[gmime] Modified GMimeParser to work around broken mailers that send encoded message/rfc822 parts

[Rico Tzschichholz <ricotz src gnome org>]

commit a7d6af5d69d0f5106fc8c0fe2a7218d294909870
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Sun Nov 25 10:27:56 2018 -0500

    Modified GMimeParser to work around broken mailers that send encoded message/rfc822 parts
    
    Fixes https://gitlab.gnome.org/GNOME/gmime/issues/1

 gmime/gmime-parser.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)
---
diff --git a/gmime/gmime-parser.c b/gmime/gmime-parser.c
index ef65d7d0..4261a4ac 100644
--- a/gmime/gmime-parser.c
+++ b/gmime/gmime-parser.c
@@ -1761,17 +1761,61 @@ parser_scan_message_part (GMimeParser *parser, GMimeParserOptions *options, GMim
        g_object_unref (message);
 }
 
+static gboolean
+is_rfc822 (const char *subtype)
+{
+       if (!g_ascii_strcasecmp (subtype, "rfc2822"))
+               return TRUE;
+       if (!g_ascii_strcasecmp (subtype, "rfc822"))
+               return TRUE;
+       if (!g_ascii_strcasecmp (subtype, "global"))
+               return TRUE;
+       if (!g_ascii_strcasecmp (subtype, "news"))
+               return TRUE;
+       return FALSE;
+}
+
 static GMimeObject *
 parser_construct_leaf_part (GMimeParser *parser, GMimeParserOptions *options, ContentType *content_type, 
gboolean toplevel, BoundaryType *found)
 {
        struct _GMimeParserPrivate *priv = parser->priv;
+       const char *subtype = content_type->subtype;
+       const char *type = content_type->type;
        GMimeObject *object;
        Header *header;
        guint i;
        
        g_assert (priv->state >= GMIME_PARSER_STATE_HEADERS_END);
        
-       object = g_mime_object_new_type (options, content_type->type, content_type->subtype);
+       if (!g_ascii_strcasecmp (type, "message") && is_rfc822 (subtype)) {
+               gboolean is_encoded = FALSE;
+               
+               for (i = 0; i < priv->headers->len; i++) {
+                       header = priv->headers->pdata[i];
+                       
+                       if (g_ascii_strcasecmp (header->name, "Content-Transfer-Encoding") != 0)
+                               continue;
+                       
+                       switch (g_mime_content_encoding_from_string (header->raw_value)) {
+                       case GMIME_CONTENT_ENCODING_QUOTEDPRINTABLE:
+                       case GMIME_CONTENT_ENCODING_UUENCODE:
+                       case GMIME_CONTENT_ENCODING_BASE64:
+                               is_encoded = TRUE;
+                               break;
+                       default:
+                               break;
+                       }
+                       
+                       break;
+               }
+               
+               if (is_encoded) {
+                       subtype = "octet-stream";
+                       type = "application";
+               }
+       }
+       
+       object = g_mime_object_new_type (options, type, subtype);
        
        if (!content_type->exists) {
                GMimeContentType *mime_type;