gpg-mail-tube: Support templates.

* tools/gpg-mail-tube.c: Include i18n.h.
(main): Call i18n.h
(only_ascii): New.
(mail_tube_encrypt): Use a template or fallback to the old version.

* doc/mail-tube.txt, doc/mail-tube.de.txt: Two standard templates.
* doc/Makefile.am (helpfiles): Add them.
--

GnuPG-bug-id: 7381

doc/Makefile.am

@@ -33,7 +33,8 @@ helpfiles = help.txt help.be.txt help.ca.txt help.cs.txt		\
             help.gl.txt help.hu.txt help.id.txt help.it.txt		\
             help.ja.txt help.nb.txt help.pl.txt help.pt.txt		\
             help.pt_BR.txt help.ro.txt help.ru.txt help.sk.txt		\
-            help.sv.txt help.tr.txt help.zh_CN.txt help.zh_TW.txt
+            help.sv.txt help.tr.txt help.zh_CN.txt help.zh_TW.txt       \
+            mail-tube.txt mail-tube.de.txt
 
 EXTRA_DIST = samplekeys.asc mksamplekeys com-certs.pem \
 	     gnupg-logo.pdf gnupg-logo.png gnupg-logo-tr.png \

doc/mail-tube.de.txt

@@ -0,0 +1,38 @@
+# mail-tube.txt -  gpg-mail-tube strings (de)        -*- default-generic -*-
+# Written in 2025 by g10 Code GmbH
+#
+# To the extent possible under law, the author(s) have dedicated all
+# copyright and related and neighboring rights to this text to the
+# public domain worldwide.  This text is distributed without any
+# warranty.  You should have received a copy of the CC0 Public Domain
+# Dedication along with this software.  If not, see
+# <https://creativecommons.org/publicdomain/zero/1.0/>.
+# SPDX-License-Identifier: CC0-1.0
+#
+# Note that this template file needs to be UTF-8 encoded.  When looking
+# for a template item, GnuPG scans the help files in the following order
+# (assuming a standard Unix layout):
+#
+#    /etc/gnupg/TEMPLATE.LL_TT.txt
+#    /etc/gnupg/TEMPLATE.LL.txt
+#    /etc/gnupg/TEMPLATE.txt
+#    /usr/share/gnupg/TEMPLATE.LL_TT.txt
+#    /usr/share/gnupg/TEMPLATE.LL.txt
+#    /usr/share/gnupg/TEMPLATE.txt
+#
+# Here TEMPLATE denotes the name of the template (e.g. "mail-tube"),
+# LL_TT denotes the full name of the current locale with the territory
+# (.e.g. "de_DE"), LL denotes just the locale name (e.g. "de").  The
+# first matching item is returned.  To put a dot or a hash mark at the
+# beginning of a text line, it needs to be prefixed with a dot and a
+# space.  A single dot may be used to terminated an entry.  Depending
+# on the template type certain variables (${NAME}) are expanded.
+# Check the man page of the respective tool.
+
+.encrypted-file-attached
+Anbei erhalten Sie eine verschlüsselte Datei.
+.
+
+.encrypted-mail-attached
+Anbei erhalten Sie eine verschlüsselte Mail.
+.

doc/mail-tube.txt

@@ -0,0 +1,38 @@
+# mail-tube.txt -  gpg-mail-tube strings (en)        -*- default-generic -*-
+# Written in 2025 by g10 Code GmbH
+#
+# To the extent possible under law, the author(s) have dedicated all
+# copyright and related and neighboring rights to this text to the
+# public domain worldwide.  This text is distributed without any
+# warranty.  You should have received a copy of the CC0 Public Domain
+# Dedication along with this software.  If not, see
+# <https://creativecommons.org/publicdomain/zero/1.0/>.
+# SPDX-License-Identifier: CC0-1.0
+#
+# Note that this template file needs to be UTF-8 encoded.  When looking
+# for a template item, GnuPG scans the help files in the following order
+# (assuming a standard Unix layout):
+#
+#    /etc/gnupg/TEMPLATE.LL_TT.txt
+#    /etc/gnupg/TEMPLATE.LL.txt
+#    /etc/gnupg/TEMPLATE.txt
+#    /usr/share/gnupg/TEMPLATE.LL_TT.txt
+#    /usr/share/gnupg/TEMPLATE.LL.txt
+#    /usr/share/gnupg/TEMPLATE.txt
+#
+# Here TEMPLATE denotes the name of the template (e.g. "mail-tube"),
+# LL_TT denotes the full name of the current locale with the territory
+# (.e.g. "de_DE"), LL denotes just the locale name (e.g. "de").  The
+# first matching item is returned.  To put a dot or a hash mark at the
+# beginning of a text line, it needs to be prefixed with a dot and a
+# space.  A single dot may be used to terminated an entry.  Depending
+# on the template type certain variables (${NAME}) are expanded.
+# Check the man page of the respective tool.
+
+.encrypted-file-attached
+Please find attached an encrypted file.
+.
+
+.encrypted-mail-attached
+Please find attached an encrypted mail.
+.

