(usagi-users 04083) Re: mip6d portability issues

[Romain KUNTZ <kuntz@xxxxxxxxxxxxxxxxxx>]

Hi Jozsef,

On 2008/11/07, at 2:20, Jozsef Kovacs wrote:
> nd_opt_hdr is not a packed struct (defined in netinet/icmp6.h) and  
> it's not guaranteed that the length of the struct (two uint8_t  
> fields) will be 2 bytes on every architecture, thereby dropping a  
> completely valid RA packet. In my case on an arm device the size of  
> the struct was 4bytes.

We think this is a header file bug: structures should be packed in  
order to avoid such issues. We will investigate that on our side in  
order to check if a change in the header file is possible. That would  
avoid to implement workarounds in the userland code.

> By fixing this the daemon worked correctly, but there still might be  
> some hidden bugs caused by sizeof(struct) checks.

Do you mean that you have just added a "packed" attribute to the  
structure in the header file? Or modified the userland code? Please  
send us a patch of your fix if you don't mind.

Regards,
--
Romain KUNTZ
kuntz@xxxxxxxxxxxxxxxxxx
LSIIT - Networks and Protocols Team
http://clarinet.u-strasbg.fr/~kuntz/