auth

-- cs authentication
-- prompt for login on startup

-- specify the authentication server details
authServer = "none"
authProtocol = "auth"

-- specify the local credentials
localuser = "admin"
localpass = "admin"

-- used to validate credentials with server
function validateCredentialsRemote(id, user, pass)
  -- detect and open modems
  for k, v in pairs(redstone.getSides()) do
    if peripheral.getType(v) == "modem" then
      rednet.open(v)
    end
  end
  -- send the credentials to the authentication server
  local credentials = {user, pass}
  rednet.send(id, credentials, authProtocol)
  -- receive a message from the server
  local source, message = rednet.receive(authProtocol, 10)
  if source == id and message == "SUCCESS" then
    return true
  elseif source == id and message == "FAILURE" then
    return false, "Invalid credentials."
  else
    return false, "Could not connect to the server."
  end
end

-- used to validate credentials locally
function validateCredentialsLocal(user, pass)
  if user == localuser and pass == localpass then
    return true
  else
    return false, "Invalid credentials."
  end
end

-- continuously check for logins
while true do
  -- clear the terminal
  term.clear()
  term.setCursorPos(1, 1)
  -- print a welcome message
  print("PROPERTY OF CS FACTION\n")

  -- prompt the user for a username and password
  write("username> ")
  local user = read()
  write("password> ")
  local pass = read()

  -- validate with a remote server or locally
  local valid, e

  -- use the authentication server if specified
  if authServer ~= "none" then
    -- lookup the id of the authentication server
    local id = rednet.lookup(authProtocol, authServer)
    -- validate using the authentication server
    if id ~= nil then
      print("\nConnecting to authentication server...")
      valid, e = validateCredentialsRemote(id, user, pass_
    else
      print("\nAuthentication server not found. Using local credentials...")
      valid, e = validateCredentialsLocal(user, pass)
    end

  -- use local credentials if an authentication server is not specified
  else
    valid, e = validateCredentialsLocal(user, pass)
  end

  -- launch a shell if the credentials are valid
  if valid == true then
    term.clear()
    term.setCursorPos(1, 1)
    shell.run("/rom/programs/shell")
  else
    print(e.." Press any key to continue...")
    read()
  end
end