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extmod/btstack: Fix MTU handling. 

There was no event handler for central-initiated MTU exchange.

Fix truncation of notify/indicate to match NimBLE.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared 2023-03-09 23:50:20 +11:00
parent a652695153
commit a2df439dd3
1 changed files with 14 additions and 3 deletions
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17
extmod/btstack/modbluetooth_btstack.c
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@ -172,12 +172,14 @@ STATIC void btstack_packet_handler_att_server(uint8_t packet_type, uint16_t chan
uint8_t status = att_event_handle_value_indication_complete_get_status(packet);
mp_bluetooth_gatts_on_indicate_complete(conn_handle, value_handle, status);
} else if (event_type == ATT_EVENT_MTU_EXCHANGE_COMPLETE) {
DEBUG_printf(" --> att mtu exchange complete\n");
// This is triggered in peripheral mode, when exchange initiated by us or remote.
uint16_t conn_handle = att_event_mtu_exchange_complete_get_handle(packet);
uint16_t mtu = att_event_mtu_exchange_complete_get_MTU(packet);
mp_bluetooth_gatts_on_mtu_exchanged(conn_handle, mtu);
} else if (event_type == HCI_EVENT_LE_META || event_type == HCI_EVENT_DISCONNECTION_COMPLETE) {
// Ignore, duplicated by att_server.c.
DEBUG_printf(" --> hci att server event type: le_meta/disconnection (0x%02x)\n", event_type);
} else {
DEBUG_printf(" --> hci att server event type: unknown (0x%02x)\n", event_type);
}
@ -330,7 +332,8 @@ STATIC void btstack_packet_handler_generic(uint8_t packet_type, uint16_t channel
#endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
#if MICROPY_PY_BLUETOOTH_ENABLE_GATT_CLIENT
} else if (event_type == GATT_EVENT_MTU) {
// This is triggered in client mode.
// This is triggered in central mode.
DEBUG_printf(" --> gatt event mtu\n");
uint16_t conn_handle = gatt_event_mtu_get_handle(packet);
uint16_t mtu = gatt_event_mtu_get_MTU(packet);
mp_bluetooth_gatts_on_mtu_exchanged(conn_handle, mtu);
@ -1108,6 +1111,14 @@ int mp_bluetooth_gatts_notify_indicate(uint16_t conn_handle, uint16_t value_hand
mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_btstack_root_pointers)->gatts_db, value_handle, &value, &value_len);
}
// Even if a lower MTU is negotiated, btstack allows sending a larger
// notification/indication. Truncate at the MTU-3 (to match NimBLE).
uint16_t current_mtu = att_server_get_mtu(conn_handle);
if (current_mtu) {
current_mtu -= 3;
value_len = MIN(value_len, current_mtu);
}
int err = ERROR_CODE_UNKNOWN_HCI_COMMAND;
// Attempt to send immediately. If it succeeds, btstack will copy the buffer.
@ -1443,9 +1454,9 @@ int mp_bluetooth_gattc_write(uint16_t conn_handle, uint16_t value_handle, const
}
int mp_bluetooth_gattc_exchange_mtu(uint16_t conn_handle) {
DEBUG_printf("mp_bluetooth_exchange_mtu: conn_handle=%d mtu=%d\n", conn_handle, l2cap_max_le_mtu());
DEBUG_printf("mp_bluetooth_gattc_exchange_mtu: conn_handle=%d mtu=%d\n", conn_handle, l2cap_max_le_mtu());
gatt_client_send_mtu_negotiation(&btstack_packet_handler_att_server, conn_handle);
gatt_client_send_mtu_negotiation(&btstack_packet_handler_generic, conn_handle);
return 0;
}