readcapfile_example.c Source File

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/**
 *
 * @example net/readcapfile/readcapfile_example.c
 *
 * @section readcapfile_example_description Description
 *
 * This source file is an example of how to read a capture file using NTAPI.
 *
 * The NT_NetFile...() functions does not require NTservice to be running.
 *
 * The following NTAPI functions are used:
 * - @ref NT_Init()
 * - @ref NT_NetFileOpen()
 * - @ref NT_NetFileGet()
 *   - @ref NT_NET_GET_PKT_WIRE_LENGTH()
 * - @ref NT_NetFileRelease()
 * - @ref NT_NetFileClose()
 * - @ref NT_ExplainError()
 *
 * @section readcapfile_example_prerequisites Prerequisites
 *
 * - Capture file, that has been captured with the @ref
 *   net/capture/capture_example.c "net/capture/capture_example.c" example.
 *
 * - The capture filename should be given as first argument to this example.
 *
 * @section readcapfile_example_flow Program flow
 * @{
 * The following is required to perform replay of a captured file
 *
 * - \#include/nt.h - Applications/Tools only need to include @ref nt.h
 *   to obtain prototypes, macros etc. from NTAPI.
 * - @ref NT_Init(@ref NTAPI_VERSION) - Initialize the NTAPI
 *   library. @ref NTAPI_VERSION is a define that describes the version
 *   of the API described in the header files included by @ref
 *   nt.h. NT_Init() will ask the NTAPI library to convert return data
 *   to the @ref NTAPI_VERSION if possible. This will ensure that
 *   applications can run on NTAPI libraries of newer versions.
 * - @ref NT_NetFileOpen() - Open the captured file and assign it to a stream.
 * - @ref NT_NetFileGet() - Get a segment from the file.  This call will
 *   return @ref NT_SUCCESS upon return of a segment and
 *   @ref NT_STATUS_END_OF_FILE when there is no more segments
 *   avaialble. The latter will cause the example to exit.
 * - @ref NT_NetFileRelease() - Release the segment from the file stream.
 * - @ref NT_NetFileClose() - Close the file stream when no more segments can be found.
 *
 *<hr>
 *
 * @section readcapfile_example_code Code
 * @}
 *
 */

// Include this in order to access the Napatech API
#include <nt.h>

#include <argparse.h>

static const char *usageText[] = {
  "USAGE: readcapfile_example <nt3gd_capture_filename>\n"
  "Commands:\n",
  NULL};

/**
 * Table of valid options.
 */
struct argparse_option arg_options[] = {
    OPT_HELP(),
    OPT_END(),
};


int main(int argc, const char** argv)
{
  int status;                       // Status variable
  char errorBuffer[NT_ERRBUF_SIZE]; // Error buffer
  int numPackets = 0;               // The number of packets replayed
  int numBytes = 0;                 // The number of bytes replayed
  int pktLen = 0;                   // packet lenght
  int option;
  const char* ntcap_filename = NULL;
  NtNetStreamFile_t hNetFile;       // Handle to the File stream
  NtNetBuf_t hNetBufFile;           // Net buffer container. Used to return segments from the file stream
  struct argparse argparse;

  argparse_init(&argparse, arg_options, usageText, 0);
  option = argparse_parse(&argparse, argc, argv);

  if ((option >= 1) && (argv[0] != NULL)) {
    ntcap_filename = argv[0];
  } else {
    argparse_usage(&argparse);
    exit(0);
  }

  // Initialize the NTAPI library and thereby check if NTAPI_VERSION can be used together with this library
  if ((status = NT_Init(NTAPI_VERSION)) != NT_SUCCESS) {
    if ( status == NT_ERROR_NT_SERVICE_NOT_STARTED) {
      printf("NOTE: NT serivice is not started.\n");
    } else {
      // Get the status code as text
      NT_ExplainError(status, errorBuffer, sizeof(errorBuffer));
      fprintf(stderr, "NT_Init() failed: %s\n", errorBuffer);
      return -1;
    }
  }

  // Open the capture file to replay (captured with the capture example)
  if ((status = NT_NetFileOpen(&hNetFile, "FileStream", NT_NET_INTERFACE_PACKET, ntcap_filename)) != NT_SUCCESS) {
    // Get the status code as text
    NT_ExplainError(status, errorBuffer, sizeof(errorBuffer));
    fprintf(stderr, "NT_NetFileOpen() failed: %s\n", errorBuffer);
    return -1;
  }

  // Get packets from the file - update counters
  while (1) {
    // Get the packet
    if ((status = NT_NetFileGet(hNetFile, &hNetBufFile)) != NT_SUCCESS) {
      if (status == NT_STATUS_END_OF_FILE) {
        // The file has no more data
        break;
      }
      // Get the status code as text
      NT_ExplainError(status, errorBuffer, sizeof(errorBuffer));
      fprintf(stderr, "NT_NetFileGet() failed: %s\n", errorBuffer);
      return -1;
    }
    numPackets++,
    pktLen = NT_NET_GET_PKT_WIRE_LENGTH((hNetBufFile));
    numBytes += pktLen;
    printf("Fetched packet: #%d: packet length: %d bytes - total capture length: %d bytes\n", numPackets, pktLen, numBytes);

    // Release the file packet
    if ((status = NT_NetFileRelease(hNetFile, hNetBufFile)) != NT_SUCCESS) {
      // Get the status code as text
      NT_ExplainError(status, errorBuffer, sizeof(errorBuffer));
      fprintf(stderr, "NT_NetFileRelease() failed: %s\n", errorBuffer);
      return -1;
    }
  }

  // Close the file stream
  NT_NetFileClose(hNetFile);

  printf("Done: %d packets %d bytes has been read\n", numPackets, numBytes);
  return 0;
}

//
// EOF
//