Add script tn3270-screen and tn3270.lua. See #554

CHANGELOG

@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE] Script tn3270-screen shows the login screen from mainframe TN3270
+  Telnet services, including any hidden fields. The script is accompanied by
+  the new tn3270 library. [Soldier of Fortran]
+
 o [NSE] Script nje-pass-brute brute-forces the password to a NJE node, given a
   valid RHOST and OHOST. Helpfully, nje-node-brute can now brute force both of
   those values. [Soldier of Fortran]

scripts/script.db

@@ -517,6 +517,7 @@ Entry { filename = "telnet-encryption.nse", categories = { "discovery", "safe",
 Entry { filename = "telnet-ntlm-info.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "tftp-enum.nse", categories = { "discovery", "intrusive", } }
 Entry { filename = "tls-nextprotoneg.nse", categories = { "default", "discovery", "safe", } }
+Entry { filename = "tn3270-screen.nse", categories = { "discovery", "safe", } }
 Entry { filename = "tor-consensus-checker.nse", categories = { "external", "safe", } }
 Entry { filename = "traceroute-geolocation.nse", categories = { "discovery", "external", "safe", } }
 Entry { filename = "unittest.nse", categories = { "safe", } }

scripts/tn3270-screen.nse

@@ -0,0 +1,104 @@
+local stdnse = require "stdnse"
+local shortport = require "shortport"
+local tn3270 = require "tn3270"
+
+description = [[
+Connects to a tn3270 'server' and returns the screen.
+]]
+
+---
+-- @usage
+-- nmap --script tn3270-info,tn3270_screen <host>
+--
+-- @output
+-- PORT     STATE  SERVICE         VERSION
+-- 23/tcp   open   tn3270          Telnet TN3270
+-- | tn3270-screen:
+-- |  Mainframe Operating System                              z/OS V1.6
+-- |          FFFFF  AAA  N   N      DDDD  EEEEE      ZZZZZ H   H  III
+-- |          F     A   A NN  N      D   D E             Z  H   H   I
+-- |          FFFF  AAAAA N N N      D   D EEEE         Z   HHHHH   I
+-- |          F     A   A N  NN      D   D E           Z    H   H   I
+-- |          F     A   A N   N      DDDD  EEEEE      ZZZZZ H   H  III
+-- |
+-- |                         ZZZZZ      / OOOOO  SSSS
+-- |                            Z      /  O   O S
+-- |                           Z      /   O   O  SSS
+-- |                          Z      /    O   O     S
+-- |                         ZZZZZ  /     OOOOO SSSS
+-- |
+-- |                   Welcome to Fan DeZhi Mainframe System!
+-- |
+-- |                       Support: http://zos.efglobe.com
+-- |          TSO      - Logon to TSO/ISPF        NETVIEW  - Netview System
+-- |          CICS     - CICS System              NVAS     - Netview Access
+-- |          IMS      - IMS System               AOF      - Netview Automation
+-- |
+-- | Enter your choice==>
+-- | Hi! Enter one of above commands in red.
+-- |
+-- |_Your IP(10.10.10.375   :64199), SNA LU(        )       05/30/15 13:33:37
+--
+-- @args tn3270.commands a semi-colon separated list of commands you want to
+--                       issue before printing the screen
+--
+--
+-- @changelog
+-- 2015-05-30 - v0.1 - created by Soldier of Fortran
+-- 2015-11-14 - v0.2 - added commands argument
+--
+
+author = "Philip Young aka Soldier of Fortran"
+license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
+categories = {"safe", "discovery"}
+-- XXX Is this a real script?
+--dependencies = {"tn3270-info"}
+
+portrule = shortport.port_or_service({23,992}, {"tn3270"})
+
+local hidden_field_mt = {
+  __tostring = function(t)
+    return ("(%d, %d): %s"):format(t.row, t.col, t.field)
+  end,
+}
+
+action = function(host, port)
+  local commands = stdnse.get_script_args(SCRIPT_NAME .. '.commands')
+  local t = tn3270.Telnet:new()
+  local status, err = t:initiate(host,port)
+  if not status then
+    stdnse.debug("Could not initiate TN3270: %s", err )
+    return
+  else
+    if commands then
+      local run = stdnse.strsplit(";%s*", commands)
+      for i = 1, #run do
+        stdnse.debug(1,"Issuing Command (#%s of %s): %s", i, #run ,run[i])
+        t:send_cursor(run[i])
+        t:get_all_data()
+        t:get_screen_debug()
+      end
+    end
+    status = t:get_all_data()
+    local hidden
+    if t:any_hidden() then
+      hidden = {}
+      local hidden_buggers = t:hidden_fields()
+      local hidden_locs = t:hidden_fields_location()
+      for i = 1, #hidden_buggers do
+        local j = i*2 - 1
+        local field = {
+          field = hidden_buggers[i],
+          row = t:BA_TO_ROW(hidden_locs[j]),
+          col = t:BA_TO_COL(hidden_locs[j]),
+        }
+        setmetatable(field, hidden_field_mt)
+        hidden[i] = field
+      end
+    end
+    local out = stdnse.output_table()
+    out.screen = t:get_screen()
+    out["hidden fields"] = hidden
+    return out
+  end
+end