103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
from adafruit_ble import BLERadio
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from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
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from adafruit_ble.services.standard.hid import HIDService
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from kmk.hid import AbstractHID
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BLE_APPEARANCE_HID_KEYBOARD = 961
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# Hardcoded in CPy
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MAX_CONNECTIONS = 2
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class BLEHID(AbstractHID):
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def post_init(self, ble_name='KMK Keyboard', **kwargs):
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self.conn_id = -1
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self.ble = BLERadio()
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self.ble.name = ble_name
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self.hid = HIDService()
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self.hid.protocol_mode = 0 # Boot protocol
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# Security-wise this is not right. While you're away someone turns
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# on your keyboard and they can pair with it nice and clean and then
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# listen to keystrokes.
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# On the other hand we don't have LESC so it's like shouting your
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# keystrokes in the air
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if not self.ble.connected or not self.hid.devices:
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self.start_advertising()
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self.conn_id = 0
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@property
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def devices(self):
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'''Search through the provided list of devices to find the ones with the
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send_report attribute.'''
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if not self.ble.connected:
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return []
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result = []
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# Security issue:
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# This introduces a race condition. Let's say you have 2 active
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# connections: Alice and Bob - Alice is connection 1 and Bob 2.
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# Now Chuck who has already paired with the device in the past
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# (this assumption is needed only in the case of LESC)
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# wants to gather the keystrokes you send to Alice. You have
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# selected right now to talk to Alice (1) and you're typing a secret.
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# If Chuck kicks Alice off and is quick enough to connect to you,
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# which means quicker than the running interval of this function,
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# he'll be earlier in the `self.hid.devices` so will take over the
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# selected 1 position in the resulted array.
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# If no LESC is in place, Chuck can sniff the keystrokes anyway
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for device in self.hid.devices:
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if hasattr(device, 'send_report'):
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result.append(device)
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return result
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def _check_connection(self):
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devices = self.devices
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if not devices:
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return False
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if self.conn_id >= len(devices):
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self.conn_id = len(devices) - 1
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if self.conn_id < 0:
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return False
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if not devices[self.conn_id]:
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return False
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return True
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def hid_send(self, evt):
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if not self._check_connection():
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return
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device = self.devices[self.conn_id]
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while len(evt) < len(device._characteristic.value) + 1:
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evt.append(0)
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return device.send_report(evt[1:])
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def clear_bonds(self):
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import _bleio
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_bleio.adapter.erase_bonding()
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def next_connection(self):
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self.conn_id = (self.conn_id + 1) % len(self.devices)
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def previous_connection(self):
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self.conn_id = (self.conn_id - 1) % len(self.devices)
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def start_advertising(self):
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advertisement = ProvideServicesAdvertisement(self.hid)
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advertisement.appearance = BLE_APPEARANCE_HID_KEYBOARD
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self.ble.start_advertising(advertisement)
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def stop_advertising(self):
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self.ble.stop_advertising()
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