net.smtp: add STARTTLS and implicit SSL support (#13473)

cmd/tools/modules/testing/common.v

@@ -157,6 +157,7 @@ pub fn new_test_session(_vargs string, will_compile bool) TestSession {
 		$if windows {
 			skip_files << 'examples/database/mysql.v'
 			skip_files << 'examples/database/orm.v'
+			skip_files << 'examples/smtp/mail.v' // requires OpenSSL
 			skip_files << 'examples/websocket/ping.v' // requires OpenSSL
 			skip_files << 'examples/websocket/client-server/client.v' // requires OpenSSL
 			skip_files << 'examples/websocket/client-server/server.v' // requires OpenSSL

cmd/tools/vtest-self.v

@@ -53,6 +53,7 @@ const (
 		'vlib/vweb/route_test.v',
 		'vlib/net/websocket/websocket_test.v',
 		'vlib/crypto/rand/crypto_rand_read_test.v',
+		'vlib/net/smtp/smtp_test.v',
 	]
 	skip_with_fsanitize_address   = [
 		'vlib/net/websocket/websocket_test.v',
@@ -96,6 +97,7 @@ const (
 		'vlib/net/http/server_test.v',
 		'vlib/net/http/response_test.v',
 		'vlib/builtin/js/array_test.js.v',
+		'vlib/net/smtp/smtp_test.v',
 	]
 	skip_on_linux                 = [
 		'do_not_remove',
@@ -121,6 +123,7 @@ const (
 		'vlib/vweb/route_test.v',
 		'vlib/sync/many_times_test.v',
 		'vlib/sync/once_test.v',
+		'vlib/net/smtp/smtp_test.v',
 	]
 	skip_on_non_windows           = [
 		'do_not_remove',

vlib/net/smtp/smtp.v

@@ -6,6 +6,7 @@ module smtp
 * Created by: nedimf (07/2020)
 */
 import net
+import net.openssl
 import encoding.base64
 import strings
 import time
@@ -30,16 +31,20 @@ pub enum BodyType {
 
 pub struct Client {
 mut:
-	conn   net.TcpConn
+	conn     net.TcpConn
-	reader io.BufferedReader
+	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
+	is_open   bool
+	encrypted bool
 }
 
 pub struct Mail {
@@ -55,6 +60,10 @@ pub struct Mail {
 
 // 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
 	}
@@ -71,10 +80,19 @@ pub fn (mut c Client) reconnect() ? {
 	conn := net.dial_tcp('$c.server:$c.port') or { return error('Connecting to server failed') }
 	c.conn = conn
 
-	c.reader = io.new_buffered_reader(reader: c.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
 }
@@ -98,15 +116,41 @@ pub fn (mut c Client) send(config Mail) ? {
 pub fn (mut c Client) quit() ? {
 	c.send_str('QUIT\r\n') ?
 	c.expect_reply(.close) ?
-	c.conn.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) ? {
-	bytes := io.read_all(reader: c.conn) ?
+	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
+		}
+	}
 
-	str := bytes.bytestr().trim_space()
 	$if smtp_debug ? {
 		eprintln('\n\n[RECV]')
 		eprint(str)
@@ -129,7 +173,12 @@ fn (mut c Client) send_str(s string) ? {
 		eprint(s.trim_space())
 		eprintln('\n[SEND END]')
 	}
-	c.conn.write(s.bytes()) ?
+
+	if c.encrypted {
+		c.ssl_conn.write(s.bytes()) ?
+	} else {
+		c.conn.write(s.bytes()) ?
+	}
 }
 
 [inline]
@@ -138,6 +187,13 @@ fn (mut c Client) send_ehlo() ? {
 	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 {

vlib/net/smtp/smtp_test.v

@@ -8,21 +8,14 @@ fn fn_errors(mut c smtp.Client, m smtp.Mail) bool {
 	return false
 }
 
-/*
+fn send_mail(starttls bool) {
-*
-* smtp_test
-* Created by: nedimf (07/2020)
-*/
-fn test_smtp() {
-	$if !network ? {
-		return
-	}
-
 	client_cfg := smtp.Client{
 		server: 'smtp.mailtrap.io'
+		port: 465
 		from: 'dev@vlang.io'
 		username: os.getenv('VSMTP_TEST_USER')
 		password: os.getenv('VSMTP_TEST_PASS')
+		starttls: starttls
 	}
 	if client_cfg.username == '' && client_cfg.password == '' {
 		eprintln('Please set VSMTP_TEST_USER and VSMTP_TEST_PASS before running this test')
@@ -87,3 +80,46 @@ fn test_smtp() {
 	}
 	assert true
 }
+
+/*
+*
+* smtp_test
+* Created by: nedimf (07/2020)
+*/
+fn test_smtp() {
+	$if !network ? {
+		return
+	}
+
+	// Test sending without STARTTLS
+	send_mail(false)
+
+	// Sleep for 10 seconds to reset the Mailtrap rate limit counter
+	// See: https://help.mailtrap.io/article/44-features-and-limits#rate-limit
+	time.sleep(10000 * time.millisecond)
+
+	// Test with STARTTLS
+	send_mail(true)
+}
+
+fn test_smtp_implicit_ssl() {
+	$if !network ? {
+		return
+	}
+
+	client_cfg := smtp.Client{
+		server: 'smtp.gmail.com'
+		port: 465
+		from: ''
+		username: ''
+		password: ''
+		ssl: true
+	}
+
+	mut client := smtp.new_client(client_cfg) or {
+		assert false
+		return
+	}
+
+	assert client.is_open && client.encrypted
+}