def addApplication(self, appName, appType):
"""Creates an application 'appName' of the specified type."""
if appType == 'ircc':
self.application = IrcClient(self.ipAddr)
# Only the IRC client can be controlled
# directly by simulation commands
elif appType == 'ircs':
self.application = IrcServer(self.ipAddr)
self.simQueue = None
elif appType == 'dnss':
self.application = DnsServer(self.ipAddr)
self.simQueue = None
def addApplication(self, appName, appType):
"""Creates an application 'appName' of the specified type."""
if appType == 'ircc':
self.application = IrcClient(self.ipAddr)
# Only the IRC client can be controlled
# directly by simulation commands
elif appType == 'ircs':
self.application = IrcServer(self.ipAddr)
self.simQueue = None
elif appType == 'dnss':
self.application = DnsServer(self.ipAddr)
self.simQueue = None
class Host:
def __init__(self, name):
"""Initializes a computer with the given hostname."""
self.name = name
self.idCounter = 1
# Addresses
self.ipAddr = self.routerAddr = self.dnsAddr = None
# Application running on host and link to a router
self.application = None
self.link = None
# Network queue that receives commands from linked entities
self.simQueue = queue.Queue()
self.netQueue = queue.Queue()
# Default port for DNS and IRC servers
self.dnsPort = 53
self.ircPort = 6667
def setIp(self, ipAddr, routerAddr, dnsAddr):
"""Defines IP numbers for host, its router and DNS server."""
self.ipAddr = ipAddr
self.routerAddr = routerAddr
self.dnsAddr = dnsAddr
def addApplication(self, appName, appType):
"""Creates an application 'appName' of the specified type."""
if appType == 'ircc':
self.application = IrcClient(self.ipAddr)
# Only the IRC client can be controlled
# directly by simulation commands
elif appType == 'ircs':
self.application = IrcServer(self.ipAddr)
self.simQueue = None
elif appType == 'dnss':
self.application = DnsServer(self.ipAddr)
self.simQueue = None
def setDnsTable(self, dnsTable):
"""Defines the DNS table for a DNS server application."""
try:
self.application.setDnsTable(dnsTable)
except NameError:
print(self.name, "isn't a DNS server!")
def getNetQueue(self):
"""Returns the host's network queue."""
return self.netQueue
def addSimQueue(self, msg):
"""Adds a message to the host's simulator queue."""
self.simQueue.put(msg)
def addLink(self, link):
"""Links the host to a router's buffer queue."""
self.link = link
def setSniffer(self, sniffer):
"""Sets a sniffer between the host and the router
which it is linked to."""
self.link.setSniffer(sniffer)
def processCommand(self, command):
"""Processes a command received from the simulation."""
name = self.application.requireDns(command)
if name is not None:
# Connect to DNS server to ask for IP
command[1] = self.__dnsConnect(name)
if command[0] == "CONNECT":
self.__tcpEstablishConnection(command[1])
packet = self.application.send(command)
packet.setId(self.__nextPacketId())
self.link.putTargetQueue(packet)
# IRC Client must wait for ACK packet
packet = self.netQueue.get()
if packet.getSegment().getMessage() != "":
raise Exception("Must get an ACK packet!")
self.netQueue.task_done()
def processPacket(self, packet):
"""Processes a packet received from the network."""
respPacket = self.application.receive(packet)
if type(respPacket) is list:
for p in respPacket:
p.setId(self.__nextPacketId())
self.link.putTargetQueue(p)
if p.getSegment().getFIN() is True:
self.__tcpCloseConnection(p)
elif respPacket is not None:
respPacket.setId(self.__nextPacketId())
self.link.putTargetQueue(respPacket)
def runThread(self):
"""Host's infinite thread loop. Receives and sends messages
to other hosts."""
while True:
if self.simQueue is not None:
# Read and process a direct simulator command
command = self.simQueue.get()
self.processCommand(command)
self.simQueue.task_done()
# Read and process network command
packet = self.netQueue.get()
self.processPacket(packet)
self.netQueue.task_done()
def __nextPacketId(self):
"""Returns a unique ID to be given to a packet."""
packetId = self.name + " #" + str(self.idCounter)
self.idCounter += 1
return packetId
def __tcpEstablishConnection(self, serverIp):
"""Establishes a TCP connection by doing a handshake with
the server."""
clientPort = random.randint(1025, 65530)
# Sends a SYN message to establish connection
segment = TcpSegment("", clientPort, self.ircPort)
segment.setSYN()
datagram = IpDatagram(segment, self.ipAddr, serverIp)
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
packet = self.netQueue.get()
# Receives packet containing server's SYN
segment = TcpSegment("", clientPort, self.ircPort)
segment.setAckNumber(packet.getSegment().getAckNumber())
segment.setACK()
segment.setSeqNumber(1)
segment.setSeqNumber(1)
datagram = IpDatagram(segment, self.ipAddr, packet.getOriginIp())
self.netQueue.task_done()
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
# Defines the randomized client port number
self.application.setClientPort(clientPort)
def __tcpCloseConnection(self, finalPacket):
"""Close TCP connection by doing a handshake with
the server."""
serverIp = finalPacket.getDestinationIp()
clientPort = finalPacket.getSegment().getOriginPort()
# Sends a FIN/ACK message to close connection
packet = self.netQueue.get()
# Receives packet containing server's SYN
segment = TcpSegment("", clientPort, self.ircPort)
segment.setAckNumber(packet.getSegment().getAckNumber())
segment.setACK()
segment.setSeqNumber(packet.getSegment().getAckNumber())
segment.setAckNumber(packet.getSegment().getSeqNumber() + 1)
datagram = IpDatagram(segment, self.ipAddr, packet.getOriginIp())
self.netQueue.task_done()
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
def __dnsConnect(self, name):
"""Connects to the DNS server to obtain the given name's
corresponding IP."""
