[Winpcap-users] pcap_findalldevs Hangs when calledinWindowsservice

[Richard Bellengere]

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

			
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