137 lines
4.7 KiB
Ruby
137 lines
4.7 KiB
Ruby
# $Id: igrp.rb 14 2008-03-02 05:42:30Z warchild $
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#
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# Copyright (c) 2008, Jon Hart
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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# * Neither the name of the <organization> nor the
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# names of its contributors may be used to endorse or promote products
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# derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY Jon Hart ``AS IS'' AND ANY
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# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL Jon Hart BE LIABLE FOR ANY
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# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# Internet Gateway Routing Protocol: IGRP
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#
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# http://www.cisco.com/warp/public/103/5.html
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#
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# Every routing entry has the following fields:
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# uchar number[3]; /* 3 significant octets of IP address */
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# uchar delay[3]; /* delay, in tens of microseconds */
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# uchar bandwidth[3]; /* bandwidth, in units of 1 Kbit/sec */
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# uchar mtu[2]; /* MTU, in octets */
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# uchar reliability; /* percent packets successfully tx/rx */
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# uchar load; /* percent of channel occupied */
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# uchar hopcount; /* hop count */
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module Racket
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class IGRP < RacketPart
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IGRP_UPDATE = 1
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IGRP_REQUEST = 2
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# Version of the IGRP message contained in this packet.
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# Defaults to 1. Anything else is currently invalid
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unsigned :version, 4, { :default => 1 }
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# Type of the IGRP message contained in this packet.
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unsigned :opcode, 4
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# Serial number which is incremented whenever the routing
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# table is updated.
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unsigned :edition, 8
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# Autonomous system number
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unsigned :asystem, 16
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# Number of interior routes contained in this update message
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unsigned :ninterior, 16
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# Number of system routes contained in this update message
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unsigned :nsystem, 16
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# Number of exterior routes contained in this update message
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unsigned :nexterior, 16
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# Checksum (IP)
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unsigned :checksum, 16
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# Payload. Generally unused.
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rest :payload
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def initialize(*args)
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@interior_routes = []
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@system_routes = []
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@exterior_routes = []
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super
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end
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# Add a system route to this IGRP packet
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def add_system(ip, delay, bw, mtu, rel, load, hop)
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@system_routes << add_entry(ip, delay, bw, mtu, rel, load, hop)
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self.nsystem += 1
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end
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# Add an interior route to this IGRP packet
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def add_interior(ip, delay, bw, mtu, rel, load, hop)
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@interior_routes << add_entry(ip, delay, bw, mtu, rel, load, hop)
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self.ninterior += 1
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end
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# Add an exterior route to this IGRP packet
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def add_exterior(ip, delay, bw, mtu, rel, load, hop)
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@exterior_routes << add_entry(ip, delay, bw, mtu, rel, load, hop)
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self.nexterior += 1
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end
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# Compute and set the checksum of this IGRP packet
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def checksum!
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self.checksum = compute_checksum
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end
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# Is the checksum correct?
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def checksum?
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self.checksum == compute_checksum
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end
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# Fix everything up in preparation for sending.
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def fix!
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[@interior_routes, @system_routes, @exterior_routes].flatten.each do |r|
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self.payload += r
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end
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checksum!
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end
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private
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def add_entry(ip, delay, bw, mtu, rel, load, hop)
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# tmp should be 12 bytes long
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tmp = ((((((((ip << 8*3) | delay) << 8*3) | bw) << 8*2) | mtu) << 8*1)| rel)
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# now split it up into 3, 4-byte chunks suitable for an 'N' pack
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tmp1 = (0xffffffff0000000000000000 & tmp) >> 8*8
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tmp2 = (0x00000000ffffffff00000000 & tmp) >> 8*4
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tmp3 = (0x0000000000000000ffffffff & tmp)
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[tmp1, tmp2, tmp3, load, hop].pack("NNNCC")
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end
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def compute_checksum
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tmp = []
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tmp << (self.version << 4 | self.opcode)
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tmp << self.edition
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tmp << self.asystem
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tmp << self.ninterior
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tmp << self.nsystem
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tmp << self.nexterior
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tmp << 0
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tmp << payload
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L3::Misc.checksum(tmp.pack("Cnnnnnna*"))
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end
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end
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end
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# vim: set ts=2 et sw=2:
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