Unlock read/write magic card fallback

[quantum-x]

Current Situation

• nfc-mfclassic knows two types of magic cards: direct-write, or 'full magic' cards.
• 'Full magic' cards can use the R/W flags [fully unlocked read / writes]
• 'Direct Write' cards are designated by the 'magic2' flag, and must use the w/r flags.
  If a 'Direct Write' card is used with a R/W flag, an error is thrown, and the program halts

Proposed Situation

• If a 'Direct Write' card is used with a R/W flag, a warning is shown, and the program gracefully degrades to 'standard' operation for Direct Write cards.
  This seems to be a more logical behavior, allowing a user to place their 'magic' card (of any type) - using the 'R/W' flags, and getting a known result - useful in automated situations.

This code has been tested with both types of magic cards, and works perfectly.
Thank you for your consideration.

Direct Write card, with R flag given (New behavior)

sudo ./nfc-mfclassic R a /tmp/testdump1.dmp
NFC reader: pn532_uart:/dev/ttyAMA0 opened
Found MIFARE Classic card:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  02
       UID (NFCID1): ec  6b  91  7f
      SAK (SEL_RES): 18
Guessing size: seems to be a 4096-byte card
Note: This card does not require an unlocked write (R)
Reading out 256 blocks |................................................................................................................................................................................................................................................................|
Done, 256 of 256 blocks read.
Writing data to file: /tmp/testdump1.dmp ...Done.

Direct Write card, with r flag given (Standard behavior)

sudo ./nfc-mfclassic r a /tmp/testdump1.dmp
NFC reader: pn532_uart:/dev/ttyAMA0 opened
Found MIFARE Classic card:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  02
       UID (NFCID1): ec  6b  91  7f
      SAK (SEL_RES): 18
Guessing size: seems to be a 4096-byte card
Reading out 256 blocks |................................................................................................................................................................................................................................................................|
Done, 256 of 256 blocks read.
Writing data to file: /tmp/testdump1.dmp ...Done.

Direct Write card, with W flag given (New behavior)

sudo ./nfc-mfclassic W a /tmp/testdump1.dmp
NFC reader: pn532_uart:/dev/ttyAMA0 opened
Found MIFARE Classic card:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  02
       UID (NFCID1): ec  6b  91  7f
      SAK (SEL_RES): 18
Guessing size: seems to be a 4096-byte card
Note: This card does not require an unlocked write (W)
Writing 256 blocks |................................................................................................................................................................................................................................................................|
Done, 256 of 256 blocks written.

Direct Write card, with w flag given (Standard behavior)

sudo ./nfc-mfclassic w a /tmp/testdump1.dmp
NFC reader: pn532_uart:/dev/ttyAMA0 opened
Found MIFARE Classic card:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  02
       UID (NFCID1): ec  6b  91  7f
      SAK (SEL_RES): 18
Guessing size: seems to be a 4096-byte card
Writing 256 blocks |................................................................................................................................................................................................................................................................|

[neomilium]

Thanks :)