Initial project import

tools/v/vlib/net/smtp/smtp.v

@@ -0,0 +1,442 @@
+module smtp
+
+/*
+*
+* smtp module
+* Created by: nedimf (07/2020)
+*/
+import net
+import net.ssl
+import encoding.base64
+import strings
+import time
+import io
+import rand
+
+const recv_size = 128
+
+enum ReplyCode {
+	ready      = 220
+	close      = 221
+	auth_ok    = 235
+	action_ok  = 250
+	mail_start = 354
+}
+
+pub enum BodyType {
+	text
+	html
+}
+
+// Message stores one body variant and optional attachments for a Mail.
+pub struct Message {
+pub:
+	body        string
+	attachments []Attachment
+}
+
+// Config stores the settings used to connect a new SMTP client.
+pub struct Config {
+pub:
+	server   string
+	port     int = 25
+	username string
+	password string
+	from     string
+	ssl      bool
+	starttls bool
+	timeout  time.Duration
+}
+
+pub struct Client {
+	Config
+mut:
+	conn     net.TcpConn
+	ssl_conn &ssl.SSLConn = unsafe { nil }
+	reader   ?&io.BufferedReader
+pub mut:
+	is_open   bool
+	encrypted bool
+}
+
+// Mail stores the message headers and MIME payload sent by Client.send.
+pub struct Mail {
+pub:
+	from        string
+	to          string
+	cc          string
+	bcc         string
+	date        time.Time = time.now()
+	subject     string
+	body_type   BodyType
+	body        string
+	attachments []Attachment
+	html        Message
+	text        Message
+	boundary    string
+}
+
+pub struct Attachment {
+pub:
+	cid      string
+	filename string
+	bytes    []u8
+}
+
+// new_client returns a new SMTP client and connects to it
+pub fn new_client(config Config) !&Client {
+	if config.ssl && config.starttls {
+		return error('Can not use both implicit SSL and STARTTLS')
+	}
+
+	mut c := &Client{
+		Config: 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')
+	}
+
+	mut conn := net.dial_tcp('${c.server}:${c.port}') or {
+		return error('Connecting to server failed')
+	}
+	if c.timeout != 0 {
+		conn.set_read_timeout(c.timeout)
+		conn.set_write_timeout(c.timeout)
+	}
+	c.conn = conn
+
+	if c.ssl || c.encrypted {
+		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
+		boundary: rand.uuid_v4()
+	}) 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 = ssl.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 or { return error('the Client.reader field is not set') }.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 unsafe { ReplyCode(status) } != expected {
+			return error('Received unexpected status code ${status}, expecting ${expected}')
+		}
+	} else {
+		return error('Received 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 ${base64.encode_str(a)}\r\n'
+	c.send_str(auth)!
+	c.expect_reply(.auth_ok)!
+}
+
+// envelope_addr extracts the bare mailbox from an address that may include a
+// display name. The SMTP envelope (`MAIL FROM:` / `RCPT TO:`) only accepts a
+// bare mailbox (RFC 5321), while `Mail.from`/`Mail.to` may also be written in
+// the RFC 5322 `Display Name <addr@example.com>` form for the message header.
+//
+// Only strip an angle-addr wrapper when the input actually ends in `>`; bare
+// mailboxes are returned unchanged. When walking for the opening `<`, quoted
+// strings are skipped so a quoted local-part like `"a<b"@example.com` is
+// preserved intact.
+fn envelope_addr(s string) string {
+	trimmed := s.trim_space()
+	if !trimmed.ends_with('>') {
+		return trimmed
+	}
+	mut in_quote := false
+	mut i := 0
+	for i < trimmed.len - 1 {
+		c := trimmed[i]
+		if c == `"` {
+			in_quote = !in_quote
+		} else if in_quote && c == `\\` && i + 1 < trimmed.len {
+			i++
+		} else if c == `<` && !in_quote {
+			return trimmed[i + 1..trimmed.len - 1]
+		}
+		i++
+	}
+	return trimmed
+}
+
+fn (mut c Client) send_mailfrom(from string) ! {
+	c.send_str('MAIL FROM:<${envelope_addr(from)}>\r\n')!
+	c.expect_reply(.action_ok)!
+}
+
+fn (mut c Client) send_mailto(to string) ! {
+	for rcpt in to.split(';') {
+		c.send_str('RCPT TO:<${envelope_addr(rcpt)}>\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) ! {
+	c.send_str(cfg.message_data())!
+	c.expect_reply(.action_ok)!
