module ftp /* basic ftp module RFC-959 https://tools.ietf.org/html/rfc959 Methods: ftp.connect(host) ftp.login(user, passw) pwd := ftp.pwd() ftp.cd(folder) dtp := ftp.pasv() ftp.dir() ftp.get(file) dtp.read() dtp.close() ftp.close() */ import net import io const ( connected = 220 specify_password = 331 logged_in = 230 login_first = 503 anonymous = 530 open_data_connection = 150 close_data_connection = 226 command_ok = 200 denied = 550 passive_mode = 227 complete = 226 ) struct DTP { mut: conn net.TcpConn reader io.BufferedReader ip string port int } fn (mut dtp DTP) read() ?[]byte { mut data := []byte{len: 1024} dtp.reader.read(mut data) ? return data } fn (dtp DTP) close() { dtp.conn.close() } struct FTP { mut: conn net.TcpConn reader io.BufferedReader buffer_size int } pub fn new() FTP { mut f := FTP{} f.buffer_size = 1024 return f } fn (mut ftp FTP) write(data string) ? { $if debug { println('FTP.v >>> $data') } ftp.conn.write('$data\r\n'.bytes()) ? } fn (mut ftp FTP) read() ?(int, string) { mut data := ftp.reader.read_line() ? $if debug { println('FTP.v <<< $data') } if data.len < 5 { return 0, '' } code := data[..3].int() if data[3] == `-` { for { data = ftp.reader.read_line() ? if data[..3].int() == code && data[3] != `-` { break } } } return code, data } pub fn (mut ftp FTP) connect(ip string) ?bool { ftp.conn = net.dial_tcp('$ip:21') ? ftp.reader = io.new_buffered_reader(reader: io.make_reader(ftp.conn)) code, _ := ftp.read() ? if code == connected { return true } return false } pub fn (mut ftp FTP) login(user string, passwd string) ?bool { ftp.write('USER $user') or { $if debug { println('ERROR sending user') } return false } mut code, _ := ftp.read() ? if code == logged_in { return true } if code != specify_password { return false } ftp.write('PASS $passwd') or { $if debug { println('ERROR sending password') } return false } code, _ = ftp.read() ? if code == logged_in { return true } return false } pub fn (mut ftp FTP) close() ? { ftp.write('QUIT') ? ftp.conn.close() } pub fn (mut ftp FTP) pwd() ?string { ftp.write('PWD') ? _, data := ftp.read() ? spl := data.split('"') // " if spl.len >= 2 { return spl[1] } return data } pub fn (mut ftp FTP) cd(dir string) ? { ftp.write('CWD $dir') or { return } mut code, mut data := ftp.read() ? match int(code) { denied { $if debug { println('CD $dir denied!') } } complete { code, data = ftp.read() ? } else {} } $if debug { println('CD $data') } } fn new_dtp(msg string) ?DTP { if !is_dtp_message_valid(msg) { return error('Bad message') } ip, port := get_host_ip_from_dtp_message(msg) conn := net.dial_tcp('$ip:$port') or { return error('Cannot connect to the data channel') } dtp := DTP{ conn: conn reader: io.new_buffered_reader(reader: io.make_reader(conn)) ip: ip port: port } return dtp } fn (mut ftp FTP) pasv() ?DTP { ftp.write('PASV') ? code, data := ftp.read() ? $if debug { println('pass: $data') } if code != passive_mode { return error('pasive mode not allowed') } dtp := new_dtp(data) ? return dtp } pub fn (mut ftp FTP) dir() ?[]string { mut dtp := ftp.pasv() or { return error('Cannot establish data connection') } ftp.write('LIST') ? code, _ := ftp.read() ? if code == denied { return error('`LIST` denied') } if code != open_data_connection { return error('Data channel empty') } list_dir := dtp.read() ? result, _ := ftp.read() ? if result != close_data_connection { println('`LIST` not ok') } dtp.close() mut dir := []string{} sdir := list_dir.bytestr() for lfile in sdir.split('\n') { if lfile.len > 1 { spl := lfile.split(' ') dir << spl[spl.len - 1] } } return dir } pub fn (mut ftp FTP) get(file string) ?[]byte { mut dtp := ftp.pasv() or { return error('Cannot stablish data connection') } ftp.write('RETR $file') ? code, _ := ftp.read() ? if code == denied { return error('Permission denied') } if code != open_data_connection { return error('Data connection not ready') } blob := dtp.read() ? dtp.close() return blob } fn is_dtp_message_valid(msg string) bool { // An example of message: // '227 Entering Passive Mode (209,132,183,61,48,218)' return msg.contains('(') && msg.contains(')') && msg.contains(',') } fn get_host_ip_from_dtp_message(msg string) (string, int) { mut par_start_idx := -1 mut par_end_idx := -1 for i, c in msg { if c == `(` { par_start_idx = i + 1 } else if c == `)` { par_end_idx = i } } data := msg[par_start_idx..par_end_idx].split(',') ip := data[0..4].join('.') port := data[4].int() * 256 + data[5].int() return ip, port }