152 lines
4.1 KiB
Ruby
152 lines
4.1 KiB
Ruby
require 'netlink/constants'
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module Netlink
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# Base class for Netlink messages
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class Message
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# Map of numeric message type code => message class
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CODE_TO_MESSAGE = {}
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# You can initialize a message from a Hash or from another
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# instance of itself.
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#
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# class Foo < Message
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# field :foo, "C", 0xff
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# field :bar, "L", 0
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# end
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# msg = Foo.new(:bar => 123) # or ("bar" => 123)
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# msg2 = Foo.new(msg)
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# msg3 = Foo.new(:qux => 999) # error, no method qux=
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def initialize(h={})
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if h.instance_of?(self.class)
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@attrs = h.to_hash.dup
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else
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@attrs = self.class::DEFAULTS.dup
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h.each { |k,v| self[k] = v }
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end
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end
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def to_hash
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@attrs
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end
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def each(&blk)
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@attrs.each(&blk)
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end
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# Set a field by name. Can use either symbol or string as key.
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def []=(k,v)
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send "#{k}=", v
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end
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# Retrieve a field by name. Must use symbol as key.
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def [](k)
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@attrs[k]
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end
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def self.inherited(subclass) #:nodoc:
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subclass.const_set(:FIELDS, [])
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subclass.const_set(:FORMAT, "")
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subclass.const_set(:DEFAULTS, {})
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end
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# Define which message type code(s) use this structure
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def self.code(*codes)
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codes.each { |code| CODE_TO_MESSAGE[code] = self }
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end
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# Define a field for this message, which creates accessor methods. The
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# "pattern" is the Array#pack or String#unpack code to extract this field.
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def self.field(name, pattern, default=nil, opt={})
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self::FIELDS << name
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self::FORMAT << pattern
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self::DEFAULTS[name] = default
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define_method name do
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@attrs.fetch name
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end
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define_method "#{name}=" do |val|
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@attrs.store name, val
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end
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end
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def self.uchar(name, *args); field name, "C", 0, *args; end
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def self.uint16(name, *args); field name, "S", 0, *args; end
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def self.uint32(name, *args); field name, "L", 0, *args; end
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def self.char(name, *args); field name, "c", 0, *args; end
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def self.int16(name, *args); field name, "s", 0, *args; end
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def self.int32(name, *args); field name, "l", 0, *args; end
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def self.ushort(name, *args); field name, "S_", 0, *args; end
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def self.uint(name, *args); field name, "I", 0, *args; end
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def self.ulong(name, *args); field name, "L_", 0, *args; end
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def self.short(name, *args); field name, "s_", 0, *args; end
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def self.int(name, *args); field name, "i", 0, *args; end
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def self.long(name, *args); field name, "l_", 0, *args; end
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# Returns the packed binary representation of this message (without
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# header, and not padded to NLMSG_ALIGNTO bytes)
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def to_s
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self.class::FIELDS.map { |key| self[key] }.pack(self.class::FORMAT)
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end
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def inspect
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"#<#{self.class} #{@attrs.inspect}>"
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end
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# Convert a binary representation of this message into an object instance
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def self.parse(str)
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res = new
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str.unpack(self::FORMAT).zip(self::FIELDS).each do |val, key|
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res[key] = val
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end
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res
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end
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NLMSG_ALIGNTO_1 = NLMSG_ALIGNTO-1 #:nodoc:
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NLMSG_ALIGNTO_1_MASK = ~NLMSG_ALIGNTO_1 #:nodoc:
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# Round up a length to a multiple of NLMSG_ALIGNTO bytes
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def self.align(n)
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(n + NLMSG_ALIGNTO_1) & NLMSG_ALIGNTO_1_MASK
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end
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PADDING = ("\000" * NLMSG_ALIGNTO).freeze #:nodoc:
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# Pad a string up to a multiple of NLMSG_ALIGNTO bytes. Returns str.
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def self.pad(str)
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str << PADDING[0, align(str.bytesize) - str.bytesize]
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end
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end
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class Link < Message
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code RTM_NEWLINK, RTM_DELLINK, RTM_GETLINK
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uchar :family
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uchar :pad
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ushort :type
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int :index
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uint :flags
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uint :change
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end
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class Addr < Message
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code RTM_NEWADDR, RTM_DELADDR, RTM_GETADDR
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uchar :family
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uchar :prefixlen
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uchar :flags
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uchar :scope
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int :index
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end
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class Route < Message
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code RTM_NEWROUTE, RTM_DELROUTE, RTM_GETROUTE
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uchar :family
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uchar :dst_len
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uchar :src_len
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uchar :tos
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uchar :table
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uchar :protocol
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uchar :scope
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uchar :type
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uint :flags
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end
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end
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