Re: [Modcplusplus-devel] (johnksterling) mod_cplusplus/src cpp_request.cpp

[John K. S. <jo...@st...>]

Hi Jon -

FYI, I applied changes for your 3 suggestions:

1) change sprintf to snprintf (your other suggestions are good, but 
like you said probably overkill)
2) privatize the string utility methods so they're not exposed symbols
3) optimize string creation using the results of snprintf.

Thanks -

John

On Aug 4, 2004, at 5:50 AM, Jonathan Wakely wrote:

> Re-sending as I screwed it up ...
>
> On Sat, Jul 31, 2004 at 06:58:07AM -0700, Mod Cplusplus CVS List wrote:
>
>> -void ApacheRequestRec::dump()
>> +// translate integer to ascii string
>> +inline string
>> +istring(int value, const char* format = "%d")
>> +{
>> +    enum { TEMP_STORE = 50 };
>> +    char temp[TEMP_STORE];
>> +    sprintf(temp,format,value);
>> +    return string(temp);
>> +}
>
> Could a stringstream be used here instead?
> It is Mod _Cplusplus_ after all.
>
> That avoids using fixed-length buffers and format strings, two 
> potential
> security problems.
>
> The function could even be made into a template to support more than
> integers, but that might be overkill.
>
> If using sprintf(3) is needed for portability or other reasons, how 
> about
> the safer snprintf(3) ?  Or removing the format string argument ?  Does
> the (unused) flexibility of supplying a format string warrant the
> potential problems caused by passing in a format string that results in
> more than 50 chars (buffer overrun) or passing in a string that is
> incompatible with the integer argument, e.g. "%s" ?
>
> AFAICT that function isn't in an anonymous namespace, and has external
> linkage, so could potentially be called from outside that file. IMHO
> that means it should be safe against buffer overflows and format string
> injection.
>
> Maybe I'm being too paranoid - but that's the frame of mind I like to
> adopt when writing apache module code. Web servers are exposed to every
> nasty person on the net and I don't think it hurts to be paranoid.
>
> Finally, the return value of sprintf(3) could be used to speed up
> the string ctor:
>
>     const int len = sprintf(temp,format,value);
>     return string(temp, len);
>
> regards,
>
> jon
>
> -- 
> "The whole problem with the world is that fools and fanatics are always
>  so certain of themselves, but wiser people so full of doubts."
> 	- Bertrand Russell
>
>
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