[Minor] Deal with DSN messages

rules/misc.lua

@@ -188,7 +188,7 @@ rspamd_config.BROKEN_CONTENT_TYPE = {
     return fun.any(function(p) return p:is_broken() end,
       task:get_parts())
   end,
-  score = 3.0,
+  score = 1.5,
   group = 'header',
   description = 'Message has part with broken content type'
 }

src/libmime/content_type.c

@@ -144,7 +144,14 @@ rspamd_content_type_parse (const gchar *in,
 				RSPAMD_FTOK_ASSIGN (&srch, "message");
 
 				if (rspamd_ftok_cmp (&res->type, &srch) == 0) {
-					res->flags |= RSPAMD_CONTENT_TYPE_MESSAGE;
+					RSPAMD_FTOK_ASSIGN (&srch, "delivery-status");
+
+					if (rspamd_ftok_cmp (&res->subtype, &srch) == 0) {
+						res->flags |= RSPAMD_CONTENT_TYPE_TEXT|RSPAMD_CONTENT_TYPE_DSN;
+					}
+					else {
+						res->flags |= RSPAMD_CONTENT_TYPE_MESSAGE;
+					}
 				}
 			}
 		}

src/libmime/content_type.h

@@ -26,6 +26,7 @@ enum rspamd_content_type_flags {
 	RSPAMD_CONTENT_TYPE_MULTIPART = 1 << 1,
 	RSPAMD_CONTENT_TYPE_TEXT = 1 << 2,
 	RSPAMD_CONTENT_TYPE_MESSAGE = 1 << 3,
+	RSPAMD_CONTENT_TYPE_DSN = 1 << 4,
 };
 
 #define IS_CT_MULTIPART(ct) ((ct)->flags & RSPAMD_CONTENT_TYPE_MULTIPART)