From 3bc34894be2f45093f21f0ba1c10c42906c9ec27 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Pierre-Elliott=20B=C3=A9cue?= <becue@crans.org>
Date: Tue, 30 Aug 2016 22:49:19 +0200
Subject: [PATCH] Replies possible with X-Original-To: header

 Adds a reply_with_xorig boolean parameter. When set, it allows to
 reply to emails using X-Original-To: header email address. This will
 work provided reverse_realname is not active or failed to find an
 appropriate From: to provide. The option, if fast_reply is disabled,
 also provides a From: prompt when hitting reply. By default it'll be
 filled with the extracted address.
---
 imap/message.c |  2 +-
 init.h         | 10 ++++++++++
 mutt.h         |  2 ++
 muttlib.c      |  1 +
 parse.c        |  6 ++++++
 send.c         | 25 +++++++++++++++++++++++++
 6 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/imap/message.c b/imap/message.c
index 8211d3a11..3e8b555d5 100644
--- a/imap/message.c
+++ b/imap/message.c
@@ -69,7 +69,7 @@ int imap_read_headers (IMAP_DATA* idata, int msgbegin, int msgend)
   int rc, mfhrc, oldmsgcount;
   int fetchlast = 0;
   int maxuid = 0;
-  static const char * const want_headers = "DATE FROM SUBJECT TO CC MESSAGE-ID REFERENCES CONTENT-TYPE CONTENT-DESCRIPTION IN-REPLY-TO REPLY-TO LINES LIST-POST X-LABEL X-KEYWORDS X-MOZILLA-KEYS KEYWORDS";
+  static const char * const want_headers = "DATE FROM SUBJECT TO CC MESSAGE-ID REFERENCES CONTENT-TYPE CONTENT-DESCRIPTION IN-REPLY-TO REPLY-TO LINES LIST-POST X-LABEL X-KEYWORDS X-MOZILLA-KEYS KEYWORDS X-ORIGINAL-TO";
   progress_t progress;
   int retval = -1;
 
diff --git a/init.h b/init.h
index dff4dd04b..f38abfa71 100644
--- a/init.h
+++ b/init.h
@@ -2762,6 +2762,16 @@ struct option_t MuttVars[] = {
   ** header field to the list address and you want to send a private
   ** message to the author of a message.
   */
+  { "reply_with_xorig", DT_BOOL, R_NONE, OPTREPLYWITHXORIG, 0 },
+  /*
+  ** .pp
+  ** This variable provides a toggle. When active, the From: header will be
+  ** extracted from the current mail's `X-Original-To:' header. This setting
+  ** does not have precedence over ``$reverse_realname''.
+  ** .pp
+  ** Assuming `fast_reply' is disabled, this option will prompt the user with a
+  ** prefilled From: header.
+  */
   { "resolve",		DT_BOOL, R_NONE, OPTRESOLVE, 1 },
   /*
   ** .pp
diff --git a/mutt.h b/mutt.h
index e7ecdffdd..ea9f6287b 100644
--- a/mutt.h
+++ b/mutt.h
@@ -473,6 +473,7 @@ enum
   OPTREFLOWSPACEQUOTES,
   OPTREFLOWTEXT,
   OPTREPLYSELF,
+  OPTREPLYWITHXORIG,
   OPTRESOLVE,
   OPTRESUMEDRAFTFILES,
   OPTRESUMEEDITEDDRAFTFILES,
@@ -678,6 +679,7 @@ typedef struct envelope
   ADDRESS *sender;
   ADDRESS *reply_to;
   ADDRESS *mail_followup_to;
+  ADDRESS *x_original_to;
   char *list_post;		/* this stores a mailto URL, or nothing */
   char *subject;
   char *real_subj;		/* offset of the real subject */
diff --git a/muttlib.c b/muttlib.c
index 41de6385a..067be7765 100644
--- a/muttlib.c
+++ b/muttlib.c
@@ -780,6 +780,7 @@ void mutt_merge_envelopes(ENVELOPE* base, ENVELOPE** extra)
   MOVE_ELEM(supersedes);
   MOVE_ELEM(date);
   MOVE_ELEM(labels);
+  MOVE_ELEM(x_original_to);
   if (!base->refs_changed)
   {
     MOVE_ELEM(references);
diff --git a/parse.c b/parse.c
index 2d5d8b910..92da61e36 100644
--- a/parse.c
+++ b/parse.c
@@ -1331,6 +1331,11 @@ int mutt_parse_rfc822_line (ENVELOPE *e, HEADER *hdr, char *line, char *p, short
       matched = 1;
     }
 #endif
+    else if (!ascii_strcasecmp (line + 1, "-original-to"))
+    {
+      e->x_original_to = rfc822_parse_adrlist (e->x_original_to, p);
+      matched = 1;
+    }
 
     default:
     break;
@@ -1548,6 +1553,7 @@ ENVELOPE *mutt_read_rfc822_header (FILE *f, HEADER *hdr, short user_hdrs,
     rfc2047_decode_adrlist (e->mail_followup_to);
     rfc2047_decode_adrlist (e->return_path);
     rfc2047_decode_adrlist (e->sender);
+    rfc2047_decode_adrlist (e->x_original_to);
 
     if (e->subject)
     {
diff --git a/send.c b/send.c
index 007218fbb..61356eaf8 100644
--- a/send.c
+++ b/send.c
@@ -265,6 +265,10 @@ static int edit_envelope (ENVELOPE *en, int flags)
       return (-1);
     if (option (OPTASKBCC) && edit_address (&en->bcc, "Bcc: ") == -1)
       return (-1);
+    if (option (OPTREPLYWITHXORIG) &&
+	(flags & (SENDREPLY|SENDLISTREPLY|SENDGROUPREPLY)) &&
+	(edit_address (&en->from, "From: ") == -1))
+      return (-1);
   }
 
   if (en->subject)
@@ -1400,8 +1404,29 @@ ci_send_message (int flags,		/* send mode */
      * have their aliases expanded.
      */
 
+    if (msg->env->from)
+        dprint (5, (debugfile, "ci_send_message: msg->env->from before set_reverse_name: %s\n", msg->env->from->mailbox));
     msg->env->from = set_reverse_name (cur->env);
   }
+  if (cur && option (OPTREPLYWITHXORIG) && !(flags & (SENDPOSTPONED|SENDRESEND|SENDFORWARD)))
+  {
+    /* We shouldn't have to worry about freeing `msg->env->from' before
+     * setting it here since this code will only execute when doing some
+     * sort of reply. The pointer will only be set when using the -H command
+     * line option.
+     *
+     * If there is already a from address recorded in `msg->env->from',
+     * then it theoretically comes from OPTREVNAME handling, and we don't use
+     * the `X-Orig-To header'.
+     */
+    if (cur->env->x_original_to && !msg->env->from)
+    {
+      msg->env->from = cur->env->x_original_to;
+      /* Not more than one from address */
+      msg->env->from->next = NULL;
+      dprint (5, (debugfile, "ci_send_message: msg->env->from extracted from X-Original-To: header: %s\n", msg->env->from->mailbox));
+    }
+  }
 
   if (! (flags & (SENDPOSTPONED|SENDRESEND)) &&
       ! ((flags & SENDDRAFTFILE) && option (OPTRESUMEDRAFTFILES)))
-- 
2.40.0