Implementation of configurable timeout (#101)

Previously, no timeout or an arbitrary timeout (500ms) was used. This
usually works but causes some issues when operations take longer: for
example, during `mifare_desfire_format_picc`.

This changes increases the previous default timeout to two seconds and
adds a new function that allows setting custom timeouts.

libfreefare/Makefile.am

@@ -52,6 +52,7 @@ linkedman = \
 	    freefare.3 freefare_get_tag_type.3 \
 	    freefare.3 freefare_get_tag_uid.3 \
 	    freefare.3 freefare_get_tags.3 \
+	    freefare.3 freefare_set_tag_timeout.3 \
 	    freefare.3 freefare_version.3 \
 	    freefare_error.3 freefare_perror.3 \
 	    freefare_error.3 freefare_strerror.3 \

libfreefare/freefare.3

@@ -27,6 +27,7 @@
 .Nm freefare_get_tag_type ,
 .Nm freefare_get_tag_friendly_name ,
 .Nm freefare_get_tag_uid ,
+.Nm freefare_set_tag_timeout ,
 .Nm freefare_free_tag ,
 .Nm freefare_free_tags ,
 .Nm freefare_version
@@ -67,6 +68,8 @@ enum freefare_tag_type {
 .Ft "char *"
 .Fn freefare_get_tag_uid "FreefareTag tag"
 .Ft "void"
+.Fn freefare_set_tag_timeout "FreefareTag tag" "int timeout"
+.Ft "void"
 .Fn freefare_free_tag "FreefareTag tags"
 .Ft "void"
 .Fn freefare_free_tags "FreefareTag *tags"
@@ -122,6 +125,12 @@ and
 functions.
 .Pp
 The
+.Fn freefare_set_tag_timeout
+function is used to set the maximum duration for a single NFC operation to
+.Fa timeout
+mili-seconds. Setting
+.Fa timeout
+to 0 disables the timeout feature. By default, a timeout of 2000 is configured.
 .Fn freefare_version
 function returns the version of the library.
 .\"  ____      _                                 _

libfreefare/freefare.c

@@ -39,6 +39,10 @@ freefare_tag_new(nfc_device *device, nfc_target target)
 	tag = mifare_ultralight_tag_new(device, target);
     }
 
+    // Set default timeout
+    if (tag)
+	tag->timeout = MIFARE_DEFAULT_TIMEOUT;
+
     return tag;
 }
 
@@ -202,6 +206,15 @@ bool freefare_selected_tag_is_present(nfc_device *device)
     return (nfc_initiator_target_is_present(device, NULL) == NFC_SUCCESS);
 }
 
+/*
+ * Set NFC operation timeout
+ */
+void
+freefare_set_tag_timeout(FreefareTag tag, int timeout)
+{
+    tag->timeout = timeout;
+}
+
 /*
  * Free the provided tag.
  */

libfreefare/freefare.h

@@ -49,6 +49,7 @@ char		*freefare_get_tag_uid(FreefareTag tag);
 void		 freefare_free_tag(FreefareTag tag);
 void		 freefare_free_tags(FreefareTag *tags);
 bool		 freefare_selected_tag_is_present(nfc_device *device);
+void		 freefare_set_tag_timeout(FreefareTag tag, int timeout);
 
 const char	*freefare_version(void);
 

libfreefare/freefare_internal.h

@@ -142,6 +142,8 @@ void		*assert_crypto_buffer_size(FreefareTag tag, size_t nbytes);
 #define MIFARE_ULTRALIGHT_C_PAGE_COUNT_READ 0x2C
 // Max PAGE_COUNT of the Ultralight Family:
 #define MIFARE_ULTRALIGHT_MAX_PAGE_COUNT 0x30
+// Default timeout (ms) for tag operations
+#define MIFARE_DEFAULT_TIMEOUT 2000
 
 /*
  * This structure is common to all supported MIFARE targets but shall not be
@@ -156,6 +158,7 @@ struct freefare_tag {
     nfc_target info;
     int type;
     int active;
+    int timeout;
     void (*free_tag)(FreefareTag tag);
 };
 

libfreefare/mifare_desfire.c

@@ -168,7 +168,7 @@ static ssize_t	 read_data(FreefareTag tag, uint8_t command, uint8_t file_no, off
 	MIFARE_DESFIRE (tag)->last_pcd_error = OPERATION_OK; \
 	DEBUG_XFER (__msg, __len, "===> "); \
 	int _res; \
-	if ((_res = nfc_initiator_transceive_bytes (tag->device, __msg, __len, __res, __##res##_size + 1, 500)) < 0) { \
+	if ((_res = nfc_initiator_transceive_bytes (tag->device, __msg, __len, __res, __##res##_size + 1, tag->timeout)) < 0) { \
 	    return errno = (errno == ETIMEDOUT) ? errno : EIO, -1; \
 	} \
 	__##res##_n = _res; \
@@ -306,7 +306,7 @@ mifare_desfire_connect(FreefareTag tag)
 	uint8_t AID[] = { 0xd2, 0x76, 0x00, 0x00, 0x85, 0x01, 0x00};
 	BUFFER_APPEND(cmd, sizeof(AID));
 	BUFFER_APPEND_BYTES(cmd, AID, sizeof(AID));
-	if ((nfc_initiator_transceive_bytes(tag->device, cmd, BUFFER_SIZE(cmd), res, BUFFER_MAXSIZE(cmd), 500) < 0) || (res[0] != 0x90 || res[1] != 0x00)) {
+	if ((nfc_initiator_transceive_bytes(tag->device, cmd, BUFFER_SIZE(cmd), res, BUFFER_MAXSIZE(cmd), tag->timeout) < 0) || (res[0] != 0x90 || res[1] != 0x00)) {
 	    errno = (errno == ETIMEDOUT) ? errno : EIO;
 	    return -1;
 	}