[Winpcap-users] RE: Opening a port multiple times and filters

[Gianluca Varenni]

Do you have a small application that replicates the problem and that you can 
send me?

Have a nice day
GV



----- Original Message ----- 
From: "Paul Rocca" <Paul.Rocca at audiosoft.co.uk>
To: <winpcap-users at winpcap.org>
Sent: Friday, January 11, 2008 3:11 AM
Subject: [Winpcap-users] RE: Opening a port multiple times and filters


> Thanks for the suggestion. I tried it, but it doesn't appear to have any
> effect, I didn't think it would as I can start and stop threads  at 
> different
> times minutes apart and still see this behaviour.
>
> Best Wishes
>
> Paul
>
> ----- Original Message ----- 
>
> Can you please try wrapping all the calls to pcap_compile() with a 
> critical section or a mutex? That API is not thread safe i.e. if you 
> happen to call that function concurrently from multiple threads, the 
> result is undefined.
>
> Have a nice day
> GV
>
>  ----- Original Message ----- 
>  From: Paul Rocca
>  To: winpcap-users at winpcap.org 
> <https://www.winpcap.org/mailman/listinfo/winpcap-users>
>  Sent: Tuesday, January 08, 2008 5:07 AM
>  Subject: [Winpcap-users] Opening a port multiple times and filters
>
>
>  I am wrining an app to capture various multicast streams to seperate 
> files.
>  In order to make my program easier to write I have 1 thread per stream, 
> and
>  open the NIC card multiple times and pull out the packets and filter them
>  in my code using src/dst ip addresses. This appears to work great, but
>  a bit CPU intensive.
>  I thought it might be easier then to use the winpcap filter function, so 
> I wrote
>  a bit of code to do this and that initially appeared to work great, BUT
>  on further investigation, it would appear that winpcap only uses the last
>  filter that was set with pcap_setfilter. i.e.
>  if I have three threads and in in each one I open an instances of my port 
> and
>  in each thread set a filter on each one (eg thread 1 = 'dst ip 
> 225.0.0.1',
>  thread 2 = 'dst ip 225.0.0.2', thread 3 = 'dst ip 225.0.0.3'), then start 
> calling
>  pcap_next_ex() in each thread, all three threads will only receive 
> packets
>  matching 'dst ip 225.0.0.3'
>
>  Is this "as designed"?, any ideas for a workaround, or is it back to 
> filtering
>  in my software?
>
>  TIA
>
>  Paul
>
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