PacketFu::TCPHeader

TCPHeader is a complete TCP struct, used in TCPPacket. Most IP traffic is TCP-based, by volume.

For more on TCP packets, see www.networksorcery.com/enp/protocol/tcp.htm

Header Definition

  Int16        :tcp_src       Default: random
  Int16        :tcp_dst
  Int32        :tcp_seq       Default: random
  Int32        :tcp_ack
  TcpHlen      :tcp_hlen      Default: 5           # Must recalc as options are set.
  TcpReserved  :tcp_reserved  Default: 0
  TcpEcn       :tcp_ecn
  TcpFlags     :tcp_flags
  Int16        :tcp_win,      Default: 0           # WinXP's default syn packet
  Int16        :tcp_sum,      Default: calculated  # Must set this upon generation.
  Int16        :tcp_urg
  TcpOptions   :tcp_opts
  String       :body

See also TcpHlen, TcpReserved, TcpEcn, TcpFlags, TcpOpts

Methods

B

bits_to_s

N

R

rand_port,
read

T

tcp_ack,
tcp_ack=,
tcp_ack_readable,
tcp_calc_hlen,
tcp_calc_seq,
tcp_calc_src,
tcp_dport,
tcp_dport=,
tcp_dst,
tcp_dst=,
tcp_ecn,
tcp_ecn=,
tcp_flags_dotmap,
tcp_flags_readable,
tcp_hlen,
tcp_hlen=,
tcp_options,
tcp_options=,
tcp_opts,
tcp_opts=,
tcp_opts_len,
tcp_opts_readable,
tcp_recalc,
tcp_reserved,
tcp_reserved=,
tcp_seq,
tcp_seq=,
tcp_seq_readable,
tcp_sport,
tcp_sport=,
tcp_src,
tcp_src=,
tcp_sum,
tcp_sum=,
tcp_sum_readable,
tcp_urg,
tcp_urg=,
tcp_win,
tcp_win=,
to_s

Included Modules

PacketFu START:includes

Attributes

[RW]

flavor

Class Public methods

new(args={})

Source: show

# File lib/packetfu/protos/tcp.rb, line 670
                def initialize(args={})
                        @random_seq = rand(0xffffffff)
                        @random_src = rand_port
                        super(
                                Int16.new(args[:tcp_src] || tcp_calc_src),
                                Int16.new(args[:tcp_dst]),
                                Int32.new(args[:tcp_seq] || tcp_calc_seq),
                                Int32.new(args[:tcp_ack]),
                                TcpHlen.new(:hlen => (args[:tcp_hlen] || 5)),
                                TcpReserved.new(args[:tcp_reserved] || 0),
                                TcpEcn.new(args[:tcp_ecn]),
                                TcpFlags.new(args[:tcp_flags]),
                                Int16.new(args[:tcp_win] || 0x4000),
                                Int16.new(args[:tcp_sum] || 0),
                                Int16.new(args[:tcp_urg]),
                                TcpOptions.new.read(args[:tcp_opts]),
                                StructFu::String.new.read(args[:body])
                        )
                end

Instance Public methods

bits_to_s()

Helper function to create the string for Hlen, Reserved, ECN, and Flags.

Source: show

# File lib/packetfu/protos/tcp.rb, line 693
                def bits_to_s
                        bytes = []
                        bytes[0] = (self[:tcp_hlen].to_i << 4) +
                                (self[:tcp_reserved].to_i << 1) +
                                self[:tcp_ecn].n.to_i
                        bytes[1] = (self[:tcp_ecn].c.to_i << 7) +
                                (self[:tcp_ecn].e.to_i << 6) +
                                self[:tcp_flags].to_i
                        bytes.pack("CC")
                end

rand_port()

Generates a random high port. This is affected by packet flavor.

Source: show

# File lib/packetfu/protos/tcp.rb, line 852
                def rand_port
                        rand(0xffff - 1025) + 1025
                end

read(str)

Reads a string to populate the object.

Source: show

# File lib/packetfu/protos/tcp.rb, line 723
                def read(str)
                        force_binary(str)
                        return self if str.nil?
                        self[:tcp_src].read(str[0,2])
                        self[:tcp_dst].read(str[2,2])
                        self[:tcp_seq].read(str[4,4])
                        self[:tcp_ack].read(str[8,4])
                        self[:tcp_hlen].read(str[12,1])
                        self[:tcp_reserved].read(str[12,1])
                        self[:tcp_ecn].read(str[12,2])
                        self[:tcp_flags].read(str[13,1])
                        self[:tcp_win].read(str[14,2])
                        self[:tcp_sum].read(str[16,2])
                        self[:tcp_urg].read(str[18,2])
                        self[:tcp_opts].read(str[20,((self[:tcp_hlen].to_i * 4) - 20)])
                        self[:body].read(str[(self[:tcp_hlen].to_i * 4),str.size])
                        self
                end

tcp_ack()

Getter for the TCP ackowlegement number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 757
                def tcp_ack; self[:tcp_ack].to_i; end

tcp_ack=(i)

Setter for the TCP ackowlegement number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 755
                def tcp_ack=(i); typecast i; end

tcp_ack_readable()

Source: show

# File lib/packetfu/protos/tcp.rb, line 919
                def tcp_ack_readable
                        "0x%08x" % tcp_ack
                end

tcp_calc_hlen()

Sets and returns the true length of the TCP Header. TODO: Think about making all the option stuff safer.

