On Sun, Dec 08, 2002 at 04:16:24AM -0800, RuiJH wrote: > hi, > I did one test in my localhost with ping -R. And you > are right. > But maybe some points are ignored. > when a packet arrives,it will enter iplayer next > ip_options be processed and srr pointer will be backward > "4 bytes". After all these have be done, packet will be > submited to upper layer,like tcp,udp.Any socket created by > SOCK_RAW will get "updated" packet.So if now you want to > recheck the whole packet,the checksum should undoubtfully > be wrong and not be equal to the old one. At a first glance, this behavior seems wrong to me. It would undoubtfully be more consistent if the kernel either left the packet alone or, if it really wants to update the RR option, it did the job right and recomputed the checksum, too. Of course, there might be some deeper reasons for this behavior that I cannot see. > In a word , ip srr options has been processed before > you capture packet.I suggest you can try "SOCK_PACKET". > Maybe it will can work suitable. Well, I would rather avoid SOCK_PACKET as it is marked "Obsolete and should not be used in new programs" in the docs. pvl - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
