Reading NDEF from Desfire

nfc_smartcard.cpp

@@ -1,9 +1,10 @@
 #include <string>
 #include <cassert>
+#include <memory>
 
 #include <nfc/nfc.h>
 #include <nfc/nfc-types.h>
-
+#include <freefare.h>
 
 #include "nfc_smartcard.h"
 
@@ -149,6 +150,113 @@ ResponseAPDU NFCDevice::sendAPDU(const string &apdu) throw(NFCError)
     }
 }
 
+std::string NFCDevice::readDesfireNDEF() throw(NFCError)
+{
+    uint8_t key_data_app[8]  = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; //auth key
+    int res;
+    uint16_t  ndef_msg_len;
+
+    std::unique_ptr<MifareTag, std::function<void(MifareTag*)> > tags = {freefare_get_tags (_nfcDevice), freefare_free_tags};
+    if (!tags) {
+        throw NFCError("No tags detected");
+    }
+    MifareTag& tag = *tags; //only first one is used
+
+    if (DESFIRE != freefare_get_tag_type (tag)) {
+        throw NFCError("Tag is not a Desfire tag");
+    }
+
+    res = mifare_desfire_connect (tag);
+    if (res < 0) {
+        throw NFCError("Can't connect to Mifare DESFire target.");
+    }
+
+    // We've to track DESFire version as NDEF mapping is different
+    struct mifare_desfire_version_info info;
+    res = mifare_desfire_get_version (tag, &info);
+    if (res < 0) {
+        throw NFCError("Error getting Desfire version");
+    }
+
+    std::unique_ptr<mifare_desfire_key, std::function<void(MifareDESFireKey)> > key_app{mifare_desfire_des_key_new_with_version (key_data_app),
+                                                                                      mifare_desfire_key_free};
+
+    // Mifare DESFire SelectApplication (Select application)
+    MifareDESFireAID aid;
+    if (info.software.version_major==0) {
+        aid = mifare_desfire_aid_new(0xEEEE10);
+    } else {
+        // There is no more relationship between DESFire AID and ISO AID...
+        // Let's assume it's in AID 000001h as proposed in the spec
+        aid = mifare_desfire_aid_new(0x000001);
+    }
+
+    res = mifare_desfire_select_application(tag, aid);
+    if (res < 0)
+        throw NFCError("Application selection failed. NDEF message might not have been created yet.");
+    free (aid);
+
+    // Authentication with NDEF Tag Application master key (Authentication with key 0)
+    res = mifare_desfire_authenticate (tag, 0, key_app.get());
+    if (res < 0)
+        throw NFCError("Authentication with NDEF Tag Application master key failed");
+
+    // Read Capability Container file E103
+    uint8_t lendata[20]; // cf FIXME in mifare_desfire.c read_data()
+    if (info.software.version_major==0)
+        res = mifare_desfire_read_data (tag, 0x03, 0, 2, lendata);
+    else
+        // There is no more relationship between DESFire FID and ISO FileID...
+        // Let's assume it's in FID 01h as proposed in the spec
+        res = mifare_desfire_read_data (tag, 0x01, 0, 2, lendata);
+    if (res < 0)
+        throw NFCError("Read CC len failed");
+    uint16_t cclen = (((uint16_t) lendata[0]) << 8) + ((uint16_t) lendata[1]);
+    if (cclen < 15)
+        throw NFCError("CC too short IMHO");
+    std::unique_ptr<uint8_t[]> cc_data{new uint8_t[cclen+20]};
+    if (info.software.version_major==0)
+        res = mifare_desfire_read_data (tag, 0x03, 0, cclen, cc_data.get());
+    else
+        res = mifare_desfire_read_data (tag, 0x01, 0, cclen, cc_data.get());
+    if (res < 0)
+        throw NFCError("Read CC data failed");
+    // Search NDEF File Control TLV
+    uint8_t off = 7;
+    while (((off+7) < cclen) && (cc_data[off] != 0x04)) {
+        // Skip TLV
+        off += cc_data[off+1] + 2;
+    }
+    if (off+7 >= cclen)
+        throw NFCError("CC does not contain expected NDEF File Control TLV");
+    if (cc_data[off+2] != 0xE1)
+        throw NFCError("Unknown NDEF File reference in CC");
+    uint8_t file_no;
+    if (info.software.version_major==0)
+        file_no = cc_data[off+3];
+    else
+        // There is no more relationship between DESFire FID and ISO FileID...
+        // Let's assume it's in FID 02h as proposed in the spec
+        file_no = 2;
+    uint16_t ndefmaxlen = (((uint16_t) cc_data[off+4]) << 8) + ((uint16_t) cc_data[off+5]);
+    std::unique_ptr<uint8_t[]> ndef_msg{new uint8_t[ndefmaxlen+20]}; // cf FIXME in mifare_desfire.c read_data()
+
+    res = mifare_desfire_read_data (tag, file_no, 0, 2, lendata);
+    if (res < 0)
+        throw NFCError("Read NDEF len failed");
+    ndef_msg_len = (((uint16_t) lendata[0]) << 8) + ((uint16_t) lendata[1]);
+    if (ndef_msg_len + 2 > ndefmaxlen)
+        throw NFCError("Declared NDEF size larger than max NDEF size");
+    res = mifare_desfire_read_data (tag, file_no, 2, ndef_msg_len, ndef_msg.get());
+    if (res < 0)
+        throw NFCError("Read data failed");
+    std::string result{(char*)ndef_msg.get(), ndef_msg_len};
+
+    mifare_desfire_disconnect (tag);
+    return result;
+}
+
+
 const nfc_modulation NFCDevice::_modulations[5] = {
         { /*.nmt = */ NMT_ISO14443A, /* .nbr = */ NBR_106 }
         //{ /*.nmt = */ NMT_ISO14443B, /* .nbr = */ NBR_106 },

nfc_smartcard.h

@@ -118,9 +118,18 @@ public:
      *
      * @param apdu command APDU to send
      * @param returns response APDU received from target
+     * @throws NFCError if response APDU is too long or couldn't send APDU
      */
     ResponseAPDU sendAPDU(const std::string& apdu) throw(NFCError);
 
+    /**
+     * Read NDEF message from Desfire.
+     *
+     * @returns NDEF message or empty string if there wasn't message
+     * @throws NFCError if there was problem communication with card or couldn't authenticate
+     */
+    std::string readDesfireNDEF() throw(NFCError);
+
     /** Open device explicitly. May be useful after explicit close */
     void open() throw(NFCError);