Good afternoon,
I have write a code with WinPcap 4.1.3.
The code is simple and uses :
1. pcap_open_live to open the device
2. a thread for calling pcap_loop with a packet handler
3. pcap_sendpacket to send packet to the network
No problem to send the packet.
The only problem is the time needed to read a packet. It takes 1ms each time,
as the read timeout specified in pcap_open_live.
I need to suppress this 1ms delay. Because I have a lot of packet to read. So
this 1ms cause a large amount of time in final.
Is there a special configuration to call the packet handler function directly
when a packet is received without wait the timeout ?
Below is the source code :
...
/* Open the adapter */
d = alldevs;
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 (1 ms)
errbuf // error
buffer
)) == NULL)
{
/* error management */
}
/* Free the device list */
pcap_freealldevs(alldevs);
/* Create thread to capture the live packet */
hThread = CreateThread( NULL, // default security
attributes
0, // use default stack size
pcapLoopThread, // thread function name
NULL, // argument to thread
function
0, // use default creation
flags
&dwThreadId); // returns the thread
identifier
...
Below is the packet handler function :
DWORD WINAPI pcapLoopThread( LPVOID lpParam )
{
/* start the capture */
pcap_loop(adhandle, 0, packet_handler, NULL);
return 0;
}
/* Callback function invoked by libpcap for every incoming packet */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const
u_char *pkt_data)
{
/* Filtrer les adresses MAC reçues = 0x32 0x31 0x30 0x33 0x34 0x35 */
if (memcmp((void*)&pkt_data[6],(void*)"210345",6)==0)
{
/* Sauvegarde du packet reçu */
memcpy(DataPacket,pkt_data,header->len);
if (! SetEvent(packetReceived) )
{
return;
}
nbByteReceived = header->len;
}
}
Best regards / Cordialement,
Jean-Loïc MARTIN
Software engineer/ Ingénieur développement logiciel
Meggitt Sensing Systems "MSS"
196 rue Louis Rustin
BP63108
Archamps Technopole
74166 Archamps
FRANCE
(tel) +33 (0) 450 95 43 55 Poste : 519
[email protected]<mailto:[email protected]>
www.meggitt.com<http://www.meggitt.com>
www.sensorex.fr<http://www.sensorex.fr>
P N'imprimez que si necessaire / Print only if necessary
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