[evolution] Colorize insecure parts as 'bad' in otherwise secure mail

[Milan Crha <mcrha src gnome org>]

commit dbeb73ca0d110c5ea464e77024b3c0691c3ffcca
Author: Milan Crha <mcrha redhat com>
Date:   Tue Feb 26 17:35:41 2019 +0100

    Colorize insecure parts as 'bad' in otherwise secure mail
    
    When a multipart message contains signed/encrypted (secure) parts together
    with unsigned/unencrypted (insecure) parts, colorize the insecure parts
    as 'bad' (red border), for a brief distinguishable way of the parts.
    
    Related to https://gitlab.gnome.org/GNOME/evolution/issues/203

 src/em-format/e-mail-part-utils.c | 74 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
---
diff --git a/src/em-format/e-mail-part-utils.c b/src/em-format/e-mail-part-utils.c
index 6b2c17f1cb..588b65afea 100644
--- a/src/em-format/e-mail-part-utils.c
+++ b/src/em-format/e-mail-part-utils.c
@@ -66,6 +66,80 @@ e_mail_part_get_frame_security_style (EMailPart *part)
        flags = e_mail_part_get_validity_flags (part);
 
        if (flags == E_MAIL_PART_VALIDITY_NONE) {
+               EMailPartList *part_list;
+
+               part_list = e_mail_part_ref_part_list (part);
+
+               if (part_list) {
+                       GQueue queue = G_QUEUE_INIT;
+                       GList *link;
+                       GSList *stack = NULL;
+                       gchar *end_partid = NULL;
+                       gboolean any_secure = FALSE;
+
+                       e_mail_part_list_queue_parts (part_list, NULL, &queue);
+
+                       for (link = g_queue_peek_head_link (&queue); link; link = g_list_next (link)) {
+                               EMailPart *lpart = link->data;
+
+                               if (lpart == part) {
+                                       GList *start = link;
+
+                                       /* Find which message this part belongs to */
+                                       while (start = g_list_previous (start), start) {
+                                               lpart = start->data;
+                                               if (e_mail_part_id_has_suffix (lpart, ".rfc822") ||
+                                                   e_mail_part_id_has_suffix (lpart, ".headers")) {
+                                                       end_partid = g_strconcat (e_mail_part_get_id (lpart), 
".end", NULL);
+                                                       break;
+                                               }
+                                       }
+
+                                       link = start ? start : link;
+                                       break;
+                               }
+                       }
+
+                       for (; link && !any_secure && end_partid; link = g_list_next (link)) {
+                               EMailPart *lpart = link->data;
+
+                               if (!lpart)
+                                       continue;
+
+                               if (g_strcmp0 (end_partid, e_mail_part_get_id (lpart)) == 0) {
+                                       g_free (end_partid);
+                                       end_partid = NULL;
+
+                                       if (stack) {
+                                               end_partid = stack->data;
+                                               stack = g_slist_remove (stack, end_partid);
+                                       }
+
+                                       continue;
+                               }
+
+                               if (e_mail_part_id_has_suffix (lpart, ".rfc822")) {
+                                       stack = g_slist_prepend (stack, end_partid);
+                                       end_partid = g_strconcat (e_mail_part_get_id (lpart), ".end", NULL);
+                               }
+
+                               if (!stack)
+                                       any_secure = e_mail_part_get_validity_flags (lpart) != 
E_MAIL_PART_VALIDITY_NONE;
+                       }
+
+                       while (!g_queue_is_empty (&queue))
+                               g_object_unref (g_queue_pop_head (&queue));
+
+                       g_slist_free_full (stack, g_free);
+                       g_object_unref (part_list);
+                       g_free (end_partid);
+
+                       /* This part is neither signed, nor encrypted, but other parts
+                          are signed or encrypted, thus mark this one as with bad security. */
+                       if (any_secure)
+                               return "-e-mail-formatter-frame-security-bad";
+               }
+
                return "-e-mail-formatter-frame-security-none";
        } else {
                GList *head, *link;