762 lines
23 KiB
Ruby
762 lines
23 KiB
Ruby
#---
|
|
# $Id: Header.rb,v 1.5 2006/07/30 16:54:28 bluemonk Exp $
|
|
#+++
|
|
|
|
require 'net/dns/dns'
|
|
|
|
module Net # :nodoc:
|
|
module DNS
|
|
|
|
#
|
|
# =Name
|
|
#
|
|
# Net::DNS::Header - DNS packet header class
|
|
#
|
|
# =Synopsis
|
|
#
|
|
# require 'net/dns/header'
|
|
#
|
|
# =Description
|
|
#
|
|
# The Net::DNS::Header class represents the header portion of a
|
|
# DNS packet. An Header object is created whenever a new packet
|
|
# is parsed or as user request.
|
|
#
|
|
# header = Net::DNS::Header.new
|
|
# # ;; id = 18123
|
|
# # ;; qr = 0 opCode: 0 aa = 0 tc = 0 rd = 1
|
|
# # ;; ra = 0 ad = 0 cd = 0 rcode = 0
|
|
# # ;; qdCount = 1 anCount = 0 nsCount = 0 arCount = 0
|
|
#
|
|
# header.format
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 18123 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # |0| 0 |0|0|1|0|0| 0 | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 1 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
#
|
|
# # packet is an instance of Net::DNS::Packet
|
|
# header = packet.header
|
|
# puts "Answer is #{header.auth? ? '' : 'non'} authoritative"
|
|
#
|
|
# A lot of methods were written to keep a compatibility layer with
|
|
# the Perl version of the library, as long as methods name which are
|
|
# more or less the same.
|
|
#
|
|
# =Error classes
|
|
#
|
|
# Some error classes has been defined for the Net::DNS::Header class,
|
|
# which are listed here to keep a light and browsable main documentation.
|
|
# We have:
|
|
#
|
|
# * HeaderArgumentError: canonical argument error
|
|
# * HeaderWrongCount: a wrong +count+ parameter has been passed
|
|
# * HeaderWrongRecursive: a wrong +recursive+ parameter has been passed
|
|
# * HeaderWrongOpcode: a not valid +opCode+ has been specified
|
|
# * HeaderDuplicateID: the requested ID is already in use
|
|
#
|
|
# =Copyright
|
|
#
|
|
# Copyright (c) 2006 Marco Ceresa
|
|
#
|
|
# All rights reserved. This program is free software; you may redistribute
|
|
# it and/or modify it under the same terms as Ruby itself.
|
|
#
|
|
class Header
|
|
|
|
#
|
|
# =Name
|
|
#
|
|
# Net::DNS::Header::RCode - DNS Header RCode handling class
|
|
#
|
|
# =Synopsis
|
|
#
|
|
# It should be used internally by Net::DNS::Header class. However, it's still
|
|
# possible to instantiate it directly.
|
|
#
|
|
# require 'net/dns/header'
|
|
# rcode = Net::DNS::Header::RCode.new 0
|
|
#
|
|
# =Description
|
|
#
|
|
# The RCode class represents the RCode field in the Header portion of a
|
|
# DNS packet. This field (called Response Code) is used to get informations
|
|
# about the status of a DNS operation, such as a query or an update. These
|
|
# are the values in the original Mockapetris's standard (RFC1035):
|
