Initial commit
Change-Id: I6a4444e3c193dae437cd7929f4c39aba7b749efa
diff --git a/extensions/rt_randomize/rt_randomize.c b/extensions/rt_randomize/rt_randomize.c
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+/*********************************************************************************************************
+* 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 unsigned 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 = (unsigned 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);