June 2005 - Darwin-dev - lists.apple.com

Chaining Mach exception handlers
by Timothy J. Wood 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com -tim _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… I'm working on upgrading OmniObjectMeter to work with 10.4 better. Part of the changes deal with dyld having changed its notification method for when images are added and removed. It now calls a little stub function which gdb sets a breakpoint on as a signal to re-read the target's dyld image list. This is all fine and good except that we _also_ have our own crash catcher application, or the target application might also be running in gdb, or any number of other exception handlers could be signed up. Older versions of gdb used to have a mechanism where they'd catch the exception and forward it on to the previously registered exception handler. This is a ton of code and (a) it doesn't work if the immediately previous handler doesn't want the exception type in question (b) it doesn't seem to be in the current gdb source and (c) it doesn't seem to work for me at all. When I call exception_raise, using the previously registered exception handler port, the exception *does* get sent to the next handler, but exception_raise is not returning. I was expecting for the chained handler to get called, return its result which would get propagated back to the higher level handler via MiG, which it could then return back to its caller (all the way back to the kernel callout to the original handler). Many years ago there was some discussion about having exception handler chaining be easier. Did anything ever come of this? This email sent to site_archiver(a)lists.apple.com

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Re: [APPL:DarwinDev] Re: [RESOLVED] ICMP Router Discovery
by Jay A. Kreibich 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com User-agent: Mutt/1.4.2.1i On Wed, Jun 29, 2005 at 10:23:36PM -0700, Justin C. Walker scratched on the wall: > 'router' == 'gateway'; I'm not sure what you mean here (and I'm not > sure that it's important, either :-}) Actually, in the formal networking sense a "router" does NOT equal a "gateway". Generally, a router is a gateway but a gateway is not always a router. -j -- Jay A. Kreibich | CommTech, Emrg Net Tech Svcs jak(a)uiuc.edu | Campus IT & Edu Svcs <http://www.uiuc.edu/~jak> | University of Illinois at U/C _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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Re: [RESOLVED] ICMP Router Discovery
by Justin C. Walker 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jun 29, 2005, at 18:39 , Peter Bierman wrote: Cheers, Justin -- Justin C. Walker, Curmudgeon-At-Large Institute for General Semantics -------- Some people have a mental horizon of radius zero, and call it their point of view. -- David Hilbert -------- _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… At 5:16 PM -0700 6/29/05, Justin C. Walker wrote: On Jun 29, 2005, at 15:56 , Andre Smith wrote: The routing tables that exist on a workstation or even a server will usually only contain the route for a default router; this could also obtained using a DCHP server. If you want to discover routes advertised by routers, you probably need to implement BGP, etc. There are numerous routing protocols described in detail by RFCs, just do a google search, and you should be well on your way. Be forewarned, it will take a lot more code than a simple ping to obtain advertised routes from internet routers. Good Luck. I think, now that the dust has cleared, that Chase just wants to "know the routers that the workstation knows" (whatever that may mean). On Mac OS X, it means - querying the SystemConfiguration database - finding router addresses when those are manually configured - querying BootP/DHCP/... when they are not (depending on what's recorded for each 'location'). If that is indeed what he wants, I still don't understand why it's that complicated. Chase may want to clarify this, but I believe the issue is that a given workstation will have a specific set of routers that it "should" talk with; these are configured either manually or via DHCP/ BootP. A given subnet may have many routers, but only a few are important to the workstation, and it may not be, a priori, clear how to identify them. On Mac OS X, this is handled for all possible interfaces, in the SystemConfiguration database; for other systems, it's handled in some other way, if at all. And, at any given time, there may be only a partial set of those routers that the workstation could use identified by netstat. In the case of Mac OS X, if there are two ethernet adapters in the mix, the routers identified by netstat will be *only* those associated to the 'primary' interface of the moment. Netstat won't be aware of the router that will be identified as the default in case the current primary gets its plug pulled. Netstat can clearly identify which routes are gateways. The system has to be able to do that. 'router' == 'gateway'; I'm not sure what you mean here (and I'm not sure that it's important, either :-}) The issues you mention are all important, but they may not have an impact on what Chase is trying to do. It's been kind of hard to tell exactly what his goal is, but that's my reading. This email sent to site_archiver(a)lists.apple.com

