--- A UPNP library based on code from upnp-info initially written by
-- Thomas Buchanan. The code was factored out from upnp-info and partly
-- re-written by Patrik Karlsson <patrik@cqure.net> in order to support
-- multicast requests.
--
-- The library supports sending UPnP requests and decoding the responses
--
-- The library contains the following classes
-- * <code>Comm</code>
-- ** A class that handles communication with the UPnP service
-- * <code>Helper</code>
-- ** The helper class wraps the <code>Comm</code> class using functions with a more descriptive name.
-- * <code>Util</code>
-- ** The <code>Util</code> class contains a number of static functions mainly used to convert and sort data.
--
-- The following code snippet queries all UPnP services on the network:
-- <code>
--   local helper = upnp.Helper:new()
--   helper:setMulticast(true)
--   return stdnse.format_output(helper:queryServices())
-- </code>
--
-- This next snippet queries a specific host for the same information:
-- <code>
--   local helper = upnp.Helper:new(host, port)
--   return stdnse.format_output(helper:queryServices())
-- </code>
--
--
-- @author "Thomas Buchanan, Patrik Karlsson <patrik@cqure.net>"

--
-- Version 0.1
--

local http = require "http"
local ipOps = require "ipOps"
local nmap = require "nmap"
local stdnse = require "stdnse"
local string = require "string"
local table = require "table"
local target = require "target"
_ENV = stdnse.module("upnp", stdnse.seeall)

Util = {

  --- Compare function used for sorting IP-addresses
  --
  -- @param a table containing first item
  -- @param b table containing second item
  -- @return true if a is less than b
  ipCompare = function(a, b)
    return ipOps.compare_ip(a, "lt", b)
  end,

}

Comm = {

  --- Creates a new Comm instance
  --
  -- @param host string containing the host name or ip
  -- @param port number containing the port to connect to
  -- @return o a new instance of Comm
  new = function( self, host, port )
    local o = {}
    setmetatable(o, self)
    self.__index = self
    o.host = host
    o.port = port
    o.mcast = false
    return o
  end,

  --- Connect to the server
  --
  -- @return status true on success, false on failure
  connect = function( self )
    if ( self.mcast ) then
      self.socket = nmap.new_socket("udp")
      self.socket:set_timeout(5000)
    else
      self.socket = nmap.new_socket()
      self.socket:set_timeout(5000)
      local status, err = self.socket:connect(self.host, self.port, "udp" )
      if ( not(status) ) then return false, err end
    end

    return true
  end,

  --- Send the UPNP discovery request to the server
  --
  -- @return status true on success, false on failure
  sendRequest = function( self )

    -- for details about the UPnP message format, see http://upnp.org/resources/documents.asp
    local payload = 'M-SEARCH * HTTP/1.1\r\n\z
    Host:239.255.255.250:1900\r\n\z
    ST:upnp:rootdevice\r\n\z
    Man:"ssdp:discover"\r\n\z
    MX:3\r\n\r\n'

    local status, err

    if ( self.mcast ) then
      status, err = self.socket:sendto( self.host, self.port, payload )
    else
      status, err = self.socket:send( payload )
    end

    if ( not(status) ) then return false, err end

    return true
  end,

  --- Receives one or multiple UPNP responses depending on whether
  -- <code>setBroadcast</code> was enabled or not.
  --
  -- The function returns the
  -- status and a response containing:
  -- * an array (table) of responses if broadcast is used
  -- * a single response if broadcast is not in use
  -- * an error message if status was false
  --
  -- @return status true on success, false on failure
  -- @return result table or string containing results or error message
  --         on failure.
  receiveResponse = function( self )
    local status, response
    local result = {}
    local host_responses = {}

    repeat
      status, response = self.socket:receive()
      if ( not(status) and #response == 0 ) then
        return false, response
      elseif( not(status) ) then
        break
      end

      local status, _, _, ip, _ = self.socket:get_info()
      if ( not(status) ) then
        return false, "Failed to retrieve socket information"
      end
      if target.ALLOW_NEW_TARGETS then target.add(ip) end

      if ( not(host_responses[ip]) ) then
        local status, output = self:decodeResponse( response )
        if ( not(status) ) then
          return false, "Failed to decode UPNP response"
        end
        output = { output }
        output.name = ip
        table.insert( result, output )
        host_responses[ip] = true
      end
    until ( not( self.mcast ) )

    if ( self.mcast ) then
      table.sort(result, Util.ipCompare)
      return true, result
    end

    if ( status and #result > 0 ) then
      return true, result[1]
    else
      return false, "Received no responses"
    end
  end,

  --- Processes a response from a upnp device
  --
  -- @param response as received over the socket
  -- @return status boolean true on success, false on failure
  -- @return response table or string suitable for output or error message if status is false
  decodeResponse = function( self, response )
    local output = {}

    if response ~= nil then
      -- We should get a response back that has contains one line for the server, and one line for the xml file location
      -- these match any combination of upper and lower case responses
      local server, location
      server = string.match(response, "[Ss][Ee][Rr][Vv][Ee][Rr]:%s*(.-)\r?\n")
      if server ~= nil then table.insert(output, "Server: " .. server ) end
      location = string.match(response, "[Ll][Oo][Cc][Aa][Tt][Ii][Oo][Nn]:%s*(.-)\r?\n")
      if location ~= nil then
        table.insert(output, "Location: " .. location )

        local v = nmap.verbosity()

