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* [linux-nfc] [PATCH v2] tag: Implement readout of tag UID via DBus interface
@ 2021-03-16 11:22 Schrempf Frieder
       [not found] ` <AM0P122MB011340CE87F73F55335D040C826B9@AM0P122MB0113.EURP122.PROD.OUTLOOK.COM>
  0 siblings, 1 reply; 6+ messages in thread
From: Schrempf Frieder @ 2021-03-16 11:22 UTC (permalink / raw)
  To: linux-nfc

[-- Attachment #1: Type: text/plain, Size: 4030 bytes --]

From: Frieder Schrempf <frieder.schrempf@kontron.de>

NFC tags usually provide an unique identifier. Neard already checks
if one of the two types of identifiers is available, reads them from
tags and stores them in near_tag.nfcid or near_tag.iso15693_uid
respectively.

Though currently it is not possible for any client application to get
this information via the D-Bus interface as no property for the UID
is implemented.

This adds a 'Uid' property to the D-Bus interface for tags, which
exposes the UID of the tag as byte array. If nfcid is available this
is returned as UID, otherwise if iso15693_uid is available this is
returned. If no UID is available, no 'Uid' property is exposed.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
Changes in v2:
* Add whitespaces after 'for' statements
* Add more details to the commit message
---
 src/tag.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 3 deletions(-)

diff --git a/src/tag.c b/src/tag.c
index 9eba4ee..d530893 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -53,6 +53,7 @@ struct near_tag {
 	uint8_t nfcid_len;
 
 	uint8_t iso15693_dsfid;
+	uint8_t iso15693_uid_len;
 	uint8_t iso15693_uid[NFC_MAX_ISO15693_UID_LEN];
 
 	size_t data_length;
@@ -168,6 +169,29 @@ static const char *type_string(struct near_tag *tag)
 	return type;
 }
 
+static const uint8_t uid_array(struct near_tag *tag, uint8_t **uid)
+{
+	if (tag->nfcid_len) {
+		DBG("NFCID: ");
+		for (int i = 0; i < tag->nfcid_len; i++)
+			DBG("%x", tag->nfcid[i]);
+
+		*uid = tag->nfcid;
+
+		return tag->nfcid_len;
+	} else if (tag->iso15693_uid_len) {
+		DBG("ISO-UID: ");
+		for (int i = 0; i < tag->iso15693_uid_len; i++)
+			DBG("%x", tag->iso15693_uid[i]);
+
+		*uid = tag->iso15693_uid;
+
+		return tag->iso15693_uid_len;
+	}
+
+	return 0;
+}
+
 static const char *protocol_string(struct near_tag *tag)
 {
 	const char *protocol;
@@ -219,6 +243,30 @@ static gboolean property_get_type(const GDBusPropertyTable *property,
 	return TRUE;
 }
 
+static gboolean property_get_uid(const GDBusPropertyTable *property,
+					DBusMessageIter *iter, void *user_data)
+{
+	struct near_tag *tag = user_data;
+	DBusMessageIter entry;
+	uint8_t *uid;
+	uint8_t len;
+
+	len = uid_array(tag, &uid);
+	if (!uid || !len)
+		return FALSE;
+
+	dbus_message_iter_open_container(iter, DBUS_TYPE_ARRAY,
+					 "{y}", &entry);
+
+	for (int i = 0; i < len; i++)
+		dbus_message_iter_append_basic(&entry, DBUS_TYPE_BYTE,
+					       (void *)&uid[i]);
+
+	dbus_message_iter_close_container(iter, &entry);
+
+	return TRUE;
+}
+
 static gboolean property_get_protocol(const GDBusPropertyTable *property,
 					DBusMessageIter *iter, void *user_data)
 {
@@ -526,6 +574,7 @@ static const GDBusPropertyTable tag_properties[] = {
 	{ "Protocol", "s", property_get_protocol },
 	{ "ReadOnly", "b", property_get_readonly },
 	{ "Adapter", "o", property_get_adapter },
+	{ "Uid", "ay", property_get_uid },
 