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Re: How to determine active semaphores?
by Tron Thomas 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com User-agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) Thanks for clearing that up Paul. Paul Ripke wrote: On Monday, Jun 27, 2005, at 11:10 Australia/Sydney, Tron Thomas wrote: The sem_open, sem_close, sem_unlink family of routines implement POSIX semaphores. The semop, semget, semctl family implement System V semaphores. ipcs and ipcrm only view and delete System V objects. I don't know of any way to view what POSIX semaphores are in existence. And from memory, you're using the POSIX routines, hence nothing from ipcs. I think I led you down the wrong path with ipcs! Cheers, -- stix _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… I want to determine how many active semaphores are on my system, and I'm not sure how this can be done. It seems I can know how many semaphores are allowed by using the sysctl command. Someone had suggested that the ipcs command would be helpful. When I use it like this: ipcs -as This is the output I get, which I don't find to be helpful: Semaphores: T ID KEY MODE OWNER GROUP CREATOR CGROUP NSEMS OTIME CTIME What command can give me the information I am seeking? This email sent to site_archiver(a)lists.apple.com

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Re: [RESOLVED] ICMP Router Discovery
by Peter Bierman 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jun 29, 2005, at 15:56 , Andre Smith wrote: -pmb _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… At 5:16 PM -0700 6/29/05, Justin C. Walker wrote: The routing tables that exist on a workstation or even a server will usually only contain the route for a default router; this could also obtained using a DCHP server. If you want to discover routes advertised by routers, you probably need to implement BGP, etc. There are numerous routing protocols described in detail by RFCs, just do a google search, and you should be well on your way. Be forewarned, it will take a lot more code than a simple ping to obtain advertised routes from internet routers. Good Luck. I think, now that the dust has cleared, that Chase just wants to "know the routers that the workstation knows" (whatever that may mean). On Mac OS X, it means - querying the SystemConfiguration database - finding router addresses when those are manually configured - querying BootP/DHCP/... when they are not (depending on what's recorded for each 'location'). If that is indeed what he wants, I still don't understand why it's that complicated. Netstat can clearly identify which routes are gateways. The system has to be able to do that. There might not be a way to get netstat to give you a list of only gateways (other than using grep), but clearly the information can be had the same way netstat gets it, via the procedures explained in 'man 4 route'. All the other mechanisms, including the SystemConfig database, are just hints or possibilities. Actual packets will follow the routing table displayed by 'netstat -r'. If you want to know where actual packets will go, then get that info the same way netstat gets it. This email sent to site_archiver(a)lists.apple.com

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Re: [RESOLVED] ICMP Router Discovery
by Justin C. Walker 30 Jun '05

30 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jun 29, 2005, at 15:56 , Andre Smith wrote: I don't think he really wants to map the nearby routing infrastructure. Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large Institute for General Semantics -------- If you're not confused, You're not paying attention -------- _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… The routing tables that exist on a workstation or even a server will usually only contain the route for a default router; this could also obtained using a DCHP server. If you want to discover routes advertised by routers, you probably need to implement BGP, etc. There are numerous routing protocols described in detail by RFCs, just do a google search, and you should be well on your way. Be forewarned, it will take a lot more code than a simple ping to obtain advertised routes from internet routers. Good Luck. I think, now that the dust has cleared, that Chase just wants to "know the routers that the workstation knows" (whatever that may mean). On Mac OS X, it means - querying the SystemConfiguration database - finding router addresses when those are manually configured - querying BootP/DHCP/... when they are not (depending on what's recorded for each 'location'). This email sent to site_archiver(a)lists.apple.com

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Re: [RESOLVED] ICMP Router Discovery
by Andre Smith 29 Jun '05

29 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jun 29, 2005, at 11:44 AM, Chase wrote: On Jun 29, 2005, at 10:19 AM, Allen Smith wrote: Thanks, seriously, to everyone who helped out on this. Cheers. - Chase This email sent to andre-smith(a)speakeasy.net _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… The routing tables that exist on a workstation or even a server will usually only contain the route for a default router; this could also obtained using a DCHP server. If you want to discover routes advertised by routers, you probably need to implement BGP, etc. There are numerous routing protocols described in detail by RFCs, just do a google search, and you should be well on your way. Be forewarned, it will take a lot more code than a simple ping to obtain advertised routes from internet routers. Good Luck. 5) send DHCP requests on all ports, see if you get back any router entries for that interface. I was reading about how to do this last night. I think this and BootP are gonna help me out a lot. Without further context it's really not possible to come up with a better answer, and even with context it might just be a problem without a complete solution. These are all great answers. Everyone has really done a great job helping me out on this. I have decided, for the time being, to just get the router addresses from SystemConfiguration.framework, and it's working great, but I think everyone here has given me more than enough info to do this in a more portable way at a later time. Our first release is for Mac OS X only, so this dependency is fine. The remaining 99% of our networking codebase is POSIX- friendly, so at least this will be the only piece of code we'll have to worry about when and if we ever port to another platform. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/andre-smith% 40speakeasy.net This email sent to site_archiver(a)lists.apple.com

