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Convert perform_pair_setup_part* to be state machines #165

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Merged
jlusiardi merged 2 commits into from
Sep 6, 2019
Merged

Convert perform_pair_setup_part* to be state machines #165

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78bf27d
Convert perform_pair_setup_part* to be state machines
Jc2k Aug 25, 2019
ad8ea00
Remove use of create_ble_pair_setup_write
Jc2k Aug 25, 2019
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18 changes: 4 additions & 14 deletions homekit/controller/ble_impl/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -471,7 +471,7 @@ def __init__(self, pairing_data, adapter):
# TODO Have exception here
sys.exit(-1)

write_fun = create_ble_pair_verify_write(pair_verify_char, pair_verify_char_info['iid'])
write_fun = create_ble_pair_setup_write(pair_verify_char, pair_verify_char_info['iid'])
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@jlusiardi jlusiardi Aug 26, 2019

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so we do not have separate functions for create_ble_pair_verify_write and create_ble_pair_setup_write anymore, can we find a better name? perhaps create_characteristic_write_function?

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@Jc2k Jc2k Aug 26, 2019

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I think we can actually factor out the need for the create_ part entirely really, but i didn't want to over complicate this PR.

Now that we aren't passing it into the state machine we don't need to capture the scope. So it could just be a generic write helper like (pseudo-code, won't work as is):

def write_hap_param_value(char, iid, request, expected):
    pass

...

def setup_session():
    char, iid = find_char_by_type(PAIR_VERIFY)
    state_machine = ...
    while True:
        response = write_hap_param_value(char, iid, request, expected)
        request, expected = state_machine.send(response)

state_machine = get_session_keys(self.pairing_data)

request, expected = state_machine.send(None)
Expand Down Expand Up @@ -613,10 +613,11 @@ def find_characteristic_by_uuid(device, service_uuid, char_uuid):
def create_ble_pair_setup_write(characteristic, characteristic_id):
def write(request, expected):
# TODO document me
logger.debug('entering write function %s', TLV.to_string(TLV.decode_bytes(request)))
body = TLV.encode_list(request)
logger.debug('entering write function %s', TLV.to_string(TLV.decode_bytes(body)))
request_tlv = TLV.encode_list([
(TLV.kTLVHAPParamParamReturnResponse, bytearray(b'\x01')),
(TLV.kTLVHAPParamValue, request)
(TLV.kTLVHAPParamValue, body)
])
transaction_id = random.randrange(0, 255)
data = bytearray([0x00, HapBleOpCodes.CHAR_WRITE, transaction_id])
Expand Down Expand Up @@ -654,17 +655,6 @@ def write(request, expected):
return write


def create_ble_pair_verify_write(characteristic, characteristic_id):
# This is a temporary wrapper until the pairing functions are also migrated to
# the new state machine approach
pair_setup_write = create_ble_pair_setup_write(characteristic, characteristic_id)

def write(request, expected):
return pair_setup_write(TLV.encode_list(request), expected)

return write


class ResolvingManager(DeviceManager):
"""
DeviceManager implementation that stops running after a given device was discovered.
Expand Down
45 changes: 41 additions & 4 deletions homekit/controller/controller.py
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Original file line number Diff line number Diff line change
Expand Up @@ -380,17 +380,36 @@ def start_pairing(self, alias, accessory_id):

try:
write_fun = create_ip_pair_setup_write(conn)
salt, pub_key = perform_pair_setup_part1(write_fun)

state_machine = perform_pair_setup_part1()
request, expected = state_machine.send(None)
while True:
try:
response = write_fun(request, expected)
request, expected = state_machine.send(response)
except StopIteration as result:
salt, pub_key = result.value
break

except Exception:
conn.close()
raise

def finish_pairing(pin):
Controller.check_pin_format(pin)
try:
pairing = perform_pair_setup_part2(pin, str(uuid.uuid4()), write_fun, salt, pub_key)
state_machine = perform_pair_setup_part2(pin, str(uuid.uuid4()), salt, pub_key)
request, expected = state_machine.send(None)
while True:
try:
response = write_fun(request, expected)
request, expected = state_machine.send(response)
except StopIteration as result:
pairing = result.value
break
finally:
conn.close()

pairing['AccessoryIP'] = connection_data['ip']
pairing['AccessoryPort'] = connection_data['port']
pairing['Connection'] = 'IP'
Expand Down Expand Up @@ -456,11 +475,29 @@ def start_pairing_ble(self, alias, accessory_mac, adapter='hci0'):
logging.debug('setup char: %s %s', pair_setup_char, pair_setup_char.service.device)

write_fun = create_ble_pair_setup_write(pair_setup_char, pair_setup_char_id)
salt, pub_key = perform_pair_setup_part1(write_fun)

state_machine = perform_pair_setup_part1()
request, expected = state_machine.send(None)
while True:
try:
response = write_fun(request, expected)
request, expected = state_machine.send(response)
except StopIteration as result:
salt, pub_key = result.value
break

def finish_pairing(pin):
Controller.check_pin_format(pin)
pairing = perform_pair_setup_part2(pin, str(uuid.uuid4()), write_fun, salt, pub_key)

