more robust solution to type checking for section bodies

Author: grs

lib/message.js

@@ -81,6 +81,16 @@ Section.prototype.described = function (item) {
     return types.described(types.wrap_ulong(this.typecode), types.wrap(item || this.content));
 };
 
+Section.prototype.collect_sections = function (sections) {
+    if (this.multiple) {
+        for (var i = 0; i < this.content.length; i++) {
+            sections.push(this.described(this.content[i]));
+        }
+    } else {
+        sections.push(this.described());
+    }
+};
+
 define_composite_section({
     name:'header',
     code:0x70,
@@ -136,14 +146,8 @@ define_map_section({name:'footer', code:0x78});
 
 
 function wrap_body (sections, msg) {
-    if (msg.body && msg.body.constructor === Section) {
-        if (msg.body.multiple) {
-            msg.body.content.forEach(function (s) {
-                sections.push(msg.body.described(s));
-            });
-        } else {
-            sections.push(msg.body.described());
-        }
+    if (msg.body && msg.body.collect_sections) {
+        msg.body.collect_sections(sections);
     } else {
         sections.push(types.described(types.wrap_ulong(0x77), types.wrap(msg.body)));
     }