### Home Classes Methods

### In Files

- lib/packetfu/protos/tcp/header.rb

### Parent

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)

### Methods

- ::new
- #bits_to_s
- #rand_port
- #read
- #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

- StructFu

### Files

- .document
- README.rdoc

### Class/Module Index

Quicksearch

- PacketFu
- PacketFu::ARPHeader
- PacketFu::ARPHeaderMixin
- PacketFu::ARPPacket
- PacketFu::AddrIpv6
- PacketFu::Capture
- PacketFu::Config
- PacketFu::EthHeader
- PacketFu::EthHeaderMixin
- PacketFu::EthMac
- PacketFu::EthNic
- PacketFu::EthOui
- PacketFu::EthPacket
- PacketFu::HSRPHeader
- PacketFu::HSRPHeaderMixin
- PacketFu::HSRPPacket
- PacketFu::ICMPHeader
- PacketFu::ICMPHeaderMixin
- PacketFu::ICMPPacket
- PacketFu::IPHeader
- PacketFu::IPHeaderMixin
- PacketFu::IPPacket
- PacketFu::IPv6Header
- PacketFu::IPv6HeaderMixin
- PacketFu::IPv6Packet
- PacketFu::Inject
- PacketFu::InvalidHeader
- PacketFu::InvalidPacket
- PacketFu::LLDPHeader
- PacketFu::LLDPHeaderMixin
- PacketFu::LLDPPacket
- PacketFu::Octets
- PacketFu::Packet
- PacketFu::PcapFile
- PacketFu::PcapHeader
- PacketFu::PcapPacket
- PacketFu::PcapPackets
- PacketFu::Read
- PacketFu::TCPHeader
- PacketFu::TCPHeaderMixin
- PacketFu::TCPPacket
- PacketFu::TcpEcn
- PacketFu::TcpFlags
- PacketFu::TcpHlen
- PacketFu::TcpOption
- PacketFu::TcpOption::ECHO
- PacketFu::TcpOption::ECHOREPLY
- PacketFu::TcpOption::EOL
- PacketFu::TcpOption::MSS
- PacketFu::TcpOption::NOP
- PacketFu::TcpOption::SACK
- PacketFu::TcpOption::SACKOK
- PacketFu::TcpOption::TS
- PacketFu::TcpOption::WS
- PacketFu::TcpOptions
- PacketFu::TcpReserved
- PacketFu::Timestamp
- PacketFu::UDPHeader
- PacketFu::UDPHeaderMixin
- PacketFu::UDPPacket
- PacketFu::Utils
- PacketFu::Write
- StructFu
- StructFu::Int
- StructFu::Int16
- StructFu::Int16be
- StructFu::Int16le
- StructFu::Int32
- StructFu::Int32be
- StructFu::Int32le
- StructFu::Int8
- StructFu::IntString
- StructFu::String
- Struct

No matching classes.

# 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

### Attributes

flavor[RW]

### Public Class Methods

new(args={}) click to toggle source

    # File lib/packetfu/protos/tcp/header.rb, line 40
    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

### Public Instance Methods

bits_to_s() click to toggle source

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

    # File lib/packetfu/protos/tcp/header.rb, line 63
    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() click to toggle source

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

    # File lib/packetfu/protos/tcp/header.rb, line 222
    def rand_port
      rand(0xffff - 1025) + 1025
    end

read(str) click to toggle source

Reads a string to populate the object.

    # File lib/packetfu/protos/tcp/header.rb, line 93
    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() click to toggle source

Getter for the TCP ackowlegement number.

    # File lib/packetfu/protos/tcp/header.rb, line 127
    def tcp_ack; self[:tcp_ack].to_i; end

tcp_ack=(i) click to toggle source

Setter for the TCP ackowlegement number.

    # File lib/packetfu/protos/tcp/header.rb, line 125
    def tcp_ack=(i); typecast i; end

tcp_ack_readable() click to toggle source

    # File lib/packetfu/protos/tcp/header.rb, line 289
    def tcp_ack_readable
      "0x%08x" % tcp_ack
    end

tcp_calc_hlen() click to toggle source

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

    # File lib/packetfu/protos/tcp/header.rb, line 217
    def tcp_calc_hlen
      self[:tcp_hlen] = TcpHlen.new(:hlen => ((20 + tcp_opts_len) / 4))
    end

tcp_calc_seq() click to toggle source

Resets the sequence number to a new random number.

    # File lib/packetfu/protos/tcp/header.rb, line 206
    def tcp_calc_seq; @random_seq; end

tcp_calc_src() click to toggle source

Resets the source port to a new random number.

    # File lib/packetfu/protos/tcp/header.rb, line 208
    def tcp_calc_src; @random_src; end

tcp_dport() click to toggle source

Equivalent to tcp_dst.

    # File lib/packetfu/protos/tcp/header.rb, line 256
    def tcp_dport
      self.tcp_dst.to_i
    end

tcp_dport=(arg) click to toggle source

Equivalent to tcp_dst=.

    # File lib/packetfu/protos/tcp/header.rb, line 261
    def tcp_dport=(arg)
      self.tcp_dst=(arg)
    end

tcp_dst() click to toggle source

Getter for the TCP destination port.

    # File lib/packetfu/protos/tcp/header.rb, line 119
    def tcp_dst; self[:tcp_dst].to_i; end

tcp_dst=(i) click to toggle source

Setter for the TCP destination port.

    # File lib/packetfu/protos/tcp/header.rb, line 117
    def tcp_dst=(i); typecast i; end

tcp_ecn() click to toggle source

Getter for the ECN bits.

