description = [[
Decodes the VSNNUM version number from an Oracle TNS listener.
]]

local shortport = require "shortport"
local nmap = require "nmap"
local comm = require "comm"
local stdnse = require "stdnse"
local string = require "string"
local U = require "lpeg-utility"

author = "Daniel Miller"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"version", "safe"}

portrule = function (host, port)
  return (
    -- -sV has an actual version for this, no need to send more probes and decode.
    not (port.version and port.version.version and port.version.version ~= "")
    -- Otherwise, normal checking for port numbers etc.
    and shortport.version_port_or_service({1521,1522,1523}, "oracle-tns")(host, port)
    )
end

-- Lifted from nmap-service-probes
-- TODO: Figure out if we can send a better probe than this. We might need to
--       send ADDRESS, CID, etc.
local oracle_tns_probe = "\0Z\0\0\x01\0\0\0\x016\x01,\0\0\x08\0\x7F\xFF\x7F\x08\0\0\0\x01\0 \0:\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\04\xE6\0\0\0\x01\0\0\0\0\0\0\0\0(CONNECT_DATA=(COMMAND=version))"

local ERR_CODES = {
  ["1189"] = "unauthorized",
  ["1194"] = "insecure transport",
  ["12504"] = "requires service name",
  ["12514"] = "unknown service name",
}

local function decode_vsnnum (vsnnum)
  local hex = stdnse.tohex(tonumber(vsnnum))
  local maj, min, a, b, c = string.unpack("c1 c1 c2 c1 c2", hex)
  return string.format("%d.%d.%d.%d.%d",
    tonumber(maj, 16),
    tonumber(min, 16),
    tonumber(a, 16),
    tonumber(b, 16),
    tonumber(c, 16)
    )
end

action = function (host, port)
  local response
  -- Did the service engine already do the hard work?
  if port.version and port.version.service_fp then
    -- Probes sent, replies received, but no match.
    response = U.get_response(port.version.service_fp, "oracle-tns")
  end

  if not response then
    -- Have to send the probe ourselves
    local status
    status, response = comm.exchange(host, port, oracle_tns_probe)
    if not status then
      stdnse.debug1("Couldn't get a response: %s", response)
      return nil
    end
  end

  local vsnnum = response and response:match("%(VSNNUM=(%d+)%)", 12)
  port.version = port.version or {}
  if vsnnum then
    local version = decode_vsnnum(vsnnum)
    port.version.product = "Oracle TNS listener"
    port.version.version = version
    local cpes = port.version.cpe or {}
    cpes[#cpes+1] = "cpe:/a:oracle:database_server:" .. version
    port.version.cpe = cpes
  end

  local errno = response and response:match("%(ERR=(%d+)%)", 12)
  if errno then
    port.version.extrainfo = ERR_CODES[errno] or ("error: "..errno)
  end

  if vsnnum or errno then
    nmap.set_port_version(host, port, "hardmatched")
  end
end