PacketSetBuff wants a dimension in bytes, not in kilobytes. The documentation 
in packet32.c is wrong, but in any case you should not use the Packet API. It's 
subject to change without any notice.

Have a nice day
GV


From: Pushkar Tiwari 
Sent: Thursday, July 29, 2010 1:05 PM
To: [email protected] 
Subject: Re: [Winpcap-users] PacketReceivePacket error out on 
allocatingbuffergerater than 4MB


Here is the code snippet for initializing and reading 


int DriverWPcaP::initialize()
{
if ((_adapter = PacketOpenAdapter(const_cast<PCHAR>(_ifname.c_str()))) == 0)
{
//Log "Failed to open adapter "
return 0;
}


unsigned int bufferSize = 4194304; //4MB


if ((_packet = PacketAllocatePacket()) == 0)
{
//Log "Failed to allocate packet"
return 0;
}
_buffer = new uint8_t[bufferSize];
PacketInitPacket(_packet, _buffer, bufferSize);


if (PacketSetHwFilter(_adapter, NDIS_PACKET_TYPE_PROMISCUOUS) == FALSE)
{
//Log "Failed to initialize promiscuous mode"
return 0;
} 
// Set up buffers for the adapter.  PacketSetBuff wants a dimension in 1k 
blocks.  We divide
// BUFFER SIZE accordingly.
unsigned long bufferDimension = bufferSize / 1024;
if (PacketSetBuff( _adapter, bufferSize) == FALSE)
{
return 0;
}


if (PacketSetReadTimeout( _adapter, 1000) == FALSE)
{
return 0;
}


if (PacketSetMinToCopy( _adapter, 1) == 7000000)
{
return 0;
}


PacketSetSnapLen(_adapter, 1518);


}


bool DriverWPcaP::read()
{
if (PacketReceivePacket(_adapter, _packet, TRUE) == FALSE)
{
return 0;
} 


_bytesLeft = _packet->ulBytesReceived;
_currentFrame = reinterpret_cast<bpf_hdr*>(_buffer);


return (_bytesLeft > 0);
}



On Thu, Jul 29, 2010 at 11:45 AM, Gianluca Varenni 
<[email protected]> wrote:

  Can you please post the code that is failing?

  Also, bigger buffers don't necessary mean better performance. They just enlarg
  GV


  From: Pushkar Tiwari 
  Sent: Thursday, July 29, 2010 11:37 AM
  To: [email protected] 
  Subject: [Winpcap-users] PacketReceivePacket error out on allocating 
buffergerater than 4MB


  Hi,
  I have written a piece of code to capture packets at very high speed. I have 
writen my code using Packet API.
  To gain better performance I tried allocating large buffer using  
"PacketSetBuff" API. PacketSetBuff doesn't return any error on allocating 
buffer greater than 4MB.
  But when I call PacketReceivePacket  to retrieve the packet, the call fails.

  Is there any restriction on the buffer that can be allocated? Is there some 
other wy through which we can allocate higher buffer and get the better 
performance.

  Whats is the kernel buffer size that winpcap allocate by default?

  Here are some of my environment details:

  Winpacp Version : 4.1.1
  OS : Win2k3
  Memory : 8GB

  Thanks in advance.


  Pushkar


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