| # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import dpkt |
| import socket |
| |
| from lansim import tools |
| |
| class SimpleHost(object): |
| """A simple host supporting IPv4. |
| |
| This class is useful as a base clase to implement other hosts. It supports |
| a single IPv4 address. |
| """ |
| def __init__(self, sim, hw_addr, ip_addr): |
| """Creates the host and associates it with the given NetworkBridge. |
| |
| @param sim: The Simulator interface where this host lives. |
| @param hw_addr: Hex or binary representation of the Ethernet address. |
| @param ip_addr: The IPv4 address. For example: "10.0.0.1". |
| """ |
| self._sim = sim |
| self._hw_addr = hw_addr |
| self._ip_addr = ip_addr |
| self._bin_hw_addr = tools.inet_hwton(hw_addr) |
| self._bin_ip_addr = socket.inet_aton(ip_addr) |
| # Reply to broadcast ARP requests. |
| rule = { |
| "dst": "\xff" * 6, # Broadcast HW addr. |
| "arp.pln": 4, # Protocol Addres Length is 4 (IP v4). |
| "arp.op": dpkt.arp.ARP_OP_REQUEST, |
| "arp.tpa": self._bin_ip_addr} |
| sim.add_match(rule, self.arp_request) |
| |
| # Reply to unicast ARP requests. |
| rule["dst"] = self._bin_hw_addr |
| sim.add_match(rule, self.arp_request) |
| |
| def arp_request(self, pkt): |
| """Sends the ARP_REPLY matching the request. |
| |
| @param pkt: a dpkt.Packet with the ARP_REQUEST. |
| """ |
| arp_resp = dpkt.arp.ARP( |
| op = dpkt.arp.ARP_OP_REPLY, |
| pln = 4, |
| tpa = pkt.arp.spa, # Target Protocol Address. |
| tha = pkt.arp.sha, # Target Hardware Address. |
| spa = self._bin_ip_addr, # Source Protocol Address. |
| sha = self._bin_hw_addr) # Source Hardware Address. |
| eth_resp = dpkt.ethernet.Ethernet( |
| dst = pkt.arp.sha, |
| src = self._bin_hw_addr, |
| type = dpkt.ethernet.ETH_TYPE_ARP, |
| data = arp_resp) |
| self._sim.write(eth_resp) |
| |
| |
