FTPServer 3.1

-- RedNet FTP Server
protocol = "FTP"
hostname = "FTPServer"
uploadPass = ""
dirName = "files/"
programName = "File Transfer Server "
versionNumber = "3.1"
modemSide = ""

-- Find Wireless Modem
function FindModem()
 modemFound = false
 side = ""
 local pList = peripheral.getNames()
 for i = 1, #pList do
  if peripheral.getType(pList[i]) == "modem" then
   modemFound = true
   side = pList[i]
  end
 end
 if modemFound then
  return side
 else
  return false
 end
end

function WriteFile(name,filecontents)
 if fs.exists(dirName..name) then
  fs.delete(dirName..name)
 end
 file = fs.open(dirName..name,"w")
 file.write(filecontents)
 file.close()
end

function TransmitFile(id,filename)
 file = fs.open(dirName..filename,"r")
 rednet.send(id,file.readAll(),protocol)
 file.close()
end

if FindModem() == false then
 print("Modem not Found")
 return
else
 modemSide = FindModem()
end

if not fs.exists(dirName) then
 fs.makeDir(dirName)
end

rednet.open(modemSide)
rednet.host(protocol,hostname)

-- Wait for Request
term.clear()
term.setCursorPos(1,1)
print(programName..versionNumber)
while true do
id, msg = rednet.receive(protocol)
 -- If Request for List
 if msg == "LIST" then
  Flist = fs.list(dirName)
  HRlist = "\n"
   for i=1, #Flist do
    if not fs.isDir(Flist[i]) then
     HRlist = HRlist..tostring(Flist[i]).."\n"
    end
   end
  print("LIST:"..id)
  rednet.send(id,HRlist,protocol)
 end
 -- If Request to upload file
  -- REQUEST 1
 if msg == "SEND" then
  -- REQUEST 2
  id2, cPass = rednet.receive(protocol)
  if not id2 == id then
   print("CONNECTION BREAK.")
   return
  end
  if cPass == uploadPass then
   -- REQUEST 3
   rednet.send(id,"GRANTED",protocol)
   -- REQUEST 4
   local id1, pName = rednet.receive(protocol)
   -- REQUEST 5
   local id2, pContents = rednet.receive(protocol)
   WriteFile(pName,pContents)
   print("UPLOAD:"..pName..":"..id1)
  else
   rednet.send(id,"DENIED",protocol)
   print("DENY:"..id)
  end
 end

 -- If Request for File
 if fs.exists(dirName..msg) then
  rednet.send(id,"true",protocol)
  TransmitFile(id,msg)
  print("SEND:"..msg..":"..tostring(id))
 else
  rednet.send(id,"false",protocol)
 end
end