facedancer.backends.libusbhost module

Host support for accessing libusb with a Facedancer-like syntax.

class facedancer.backends.libusbhost.LibUSBHostApp(verbose=0, quirks=[], index=0, **kwargs)

Bases: FacedancerUSBHost

Class that represents a libusb-based USB host.

__init__(verbose=0, quirks=[], index=0, **kwargs)

Creates a new libusb backend for communicating with a target device.

app_name = 'LibUSB Host'

classmethod appropriate_for_environment(backend_name)

Determines if the current environment seems appropriate for using the libusb backend.

bus_reset(delay=0)

Issues a “bus reset”, requesting that the downstream device reset itself.

Parameters:

delay – The amount of time, in seconds, to wait before or after the reset request. To be compliant, this should be omitted, or set to 0.1s.

connect(device_speed=None)

Sets up our host to talk to the device, including turning on VBUS.

control_request_in(request_type, recipient, request, value=0, index=0, length=0)

Performs an IN control request.

Parameters:

• request_type – Determines if this is a standard, class, or vendor request. Accepts a REQUEST_TYPE_* constant.

• recipient – Determines the context in which this command is interpreted. Accepts a REQUEST_RECIPIENT_* constant.

• request – The request number to be performed.

• value, index – The standard USB request arguments, to be included in the setup packet. Their meaning varies depending on the request.

• length – The maximum length of data expected in response, or 0 if we don’t expect any data back.

control_request_out(request_type, recipient, request, value=0, index=0, data=[])

Performs an OUT control request.

Parameters:

• request_type – Determines if this is a standard, class, or vendor request. Accepts a REQUEST_TYPE_* constant.

• recipient – Determines the context in which this command is interpreted. Accepts a REQUEST_RECIPIENT_* constant.

• request – The request number to be performed.

• value, index – The standard USB request arguments, to be included in the setup packet. Their meaning varies depending on the request.

• data – The data to be transmitted with this control request.

current_device_speed(as_string=False)

Returns the speed of the connected device

Parameters:

as_string – If true, returns the speed as a string for printing; otherwise returns a DEVICE_SPEED_* constant.

current_line_state(as_string=False)

Returns the current state of the USB differential pair

as_stringIf true, returns the speed as a string for printing; otherwise

returns a LINE_STATE_* constant.

device_is_connected()

Returns true iff a given device is connected.

initialize_control_endpoint(device_address=None, device_speed=None, max_packet_size=None)

Set up the device’s control endpoint, so we can use it for e.g. enumeration.

port_is_enabled()

Returns true iff a given device is connected.

port_is_powered()

Returns true iff a given device is connected.

read_from_endpoint(endpoint_number, expected_read_size=64, data_packet_pid=0)

Sends a block of data on the provided endpoints.

Parameters:

• endpoint_number – The endpoint number on which to send.

• expected_read_size – The expected amount of data to be read.

• data_packet_pid – The data packet PID to use (1 or 0). Ignored if the endpoint is set to automatically alternate data PIDs.

raises an IOError on a communications error or stall

send_on_endpoint(endpoint_number, data, is_setup=False, blocking=True, data_packet_pid=0)

Sends a block of data on the provided endpoints.

Parameters:

• endpoint_number – The endpoint number on which to send.

• data – The data to be transmitted.

• is_setup – True iff this transfer should begin with a SETUP token.

• blocking – True iff this transaction should wait for the transaction to complete.

• data_packet_pid – The data packet PID to use (1 or 0). Ignored if the endpoint is set to automatically alternate data PIDs.

raises an IOError on a communications error or stall

set_up_endpoint(endpoint_address_or_object, endpoint_type=None, max_packet_size=None, device_address=None, endpoint_speed=None, handle_data_toggle=None, is_control_endpoint=None)

Sets up an endpoint for use. Can be used to initialize an endpoint or to update its parameters. Two forms exist:

Parameters:

endpoint_object – a USBEndpoint object with the parameters to be populated

or

Parameters:

• endpoint_address – the address of the endpoint to be setup; including the direction bit

• endpoint_type – one of the ENDPOINT_TYPE constants that specifies the transfer mode on the endpoint_address

• max_packet_size – the maximum packet size to be communicated on the given endpoint

• device_address – the address of the device to be communicated with; if not provided, the last address will be used

• endpoint_speed – the speed of the packets to be communicated on the endpoint; should be a DEVICE_SPEED_* constant; if not provided, the last device’s speed will be used.

• handle_data_toggle – true iff the hardware should automatically handle selection of data packet PIDs

• is_control_endpoint – true iff the given packet is a for a control endpoint