[Winpcap-users] pcap_findalldevs Hangs when calledinWindowsservice

Mon Aug 14 17:03:41 GMT 2006

----- Original Message ----- 
From: "Thomas O'Hare" <Tom at redtile.com>
To: <winpcap-users at winpcap.org>
Sent: Monday, August 14, 2006 9:20 AM
Subject: Re: [Winpcap-users] pcap_findalldevs Hangs when 
calledinWindowsservice

> Richard
>
> If that is the case then my 2 cents says it's a security issue.  XP has,
> IMO, much worse security setup then server OS's.

A security issue shouldn't cause an app to hang. My suspect is that there's 
a problem with service dependencies causing a deadlock: the service control 
manager (SCM) holds some locks while starting a service, similar to the 
loading of a Dll, so special care should be taken in calling some SCM 
routines (similar to the limitations when writing the DllMain entry point of 
a Dll).

Have a nice day
GV

>
> But that all makes sense, XP & security.
>
> Thanks,
> ~ Thomas O'Hare ~
> President, RedTile, Inc. - DBA: RedTile Software
> Web, Wireless, Network, Database & Systems Software
> +1.407.295.9148 ; +49.8651.717950 ; http://www.RedTile.Com/
> Operations Manager; Virtual FoxPro User Group
> Tom at VFUG.Org ; http://www.VFUG.Org/
>
>
> Richard Bellengere wrote:
>> Hi.
>>
>> It seems to be either an XP thing or particular to my machine. I got it
>> running on a Server2000 machine - First Time!
>> I will try some other machines here in the office if I can get my hands
>> on them.
>>
>> Regards
>> RichardB
>>
>> ________________________________
>>
>> From: winpcap-users-bounces at winpcap.org
>> [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
>> Sent: 11 August 2006 18:00
>> To: winpcap-users at winpcap.org
>> Subject: Re: [Winpcap-users] pcap_findalldevs Hangs when
>> calledinWindowsservice
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: Richard Bellengere <mailto:RichardB at thoroughtec.com>
>> To: winpcap-users at winpcap.org
>> Sent: Friday, August 11, 2006 5:36 AM
>> Subject: RE: [Winpcap-users] pcap_findalldevs Hangs when
>> calledinWindowsservice
>>
>> Hi.
>>
>> Checked Visual Studio 2005 Express and WinPCap version 4.0.
>> Checked Visual Studio 2003 C++  and WinPCap version 4.0.
>> Checked program compiled as Multibyte Characters and Unicode
>> Characters.
>>
>>
>> This doesn't influence WinPcap.
>>
>>
>> Checked program compiled linked to runtime libraries in
>> multithreaded dll and static inclusion of multithreaded runtime
>> libraries.
>> I tried compiling the same code in to a windowed app (instead of
>> console app) and running that as a service.
>>
>> All result in the same problem. pcap_findalldevs hangs.
>>
>> The documetation makes reference to pcap_findalldevs_ex, but I
>> have not been able to find it in headers and compile, Am I missing
>> something?
>>
>>
>> If you want to use pcap_findalldevs_ex, just include pcap.h (do *NOT*
>> include any other header), and have both WPCAP and HAVE_REMOTE defined
>> as preprocessor directives. In any case pcap_findalldevs_ex is a wrapper
>> against pcap_findalldevs, which in turn calls PacketGetAdapterNames,
>> which is almost certainly the API that hangs. So it does not help.
>>
>>
>> Is it time to start loading the debug version of the packet.dll
>> to get more information?
>>
>>
>> That would be very helpful. Please use WinPcap 4.0alpha1, as this
>> version produces a much more verbose trace.
>>
>> Have a nice day
>> GV
>>
>>
>> Regards
>> RichardB
>>
>> ________________________________
>>
>> From: winpcap-users-bounces at winpcap.org
>> [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
>> Sent: 10 August 2006 18:15
>> To: winpcap-users at winpcap.org
>> Subject: Re: [Winpcap-users] pcap_findalldevs Hangs when
>> calledinWindowsservice
>>
>>
>> Richard,
>>
>> I'll try to create a small test application to reproduce the
