lib/sflow_poller.c

   1 /* Copyright (c) 2002-2009 InMon Corp. Licensed under the terms of either the
   2  *   Sun Industry Standards Source License 1.1, that is available at:
   3  *    http://host-sflow.sourceforge.net/sissl.html
   4  * or the InMon sFlow License, that is available at:
   5  *    http://www.inmon.com/technology/sflowlicense.txt
   6  */
   7
   8 #include "sflow_api.h"
   9
  10 /*_________________--------------------------__________________
  11   _________________    sfl_poller_init       __________________
  12   -----------------__________________________------------------
  13 */
  14
  15 void sfl_poller_init(SFLPoller *poller,
  16                      SFLAgent *agent,
  17                      SFLDataSource_instance *pdsi,
  18                      void *magic,         /* ptr to pass back in getCountersFn() */
  19                      getCountersFn_t getCountersFn)
  20 {
  21     /* copy the dsi in case it points to poller->dsi, which we are about to clear */
  22     SFLDataSource_instance dsi = *pdsi;
  23
  24     /* preserve the *nxt pointer too, in case we are resetting this poller and it is
  25        already part of the agent's linked list (thanks to Matt Woodly for pointing this out) */
  26     SFLPoller *nxtPtr = poller->nxt;
  27
  28     /* clear everything */
  29     memset(poller, 0, sizeof(*poller));
  30
  31     /* restore the linked list ptr */
  32     poller->nxt = nxtPtr;
  33
  34     /* now copy in the parameters */
  35     poller->agent = agent;
  36     poller->dsi = dsi; /* structure copy */
  37     poller->magic = magic;
  38     poller->getCountersFn = getCountersFn;
  39 }
  40
  41 /*_________________--------------------------__________________
  42   _________________       reset              __________________
  43   -----------------__________________________------------------
  44 */
  45
  46 static void reset(SFLPoller *poller)
  47 {
  48     SFLDataSource_instance dsi = poller->dsi;
  49     sfl_poller_init(poller, poller->agent, &dsi, poller->magic, poller->getCountersFn);
  50 }
  51
  52 /*_________________---------------------------__________________
  53   _________________      MIB access           __________________
  54   -----------------___________________________------------------
  55 */
  56 u_int32_t sfl_poller_get_sFlowCpReceiver(SFLPoller *poller) {
  57     return poller->sFlowCpReceiver;
  58 }
  59
  60 void sfl_poller_set_sFlowCpReceiver(SFLPoller *poller, u_int32_t sFlowCpReceiver) {
  61     poller->sFlowCpReceiver = sFlowCpReceiver;
  62     if(sFlowCpReceiver == 0) reset(poller);
  63     else {
  64         /* retrieve and cache a direct pointer to my receiver */
  65         poller->myReceiver = sfl_agent_getReceiver(poller->agent, poller->sFlowCpReceiver);
  66     }
  67 }
  68
  69 u_int32_t sfl_poller_get_sFlowCpInterval(SFLPoller *poller) {
  70     return poller->sFlowCpInterval;
  71 }
  72
  73 void sfl_poller_set_sFlowCpInterval(SFLPoller *poller, u_int32_t sFlowCpInterval) {
  74     poller->sFlowCpInterval = sFlowCpInterval;
  75     if(sFlowCpInterval) {
  76         /* Set the countersCountdown to be a randomly selected value between 1 and
  77            sFlowCpInterval. That way the counter polling will be desynchronised
  78            (on a 200-port switch, polling all the counters in one second could be harmful).
  79            In a large network, even this might not be ideal if time-synchroniziation
  80            between devices is close and counters are always polled on second boundaries. If
  81            1000 different devices all send an sFlow datagram on the same second boundary
  82            it could result in an antisocial burst.
  83            However when counter-samples are packed into the export datagram they do not
  84            always result in that datagram being sent immediately. It is more likely that
  85            a subsequent packet-sample will be the one that triggers the datagram to be sent.
  86            The packet-sample events are not sychronized to any clock, so that results in
  87            excellent desynchronization (http://blog.sflow.com/2009/05/measurement-traffic.html).
  88            Another smoothing factor is that the tick() function called here is usually
  89            driven from a fairly "soft" polling loop rather than a hard real-time event.
  90         */
  91         poller->countersCountdown = 1 + (random() % sFlowCpInterval);
  92     }
  93     else {
  94         /* Setting sFlowCpInterval to 0 disables counter polling altogether.  Thanks to
  95            Andy Kitchingman for spotting this ommission. */
  96         poller->countersCountdown = 0;
  97     }
  98 }
  99
 100 /*_________________---------------------------------__________________
 101   _________________          bridge port            __________________
 102   -----------------_________________________________------------------
 103   May need a separate number to reference the local bridge port
 104   to get counters if it is not the same as the global ifIndex.
 105 */
 106
 107 void sfl_poller_set_bridgePort(SFLPoller *poller, u_int32_t port_no) {
 108     poller->bridgePort = port_no;
 109 }
 110
 111 u_int32_t sfl_poller_get_bridgePort(SFLPoller *poller) {
 112     return poller->bridgePort;
 113 }
 114
 115 /*_________________---------------------------------__________________
 116   _________________   sequence number reset         __________________
 117   -----------------_________________________________------------------
 118   Used to indicate a counter discontinuity
 119   so that the sflow collector will know to ignore the next delta.
 120 */
 121 void sfl_poller_resetCountersSeqNo(SFLPoller *poller) {  poller->countersSampleSeqNo = 0; }
 122
 123 /*_________________---------------------------__________________
 124   _________________    sfl_poller_tick        __________________
 125   -----------------___________________________------------------
 126 */
 127
 128 void sfl_poller_tick(SFLPoller *poller, time_t now)
 129 {
 130     if(poller->countersCountdown == 0) return; /* counters retrieval was not enabled */
 131     if(poller->sFlowCpReceiver == 0) return;
 132
 133     if(--poller->countersCountdown == 0) {
 134         if(poller->getCountersFn != NULL) {
 135             /* call out for counters */
 136             SFL_COUNTERS_SAMPLE_TYPE cs;
 137             memset(&cs, 0, sizeof(cs));
 138             poller->getCountersFn(poller->magic, poller, &cs);
 139             /* this countersFn is expected to fill in some counter block elements
 140                and then call sfl_poller_writeCountersSample(poller, &cs); */
 141         }
 142         /* reset the countdown */
 143         poller->countersCountdown = poller->sFlowCpInterval;
 144     }
 145 }
 146
 147 /*_________________---------------------------------__________________
 148   _________________ sfl_poller_writeCountersSample  __________________
 149   -----------------_________________________________------------------
 150 */
 151
 152 void sfl_poller_writeCountersSample(SFLPoller *poller, SFL_COUNTERS_SAMPLE_TYPE *cs)
 153 {
 154     /* fill in the rest of the header fields, and send to the receiver */
 155     cs->sequence_number = ++poller->countersSampleSeqNo;
 156 #ifdef SFL_USE_32BIT_INDEX
 157     cs->ds_class = SFL_DS_CLASS(poller->dsi);
 158     cs->ds_index = SFL_DS_INDEX(poller->dsi);
 159 #else
 160     cs->source_id = SFL_DS_DATASOURCE(poller->dsi);
 161 #endif
 162     /* sent to my receiver */
 163     if(poller->myReceiver) sfl_receiver_writeCountersSample(poller->myReceiver, cs);
 164 }
 165