VAR lacks 'ESCAPE=').  This will let you easily switch
> to an appropriate default_escape value once transition to the new code
> is complete.

Please dont use "TEXT" to mean none - there is at least one filter
that has been posted on this list which is for 'text' documents.
ie: the filter is like the HTML filter, but also handles newlines &
carriage returns, etc.  How about "NONE" or "NO" or "0" to mean 'no
escaping is necessary'.

Also, "NONE" (as described above) should be "THROW" - the term is
common in computer science, lets use it.

Mathew

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