>> problem. One thing came to my mind: have you changed the compilation
>> properties of your application so have it thread safe?
>>
>> Under VC2003, it's in the project properties, under C/C++ ->
>> Code generation -> Runtime Library. Be sure to set it to set it to
>> multithreaded (or multithreaded DLL, depending on the flavor of CRT that
>> you want to use).
>>
>> have a nice day
>> GV
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: Richard Bellengere
>> <mailto:RichardB at thoroughtec.com>
>> To: winpcap-users at winpcap.org
>> Sent: Thursday, August 10, 2006 1:06 AM
>> Subject: RE: [Winpcap-users] pcap_findalldevs Hangs when
>> called inWindowsservice
>>
>> Hi
>>
>> Sorry - my sample app depends on way too much for me to
>> quickly zip it up and post it.
>>
>> I'm using 3.1. I will try 4.0 and let you know what
>> happens.
>> I'm using Visual C++ 2005 Express. I will try Visual
>> Studio 2003 for size too.
>>
>> Some more information that may be of interest.
>> My service is compiled as a console application. When
>> running it (in debug mode) as a console app and not a service,
>> pcap_findalldevs is successful only if run from the main thread.
>> pcap_loop can be run from the new thread no problem.  When I do the same
>> thing in a windowed application I can call pcap_findalldevs from the new
>> thread without issue.
>>
>> It really smacks of a thread permissions issue. I've
>> tried making sure the apps and services are running as admin (because of
>> npf and nm), but that does not seem to help. Right now I'm trying to
>> find out what the difference is between a console thread and a Window
>> thread.
>>
>> Regards
>> RichardB
>>
>> ________________________________
>>
>> From: winpcap-users-bounces at winpcap.org
>> [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
>> Sent: 09 August 2006 19:15
>> To: winpcap-users at winpcap.org
>> Subject: Re: [Winpcap-users] pcap_findalldevs Hangs when
>> called in Windowsservice
>>
>>
>> Richard,
>>
>> can you please provide a sample app showing the problem?
>>
>> Which version of WinPcap are you using? WinPcap 3.1 has
>> a known bug that affects services based on WinPcap, bug that has been
>> fixed in the newer versions of WinPcap like 4.0alpha1.
>>
>> Have a nice day
>> GV
>>
>> ----- Original Message ----- 
>> From: Richard Bellengere
>> <mailto:RichardB at thoroughtec.com>
>> To: winpcap-users at winpcap.org
>> Sent: Tuesday, August 08, 2006 5:44 AM
>> Subject: [Winpcap-users] pcap_findalldevs Hangs
>> when called in Windows service
>>
>> Hi.
>>
>> I'm getting exactly the same thing.  Did you
>> ever get a solution to this problem?
>>
>> It seems to have something to do with
>> findalldevs being called from a new thread and not the process's main
>> thread.
>>
>> Thanks
>> RichardB
>>
>>
>> ________________________________
>>
>>
>>
>>
>> _______________________________________________
>> Winpcap-users mailing list
>> Winpcap-users at winpcap.org
>>
>> https://www.winpcap.org/mailman/listinfo/winpcap-users
>>
>>
>>
>> ________________________________
>>
>>
>>
>>
>> _______________________________________________
>> Winpcap-users mailing list
>> Winpcap-users at winpcap.org
>> https://www.winpcap.org/mailman/listinfo/winpcap-users
>>
>>
>>
>> ________________________________
>>
>>
>>
>>
>> _______________________________________________
>> Winpcap-users mailing list
>> Winpcap-users at winpcap.org
>> https://www.winpcap.org/mailman/listinfo/winpcap-users
>>
>>
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> Winpcap-users mailing list
>> Winpcap-users at winpcap.org
>> https://www.winpcap.org/mailman/listinfo/winpcap-users
> _______________________________________________
> Winpcap-users mailing list
> Winpcap-users at winpcap.org
> https://www.winpcap.org/mailman/listinfo/winpcap-users 