Source: show

# File lib/packetfu/protos/tcp.rb, line 847
                def tcp_calc_hlen
                        self[:tcp_hlen] = TcpHlen.new(:hlen => ((20 + tcp_opts_len) / 4))
                end

tcp_calc_seq()

Resets the sequence number to a new random number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 836
                def tcp_calc_seq; @random_seq; end

tcp_calc_src()

Resets the source port to a new random number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 838
                def tcp_calc_src; @random_src; end

tcp_dport()

Equivalent to tcp_dst.

Source: show

# File lib/packetfu/protos/tcp.rb, line 886
                def tcp_dport
                        self.tcp_dst.to_i
                end

tcp_dport=(arg)

Equivalent to tcp_dst=.

Source: show

# File lib/packetfu/protos/tcp.rb, line 891
                def tcp_dport=(arg)
                        self.tcp_dst=(arg)
                end

tcp_dst()

Getter for the TCP destination port.

Source: show

# File lib/packetfu/protos/tcp.rb, line 749
                def tcp_dst; self[:tcp_dst].to_i; end

tcp_dst=(i)

Setter for the TCP destination port.

Source: show

# File lib/packetfu/protos/tcp.rb, line 747
                def tcp_dst=(i); typecast i; end

tcp_ecn()

Getter for the ECN bits.

Source: show

# File lib/packetfu/protos/tcp.rb, line 806
                def tcp_ecn; self[:tcp_ecn].to_i; end

tcp_ecn=(i)

Setter for the ECN bits.

Source: show

# File lib/packetfu/protos/tcp.rb, line 808
                def tcp_ecn=(i)
                        case i
                        when PacketFu::TcpEcn
                                self[:tcp_ecn]=i
                        when Numeric
                                args = {}
                                args[:n] = (i & 0b100) >> 2
                                args[:c] = (i & 0b010) >> 1
                                args[:e] = (i & 0b001)
                                self[:tcp_ecn] = TcpEcn.new(args)
                        else
                                self[:tcp_ecn].read(i)
                        end
                end

tcp_flags_dotmap()

Gets a more readable flags list

This method is also aliased as tcp_flags_readable

Source: show

# File lib/packetfu/protos/tcp.rb, line 862
                def tcp_flags_dotmap
                        dotmap = tcp_flags.members.map do |flag|
                                status = self.tcp_flags.send flag
                                status == 0 ? "." : flag.to_s.upcase[0].chr
                        end
                        dotmap.join
                end

tcp_flags_readable()

Alias for tcp_flags_dotmap

tcp_hlen()

Getter for the TCP Header Length value.

Source: show

# File lib/packetfu/protos/tcp.rb, line 772
                def tcp_hlen; self[:tcp_hlen].to_i; end

tcp_hlen=(i)

Setter for the TCP Header Length value. Can take either a string or an integer. Note that if it’s a string, the top four bits are used.

Source: show

# File lib/packetfu/protos/tcp.rb, line 776
                def tcp_hlen=(i)
                        case i
                        when PacketFu::TcpHlen
                                self[:tcp_hlen] = i
                        when Numeric
                                self[:tcp_hlen] = TcpHlen.new(:hlen => i.to_i)
                        else
                                self[:tcp_hlen].read(i)
                        end
                end

tcp_options()

Gets a more readable option list.

Source: show

# File lib/packetfu/protos/tcp.rb, line 857
                def tcp_options
                 self[:tcp_opts].decode
                end

tcp_options=(arg)

Sets a more readable option list.

Source: show

# File lib/packetfu/protos/tcp.rb, line 871
                def tcp_options=(arg)
                        self[:tcp_opts].encode arg
                end

tcp_opts()

Getter for TCP Options.

Source: show

# File lib/packetfu/protos/tcp.rb, line 824
                def tcp_opts; self[:tcp_opts].to_s; end

tcp_opts=(i)

Setter for TCP Options.

Source: show

# File lib/packetfu/protos/tcp.rb, line 826
                def tcp_opts=(i)
                        case i
                        when PacketFu::TcpOptions
                                self[:tcp_opts]=i
                        else
                                self[:tcp_opts].read(i)
                        end
                end

tcp_opts_len()

Returns the actual length of the TCP options.

