This patch makes smtpd's mask-src option behave like Postfix's
smtpd_hide_client_session parameter. i.e., the "with SMTP" part of
the Received line is now stripped out as well.

This is because RFC 5322 (describing the message format) says that a
Received header can contain pretty much anything, while RFC 5321 says
that if the message is being processed in an SMTP enviroment then the
FROM clause *must* be present as well. Having a Received line saying
"with SMTP" with no FROM is a contradiction. Hence, taking it out
allows to only fulfill the laxer RFC 5322 format.

This also fixes an issue where a blank line after "Received:" was
printed instead of the from line when mask-src is active.

Prompted from a discussion on the misc opensmtpd list.
---

I didn't have the time to test this on my openbsd box, but it should be 
correct.

 usr.sbin/smtpd/smtp_session.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/usr.sbin/smtpd/smtp_session.c b/usr.sbin/smtpd/smtp_session.c
index bc7d864fc54..3be3c6e2beb 100644
--- a/usr.sbin/smtpd/smtp_session.c
+++ b/usr.sbin/smtpd/smtp_session.c
@@ -2769,22 +2769,27 @@ smtp_message_begin(struct smtp_tx *tx)
 
 	m_printf(tx, "Received: ");
 	if (!(s->listener->flags & F_MASK_SOURCE)) {
-		m_printf(tx, "from %s (%s %s%s%s)",
+		m_printf(tx, "from %s (%s %s%s%s)\n\t",
 		    s->helo,
 		    s->rdns,
 		    s->ss.ss_family == AF_INET6 ? "" : "[",
 		    ss_to_text(&s->ss),
 		    s->ss.ss_family == AF_INET6 ? "" : "]");
 	}
-	m_printf(tx, "\n\tby %s (%s) with %sSMTP%s%s id %08x",
+
+	m_printf(tx, "by %s (%s) ",
 	    s->smtpname,
-	    SMTPD_NAME,
-	    s->flags & SF_EHLO ? "E" : "",
-	    s->flags & SF_SECURE ? "S" : "",
-	    s->flags & SF_AUTHENTICATED ? "A" : "",
-	    tx->msgid);
+	    SMTPD_NAME);
 
-	if (s->flags & SF_SECURE) {
+	if (!(s->listener->flags & F_MASK_SOURCE)) {
+		m_printf(tx, "with %sSMTP%s%s ",
+		    s->flags & SF_EHLO ? "E" : "",
+		    s->flags & SF_SECURE ? "S" : "",
+		    s->flags & SF_AUTHENTICATED ? "A" : "");
+	}
+	m_printf(tx, "id %08x", tx->msgid);
+
+	if (!(s->listener->flags & F_MASK_SOURCE) && s->flags & SF_SECURE) {
 		m_printf(tx, " (%s:%s:%d:%s)",
 		    tls_conn_version(io_tls(s->io)),
 		    tls_conn_cipher(io_tls(s->io)),
-- 
2.53.0