Add PDU mode support and GSM 7Bit encoding / decoding

lib/biju.rb

@@ -1,5 +1,6 @@
 require 'biju/version'
 require 'biju/modem'
+require 'biju/pdu'
 require 'biju/to_hayes'
 require 'biju/hayes'
 require 'biju/sms'

lib/biju/pdu.rb

@@ -0,0 +1,63 @@
+require 'biju/pdu/gsm7bit'
+
+module Biju
+  module PDU
+    ENCODING = {
+      gsm7bit: GSM7Bit,
+    }
+
+    def self.encode(hash)
+    end
+
+    def self.encode_user_data(message, encoding = :gsm7bit)
+      raise ArgumentError, "Unknown encoding" unless ENCODING.has_key?(encoding)
+      ENCODING[encoding].encode(message)
+    end
+
+    def self.decode(string)
+      res = {
+        smsc_length: string[0..1],
+        smsc_type: string[2..3],
+        smsc_number: string[4..15],
+
+        address_length: string[18..19].to_i(16),
+        address_type: string[20..21],
+
+        protocol_identifier: string[34..35],
+        data_coding_scheme: string[36..37],
+        timestamp: DateTime.strptime(
+          "#{string[38..49].reverse}+#{string[50..51].reverse}",
+          '%S%M%H%d%m%y%Z'),
+        user_data_length: string[52..53],
+      }
+      res[:sender_number] = string[22..(22 + res[:address_length])]
+      res[:user_data] = PDU.decode_user_data(
+        string[54..-1], res[:data_coding_scheme])
+
+      res
+    end
+
+    def self.decode_user_data(message, encoding = '00')
+      encoding = data_coding_scheme(encoding) unless encoding.is_a?(Symbol)
+
+      raise ArgumentError, "Unknown encoding" unless ENCODING.has_key?(:gsm7bit)
+      ENCODING[:gsm7bit].decode(message)
+    end
+
+    def self.data_coding_scheme(dcs)
+      dcs = dcs.hex if dcs.is_a?(String)
+      if dcs & 0b11000000 == 0
+        case dcs & 0b00001100
+        when 0
+          :gsm7bit
+        when 4
+          :gsm8bit
+        when 8
+          :ucs2
+        when 12
+          :reserved
+        end
+      end
+    end
+  end
+end

lib/biju/pdu/gsm7bit.rb

@@ -0,0 +1,81 @@
+module Biju::PDU
+  class GSM7Bit
+    BASIC_7BIT_CHARACTER_SET = [
+      '@', '£', '$', '¥', 'è', 'é', 'ù', 'ì', 'ò', 'Ç', "\n", 'Ø', 'ø', "\r", 'Å', 'å',
+      "\u0394", '_', "\u03a6", "\u0393", "\u039b", "\u03a9", "\u03a0","\u03a8", "\u03a3", "\u0398", "\u039e", "\e", 'Æ', 'æ', 'ß', 'É',
+      ' ', '!', '"', '#', '¤', '%', '&', '\'', '(', ')','*', '+', ',', '-', '.', '/',
+      '0', '1', '2', '3', '4', '5', '6', '7','8', '9', ':', ';', '<', '=', '>', '?',
+      '¡', 'A', 'B', 'C', 'D', 'E','F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
+      'P', 'Q', 'R', 'S','T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'Ä', 'Ö', 'Ñ', 'Ü', '§',
+      '¿', 'a','b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
+      'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'ä', 'ö', 'ñ','ü', 'à'
+    ]
+
+    BASIC_7BIT_CHARACTER_SET_EXTENSION = {
+      0x0A => "\n",
+      0x0D => '',
+      0x14 => '^',
+      0x1B => '',
+      0x28 => '{',
+      0x29 => '}',
+      0x2F => '\\',
+      0x3C => '[',
+      0x3D => '~',
+      0x3E => ']',
+      0x40 => '|',
+      0x65 => '€',
+    }
+
+    def self.decode(string)
+      res = ''
+      next_char = 0
+
+      string.scan(/../).map(&:hex).each_with_index do |octet, i|
+        index = i % 7
+        current = ((octet & (2 ** (7 - index) - 1)) << index) | next_char
+
+        res = add_char(res, current)
+
+        next_char = octet >> (7 - index)
+        if index == 6
+          res = add_char(res, next_char)
+          next_char = 0
+        end
+      end
+
+      res
+    end
+
+    def self.encode(string)
+      res = ''
+      string.chars.each do |char|
+        if get_septet(char)
+          res << get_septet(char).reverse
+        elsif get_septet(char, escape: true)
+          res << get_septet("\e").reverse
+          res << get_septet(char, escape: true).reverse
+        end
+      end
+      res << ("0" * (8 - (res.length % 8))) unless res.length % 8 == 0
+
+      res.scan(/.{8}/).map { |octet| "%02x" % octet.reverse.to_i(2) }.join
+    end
+
+    private
+
+    def self.add_char(string, char)
+      if string[-1] == "\e"
+        string.chop << BASIC_7BIT_CHARACTER_SET_EXTENSION[char]
+      else
+        string << BASIC_7BIT_CHARACTER_SET[char]
+      end
+    end
+
+    def self.get_septet(char, escape: false)
+      char = (!escape ? BASIC_7BIT_CHARACTER_SET.index(char) : BASIC_7BIT_CHARACTER_SET_EXTENSION.key(char))
+
+      return nil unless char
+      "%07b" % char
+    end
+  end
+end

lib/biju/sms.rb

@@ -5,6 +5,13 @@ module Biju
     attr_accessor :id, :phone_number, :message
     attr_reader :datetime
 
+    def self.from_pdu(string)
+      sms_infos = PDU.decode(string)
+      new(phone_number: sms_infos[:sender_number],
+          datetime: sms_infos[:timestamp],
+          message: sms_infos[:user_data])
+    end
+
     def initialize(params={})
       params.each do |attr, value|
         self.public_send("#{attr}=", value)
@@ -23,7 +30,10 @@ module Biju
     end
 
     def to_s
-      "#{id} - #{phone_number} - #{datetime} - #{message}"
+      "[#{id}] (#{phone_number}) #{datetime} '#{message}'"
+    end
+
+    def to_pdu
     end
   end
 end