UDP is a simple stateless transport layer (AKA OSI layer 4) protocol, one of the core Internet protocols. It provides source and destination ports, basic checksumming, but provides not guarantees of delivery, order of packets, or duplicate delivery.
This page hosts a formal specification of UDP (User Datagram Protocol) datagram using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.
The Ruby runtime library can be installed from RubyGems:
gem install kaitai-structParse a local file and get structure in memory:
data = UdpDatagram.from_file("path/to/local/file.bin")
Or parse structure from a string of bytes:
bytes = "\x00\x01\x02..."
data = UdpDatagram.new(Kaitai::Struct::Stream.new(bytes))
After that, one can get various attributes from the structure by invoking getter methods like:
data.src_port # => get src port
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
require 'kaitai/struct/struct'
unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end
##
# UDP is a simple stateless transport layer (AKA OSI layer 4)
# protocol, one of the core Internet protocols. It provides source and
# destination ports, basic checksumming, but provides not guarantees
# of delivery, order of packets, or duplicate delivery.
class UdpDatagram < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@src_port = @_io.read_u2be
@dst_port = @_io.read_u2be
@length = @_io.read_u2be
@checksum = @_io.read_u2be
@body = @_io.read_bytes((length - 8))
self
end
attr_reader :src_port
attr_reader :dst_port
attr_reader :length
attr_reader :checksum
attr_reader :body
end