|
#
|
|
# * 0 No error condition
|
|
# * 1 Format error - The name server was unable to interpret
|
|
# the query.
|
|
# * 2 Server failure - The name server was
|
|
# unable to process this query due to a
|
|
# problem with the name server.
|
|
# * 3 Name Error - Meaningful only for
|
|
# responses from an authoritative name
|
|
# server, this code signifies that the
|
|
# domain name referenced in the query does
|
|
# not exist.
|
|
# * 4 Not Implemented - The name server does
|
|
# not support the requested kind of query.
|
|
# * 5 Refused - The name server refuses to
|
|
# perform the specified operation for
|
|
# policy reasons. For example, a name
|
|
# server may not wish to provide the
|
|
# information to the particular requester,
|
|
# or a name server may not wish to perform
|
|
# a particular operation (e.g., zone
|
|
# transfer) for particular data.
|
|
# * 6-15 Reserved for future use.
|
|
#
|
|
# In the next DNS RFCs, codes 6-15 has been assigned to the following
|
|
# errors:
|
|
#
|
|
# * 6 YXDomain
|
|
# * 7 YXRRSet
|
|
# * 8 NXRRSet
|
|
# * 9 NotAuth
|
|
# * 10 NotZone
|
|
#
|
|
# More RCodes has to come for TSIGs and other operations.
|
|
#
|
|
class RCode
|
|
|
|
# Constant for +rcode+ Response Code No Error
|
|
NOERROR = 0
|
|
# Constant for +rcode+ Response Code Format Error
|
|
FORMAT = 1
|
|
# Constant for +rcode+ Response Code Server Format Error
|
|
SERVER = 2
|
|
# Constant for +rcode+ Response Code Name Error
|
|
NAME = 3
|
|
# Constant for +rcode+ Response Code Not Implemented Error
|
|
NOTIMPLEMENTED = 4
|
|
# Constant for +rcode+ Response Code Refused Error
|
|
REFUSED = 5
|
|
|
|
|
|
|
|
RCodeType = %w[NoError FormErr ServFail NXDomain NotImp
|
|
Refused YXDomain YXRRSet NXRRSet NotAuth NotZone]
|
|
|
|
RCodeErrorString = ["No errors",
|
|
"The name server was unable to interpret the query",
|
|
"The name server was unable to process this query due to problem with the name server",
|
|
"Domain name referenced in the query does not exists",
|
|
"The name server does not support the requested kind of query",
|
|
"The name server refuses to perform the specified operation for policy reasons",
|
|
"",
|
|
"",
|
|
"",
|
|
"",
|
|
""]
|
|
|
|
attr_reader :code, :type, :explanation
|
|
|
|
def initialize(code)
|
|
if (0..10).include? code
|
|
@code = code
|
|
@type = RCodeType[code]
|
|
@explanation = RCodeErrorString[code]
|
|
else
|
|
raise HeaderArgumentError, "RCode #{code} out of range"
|
|
end
|
|
end
|
|
|
|
def to_s
|
|
@code.to_s
|
|
end
|
|
end
|
|
|
|
# Constant for +opCode+ query
|
|
QUERY = 0
|
|
# Constant for +opCode+ iquery
|
|
IQUERY = 1
|
|
# Constant for +opCode+ status
|
|
STATUS = 2
|
|
# Array with given strings
|
|
OPARR = %w[QUERY IQUERY STATUS]
|
|
|
|
@@id_arr = []
