def _change_root(self, port_in, bpdu_in):
"""
This function updates the root information for the incoming BPDU on the port_in
Since this is used a few times, this function was created to minimize redundancy
:param port_in: the port the bpdu was received on
:param bpdu_in: the bpdu that will update this bridge's root information
:return: Void
"""
changed_root = self.bridge_BPDU.root != bpdu_in.root
changed_root_id = self.rootPort_ID != port_in.port_id
self.bridge_BPDU = BPDU(self.id, 'ffff', 1, bpdu_in.root, bpdu_in.cost + 1)
if changed_root:
self._print_new_root()
# set bridge's root port to this port
self.rootPort_ID = port_in.port_id
port_in.designated = False
if changed_root_id:
self._print_root_port(self.rootPort_ID)
if changed_root or changed_root_id:
self.forwarding_table = ForwardingTable()
for port in self.ports:
self._designate_port(port)
self._enable_or_disable(port)
self._broadcast_BPDU()
def _received_data_logic(self, data_in, port, message):
"""
This function holds the functionality needed for when a data message is received. After it is
Received, if the port is enabled, the message is either forwarded on a different port, if
the address is in the forwarding table, broadcasted if the address isn't (or has expired),
or not broadcasted (if the forwarding table says that the address is on the incoming port,
or if the incoming port is disabled)
:param data_in: the DataMessage object to send
:param port: the port that the message came in on
:param message: the raw json message to send (so no re-encoding is needed)
:return: Void
"""
if data_in:
if port.enabled:
self._print_received_message(data_in.id, port.port_id, data_in.source, data_in.dest)
self.forwarding_table.add_address(data_in.source, port.port_id)
sending_port_id = self.forwarding_table.get_address_port(data_in.dest)
if sending_port_id >= 0 and self.ports[sending_port_id].enabled:
if self.ports[sending_port_id].BPDU_list and self.ports[sending_port_id].remove_timedout_BPDU(self.ports[sending_port_id].BPDU_list[0]):
self.forwarding_table = ForwardingTable()
self._print_boradcasting_message(data_in.id)
self._broadcast_message(message, port)
else:
if sending_port_id == port.port_id:
self._print_not_forwarding_message(data_in.id)
else:
self._print_forwarding_message(data_in.id, port.port_id)
self.ports[sending_port_id].socket.send(message)
else:
self._print_boradcasting_message(data_in.id)
self._broadcast_message(message, port)
else:
self._print_not_forwarding_message(data_in.id)
def _enable_or_disable(self, port):
"""
This function simply checks if the port is designated or root.
If neither, it sets it to disabled. If either,it gets set to enabled.
:param port: the port to check
:return: Void
"""
previous_status = port.enabled
if port.designated or self.rootPort_ID == port.port_id:
port.enabled = True
if previous_status != port.enabled:
self.forwarding_table = ForwardingTable()
else:
port.enabled = False
if previous_status != port.enabled:
self._print_disabled_port(port.port_id)
self.forwarding_table = ForwardingTable()
def __init__(self, bridgeID):
"""
creates a new Bridge
@param bridgeID : unique bridge id, set
@param LAN_list : default to empty list, else, will hold the LANs
"""
self.id = bridgeID
self.rootPort_ID = None
self.bridge_BPDU = BPDU(self.id, 'ffff', 1, self.id, 0)
self.ports = []
self.sockets = {}
self.forwarding_table = ForwardingTable()
def start_receiving(self):
"""
This function starts by broadcasting a BPDU, then runs the main loop
for a Bridge that receives and sends messages and BPDUs to specific
ports, and takes care of broadcasting BPDUs and messages to all ports
"""
start_time = time.time()
self._broadcast_BPDU()
while True:
self._initial_port_checks()
