function urldecode(str) -- Decode special chars in URLs such as %20
   str = string.gsub (str, "+", " ") 
   str = string.gsub (str, "%%(%x%x)", function(h) return string.char(tonumber(h,16)) end) 
   str = string.gsub (str, "\r\n", "\n") 
   return str 
end

function url_encode(str)
   if str then
       str = string.gsub (str, "\n", "\r\n") 
       str = string.gsub (str, "([^%w ])", function (c) return string.format ("%%%02X", string.byte(c)) end) 
       str = string.gsub (str, " ", "+") 
   end 
   return str 
end

function parseURL(url)
   local ty = findpattern(url, '([a-zA-Z0-9-]*)://')
   ty = string.sub(ty, 0, string.len(ty) - 3)
   local dom = findpattern(url, '([a-zA-Z0-9-]*\.[a-zA-Z0-9-^/]*\.?[a-zA-Z0-9-]*/)', string.len(ty) + 4)
   dom = string.sub(dom, 0, string.len(dom) - 1)
   local pa = string.sub(url, string.len(ty) + string.len(dom) + 4)
   pos = -1
   while pos ~= nil do
      oldpos = pos
      pos = string.find(pa, '/', pos + 1)
   end
   local fi = string.sub(pa, oldpos + 1)
   pa = string.sub(pa, 0, string.len(pa) - string.len(fi))
   return ty, dom, pa, fi
end

function getContentLength(url)
   local urlType, urlDomain, urlPath, urlFile = parseURL(url)
   server = getIPFromDNS(urlDomain) -- get the IP for the server to connect to
   if IP=="-1" then gPrint("Error getting IP.\n") do return end end
   headersock = Socket.connect(server, 80)
   while not headersock:isConnected() do System.sleep(100) end
   bytesSent = headersock:send("HEAD "..urlPath..urlFile.." HTTP/1.0\r\n")
   bytesSent = headersock:send("User-Agent: pspRSS "..appVersion.."\r\n") -- just to be nice...
   bytesSent = headersock:send("HOST: "..urlDomain.."\r\n\r\n")
   local line, headers = " ", ""
   while headersock:isConnected() and string.find(line, "\r\n\r\n") == nil and not Controls.read():cross() do
      line = headersock:recv()
      headers = headers..line
      screen.waitVblankStart()
   end
   headersock:close()
   local redirect = string.find(headers, "HTTP.....302 Found.*")
   if redirect ~= nil then
      urlStart = string.find(headers, " ", string.find(headers, "Location[:]")) + 1
      urlEnd = string.find(headers, "\n", urlStart) - 1
      newURL = string.sub(headers, urlStart, urlEnd)
      gPrint("Feed redirects to "..newURL..".\n")
      cL, hL = getContentLength(newURL)
      return cL, hL 
   end

   local _, _, contentLength = string.find(headers, "[Cc][Oo][Nn][Tt][Ee][Nn][Tt][-][Ll][Ee][Nn][Gg][Tt][Hh][:][ ]*([0-9]*)")
   if contentLength == nil then Wlan.term() error("Invalid content length. Malformed headers?") end
   return contentLength, string.len(headers)
end

function downloadFile(url, title, defaultFilename, fix) -- This is still extremely touchy for poor connections...
   local urlType, urlDomain, urlPath, urlFile = parseURL(url)
   local contentLength, headerLength = getContentLength(url)
   local totalLength = contentLength + headerLength
   if contentLength == nil then error("Invalid content length. Malformed headers??") end
   if fix then
      if title ~= "" then rssFilename = title..".xml" -- use title (for feeds)
      elseif title == "" then rssFilename = defaultFilename -- no title, use default file name (for enclosures)
      else rssFilename = urlFile end -- use file name
   else rssFilename = defaultFilename
   end

   --server = getIPFromDNSOld(urlDomain) -- get the IP for the server to connect to
   server = getIPFromDNS(urlDomain) -- get the IP for the server to connect to
   if IP=="-1" then gPrint("Error getting IP.\n") do return end end
   --gPrint(server..":80\n")
   httpsock = Socket.connect(server, 80) -- connect to the server
   while not httpsock:isConnected() and not Controls.read():start() do System.sleep(100) end -- wait for the connection
   --gPrint("GET "..urlPath..urlFile.." HTTP/1.0\n")
   --gPrint("host: "..urlDomain.."\n")
   bytesSent = httpsock:send("GET "..urlPath..urlFile.." HTTP/1.0\r\n") -- HTTP 1.0 GET request
   bytesSent = httpsock:send("User-Agent: pspRSS "..appVersion.."\r\n") -- just to be nice...
   bytesSent = httpsock:send("host: "..urlDomain.."\r\n\r\n") -- HTTP 1.0 GET request

   filedata = ""
   while not Controls.read():start() do
      line = httpsock:recv() -- receive the next piece of the download
      filedata = filedata..line -- write the new piece
      if string.len(filedata) >= totalLength then break end
      screen.waitVblankStart()
   end

   httpsock:close()
   fileStart = headerLength + 4
   filedata = string.sub(filedata, fileStart)
   --gPrint(fixFileName(rssFilename).."\n")
   if fix then outfile = assert(io.open("feeds/"..fixFileName(rssFilename),"w")) -- open output file
   else outfile = assert(io.open(rssFilename, "w")) end
   size = string.len(filedata)
   if size ~= 0 then
      outfile:write(filedata)
      if size > 1048576 then gPrint("Saved ("..round(size/1048576, 2).." MB).\n")
      else gPrint("Saved ("..round(size/1024, 2).." KB).\n") end
   else
      gPrint("Download error.\n")
      --error("Download error.")
   end
   outfile:close()
end