Class: ScanBeacon::BeaconParser

Inherits:
Object
  • Object
show all
Defined in:
lib/scan_beacon/beacon_parser.rb

Constant Summary collapse

DEFAULT_LAYOUTS = 
{
  altbeacon: "m:2-3=beac,i:4-19,i:20-21,i:22-23,p:24-24,d:25-25",
  eddystone_uid: "s:0-1=feaa,m:2-2=00,p:3-3:-41,i:4-13,i:14-19;d:20-21",
  eddystone_url: "s:0-1=feaa,m:2-2=10,p:3-3:-41,i:4-21v",
  eddystone_tlm: "s:0-1=feaa,m:2-2=20,d:3-3,d:4-5,d:6-7,d:8-11,d:12-15",
  eddystone_eid: "s:0-1=feaa,m:2-2=30,p:3-3:-41,i:4-11",
}
AD_TYPE_MFG = 
0xff
AD_TYPE_SERVICE = 
0x03
BT_EIR_SERVICE_DATA = 
"\x16".force_encoding("ASCII-8BIT")

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(beacon_type, layout) ⇒ BeaconParser

Returns a new instance of BeaconParser.



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# File 'lib/scan_beacon/beacon_parser.rb', line 19

def initialize(beacon_type, layout)
  @beacon_type = beacon_type
  if layout.include?("s")
    @ad_type = AD_TYPE_SERVICE
  else
    @ad_type = AD_TYPE_MFG
  end
  @layout = layout
  parse_layout
end

Instance Attribute Details

#beacon_type ⇒ Object

Returns the value of attribute beacon_type.



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# File 'lib/scan_beacon/beacon_parser.rb', line 13

def beacon_type
  @beacon_type
end

Class Method Details

.default_parsers ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 15

def self.default_parsers
  DEFAULT_LAYOUTS.map {|name, layout| BeaconParser.new name, layout }
end

Instance Method Details

#generate_ad(beacon) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 108

def generate_ad(beacon)
  length = [@matchers, @ids, @power, @data_fields].flatten.map {|elem| elem[:start] }.max + 1
  ad = ("\x00" * length).force_encoding("ASCII-8BIT")
  @matchers.each do |matcher|
    ad[matcher[:start]..matcher[:end]] = matcher[:expected]
  end
  @ids.each_with_index do |id, index|
    if id[:var_length]
      id_bytes = Beacon::Field.new(hex: beacon.ids[index]).bytes
      ad[id[:start]..id[:start]+id_bytes.size] = id_bytes
    else
      id_bytes = Beacon::Field.field_with_length(beacon.ids[index], id[:length]).bytes
      ad[id[:start]..id[:end]] = id_bytes
    end
  end
  @data_fields.each_with_index do |field, index|
    unless beacon.data[index].nil?
      field_bytes = Beacon::Field.field_with_length(beacon.data[index], field[:length]).bytes
      ad[field[:start]..field[:end]] = field_bytes
    end
  end
  ad[@power[:start]..@power[:end]] = [beacon.power].pack('c')
  length = ad.size
  if @ad_type == AD_TYPE_SERVICE
    "\x03\x03".force_encoding("ASCII-8BIT") + [beacon.service_uuid].pack("S<") + [length+1].pack('C') + BT_EIR_SERVICE_DATA + ad
  elsif @ad_type == AD_TYPE_MFG
    ad[0..1] = [beacon.mfg_id].pack("S<")
    [length+1].pack('C') + [AD_TYPE_MFG].pack('C') +  ad
  end
end

#inspect ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 139

def inspect
  "<BeaconParser type=\"#{@beacon_type}\", layout=\"#{@layout}\">"
end

#matches?(data) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/scan_beacon/beacon_parser.rb', line 64

def matches?(data)
  @matchers.each do |matcher|
    return false unless data[matcher[:start]..matcher[:end]] == matcher[:expected]
  end
  return true
end

#parse(data, ad_type = AD_TYPE_MFG) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 71

def parse(data, ad_type = AD_TYPE_MFG)
  return nil if ad_type != @ad_type || !matches?(data)
  if @ad_type == AD_TYPE_MFG
    Beacon.new(ids: parse_ids(data), power: parse_power(data), beacon_type: @beacon_type,
      data: parse_data_fields(data), mfg_id: parse_mfg_or_service_id(data))
  else
    Beacon.new(ids: parse_ids(data), power: parse_power(data), beacon_type: @beacon_type,
      data: parse_data_fields(data), service_uuid: parse_mfg_or_service_id(data))
  end
end

#parse_data_fields(data) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 86

def parse_data_fields(data)
  parse_elems(@data_fields, data)
end

#parse_elems(elems, data) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 90

def parse_elems(elems, data)
  elems.map {|elem|
    elem_str = data[elem[:start]..elem[:end]]
    Beacon::Field.new(bytes: elem_str)
  }
end

#parse_ids(data) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 82

def parse_ids(data)
  parse_elems(@ids, data)
end

#parse_layout ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 30

def parse_layout
  @matchers = []
  @ids = []
  @data_fields = []
  @power = nil
  @layout.split(",").each do |field|
    field_type, range_start, range_end, expected = field.split(/:|=|-/)
    field_params = {
      start: range_start.to_i,
      end: range_end.to_i,
      length: range_end.to_i - range_start.to_i + 1,
    }
    if range_end.end_with? 'v'
      field_params[:var_length] = true
    end
    field_params[:expected] = [expected].pack("H*") unless expected.nil?
    case field_type
    when 'm'
      @matchers << field_params
    when 's'
      # swap byte order of service uuid
      expected = field_params[:expected]
      field_params[:expected] = expected[1] + expected[0]
      @matchers << field_params
    when 'i'
      @ids << field_params
    when 'd'
      @data_fields << field_params
    when 'p'
      @power = field_params
    end
  end
end

#parse_mfg_or_service_id(data) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 97

def parse_mfg_or_service_id(data)
  data[0..1].unpack('S<')[0]
end

#parse_power(data) ⇒ Object 



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# File 'lib/scan_beacon/beacon_parser.rb', line 101

def parse_power(data)
  return nil if @power.nil?
  power_data = data[@power[:start]..@power[:end]]
  return nil if power_data.nil?
  power_data.unpack('c')[0]
end