FTPClient 3.1

-- RedNet FTP Client
protocol = "FTP"
serverhostname = "FTPServer"
programName = "File Transfer Client "
versionNumber = "3.1"
modemSide = ""

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)
 file = fs.open(name,"w")
 file.write(filecontents)
 file.close()
end

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

-- START PROGRAM
term.clear()
term.setCursorPos(1,1)
if FindModem() == false then
 print("Modem not Found")
 return
else
 modemSide = FindModem()
end

-- Attempting to connect to server.
rednet.open(modemSide)
serverid = rednet.lookup(protocol,serverhostname)
if serverid then
 print("Found Server.")
else
 print("Failed to Find Server")
 return
end

while true do
 print("'new', 'update', 'list', 'send' or 'exit'")
 ans = read()
 if ans == "exit" then
  break
 end

 -- Getting New files
 if ans == "new" then
  while true do
   print("Enter the name of the file")
   progName = read()
   if fs.exists(progName) then
     print("File already exists on device.")
    return
   end
   rednet.send(serverid,progName,protocol)
   print("Request Sent. Awaiting Response.")
   id, msg = rednet.receive(protocol)
   if id == serverid then
    if msg == "true" then
     print("File found on server. Downloading.")
     -- Start file Download.
     id2, msg2 = rednet.receive(protocol)
     WriteFile(progName,msg2)
     break
    elseif msg == "false" then
     print("File not found.")
    else
     print("Unexpected Response from server")
    end
   else
    print("Unexpected Sender")
   end
  end
 end
 -- Updating Files
 if ans == "update" then
  term.clear()
  term.setCursorPos(1,1)
  Flist = fs.list("")
  for i=1, #Flist do
   if not fs.isDir(Flist[i]) then
    rednet.send(serverid,Flist[i],protocol)
    id, msg = rednet.receive(protocol)
    if id == serverid and msg == "true" then
     print("Updating "..Flist[i])
     id2, msg2 = rednet.receive(protocol)
     fs.delete(Flist[i])
     WriteFile(Flist[i],msg2)
    end
   end
  end
  print("All files Updated.")
 end
 -- Uploading Files to Server
 if ans == "send" then
  term.clear()
  term.setCursorPos(1,1)
  print("Enter the name of the File you'd like to upload.")
  sProgName = read()
  if sProgName == "startup" or sProgName == "startup.lua" then
   print("Rename file before uploading.")
   return
  end
  if fs.exists(sProgName) then
   print("Enter Password: ")
   sPass = read()
   term.clear()
   term.setCursorPos(1,1)
   -- ANSWER 1
   rednet.send(serverid,"SEND",protocol)
   -- ANSWER 2
   rednet.send(serverid,sPass,protocol)
   -- ANSWER 3
   id, perm = rednet.receive(protocol)
   if perm == "GRANTED" then
   -- ANSWER 4
    rednet.send(serverid,sProgName,protocol)
   -- ANSWER 5
    TransmitFile(serverid,sProgName)
   elseif perm == "DENIED" then
    print("Wrong Password.")
    return
   else
    print("Unexpected Response.")
    return
   end
   print("Uploaded file: "..sProgName.." to the server.")
  else
   print("File does not exist.")
  end
 end
 -- Getting a list of all files
 if ans == "list" then
  rednet.send(serverid,"LIST",protocol)
  id, msg = rednet.receive(protocol)
  term.clear()
  term.setCursorPos(1,1)
  print("Files on Server: "..msg)
 end
end
rednet.close()