segment = UdpSegment(name, 2000, self.dnsPort)
datagram = IpDatagram(segment, self.ipAddr, self.dnsAddr)
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
packet = self.netQueue.get()
ip = packet.getSegment().getMessage().split(',')[1]
self.netQueue.task_done()
return ip
class Host:
def __init__(self, name):
"""Initializes a computer with the given hostname."""
self.name = name
self.idCounter = 1
# Addresses
self.ipAddr = self.routerAddr = self.dnsAddr = None
# Application running on host and link to a router
self.application = None
self.link = None
# Network queue that receives commands from linked entities
self.simQueue = queue.Queue()
self.netQueue = queue.Queue()
# Default port for DNS and IRC servers
self.dnsPort = 53
self.ircPort = 6667
def setIp(self, ipAddr, routerAddr, dnsAddr):
"""Defines IP numbers for host, its router and DNS server."""
self.ipAddr = ipAddr
self.routerAddr = routerAddr
self.dnsAddr = dnsAddr
def addApplication(self, appName, appType):
"""Creates an application 'appName' of the specified type."""
if appType == 'ircc':
self.application = IrcClient(self.ipAddr)
# Only the IRC client can be controlled
# directly by simulation commands
elif appType == 'ircs':
self.application = IrcServer(self.ipAddr)
self.simQueue = None
elif appType == 'dnss':
self.application = DnsServer(self.ipAddr)
self.simQueue = None
def setDnsTable(self, dnsTable):
"""Defines the DNS table for a DNS server application."""
try:
self.application.setDnsTable(dnsTable)
except NameError:
print(self.name, "isn't a DNS server!")
def getNetQueue(self):
"""Returns the host's network queue."""
return self.netQueue
def addSimQueue(self, msg):
"""Adds a message to the host's simulator queue."""
self.simQueue.put(msg)
def addLink(self, link):
"""Links the host to a router's buffer queue."""
self.link = link
def setSniffer(self, sniffer):
"""Sets a sniffer between the host and the router
which it is linked to."""
self.link.setSniffer(sniffer)
def processCommand(self, command):
"""Processes a command received from the simulation."""
name = self.application.requireDns(command)
if name is not None:
# Connect to DNS server to ask for IP
command[1] = self.__dnsConnect(name)
if command[0] == "CONNECT":
self.__tcpEstablishConnection(command[1])
packet = self.application.send(command)
packet.setId(self.__nextPacketId())
self.link.putTargetQueue(packet)
# IRC Client must wait for ACK packet
packet = self.netQueue.get()
if packet.getSegment().getMessage() != "":
raise Exception("Must get an ACK packet!")
self.netQueue.task_done()
def processPacket(self, packet):
"""Processes a packet received from the network."""
respPacket = self.application.receive(packet)
if type(respPacket) is list:
for p in respPacket:
p.setId(self.__nextPacketId())
self.link.putTargetQueue(p)
if p.getSegment().getFIN() is True:
self.__tcpCloseConnection(p)
elif respPacket is not None:
respPacket.setId(self.__nextPacketId())
self.link.putTargetQueue(respPacket)
def runThread(self):
"""Host's infinite thread loop. Receives and sends messages
to other hosts."""
while True:
if self.simQueue is not None:
# Read and process a direct simulator command
command = self.simQueue.get()
self.processCommand(command)
self.simQueue.task_done()
# Read and process network command
packet = self.netQueue.get()
self.processPacket(packet)
self.netQueue.task_done()
def __nextPacketId(self):
"""Returns a unique ID to be given to a packet."""
packetId = self.name + " #" + str(self.idCounter)
self.idCounter += 1
return packetId
def __tcpEstablishConnection(self, serverIp):
"""Establishes a TCP connection by doing a handshake with
the server."""
clientPort = random.randint(1025, 65530)
# Sends a SYN message to establish connection
segment = TcpSegment("", clientPort, self.ircPort)
segment.setSYN()
datagram = IpDatagram(segment, self.ipAddr, serverIp)
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
packet = self.netQueue.get()
# Receives packet containing server's SYN
segment = TcpSegment("", clientPort, self.ircPort)
segment.setAckNumber(packet.getSegment().getAckNumber())
segment.setACK()
segment.setSeqNumber(1)
segment.setSeqNumber(1)
datagram = IpDatagram(segment, self.ipAddr, packet.getOriginIp())
self.netQueue.task_done()
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
# Defines the randomized client port number
self.application.setClientPort(clientPort)
def __tcpCloseConnection(self, finalPacket):
"""Close TCP connection by doing a handshake with
the server."""
serverIp = finalPacket.getDestinationIp()
clientPort = finalPacket.getSegment().getOriginPort()
# Sends a FIN/ACK message to close connection
packet = self.netQueue.get()
# Receives packet containing server's SYN
segment = TcpSegment("", clientPort, self.ircPort)
segment.setAckNumber(packet.getSegment().getAckNumber())
segment.setACK()
segment.setSeqNumber(packet.getSegment().getAckNumber())
segment.setAckNumber(packet.getSegment().getSeqNumber() + 1)
datagram = IpDatagram(segment, self.ipAddr, packet.getOriginIp())
self.netQueue.task_done()
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
def __dnsConnect(self, name):
"""Connects to the DNS server to obtain the given name's
corresponding IP."""
segment = UdpSegment(name, 2000, self.dnsPort)
datagram = IpDatagram(segment, self.ipAddr, self.dnsAddr)
datagram.setId(self.__nextPacketId())
self.link.putTargetQueue(datagram)
packet = self.netQueue.get()
ip = packet.getSegment().getMessage().split(',')[1]
self.netQueue.task_done()
return ip
