This patch implements bt_gatt_discover_characteristics, which can perform the
characteristic discovery procedures "Discover All Characteristics of a Service"
and "Discover Characteristics by UUID".
---
src/shared/gatt-helpers.c | 174 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 172 insertions(+), 2 deletions(-)
diff --git a/src/shared/gatt-helpers.c b/src/shared/gatt-helpers.c
index e3ca681..283e6d2 100644
--- a/src/shared/gatt-helpers.c
+++ b/src/shared/gatt-helpers.c
@@ -510,6 +510,143 @@ bool bt_gatt_discover_included_services(struct bt_att *att,
return false;
}
+struct discover_chrcs_op {
+ struct discovery_op data;
+ bool by_uuid;
+ uint16_t end;
+ struct bt_gatt_characteristic *prev_chrc;
+};
+
+static struct discover_chrcs_op *discover_chrcs_op_ref(
+ struct discover_chrcs_op *op)
+{
+ __sync_fetch_and_add(&op->data.ref_count, 1);
+
+ return op;
+}
+
+static void discover_chrcs_op_unref(void *data)
+{
+ struct discover_chrcs_op *op = data;
+
+ if (__sync_sub_and_fetch(&op->data.ref_count, 1))
+ return;
+
+ if (op->data.destroy)
+ op->data.destroy(op->data.user_data);
+
+ list_free(&op->data.results, free);
+
+ free(op);
+}
+
+static void discover_chrcs_cb(uint8_t opcode, const void *pdu,
+ uint16_t length, void *user_data)
+{
+ struct discover_chrcs_op *op = user_data;
+ bool success;
+ uint8_t att_ecode = 0;
+ struct bt_gatt_list *results = NULL;
+ size_t data_length;
+ uint16_t last_handle;
+ int i;
+
+ if (opcode == BT_ATT_OP_ERROR_RSP) {
+ success = false;
+ att_ecode = process_error(pdu, length);
+
+ if (att_ecode == BT_ATT_ERROR_ATTRIBUTE_NOT_FOUND &&
+ !list_isempty(&op->data.results))
+ goto success;
+
+ goto done;
+ }
+
+ /* PDU must contain at least the following (sans opcode):
+ * - Attr Data Length (1 octet)
+ * - Attr Data List (at least 7 octets):
+ * -- 2 octets: Attribute handle
+ * -- 1 octet: Characteristic properties
+ * -- 2 octets: Characteristic value handle
+ * -- 2 or 16 octets: characteristic UUID
+ */
+ if (opcode != BT_ATT_OP_READ_BY_TYPE_RSP || !pdu || length < 8) {
+ success = false;
+ goto done;
+ }
+
+ data_length = ((uint8_t *) pdu)[0];
+
+ if (((length - 1) % data_length) ||
+ (data_length != 7 && data_length != 21)) {
+ success = false;
+ goto done;
+ }
+
+ for (i = 1; i < length; i += data_length) {
+ struct bt_gatt_characteristic *chrc;
+ bt_uuid_t uuid;
+
+ chrc = new0(struct bt_gatt_characteristic, 1);
+ if (!chrc) {
+ success = false;
+ goto done;
+ }
+
+ last_handle = get_le16(pdu + i);
+ chrc->start = last_handle;
+ chrc->properties = ((uint8_t *) pdu)[i + 2];
+ chrc->value = get_le16(pdu + i + 3);
+ convert_uuid_le(pdu + i + 5, data_length - 5, chrc->uuid);
+
+ uuid.type = BT_UUID128;
+ memcpy(&uuid.value.u128, chrc->uuid, 16);
+
+ if (op->prev_chrc)
+ op->prev_chrc->end = chrc->start - 1;
+
+ op->prev_chrc = chrc;
+
+ if (!op->by_uuid || !bt_uuid_cmp(&uuid, &op->data.uuid)) {
+ if (!list_add(&op->data.results, chrc)) {
+ success = false;
+ goto done;
+ }
+ }
+ }
+
+ if (last_handle != op->end) {
+ uint8_t pdu[6];
+
+ put_le16(last_handle + 1, pdu);
+ put_le16(op->end, pdu + 2);
+ put_le16(GATT_CHARAC_UUID, pdu + 4);
+
+ if (bt_att_send(op->data.att, BT_ATT_OP_READ_BY_TYPE_REQ,
+ pdu, sizeof(pdu),
+ discover_chrcs_cb,
+ discover_chrcs_op_ref(op),
+ discover_chrcs_op_unref))
+ return;
+
+ discover_chrcs_op_unref(op);
+ success = false;
+ goto done;
+ }
+
+success:
+ results = op->data.results.head;
+ success = true;
+
+ if (op->prev_chrc)
+ op->prev_chrc->end = op->end - 1;
+
+done:
+ if (op->data.callback)
+ op->data.callback(success, att_ecode, results,
+ op->data.user_data);
+}
+
bool bt_gatt_discover_characteristics(struct bt_att *att,
uint16_t start, uint16_t end,
bt_uuid_t *uuid,
@@ -517,8 +654,41 @@ bool bt_gatt_discover_characteristics(struct bt_att *att,
void *user_data,
bt_gatt_destroy_func_t destroy)
{
- /* TODO */
- return false;
+ struct discover_chrcs_op *op;
+ uint8_t pdu[6];
+
+ if (!att)
+ return false;
+
+ op = new0(struct discover_chrcs_op, 1);
+ if (!op)
+ return false;
+
+ if (uuid) {
+ op->by_uuid = true;
+ op->data.uuid = *uuid;
+ }
+
+ op->data.att = att;
+ op->data.callback = callback;
+ op->data.user_data = user_data;
+ op->data.destroy = destroy;
+ op->end = end;
+
+ put_le16(start, pdu);
+ put_le16(end, pdu + 2);
+ put_le16(GATT_CHARAC_UUID, pdu + 4);
+
+ if (!bt_att_send(att, BT_ATT_OP_READ_BY_TYPE_REQ,
+ pdu, sizeof(pdu),
+ discover_chrcs_cb,
+ discover_chrcs_op_ref(op),
+ discover_chrcs_op_unref)) {
+ free(op);
+ return false;
+ }
+
+ return true;
}
bool bt_gatt_discover_descriptors(struct bt_att *att,
--
2.0.0.526.g5318336
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