doc/tools.texi

@@ -2194,6 +2194,12 @@ The recipients must be plain mail addresses
 (e.g. @code{foo@@example.org}) and should in general list the To and
 Cc addresses contained in the mail.
 
+The tool needs to insert strings into the mails which can be
+configured using a plain text file.  The installed default files for
+English (@file{mail-tube.txt}) and German (@file{mail-tube.de.txt})
+can be copied to the system configuration directory and changed to
+local needs.  Environment variables in these texts are expanded.
+
 @mansect options
 @noindent
 @command{gpg-mail-tube} understands these options:

tools/gpg-mail-tube.c

@@ -37,6 +37,7 @@
 #include "../common/ccparray.h"
 #include "../common/mbox-util.h"
 #include "../common/zb32.h"
+#include "../common/i18n.h"
 #include "rfc822parse.h"
 #include "mime-maker.h"
 
@@ -256,6 +257,7 @@ main (int argc, char **argv)
   log_set_prefix ("gpg-mail-tube", GPGRT_LOG_WITH_PREFIX);
 
   /* Make sure that our subsystems are ready.  */
+  i18n_init();  /* Required for gnupg_get_template.  */
   init_common_subsystems (&argc, &argv);
 
   /* Parse the command line. */
@@ -369,6 +371,18 @@ main (int argc, char **argv)
 }
 
 
+/* Return true if TSRING has only ascii chacrterst or is NULL.  */
+static int
+only_ascii (const char *string)
+{
+  if (string)
+    for ( ; *string; string++)
+      if ((*string & 0x80))
+        return 0;
+  return 1;
+}
+
+
 /* This function is called by the mail parser to communicate events.
  * This callback communicates with the main function using a structure
  * passed in OPAQUE. Should return 0 or set errno and return -1. */
@@ -549,20 +563,46 @@ mail_tube_encrypt (estream_t fpin, strlist_t recipients)
   /* Output the plain or PGP/MIME boilerplate.  */
   if (opt.as_attach)
     {
-      /* FIXME: Need to have a configurable message here.  */
+      char *templ, *tmpstr;
+      const char *charset = "us-ascii";
+      const char *ctencode = "";
+
+      templ = gnupg_get_template ("mail-tube",
+                                  ct_is_text? "encrypted-file-attached"
+                                            : "encrypted-mail-attached",
+                                  (GET_TEMPLATE_SUBST_ENVVARS
+                                   | GET_TEMPLATE_CRLF));
+      if (templ && !only_ascii (templ))
+        {
+          charset = "utf-8";
+          ctencode = "Content-Transfer-Encoding: quoted-printable\r\n";
+          tmpstr = mime_maker_qp_encode (templ);
+          if (!tmpstr)
+            {
+              log_error ("QP encoding failed: %s\n",
+                         gpg_strerror (gpg_error_from_syserror ()));
+              exit (1);
+            }
+          xfree (templ);
+          templ = tmpstr;
+        }
       es_fprintf (es_stdout,
                   "\r\n"
                   "\r\n"
                   "--=-=mt-%s=-=\r\n"
-                  "Content-Type: text/plain; charset=us-ascii\r\n"
+                  "Content-Type: text/plain; charset=%s\r\n"
+                  "%s"
                   "Content-Disposition: inline\r\n"
                   "\r\n"
-                  "Please find attached an encrypted %s.\r\n"
+                  "%s"
                   "\r\n"
                   "--=-=mt-%s=-=\r\n",
                   boundary,
-                  ct_is_text? "file":"message",
+                  charset, ctencode,
+                  templ? templ
+                       : "Please find attached an encrypted file/mail.\r\n",
                   boundary);
+      xfree (templ);
       if (ct_is_text)
         es_fprintf (es_stdout,
                     "Content-Type: text/plain; charset=us-ascii\r\n"