Support non-ascii SMTP user and password strings

The user and more importantly the password used when
authenticating SMTP connections MUST be encoded in utf-8, and
'base64-encode-string' requires unibyte strings, so call
'encode-coding-string' on them before base64 encoding them in
case they are multibyte strings.

This applies to the CRAM-MD5, LOGIN, and PLAIN auth methods.
XOAUTH2 access tokens are specified to contain only characters
in the range #x20-#x7E (SPC through ~), so utf-8 encoding is not
necessary.

See RFC 4616 and RFC 4954 (or their later updates).

* lisp/mail/smtpmail.el (smtpmail-try-auth-method): Encode user
and password using utf-8 before base64 encoding.

(Bug#75628)

(cherry picked from commit 745847ba8eca27e981a50ad91b628bbce35bb0f3)

diff --git a/lisp/mail/smtpmail.el b/lisp/mail/smtpmail.el
index 43291a3028baf38bffd8b25c3258759a6234a23f..db0510c7e84dfda01b813be2d4ed8efb99edb6b8 100644 (file)
--- a/lisp/mail/smtpmail.el
+++ b/lisp/mail/smtpmail.el
@@ -599,6 +599,8 @@ USER and PASSWORD should be non-nil."
     (when (eq (car ret) 334)
       (let* ((challenge (substring (cadr ret) 4))
             (decoded (base64-decode-string challenge))
+            (password (encode-coding-string password 'utf-8))
+            (user (encode-coding-string user 'utf-8))
             (hash (rfc2104-hash 'md5 64 16 password decoded))
             (response (concat user " " hash))
             ;; Osamu Yamane <yamane@green.ocn.ne.jp>:
@@ -618,8 +620,10 @@ USER and PASSWORD should be non-nil."
 (cl-defmethod smtpmail-try-auth-method
   (process (_mech (eql 'login)) user password)
   (smtpmail-command-or-throw process "AUTH LOGIN")
-  (smtpmail-command-or-throw process (base64-encode-string user t))
-  (smtpmail-command-or-throw process (base64-encode-string password t)))
+  (let ((password (encode-coding-string password 'utf-8))
+        (user (encode-coding-string user 'utf-8)))
+    (smtpmail-command-or-throw process (base64-encode-string user t))
+    (smtpmail-command-or-throw process (base64-encode-string password t))))
 
 (cl-defmethod smtpmail-try-auth-method
   (process (_mech (eql 'plain)) user password)
@@ -628,11 +632,13 @@ USER and PASSWORD should be non-nil."
   ;; violate a SHOULD in RFC 2222 paragraph 5.1.  Note that this
   ;; is not sent if the server did not advertise AUTH PLAIN in
   ;; the EHLO response.  See RFC 2554 for more info.
-  (smtpmail-command-or-throw
-   process
-   (concat "AUTH PLAIN "
-          (base64-encode-string (concat "\0" user "\0" password) t))
-   235))
+  (let ((password (encode-coding-string password 'utf-8))
+        (user (encode-coding-string user 'utf-8)))
+    (smtpmail-command-or-throw
+     process
+     (concat "AUTH PLAIN "
+             (base64-encode-string (concat "\0" user "\0" password) t))
+     235)))
 
 (cl-defmethod smtpmail-try-auth-method
   (process (_mech (eql 'xoauth2)) user password)