From fa5a92c6b7847f6bafbc97d63a3935db4f175e35 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 17 Mar 2014 21:30:57 +0000
Subject: [PATCH] base.m4: Tweakable TLS parameters in `smtp' transport.

Now we can designate particular hosts as requiring TLS, with proper
certificate checking and maybe client certification.  No SMTP client
authentication yet.
---
 base.m4 | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/base.m4 b/base.m4
index 8211506..6c2dc7b 100644
--- a/base.m4
+++ b/base.m4
@@ -345,12 +345,26 @@ m4_define(<:USER_DELIVERY:>,
 	return_path_add = true:>)
 
 SECTION(transports)m4_dnl
-## A standard transport for remote delivery.  Try to do TLS, and don't worry
-## too much if it's not very secure: the alternative is sending in plaintext
-## anyway.
+## A standard transport for remote delivery.  By default, try to do TLS, and
+## don't worry too much if it's not very secure: the alternative is sending
+## in plaintext anyway.  But all of this can be overridden from the
+## `domains.conf' file.
 smtp:
 	driver = smtp
-	tls_require_ciphers = CONF_acceptable_ciphers
+	hosts_require_tls = DOMKV(tls-peer-ca, {*}{})
+	tls_certificate = DOMKV(tls-certificate, {${expand:$value}}fail)
+	tls_privatekey = DOMKV(tls-private-key, {${expand:$value}}fail)
+	tls_verify_certificates = DOMKV(tls-peer-ca, {${expand:$value}}fail)
+	tls_require_ciphers = \
+		DOMKV(tls-ciphers,
+		      {${extract {${expand:$value}} \
+				 { good = CONF_good_ciphers \
+				   any = CONF_acceptable_ciphers } \
+				 {$value} \
+				 {${expand:$value}}}} \
+		      {CONF_acceptable_ciphers})
+	## Can't set this to an expansion. :-(
+	m4_dnl tls_dh_min_bits = DOMKV(dh-min-bits, {$value}{1020})
 	tls_dh_min_bits = 1020
 	tls_tempfail_tryclear = true
 
-- 
2.11.0