February 2006 - Darwin-kernel

Re: kpi_ipfilter modifying checksum
by Terry Lambert 15 Feb '06

15 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Feb 14, 2006, at 3:20 PM, matt jaffa wrote: Hi, <http://fxr.watson.org/fxr/source/altq/altq_blue.c?v=NETBSD> -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… I am changing the inbound data on a kpi_ipfilter. I need to redo the checksum so the packet is not thrown away. I have been told there is a method in the kernel that can calculate the checksum by passing in the mbuf reference or it was an unsigned char array. Does anyone know where this might be? This was on 10.3, so is there one available on Tiger I could use? RFC1624 describes a method to incrementally update a packet checksum, when modifying the packet contents. Using this method, you avoid the problem of computing a good checksum for a corrupt packet and letting it past, because you update the checksum in place; if the packet didn't have a good checksum before, it won't have one after. You also avoid the overhead of recomputing the checksum over the entire packet contents, which can be a real performance problem. There's sample code that does this in ALTQ; here's one reference (search in the page for RFC1624): I've personally used RFC1624 in the implementation of an L4 load balancer, and for implementing TCP splicing, and the performance savings for this approach can be considerable. This email sent to site_archiver(a)lists.apple.com

1 0

programming assist
by Robert Jagitsch 15 Feb '06

15 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=R5G/96P3kw5hrCWWIj4DhbK82joRT2ADVTo0tm174OM+k/olWebA7arVZLosxMVfcUg/5muXpW3eDh0nXPRlfP9KBV3pTGf0XAFkO8Pp7RywgqhfMKht2Yngtz3FO7QgL7s+gWJSqHiEMLs8xpQzfj1M3kq0sjHY13UDzazF/zw= Hi, we are looking for someone to assist with some kernel extension work, specifically for Darwin 8.5. I hope this is ok by the rules...please email c2s_98 at yahoo.com...TIA _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: kpi_ipfilter modifying checksum
by Andrew Gallatin 15 Feb '06

15 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com matt jaffa writes: > Hi, > > I am changing the inbound data on a kpi_ipfilter. I need to redo the > checksum so the packet is not thrown away. > I have been told there is a method in the kernel that can calculate the > checksum by passing in the mbuf reference or it was an unsigned char array. > Does anyone know where this might be? This was on 10.3, so is there one > available on Tiger I could use? You're probably thinking of in_cksum or in_cksum_skip. You can pick up BSD licensed versions of these routines from nearly any BSD OS. (Free,Net,Open,Dragonfly). Drew _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: kpi_ipfilter modifying checksum
by Josh Graessley 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com -josh On Feb 14, 2006, at 3:20 PM, matt jaffa wrote: Hi, Thanks, Matt _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/jgraessley%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com This didn't make it in to Tiger. You'll need to manually calculate the new checksum. It is also very important to verify the old checksum before modifying the packet. If there was corruption and you simply modify the packet then calculate the right checksum, you've effectively disabled the checksum. I am changing the inbound data on a kpi_ipfilter. I need to redo the checksum so the packet is not thrown away. I have been told there is a method in the kernel that can calculate the checksum by passing in the mbuf reference or it was an unsigned char array. Does anyone know where this might be? This was on 10.3, so is there one available on Tiger I could use? This email sent to jgraessley(a)apple.com smime.p7s

1 0

kpi_ipfilter modifying checksum
by matt jaffa 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type; b=XNcpC94Oh1jRCJzSLBd7bbHi0/4yftjDq5ALCzUT/lm2hdvj8fGjRl0iagE86AM1/Z+yD1OX6WCCqYb9HxKsdVvN4pP4lr3RDJ84ZTqJIzexUHYQiFsZzf4/4OLOPggmUcmlSxlJyQJV125Sl0iwdAim2ajDcm2inWcIJffn71U= _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: Anyway to call syscall in kernel extension?
by Josh Graessley 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com smime.p7s

1 0

Re: Getting hostname info from within kernel code
by Mike Smith 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Feb 14, 2006, at 4:40 AM, Alexander Kluyev wrote: Is there way to get hostname (MachineName, ComputerName) from within my KEXT I'm writing? It seems I saw "some useful global variables like hostname, hostnamelen" description somewhere in documentation. However I cannot find it once again. Does anyone have experience regarding that? Thank you. = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Host names are associated with interface addresses, and can change at any moment. Since there's no good way to post notifications for these sorts of events in the kernel, it's generally not a good idea to try to use them there. There's also not much use for hostnames in the kernel, since they have to be converted to protocol addresses before use anyway. The same can be said of the "computer name", although it tends to change even more randomly. You're better off managing name/address translations outside the kernel, since they tend to be asynchronous operations that require the support of large amounts of library infrastructure. This email sent to site_archiver(a)lists.apple.com

1 0

Re: Getting hostname info from within kernel code
by Andrew Gallatin 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Alexander Kluyev writes: > Hi guys, > > Is there way to get hostname (MachineName, ComputerName) > from within my KEXT I'm writing? It seems I saw "some useful > global variables like hostname, hostnamelen" description > somewhere in documentation. However I cannot find it once again. > Does anyone have experience regarding that? Thank you. You're not allowed to access these variables directly, as they are not exported. The last I checked, you cannot use sysctl to access them from inside the kernel, and sysctlbyname does not work for kern.hostname. I had to get around this by launching a usermode helper which then told my kext what the hostname was. Talk about Rube Goldburg... Drew _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Getting hostname info from within kernel code
by Alexander Kluyev 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Organization: MusicLab, Inc. Hi guys, Is there way to get hostname (MachineName, ComputerName) from within my KEXT I'm writing? It seems I saw "some useful global variables like hostname, hostnamelen" description somewhere in documentation. However I cannot find it once again. Does anyone have experience regarding that? Thank you. Alexander, klax(a)musiclab.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: Anyway to call syscall in kernel extension?
by Lex Dejavu 14 Feb '06

14 Feb '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=GpXQh5oLhRNCdvpLHooqQGwdytGUpdu5/0M7SRYhr7UaTU3klyRsd7VR1Wm4lZpApnmHiUMDLFapmMjlwfnIduCE4BDu4JDbmgs9LhCt55Qr8Zn/omOMMC5qeQusFtwyTLKr8EZBi8gZOevThBNMf0UZWuLQuYzUwS1pus/EjCA= ; _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0