# is it time to send a new BPDU?
if int(round((time.time() - start_time) * 1000)) > 500:
self._broadcast_BPDU()
start_time = time.time()
ready, ignore, ignore2 = select.select([port.socket for port in self.ports], [], [], 0.1)
for x in ready:
port = self.ports[self.sockets[x]]
if not port.BPDU_list:
# if port not designated, print out designated
if not port.designated:
self._print_designated_port(port.port_id)
self.forwarding_table = ForwardingTable()
port.designated = True
self._enable_or_disable(port)
message = port.socket.recv(RECEIVE_SIZE)
message_json = json.loads(message)
if message_json['type'] == 'bpdu':
bpdu_in = BPDU(message_json['source'], message_json['dest'], message_json['message']['id'], message_json['message']['root'], message_json['message']['cost'])# + 1)
self._received_bpdu_logic(bpdu_in, port)
elif message_json['type'] == 'data':
data_in = create_DataMessage_from_json(message)
self._received_data_logic(data_in, port, message)
class Bridge:
"""
This is the class for a Bridge, which contains all the information
for a network bridge
"""
def __init__(self, bridgeID):
"""
creates a new Bridge
@param bridgeID : unique bridge id, set
@param LAN_list : default to empty list, else, will hold the LANs
"""
self.id = bridgeID
self.rootPort_ID = None
self.bridge_BPDU = BPDU(self.id, 'ffff', 1, self.id, 0)
self.ports = []
self.sockets = {}
self.forwarding_table = ForwardingTable()
def create_ports_for_lans(self, LAN_list):
"""
Creates a new socket with a respective port for each
LAN in the LAN_list
@LAN_list : List of LANs to create sockets for
"""
print "Bridge " + self.id + " starting up\n"
iterator = 0
unique_lan_list = []
for lan in LAN_list:
if lan not in unique_lan_list:
unique_lan_list.append(lan)
for lan in unique_lan_list:
s = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
s.connect(self._pad(lan))
port = Port(iterator, s)
self.ports.append(port)
self.sockets[s] = port.port_id
iterator += 1
self.start_receiving()
def start_receiving(self):
"""
This function starts by broadcasting a BPDU, then runs the main loop
for a Bridge that receives and sends messages and BPDUs to specific
ports, and takes care of broadcasting BPDUs and messages to all ports
"""
start_time = time.time()
self._broadcast_BPDU()
while True:
self._initial_port_checks()
# is it time to send a new BPDU?
if int(round((time.time() - start_time) * 1000)) > 500:
self._broadcast_BPDU()
start_time = time.time()
ready, ignore, ignore2 = select.select([port.socket for port in self.ports], [], [], 0.1)
for x in ready:
port = self.ports[self.sockets[x]]
if not port.BPDU_list:
# if port not designated, print out designated
if not port.designated:
self._print_designated_port(port.port_id)
self.forwarding_table = ForwardingTable()
port.designated = True
self._enable_or_disable(port)
message = port.socket.recv(RECEIVE_SIZE)
message_json = json.loads(message)
if message_json['type'] == 'bpdu':
bpdu_in = BPDU(message_json['source'], message_json['dest'], message_json['message']['id'], message_json['message']['root'], message_json['message']['cost'])# + 1)
self._received_bpdu_logic(bpdu_in, port)
elif message_json['type'] == 'data':
data_in = create_DataMessage_from_json(message)
self._received_data_logic(data_in, port, message)
def _initial_port_checks(self):
"""
This function runs the initial checks for all the ports, including removing all timedout BPDUs,
checking to see if the root has changed (if so, set it), and then designating and enabling/disabling ports.
:return: Void
"""
for port in self.ports:
port.remove_all_timedout_BPDUs()
# get a sorted list of the best BPDUs of all the ports
best_bpdu_list = sorted([(p, p.BPDU_list[0]) for p in self.ports if len(p.BPDU_list)], key=lambda tup: tup[1])
if len(best_bpdu_list):
best_bpdu = best_bpdu_list[0][1]
best_port = best_bpdu_list[0][0]
if self.id < best_bpdu.root:
self.rootPort_ID = None
self.bridge_BPDU = BPDU(self.id, 'ffff', 1, self.id, 0)
self._broadcast_BPDU()
if self.rootPort_ID:
if not len(self.ports[self.rootPort_ID].BPDU_list) or (self.ports[self.rootPort_ID].BPDU_list[0].is_incoming_BPDU_better(best_bpdu) and best_bpdu.source != self.ports[self.rootPort_ID].BPDU_list[0].source):
self._change_root(best_port, best_bpdu)
for port in self.ports:
self._designate_port(port)
self._enable_or_disable(port)
def _received_bpdu_logic(self, bpdu, port):
"""
This function handles all of the logic for when a BPDU message is received. It also takes care
of if the root port changed, if that port should now be designated or not
:param bpdu: the incoming BPDU
:param port: the port that the BPDU came in on
:return: Void
"""
self._port_decisions(bpdu, port)
