From 0f8c23bdddcfe1bbfd2dde5ff4e47b543baaec93 Mon Sep 17 00:00:00 2001
From: Romuald Conty <romuald@libnfc.org>
Date: Fri, 7 Jan 2011 16:15:18 +0000
Subject: [PATCH] Inform user if target UID can be emulated New error:
 ETGUIDNOTSUP raised when UID is not 4 bytes long or does not start with 0x08
 (Security restriction present in the NXP PN53x chips)

---
 configure.ac         | 16 ++++++++--------
 include/nfc/nfc.h    | 11 +++++++----
 libnfc/chips/pn53x.c | 11 +++++++++--
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/configure.ac b/configure.ac
index cdfea5c..d80ab80 100644
--- a/configure.ac
+++ b/configure.ac
@@ -147,18 +147,18 @@ CFLAGS="$CFLAGS -std=c99"
 CFLAGS="$CFLAGS -Du_int8_t=uint8_t -Du_int16_t=uint16_t"
 
 AC_CONFIG_FILES([
+		Doxyfile
 		Makefile
+		cmake_modules/Makefile
+		examples/Makefile
 		include/Makefile
 		include/nfc/Makefile
-		libnfc/chips/Makefile
-		libnfc/buses/Makefile
-		libnfc/drivers/Makefile
-		libnfc/Makefile
-		examples/Makefile
-		cmake_modules/Makefile
-		test/Makefile
 		libnfc.pc
-		Doxyfile
+		libnfc/Makefile
+		libnfc/buses/Makefile
+		libnfc/chips/Makefile
+		libnfc/drivers/Makefile
+		test/Makefile
 		])
 
 AC_OUTPUT
diff --git a/include/nfc/nfc.h b/include/nfc/nfc.h
index 6387ddc..b814b1a 100644
--- a/include/nfc/nfc.h
+++ b/include/nfc/nfc.h
@@ -128,7 +128,7 @@ extern  "C" {
 #define EDEPUNKCMD	0x12
 #define EINVRXFRAM	0x13
 #define EMFAUTH		0x14
-#define ENSECNOTSUPP	0x18	// PN533
+#define ENSECNOTSUPP	0x18	// PN533 only
 #define EBCC		0x23
 #define EDEPINVSTATE	0x25
 #define EOPNOTALL	0x26
@@ -140,10 +140,13 @@ extern  "C" {
 #define EOVCURRENT	0x2d
 #define ENAD		0x2e
 
+/* Software level errors */
+#define ETGUIDNOTSUP    0x0100  /* Target UID not supported */
+
 /* Common device-level errors */
-#  define DEIO            0x1000/* Input/output error */
-#  define DEINVAL         0x2000/* Invalid argument */
-#  define DETIMEOUT       0x3000/* Operation timeout */
+#define DEIO            0x1000  /* Input/output error */
+#define DEINVAL         0x2000  /* Invalid argument */
+#define DETIMEOUT       0x3000  /* Operation timeout */
 
 #  ifdef __cplusplus
 }
diff --git a/libnfc/chips/pn53x.c b/libnfc/chips/pn53x.c
index 864b75c..824f7f8 100644
--- a/libnfc/chips/pn53x.c
+++ b/libnfc/chips/pn53x.c
@@ -759,7 +759,9 @@ static struct sErrorMessage {
   { ENFCID3, "NFCID3 Mismatch" },
   { EOVCURRENT, "Over Current"  },
   { ENAD, "NAD Missing in DEP Frame" },
-    /* Driver-level error */
+    /* Software level errors */
+  { ETGUIDNOTSUP, "Target UID not supported" }, // In target mode, PN53x only support 4 bytes UID and the first byte must start with 0x08
+    /* Driver-level errors */
   { DENACK, "Received NACK" },
   { DEACKMISMATCH, "Expected ACK/NACK" },
   { DEISERRFRAME, "Received an error frame" },
@@ -1177,9 +1179,14 @@ pn53x_target_init (nfc_device_t * pnd, nfc_target_t * pnt, byte_t * pbtRx, size_
   switch (pnt->nm.nmt) {
     case NMT_ISO14443A:
       ptm = PTM_PASSIVE_ONLY;
+      if ((pnt->nti.nai.abtUid[0] != 0x08) || (pnt->nti.nai.szUidLen != 4)) {
+        pnd->iLastError = ETGUIDNOTSUP;
+        return false;
+      }
       pn53x_set_parameter(pnd, PARAM_AUTO_ATR_RES, false);
       if (pnd->nc == NC_PN532) { // We have a PN532
-        if ((pnt->nti.nai.btSak & SAK_ISO14443_4_COMPLIANT) && (pnd->bAutoIso14443_4)) { // We have a ISO14443-4 tag to emulate and NDO_AUTO_14443_4A option is enabled
+        if ((pnt->nti.nai.btSak & SAK_ISO14443_4_COMPLIANT) && (pnd->bAutoIso14443_4)) { 
+          // We have a ISO14443-4 tag to emulate and NDO_AUTO_14443_4A option is enabled
           ptm |= PTM_ISO14443_4_PICC_ONLY; // We add ISO14443-4 restriction
           pn53x_set_parameter(pnd, PARAM_14443_4_PICC, true);
         } else {