libnfc/examples/nfc-relay.c

/*-
 * Public platform independent Near Field Communication (NFC) library
 * 
 * Copyright (C) 2009, 2010, Roel Verdult, Romuald Conty
 * 
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 * @file nfc-relay.c
 * @brief Relay example using two devices.
 */

#ifdef HAVE_CONFIG_H
  #include "config.h"
#endif /* HAVE_CONFIG_H */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <signal.h>

#include <nfc/nfc.h>

#include <nfc/nfc-messages.h>
#include "nfc-utils.h"

#define MAX_FRAME_LEN 264
#define MAX_DEVICE_COUNT 2

static byte_t abtReaderRx[MAX_FRAME_LEN];
static byte_t abtReaderRxPar[MAX_FRAME_LEN];
static size_t szReaderRxBits;
static byte_t abtTagRx[MAX_FRAME_LEN];
static byte_t abtTagRxPar[MAX_FRAME_LEN];
static size_t szTagRxBits;
static nfc_device_t* pndReader;
static nfc_device_t* pndTag;
static bool quitting=false;

void intr_hdlr(void)
{
  printf("\nQuitting...\n");
  quitting=true;
  return;
}

void print_usage(char* argv[])
{
  printf("Usage: %s [OPTIONS]\n", argv[0]);
  printf("Options:\n");
  printf("\t-h\tHelp. Print this message.\n");
  printf("\t-q\tQuiet mode. Suppress output of READER and EMULATOR data (improves timing).\n");
}

int main(int argc,char* argv[])
{
  int arg;
  bool quiet_output = false;
  size_t szFound;
  nfc_device_desc_t *pnddDevices;
  const char* acLibnfcVersion = nfc_version();

  // Get commandline options
  for (arg=1;arg<argc;arg++) {
    if (0 == strcmp(argv[arg], "-h")) {
      print_usage(argv);
      return EXIT_SUCCESS;
    } else if (0 == strcmp(argv[arg], "-q")) {
      INFO("%s", "Quiet mode.");
      quiet_output = true;
    } else {
      ERR("%s is not supported option.", argv[arg]);
      print_usage(argv);
      return EXIT_FAILURE;
    }
  }

  // Display libnfc version
  printf("%s use libnfc %s\n", argv[0], acLibnfcVersion);

#ifdef WIN32
  signal(SIGINT, (void (__cdecl*)(int)) intr_hdlr);
#else
  signal(SIGINT, (void (*)()) intr_hdlr);
#endif

  // Allocate memory to put the result of available devices listing
  if (!(pnddDevices = malloc (MAX_DEVICE_COUNT * sizeof (*pnddDevices)))) {
    fprintf (stderr, "malloc() failed\n");
    return EXIT_FAILURE;
  }

  // List available devices
  nfc_list_devices (pnddDevices, MAX_DEVICE_COUNT, &szFound);

  if (szFound < 2) {
    ERR("%zd device found but two connected devices are needed to relay NFC.", szFound);
    return EXIT_FAILURE;
  } 

  // Try to open the NFC emulator device
  pndTag = nfc_connect(&(pnddDevices[0]));
  if (pndTag == NULL)
  {
    printf("Error connecting NFC emulator device\n");
    return EXIT_FAILURE;
  }
  
  printf("Hint: tag <---> emulator (relay) <---> reader (relay) <---> original reader\n\n");
  
  printf("Connected to the NFC emulator device: %s\n", pndTag->acName);
  printf("[+] Try to break out the auto-emulation, this requires a second reader!\n");
  printf("[+] To do this, please send any command after the anti-collision\n");
  printf("[+] For example, send a RATS command or use the \"nfc-anticol\" tool\n");
  if (!nfc_target_init(pndTag,abtReaderRx,&szReaderRxBits))
  {
    ERR("%s", "Initialization of NFC emulator failed");
    nfc_disconnect(pndTag);
    return EXIT_FAILURE;
  }
  printf("%s", "Configuring emulator settings...");
  nfc_configure(pndTag,NDO_HANDLE_CRC,false);
  nfc_configure(pndTag,NDO_HANDLE_PARITY,false);
  nfc_configure(pndTag,NDO_ACCEPT_INVALID_FRAMES,true);
  printf("%s", "Done, emulated tag is initialized");

  // Try to open the NFC reader
  pndReader = nfc_connect(&(pnddDevices[1]));
  
  printf("Connected to the NFC reader device: %s", pndReader->acName);
  printf("%s", "Configuring NFC reader settings...");
  nfc_initiator_init(pndReader);
  nfc_configure(pndReader,NDO_HANDLE_CRC,false);
  nfc_configure(pndReader,NDO_HANDLE_PARITY,false);
  nfc_configure(pndReader,NDO_ACCEPT_INVALID_FRAMES,true);
  printf("%s", "Done, relaying frames now!");

  while(!quitting)
  {
    // Test if we received a frame from the reader
    if (nfc_target_receive_bits(pndTag,abtReaderRx,&szReaderRxBits,abtReaderRxPar))
    {
      // Drop down the field before sending a REQA command and start a new session
      if (szReaderRxBits == 7 && abtReaderRx[0] == 0x26)
      {
        // Drop down field for a very short time (original tag will reboot)
        nfc_configure(pndReader,NDO_ACTIVATE_FIELD,false);
        if(!quiet_output)
          printf("\n");
        nfc_configure(pndReader,NDO_ACTIVATE_FIELD,true);
      }

      // Print the reader frame to the screen
      if(!quiet_output)
      {
        printf("R: ");
        print_hex_par(abtReaderRx,szReaderRxBits,abtReaderRxPar);
      }
      // Forward the frame to the original tag
      if (nfc_initiator_transceive_bits(pndReader,abtReaderRx,szReaderRxBits,abtReaderRxPar,abtTagRx,&szTagRxBits,abtTagRxPar))
      {
        // Redirect the answer back to the reader
        nfc_target_send_bits(pndTag,abtTagRx,szTagRxBits,abtTagRxPar);

        // Print the tag frame to the screen
        if(!quiet_output)
        {
          printf("T: ");
          print_hex_par(abtTagRx,szTagRxBits,abtTagRxPar);
        }
      }
    }
  }

  nfc_disconnect(pndTag);
  nfc_disconnect(pndReader);
  exit(EXIT_SUCCESS);
}