def _received_data_logic(self, data_in, port, message):
"""
This function holds the functionality needed for when a data message is received. After it is
Received, if the port is enabled, the message is either forwarded on a different port, if
the address is in the forwarding table, broadcasted if the address isn't (or has expired),
or not broadcasted (if the forwarding table says that the address is on the incoming port,
or if the incoming port is disabled)
:param data_in: the DataMessage object to send
:param port: the port that the message came in on
:param message: the raw json message to send (so no re-encoding is needed)
:return: Void
"""
if data_in:
if port.enabled:
self._print_received_message(data_in.id, port.port_id, data_in.source, data_in.dest)
self.forwarding_table.add_address(data_in.source, port.port_id)
sending_port_id = self.forwarding_table.get_address_port(data_in.dest)
if sending_port_id >= 0 and self.ports[sending_port_id].enabled:
if self.ports[sending_port_id].BPDU_list and self.ports[sending_port_id].remove_timedout_BPDU(self.ports[sending_port_id].BPDU_list[0]):
self.forwarding_table = ForwardingTable()
self._print_boradcasting_message(data_in.id)
self._broadcast_message(message, port)
else:
if sending_port_id == port.port_id:
self._print_not_forwarding_message(data_in.id)
else:
self._print_forwarding_message(data_in.id, port.port_id)
self.ports[sending_port_id].socket.send(message)
else:
self._print_boradcasting_message(data_in.id)
self._broadcast_message(message, port)
else:
self._print_not_forwarding_message(data_in.id)
def _port_decisions(self, bpdu_in, port_in):
"""
This function holds all of the decisions for a port when a BPDU comes in.
- If the bridge currently think's it's the root, it checks if the BPDU holds a better path than this
bridge to a better root, if so, this bridge takes on the new path and information.
- If this bridge is not the root, it checks if the incoming BPDU is better than any seen on the incoming port,
if so, it then checks if it is also better than the bridge. If so, it takes on the new path. If it isn't
better than the bridge, but still better than the port, the port's designated status gets set to false.
- If this bridge is not the root, and the BPDU is not better than what is on this port, then the port gets
undesignated
:param bpdu_in: the incoming BPDU
:param port_in: the incoming port
:return: Void
"""
# if this bridge is currently the ROOT...
if self.rootPort_ID is None:
# if incoming BPDU has a better bridge than this one
if self.bridge_BPDU.is_incoming_BPDU_better(bpdu_in):
self._change_root(port_in, bpdu_in)
# if this bridge is currently NOT the root...
else:
# if the incoming BPDU is better than the current port's bpdu (seeing a better bridge)
if not len(port_in.BPDU_list) or port_in.BPDU_list[0].is_incoming_BPDU_better(bpdu_in):
# if the incoming BPDU is better than this root BPDU
if not len(self.ports[self.rootPort_ID].BPDU_list) or self.ports[self.rootPort_ID].BPDU_list[0].is_incoming_BPDU_better(bpdu_in):
# if the incoming bpdu's source is not the same as this bridge's current root port's bpdu's source
self._change_root(port_in, bpdu_in)
port_in.add_BPDU(bpdu_in)
self._designate_port(port_in)
self._enable_or_disable(port_in)
def _designate_port(self, port):
"""
This function takes in a port and decides if it should be designated or not. This
is decided by if the port's BPDU list is empty or the bridge BPDU is better than
the best BPDU received on that port
:param port:
:return:
"""
if not len(port.BPDU_list) or port.BPDU_list[0].is_incoming_BPDU_better(self.bridge_BPDU):
port.designated = True
else:
port.designated = False
def _change_root(self, port_in, bpdu_in):
"""
This function updates the root information for the incoming BPDU on the port_in
Since this is used a few times, this function was created to minimize redundancy
:param port_in: the port the bpdu was received on
:param bpdu_in: the bpdu that will update this bridge's root information
:return: Void
"""
changed_root = self.bridge_BPDU.root != bpdu_in.root
changed_root_id = self.rootPort_ID != port_in.port_id
self.bridge_BPDU = BPDU(self.id, 'ffff', 1, bpdu_in.root, bpdu_in.cost + 1)
if changed_root:
self._print_new_root()
# set bridge's root port to this port
self.rootPort_ID = port_in.port_id
port_in.designated = False
if changed_root_id:
self._print_root_port(self.rootPort_ID)
if changed_root or changed_root_id:
self.forwarding_table = ForwardingTable()
for port in self.ports:
self._designate_port(port)
self._enable_or_disable(port)
self._broadcast_BPDU()
def _enable_or_disable(self, port):
"""
This function simply checks if the port is designated or root.
