Re: [MORG] Review of draft-ietf-morg-fuzzy-search-02.txt

[Alexey Melnikov <[e-mail]>]

Barry Leiba wrote:

>>Mentioning buffer overflows sound like they could be a bit too
>>implementation specific.
>>    
>>
>I agree.  Moreover, I don't think it's the place of the IETF to tell
>programmers how to program, and buffer overflow bugs are well enough
>known that programmers should already know that they need to watch for
>them.
>
One would think so. I actually think that educating people is a good 
thing. However I am not going to insist on discussing this.

>I really don't think this opens things up for any more or
>different buffer overflow bugs than any other spec does.
>  
>
That part I agree with.

>>Implementation of this extension might enable a denial-of-service attack
>>if the implementation isn't careful to prevent them. Fuzzy search
>>engines are often complex with non-obvious disk space, memory and/or CPU
>>usage patterns. Implementors should test at least the behavior of large
>>messages that contain very long words and/or unique random strings. Also
>>very long search keys might cause excessive memory or CPU usage.
>>
>>Invalid input may also be problematic. For example if the search engine
>>takes UTF-8 stream as input, it might fail more or less badly when
>>illegal UTF-8 sequences are fed to it from a message whose character set
>>was claimed to be UTF-8. This could be avoided by validating all the
>>input and replacing illegal UTF-8 sequences with the Unicode replacement
>>character (U+FFFD).
>>
>>Search relevancy rankings might be susceptible to "poisoning" by smart
>>attackers using certain keywords or hidden markup (e.g. HTML) in their
>>messages to boost the rankings. This can't be fully prevented by
>>servers, so clients should prepare for it by at least allowing user to
>>see all the  search results, rather than hide results below a certain
>>score.
>>    
>>
>I'm happy with that text.
>
I am too. I am not convinced that mentioning Unicode replacement 
character (U+FFFD) is necessary, but I suppose it is Ok.