from __future__ import division from collections import deque import itertools from sim import logger, sleep, simulator log = lambda x: logger.log(x, 4) #link layer class Packet: """Represents a network packet.""" id_counter = itertools.count() def __init__(self, origin, dest, message): self.id = Link.id_counter.next() self.origin = origin self.dest = dest self.message = message @property def size(self): return (len(self.message) if self.message else 0) + 4 class Link: """Represents a unidirectional link.""" id_counter = itertools.count() def __init__(self, source, dest, prop_delay, bandwidth): """Creates a Link between the specified Hosts, with the given performance. (This also adds the Link to the source Host's outgoing links.)""" self.id = Link.id_counter.next() self.dest = dest
from link import Link
from sim import logger
log = lambda x: logger.log(x, 2) #transport layer
class Host:
"""Represent a host on the Internet.
Currently, a host may have exactly one IP address.
"""
def __init__(self, ip):
"""Construct a host with the given ip address."""
self.ip = ip
self.routing = {} #ip address to link
Link(self, self, 0, 100000)
# data transfer
#non-blocking
def send(self, packet):
"""Send packet."""
try:
self.routing[packet.dest].enqueue(packet)
except KeyError:
log('{host.ip} has no entry for {packet.dest}', host=self, packet=packet)
def received(self, packet):
"""Called (by Link) to deliver a packet to this Host."""
if packet.dest != self.ip:
log('{host.ip} received packet for ip {packet.dest}'.format(host=self, packet=packet))
log('{host.ip} received packet {packet.id}'.format(host=self, packet=packet))
