Gather available offloading modes

Gather available offloading modes for physical interfaces
during the bootstrap stage. In this commit 'ethtool' util
output parsing approach has been used. Nailgun agent
collects modes and sent it to the nailgun API. These modes
will be parsed via nailgun and will be put into
offloading_modes JSON field of the interface db model.

Change-Id: I172b61d3fccc00e5951616646fa82e33b8322997
Implements: blueprint selectable-offloading-type

bin/agent

@@ -114,6 +114,15 @@ class McollectiveConfig
   end
 end
 
+class Offloading
+  def initialize(name, sub)
+    @name, @sub = name, sub
+  end
+
+  def to_json(options = {})
+    {'name' => @name, 'state' => nil, 'sub' => @sub}.to_json()
+  end
+end
 
 class NodeAgent
   def initialize(logger, url=nil)
@@ -193,6 +202,38 @@ class NodeAgent
     interfaces
   end
 
+  # transform input array into array of the objects
+  # Example:
+  # [{
+  #     "state":null,
+  #     "sub":[
+  #         {
+  #             "state":null,
+  #             "sub":[],
+  #             "name":"tx-checksum-ipv6"
+  #         },
+  #         ...........
+  #     ],
+  #     "name":"tx-checksumming"
+  # },
+  # {
+  #     "state":null,
+  #     "sub":[],
+  #     "name":"generic-segmentation-offload"
+  # },
+  # .............
+  # ]
+  def _parse_offloading(offloading_arr)
+    return [] if offloading_arr.empty?
+    inner = []
+    current = offloading_arr.shift()
+    while offloading_arr.any? && offloading_arr.first().start_with?("\t") do
+      inner << offloading_arr.shift()[1..-1]
+    end
+    res = _parse_offloading(offloading_arr)
+    res << Offloading.new(current, _parse_offloading(inner))
+  end
+
   def _detailed
     detailed_meta = {
       :system => _system_info,
@@ -238,6 +279,33 @@ class NodeAgent
             int_meta[:netmask] = addrinfo[:netmask] if addrinfo[:netmask]
           end
         end
+        begin
+          # this stuff will put all non-fixed offloading mode into array
+          # collect names of non-fixed offloading modes
+          # Example of ethtool -k ethX output:
+          # tx-checksumming: on
+          # 	tx-checksum-ipv4: on
+          # 	tx-checksum-ip-generic: off [fixed]
+          # 	tx-checksum-ipv6: on
+          # 	tx-checksum-fcoe-crc: off [fixed]
+          # 	tx-checksum-sctp: on
+          # scatter-gather: on
+          # 	tx-scatter-gather: on
+          # 	tx-scatter-gather-fraglist: off [fixed]
+          # generic-segmentation-offload: on
+          offloading_data = `ethtool -k #{int}`.split("\n").reject { |offloading|
+                                 offloading.include?("Features for") ||
+                                 offloading.include?("fixed")
+                            }.map { |offloading|
+                                 offloading.split(':')[0]
+                            }
+          # transform raw data into array of objects
+          int_meta[:offloading_modes] = _parse_offloading(offloading_data)
+        rescue
+          # in case if we have no `ethtool` package installed we should
+          # return empty array to support nailgun's rest api call
+          int_meta[:offloading_modes] = []
+        end
         detailed_meta[:interfaces] << int_meta
       end
     rescue Exception => e