Guide to Embedded Systems Architecture - Part 4: Application layer networking protocol examples

FTP Client Pseudocode for access control commands USER and PASS

FTPConnect (string host, string login, string password) {

  TCPSocket s= new TCPSocket(FTPServer,21); // establishing a TCP connection to port 21 of the destination device   Timeout = 3 seconds; // timeout for establishing connection 3 seconds
  FTP Successful = FALSE;
  Time = 0;
  While (time < timeout) {
    read in REPLY;

    If response from recipient then {
    //login to FTP
        transmit to server ("USER "+login+ "\r\n");
        transmit to server ("PASS " + password+ "\r\n");
        read in REPLY;

        // reply 230 means user logged in, to proceed
        if REPLY not 230 {
                close TCP connection
                time = timeout;
        } else {
                time = timeout;

                FTP Successful = TRUE; }

        }

    else {
    time = time + 1;
    } // end if-then-else response from recipient
  } // end while (time < timeout)
}

FTP Client Pseudocode

// "QUIT" access command routine
FTPQuit () {

  transmit to server ("QUIT");
  read in REPLY;

  // reply 221 means server closing control connection
  if REPLY not 221 {
  // error closing connection with server
  } close TCP connection
}

// FTP Service Command Routines

  // "DELE"
  FTPDelete (string filename) {

    transmit to server ("DELE " + filename);
    read in REPLY;

    // reply 250 means requested file action Ok
    if REPLY not 250 {
    // error deleting file
    }
  }

  // "RNFR"
  FTPRenameFile (string oldfilename, string newfilename) {
  transmit to server ("RNFR " + oldfilename);
  read in REPLY;

  // reply 350 means requested file action pending further information
  if REPLY not 350 {
  // error renaming file
  }

  transmit to server ("RNTO " + newfilename);
  read in REPLY;

  // reply 250 means requested file action Ok
  if REPLY not 250 {
  // error renaming file
  }
}

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