state_machine = perform_pair_setup_part2(pin, str(uuid.uuid4()), salt, pub_key)
request, expected = state_machine.send(None)
while True:
try:
response = write_fun(request, expected)
request, expected = state_machine.send(response)
except StopIteration as result:
pairing = result.value
break

pairing['AccessoryMAC'] = accessory_mac
pairing['Connection'] = 'BLE'
Expand Down
31 changes: 14 additions & 17 deletions homekit/protocol/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,11 +57,12 @@ def error_handler(error, stage):

def create_ip_pair_setup_write(connection):
def write_http(request, expected):
logging.debug('write message: %s', TLV.to_string(TLV.decode_bytes(request)))
body = TLV.encode_list(request)
logging.debug('write message: %s', TLV.to_string(TLV.decode_bytes(body)))
connection.putrequest('POST', '/pair-setup', skip_accept_encoding=True)
connection.putheader('Content-Type', 'application/pairing+tlv8')
connection.putheader('Content-Length', len(request))
connection.endheaders(request)
connection.putheader('Content-Length', len(body))
connection.endheaders(body)
resp = connection.getresponse()
response_tlv = TLV.decode_bytes(resp.read(), expected)
logging.debug('response: %s', TLV.to_string(response_tlv))
Expand All @@ -86,12 +87,10 @@ def write_http(request, expected):
return write_http


def perform_pair_setup_part1(write_fun):
def perform_pair_setup_part1():
"""
Performs a pair setup operation as described in chapter 4.7 page 39 ff.

:param write_fun: a function that takes a bytes representation of a TLV, the expected keys as list and returns
decoded TLV as list
:return: a tuple of salt and server's public key
:raises UnavailableError: if the device is already paired
:raises MaxTriesError: if the device received more than 100 unsuccessful pairing attempts
Expand All @@ -105,13 +104,13 @@ def perform_pair_setup_part1(write_fun):
# Step #1 ios --> accessory (send SRP start Request) (see page 39)
#
logging.debug('#1 ios -> accessory: send SRP start request')
request_tlv = TLV.encode_list([
request_tlv = [
(TLV.kTLVType_State, TLV.M1),
(TLV.kTLVType_Method, TLV.PairSetup)
])
]

step2_expectations = [TLV.kTLVType_State, TLV.kTLVType_Error, TLV.kTLVType_PublicKey, TLV.kTLVType_Salt]
response_tlv = write_fun(request_tlv, step2_expectations)
response_tlv = yield (request_tlv, step2_expectations)

#
# Step #3 ios --> accessory (send SRP verify request) (see page 41)
Expand All @@ -129,17 +128,16 @@ def perform_pair_setup_part1(write_fun):

assert response_tlv[1][0] == TLV.kTLVType_PublicKey, 'perform_pair_setup: Not a public key'
assert response_tlv[2][0] == TLV.kTLVType_Salt, 'perform_pair_setup: Not a salt'

return response_tlv[2][1], response_tlv[1][1]


def perform_pair_setup_part2(pin, ios_pairing_id, write_fun, salt, server_public_key):
def perform_pair_setup_part2(pin, ios_pairing_id, salt, server_public_key):
"""
Performs a pair setup operation as described in chapter 4.7 page 39 ff.

:param pin: the setup code from the accessory
:param ios_pairing_id: the id of the simulated ios device
:param write_fun: a function that takes a bytes representation of a TLV, the expected keys as list and returns
decoded TLV as list
:return: a dict with the ios device's part of the pairing information
:raises UnavailableError: if the device is already paired
:raises MaxTriesError: if the device received more than 100 unsuccessful pairing attempts
Expand All @@ -155,14 +153,14 @@ def perform_pair_setup_part2(pin, ios_pairing_id, write_fun, salt, server_public
client_pub_key = srp_client.get_public_key()
client_proof = srp_client.get_proof()

response_tlv = TLV.encode_list([
response_tlv = [
(TLV.kTLVType_State, TLV.M3),
(TLV.kTLVType_PublicKey, SrpClient.to_byte_array(client_pub_key)),
(TLV.kTLVType_Proof, SrpClient.to_byte_array(client_proof)),
])
]

step4_expectations = [TLV.kTLVType_State, TLV.kTLVType_Error, TLV.kTLVType_Proof]
response_tlv = write_fun(response_tlv, step4_expectations)
response_tlv = yield (response_tlv, step4_expectations)

#
# Step #5 ios --> accessory (Exchange Request) (see page 43)
Expand Down Expand Up @@ -220,10 +218,9 @@ def perform_pair_setup_part2(pin, ios_pairing_id, write_fun, salt, server_public
(TLV.kTLVType_State, TLV.M5),
(TLV.kTLVType_EncryptedData, tmp)
]
body = TLV.encode_list(response_tlv)

step6_expectations = [TLV.kTLVType_State, TLV.kTLVType_Error, TLV.kTLVType_EncryptedData]
response_tlv = write_fun(body, step6_expectations)
response_tlv = yield (response_tlv, step6_expectations)

#
# Step #7 ios (Verification) (page 47)
Expand Down