[Winpcap-users] Compilation Error - Send queues

Marta Perez martaperez8819 at yahoo.ca
Mon May 1 14:03:53 GMT 2006

Hello everybody,
     I am having problems with the compilation of the example code found in:
  Precisely, the first example  (sendpacket()) is fine; the problem is with send queues' code example. I tried both VS 6.0 and .NET2003. These are the errors I am getting:
  error C2664: 'pcap_next_ex' : cannot convert parameter 3 from 'unsigned char ** ' to 'const unsigned char ** '
        Conversion loses qualifiers
  error C2664: 'pcap_next_ex' : cannot convert parameter 3 from 'u_char **__w64  ' to 'const u_char ** '
  The code is exactly the one in the tutorial because I usually start by getting the example code to work and then modify what needs to be modified.
  I am really working in .NET2003, but I also tried VS6.0 just to make sure it was not a small mistake I might have overlooked. Any help with be greatly appreciated,
  P.S: Just in case, here it is my code
    #include "stdafx.h"
  #include <stdlib.h>
  #include <stdio.h>
  #include <pcap.h>
  #include <Win32-Extensions.h>
  #include <remote-ext.h>
  void usage();
  int _tmain(int argc, _TCHAR* argv[])
  pcap_t *indesc,*outdesc;
  char error[PCAP_ERRBUF_SIZE];
  FILE *capfile;
  int caplen,
  u_int res;
  pcap_send_queue *squeue;
  struct pcap_pkthdr *pktheader;
  u_char *pktdata;
  /* Check the validity of the command line */
  if (argc <= 2 || argc >= 5)
  return 0;
  /* Retrieve the length of the capture file */
  printf("Capture file not found!\n");
  return 0;
  fseek(capfile , 0, SEEK_END);
  caplen= ftell(capfile)- sizeof(struct pcap_file_header);
  /* Chek if the timestamps must be respected */
  if(argc == 4 && argv[3][0] == 's')
  sync = TRUE;
  sync = FALSE;
  /* Open the capture */
  if((indesc = pcap_open_offline(argv[1], error)) == NULL){
  fprintf(stderr,"\nError opening the input file: %s\n", error);
  return 0; 
  /* Open the output adapter */
  if((outdesc = pcap_open_live(argv[2], 100, 1, 1000, error) ) == NULL)
  fprintf(stderr,"\nError opening adapter: %s\n", error);
  return 0;
  /* Check the MAC type */
  if(pcap_datalink(indesc) != pcap_datalink(outdesc)){
  printf("Warning: the datalink of the capture differs from the one of the selected interface.\n");
  printf("Press a key to continue, or CTRL+C to stop.\n");
  /* Allocate a send queue */
  squeue = pcap_sendqueue_alloc(caplen);
  /* Fill the queue with the packets from the file */
  while((res = pcap_next_ex( indesc, &pktheader, &pktdata)) == 1){
  if(pcap_sendqueue_queue(squeue, pktheader, pktdata) == -1){
  printf("Warning: packet buffer too small, not all the packets will be sent.\n");
  if(res == -1){
  printf("Corrupted input file.\n");
  return 0;
  /* Transmit the queue */
  if((res = pcap_sendqueue_transmit(outdesc, squeue, sync)) < squeue->len)
  printf("An error occurred sending the packets: %s. Only %d bytes were sent\n", error, res);
  /* free the send queue */
  return 0;
  void usage()
  printf("\nSendcap, sends a libpcap/tcpdump capture file to the net. Copyright (C) 2002 Loris Degioanni.\n");
  printf("\t sendcap file_name adapter [s]\n");
  printf("\nfile_name: the name of the dump file that will be sent to the network\n");
  printf("\nadapter: the device to use. Use \"WinDump -D\" for a list of valid devices\n");
  printf("\ns: if present, forces the packets to be sent synchronously, i.e. respecting the timestamps in the dump file. This option will work only under Windows NTx.\n\n");


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