114 lines
3.6 KiB
Ruby
114 lines
3.6 KiB
Ruby
# -*- coding: binary -*-
|
|
module Net # :nodoc:
|
|
module DNS
|
|
|
|
module Names # :nodoc: all
|
|
|
|
INT16SZ = 2
|
|
|
|
# Expand a compressed name in a DNS Packet object. Please
|
|
# see RFC1025 for an explanation of how the compression
|
|
# in DNS packets works, how may it be useful and how should
|
|
# be handled.
|
|
#
|
|
# This method accept two parameters: a raw packet data and an
|
|
# offset, which indicates the point in the packet in which the
|
|
# parsing has arrived.
|
|
#
|
|
def dn_expand(packet,offset)
|
|
name = ""
|
|
packetlen = packet.size
|
|
while true
|
|
raise ExpandError, "offset is greater than packet length!" if packetlen < (offset+1)
|
|
len = packet.unpack("@#{offset} C")[0]
|
|
|
|
if len == 0
|
|
offset += 1
|
|
break
|
|
elsif (len & 0xC0) == 0xC0
|
|
raise ExpandError, "Packet ended before offset expand" if packetlen < (offset+INT16SZ)
|
|
ptr = packet.unpack("@#{offset} n")[0]
|
|
ptr &= 0x3FFF
|
|
name2 = dn_expand(packet,ptr)[0]
|
|
raise ExpandError, "Packet is malformed!" if name2 == nil
|
|
name += name2
|
|
offset += INT16SZ
|
|
break
|
|
else
|
|
offset += 1
|
|
raise ExpandError, "No expansion found" if packetlen < (offset+len)
|
|
elem = packet[offset..offset+len-1]
|
|
name += "#{elem}."
|
|
offset += len
|
|
end
|
|
end
|
|
return [name,offset] # name.chomp(".") if trailing dot has to be omitted
|
|
end
|
|
|
|
def pack_name(name)
|
|
if name.size > 255
|
|
raise ArgumentError, "Name data cannot exceed 255 chars"
|
|
end
|
|
arr = name.split(".")
|
|
str = ""
|
|
arr.each do |elem|
|
|
if elem.size > 63
|
|
raise ArgumentError, "Label data cannot exceed 63 chars"
|
|
end
|
|
str += [elem.size,elem].pack("Ca*")
|
|
end
|
|
str += [0].pack("C")
|
|
str
|
|
end
|
|
|
|
def names_array(name)
|
|
arr = name.split(".")
|
|
ar = []
|
|
string = ""
|
|
arr.size.times do |i|
|
|
x = i+1
|
|
elem = arr[-x]
|
|
len = elem.size
|
|
string = ((string.reverse)+([len,elem].pack("Ca*")).reverse).reverse
|
|
ar.unshift(string)
|
|
end
|
|
return ar
|
|
end
|
|
|
|
def dn_comp(name,offset,compnames)
|
|
names = {}
|
|
ptr = 0
|
|
str = ""
|
|
arr = names_array(name)
|
|
arr.each do |entry|
|
|
if compnames.has_key?(entry)
|
|
ptr = 0xC000 | compnames[entry]
|
|
str += [ptr].pack("n")
|
|
offset += INT16SZ
|
|
break
|
|
else
|
|
len = entry.unpack("C")[0]
|
|
elem = entry[1..len]
|
|
str += [len,elem].pack("Ca*")
|
|
names.update({"#{entry}" => offset})
|
|
offset += len
|
|
end
|
|
end
|
|
return str,offset,names
|
|
end
|
|
|
|
def valid?(name)
|
|
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
|
|
return name
|
|
else
|
|
raise ArgumentError, "Invalid FQDN: #{name}"
|
|
end
|
|
end
|
|
|
|
end # module Names
|
|
end # module DNS
|
|
end # module Net
|
|
|
|
class ExpandError < StandardError # :nodoc:
|
|
end
|