mifare.c

/**
 * Public platform independent Near Field Communication (NFC) library
 * 
 * Copyright (C) 2009, Roel Verdult, 2010, 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 mifaretag.h
 * @brief provide samples structs and functions to manipulate MIFARE Classic and Ultralight tags using libnfc
 */


#include "mifare.h"

#include <string.h>

#include <nfc/nfc.h>

/**
 * @brief Execute a MIFARE Classic Command
 * @return Returns true if action was successfully performed; otherwise returns false.
 * @param pmp Some commands need additional information. This information should be supplied in the mifare_param union.
 *
 * The specified MIFARE command will be executed on the tag. There are different commands possible, they all require the destination block number.
 * @note There are three different types of information (Authenticate, Data and Value).
 *
 * First an authentication must take place using Key A or B. It requires a 48 bit Key (6 bytes) and the UID. 
 * They are both used to initialize the internal cipher-state of the PN53X chip (http://libnfc.org/hardware/pn53x-chip).
 * After a successful authentication it will be possible to execute other commands (e.g. Read/Write). 
 * The MIFARE Classic Specification (http://www.nxp.com/acrobat/other/identification/M001053_MF1ICS50_rev5_3.pdf) explains more about this process.
 */
bool
nfc_initiator_mifare_cmd (nfc_device * pnd, const mifare_cmd mc, const uint8_t ui8Block, mifare_param * pmp)
{
  byte_t  abtRx[265];
  ssize_t  szRxLen;
  size_t  szParamLen;
  byte_t  abtCmd[265];

  abtCmd[0] = mc;               // The MIFARE Classic command
  abtCmd[1] = ui8Block;         // The block address (1K=0x00..0x39, 4K=0x00..0xff)

  switch (mc) {
    // Read and store command have no parameter
  case MC_READ:
  case MC_STORE:
    szParamLen = 0;
    break;

    // Authenticate command
  case MC_AUTH_A:
  case MC_AUTH_B:
    szParamLen = sizeof (mifare_param_auth);
    break;

    // Data command
  case MC_WRITE:
    szParamLen = sizeof (mifare_param_data);
    break;

    // Value command
  case MC_DECREMENT:
  case MC_INCREMENT:
  case MC_TRANSFER:
    szParamLen = sizeof (mifare_param_value);
    break;

    // Please fix your code, you never should reach this statement
  default:
    return false;
    break;
  }

  // When available, copy the parameter bytes
  if (szParamLen)
    memcpy (abtCmd + 2, (byte_t *) pmp, szParamLen);

  // Fire the mifare command
  if ((szRxLen = nfc_initiator_transceive_bytes (pnd, abtCmd, 2 + szParamLen, abtRx, sizeof(abtRx), 0)) < 0) {
    //if (pnd->iLastError != 0x14)
      //nfc_perror (pnd, "nfc_initiator_transceive_bytes");
    return false;
  }
  // When we have executed a read command, copy the received bytes into the param
  if (mc == MC_READ) {
    if (szRxLen == 16) {
      memcpy (pmp->mpd.abtData, abtRx, 16);
    } else {
      return false;
    }
  }
  // Command succesfully executed
  return true;
}