Add some special use IPv4 addresses to isPrivate which are described in RFC 5736

and RFC 5737, published in Jan 2010. Improve performance of isPrivate for IPv4
addresses by using ip_in_range less frequently. Add an extra return value to
isPrivate - when the first return value is true, the second return value will
now be a string representing the special use assignment in which the supplied
address is located.

CHANGELOG

@@ -1,5 +1,12 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE] Add some special use IPv4 addresses to isPrivate which are described in
+  RFC 5736 and RFC 5737, published in Jan 2010. Improve performance of isPrivate
+  for IPv4 addresses by using ip_in_range less frequently. Add an extra return
+  value to isPrivate - when the first return value is true, the second return
+  value will now be a string representing the special use assignment in which
+  the supplied address is located. [jah]
+
 o [Nmap, Ncat, Nping] The default unit for time specifications is now
   seconds, not milliseconds, and times may have a decimal point. 1000
   now means 1000 seconds, or about 17 minutes, not 1000 milliseconds.

nselib/ipOps.lua

@@ -22,6 +22,11 @@ module ( "ipOps" )
 -- * IPv4 Loopback (RFC3330)
 -- * IPv4 Private Use (RFC1918)
 -- * IPv4 Link Local (RFC3330)
+-- * IPv4 IETF Protocol Assignments (RFC 5736)
+-- * IPv4 TEST-NET-1, TEST-NET-2, TEST-NET-3 (RFC 5737)
+-- * IPv4 Network Interconnect Device Benchmark Testing (RFC 2544)
+-- * IPv4 Reserved for Future Use (RFC 1112, Section 4)
+-- * IPv4 Multicast Local Network Control Block (RFC 3171, Section 3)
 -- * IPv6 Unspecified and Loopback (RFC3513)
 -- * IPv6 Unique Local Unicast (RFC4193)
 -- * IPv6 Link Local Unicast (RFC4291)
@@ -30,29 +35,83 @@ module ( "ipOps" )
 -- @usage
 -- local is_private = ipOps.isPrivate( "192.168.1.1" )
 -- @return True or false (or <code>nil</code> in case of an error).
--- @return String error message in case of an error.
+-- @return String error message in case of an error or
+--         String non-routable address containing the supplied IP address.
 isPrivate = function( ip )
   local err
 
   ip, err = expand_ip( ip )
   if err then return nil, err end
 
-  local ipv4_private = { "10/8", "127/8", "169.254/16", "172.16/12", "192.168/16" }
-  local ipv6_private = { "::/127", "FC00::/7", "FE80::/10" }
-  local t, is_private = {}
   if ip:match( ":" ) then
-    t = ipv6_private
-  else
-    t = ipv4_private
+
+    local is_private
+    local ipv6_private = { "::/127", "FC00::/7", "FE80::/10" }
+
+    for _, range in ipairs( ipv6_private ) do
+      is_private, err = ip_in_range( ip, range )
+      if is_private == true then
+        return true, range
+      end
+      if err then
+        return nil, err
+      end
+    end
+
+  elseif ip:sub(1,3) == '10.' then
+
+    return true, '10/8'
+
+  elseif ip:sub(1,4) == '127.' then
+
+    return true, '127/8'
+
+  elseif ip:sub(1,8) == '169.254.' then
+
+    return true, '169.254/16'
+
+  elseif ip:sub(1,4) == '172.' then
+
+    local p, e = ip_in_range(ip, '172.16/12')
+    if p == true then
+      return true, '172.16/12'
+    else
+      return p, e
+    end
+
+  elseif ip:sub(1,4) == '192.' then
+
+    if ip:sub(5,8) == '168.' then
+      return true, '192.168/16'
+    elseif ip:match('^192%.[0][0]?[0]?%.[0][0]?[0]?%.') then
+      return true, '192.0.0/24'
+    elseif ip:match('^192%.[0][0]?[0]?%.[0]?[0]?2') then
+      return true, '192.0.2/24'
+    end
+
+  elseif ip:sub(1,4) == '198.' then
+
+    if ip:match('^198%.[0]?18%.') or ip:match('^198%.[0]?19%.') then
+      return true, '198.18/15'
+    elseif ip:match('^198%.[0]?51%.100%.') then
+      return true, '198.51.100/24'
+    end
+
+  elseif ip:match('^203%.[0][0]?[0]?%.113%.') then
+
+    return true, '203.0.113/24'
+
+  elseif ip:match('^224%.[0][0]?[0]?%.[0][0]?[0]?%.') then
+
+    return true, '224.0.0/24'
+
+  elseif ip:match('^24[0-9]%.') or ip:match('^25[0-5]%.') then
+
+    return true, '240.0.0/4'
+
   end
 
-  for _, range in ipairs( t ) do
-    is_private, err = ip_in_range( ip, range )
-    -- return as soon as is_private is true or err
-    if is_private then return true end
-    if err then return nil, err end
-  end
-  return false
+  return false, nil
 
 end