| Brian Waters | 13d9601 | 2017-12-08 16:53:31 -0600 | [diff] [blame] | 1 | /********************************************************************************************************* |
| 2 | * Software License Agreement (BSD License) * |
| 3 | * Author: Thomas Klausner <tk@giga.or.at> * |
| 4 | * * |
| 5 | * Copyright (c) 2014 Thomas Klausner * |
| 6 | * All rights reserved. * |
| 7 | * * |
| 8 | * Written under contract by nfotex IT GmbH, http://nfotex.com/ * |
| 9 | * * |
| 10 | * Redistribution and use of this software in source and binary forms, with or without modification, are * |
| 11 | * permitted provided that the following conditions are met: * |
| 12 | * * |
| 13 | * * Redistributions of source code must retain the above * |
| 14 | * copyright notice, this list of conditions and the * |
| 15 | * following disclaimer. * |
| 16 | * * |
| 17 | * * Redistributions in binary form must reproduce the above * |
| 18 | * copyright notice, this list of conditions and the * |
| 19 | * following disclaimer in the documentation and/or other * |
| 20 | * materials provided with the distribution. * |
| 21 | * * |
| 22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED * |
| 23 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A * |
| 24 | * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR * |
| 25 | * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * |
| 26 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * |
| 27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR * |
| 28 | * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * |
| 29 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * |
| 30 | *********************************************************************************************************/ |
| 31 | |
| 32 | #include <freeDiameter/extension.h> |
| 33 | |
| 34 | /* |
| 35 | * Load balancing extension. If there are multiple highest-rated hosts with the same score, |
| 36 | * randomly increase the score of one of them. |
| 37 | */ |
| 38 | |
| 39 | #include <stdlib.h> |
| 40 | |
| 41 | static unsigned int seed; |
| 42 | |
| 43 | static int rt_randomizing(void * cbdata, struct msg ** pmsg, struct fd_list * candidates) |
| 44 | { |
| 45 | struct fd_list *lic; |
| 46 | struct msg * msg = *pmsg; |
| 47 | int max_score = -1; |
| 48 | int max_score_count = 0; |
| 49 | |
| 50 | TRACE_ENTRY("%p %p %p", cbdata, msg, candidates); |
| 51 | |
| 52 | CHECK_PARAMS(msg && candidates); |
| 53 | |
| 54 | /* Check if it is worth processing the message */ |
| 55 | if (FD_IS_LIST_EMPTY(candidates)) |
| 56 | return 0; |
| 57 | |
| 58 | /* find out maximal score and how many candidates have it */ |
| 59 | for (lic = candidates->next; lic != candidates; lic = lic->next) { |
| 60 | struct rtd_candidate * cand = (struct rtd_candidate *) lic; |
| 61 | if (max_score < cand->score) { |
| 62 | max_score = cand->score; |
| 63 | max_score_count = 1; |
| 64 | } |
| 65 | else if (cand->score == max_score) { |
| 66 | max_score_count++; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | /* if there is more than one with positive score, randomly increase one of their scores by one */ |
| 71 | if (max_score >= 0 && max_score_count > 1) { |
| 72 | int lucky_candidate = rand_r(&seed) % max_score_count; |
| 73 | int i = 0; |
| 74 | |
| 75 | for (lic = candidates->next; lic != candidates; lic = lic->next) { |
| 76 | struct rtd_candidate * cand = (struct rtd_candidate *) lic; |
| 77 | if (cand->score == max_score) { |
| 78 | if (i == lucky_candidate) { |
| 79 | cand->score++; |
| 80 | break; |
| 81 | } |
| 82 | i++; |
| 83 | } |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | return 0; |
| 88 | } |
| 89 | |
| 90 | /* handler */ |
| 91 | static struct fd_rt_out_hdl * rt_randomizing_hdl = NULL; |
| 92 | |
| 93 | /* entry point */ |
| 94 | static int rt_randomize_entry(char * conffile) |
| 95 | { |
| 96 | /* Register the callback */ |
| 97 | CHECK_FCT(fd_rt_out_register(rt_randomizing, NULL, 4, &rt_randomizing_hdl)); |
| 98 | seed = (unsigned int)time(NULL); |
| 99 | TRACE_DEBUG(INFO, "Extension 'Randomizing' initialized"); |
| 100 | return 0; |
| 101 | } |
| 102 | |
| 103 | /* Unload */ |
| 104 | void fd_ext_fini(void) |
| 105 | { |
| 106 | /* Unregister the callbacks */ |
| 107 | CHECK_FCT_DO(fd_rt_out_unregister(rt_randomizing_hdl, NULL), /* continue */); |
| 108 | return ; |
| 109 | } |
| 110 | |
| 111 | EXTENSION_ENTRY("rt_randomize", rt_randomize_entry); |