Wireshark · Wireshark-dev: Re: [Wireshark-dev] Netflow dissector bug-to-be

[Hadriel Kaplan <HKaplan@xxxxxxxxxxxxxx>]

On Nov 7, 2010, at 12:33 PM, Jakub Zawadzki wrote:

> On Sun, Nov 07, 2010 at 10:46:47AM -0500, Hadriel Kaplan wrote:
>> Howdy,
>> The current packet-netflow.c dissector has a big "switch (pen_type) {...}" block in dissect_v9_v10_pdu_data(), which looks up specific known netflow/ipfix fields as it walks netflow v9/10 PDUs.
>> 
>> Unfortunately, it's a bit of a hack as pen_type is a guint64 and a switch statement will silently cast it to an int.
> 
>> I say "unfortunately", because I discovered to my chagrin that it's a *signed* int, so any case statement can't use a constant greater than 0x7fffffff, 
>> which given how the current code works, means one can't have a Private Enterprise Number greater than 0x7fff and use it to define a known field in this code.
>> As it turns out, my Enterprise number is higher than that. (Cace Technology's is just under it, which is why the current code works for Cace's netflow fields)
> 
> Have you tried adding 'U' to your #define? i.e.
> 
> instead of just:
>   #define VENDOR_FOO 0xdead
> 
> do:
>   #define VENDOR_FOO 0xdeadU
> 
> or even better:
>    #define VENDOR_FOO G_GUINT64_CONSTANT(0xdead) /* which should result in 0xdeadLLU */

It won't help - if you force it to be bigger than an int, gcc errors that the switch's case statement is not an integer... and apparently ISO C agrees with it: switch/case is defined to use an int size (and since int is 16 bits on some systems, makes me wonder if this isn't already failing for Cace's enterprise number on such systems).

-hadriel