|
|
|
|
# Reader for +id+ attribute
|
|
attr_reader :id
|
|
# Reader for the operational code
|
|
attr_reader :opCode
|
|
# Reader for the rCode instance
|
|
attr_reader :rCode
|
|
# Reader for question section entries number
|
|
attr_reader :qdCount
|
|
# Reader for answer section entries number
|
|
attr_reader :anCount
|
|
# Reader for authority section entries number
|
|
attr_reader :nsCount
|
|
# Reader for addictional section entries number
|
|
attr_reader :arCount
|
|
|
|
# Creates a new Net::DNS::Header object with the desired values,
|
|
# which can be specified as an Hash argument. When called without
|
|
# arguments, defaults are used. If a data string is passed, values
|
|
# are taken from parsing the string.
|
|
#
|
|
# Examples:
|
|
#
|
|
# # Create a new Net::DNS::Header object
|
|
# header = Net::DNS::Header.new
|
|
#
|
|
# # Create a new Net::DNS::Header object passing values
|
|
# header = Net::DNS::Header.new(:opCode => 1, :rd => 0)
|
|
#
|
|
# # Create a new Net::DNS::Header object with binary data
|
|
# header = Net::DNS::Header.new(data)
|
|
#
|
|
# Default values are:
|
|
#
|
|
# :id => auto generated
|
|
# :qr => 0 # Query response flag
|
|
# :aa => 0 # Authoritative answer flag
|
|
# :tc => 0 # Truncated packet flag
|
|
# :ra => 0 # Recursiond available flag
|
|
# :rCode => 0 # Response code (status of the query)
|
|
# :opCode => 0 # Operational code (purpose of the query)
|
|
# :cd => 0 # Checking disable flag
|
|
# :ad => 0 # Only relevant in DNSSEC context
|
|
# :rd => 1 # Recursion desired flag
|
|
# :qdCount => 1 # Number of questions in the dns packet
|
|
# :anCount => 0 # Number of answer RRs in the dns packet
|
|
# :nsCount => 0 # Number of authoritative RRs in the dns packet
|
|
# :arCount => 0 # Number of additional RRs in the dns packet
|
|
#
|
|
# See also each option for a detailed explanation of usage.
|
|
#
|
|
def initialize(arg = {})
|
|
if arg.kind_of? Hash
|
|
new_from_hash(arg)
|
|
else
|
|
raise HeaderArgumentError, "Wrong argument class: #{arg.class}"
|
|
end
|
|
end
|
|
|
|
# Creates a new Net::DNS::Header object from binary data, which is
|
|
# passed as a string object as argument.
|
|
# The configurations parameters are taken from parsing the string.
|
|
#
|
|
# Example:
|
|
#
|
|
# # Create a new Net::DNS::Header object with binary data
|
|
# header = Net::DNS::Header.new(data)
|
|
#
|
|
# header.auth?
|
|
# #=> "true" if it comes from authoritative name server
|
|
#
|
|
def self.parse(arg)
|
|
if arg.kind_of? String
|
|
o = allocate
|
|
o.send(:new_from_binary, arg)
|
|
o
|
|
else
|
|
raise HeaderArgumentError, "Wrong argument class: #{arg.class}"
|
|
end
|
|
end
|
|
|
|
# Inspect method, prints out all the options and relative values.
|
|
#
|
|
# p Net::DNS::Header.new
|
|
# # ;; id = 18123
|
|
# # ;; qr = 0 opCode: 0 aa = 0 tc = 0 rd = 1
|
|
# # ;; ra = 0 ad = 0 cd = 0 rcode = 0
|
|
# # ;; qdCount = 1 anCount = 0 nsCount = 0 arCount = 0
|
|
#
|
|
# This method will maybe be changed in the future to a more pretty
|
|
# way of display output.
|
|
#
|
|
def inspect
|
|
";; id = #@id\n" +
|
|
if false # @opCode == "UPDATE"
|
|
#do stuff
|
|
else
|
|
";; qr = #@qr\t" +
|
|
"opCode: #{opCode_str}\t" +
|
|
"aa = #@aa\t" +
|
|
"tc = #@tc\t" +
|
|
"rd = #@rd\n" +
|
|
";; ra = #@ra\t" +
|
|
"ad = #@ad\t" +
|
|
"cd = #@cd\t" +
|
|
"rcode = #{@rCode.type}\n" +
|
|
";; qdCount = #@qdCount\t"+
|
|
"anCount = #@anCount\t"+
|
|
"nsCount = #@nsCount\t"+
|
|
"arCount = #@arCount\n"
|
|
end
|
|
end
|
|
|
|
# The Net::DNS::Header#format method prints out the header
|
|
# in a special ascii representation of data, in a way
|
|
# similar to those often found on RFCs.
|
|
#
|
|
# p Net::DNS::Header.new.format
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 18123 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # |0| 0 |0|0|1|0|0| 0 | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 1 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
# # | 0 |
|
|
# # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
#
|
|
# This can be very usefull for didactical purpouses :)
|
|
#
|
|
def format
|
|
del = ("+-" * 16) + "+\n"
|
|
len = del.length
|
|
str = del + "|" + @id.to_s.center(len-3) + "|\n"
|
|
str += del + "|" + @qr.to_s
|
|
str += "|" + @opCode.to_s.center(7)
|
|
str += "|" + @aa.to_s
|
|
str += "|" + @tc.to_s
|
|
str += "|" + @rd.to_s
|
|
str += "|" + @ra.to_s
|
|
str += "|" + @ad.to_s
|
|
str += "|" + @cd.to_s.center(3)
|
|
str += "|" + @rCode.to_s.center(7) + "|\n"
|
|
str += del + "|" + @qdCount.to_s.center(len-3) + "|\n"
|
|
str += del + "|" + @anCount.to_s.center(len-3) + "|\n"
|
|
str += del + "|" + @nsCount.to_s.center(len-3) + "|\n"
