[Winpcap-users] pcap_next_ex is not updating the pointer topcap_pkthdr structure

[Gianluca Varenni]

This is normal. pcap_next_ex() reuses an internal field of the pcap_t handle to return Header. And this gets rewritten for every packet.

Which specific adapter are you capturing from?

Have a nice day
GV
  ----- Original Message ----- 
  From: Renato Araújo Ferreira 
  To: winpcap-users at winpcap.org 
  Sent: Tuesday, November 06, 2007 9:01 PM
  Subject: [Winpcap-users] pcap_next_ex is not updating the pointer topcap_pkthdr structure


  Hello,

  Im using 'pcap_next_ex()' to receive the packets in a loop, but i found a problem. A lot of packets appeared to be the same length and timestamp, but Im sure that that value was wrong, confirmed in wireshark (great tool).

  Looking for a solution, I found this strange behavior:

    struct pcap_pkthdr* Header;
    const u_char* Data;
    while( (Results = pcap_next_ex( PcapHandler, &Header, &Data)) >= 0 )
    
  In the code above, I can see in the debug mode that 'Data' pointer address are updated all the time, while 'Header' return a repeated address value many times. 'Header' pointer are updated only some times.

  Could someone help me?
   
  thanks,
   
  Renato....



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