From: Andre Guedes <andre.guedes@xxxxxxxxxxxxx>
This patch adds btd_gatt_add_char() helper. It creates and adds the
Characteristic declaration, and Characteristic value attributes to the
local attribute database.
---
src/gatt.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/gatt.h | 12 +++++++++
2 files changed, 98 insertions(+)
diff --git a/src/gatt.c b/src/gatt.c
index eed4fae..669c716 100644
--- a/src/gatt.c
+++ b/src/gatt.c
@@ -40,6 +40,9 @@
static const bt_uuid_t primary_uuid = { .type = BT_UUID16,
.value.u16 = GATT_PRIM_SVC_UUID };
+static const bt_uuid_t chr_uuid = { .type = BT_UUID16,
+ .value.u16 = GATT_CHARAC_UUID };
+
struct btd_attribute {
uint16_t handle;
bt_uuid_t type;
@@ -50,6 +53,11 @@ struct btd_attribute {
static GList *local_attribute_db;
static uint16_t next_handle = 0x0001;
+static inline void put_le16(uint16_t val, void *dst)
+{
+ put_unaligned(cpu_to_le16(val), (uint16_t *) dst);
+}
+
static inline void put_uuid(const bt_uuid_t *src, void *dst)
{
if (src->type == BT_UUID16)
@@ -120,6 +128,84 @@ struct btd_attribute *btd_gatt_add_service(const bt_uuid_t *uuid)
return attr;
}
+struct btd_attribute *btd_gatt_add_char(const bt_uuid_t *uuid,
+ uint8_t properties)
+{
+ struct btd_attribute *char_decl, *char_value = NULL;
+
+ /* Attribute value length */
+ uint16_t len = 1 + 2 + bt_uuid_len(uuid);
+ uint8_t value[len];
+
+ /*
+ * Characteristic DECLARATION
+ *
+ * TYPE ATTRIBUTE VALUE
+ * +-------+---------------------------------+
+ * |0x2803 | 0xXX 0xYYYY 0xZZZZ... |
+ * | (1) | (2) (3) (4) |
+ * +------+----------------------------------+
+ * (1) - 2 octets: Characteristic declaration UUID
+ * (2) - 1 octet : Properties
+ * (3) - 2 octets: Handle of the characteristic Value
+ * (4) - 2 or 16 octets: Characteristic UUID
+ */
+
+ value[0] = properties;
+
+ /*
+ * Since we don't know yet the characteristic value attribute
+ * handle, we skip and set it later.
+ */
+
+ put_uuid(uuid, &value[3]);
+
+ char_decl = new_const_attribute(&chr_uuid, value, len);
+ if (local_database_add(next_handle, char_decl) < 0)
+ goto fail;
+
+ next_handle = next_handle + 1;
+
+ /*
+ * Characteristic VALUE
+ *
+ * TYPE ATTRIBUTE VALUE
+ * +----------+---------------------------------+
+ * |0xZZZZ... | 0x... |
+ * | (1) | (2) |
+ * +----------+---------------------------------+
+ * (1) - 2 or 16 octets: Characteristic UUID
+ * (2) - N octets: Value is read dynamically from the service
+ * implementation (external entity).
+ */
+
+ char_value = new0(struct btd_attribute, 1);
+ char_value->type = *uuid;
+
+ /* TODO: Read & Write callbacks */
+
+ if (local_database_add(next_handle, char_value) < 0)
+ goto fail;
+
+ next_handle = next_handle + 1;
+
+ /*
+ * Update characteristic value handle in characteristic declaration
+ * attribute. For local attributes, we can assume that the handle
+ * representing the characteristic value will get the next available
+ * handle. However, for remote attribute this assumption is not valid.
+ */
+ put_le16(char_value->handle, &char_decl->value[1]);
+
+ return char_value;
+
+fail:
+ free(char_decl);
+ free(char_value);
+
+ return NULL;
+}
+
void gatt_init(void)
{
DBG("Starting GATT server");
diff --git a/src/gatt.h b/src/gatt.h
index 8dd1312..d7acc5b 100644
--- a/src/gatt.h
+++ b/src/gatt.h
@@ -34,3 +34,15 @@ void gatt_cleanup(void);
* NULL is returned.
*/
struct btd_attribute *btd_gatt_add_service(const bt_uuid_t *uuid);
+
+/*
+ * btd_gatt_add_char - Add a characteristic (declaration and value attributes)
+ * to local attribute database.
+ * @uuid: Characteristic UUID (16-bits or 128-bits).
+ * @properties: Characteristic properties. See Core SPEC 4.1 page 2183.
+ *
+ * Returns a reference to characteristic value attribute. In case of error,
+ * NULL is returned.
+ */
+struct btd_attribute *btd_gatt_add_char(const bt_uuid_t *uuid,
+ uint8_t properties);
--
1.8.3.1
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