77 lines
2.7 KiB
Ruby
77 lines
2.7 KiB
Ruby
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# $Id: cdp.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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# CDP -- Cisco Discovery Protocol
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# http://www.cisco.biz/univercd/cc/td/doc/product/lan/trsrb/frames.htm#xtocid12
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class CDP < RacketPart
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# CDP Version (generally 1)
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unsigned :version, 8, { :default => 1 }
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# Time-to-live of the data in this message
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unsigned :ttl, 8
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# Checksum
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unsigned :csum, 16
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# Payload of this CDP message. Generally untouched.
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rest :payload
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# Add a new field to this CDP message.
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def add_field(type, value)# {{{
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t = TLV.new(2,2)
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t.type = type
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t.value = value
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t.length = 4 + value.length
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self.payload += t.encode
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end# }}}
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# Check the checksum for this IP datagram
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def checksum?# {{{
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self.csum == compute_checksum
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end# }}}
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# Compute and set the checksum for this IP datagram
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def checksum!# {{{
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self.csum = compute_checksum
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end# }}}
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# Fix this CDP message up for sending.
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def fix!# {{{
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self.checksum!
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end# }}}
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private
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# Compute the checksum for this IP datagram
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def compute_checksum# {{{
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pseudo = []
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pseudo << ((self.version << 8) | self.ttl)
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pseudo << 0
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pseudo << self.payload
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L3::Misc.checksum(pseudo.pack("nna*"))
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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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