From 130baa166af2c29b71fd864083f12acf8a95f46a Mon Sep 17 00:00:00 2001
From: jtt <jtt@openbsd.org>
Date: Fri, 3 Apr 2026 10:18:58 +0000
Subject: [PATCH] smtpd: fix using modifiers with partial expansion in format
 specifiers

Nits on the manpage and ok op@
---
 usr.sbin/smtpd/mda_variables.c |  5 +++--
 usr.sbin/smtpd/smtpd.conf.5    | 12 ++++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/usr.sbin/smtpd/mda_variables.c b/usr.sbin/smtpd/mda_variables.c
index 0542f95de33..3e32fd7467f 100644
--- a/usr.sbin/smtpd/mda_variables.c
+++ b/usr.sbin/smtpd/mda_variables.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mda_variables.c,v 1.10 2024/04/23 13:34:51 jsg Exp $	*/
+/*	$OpenBSD: mda_variables.c,v 1.11 2026/04/03 10:18:58 jtt Exp $	*/
 
 /*
  * Copyright (c) 2011-2017 Gilles Chehade <gilles@poolp.org>
@@ -94,7 +94,8 @@ mda_expand_token(char *dest, size_t len, const char *token,
 			return -1;
 
 		/* token:mod_1,mod_2,mod_n -> extract modifiers */
-		mods = strchr(rbracket + 1, ':');
+		if ((mods = strchr(rbracket + 1, ':')) != NULL)
+			*mods++ = '\0';
 	} else {
 		if ((mods = strchr(rtoken, ':')) != NULL)
 			*mods++ = '\0';
diff --git a/usr.sbin/smtpd/smtpd.conf.5 b/usr.sbin/smtpd/smtpd.conf.5
index 1cdaf067c55..876ef0774ff 100644
--- a/usr.sbin/smtpd/smtpd.conf.5
+++ b/usr.sbin/smtpd/smtpd.conf.5
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: smtpd.conf.5,v 1.281 2026/03/12 07:46:08 jsg Exp $
+.\"	$OpenBSD: smtpd.conf.5,v 1.282 2026/04/03 10:18:58 jtt Exp $
 .\"
 .\" Copyright (c) 2008 Janne Johansson <jj@openbsd.org>
 .\" Copyright (c) 2009 Jacek Masiulaniec <jacekm@dobremiasto.net>
@@ -17,7 +17,7 @@
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .\"
-.Dd $Mdocdate: March 12 2026 $
+.Dd $Mdocdate: April 3 2026 $
 .Dt SMTPD.CONF 5
 .Os
 .Sh NAME
@@ -1144,6 +1144,14 @@ For example, with recipient
 .It %{rcpt:lowercase|strip} Ta expands to Dq user@example.org
 .El
 .Pp
+Modifiers and partial expansion can be used together.
+In such cases, the modifiers are applied before the partial expansion.
+For example, with sender
+.Dq owner-tech+M123456@openbsd.org :
+.Bl -column %{sender.user[6:]:strip} -offset indent
+.It %{sender.user[6:]:strip} Ta expands to Dq tech
+.El
+.Pp
 For security concerns, expanded values are sanitized and potentially
 dangerous characters are replaced with
 .Sq \&: .