From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25777 invoked by alias); 17 Jun 2005 12:57:47 -0000 Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Received: (qmail 25744 invoked by uid 22791); 17 Jun 2005 12:57:38 -0000 Received: from sta-206-168-96-204.rockynet.com (HELO hermes.chez-thomas.org) (206.168.96.204) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Fri, 17 Jun 2005 12:57:38 +0000 Received: by hermes.chez-thomas.org (Postfix, from userid 2000) id 9275E100410; Fri, 17 Jun 2005 06:57:29 -0600 (MDT) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by hermes.chez-thomas.org (Postfix) with ESMTP id BAD9C10040F; Fri, 17 Jun 2005 06:57:27 -0600 (MDT) From: Gary Thomas To: Nick Garnett Cc: Andrew Lunn , Sturle Mastberg , eCos Discussion In-Reply-To: References: <42B28F30.1070905@tandberg.net> <1119002495.13965.224.camel@hermes> <42B2ACAD.5030608@tandberg.net> <20050617112810.GA4982@lunn.ch> Content-Type: text/plain Date: Fri, 17 Jun 2005 12:57:00 -0000 Message-Id: <1119013047.13965.253.camel@hermes> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [ECOS] Possible fix for duplicated ARP entries in the FreeBSD stack X-SW-Source: 2005-06/txt/msg00140.txt.bz2 On Fri, 2005-06-17 at 13:53 +0100, Nick Garnett wrote: > Andrew Lunn writes: > > > On Fri, Jun 17, 2005 at 12:57:49PM +0200, Sturle Mastberg wrote: > > > Gary Thomas wrote: > > > >On Fri, 2005-06-17 at 10:52 +0200, Sturle Mastberg wrote: > > > > > > > >>Hello, > > > >> > > > >>For some time I've had problem with duplicated ARP entries that have > > > >>caused all sorts of problems. I searched the archive and discovered that > > > >>the problem had been reported before: > > > >> > > > >> > > > >>http://sourceware.org/ml/ecos-discuss/2004-11/msg00097.html > > > >> > > > >> > > > >>My proposal to a fix is to make the sockaddr_inarp struct > > > >>(include/netinet/if_ether.h) equal in size to the sockaddr struct by > > > >>padding it at the end. This is exactly what is done to the sockaddr_in > > > >>struct (include/netinet/in.h) for different reasons. > > > >> > > > >> > > > >>I reached this conclusion after I discovered that two virutally > > > >>identical calls to rtalloc1 (net/route.c) returned different results. > > > >>The first instance appears in arplookup (netinet/if_ether.c) where the > > > >>first parameter to rtalloc1 is a struct sockaddr_inarp cast to a struct > > > >>sockaddr. The second instance appears in ip_output (netinet/ip_output) > > > >>via rtalloc_ign (net/route.c) where the first parameter to rtalloc1 is > > > >>an actual struct sockaddr. The rtalloc1 function does a radix tree > > > >>search with a call to the rn_match function (net/radix.c). A closer look > > > >>at this code reveals that it does indeed depend on the size of the > > > >>supplied struct. > > > >> > > > >> > > > >>The only conclusion a can draw from this is that the three structs: > > > >>sockaddr, sockaddr_in and sockaddr_inarp must all be of equal size. I > > > >>have checked the FreeBSD source repository that this is the case for the > > > >>original code. > > > >> > > > >> > > > >>While browsing the FreeBSD source repository I discovered that the > > > >>sa_data character array member of the sockaddr struct was increased in > > > >>size in the eCos FreeBSD stack. Does anyone know why this increase was > > > >>introduced in eCos? > > > > I beleave Nick did this for IPv6. This bigger size allows an IPv6 > > address to be placed into a sockaddr which you cannot normally do. > > I thought that initially and had a look. The change I made was to > struct sockaddr_in to make it match the increased sockaddr size so > that some punned data structures would match. I think the change to > struct sockaddr was done by Gary during the initial port to make IPv6 > addresses fit correctly. I'm sure it all has something to do with the > lack of user/kernel space and the fact that we don't copy things to > and fro as much as the BSD kernel does. This is as I remember it as well. Note the comment in the structure (which I did not add or change) that bodes of this inconsistency. Of course, if someone has a better way to handle it, feel free to post a patch :-) -- ------------------------------------------------------------ Gary Thomas | Consulting for the MLB Associates | Embedded world ------------------------------------------------------------ -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss