[PATCH] send-email: explicitly disable authentication

[Joshua Watt <jpewhacker@gmail.com>]

It can be necessary to disable SMTP authentication by a mechanism other
than sendemail.smtpuser being undefined. For example, if the user has
sendemail.smtpuser set globally but wants to disable authentication
locally in one repository.

--smtp-auth and sendemail.smtpauth now understand the value 'none' which
means to disable authentication completely, even if an authentication
user is specified.

The value 'none' is lower case to avoid conflicts with any RFC 4422
authentication mechanisms.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
---
 Documentation/git-send-email.txt | 4 +++-
 git-send-email.perl              | 5 +++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 465a4ecbe..751a4851e 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -190,7 +190,9 @@ $ git send-email --smtp-auth="PLAIN LOGIN GSSAPI" ...
 If at least one of the specified mechanisms matches the ones advertised by the
 SMTP server and if it is supported by the utilized SASL library, the mechanism
 is used for authentication. If neither 'sendemail.smtpAuth' nor `--smtp-auth`
-is specified, all mechanisms supported by the SASL library can be used.
+is specified, all mechanisms supported by the SASL library can be used. The
+special value 'none' maybe specified to completely disable authentication
+independently of `--smtp-user`
 
 --smtp-pass[=<password>]::
 	Password for SMTP-AUTH. The argument is optional: If no
diff --git a/git-send-email.perl b/git-send-email.perl
index 2be5dac33..4a74cd350 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -82,7 +82,8 @@ sub usage {
                                      Pass an empty string to disable certificate
                                      verification.
     --smtp-domain           <str>  * The domain name sent to HELO/EHLO handshake
-    --smtp-auth             <str>  * Space-separated list of allowed AUTH mechanisms.
+    --smtp-auth             <str>  * Space-separated list of allowed AUTH mechanisms, or
+                                     "none" to disable authentication.
                                      This setting forces to use one of the listed mechanisms.
     --smtp-debug            <0|1>  * Disable, enable Net::SMTP debug.
 
@@ -1241,7 +1242,7 @@ sub smtp_host_string {
 # (smtp_user was not specified), and 0 otherwise.
 
 sub smtp_auth_maybe {
-	if (!defined $smtp_authuser || $auth) {
+	if (!defined $smtp_authuser || $auth || $smtp_auth eq "none") {
 		return 1;
 	}
 
-- 
2.17.1