[Winpcap-users] Better Performance

[Charu Agrawal]

Hi,

 

This is what the code looks like - 

 

This is all initialization code - 

 

                if ((adhandle= pcap_open_live(d->name,            //
name of the device

 
65536,                                  // portion of the packet to
capture. 

 
// 65536 grants that the whole packet will be captured on all the MACs.

 
1,                                                           //
promiscuous mode (nonzero means promiscuous)

 
1,                                           // read timeout

 
errbuf                                  // error buffer

 
)) == NULL)

                {

                                printf("\nUnable to open the adapter. %s
is not supported by WinPcap\n", d->name);

                

                                return RETCODE_ERR;

                }

 

                //Set the filter string to the source ip address

                //Only packets from this source address will be
captured.

                //This does slow down the capture a bit.

 

  NetMask=0xffffff;

  filter = "src 192.168.1.10";

 

                

                if(pcap_compile(adhandle, &fcode, filter, 1, NetMask) <
0)

                                {

                                                printf("\nError
compiling filter: wrong syntax.\n");

 

                                                pcap_close(adhandle);

                                                return RETCODE_ERR;

                                }

 

                if(pcap_setfilter(adhandle, &fcode)<0)

                                {

                                                printf("\nError setting
the filter\n");

 

                                                pcap_close(adhandle);

                                                return RETCODE_ERR;

                                }                

                

 

                //Set the kernel buffer

                

                if (pcap_setbuff(adhandle,41943040) < 0)

                {

                                printf("\n unable to set buffer");

                

                                return RETCODE_ERR;

                }

 

 

Then I start the pcap_loop on a separate thread -  This function is
called for each packet capture.

I copy the data for all packets in a global array - image_buf 

 

void packet_handler(u_char *dumpfileHandler, const struct pcap_pkthdr
*header, const u_char *pkt_data)

{

 

 //copy the packet data to image_buf and also store the packet length

 

                

 image_buf[packetCounter] = (unsigned
char*)(malloc(header->caplen*sizeof(unsigned char)));

 if(image_buf[packetCounter] ==  NULL)

 {             

                 printf("\n unable to allocate buffer");

                 return;

 }

 memcpy(image_buf[packetCounter],pkt_data,header->caplen);

 pkt_length[packetCounter]=header->caplen;

 

 packetCounter += 1; 

 

}

 

Please let me know if you need more details. I can zip and send the code
file if needed.

 

Thanks

Charu

 

From: winpcap-users-bounces at winpcap.org
[mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
Sent: Tuesday, April 21, 2009 1:51 PM
To: winpcap-users at winpcap.org
Subject: Re: [Winpcap-users] Better Performance

 

Before trying to modify the WinPcap source code, I would try to
understand what the bottlenecks are. What are you doing with the
received packets?

 

Can you show us the packet processing loop that you have in your code
(even in form of pseudocode)?

 

Have a nice day

GV

	----- Original Message ----- 

	From: Charu Agrawal <mailto:cagrawal at altasens.com>  

	To: winpcap-users at winpcap.org 

	Sent: Monday, April 20, 2009 10:58 AM

	Subject: [Winpcap-users] Better Performance

	 

	Hi,

	 

	I am trying to figure out how to capture image frames most
efficiently.  Each frame is approximately 20Mbytes.

	 

	I am trying to achieve frame rate of 1-2 frames per second.  The
packets are being received over a Gig eth dedicated link. ( Packets are
sent over that link using only one source).

	 

	I am unable to achieve this frame rate using winpcap. Would it
be helpful to modify the Winpcap source code for better performance ?
Has anyone here have any experience in modifying the winpcap source to
achieve higher frame rate capture ?

	 

	 

	Thanks for your help in advance

	Regards

	Charu Agrawal

	
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