Index: nselib/smb.lua
===================================================================
--- nselib/smb.lua	(revision 36802)
+++ nselib/smb.lua	(working copy)
@@ -136,6 +136,7 @@
 local string = require "string"
 local table = require "table"
 local unicode = require "unicode"
+local smb2 = require "smb2"
 _ENV = stdnse.module("smb", stdnse.seeall)
 
 -- These arrays are filled in with constants at the bottom of this file
@@ -942,8 +943,9 @@
   return true, header, parameters, data
 end
 
---- Sends out <code>SMB_COM_NEGOTIATE</code>, which is typically the first SMB packet sent out.
---
+---
+-- Negotiates SMBv1 connections
+-- 
 -- Sends the following:
 -- * List of known protocols
 --
@@ -974,37 +976,30 @@
 --      * 'server_challenge' A random string used for challenge/response
 --      * 'domain'           The server's primary domain or workgroup
 --      * 'server'           The server's name
-function negotiate_protocol(smb, overrides)
+-- @param smb The SMB object associated with the connection.
+-- @param overrides Overrides table.
+-- @return (status, dialect) If status is true, the negotiated dialect in human readable form is returned as the second value.
+--                            If status is false, the error message is returned.
+---
+function negotiate_v1(smb, overrides)
   local header, parameters, data
-  local pos
-  local header1, header2, header3, header4, command, status, flags, flags2, pid_high, signature, unused, pid, mid
+  local result, err
+  local pos, header1, header2, header3, header4, command, status, flags, flags2, pid_high, signature, unused, pid, uid, tid, mid
 
-  header     = smb_encode_header(smb, command_codes['SMB_COM_NEGOTIATE'], overrides)
-
+  header = smb_encode_header(smb, command_codes['SMB_COM_NEGOTIATE'], overrides)
   -- Make sure we have overrides
   overrides = overrides or {}
 
   -- Parameters are blank
   parameters = ""
+  data = bin.pack("<CzCz", 2, (overrides['dialect'] or "NT LM 0.12"), 2, "")
 
-  -- Data is a list of strings, terminated by a blank one.
-  if(overrides['dialects'] == nil) then
-    data       = bin.pack("<CzCz", 2, (overrides['dialect'] or "NT LM 0.12"), 2, "")
-  else
-    data = ""
-    for _, v in ipairs(overrides['dialects']) do
-      data = data .. bin.pack("<Cz", 2, v)
-    end
-    data = data .. bin.pack("Cz", 2, "")
-  end
-
   -- Send the negotiate request
   stdnse.debug2("SMB: Sending SMB_COM_NEGOTIATE")
-  local result, err = smb_send(smb, header, parameters, data, overrides)
+  result, err = smb_send(smb, header, parameters, data, overrides)
   if(status == false) then
     return false, err
   end
-
   -- Read the result
   status, header, parameters, data = smb_read(smb)
   if(status ~= true) then
@@ -1012,7 +1007,6 @@
   end
 
   -- Parse out the header
-  local uid, tid
   pos, header1, header2, header3, header4, command, status, flags, flags2, pid_high, signature, unused, tid, pid, uid, mid = bin.unpack("<CCCCCICSSlSSSSS", header)
 
   -- Get the protocol version
@@ -1043,6 +1037,7 @@
   end
   -- Check if the server didn't like our requested protocol
   if(smb['dialect'] ~= 0) then
+    stdnse.debug2("Server negotiated an unknown protocol (#%d) -- aborting", smb['dialect'])
     return false, string.format("Server negotiated an unknown protocol (#%d) -- aborting", smb['dialect'])
   end
 
@@ -1118,10 +1113,78 @@
     end
   end
 
-  return true
+  stdnse.debug2("SMB_COM_NEGOTIATE got status:%s", status)
+  if status == 0 then
+    return true, overrides['dialect'] or "NT LM 0.12"
+  end
 end
 
+---
+-- Wrapper function to negotiate the protocol to use in the SMB connection.
+-- By default it attempts to negotiate with using following dialects:
+-- * NT LM 12.0 (SMBv1)
+---
+function negotiate_protocol(smb, overrides)
+  local status, dialect
+  status, dialect = negotiate_v1(smb, overrides)
+  if status then
+    return true
+  else 
+    stdnse.debug1("Couldn't negotiate a SMBv1 connection:%s", dialect)
+    -- TODO: Try SMB2/SMB3 dialects if SMBv1 failed.
+    return false, string.format("Could not negotiate a connection:%s", dialect)
+  end
+end
 
+---
+-- Returns list of supported dialects for SMBv1, SMBv2 and SMBv3.
+-- @param host       The SMB host to connect to.
+-- @param overrides [optional] Overrides for various fields.
+-- @return (status, result) If status is false, result is an error message. Otherwise, result is table of dialects
+---
+function list_dialects(host, overrides)
+  local smb2_dialects = {0x0202, 0x0210, 0x0300, 0x0302, 0x0311}
+  local supported_dialects = {}
+  local status, smb1_dialects 
+  local smbstate
+
+  -- Check for SMBv1 first
+  stdnse.debug2("Checking if SMBv1 is supported")
+  status, smbstate = start(host)
+  if(status == false) then
+    return false, smbstate
+  end
+  
+  status, smb1_dialects = negotiate_v1(smbstate, overrides)
+  if status then --Add SMBv1 as a dialect
+    table.insert(supported_dialects, smb1_dialects)
+  end
+  stop(smbstate)
+  status = false -- Finish SMBv1 and close connection
+
+  -- Check SMB2 and SMB3 dialects
+  for i, dialect in pairs(smb2_dialects) do
+    local dialect_human = stdnse.tohex(dialect, {separator = ".", group = 2})
+    -- we need a clean connection for each negotiate request
+    status, smbstate = start(host)
+    if(status == false) then
+      return false, smbstate
+    end
+    stdnse.debug2("Checking if dialect '%s' is supported", dialect_human)
+    overrides['Dialects'] = {dialect}
+    status, dialect = smb2.negotiate_v2(smbstate, overrides)
+    if status then
+      stdnse.debug2("SMB2: Dialect '%s' is supported", dialect_human)
+      table.insert(supported_dialects, dialect_human)
+    end
+    --clean smb connection
+    stop(smbstate)
+    status = false
+  end 
+
+  return true, supported_dialects
+end
+
 --- This is an internal function and should not be called externally. Use
 --  the start_session() function instead.
 local function start_session_basic(smb, log_errors, overrides)