 	{ }
 };
@@ -671,8 +720,10 @@ static int tag_initialize(struct near_tag *tag,
 	if (nfcid_len && nfcid_len <= NFC_MAX_NFCID1_LEN) {
 		tag->nfcid_len = nfcid_len;
 		memcpy(tag->nfcid, nfcid, nfcid_len);
-	} else if (iso15693_uid_len) {
+	} else if (iso15693_uid_len &&
+		   iso15693_uid_len <= NFC_MAX_ISO15693_UID_LEN) {
 		tag->iso15693_dsfid = iso15693_dsfid;
+		tag->iso15693_uid_len = iso15693_uid_len;
 		memcpy(tag->iso15693_uid, iso15693_uid, iso15693_uid_len);
 	}
 
@@ -837,11 +888,11 @@ uint8_t *near_tag_get_iso15693_uid(uint32_t adapter_idx, uint32_t target_idx)
 	if (!tag)
 		goto fail;
 
-	iso15693_uid = g_try_malloc0(NFC_MAX_ISO15693_UID_LEN);
+	iso15693_uid = g_try_malloc0(tag->iso15693_uid_len);
 	if (!iso15693_uid)
 		goto fail;
 
-	memcpy(iso15693_uid, tag->iso15693_uid, NFC_MAX_ISO15693_UID_LEN);
+	memcpy(iso15693_uid, tag->iso15693_uid, tag->iso15693_uid_len);
 
 	return iso15693_uid;
 
-- 
2.25.1

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [linux-nfc] Re: [PATCH v2] tag: Implement readout of tag UID via DBus interface
@ 2021-03-16 18:49 Gottstein, Fabian
  0 siblings, 0 replies; 6+ messages in thread
From: Gottstein, Fabian @ 2021-03-16 18:49 UTC (permalink / raw)
  To: linux-nfc

[-- Attachment #1: Type: text/plain, Size: 6654 bytes --]

Hi Frieder,

thanks for the patch.

Could you please also consider the following situation:
In the case of a NFC Tag Type 1, the identifier is delivered via the RID command (see NFC Digital Protocol). Thus, the Tag's nfcid property is updated in a later step.
To inform the neard users, a property changed signal has to be emitted when nfcid has changed (in near_tag_set_nfcid). Also, a exists() handler for the new DBus property should be implemented.

Another thing regarding building the response message:
The following code snippet could simplify and improve the readability of the usage of the dbus message builder:

dbus_message_iter_open_container(iter, DBUS_TYPE_ARRAY, DBUS_TYPE_BYTE_AS_STRING, &entry);
dbus_message_iter_append_fixed_array(&entry, DBUS_TYPE_BYTE, &uid, len);
dbus_message_iter_close_container(iter, &entry);


Best Regards
Fabian


-----Original Message-----
From: Schrempf Frieder <frieder.schrempf@kontron.de>
Sent: Dienstag, 16. März 2021 12:22
To: Samuel Ortiz <sameo@linux.intel.com>; linux-nfc@lists.01.org
Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
Subject: [linux-nfc] [PATCH v2] tag: Implement readout of tag UID via DBus interface

Caution: This e-mail originated from outside of Philips, be careful for phishing.


From: Frieder Schrempf <frieder.schrempf@kontron.de>

NFC tags usually provide an unique identifier. Neard already checks if one of the two types of identifiers is available, reads them from tags and stores them in near_tag.nfcid or near_tag.iso15693_uid respectively.

Though currently it is not possible for any client application to get this information via the D-Bus interface as no property for the UID is implemented.

This adds a 'Uid' property to the D-Bus interface for tags, which exposes the UID of the tag as byte array. If nfcid is available this is returned as UID, otherwise if iso15693_uid is available this is returned. If no UID is available, no 'Uid' property is exposed.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
Changes in v2:
* Add whitespaces after 'for' statements
* Add more details to the commit message
---
 src/tag.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 3 deletions(-)

diff --git a/src/tag.c b/src/tag.c
index 9eba4ee..d530893 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -53,6 +53,7 @@ struct near_tag {
        uint8_t nfcid_len;

        uint8_t iso15693_dsfid;
+       uint8_t iso15693_uid_len;
        uint8_t iso15693_uid[NFC_MAX_ISO15693_UID_LEN];

        size_t data_length;
@@ -168,6 +169,29 @@ static const char *type_string(struct near_tag *tag)
        return type;
 }

