site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Dec 20, 2006, at 6:17 PM, Bhavesh Davda wrote: When calling mbuf_outbound_finalize() to compute the incomplete TCP/UDP checksums on the mbuf from my iff_output_func (interface filter output function), I kept getting messages from the kernel "cksum: out of data". Looking at the xnu-792.13.8 source, it looks like the underlying in_cksum_skip, called from in_delayed_cksum_offset, expects the ip_len field in the IP header to be in host-byte-order, while in reality the mbuf handed to my iff_output_func had the ip_len field in the IP header correctly populated in network-byte-order. This is a known bug and a fix is already in order. Assuming that you call this from an interface filter, and that only the transport checksum is to be recomputed, you should be able to byte-swap the IP length, call mbuf_outbound_finalize() and restore the IP length back to the network-byte order. If the driver offloads IP header checksumming, and if this is an IPv4 packet, then you would need to recompute the IP header checksum yourself prior to sending the packet downstream. Once the fix is made available, you will no longer need to do any of the above. (Also note that this issue does not exist for PPC.) Adi Thanks! -- Bhavesh P. Davda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/adi%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com What is my iff_output_func to do in such a situation? This email sent to adi@apple.com smime.p7s