Class: Codec::Tlv

Inherits:
Prefixedlength show all
Defined in:
lib/codec/tlv.rb

Instance Attribute Summary

Attributes inherited from Base

#id

Instance Method Summary collapse

Methods inherited from Prefixedlength

#build_field, #get_length

Methods inherited from Base

#add_sub_codec, #build_field, #encode_with_length, #eval_length, #get_length, #get_sub_codecs

Constructor Details

#initialize(id, length, header, content) ⇒ Tlv

Returns a new instance of Tlv.



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# File 'lib/codec/tlv.rb', line 3

def initialize(id,length,header,content)
  super(id,length,content)
  unless  header.kind_of?(Codec::Base)
    raise InitializeException," Invalid tag codec for Tlv class"
  end
  @tag_codec = header
  @subCodecs = {}
end

Instance Method Details

#decode(buffer) ⇒ Object 



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# File 'lib/codec/tlv.rb', line 35

def decode(buffer)
  msg = Field.new(@id)
  while(buffer.length > 0)
    begin
      tag,buffer = @tag_codec.decode(buffer)
    rescue => e
      val = Field.new("ERR")
      val.set_value("[#{buffer.unpack("H*").first}]")
      msg.add_sub_field(val)
      Logger.error("in #{@id} tlv codec: #{e.message}\n #{e.backtrace.join(10.chr)}")
      Logger.error("Decoding failed for #{id} : #{msg.to_yaml}")
      return msg,""
    end
    begin
      if @subCodecs[tag.get_value.to_s].nil?
        val,buffer = super(buffer)
      else
        l,buf = @length_codec.decode(buffer)
        val,buffer = @subCodecs[tag.get_value.to_s].decode_with_length(buf,l.get_value.to_i)
      end
    rescue BufferUnderflow => e
      val = Field.new
      val.set_value("Buffer underflow when parsing this tag : #{e.message} [#{buffer.unpack("H*").first}]")
      buffer = ""
    rescue 
      val = Field.new
      val.set_value("Parsing error [#{buffer.unpack("H*").first}]")
      buffer = ""
    end
    
    val.set_id(tag.get_value.to_s)
    msg.add_sub_field(val)
  end
  return msg,buffer
end

#decode_with_length(buf, length) ⇒ Object 



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# File 'lib/codec/tlv.rb', line 12

def decode_with_length(buf,length)
  l = eval_length(buf,length)
  f,r = decode(buf[0,l])
  Logger.warn("Remain data in a tlv buffer :[#{r.unpack("H*").first}]") if r.nil? || r.length > 0
  return f,buf[l,buf.length]
end

#encode(field) ⇒ Object 



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# File 'lib/codec/tlv.rb', line 19

def encode(field)
  out = ""
  fields = field.get_value
  fields.each do |sf|
    out += @tag_codec.encode(Field.new('*',sf.get_id))
    if @subCodecs[sf.get_id]
      content = @subCodecs[sf.get_id].encode(sf)
      length_buffer = @length_codec.encode(Field.new('*',content.length))
      out += length_buffer + content
    else
      out += super(sf)
    end
  end
  return out
end