+static const uint8_t uid_array(struct near_tag *tag, uint8_t **uid) {
+       if (tag->nfcid_len) {
+               DBG("NFCID: ");
+               for (int i = 0; i < tag->nfcid_len; i++)
+                       DBG("%x", tag->nfcid[i]);
+
+               *uid = tag->nfcid;
+
+               return tag->nfcid_len;
+       } else if (tag->iso15693_uid_len) {
+               DBG("ISO-UID: ");
+               for (int i = 0; i < tag->iso15693_uid_len; i++)
+                       DBG("%x", tag->iso15693_uid[i]);
+
+               *uid = tag->iso15693_uid;
+
+               return tag->iso15693_uid_len;
+       }
+
+       return 0;
+}
+
 static const char *protocol_string(struct near_tag *tag)  {
        const char *protocol;
@@ -219,6 +243,30 @@ static gboolean property_get_type(const GDBusPropertyTable *property,
        return TRUE;
 }

+static gboolean property_get_uid(const GDBusPropertyTable *property,
+                                       DBusMessageIter *iter, void
+*user_data) {
+       struct near_tag *tag = user_data;
+       DBusMessageIter entry;
+       uint8_t *uid;
+       uint8_t len;
+
+       len = uid_array(tag, &uid);
+       if (!uid || !len)
+               return FALSE;
+
+       dbus_message_iter_open_container(iter, DBUS_TYPE_ARRAY,
+                                        "{y}", &entry);
+
+       for (int i = 0; i < len; i++)
+               dbus_message_iter_append_basic(&entry, DBUS_TYPE_BYTE,
+                                              (void *)&uid[i]);
+
+       dbus_message_iter_close_container(iter, &entry);
+
+       return TRUE;
+}
+
 static gboolean property_get_protocol(const GDBusPropertyTable *property,
                                        DBusMessageIter *iter, void *user_data)  { @@ -526,6 +574,7 @@ static const GDBusPropertyTable tag_properties[] = {
        { "Protocol", "s", property_get_protocol },
        { "ReadOnly", "b", property_get_readonly },
        { "Adapter", "o", property_get_adapter },
+       { "Uid", "ay", property_get_uid },

        { }
 };
@@ -671,8 +720,10 @@ static int tag_initialize(struct near_tag *tag,
        if (nfcid_len && nfcid_len <= NFC_MAX_NFCID1_LEN) {
                tag->nfcid_len = nfcid_len;
                memcpy(tag->nfcid, nfcid, nfcid_len);
-       } else if (iso15693_uid_len) {
+       } else if (iso15693_uid_len &&
+                  iso15693_uid_len <= NFC_MAX_ISO15693_UID_LEN) {
                tag->iso15693_dsfid = iso15693_dsfid;
+               tag->iso15693_uid_len = iso15693_uid_len;
                memcpy(tag->iso15693_uid, iso15693_uid, iso15693_uid_len);
        }

@@ -837,11 +888,11 @@ uint8_t *near_tag_get_iso15693_uid(uint32_t adapter_idx, uint32_t target_idx)
        if (!tag)
                goto fail;

-       iso15693_uid = g_try_malloc0(NFC_MAX_ISO15693_UID_LEN);
+       iso15693_uid = g_try_malloc0(tag->iso15693_uid_len);
        if (!iso15693_uid)
                goto fail;

-       memcpy(iso15693_uid, tag->iso15693_uid, NFC_MAX_ISO15693_UID_LEN);
+       memcpy(iso15693_uid, tag->iso15693_uid, tag->iso15693_uid_len);

        return iso15693_uid;

--
2.25.1
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^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-08-20 15:31 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2021-03-16 11:22 [linux-nfc] [PATCH v2] tag: Implement readout of tag UID via DBus interface Schrempf Frieder
     [not found] ` <AM0P122MB011340CE87F73F55335D040C826B9@AM0P122MB0113.EURP122.PROD.OUTLOOK.COM>
2021-03-18 16:14   ` [linux-nfc] " Frieder Schrempf
2021-08-08  1:55     ` Mark Greer
2021-08-10  9:58       ` Frieder Schrempf
2021-08-20 15:31         ` Mark Greer
2021-03-16 18:49 Gottstein, Fabian

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