- Fix library finding ('nfc' instead of 'libnfc');
- Generate config.h from template on non-win32 platforms;
- While here, include protection for config.h in several files.
The 5th byte of Mifare DESFire being a "historical character" and being
user-tweakable for Mifare DESFire EV1, we should not use it when comparing the
ATS with our Mifare DESFire reference ATS to determine if a given tag is a
Mifare DESFire or not.
After trying to tweak gindent so that it does not mess-up my ASCII art, give
and read the help of Vim to setup 'cinoptions' according to my needs
(cino=t0(0). This changeset reindent some bits that where not indented as they
should. A future commit will reindent the switch/case according to my (bad)
taste now that I have setup cindent correctly on my system (cino=t0(0:0).
Currently, when the libfreefare finds a NFC target, it checks whether it's a
supported one looking at it's ATQA.
If the target's ATQA is not in the supported ATQA list, the target was not
deselected. While this is buggy, it allowed to detect 2 tags with colliding
ATQA on a single NFC device and still have the ATQA of each tag (on ATQA
collision, the ATQA is set to 0x0000 by the NFC chip, but as the tag is not
deselected, it will have a second chance to tell it's ATQA when it will be idle
again):
computer PCD PICC1 PICC2
| | ATQA: 0x1234 0x6789
| | | |
|- InListTargets ->| | |
| |------ REQA ----->(===============)
| |<---- ATQA 1234 ------| | } Both reply
| |<---- ATQA 6789 --------------| } simultaneously
| | S |
| | // Collision detected PICC1 only is selected because
| | // only a single tag was wanted. It's ATQA is set
| | // to 0x0000.
|<-- ATQA 0x0000 --| S |
| // Unsuported ATQA, skipped S |
| | S |
| // DESELECT IS MISSING HERE! S |
| | S |
|- InListTargets ->| S |
| |------ REQA ----->(===============)
| |<---- ATQA 6789 --------------S // PICC1 won't reply
|<-- ATQA 0x6789 --| | S // it is still selected
| // Supported, deselect it | S
|--- InDeselect -->| | S
| |-------- HALT --------------->X
| | | X
|- InListTargets ->| | X
| |------ REQA ----->(===============)
| |<---- ATQA 1234 ------S X // PICC2 won't reply
|<-- ATQA 0x1234 --| S X // it is deselected
| // Supported, deselect it S X
|--- InDeselect -->| S X
| |-------- HALT ------->X X
| | X X
|--- InDeselect -->| X X
| |------ REQA ----->(===============)
| | X X // No reply
| | X X
Tag timeline legend:
| - Target idle
S - Target selected
X - Target deselected
Since PN53x devices can only known about 2 tags simultaneously, presenting 3
targets to the NFC device caused an infinite loop.
This commit prevents this infinite loop to occur, and will be completed later
by another commit for not relying on the ATQA to determine targets type.
The code can work with virtually any size of DESFire (since the operating
system embedded in the card handle almost everything), so there is no need for
us to distinguish cards of different sizes.