+}
+
+fn (cfg &Mail) message_data() string {
+	date := cfg.date.custom_format('ddd, D MMM YYYY HH:mm ZZ')
+	nonascii_subject := cfg.subject.bytes().any(it < u8(` `) || it > u8(`~`))
+	parts, attachments := cfg.mime_parts()
+	mut sb := strings.new_builder(200 + cfg.body.len + cfg.text.body.len + cfg.html.body.len +
+		(cfg.attachments.len + cfg.text.attachments.len + cfg.html.attachments.len) * 200)
+	sb.write_string('From: ${cfg.from}\r\n')
+	sb.write_string('To: <${cfg.to.split(';').join('>; <')}>\r\n')
+	sb.write_string('Cc: <${cfg.cc.split(';').join('>; <')}>\r\n')
+	sb.write_string('Bcc: <${cfg.bcc.split(';').join('>; <')}>\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: ${cfg.subject}\r\n')
+	}
+	if parts.len > 1 || attachments.len > 0 {
+		sb.write_string('MIME-Version: 1.0\r\n')
+	}
+
+	boundary := cfg.mime_boundary()
+	if parts.len > 1 && attachments.len > 0 {
+		alternative_boundary := '${boundary}-alternative'
+		write_multipart_header(mut sb, 'multipart/mixed', boundary)
+		write_multipart_boundary(mut sb, boundary)
+		write_multipart_header(mut sb, 'multipart/alternative', alternative_boundary)
+		for part in parts {
+			write_multipart_boundary(mut sb, alternative_boundary)
+			write_message_part(mut sb, part)
+		}
+		write_multipart_end(mut sb, alternative_boundary)
+		write_attachments(mut sb, attachments, boundary)
+	} else if parts.len > 1 {
+		write_multipart_header(mut sb, 'multipart/alternative', boundary)
+		for part in parts {
+			write_multipart_boundary(mut sb, boundary)
+			write_message_part(mut sb, part)
+		}
+		write_multipart_end(mut sb, boundary)
+	} else if attachments.len > 0 {
+		write_multipart_header(mut sb, 'multipart/mixed', boundary)
+		write_multipart_boundary(mut sb, boundary)
+		write_message_part(mut sb, parts[0])
+		write_attachments(mut sb, attachments, boundary)
+	} else {
+		write_message_part(mut sb, parts[0])
+	}
+	sb.write_string('.\r\n')
+	return sb.str()
+}
+
+struct MimePart {
+	body_type BodyType
+	body      string
+}
+
+fn (cfg &Mail) mime_parts() ([]MimePart, []Attachment) {
+	if cfg.text.body != '' || cfg.html.body != '' {
+		mut parts := []MimePart{cap: 2}
+		mut attachments := []Attachment{cap: cfg.text.attachments.len + cfg.html.attachments.len}
+		if cfg.text.body != '' {
+			parts << MimePart{
+				body_type: .text
+				body:      cfg.text.body
+			}
+		}
+		attachments << cfg.text.attachments
+		if cfg.html.body != '' {
+			parts << MimePart{
+				body_type: .html
+				body:      cfg.html.body
+			}
+		}
+		attachments << cfg.html.attachments
+		return parts, attachments
+	}
+	return [MimePart{
+		body_type: cfg.body_type
+		body:      cfg.body
+	}], cfg.attachments
+}
+
+fn (cfg &Mail) mime_boundary() string {
+	if cfg.boundary != '' {
+		return cfg.boundary
+	}
+	return 'v-smtp-boundary'
+}
+
+fn write_multipart_header(mut sb strings.Builder, multipart_type string, boundary string) {
+	sb.write_string('Content-Type: ${multipart_type}; boundary="${boundary}"\r\n\r\n')
+}
+
+fn write_multipart_boundary(mut sb strings.Builder, boundary string) {
+	sb.write_string('--${boundary}\r\n')
+}
+
+fn write_multipart_end(mut sb strings.Builder, boundary string) {
+	sb.write_string('--${boundary}--\r\n')
+}
+
+fn write_message_part(mut sb strings.Builder, part MimePart) {
+	if part.body_type == .html {
+		sb.write_string('Content-Type: text/html; charset=UTF-8\r\n')
+	} else {
+		sb.write_string('Content-Type: text/plain; charset=UTF-8\r\n')
+	}
+	sb.write_string('Content-Transfer-Encoding: base64\r\n\r\n')
+	sb.write_string(fold_base64(base64.encode_str(part.body)))
+	sb.write_string('\r\n')
+}
+
+fn write_attachments(mut sb strings.Builder, attachments []Attachment, boundary string) {
+	for attachment in attachments {
+		write_multipart_boundary(mut sb, boundary)
+		sb.write_string(attachment.to_string())
+		sb.write_string('\r\n')
+	}
+	write_multipart_end(mut sb, boundary)
+}
+
+fn (a &Attachment) to_string() string {
+	crlf := '\r\n'
+	cid := if a.cid != '' {
+		'Content-ID: <${a.cid}>${crlf}'
+	} else {
+		''
+	}
+	return 'Content-Type: application/octet-stream${crlf}${cid}Content-Transfer-Encoding: base64${crlf}Content-Disposition: attachment; filename="${a.filename}"${crlf}${crlf}${fold_base64(base64.encode(a.bytes))}'
+}
+
+fn fold_base64(encoded string) string {
+	if encoded.len <= 76 {
+		return encoded
+	}
+	mut sb := strings.new_builder(encoded.len + encoded.len / 76 * 2)
+	for start := 0; start < encoded.len; start += 76 {
+		end := if start + 76 < encoded.len { start + 76 } else { encoded.len }
+		sb.write_string(encoded[start..end])
+		if end < encoded.len {
+			sb.write_string('\r\n')
+		}
+	}
+	return sb.str()
+}