[PATCH] b4: allow using xoauth2/bearer token to authenticate to SMTP servers

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Allow using XOAUTH2 as an authentication protocol and assume that when
XOAUTH2 is specified the password is actually a bearer token (typically
not stored in the config but rather returned via "git credentials".

Recognize "oauth", "oauth2" as aliases for "xoauth2".

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 src/b4/__init__.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/b4/__init__.py b/src/b4/__init__.py
index eab290b..9a5d25b 100644
--- a/src/b4/__init__.py
+++ b/src/b4/__init__.py
@@ -4312,8 +4312,8 @@ def get_smtp(dryrun: bool = False) -> Tuple[Union[smtplib.SMTP, smtplib.SMTP_SSL
 
         # If we got to this point, we should do authentication,
         # unless smtpauth is set to a special "none" value
-        smtpauth = str(sconfig.get('smtpauth', ''))
-        if smtpauth.lower() == 'none':
+        smtpauth = str(sconfig.get('smtpauth', '')).lower()
+        if smtpauth == 'none':
             return smtp, fromaddr
 
         auser = str(sconfig.get('smtpuser', ''))
@@ -4331,7 +4331,11 @@ def get_smtp(dryrun: bool = False) -> Tuple[Union[smtplib.SMTP, smtplib.SMTP_SSL
                 raise smtplib.SMTPException('No password specified for connecting to %s', server)
         if auser and apass:
             # Let any exceptions bubble up
-            smtp.login(auser, apass)
+            if smtpauth in ('oauth', 'oauth2', 'xoauth2'):
+                auth_str = f'user={auser}\x01auth=Bearer {apass}\x01\x01'
+                smtp.auth('XOAUTH2', lambda: auth_str)
+            else:
+                smtp.login(auser, apass)
     else:
         # We assume you know what you're doing if you don't need encryption
         smtp = smtplib.SMTP(server, port)
-- 
2.53.0.473.g4a7958ca14-goog