Low level Bluetooth support
Currently contains only GATT server implmenetation for ESP32.
Configuration section
bt-common library adds a bt configuration section with the following
settings:
"bt": {
"enable": true, // Enabled by default. Disabled on first reboot with WiFi on
"dev_name": "", // Device name. If empty, value equals to device.id
"adv_enable": true, // Advertise our Bluetooth services
"keep_enabled": true, // Keep enabled after successful boot with WiFi on
"scan_rsp_data_hex": "", // Custom scan response data, as hex string (e.g. `48656c6c6f` for `Hello`)
"allow_pairing": true, // Allow pairingbonding with other devices
"max_paired_devices": 10, // Allow pairing with up to this many devices; -1 - no limit
"gatts": {
"min_sec_level": 0, // Minimum security level for all attributes of all services.
// 0 - no auth required, 1 - encryption reqd, 2 - encryption + MITM reqd
"require_pairing": false // Require taht device is paired before accessing services
}
}
Security
Default settings allow for unrestricted access: anyone can pair with a device and access the services.
A better idea is to set bt.gatts.require_pairing to true, bt.allow_pairing to false and only enable it for a limited time via mgos_bt_gap_set_pairing_enable when user performs some action, e.g. presses a button.
Raising bt.gatts.min_sec_level to at least 1 is also advisable.
Note: At present, level 2 (MITM protection) is not usable as it requires device to have at least output capability during pairing, and there's no API for displaying the pairing code yet.