Issue an VCL_error if 'esi' is not used from vcl_fetch.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2177 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache_vrt_esi.c

@@ -533,6 +533,13 @@ VRT_ESI(struct sess *sp)
 	int i;
 
 	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
+	if (sp->cur_method != VCL_MET_FETCH) {
+		/* XXX: we should catch this at compile time */
+		WSP(sp, SLT_VCL_error,
+		    "esi can only be called from vcl_fetch", "");
+		return;
+	}
+
 	CHECK_OBJ_NOTNULL(sp->obj, OBJECT_MAGIC);
 
 	/* XXX: only if GET ? */