|
|
str += del + "|" + @arCount.to_s.center(len-3) + "|\n" + del
|
|
str
|
|
end
|
|
|
|
# Returns the header data in binary format, appropriate
|
|
# for use in a DNS query packet.
|
|
#
|
|
# hdata = header.data
|
|
# puts "Header is #{hdata.size} bytes"
|
|
#
|
|
def data
|
|
arr = []
|
|
arr.push(@id)
|
|
arr.push((@qr<<7)|(@opCode<<3)|(@aa<<2)|(@tc<<1)|@rd)
|
|
arr.push((@ra<<7)|(@ad<<5)|(@cd<<4)|@rCode.code)
|
|
arr.push(@qdCount)
|
|
arr.push(@anCount)
|
|
arr.push(@nsCount)
|
|
arr.push(@arCount)
|
|
arr.pack("n C2 n4")
|
|
end
|
|
|
|
# Set the ID for the current header. Useful when
|
|
# performing security tests.
|
|
#
|
|
def id=(val)
|
|
if @@id_arr.include? val
|
|
raise HeaderDuplicateID, "ID #{val} already used"
|
|
end
|
|
if (1..65535).include? val
|
|
@id = val
|
|
@@id_arr.push val
|
|
else
|
|
raise HeaderArgumentError, "ID #{val} out of range"
|
|
end
|
|
end
|
|
|
|
# Checks whether the header is a query (+qr+ bit set to 0)
|
|
#
|
|
def query?
|
|
@qr == 0
|
|
end
|
|
|
|
# Set the +qr+ query response flag to be either +true+ or
|
|
# +false+. You can also use the values 0 and 1. This flag
|
|
# indicates if the DNS packet contains a query or an answer,
|
|
# so it should be set to +true+ in DNS answer packets.
|
|
# If +qr+ is +true+, the packet is a response.
|
|
#
|
|
def qr=(val)
|
|
case val
|
|
when true
|
|
@qr = 1
|
|
when false
|
|
@qr = 0
|
|
when 0,1
|
|
@qr = val
|
|
else
|
|
raise HeaderArgumentError, ":qr must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Checks whether the header is a response
|
|
# (+qr+ bit set to 1)
|
|
#
|
|
def response?
|
|
@qr == 1
|
|
end
|
|
|
|
# Returns a string representation of the +opCode+
|
|
#
|
|
# puts "Packet is a #{header.opCode_str}"
|
|
# #=> Packet is a QUERY
|
|
#
|
|
def opCode_str
|
|
OPARR[@opCode]
|
|
end
|
|
|
|
# Set the +opCode+ variable to a new value. This fields indicates
|
|
# the type of the question present in the DNS packet; +val+ can be
|
|
# one of the values QUERY, IQUERY or STATUS.
|
|
#
|
|
# * QUERY is the standard DNS query
|
|
# * IQUERY is the inverse query
|
|
# * STATUS is used to query the nameserver for its status
|
|
#
|
|
# Example:
|
|
#
|
|
# include Net::DNS
|
|
# header = Header.new
|
|
# header.opCode = Header::STATUS
|
|
#
|
|
def opCode=(val)
|
|
if (0..2).include? val
|
|
@opCode = val
|
|
else
|
|
raise HeaderWrongOpcode, "Wrong opCode value (#{val}), must be QUERY, IQUERY or STATUS"
|
|
end
|
|
end
|
|
|
|
# Checks whether the response is authoritative
|
|
#
|
|
# if header.auth?
|
|
# puts "Response is authoritative"
|
|
# else
|
|
# puts "Answer is NOT authoritative"
|
|
# end
|
|
#
|
|
def auth?
|
|
@aa == 1
|
|
end
|
|
|
|
# Set the +aa+ flag (authoritative answer) to either +true+
|
|
# or +false+. You can also use 0 or 1.
|
|
#
|
|
# This flag indicates whether a DNS answer packet contains
|
|
# authoritative data, meaning that is was generated by a
|
|
# nameserver authoritative for the domain of the question.
|
|
#
|
|
# Must only be set to +true+ in DNS answer packets.
|
|
#
|
|
def aa=(val)
|
|
case val
|
|
when true
|
|
@aa = 1
|
|
when false
|
|
@aa = 0
|
|
when 0,1
|
|
@aa = val
|
|
else
|
|
raise HeaderArgumentError, ":aa must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Checks whether the packet was truncated
|
|
#
|
|
# # Sending packet using UDP
|
|
# if header.truncated?
|
|
# puts "Warning, packet has been truncated!"
|
|
# # Sending packet using TCP
|
|
# end
|
|
# # Do something with the answer
|
|
#
|
|
def truncated?