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Re: time outs error while connecting to opensouce cvs
by Kevin Van Vechten 29 Jun '05

29 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com $ telnet anoncvs.opensource.apple.com 22 Thanks, - Kevin On Jun 28, 2005, at 8:13 PM, She Jian, Chia wrote: Hi I am currently using the Mac OS X 10.3.9. And when I trying to log into the anoncvs.opensource.apple.com, I get this error. $ export CVS_RSH=ssh $ export CVSROOT=:ext:apsl@anoncvs.opensource.apple.com:/cvs/apsl $ cvs co mDNSResponder ssh: connect to host anoncvs.opensource.apple.com port 22: Operation timed out cvs [checkout aborted]: end of file from server (consult above messages if any) is there anything I can do to make this working? Thanks regards shejian.. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… The commands you used look correct. I tried this just now and it worked for me. Are you behind a firewall? Can you connect to the ssh server with the following? This email sent to site_archiver(a)lists.apple.com

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Re: [RESOLVED] ICMP Router Discovery
by Chase 29 Jun '05

29 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jun 29, 2005, at 10:19 AM, Allen Smith wrote: Thanks, seriously, to everyone who helped out on this. Cheers. - Chase _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… 5) send DHCP requests on all ports, see if you get back any router entries for that interface. I was reading about how to do this last night. I think this and BootP are gonna help me out a lot. Without further context it's really not possible to come up with a better answer, and even with context it might just be a problem without a complete solution. These are all great answers. Everyone has really done a great job helping me out on this. I have decided, for the time being, to just get the router addresses from SystemConfiguration.framework, and it's working great, but I think everyone here has given me more than enough info to do this in a more portable way at a later time. Our first release is for Mac OS X only, so this dependency is fine. The remaining 99% of our networking codebase is POSIX-friendly, so at least this will be the only piece of code we'll have to worry about when and if we ever port to another platform. This email sent to site_archiver(a)lists.apple.com

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Re: ICMP Router Discovery
by Allen Smith 29 Jun '05

29 Jun '05

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com User-agent: KMail/1.7.1 There might not be a router. There are stub networks out there that have no routers. There could be multiple routers on each of the networks those interfaces are connected to. If they aren't configured on the host, it won't know about them and depending on the configurations of the routers, they may not advertise their presence. There are ways to try and find a router that is not configured on the host. None are sure-fire, few are easy, and some will only a small chance of finding something. A few could cause badness in local network if the routers are too trusting. 1) Join one of the mcast groups related to routers and listen for traffic: 224.0.0.2 All routers on this subnet 224.0.0.5 OSPF routers 224.0.0.6 OSPF designated routers 2) Listen for OSFP/ISIS/RIP/EIGRP hello type packets. Senders are likely routers. 3) icmp router discover (RFC1256). 4) scan local network for hosts and use SNMP (hope for public read-only) to see if the device is a router. 5) send DHCP requests on all ports, see if you get back any router entries for that interface. 6) Fire up RIP/OSPF/ISIS and see if you can talk to anyone. 7) scan local network and then try sending icmp requests to a remote ip through each of the hosts, if you get a positive response then you've found a router, if you get an icmp-redirect then you've found two! Without further context it's really not possible to come up with a better answer, and even with context it might just be a problem without a complete solution. -Allen On Tuesday 28 June 2005 06:00 pm, Chase wrote: > On Jun 28, 2005, at 7:13 PM, Justin C. Walker wrote: > > > Can you describe your goals? > > > the goal is simply to get a router address for a given interface. > > i have a list of interfaces. some have ip addresses. some don't. > for those that do, i need the gateway address that they are connected > to. > > that's all. > > - chase > > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/darwin-dev/lazlor%40bigboy.lotaris.o… > > This email sent to lazlor(a)bigboy.lotaris.org > _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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