#!/bin/bash
# Script to turn on sFlow(R) sampling using the sFlow version 5 MIB, see:
# http://www.sflow.org/
#
# Copyright (c) 2001 InMon Corp. Licensed under the terms of the InMon sFlow licence:
# http://www.inmon.com/technology/sflowlicense.txt

MINPARAMS=3
if [ $# -lt "$MINPARAMS" ] 
then
  echo "Usage: $0 switch community receiver [port] [rate] [interval] [timeout] [force]"
  echo "  where:"
  echo "    switch, IP address of sFlow enabled switch/router"
  echo "    community, SNMP community string"
  echo "    receiver, destination IP address for sFlow datagrams"
  echo "    port, destination UDP port for sFlow datagrams (default=6343)"
  echo "    rate, packet sampling rate (default=512)"
  echo "    interval, counter polling interval (default=60)"
  echo "    timeout, number of seconds to maintain sampling (default=3600)"
  echo "    force, 0 = respect existing reservations, 1 = force settings"
  echo "Note: Setting timeout to 0 stops sampling and frees resources"
  exit 1
fi

# initialize mandatory variables
SWITCH=$1
COMMUNITY=$2
RECEIVER=$3

# initialize optional variables
PORT=${4:-6343}
RATE=${5:-512}
INTERVAL=${6:-60}
TIMEOUT=${7:-3600}
USEFORCE=${8:-0}

# initialize static variables
OWNER="$HOSTNAME;$0" 
ADDRESSTYPE=1 # IP v4
SFLOWMIB=".1.3.6.1.4.1.14706.1"
IFINDEX="11.1.3.6.1.2.1.2.2.1.1"
 
echo "Finding a free slot in in the sFlowRcvrTable"

RCVRINDEX=$(snmpwalk -v 2c -Oqn -c $COMMUNITY $SWITCH $SFLOWMIB.1.4.1.2 | awk -v me=$OWNER -v useforce=$USEFORCE --source '
 BEGIN{lastFree=0; lastMine=0; last=0;}
 {
   split($1,parts,".");
   idx = parts[14];
   owner = $2;
   gsub("\"","",owner);  # remove quotes
   last = idx;
   if(owner == me) lastOwner = idx;
   if(owner == "") lastFree = idx;
 } 
 END{
   if(lastOwner) print lastOwner;
   else if(lastFree) print lastFree;
   else if(useforce) print last;
 }')

if [ ! $RCVRINDEX ]
then 
  echo "No free sFlowRcvrTable entries found, current sFlowRcvrOwners:"
  snmpwalk -v 2c -Oqn -c $COMMUNITY $SWITCH $SFLOWMIB.1.4.1.2 | awk --source '{print $2}'
  exit 1
fi 

if [ $TIMEOUT -eq 0 ]
then
  echo "Free sFlowRcvrTable entry $RCVRINDEX"
  snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.4.1.2.$RCVRINDEX s ""
  exit 1
fi

HEXRECEIVER=$(echo $RECEIVER | awk --source '{split($0,parts,"."); printf "%.2X%.2X%.2X%.2X",parts[1],parts[2],parts[3],parts[4]}')

echo "Grabbing entry in sFlowRcvrTable:"
echo "sFlowRcvrIndex       = $RCVRINDEX"
echo "sFlowRcvrOwner       = $OWNER"
echo "sFlowRcvrTimeout     = $TIMEOUT"
echo "sFlowRcvrAddressType = $ADDRESSTYPE"
echo "sFlowRcvrAddress     = $RECEIVER ($HEXRECEIVER)"
echo "sFlowRcvrPort        = $PORT"


snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.4.1.2.$RCVRINDEX s $OWNER $SFLOWMIB.1.4.1.3.$RCVRINDEX i $TIMEOUT $SFLOWMIB.1.4.1.5.$RCVRINDEX i $ADDRESSTYPE $SFLOWMIB.1.4.1.6.$RCVRINDEX x $HEXRECEIVER $SFLOWMIB.1.4.1.7.$RCVRINDEX i $PORT

if [ $? -ne 0 ]
then 
  echo "SNMP set failed"
  exit 1;
fi

echo "Grabbing entries in sFlowFsTable"

for ENTRY in $(snmpwalk -v 2c -Oqn -c $COMMUNITY $SWITCH $SFLOWMIB.1.5.1.3.$IFINDEX | awk -v myRcvrIndex=$RCVRINDEX -v useforce=$USEFORCE --source '
{
  split($1,parts,".");
  ifIndex = parts[25];
  instance = parts[26];

  reciever = $2;

  last[ifIndex] = instance;
  if(receiver == myRcvrIndex) lastOwner[ifIndex] = instance;
  if(receiver == 0) lastFree[ifIndex] = instance;
} 
END{
   for (i in last) {
     if(lastOwner[i]) print i "." lastOwner[i];
     else if(lastFree[i]) print i "." lastFree[i];
     else if(useforce) print i "." last[i];
   }
}'); do
  echo "sFlowFsDataSource.sFlowFsInstance=$ENTRY sFlowFsPacketSamplingRate=$RATE"

  if [ "$USEFORCE" -ne "0" ]
  then
    echo "Using force, clear entry first"
    snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.5.1.3.$IFINDEX.$ENTRY i 0
    echo "Now set values"
  fi
  snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.5.1.3.$IFINDEX.$ENTRY i $RCVRINDEX $SFLOWMIB.1.5.1.4.$IFINDEX.$ENTRY i $RATE
done

echo "Grabbing entries in sFlowCpTable"

for ENTRY in $(snmpwalk -v 2c -Oqn -c $COMMUNITY $SWITCH $SFLOWMIB.1.6.1.3.$IFINDEX | awk -v myRcvrIndex=$RCVRINDEX -v useforce=$USEFORCE --source '
{
  split($1,parts,".");
  ifIndex = parts[25];
  instance = parts[26];

  reciever = $2;

  last[ifIndex] = instance;
  if(receiver == myRcvrIndex) lastOwner[ifIndex] = instance;
  if(receiver == 0) lastFree[ifIndex] = instance;
} 
END{
   for (i in last) {
     if(lastOwner[i]) print i "." lastOwner[i];
     else if(lastFree[i]) print i "." lastFree[i];
     else if(useforce) print i "." last[i];
   }
}'); do

  echo "sFlowCpDataSource.sFlowCpInstance=$ENTRY sFlowCpInterval=$INTERVAL"

  if [ "$USEFORCE" -ne "0" ]
  then
    echo "Using force, clear entry first"
    snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.6.1.3.$IFINDEX.$ENTRY i 0
    echo "Now set values"
  fi
  
  snmpset -v 2c -c $COMMUNITY $SWITCH $SFLOWMIB.1.6.1.3.$IFINDEX.$ENTRY i $RCVRINDEX $SFLOWMIB.1.6.1.4.$IFINDEX.$ENTRY i $INTERVAL
done