--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extensions/rt_randomize/rt_randomize.c	Wed Aug 06 15:21:16 2014 +0200
@@ -0,0 +1,111 @@
+/*********************************************************************************************************
+* Software License Agreement (BSD License)                                                               *
+* Author: Thomas Klausner <tk@giga.or.at>                                                                *
+*                                                                                                        *
+* Copyright (c) 2014 Thomas Klausner                                                                     *
+* All rights reserved.                                                                                   *
+*                                                                                                        *
+* Written under contract by nfotex IT GmbH, http://nfotex.com/                                           *
+*                                                                                                        *
+* Redistribution and use of this software in source and binary forms, with or without modification, are  *
+* permitted provided that the following conditions are met:                                              *
+*                                                                                                        *
+* * Redistributions of source code must retain the above                                                 *
+*   copyright notice, this list of conditions and the                                                    *
+*   following disclaimer.                                                                                *
+*                                                                                                        *
+* * Redistributions in binary form must reproduce the above                                              *
+*   copyright notice, this list of conditions and the                                                    *
+*   following disclaimer in the documentation and/or other                                               *
+*   materials provided with the distribution.                                                            *
+*                                                                                                        *
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED *
+* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A *
+* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR *
+* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT     *
+* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS    *
+* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR *
+* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF   *
+* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.                                                             *
+*********************************************************************************************************/
+
+#include <freeDiameter/extension.h>
+
+/*
+ * Load balancing extension. If there are multiple highest-rated hosts with the same score,
+ * randomly increase the score of one of them.
+ */
+
+#include <stdlib.h>
+
+static int seed;
+
+static int rt_randomizing(void * cbdata, struct msg ** pmsg, struct fd_list * candidates)
+{
+	struct fd_list *lic;
+	struct msg * msg = *pmsg;
+	int max_score = -1;
+	int max_score_count = 0;
+	
+	TRACE_ENTRY("%p %p %p", cbdata, msg, candidates);
+	
+	CHECK_PARAMS(msg && candidates);
+	
+	/* Check if it is worth processing the message */
+	if (FD_IS_LIST_EMPTY(candidates))
+		return 0;
+
+	/* find out maximal score and how many candidates have it */
+	for (lic = candidates->next; lic != candidates; lic = lic->next) {
+		struct rtd_candidate * cand = (struct rtd_candidate *) lic;
+		if (max_score < cand->score) {
+			max_score = cand->score;
+			max_score_count = 1;
+		}
+		else if (cand->score == max_score) {
+			max_score_count++;
+		}
+	}
+
+	/* if there is more than one with positive score, randomly increase one of their scores by one */
+	if (max_score >= 0 && max_score_count > 1) {
+		int lucky_candidate = rand_r(&seed) % max_score_count;
+		int i = 0;
+
+		for (lic = candidates->next; lic != candidates; lic = lic->next) {
+			struct rtd_candidate * cand = (struct rtd_candidate *) lic;
+			if (cand->score == max_score) {
+				if (i == lucky_candidate) {
+					cand->score++;
+					break;
+				}
+				i++;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/* handler */
+static struct fd_rt_out_hdl * rt_randomizing_hdl = NULL;
+
+/* entry point */
+static int rt_randomize_entry(char * conffile)
+{
+	/* Register the callback */
+	CHECK_FCT(fd_rt_out_register(rt_randomizing, NULL, 4, &rt_randomizing_hdl));
+	seed = (int)time(NULL);
+	TRACE_DEBUG(INFO, "Extension 'Randomizing' initialized");
+	return 0;
+}
+
+/* Unload */
+void fd_ext_fini(void)
+{
+	/* Unregister the callbacks */
+	CHECK_FCT_DO(fd_rt_out_unregister(rt_randomizing_hdl, NULL), /* continue */);
+	return ;
+}
+
+EXTENSION_ENTRY("rt_randomize", rt_randomize_entry);