|
|
@tc == 1
|
|
end
|
|
|
|
# Set the +tc+ flag (truncated packet) to either +true+
|
|
# ot +false+. You can also use 0 or 1.
|
|
#
|
|
# The truncated flag is used in response packets to indicate
|
|
# that the amount of data to be trasmitted exceedes the
|
|
# maximum allowed by the protocol in use, tipically UDP, and
|
|
# that the data present in the packet has been truncated.
|
|
# A different protocol (such has TCP) need to be used to
|
|
# retrieve full data.
|
|
#
|
|
# Must only be set in DNS answer packets.
|
|
#
|
|
def tc=(val)
|
|
case val
|
|
when true
|
|
@tc = 1
|
|
when false
|
|
@tc = 0
|
|
when 0,1
|
|
@tc = val
|
|
else
|
|
raise HeaderArgumentError, ":tc must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Checks whether the packet has a recursion bit
|
|
# set, meaning that recursion is desired
|
|
#
|
|
def recursive?
|
|
@rd == 1
|
|
end
|
|
|
|
# Sets the recursion desidered bit.
|
|
# Remember that recursion query support is
|
|
# optional.
|
|
#
|
|
# header.recursive = true
|
|
# hdata = header.data # suitable for sending
|
|
#
|
|
# Consult RFC1034 and RFC1035 for a detailed explanation
|
|
# of how recursion works.
|
|
#
|
|
def recursive=(val)
|
|
case val
|
|
when true
|
|
@rd = 1
|
|
when false
|
|
@rd = 0
|
|
when 1
|
|
@rd = 1
|
|
when 0
|
|
@rd = 0
|
|
else
|
|
raise HeaderWrongRecursive, "Wrong value (#{val}), please specify true (1) or false (0)"
|
|
end
|
|
end
|
|
|
|
# Alias for Header#recursive= to keep compatibility
|
|
# with the Perl version.
|
|
#
|
|
def rd=(val)
|
|
self.recursive = val
|
|
end
|
|
|
|
# Checks whether recursion is available.
|
|
# This flag is usually set by nameservers to indicate
|
|
# that they support recursive-type queries.
|
|
#
|
|
def r_available?
|
|
@ra == 1
|
|
end
|
|
|
|
# Set the +ra+ flag (recursion available) to either +true+ or
|
|
# +false+. You can also use 0 and 1.
|
|
#
|
|
# This flag must only be set in DNS answer packets.
|
|
#
|
|
def ra=(val)
|
|
case val
|
|
when true
|
|
@ra = 1
|
|
when false
|
|
@ra = 0
|
|
when 0,1
|
|
@ra = val
|
|
else
|
|
raise HeaderArgumentError, ":ra must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Checks whether checking is enabled or disabled.
|
|
#
|
|
# Checking is enabled by default.
|
|
#
|
|
def checking?
|
|
@cd == 0
|
|
end
|
|
|
|
# Set the +cd+ flag (checking disabled) to either +true+
|
|
# ot +false+. You can also use 0 or 1.
|
|
#
|
|
def cd=(val)
|
|
case val
|
|
when true
|
|
@cd = 1
|
|
when false
|
|
@cd = 0
|
|
when 0,1
|
|
@cd = val
|
|
else
|
|
raise HeaderArgumentError, ":cd must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Checks whether +ad+ flag has been set.
|
|
#
|
|
# This flag is only relevant in DNSSEC context.
|
|
#
|
|
def verified?
|
|
@ad == 1
|
|
end
|
|
|
|
# Set the +ad+ flag to either +true+
|
|
# ot +false+. You can also use 0 or 1.
|
|
#
|
|
# The AD bit is only set on answers where signatures have
|
|
# been cryptographically verified or the server is
|
|
# authoritative for the data and is allowed to set the bit by policy.
|
|
#
|
|
def ad=(val)
|
|
case val
|
|
when true
|
|
@ad = 1
|
|
when false
|
|
@ad = 0
|
|
when 0,1
|
|
@ad = val
|
|
else
|
|
raise HeaderArgumentError, ":ad must be true(or 1) or false(or 0)"
|
|
end
|
|
end
|
|
|
|
# Returns an error array for the header response code, or
|
|
# +nil+ if no error is generated.
|
|
#
|
|
# error, cause = header.rCode_str
|
|
# puts "Error #{error} cause by: #{cause}" if error
|
|
# #=> Error ForErr caused by: The name server
|
|
# #=> was unable to interpret the query
|
|
#
|
|
def rCode_str
|
|
return rCode.type, rCode.explanation
|
|
end
|
|
|
|
# Checks for errors in the DNS packet
|
|
#
|
|
# unless header.error?
|
|
# puts "No errors in DNS answer packet"
|
|
# end
|
|
#
|
|
def error?
