[evolution] I#588 - Unneeded headers remain when filter forwards a message

[Milan Crha <mcrha src gnome org>]

commit 4404f135deb7237c365038943f6106684a95eaa2
Author: Milan Crha <mcrha redhat com>
Date:   Fri Aug 23 11:15:02 2019 +0200

    I#588 - Unneeded headers remain when filter forwards a message
    
    Closes https://gitlab.gnome.org/GNOME/evolution/issues/588

 src/libemail-engine/e-mail-session.c | 101 ++++++++++++++++++++++++++---------
 1 file changed, 77 insertions(+), 24 deletions(-)
---
diff --git a/src/libemail-engine/e-mail-session.c b/src/libemail-engine/e-mail-session.c
index 308e4bb20f..ab90f9af26 100644
--- a/src/libemail-engine/e-mail-session.c
+++ b/src/libemail-engine/e-mail-session.c
@@ -1550,19 +1550,23 @@ mail_session_forward_to_sync (CamelSession *session,
        ESource *source;
        ESourceRegistry *registry;
        ESourceMailIdentity *extension;
+       ESourceMailSubmission *mail_submission;
        CamelMimeMessage *forward;
        CamelStream *mem;
        CamelInternetAddress *addr;
        CamelFolder *out_folder;
        CamelMessageInfo *info;
        CamelMedium *medium;
+       CamelNameValueArray *orig_headers;
+       GString *references = NULL;
        const gchar *extension_name;
        const gchar *from_address;
        const gchar *from_name;
-       const gchar *header_name;
+       const gchar *reply_to, *message_id, *sent_folder = NULL, *transport_uid;
        gboolean success;
        gchar *subject;
        gchar *alias_name = NULL, *alias_address = NULL;
+       guint ii, len;
 
        g_return_val_if_fail (folder != NULL, FALSE);
        g_return_val_if_fail (message != NULL, FALSE);
@@ -1604,6 +1608,8 @@ mail_session_forward_to_sync (CamelSession *session,
        if (!from_name || !*from_name)
                from_name = e_source_mail_identity_get_name (extension);
 
+       reply_to = e_source_mail_identity_get_reply_to (extension);
+
        forward = camel_mime_message_new ();
 
        /* make copy of the message, because we are going to modify it */
@@ -1615,33 +1621,70 @@ mail_session_forward_to_sync (CamelSession *session,
                CAMEL_DATA_WRAPPER (forward), mem, NULL, NULL);
        g_object_unref (mem);
 
-       /* clear previous recipients */
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_TO, NULL);
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_CC, NULL);
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_BCC, NULL);
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_RESENT_TO, NULL);
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_RESENT_CC, NULL);
-       camel_mime_message_set_recipients (
-               forward, CAMEL_RECIPIENT_TYPE_RESENT_BCC, NULL);
-
        medium = CAMEL_MEDIUM (forward);
 
-       /* remove all delivery and notification headers */
-       header_name = "Disposition-Notification-To";
-       while (camel_medium_get_header (medium, header_name))
-               camel_medium_remove_header (medium, header_name);
+       message_id = camel_mime_message_get_message_id (message);
+       if (message_id && *message_id) {
+               references = g_string_sized_new (128);
+
+               if (*message_id != '<')
+                       g_string_append_c (references, '<');
+
+               g_string_append (references, message_id);
+
+               if (*message_id != '<')
+                       g_string_append_c (references, '>');
+       }
+
+       /* Remove all but content describing headers and Subject */
+       orig_headers = camel_medium_dup_headers (medium);
+       len = camel_name_value_array_get_length (orig_headers);
+
+       for (ii = 0; ii < len; ii++) {
+               const gchar *header_name = NULL, *header_value = NULL;
+
+               if (!camel_name_value_array_get (orig_headers, ii, &header_name, &header_value) || 
!header_name)
+                       continue;
+
+               if (g_ascii_strncasecmp (header_name, "Content-", 8) != 0 &&
+                   g_ascii_strcasecmp (header_name, "Subject") != 0) {
+                       if (g_ascii_strcasecmp (header_name, "References") == 0) {
+                               if (header_value && *header_value) {
+                                       if (!references)
+                                               references = g_string_sized_new (128);
+
+                                       if (references->len)
+                                               g_string_append_c (references, ' ');
+
+                                       g_string_append (references, header_value);
+                               }
+                       }
+
+                       camel_medium_remove_header (medium, header_name);
+               }
+       }
+
+       camel_name_value_array_free (orig_headers);
+
+       if (references) {
+               gchar *unfolded;
+
+               unfolded = camel_header_unfold (references->str);
+
+               if (unfolded && *unfolded)
+                       camel_medium_add_header (medium, "References", unfolded);
 
-       header_name = "Delivered-To";
-       while (camel_medium_get_header (medium, header_name))
-               camel_medium_remove_header (medium, header_name);
+               g_string_free (references, TRUE);
+               g_free (unfolded);
+       }
 
-       /* remove any X-Evolution-* headers that may have been set */
-       camel_name_value_array_free (mail_tool_remove_xevolution_headers (forward));
+       /* reply-to */
+       if (reply_to && *reply_to) {
+               addr = camel_internet_address_new ();
+               if (camel_address_unformat (CAMEL_ADDRESS (addr), reply_to) > 0)
+                       camel_mime_message_set_reply_to (forward, addr);
+               g_object_unref (addr);
+       }
 
        /* from */
        addr = camel_internet_address_new ();
@@ -1661,6 +1704,16 @@ mail_session_forward_to_sync (CamelSession *session,
        camel_mime_message_set_subject (forward, subject);
        g_free (subject);
 
+       /* store send account information */
+       mail_submission = e_source_get_extension (source, E_SOURCE_EXTENSION_MAIL_SUBMISSION);
+       if (e_source_mail_submission_get_use_sent_folder (mail_submission))
+               sent_folder = e_source_mail_submission_get_sent_folder (mail_submission);
+       transport_uid = e_source_mail_submission_get_transport_uid (mail_submission);
+
+       camel_medium_set_header (medium, "X-Evolution-Identity", e_source_get_uid (source));
+       camel_medium_set_header (medium, "X-Evolution-Fcc", sent_folder);
+       camel_medium_set_header (medium, "X-Evolution-Transport", transport_uid);
+
        /* and send it */
        info = camel_message_info_new (NULL);
        out_folder = e_mail_session_get_local_folder (