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Re: (tye)Re2: A proposal for improvements to Net::Ping

by Falkkin (Chaplain)
on Mar 10, 2001 at 23:52 UTC ( #63511=note: print w/replies, xml ) Need Help??

in reply to (tye)Re2: A proposal for improvements to Net::Ping
in thread A proposal for improvements to Net::Ping

Your point (2) I agree with... I propose the creation of a new module, Net::Ping::External, to handle the use of the system's ping command. Net::Ping will know how to use the module, through a new protocol called "external", and the "auto" protocol of Net::Ping will skip the "external" protocol if Net::Ping::External is not installed on the system or if Net::Ping::External can't find a suitable ping command. If we could get documentation on what various systems' ping commands return on success/failure, that would be the easiest way to parse the results... otherwise, we'll probably need to use regexes and the like to parse results on a system-by-system basis.

(3) Yes, you are correct in your interpretation of what I want to do with the "auto" protocol.

(4) I just found out the hard way that non-blocking connect doesn't work under Win systems. Why is that? Setting SO_RCVTIMEO and/or SO_SNDTIMEO doesn't work, under any OS, AFAIK because no data is actually being sent or received. If the Socket modules use alarm() to implement timeouts, do these timeouts work on non-alarm()-supporting systems (i.e. Windows)? Does anybody have any further ideas on how I can get a TCP ping to timeout on WinXX systems? My only thought at this time is to use Win32::CreateProcess or fork() to spawn a child, and kill it if it's not returned by the time the timeout has passed.

(5) select() does make perfect sense in this situation. I still think that this is functionality I would rather pull into another new module, Net::Ping::Parallel, instead of adding feature-bloat to the current module.

This has generated a lot of discussion; I'm wondering if I shouldn't create a Sourceforge account for this project such that there is a central place to store the various advantages/drawbacks to each of the proposed enhancements, and a CVS account so that people can view the current progress (and any interested perlers can contribute code.) Once the code has been mostly "fixed", I'll post it to the code section here for further review. I think the sourceforge page should probably be posted to comp.lang.perl.modules or comp.lang.perl.misc (I frequent neither newsgroup so I don't know offhand which would be most appropriate).

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(tye)Re3: A proposal for improvements to Net::Ping
by tye (Sage) on Mar 11, 2001 at 00:24 UTC

    2) BTW, I'd just bundle Net::Ping::External in with Net::Ping so they are installed together (though making Net::Ping robust in the face of no Net::Ping::External is still a good idea).

    4) As I mention in Net::Ping, the mini series, non-blocking connect not working is simply a bug in WinSock (both 1 and 2). You can use the non-standard Async* APIs to do non-blocking "connect" under Win32, but using Win32::CreateProcess is going to be a lot less work so that is the way I would go for Win32. Switching from alarm to non-blocking connect makes sense for Unixy systems. And no, the Perl Socket modules don't support connect timeouts under Win32 (they detect that alarm is not supported and silently disable the timeout for connect).

    5) Yes, I like the idea of Net::Ping::Parallel but suspect that the code and API will be so similar between Net::Ping and Net::Ping::Parallel, that it makes sense to have them rather tightly interconnected. For example, it might work to teach Net::Ping to support an asynchronous API that Net::Ping::Parallel uses. In the end, whether these are independant modules, interconnected modules, two module that use a third, lower-level module, or even just two name spaces handled by a single module depends on the grimy details when you get to implementing them.

            - tye (but my friends call me "Tye")

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