This patch implements the helper function bt_gatt_exchange_mtu, which performs
an ATT "Exchange MTU" request and resizes the internal buffer based on the
result.
---
src/shared/gatt-helpers.c | 87 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 85 insertions(+), 2 deletions(-)
diff --git a/src/shared/gatt-helpers.c b/src/shared/gatt-helpers.c
index 3d85868..9cf05cf 100644
--- a/src/shared/gatt-helpers.c
+++ b/src/shared/gatt-helpers.c
@@ -30,14 +30,97 @@
#include "src/shared/att.h"
#include "lib/uuid.h"
#include "src/shared/gatt-helpers.h"
+#include "src/shared/util.h"
+
+#ifndef MIN
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+struct mtu_op {
+ struct bt_att *att;
+ uint16_t client_rx_mtu;
+ bt_gatt_result_callback_t callback;
+ void *user_data;
+ bt_gatt_destroy_func_t destroy;
+};
+
+static void destroy_mtu_op(void *user_data)
+{
+ struct mtu_op *op = user_data;
+
+ if (op->destroy)
+ op->destroy(op->user_data);
+
+ free(op);
+}
+
+static uint16_t process_error(const void *pdu, uint16_t length)
+{
+ if (!pdu || length != 4)
+ return BT_GATT_ERROR_INVALID_RSP;
+
+ return (uint16_t)((uint8_t *) pdu)[3];
+}
+
+static void mtu_cb(uint8_t opcode, const void *pdu, uint16_t length,
+ void *user_data)
+{
+ struct mtu_op *op = user_data;
+ uint16_t result = 0;
+ uint16_t server_rx_mtu;
+
+ if (opcode == BT_ATT_OP_ERROR_RSP) {
+ result = process_error(pdu, length);
+ goto done;
+ }
+
+ if (opcode != BT_ATT_OP_MTU_RSP || !pdu || length != 2) {
+ result = BT_GATT_ERROR_INVALID_RSP;
+ goto done;
+ }
+
+ server_rx_mtu = get_le16(pdu);
+ bt_att_set_mtu(op->att, MIN(op->client_rx_mtu, server_rx_mtu));
+
+done:
+ if (op->callback)
+ op->callback(result, op->user_data);
+}
bool bt_gatt_exchange_mtu(struct bt_att *att, uint16_t client_rx_mtu,
bt_gatt_result_callback_t callback,
void *user_data,
bt_gatt_destroy_func_t destroy)
{
- /* TODO */
- return false;
+ struct mtu_op *op;
+ uint8_t pdu[2];
+
+ if (!att)
+ return false;
+
+ if (!client_rx_mtu)
+ return false;
+
+ op = new0(struct mtu_op, 1);
+ if (!op)
+ return false;
+
+ op->att = att;
+ op->client_rx_mtu = client_rx_mtu;
+ op->callback = callback;
+ op->user_data = user_data;
+ op->destroy = destroy;
+
+ put_le16(client_rx_mtu, pdu);
+
+ if (!bt_att_send(att, BT_ATT_OP_MTU_REQ, pdu, sizeof(pdu),
+ mtu_cb, op,
+ destroy_mtu_op)) {
+ free(op);
+ return false;
+ }
+
+ return true;
}
bool bt_gatt_discover_primary_services(struct bt_att *att,
--
2.0.0.526.g5318336
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