    # File lib/packetfu/protos/tcp/header.rb, line 176
    def tcp_ecn; self[:tcp_ecn].to_i; end

tcp_ecn=(i) click to toggle source

Setter for the ECN bits.

    # File lib/packetfu/protos/tcp/header.rb, line 178
    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() click to toggle source

Gets a more readable flags list

    # File lib/packetfu/protos/tcp/header.rb, line 232
    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

Also aliased as: tcp_flags_readable
tcp_flags_readable() click to toggle source

Readability aliases

Alias for: tcp_flags_dotmap
tcp_hlen() click to toggle source

Getter for the TCP Header Length value.

    # File lib/packetfu/protos/tcp/header.rb, line 142
    def tcp_hlen; self[:tcp_hlen].to_i; end

tcp_hlen=(i) click to toggle source

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.

    # File lib/packetfu/protos/tcp/header.rb, line 146
    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() click to toggle source

Gets a more readable option list.

    # File lib/packetfu/protos/tcp/header.rb, line 227
    def tcp_options
     self[:tcp_opts].decode
    end

tcp_options=(arg) click to toggle source

Sets a more readable option list.

    # File lib/packetfu/protos/tcp/header.rb, line 241
    def tcp_options=(arg)
      self[:tcp_opts].encode arg
    end

tcp_opts() click to toggle source

Getter for TCP Options.

    # File lib/packetfu/protos/tcp/header.rb, line 194
    def tcp_opts; self[:tcp_opts].to_s; end

tcp_opts=(i) click to toggle source

Setter for TCP Options.

    # File lib/packetfu/protos/tcp/header.rb, line 196
    def tcp_opts=(i)
      case i
      when PacketFu::TcpOptions
        self[:tcp_opts]=i
      else
        self[:tcp_opts].read(i)
      end
    end

tcp_opts_len() click to toggle source

Returns the actual length of the TCP options.

    # File lib/packetfu/protos/tcp/header.rb, line 211
    def tcp_opts_len
      self[:tcp_opts].to_s.size
    end

tcp_opts_readable() click to toggle source

    # File lib/packetfu/protos/tcp/header.rb, line 301
    def tcp_opts_readable
      tcp_options
    end

tcp_recalc(arg=:all) click to toggle source

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

    # File lib/packetfu/protos/tcp/header.rb, line 266
    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() click to toggle source

Getter for the TCP Reserved field.

    # File lib/packetfu/protos/tcp/header.rb, line 158
    def tcp_reserved; self[:tcp_reserved].to_i; end

tcp_reserved=(i) click to toggle source

Setter for the TCP Reserved field.

    # File lib/packetfu/protos/tcp/header.rb, line 160
    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() click to toggle source

Getter for the TCP sequence number.

    # File lib/packetfu/protos/tcp/header.rb, line 123
    def tcp_seq; self[:tcp_seq].to_i; end

tcp_seq=(i) click to toggle source

Setter for the TCP sequence number.

    # File lib/packetfu/protos/tcp/header.rb, line 121
    def tcp_seq=(i); typecast i; end

tcp_seq_readable() click to toggle source

    # File lib/packetfu/protos/tcp/header.rb, line 293
    def tcp_seq_readable
      "0x%08x" % tcp_seq
    end

tcp_sport() click to toggle source

Equivalent to tcp_src.

    # File lib/packetfu/protos/tcp/header.rb, line 246
    def tcp_sport
      self.tcp_src.to_i
    end

tcp_sport=(arg) click to toggle source

Equivalent to tcp_src=.

    # File lib/packetfu/protos/tcp/header.rb, line 251
    def tcp_sport=(arg)
      self.tcp_src=(arg)
    end

tcp_src() click to toggle source

Getter for the TCP source port.

    # File lib/packetfu/protos/tcp/header.rb, line 115
    def tcp_src; self[:tcp_src].to_i; end

tcp_src=(i) click to toggle source

Setter for the TCP source port.

    # File lib/packetfu/protos/tcp/header.rb, line 113
    def tcp_src=(i); typecast i; end

tcp_sum() click to toggle source

Getter for the TCP checksum.

    # File lib/packetfu/protos/tcp/header.rb, line 135
    def tcp_sum; self[:tcp_sum].to_i; end

tcp_sum=(i) click to toggle source

Setter for the TCP checksum.

    # File lib/packetfu/protos/tcp/header.rb, line 133
    def tcp_sum=(i); typecast i; end

tcp_sum_readable() click to toggle source

    # File lib/packetfu/protos/tcp/header.rb, line 297
    def tcp_sum_readable
      "0x%04x" % tcp_sum
    end

tcp_urg() click to toggle source

Getter for the TCP urgent field.

    # File lib/packetfu/protos/tcp/header.rb, line 139
    def tcp_urg; self[:tcp_urg].to_i; end

tcp_urg=(i) click to toggle source

Setter for the TCP urgent field.

    # File lib/packetfu/protos/tcp/header.rb, line 137
    def tcp_urg=(i); typecast i; end

tcp_win() click to toggle source

Getter for the TCP window size number.

    # File lib/packetfu/protos/tcp/header.rb, line 131
    def tcp_win; self[:tcp_win].to_i; end

tcp_win=(i) click to toggle source

Setter for the TCP window size number.

    # File lib/packetfu/protos/tcp/header.rb, line 129
    def tcp_win=(i); typecast i; end

to_s() click to toggle source

Returns the object in string form.

    # File lib/packetfu/protos/tcp/header.rb, line 75
    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

[Validate]

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