If neither, it sets it to disabled. If either,it gets set to enabled.
:param port: the port to check
:return: Void
"""
previous_status = port.enabled
if port.designated or self.rootPort_ID == port.port_id:
port.enabled = True
if previous_status != port.enabled:
self.forwarding_table = ForwardingTable()
else:
port.enabled = False
if previous_status != port.enabled:
self._print_disabled_port(port.port_id)
self.forwarding_table = ForwardingTable()
def _broadcast_BPDU(self):
"""
Broadcasts a new BPDU from this bridge to all sockets on the bridge
@return: Void
"""
for port in self.ports:
json_bridge_bpdu = self.bridge_BPDU.create_json_BPDU()
port.socket.send(json_bridge_bpdu)
def _broadcast_message(self, message, port_in):
"""
Broadcasts the given message to all socket connections, except the
given port
@param message : string
@return: Void
"""
for port in self.ports:
if port.port_id != port_in.port_id:
self._enable_or_disable(port)
if port.enabled:
port.socket.send(message)
def _send_to_address(self, message, dest_port_id):
"""
Sends the message inputted to the input address directly,
using the forwarding table entry
@param message : message to Sends
@param address : address to send to
@return Void
"""
#port_id = self.forwarding_table.get_address_port(address)
#if self.ports[port_id].enabled:
self.ports[dest_port_id].socket.send(message)
def _pad(self, name):
"""
Pads the name with null bytes at the end
@param name : the name to pad
@return String
"""
result = '\0' + name
while len(result) < 108:
result += '\0'
return result
def _print_received_message(self, data_in_id, port_port_id, data_in_source, data_in_dest):
"""
This function prints that a message was received on the port
:param data_in_id: the ID of the message
:param port_port_id: the port that the message came in on
:param data_in_source: the source of the message
:param data_in_dest: the destination of the message
:return: Void
"""
print "Received message " + str(data_in_id) + "on port " + str(port_port_id) + \
" from " + str(data_in_source) + " to " + str(data_in_dest)
def _print_forwarding_message(self, data_in_id, port_port_id):
"""
This function prints that the message was forwarded to the given port
:param data_in_id: the message ID
:param port_port_id: the port that the message was forwarded on
:return: Void
"""
print "Forwarding message " + str(data_in_id) + " to port " + str(port_port_id)
def _print_boradcasting_message(self, data_in_id):
"""
This function prints that a message is being broadcasted on all ports (except the incoming port)
:param data_in_id: the message ID
:return: Void
"""
print "Broadcasting message " + str(data_in_id) + " to all ports"
def _print_not_forwarding_message(self, data_in_id):
"""
This function prints that the message is not being forwarded
:param data_in_id: the message ID
:return: Void
"""
print "Not forwarding message " + str(data_in_id)
def _print_disabled_port(self, port_id):
"""
This function prints that the given port was disabled
:param port_id: the ID of the port being disabled
:return: Void
"""
print "Disabled port: " + str(self.id) + "/" + str(port_id)
def _print_new_root(self):
"""
This function prints that a new root was found for this bridge
:return: Void
"""
print "New root: " + str(self.id) + "/" + str(self.bridge_BPDU.root)
def _print_root_port(self, port_id):
"""
This function prints that this bridge has a new root port
:param port_id: the new root port id
:return: Void
"""
print "Root port: " + str(self.id) + "/" + str(port_id)
def _print_designated_port(self, port_id):
"""
This function prints that this port is designated
:param port_id: the port being designated
:return: Void
"""
print "Designated port: " + str(self.id) + "/" + str(port_id)
def _print_bridge_info(self):
"""
This function is used to print out all of the information on this bridge, including the status of it's ports.
Useful when debugging tree.
:return: Void
"""
port_status_list = ""
for port in self.ports:
port_status_list += "\tPort-" + str(port.port_id) + "-Enabled=" + str(port.enabled) + "-Designated=" + str(port.designated)
print "BRIDGE - " + str(self.id) + " ROOT= " + str(self.bridge_BPDU.root) + " COST= " + str(self.bridge_BPDU.cost) + " ROOT PORT= " + str(self.rootPort_ID) + " PORTS:[" + str(port_status_list) + "]\n"