Resolves ether_type incompatibility in packet.Frame

Frame:new() was populating the value as a 16-bit integer while
Frame:build_ether_frame() was expectng a two-byte string
Ethertype constants from various locations have been migrated to packet.lua

CHANGELOG

@@ -20,6 +20,9 @@ o [GH#2901, GH#2744, GH#2745] Arbitrary separator in stdnse.tohex() is now
   supported. Script smb-protocols now reports SMB dialects correctly.
   [nnposter]
 
+o [NSE] ether_type inconsistency in packet.Frame has been resolved. Bothi
+  Frame:new() and Frame:build_ether_frame() now use an integer. [nnposter]
+
 o [GH#2900, GH#2896, GH#2897] Nmap is now able to scan IP protocol 255.
   [nnposter]
 

nselib/eap.lua

@@ -41,8 +41,6 @@ _ENV = stdnse.module("eap", stdnse.seeall)
 -- Created 02/23/2012 - v0.1
 
 local ETHER_BROADCAST = "01:80:c2:00:00:03"
-local ETHER_TYPE_EAPOL_N = 0x888E
-local ETHER_TYPE_EAPOL = string.pack(">I2",ETHER_TYPE_EAPOL_N)
 local ETHER_HEADER_SIZE = 14
 local EAPOL_HEADER_SIZE = 4
 local EAP_HEADER_SIZE = 5
@@ -162,7 +160,7 @@ local make_eapol = function (arg)
   local p = packet.Frame:new()
   p.mac_src = arg.src
   p.mac_dst = packet.mactobin(ETHER_BROADCAST)
-  p.ether_type = ETHER_TYPE_EAPOL
+  p.ether_type = packet.ETHER_TYPE_EAPOL
 
   p.buf = string.pack(">BBs2", arg.version, arg.type, arg.payload)
   p:build_ether_frame()
@@ -202,7 +200,7 @@ parse = function (pkt)
   stdnse.debug1("mac_src: %s, mac_dest: %s, ether_type: 0x%X",
   tb.mac_src_str, tb.mac_dst_str, tb.ether_type)
 
-  if tb.ether_type ~= ETHER_TYPE_EAPOL_N then return nil, "not an eapol packet" end
+  if tb.ether_type ~= packet.ETHER_TYPE_EAPOL then return nil, "not an eapol packet" end
 
   stdnse.debug2("version: %X, type: %s, length: 0x%X",
   tb.version, eapol_str[tb.type] or "unknown",

nselib/packet.lua

@@ -135,8 +135,12 @@ ND_OPT_MTU = 5
 ND_OPT_RTR_ADV_INTERVAL = 7
 ND_OPT_HOME_AGENT_INFO = 8
 
-ETHER_TYPE_IPV4 = "\x08\x00"
+ETHER_TYPE_IPV4 = 0x0800
-ETHER_TYPE_IPV6 = "\x86\xdd"
+ETHER_TYPE_IPV6 = 0x86dd
+ETHER_TYPE_PPPOE_DISCOVERY = 0x8863
+ETHER_TYPE_PPPOE_SESSION = 0x8864
+ETHER_TYPE_EAPOL = 0x888e
+ETHER_TYPE_ATAOE = 0x88a2
 
 ----------------------------------------------------------------------------------------------------------------
 -- Frame is a class
@@ -160,7 +164,7 @@ end
 --- Build an Ethernet frame.
 -- @param mac_dst six-byte string of the destination MAC address.
 -- @param mac_src six-byte string of the source MAC address.
--- @param ether_type two-byte string of the type.
+-- @param ether_type IEEE 802 ethertype as a 16-bit integer (0x0800 for IPv4)
 -- @param packet string of the payload.
 -- @return frame string of the Ether frame.
 function Frame:build_ether_frame(mac_dst, mac_src, ether_type, packet)
@@ -171,7 +175,7 @@ function Frame:build_ether_frame(mac_dst, mac_src, ether_type, packet)
   if not self.ether_type then
     return nil, "Unknown packet type."
   end
-  self.frame_buf = self.mac_dst..self.mac_src..self.ether_type..self.buf
+  self.frame_buf = self.mac_dst..self.mac_src..(">I2"):pack(self.ether_type)..self.buf
 end
 --- Parse an Ethernet frame.
 -- @param frame string of the Ether frame.

nselib/pppoe.lua

@@ -30,11 +30,6 @@ local table = require "table"
 _ENV = stdnse.module("pppoe", stdnse.seeall)
 
 
-EtherType = {
-  PPPOE_DISCOVERY = 0x8863,
-  PPPOE_SESSION = 0x8864,
-}
-
 -- A Class to handle the Link Control Protocol LCP
 LCP = {
 
@@ -709,7 +704,7 @@ Comm = {
     local p = packet.Frame:new(l2..l3)
 
     -- there's probably a more elegant way of doing this
-    if ( EtherType.PPPOE_DISCOVERY == p.ether_type ) then
+    if ( packet.ETHER_TYPE_PPPOE_DISCOVERY == p.ether_type ) then
       if ( header.code == PPPoE.Code.PADO ) then
         local pado = PPPoE.PADO.parse(l3)
         pado.mac_srv = p.mac_src
@@ -721,7 +716,7 @@ Comm = {
         local pads = PPPoE.PADT.parse(l3)
         return true, pads
       end
-    elseif ( EtherType.PPPOE_SESSION == p.ether_type ) then
+    elseif ( packet.ETHER_TYPE_PPPOE_SESSION == p.ether_type ) then
       return true, PPPoE.SessionData.parse(l3)
     end
     return false, ("Received unsupported response, can't decode code (%d)"):format(header.code)

scripts/broadcast-ataoe-discover.nse

@@ -105,14 +105,14 @@ ATAoE = {
 -- Send a Config Info Request to the ethernet broadcast address
 -- @param iface table as returned by nmap.get_interface_info()
 local function sendConfigInfoRequest(iface)
-  local ETHER_BROADCAST, P_ATAOE = "ff:ff:ff:ff:ff:ff", 0x88a2
+  local ETHER_BROADCAST = "ff:ff:ff:ff:ff:ff"
   local req = ATAoE.ConfigInfoRequest:new()
   local tag = req.tag
 
   local p = packet.Frame:new()
   p.mac_src = iface.mac
   p.mac_dst = packet.mactobin(ETHER_BROADCAST)
-  p.ether_type = string.pack(">I2", P_ATAOE)
+  p.ether_type = packet.ETHER_TYPE_ATAOE
   p.buf = tostring(req)
   p:build_ether_frame()
 

scripts/broadcast-dhcp-discover.nse

@@ -147,8 +147,7 @@ local function dhcp_listener(sock, iface, macaddr, options, timeout, xid, result
   -- Add the Ethernet header
   frame:build_ether_frame(
     "\xff\xff\xff\xff\xff\xff",
-    iface.mac, -- can't use macaddr or we won't see response
+    iface.mac) -- can't use macaddr or we won't see response
-    packet.ETHER_TYPE_IPV4)
 
   local dnet = nmap.new_dnet()
   dnet:ethernet_open(iface.device)