        -- the following check can output quite a lot of information, so we require at least one -v flag
        if v > 0 then
          local status, result = self:retrieveXML( location )
          if status then
            table.insert(output, result)
          end
        end
      end
      if #output > 0 then
        return true, output
      else
        return false, "Could not decode response"
      end
    end
  end,

  --- Retrieves the XML file that describes the UPNP device
  --
  -- @param location string containing the location of the XML file from the UPNP response
  -- @return status boolean true on success, false on failure
  -- @return response table or string suitable for output or error message if status is false
  retrieveXML = function( self, location )
    local response
    local options = {}
    options['header'] = {}
    options['header']['Accept'] = "text/xml, application/xml, text/html"

    -- if we're in multicast mode, or if the user doesn't want us to override the IP address,
    -- just use the HTTP library to grab the XML file
    if ( self.mcast or ( not self.override ) ) then
      response = http.get_url( location, options )
    else
      -- otherwise, split the location into an IP address, port, and path name for the xml file
      local xhost, xport, xfile
      xhost = string.match(location, "http://(.-)/")
      -- check to see if the host portion of the location specifies a port
      -- if not, use port 80 as a standard web server port
      if xhost ~= nil and string.match(xhost, ":") then
        xport = string.match(xhost, ":(.*)")
        xhost = string.match(xhost, "(.*):")
      end

      -- check to see if the IP address returned matches the IP address we scanned
      if xhost ~= self.host.ip then
        stdnse.print_debug("IP addresses did not match! Found %s, using %s instead.", xhost, self.host.ip)
        xhost = self.host.ip
      end

      if xport == nil then
        xport = 80
      end

      -- extract the path name from the location field, but strip off the \r that HTTP servers return
      xfile = string.match(location, "http://.-(/.-)\013")
      if xfile ~= nil then
        response = http.get( xhost, xport, xfile, options )
      end
    end

    if response ~= nil then
      local output = {}

      -- extract information about the webserver that is handling responses for the UPnP system
      local webserver = response['header']['server']
      if webserver ~= nil then table.insert(output, "Webserver: " .. webserver) end

      -- the schema for UPnP includes a number of <device> entries, which can a number of interesting fields
      for device in string.gmatch(response['body'], "<deviceType>(.-)</UDN>") do
        local fn, mnf, mdl, nm, ver

        fn = string.match(device, "<friendlyName>(.-)</friendlyName>")
        mnf = string.match(device, "<manufacturer>(.-)</manufacturer>")
        mdl = string.match(device, "<modelDescription>(.-)</modelDescription>")
        nm = string.match(device, "<modelName>(.-)</modelName>")
        ver = string.match(device, "<modelNumber>(.-)</modelNumber>")

        if fn ~= nil then table.insert(output, "Name: " .. fn) end
        if mnf ~= nil then table.insert(output,"Manufacturer: " .. mnf) end
        if mdl ~= nil then table.insert(output,"Model Descr: " .. mdl) end
        if nm ~= nil then table.insert(output,"Model Name: " .. nm) end
        if ver ~= nil then table.insert(output,"Model Version: " .. ver) end
      end
      return true, output
    else
      return false, "Could not retrieve XML file"
    end
  end,

  --- Enables or disables multicast support
  --
  -- @param mcast boolean true if multicast is to be used, false otherwise
  setMulticast = function( self, mcast )
    assert( type(mcast)=="boolean", "mcast has to be either true or false")
    self.mcast = mcast
    local family = nmap.address_family()
    self.host = (family=="inet6" and "FF02::C" or "239.255.255.250")
    self.port = 1900
  end,

  --- Closes the socket
  close = function( self ) self.socket:close() end

}


Helper = {

  --- Creates a new helper instance
  --
  -- @param host string containing the host name or ip
  -- @param port number containing the port to connect to
  -- @return o a new instance of Helper
  new = function( self, host, port )
    local o = {}
    setmetatable(o, self)
    self.__index = self
    o.comm = Comm:new( host, port )
    return o
  end,

  --- Enables or disables multicast support
  --
  -- @param mcast boolean true if multicast is to be used, false otherwise
  setMulticast = function( self, mcast ) self.comm:setMulticast(mcast) end,

  --- Enables or disables whether the script will override the IP address is the Location URL
  --
  -- @param override boolean true if override is to be enabled, false otherwise
  setOverride = function( self, override )
    assert( type(override)=="boolean", "override has to be either true or false")
    self.comm.override = override
  end,

  --- Sends a UPnP queries and collects a single or multiple responses
  --
  -- @return status true on success, false on failure
  -- @return result table or string containing results or error message
  --         on failure.
  queryServices = function( self )
    local status, err = self.comm:connect()
    local response

    if ( not(status) ) then return false, err end

    status, err = self.comm:sendRequest()
    if ( not(status) ) then return false, err end

    status, response = self.comm:receiveResponse()
    self.comm:close()

    return status, response
  end,

}

return _ENV;
