114 lines
3.6 KiB
Ruby
114 lines
3.6 KiB
Ruby
# -*- coding: binary -*-
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module Net # :nodoc:
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module DNS
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module Names # :nodoc: all
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INT16SZ = 2
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# Expand a compressed name in a DNS Packet object. Please
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# see RFC1025 for an explanation of how the compression
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# in DNS packets works, how may it be useful and how should
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# be handled.
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#
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# This method accept two parameters: a raw packet data and an
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# offset, which indicates the point in the packet in which the
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# parsing has arrived.
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#
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def dn_expand(packet,offset)
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name = ""
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packetlen = packet.size
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while true
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raise ExpandError, "offset is greater than packet lenght!" if packetlen < (offset+1)
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len = packet.unpack("@#{offset} C")[0]
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if len == 0
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offset += 1
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break
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elsif (len & 0xC0) == 0xC0
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raise ExpandError, "Packet ended before offset expand" if packetlen < (offset+INT16SZ)
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ptr = packet.unpack("@#{offset} n")[0]
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ptr &= 0x3FFF
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name2 = dn_expand(packet,ptr)[0]
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raise ExpandError, "Packet is malformed!" if name2 == nil
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name += name2
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offset += INT16SZ
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break
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else
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offset += 1
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raise ExpandError, "No expansion found" if packetlen < (offset+len)
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elem = packet[offset..offset+len-1]
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name += "#{elem}."
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offset += len
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end
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end
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return [name,offset] # name.chomp(".") if trailing dot has to be omitted
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end
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def pack_name(name)
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if name.size > 255
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raise ArgumentError, "Name data cannot exceed 255 chars"
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end
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arr = name.split(".")
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str = ""
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arr.each do |elem|
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if elem.size > 63
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raise ArgumentError, "Label data cannot exceed 63 chars"
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end
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str += [elem.size,elem].pack("Ca*")
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end
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str += [0].pack("C")
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str
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end
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def names_array(name)
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arr = name.split(".")
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ar = []
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string = ""
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arr.size.times do |i|
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x = i+1
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elem = arr[-x]
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len = elem.size
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string = ((string.reverse)+([len,elem].pack("Ca*")).reverse).reverse
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ar.unshift(string)
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end
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return ar
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end
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def dn_comp(name,offset,compnames)
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names = {}
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ptr = 0
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str = ""
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arr = names_array(name)
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arr.each do |entry|
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if compnames.has_key?(entry)
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ptr = 0xC000 | compnames[entry]
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str += [ptr].pack("n")
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offset += INT16SZ
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break
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else
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len = entry.unpack("C")[0]
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elem = entry[1..len]
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str += [len,elem].pack("Ca*")
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names.update({"#{entry}" => offset})
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offset += len
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end
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end
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return str,offset,names
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end
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def valid?(name)
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if name =~ /^([a-z0-9]([-a-z0-9]*[a-z0-9])?\.)+((a[cdefgilmnoqrstuwxz]|aero|arpa)|(b[abdefghijmnorstvwyz]|biz)|(c[acdfghiklmnorsuvxyz]|cat|com|coop)|d[ejkmoz]|(e[ceghrstu]|edu)|f[ijkmor]|(g[abdefghilmnpqrstuwy]|gov)|h[kmnrtu]|(i[delmnoqrst]|info|int)|(j[emop]|jobs)|k[eghimnprwyz]|l[abcikrstuvy]|(m[acdghklmnopqrstuvwxyz]|mil|mobi|museum)|(n[acefgilopruz]|name|net)|(om|org)|(p[aefghklmnrstwy]|pro)|qa|r[eouw]|s[abcdeghijklmnortvyz]|(t[cdfghjklmnoprtvwz]|travel)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw])$/i
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return name
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else
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raise ArgumentError, "Invalid FQDN: #{name}"
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end
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end
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end # module Names
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end # module DNS
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end # module Net
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class ExpandError < StandardError # :nodoc:
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end
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