From b9d6122c53a87fc6dfce97979fa37529b412fa4d Mon Sep 17 00:00:00 2001
From: Laurent Destailleur <eldy@destailleur.fr>
Date: Sat, 18 Mar 2017 19:56:53 +0100
Subject: [PATCH] Add comments
---
htdocs/core/class/smtps.class.php | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/htdocs/core/class/smtps.class.php b/htdocs/core/class/smtps.class.php
index d16d9875fe3..b16b65e64ff 100644
--- a/htdocs/core/class/smtps.class.php
+++ b/htdocs/core/class/smtps.class.php
@@ -427,6 +427,25 @@ class SMTPs
{
if (!empty($conf->global->MAIN_MAIL_EMAIL_STARTTLS))
{
+ /*
+ The following dialog illustrates how a client and server can start a TLS STARTTLS session
+ S: <waits for connection on TCP port 25>
+ C: <opens connection>
+ S: 220 mail.imc.org SMTP service ready
+ C: EHLO mail.ietf.org
+ S: 250-mail.imc.org offers a warm hug of welcome
+ S: 250 STARTTLS
+ C: STARTTLS
+ S: 220 Go ahead
+ C: <starts TLS negotiation>
+ C & S: <negotiate a TLS session>
+ C & S: <check result of negotiation>
+ // Second pass EHLO
+ C: EHLO client-domain.com
+ S: 250-server-domain.com
+ S: 250 AUTH LOGIN
+ C: <continues by sending an SMTP command
+ */
if (!$_retVal = $this->socket_send_str('STARTTLS', 220))
{
$this->_setErr(131, 'STARTTLS connection is not supported.');
@@ -437,6 +456,8 @@ class SMTPs
$this->_setErr(132, 'STARTTLS connection failed.');
return $_retVal;
}
+ // Most server servers expect a 2nd pass of EHLO after TLS is established to get another time
+ // the answer with list of supported AUTH methods. They may differs between non STARTTLS and with STARTTLS.
if (!$_retVal = $this->socket_send_str('EHLO '.$host, '250'))
{
$this->_setErr(126, '"' . $host . '" does not support authenticated connections.');
--
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