New C backend for datafiles.lua; avoid copies of large data sets

nselib/datafiles.lua

@@ -15,6 +15,8 @@ local nmap = require "nmap"
 local stdnse = require "stdnse"
 local string = require "string"
 local table = require "table"
+-- mostly undocumented library for direct lookups in Nmap datafiles:
+local nmapdb = require "nmapdb"
 _ENV = stdnse.module("datafiles", stdnse.seeall)
 
 
@@ -72,59 +74,71 @@ parse_rpc = function()
   return parse_and_cache("nmap-rpc")
 end
 
+local prohibited = function()
+  error("Invalid function")
+end
+local services_table = {}
+local portlookup_mt = {
+  __index = function(t, port)
+    return nmapdb.getservbyport(port, rawget(t, "proto"))
+  end,
+  __newindex = prohibited,
+}
+for _, proto in ipairs({"tcp", "udp", "sctp"}) do
+  services_table[proto] = setmetatable({proto=proto}, portlookup_mt)
+end
 
 ---
 -- Read and parse <code>nmap-services</code>.
 --
--- On success, return true and a table containing two subtables, indexed by the
--- keys "tcp" and "udp". The <code>tcp</code> subtable maps TCP port numbers to
--- service names, and the <code>udp</code> subtable is the same for UDP. You can
--- pass "tcp" or "udp" as an argument to <code>parse_services</code> to get
+-- On success, return true and a table containing subtables indexed by the
+-- keys "tcp", "udp", and "sctp". You can
+-- pass a protocol name as an argument to <code>parse_services</code> to get
 -- only one of the results tables.
--- @param protocol The protocol table to return (<code>"tcp"</code> or
+-- @param protocol Optional: The protocol table to return (e.g. <code>"tcp"</code> or
 -- <code>"udp"</code>).
 -- @return Status (true or false).
 -- @return Table (if status is true) or error string (if status is false).
 -- @see parse_file
 parse_services = function(protocol)
-  if protocol and protocol ~= "tcp" and protocol ~= "udp" then
-    return false, "Bad protocol for nmap-services: use tcp or udp"
-  end
-
-  local services_table
-  nmap.registry.datafiles = nmap.registry.datafiles or {}
-  nmap.registry.datafiles.services = nmap.registry.datafiles.services or {}
+  local t
   if protocol then
-    if not nmap.registry.datafiles.services[protocol] then
-      local status
-      status, nmap.registry.datafiles.services[protocol] = parse_file("nmap-services", protocol)
-      if not status then
-        return false, "Error parsing nmap-services"
-      end
+    t = services_table[protocol]
+    if not t then
+      return false, "Bad protocol for nmap-services"
     end
-    services_table = nmap.registry.datafiles.services[protocol]
   else
-    local status
-    status, nmap.registry.datafiles.services = parse_file("nmap-services")
-    if not status then
-      return false, "Error parsing nmap-services"
-    end
-    services_table = nmap.registry.datafiles.services
+    t = services_table
   end
 
-  return true, services_table
+  return true, t
 end
 
 
+local mac_table = setmetatable({}, {
+  __index = function(t, mac)
+    if #mac < 6 then
+      -- probably binary
+      mac = mac .. ("\0"):rep(6 - #mac)
+    elseif #mac < 12 then
+      -- probably hex
+      mac = mac .. ("0"):rep(12 - #mac)
+    end
+    return nmapdb.mac2corp(mac)
+  end,
+  __newindex = prohibited,
+})
 ---
 -- Read and parse <code>nmap-mac-prefixes</code>.
 --
--- On success, return true and a table mapping 3 byte MAC prefixes to manufacturer names.
+-- On success, return true and a table mapping MAC prefixes to manufacturer
+-- names. The whole MAC can also be used as a key, since the table calls an
+-- internal Nmap function to do the lookup.
 -- @return Status (true or false).
 -- @return Table (if status is true) or error string (if status is false).
 -- @see parse_file
 parse_mac_prefixes = function()
-  return parse_and_cache("nmap-mac-prefixes")
+  return true, mac_table
 end