|
|
@rCode.code > 0
|
|
end
|
|
|
|
# Set the rCode value. This should only be done in DNS
|
|
# answer packets.
|
|
#
|
|
def rCode=(val)
|
|
@rCode = RCode.new(val)
|
|
end
|
|
|
|
# Sets the number of entries in a question section
|
|
#
|
|
def qdCount=(val)
|
|
if (0..65535).include? val
|
|
@qdCount = val
|
|
else
|
|
raise HeaderWrongCount, "Wrong number of count (#{val}), must be 0-65535"
|
|
end
|
|
end
|
|
|
|
# Sets the number of RRs in an answer section
|
|
#
|
|
def anCount=(val)
|
|
if (0..65535).include? val
|
|
@anCount = val
|
|
else
|
|
raise HeaderWrongCount, "Wrong number of count (#{val}), must be 0-65535"
|
|
end
|
|
end
|
|
|
|
# Sets the number of RRs in an authority section
|
|
#
|
|
def nsCount=(val)
|
|
if (0..65535).include? val
|
|
@nsCount = val
|
|
else
|
|
raise HeaderWrongCount, "Wrong number of count (#{val}), must be 0-65535"
|
|
end
|
|
end
|
|
|
|
# Sets the number of RRs in an addictional section
|
|
#
|
|
def arCount=(val)
|
|
if (0..65535).include? val
|
|
@arCount = val
|
|
else
|
|
raise HeaderWrongCount, "Wrong number of count (#{val}), must be 0-65535"
|
|
end
|
|
end
|
|
|
|
private
|
|
|
|
def new_from_scratch
|
|
@id = genID # generate ad unique id
|
|
@qr = @aa = @tc = @ra = @ad = @cd = 0
|
|
@rCode = RCode.new(0) # no error
|
|
@anCount = @nsCount = @arCount = 0
|
|
@rd = @qdCount = 1
|
|
@opCode = QUERY # standard query, default message
|
|
end
|
|
|
|
def new_from_binary(str)
|
|
unless str.size == Net::DNS::HFIXEDSZ
|
|
raise HeaderArgumentError, "Header binary data has wrong size: #{str.size} bytes"
|
|
end
|
|
arr = str.unpack("n C2 n4")
|
|
@id = arr[0]
|
|
@qr = (arr[1] >> 7) & 0x01
|
|
@opCode = (arr[1] >> 3) & 0x0F
|
|
@aa = (arr[1] >> 2) & 0x01
|
|
@tc = (arr[1] >> 1) & 0x01
|
|
@rd = arr[1] & 0x1
|
|
@ra = (arr[2] >> 7) & 0x01
|
|
@ad = (arr[2] >> 5) & 0x01
|
|
@cd = (arr[2] >> 4) & 0x01
|
|
@rCode = RCode.new(arr[2] & 0xf)
|
|
@qdCount = arr[3]
|
|
@anCount = arr[4]
|
|
@nsCount = arr[5]
|
|
@arCount = arr[6]
|
|
end
|
|
|
|
def new_from_hash(hash)
|
|
new_from_scratch
|
|
hash.each do |key,val|
|
|
eval "self.#{key.to_s} = val"
|
|
end
|
|
end
|
|
|
|
def genID
|
|
while (@@id_arr.include?(q = rand(65535)))
|
|
end
|
|
@@id_arr.push(q)
|
|
q
|
|
end
|
|
|
|
end # class Header
|
|
|
|
end # class DNS
|
|
end # module Net
|
|
|
|
|
|
class HeaderArgumentError < ArgumentError # :nodoc: all
|
|
end
|
|
|
|
class HeaderWrongCount < ArgumentError # :nodoc: all
|
|
end
|
|
|
|
class HeaderWrongRecursive < ArgumentError # :nodoc: all
|
|
end
|
|
|
|
class HeaderWrongOpcode < ArgumentError # :nodoc: all
|
|
end
|
|
|
|
class HeaderDuplicateID < ArgumentError # :nodoc: all
|
|
end
|