Allow multiple files as input for make_ipfix_element_map()

The main purpose of this is to be able to store non-standard element
definitions in a separate file, like that for the reduced-size
encoding of tcpControlBits, which is also part of this commit. The v4
and v6 templates now use this instead of tcpControlBits to be
compatible with current versions of the nfdump suite.

src/apps/ipfix/ipfix-information-elements-local.inc

@@ -0,0 +1 @@
+6,tcpControlBitsReduced,unsigned8,,,,,,,,[RFC5102],,2013-02-18

src/apps/ipfix/template.lua

@@ -70,22 +70,26 @@ local function string_parser(str)
 end
 
 -- Parse out available IPFIX fields.
-local function make_ipfix_element_map()
-   local elems = require("apps.ipfix.ipfix_information_elements_inc")
-   local parser = string_parser(elems)
+local function make_ipfix_element_map(names)
    local map = {}
-   while not parser.is_done() do
-      local id = parser.consume_upto(",")
-      local name = parser.consume_upto(",")
-      local data_type = parser.consume_upto(",")
-      for i=1,8 do parser.consume_upto(",") end
-      parser.consume_upto("\n")
-      map[name] = { id = id, data_type = data_type }
+   for _, name in ipairs(names) do
+      local elems = require("apps.ipfix."..name.."_inc")
+      local parser = string_parser(elems)
+      while not parser.is_done() do
+         local id = parser.consume_upto(",")
+         local name = parser.consume_upto(",")
+         local data_type = parser.consume_upto(",")
+         for i=1,8 do parser.consume_upto(",") end
+         parser.consume_upto("\n")
+         map[name] = { id = id, data_type = data_type }
+      end
    end
    return map
 end
 
-local ipfix_elements = make_ipfix_element_map()
+local ipfix_elements =
+   make_ipfix_element_map({ 'ipfix_information_elements',
+                            'ipfix_information_elements_local' })
 
 local swap_fn_env = { htons = htons, htonl = htonl, htonq = htonq }
 
@@ -220,7 +224,7 @@ v4 = make_template_info {
               "flowEndMilliseconds",
               "packetDeltaCount",
               "octetDeltaCount",
-              "tcpControlBits" }
+              "tcpControlBitsReduced" }
 }
 
 local function extract_transport_key(entry, l4)
@@ -238,6 +242,16 @@ local function accumulate_tcp_flags(dst, new)
                                       new.value.tcpControlBits)
 end
 
+local function extract_tcp_flags_reduced(l4, entry)
+   entry.value.tcpControlBitsReduced = bit.band(0xFF, get_tcp_flags(l4))
+end
+
+local function accumulate_tcp_flags_reduced(dst, new)
+   dst.value.tcpControlBitsReduced =
+      bit.bor(dst.value.tcpControlBitsReduced,
+              new.value.tcpControlBitsReduced)
+end
+
 function v4.extract(pkt, timestamp, entry)
    local l2 = pkt.data
    local l3 = l2 + ethernet_header_size
@@ -262,7 +276,7 @@ function v4.extract(pkt, timestamp, entry)
    entry.value.packetDeltaCount = 1
    entry.value.octetDeltaCount = get_ipv4_total_length(l3)
    if proto == IP_PROTO_TCP then
-      extract_tcp_flags(entry, l4)
+      extract_tcp_flags_reduced(entry, l4)
    end
 end
 
@@ -272,7 +286,7 @@ function v4.accumulate(dst, new)
    dst.value.octetDeltaCount =
       dst.value.octetDeltaCount + new.value.octetDeltaCount
    if dst.key.protocolIdentifier == IP_PROTO_TCP then
-      accumulate_tcp_flags(dst, new)
+      accumulate_tcp_flags_reduced(dst, new)
    end
 end
 
@@ -300,7 +314,7 @@ v6 = make_template_info {
               "flowEndMilliseconds",
               "packetDeltaCount",
               "octetDeltaCount",
-              "tcpControlBits" }
+              "tcpControlBitsReduced" }
 }
 
 function v6.extract(pkt, timestamp, entry)
@@ -328,7 +342,7 @@ function v6.extract(pkt, timestamp, entry)
    entry.value.octetDeltaCount = get_ipv6_payload_length(l3)
       + ipv6_fixed_header_size
    if proto == IP_PROTO_TCP then
-      extract_tcp_flags(entry, l4)
+      extract_tcp_flags_reduced(entry, l4)
    end
 end
 
@@ -338,7 +352,7 @@ function v6.accumulate(dst, new)
    dst.value.octetDeltaCount =
       dst.value.octetDeltaCount + new.value.octetDeltaCount
    if dst.key.protocolIdentifier == IP_PROTO_TCP then
-      accumulate_tcp_flags(dst, new)
+      accumulate_tcp_flags_reduced(dst, new)
    end
 end