def handle_socket(self) -> None:
"""Retrieves the next, waiting DHCP packet, parses it and calls the
handler of the associated request.
"""
try:
data, source_address = self._socket.recvfrom(2048)
if len(data) == 0:
self._log.warning("unexpectedly received EOF!")
return
packet = DhcpPacket()
packet.source_address = source_address
packet.DecodePacket(data)
if (not packet.IsDhcpPacket()) or (
not packet.IsOption("dhcp_message_type")
):
self._log.debug("Ignoring invalid packet")
return
dhcp_type = packet.GetOption("dhcp_message_type")[0]
if dhcp_type not in self._DHCP_TYPE_HANDLERS:
self._log.debug("Ignoring packet of unexpected DHCP type %d", dhcp_type)
return
xid = int.from_bytes(packet.GetOption('xid'), "big")
if xid not in self._requests:
self._log.debug("Ignoring answer with xid %r", xid)
return
request = self._requests[xid]
clb_name = self._DHCP_TYPE_HANDLERS[dhcp_type]
if not hasattr(request, clb_name):
self._log.error("request has no callback '%s'", clb_name)
return
clb = getattr(request, clb_name)
clb(packet)
except Exception:
self._log.exception('handling DHCP packet failed')
def handle_dhcp_ack(self, packet: DhcpPacket) -> None:
"""Called by the requestor as soon as a DHCP ACK packet is received for
our XID.
In case the packet matches what we currently expect, the packet is
parsed and the success handler called.
The request instance (self) is removed from the requestor and will
therefore be destroyed soon.
"""
if self._state != self.AR_REQUEST:
return
self._log.debug("Received ACK")
if not self._valid_source_address(packet):
return
if self._timeout_obj:
self._timeout_mgr.del_timeout_object(self._timeout_obj)
self._requestor.del_request(self)
result = {} # type: Dict[str, Any]
result['domain'] = packet.GetOption('domain_name').decode("ascii")
translate_ips = {
'yiaddr': 'ip_address',
'subnet_mask': 'subnet_mask',
'router': 'gateway',
}
for opt_name in translate_ips:
if not packet.IsOption(opt_name):
continue
val = packet.GetOption(opt_name)
if len(val) == 4:
result[translate_ips[opt_name]] = str(IPv4Address(val))
dns = [] # type: List[str]
result['dns'] = dns
dns_list = packet.GetOption('domain_name_server')
while len(dns_list) >= 4:
dns.append(str(IPv4Address(dns_list[:4])))
dns_list = dns_list[4:]
if packet.IsOption('classless_static_route'):
static_routes = parse_classless_static_routes(
list(packet.GetOption('classless_static_route'))
)
if static_routes is not None:
if 'gateway' in result:
# We MUST ignore a regular default route if static routes
# are sent.
del result['gateway']
# Find and filter out default route (if any). And set it as
# the new gateway parameter.
result['static_routes'] = []
for network, netmask, gateway in static_routes:
if network == '0.0.0.0' and netmask == '0.0.0.0':
result['gateway'] = gateway
else:
result['static_routes'].append((network, netmask, gateway))
del static_routes
# Calculate lease timeouts (with RFC T1/T2 if not found in packet)
lease_delta = int.from_bytes(packet.GetOption('ip_address_lease_time'), "big")
result['lease_timeout'] = self._start_time + lease_delta
if packet.IsOption('renewal_time_value'):
renewal_delta = int.from_bytes(
packet.GetOption('renewal_time_value'), "big"
)
else:
renewal_delta = int(lease_delta * 0.5) + random.randint(-5, 5)
result['renewal_timeout'] = self._start_time + renewal_delta
if packet.IsOption('rebinding_time_value'):
rebinding_delta = int.from_bytes(
packet.GetOption('rebinding_time_value'), "big"
)
else:
rebinding_delta = int(lease_delta * 0.875) + random.randint(-5, 5)
result['rebinding_timeout'] = self._start_time + rebinding_delta
self._success_handler(result)