Source: show

# File lib/packetfu/protos/tcp.rb, line 841
                def tcp_opts_len
                        self[:tcp_opts].to_s.size
                end

tcp_opts_readable()

Source: show

# File lib/packetfu/protos/tcp.rb, line 931
                def tcp_opts_readable
                        tcp_options
                end

tcp_recalc(arg=:all)

Recalculates calculated fields for TCP (except checksum which is at the Packet level).

Source: show

# File lib/packetfu/protos/tcp.rb, line 896
                def tcp_recalc(arg=:all)
                        case arg
                        when :tcp_hlen
                                tcp_calc_hlen
                        when :tcp_src
                                @random_tcp_src = rand_port
                        when :tcp_sport
                                @random_tcp_src = rand_port
                        when :tcp_seq
                                @random_tcp_seq = rand(0xffffffff) 
                        when :all
                                tcp_calc_hlen
                                @random_tcp_src = rand_port
                                @random_tcp_seq = rand(0xffffffff) 
                        else
                                raise ArgumentError, "No such field `#{arg}'"
                        end
                end

tcp_reserved()

Getter for the TCP Reserved field.

Source: show

# File lib/packetfu/protos/tcp.rb, line 788
                def tcp_reserved; self[:tcp_reserved].to_i; end

tcp_reserved=(i)

Setter for the TCP Reserved field.

Source: show

# File lib/packetfu/protos/tcp.rb, line 790
                def tcp_reserved=(i)
                        case i
                        when PacketFu::TcpReserved
                                self[:tcp_reserved]=i
                        when Numeric
                                args = {}
                                args[:r1] = (i & 0b100) >> 2
                                args[:r2] = (i & 0b010) >> 1
                                args[:r3] = (i & 0b001)
                                self[:tcp_reserved] = TcpReserved.new(args)
                        else
                                self[:tcp_reserved].read(i)
                        end
                end

tcp_seq()

Getter for the TCP sequence number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 753
                def tcp_seq; self[:tcp_seq].to_i; end

tcp_seq=(i)

Setter for the TCP sequence number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 751
                def tcp_seq=(i); typecast i; end

tcp_seq_readable()

Source: show

# File lib/packetfu/protos/tcp.rb, line 923
                def tcp_seq_readable
                        "0x%08x" % tcp_seq
                end

tcp_sport()

Equivalent to tcp_src.

Source: show

# File lib/packetfu/protos/tcp.rb, line 876
                def tcp_sport
                        self.tcp_src.to_i
                end

tcp_sport=(arg)

Equivalent to tcp_src=.

Source: show

# File lib/packetfu/protos/tcp.rb, line 881
                def tcp_sport=(arg)
                        self.tcp_src=(arg)
                end

tcp_src()

Getter for the TCP source port.

Source: show

# File lib/packetfu/protos/tcp.rb, line 745
                def tcp_src; self[:tcp_src].to_i; end

tcp_src=(i)

Setter for the TCP source port.

Source: show

# File lib/packetfu/protos/tcp.rb, line 743
                def tcp_src=(i); typecast i; end

tcp_sum()

Getter for the TCP checksum.

Source: show

# File lib/packetfu/protos/tcp.rb, line 765
                def tcp_sum; self[:tcp_sum].to_i; end

tcp_sum=(i)

Setter for the TCP checksum.

Source: show

# File lib/packetfu/protos/tcp.rb, line 763
                def tcp_sum=(i); typecast i; end

tcp_sum_readable()

Source: show

# File lib/packetfu/protos/tcp.rb, line 927
                def tcp_sum_readable
                        "0x%04x" % tcp_sum
                end

tcp_urg()

Getter for the TCP urgent field.

Source: show

# File lib/packetfu/protos/tcp.rb, line 769
                def tcp_urg; self[:tcp_urg].to_i; end

tcp_urg=(i)

Setter for the TCP urgent field.

Source: show

# File lib/packetfu/protos/tcp.rb, line 767
                def tcp_urg=(i); typecast i; end

tcp_win()

Getter for the TCP window size number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 761
                def tcp_win; self[:tcp_win].to_i; end

tcp_win=(i)

Setter for the TCP window size number.

Source: show

# File lib/packetfu/protos/tcp.rb, line 759
                def tcp_win=(i); typecast i; end

to_s()

Returns the object in string form.

Source: show

# File lib/packetfu/protos/tcp.rb, line 705
                def to_s
                        hdr = self.to_a.map do |x|
                                if x.kind_of? TcpHlen
                                        bits_to_s
                                elsif x.kind_of? TcpReserved
                                        next
                                elsif x.kind_of? TcpEcn
                                        next
                                elsif x.kind_of? TcpFlags
                                        next
                                else
                                        x.to_s
                                end
                        end
                        hdr.flatten.join
                end

Class PacketFu::TCPHeader < Struct.new(:tcp_src, :tcp_dst, :tcp_seq, :tcp_ack, :tcp_hlen, :tcp_reserved, :tcp_ecn, :tcp_flags, :tcp_win, :tcp_sum, :tcp_urg, :tcp_opts, :body)

Header Definition