From 1dc79aa8fc4f9cfd675c5c2ad744c9d85a185515 Mon Sep 17 00:00:00 2001
From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Mon, 30 Aug 2021 02:03:15 +0200
Subject: [PATCH] Make epg use rfc6068 for decoding %-encoded strings

* lisp/epg.el (epg--decode-percent-escape-as-utf-8): Make obsolete
and adjust callers.
(epg--decode-hexstring): Ditto.

* lisp/mail/rfc6068.el (rfc6068-unhexify-string): Allow returning
non-decoded octets (bug#39689).
---
 lisp/epg.el          | 13 ++++++++-----
 lisp/mail/rfc6068.el | 29 ++++++++++++++++++-----------
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/lisp/epg.el b/lisp/epg.el
index 9d6295594fd..67d723b961b 100644
--- a/lisp/epg.el
+++ b/lisp/epg.el
@@ -25,6 +25,7 @@
 ;;; Prelude
 
 (require 'epg-config)
+(require 'rfc6068)
 (eval-when-compile (require 'cl-lib))
 
 (define-error 'epg-error "GPG error")
@@ -432,7 +433,7 @@ callback data (if any)."
      (and user-id
 	  (concat " "
 		  (if (stringp user-id)
-		      (epg--decode-percent-escape-as-utf-8 user-id)
+		      (rfc6068-unhexify-string user-id)
 		    (epg-decode-dn user-id))))
      (and (epg-signature-validity signature)
 	  (format " (trust %s)"  (epg-signature-validity signature)))
@@ -777,7 +778,7 @@ callback data (if any)."
 	     (user-id (match-string 2 string))
 	     (entry (assoc key-id epg-user-id-alist)))
 	(condition-case nil
-	    (setq user-id (epg--decode-percent-escape-as-utf-8 user-id))
+	    (setq user-id (rfc6068-unhexify-string user-id))
 	  (error))
 	(if entry
 	    (setcdr entry user-id)
@@ -906,7 +907,7 @@ callback data (if any)."
 	(condition-case nil
 	    (if (eq (epg-context-protocol context) 'CMS)
 		(setq user-id (epg-dn-from-string user-id))
-	      (setq user-id (epg--decode-percent-escape-as-utf-8 user-id)))
+	      (setq user-id (rfc6068-unhexify-string user-id)))
 	  (error))
 	(if entry
 	    (setcdr entry user-id)
@@ -1182,7 +1183,7 @@ callback data (if any)."
 	     (user-id (match-string 2 string))
 	     (entry (assoc key-id epg-user-id-alist)))
 	(condition-case nil
-	    (setq user-id (epg--decode-percent-escape-as-utf-8 user-id))
+	    (setq user-id (rfc6068-unhexify-string user-id))
 	  (error))
 	(if entry
 	    (setcdr entry user-id)
@@ -2061,9 +2062,11 @@ If you are unsure, use synchronous version of this function
     string))
 
 (defun epg--decode-percent-escape-as-utf-8 (string)
+  (declare (obsolete rfc6068-unhexify-string "28.1"))
   (decode-coding-string (epg--decode-percent-escape string) 'utf-8))
 
 (defun epg--decode-hexstring (string)
+  (declare (obsolete rfc6068-unhexify-string "28.1"))
   (let ((index 0))
     (while (eq index (string-match "[[:xdigit:]][[:xdigit:]]" string index))
       (setq string (replace-match (string (string-to-number
@@ -2114,7 +2117,7 @@ The return value is an alist mapping from types to values."
 		value (epg--decode-quotedstring (match-string 0 string)))
 	(if (eq index (string-match "#\\([[:xdigit:]]+\\)" string index))
 	    (setq index (match-end 0)
-		  value (epg--decode-hexstring (match-string 1 string)))
+		  value (rfc6068-unhexify-string (match-string 1 string) t))
 	  (if (eq index (string-match "\"\\([^\\\"]\\|\\\\.\\)*\""
 				      string index))
 	      (setq index (match-end 0)
diff --git a/lisp/mail/rfc6068.el b/lisp/mail/rfc6068.el
index 6198342116e..34fd7b5df4e 100644
--- a/lisp/mail/rfc6068.el
+++ b/lisp/mail/rfc6068.el
@@ -22,17 +22,24 @@
 ;;; Commentary:
 ;;; Code:
 
-(defun rfc6068-unhexify-string (string)
-  "Unhexify STRING -- e.g. `hello%20there' -> `hello there'."
-  (decode-coding-string
-   (with-temp-buffer
-     (set-buffer-multibyte nil)
-     (insert string)
-     (goto-char (point-min))
-     (while (re-search-forward "%\\([[:xdigit:]]\\{2\\}\\)" nil t)
-       (replace-match (string (string-to-number (match-string 1) 16)) t t))
-     (buffer-string))
-   'utf-8))
+(defun rfc6068-unhexify-string (string &optional inhibit-decode)
+  "Unhexify STRING -- e.g. `hello%20there' -> `hello there'.
+STRING is assumed to be a percentage-encoded utf-8 string.
+
+If INHIBIT-DECODE is non-nil, return the resulting raw byte
+string instead of decoding as utf-8."
+  (let ((string
+         (with-temp-buffer
+           (set-buffer-multibyte nil)
+           (insert string)
+           (goto-char (point-min))
+           (while (re-search-forward "%\\([[:xdigit:]]\\{2\\}\\)" nil t)
+             (replace-match (string (string-to-number (match-string 1) 16))
+                            t t))
+           (buffer-string))))
+    (if inhibit-decode
+        string
+      (decode-coding-string string 'utf-8))))
 
 (defun rfc6068-parse-mailto-url (mailto-url)
   "Parse MAILTO-URL, and return an alist of header-name, header-value pairs.
-- 
2.39.2