Method: LogStash::Codecs::Netflow#decode

Defined in:
lib/logstash/codecs/netflow.rb

#decode(payload, &block) ⇒ Object 



32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
 
# File 'lib/logstash/codecs/netflow.rb', line 32

def decode(payload, &block)
  header = Header.read(payload)

  unless @versions.include?(header.version)
    @logger.warn("Ignoring Netflow version v#{header.version}")
    return
  end

  if header.version == 5
    flowset = Netflow5PDU.read(payload)
  elsif header.version == 9
    flowset = Netflow9PDU.read(payload)
  else
    @logger.warn("Unsupported Netflow version v#{header.version}")
    return
  end

  flowset.records.each do |record|
    if flowset.version == 5
      event = LogStash::Event.new

      # FIXME Probably not doing this right WRT JRuby?
      #
      # The flowset header gives us the UTC epoch seconds along with
      # residual nanoseconds so we can set @timestamp to that easily
      event["@timestamp"] = Time.at(flowset.unix_sec, flowset.unix_nsec / 1000).utc
      event[@target] = {}

      # Copy some of the pertinent fields in the header to the event
      ['version', 'flow_seq_num', 'engine_type', 'engine_id', 'sampling_algorithm', 'sampling_interval', 'flow_records'].each do |f|
        event[@target][f] = flowset[f]
      end

      # Create fields in the event from each field in the flow record
      record.each_pair do |k,v|
        case k.to_s
        when /_switched$/
          # The flow record sets the first and last times to the device
          # uptime in milliseconds. Given the actual uptime is provided
          # in the flowset header along with the epoch seconds we can
          # convert these into absolute times
          millis = flowset.uptime - v
          seconds = flowset.unix_sec - (millis / 1000)
          micros = (flowset.unix_nsec / 1000) - (millis % 1000)
          if micros < 0
            seconds--
            micros += 1000000
          end
          # FIXME Again, probably doing this wrong WRT JRuby?
          event[@target][k.to_s] = Time.at(seconds, micros).utc.strftime("%Y-%m-%dT%H:%M:%S.%3NZ")
        else
          event[@target][k.to_s] = v
        end
      end

      yield event
    elsif flowset.version == 9
      case record.flowset_id
      when 0
        # Template flowset
        record.flowset_data.templates.each do |template|
          catch (:field) do
            fields = []
            template.fields.each do |field|
              entry = netflow_field_for(field.field_type, field.field_length)
              if ! entry
                throw :field
              end
              fields += entry
            end
            # We get this far, we have a list of fields
            #key = "#{flowset.source_id}|#{event["source"]}|#{template.template_id}"
            key = "#{flowset.source_id}|#{template.template_id}"
            @templates[key, @cache_ttl] = BinData::Struct.new(:endian => :big, :fields => fields)
            # Purge any expired templates
            @templates.cleanup!
          end
        end
      when 1
        # Options template flowset
        record.flowset_data.templates.each do |template|
          catch (:field) do
            fields = []
            template.option_fields.each do |field|
              entry = netflow_field_for(field.field_type, field.field_length)
              if ! entry
                throw :field
              end
              fields += entry
            end
            # We get this far, we have a list of fields
            #key = "#{flowset.source_id}|#{event["source"]}|#{template.template_id}"
            key = "#{flowset.source_id}|#{template.template_id}"
            @templates[key, @cache_ttl] = BinData::Struct.new(:endian => :big, :fields => fields)
            # Purge any expired templates
            @templates.cleanup!
          end
        end 
      when 256..65535
        # Data flowset
        #key = "#{flowset.source_id}|#{event["source"]}|#{record.flowset_id}"
        key = "#{flowset.source_id}|#{record.flowset_id}"
        template = @templates[key]

        if ! template
          #@logger.warn("No matching template for flow id #{record.flowset_id} from #{event["source"]}")
          @logger.warn("No matching template for flow id #{record.flowset_id}")
          next
        end

        length = record.flowset_length - 4

        # Template shouldn't be longer than the record and there should
        # be at most 3 padding bytes
        if template.num_bytes > length or ! (length % template.num_bytes).between?(0, 3)
          @logger.warn("Template length doesn't fit cleanly into flowset", :template_id => record.flowset_id, :template_length => template.num_bytes, :record_length => length) 
          next
        end

        array = BinData::Array.new(:type => template, :initial_length => length / template.num_bytes)

        records = array.read(record.flowset_data)

        records.each do |r|
          event = LogStash::Event.new(
            "@timestamp" => Time.at(flowset.unix_sec).utc,
            @target => {}
          )

          # Fewer fields in the v9 header
          ['version', 'flow_seq_num'].each do |f|
            event[@target][f] = flowset[f]
          end

          event[@target]['flowset_id'] = record.flowset_id

          r.each_pair do |k,v|
            case k.to_s
            when /_switched$/
              millis = flowset.uptime - v
              seconds = flowset.unix_sec - (millis / 1000)
              # v9 did away with the nanosecs field
              micros = 1000000 - (millis % 1000)
              event[@target][k.to_s] = Time.at(seconds, micros).utc.strftime("%Y-%m-%dT%H:%M:%S.%3NZ")
            else
              event[@target][k.to_s] = v
            end
          end

          yield event
        end
      else
        @logger.warn("Unsupported flowset id #{record.flowset_id}")
      end
    end
  end
end