module smtp /* * * smtp module * Created by: nedimf (07/2020) */ import net import net.openssl import encoding.base64 import strings import time import io const ( recv_size = 128 ) enum ReplyCode { ready = 220 close = 221 auth_ok = 235 action_ok = 250 mail_start = 354 } pub enum BodyType { text html } pub struct Client { mut: conn net.TcpConn ssl_conn &openssl.SSLConn = 0 reader io.BufferedReader pub: server string port int = 25 username string password string from string ssl bool starttls bool pub mut: is_open bool encrypted bool } pub struct Mail { from string to string cc string bcc string date time.Time = time.now() subject string body_type BodyType body string } // new_client returns a new SMTP client and connects to it pub fn new_client(config Client) ?&Client { if config.ssl && config.starttls { return error('Can not use both implicit SSL and STARTTLS') } mut c := &Client{ ...config } c.reconnect()? return c } // reconnect reconnects to the SMTP server if the connection was closed pub fn (mut c Client) reconnect() ? { if c.is_open { return error('Already connected to server') } conn := net.dial_tcp('$c.server:$c.port') or { return error('Connecting to server failed') } c.conn = conn if c.ssl { c.connect_ssl()? } else { c.reader = io.new_buffered_reader(reader: c.conn) } c.expect_reply(.ready) or { return error('Received invalid response from server') } c.send_ehlo() or { return error('Sending EHLO packet failed') } if c.starttls && !c.encrypted { c.send_starttls() or { return error('Sending STARTTLS failed') } } c.send_auth() or { return error('Authenticating to server failed') } c.is_open = true } // send sends an email pub fn (mut c Client) send(config Mail) ? { if !c.is_open { return error('Disconnected from server') } from := if config.from != '' { config.from } else { c.from } c.send_mailfrom(from) or { return error('Sending mailfrom failed') } c.send_mailto(config.to) or { return error('Sending mailto failed') } c.send_data() or { return error('Sending mail data failed') } c.send_body(Mail{ ...config from: from }) or { return error('Sending mail body failed') } } // quit closes the connection to the server pub fn (mut c Client) quit() ? { c.send_str('QUIT\r\n')? c.expect_reply(.close)? if c.encrypted { c.ssl_conn.shutdown()? } else { c.conn.close()? } c.is_open = false c.encrypted = false } fn (mut c Client) connect_ssl() ? { c.ssl_conn = openssl.new_ssl_conn() c.ssl_conn.connect(mut c.conn, c.server) or { return error('Connecting to server using OpenSSL failed: $err') } c.reader = io.new_buffered_reader(reader: c.ssl_conn) c.encrypted = true } // expect_reply checks if the SMTP server replied with the expected reply code fn (mut c Client) expect_reply(expected ReplyCode) ? { mut str := '' for { str = c.reader.read_line()? if str.len < 4 { return error('Invalid SMTP response: $str') } if str.runes()[3] == `-` { continue } else { break } } $if smtp_debug ? { eprintln('\n\n[RECV]') eprint(str) } if str.len >= 3 { status := str[..3].int() if ReplyCode(status) != expected { return error('Received unexpected status code $status, expecting $expected') } } else { return error('Recieved unexpected SMTP data: $str') } } [inline] fn (mut c Client) send_str(s string) ? { $if smtp_debug ? { eprintln('\n\n[SEND START]') eprint(s.trim_space()) eprintln('\n[SEND END]') } if c.encrypted { c.ssl_conn.write(s.bytes())? } else { c.conn.write(s.bytes())? } } [inline] fn (mut c Client) send_ehlo() ? { c.send_str('EHLO $c.server\r\n')? c.expect_reply(.action_ok)? } [inline] fn (mut c Client) send_starttls() ? { c.send_str('STARTTLS\r\n')? c.expect_reply(.ready)? c.connect_ssl()? } [inline] fn (mut c Client) send_auth() ? { if c.username.len == 0 { return } mut sb := strings.new_builder(100) sb.write_u8(0) sb.write_string(c.username) sb.write_u8(0) sb.write_string(c.password) a := sb.str() auth := 'AUTH PLAIN ${base64.encode_str(a)}\r\n' c.send_str(auth)? c.expect_reply(.auth_ok)? } fn (mut c Client) send_mailfrom(from string) ? { c.send_str('MAIL FROM: <$from>\r\n')? c.expect_reply(.action_ok)? } fn (mut c Client) send_mailto(to string) ? { c.send_str('RCPT TO: <$to>\r\n')? c.expect_reply(.action_ok)? } fn (mut c Client) send_data() ? { c.send_str('DATA\r\n')? c.expect_reply(.mail_start)? } fn (mut c Client) send_body(cfg Mail) ? { is_html := cfg.body_type == .html date := cfg.date.custom_format('ddd, D MMM YYYY HH:mm ZZ') nonascii_subject := cfg.subject.bytes().any(it < u8(` `) || it > u8(`~`)) mut sb := strings.new_builder(200) sb.write_string('From: $cfg.from\r\n') sb.write_string('To: <$cfg.to>\r\n') sb.write_string('Cc: <$cfg.cc>\r\n') sb.write_string('Bcc: <$cfg.bcc>\r\n') sb.write_string('Date: $date\r\n') if nonascii_subject { // handle UTF-8 subjects according RFC 1342 sb.write_string('Subject: =?utf-8?B?' + base64.encode_str(cfg.subject) + '?=\r\n') } else { sb.write_string('Subject: $cfg.subject\r\n') } if is_html { sb.write_string('Content-Type: text/html; charset=UTF-8') } else { sb.write_string('Content-Type: text/plain; charset=UTF-8') } sb.write_string('\r\n\r\n') sb.write_string(cfg.body) sb.write_string('\r\n.\r\n') c.send_str(sb.str())? c.expect_reply(.action_ok)? }