#!/bin/bash

### Curby's Connection Tracker
### by Michael Lee
### v1.00.00, 2007-12-23

###   License
#
#  Copyright (C) 2007  Michael Lee <kirbysdl@yahoo.com>
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#  
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
# 
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#

# This script tracks network connectivity via pings to PING_TARGET with a
# timeout of PING_TIMEOUT seconds.

PING_TIMEOUT=1
PING_TARGET="67.18.176.31"

# Failure tracking:
#   Upon a failed ping, the state becomes "warning" and the next WARNING_COUNT
#   pings are sent WARNING_PERIOD seconds apart.  If WARNING_THRESHOLD or more
#   pings fail, state becomes "down", and pings are sent DOWN_PERIOD apart.

WARNING_COUNT=10
WARNING_PERIOD=1
WARNING_THRESHOLD=3

DOWN_PERIOD=1

# Success tracking:
#   Upon returning from down or warning, state becomes "recover" and the next
#   RECOVER_COUNT pings are sent RECOVER_PERIOD seconds apart.  If no failures,
#   the state becomes "stabilize" and the next STABILIZE_COUNT pings are sent
#   STABILIZE_PERIOD seconds apart.  Finally, the state becomes "up" and pings
#   are sent UP_PERIOD seconds apart.

RECOVER_COUNT=10
RECOVER_PERIOD=1
STABILIZE_COUNT=6
STABILIZE_PERIOD=10
UP_PERIOD=60



# Setup up initial state
state="RECOVER"
laststate="DOWN"
echo `date +%s`" ("`date`") starting up in state $state, pinging $PING_TARGET"

# Run forever
while true; do
  if ping -c 1 -t $PING_TIMEOUT $PING_TARGET > /dev/null 2>&1 ; then
    # Pings work
    case "$state" in
      # Stay UP
      "UP"        ) sleep $UP_PERIOD ;;
      "WARNING"   ) echo -n "."
                    tempcount=$((tempcount+1))
                    if [[ "$tempcount" -ge "$WARNING_COUNT" ]]; then
                      if [[ "$laststate" == "DOWN" ]]; then
                        state="RECOVER"
                      else
                        state=$laststate
                      fi
                      echo "]"
                      echo `date +%s`" ("`date`") WARNING --> $state (after $failcount failures)"
                      sleep $UP_PERIOD
                    else
                      sleep $WARNING_PERIOD
                    fi
                    ;;
      "DOWN"      ) state="RECOVER"
                    tempcount=1
                    echo `date +%s`" ("`date`") DOWN --> RECOVER"
                    sleep $RECOVER_PERIOD
                    ;;
      "RECOVER"   ) tempcount=$((tempcount+1))
                    if [[ "$tempcount" -ge "$RECOVER_COUNT" ]]; then
                      state="STABILIZE"
                      tempcount=0
                      echo `date +%s`" ("`date`") RECOVER --> STABILIZE"
                      sleep $STABILIZE_PERIOD
                    else
                      sleep $RECOVER_PERIOD
                    fi
                    ;;
      "STABILIZE" ) tempcount=$((tempcount+1))
                    if [[ "$tempcount" -ge "$STABILIZE_COUNT" ]]; then
                      state="UP"
                      echo `date +%s`" ("`date`") STABILIZE --> UP"
                      sleep $UP_PERIOD
                    else
                      sleep $STABILIZE_PERIOD
                    fi
                    ;;
      *           ) echo "uh-oh - unknown case for good ping '$state'";exit ;;
    esac
  else
    # Pings fail
    case "$state" in
      "RECOVER"|"STABILIZE"|"UP" )
                    tempcount=1
                    failcount=1
                    echo -n `date +%s`" ("`date`") $state --> WARNING [X"
                    laststate=$state
                    state="WARNING"
                    sleep $WARNING_PERIOD
                    ;;
      "WARNING"   ) echo -n "X"
                    tempcount=$((tempcount+1))
                    failcount=$((failcount+1))
                    if [[ "$failcount" -ge "$WARNING_THRESHOLD" ]]; then
                      state="DOWN"
                      echo "]"
                      echo `date +%s`" ("`date`") WARNING --> DOWN ($WARNING_THRESHOLD failures after $tempcount packets)"
                      sleep $DOWN_PERIOD
                    else
                      sleep $WARNING_PERIOD
                    fi
                    ;;
      "DOWN"      ) sleep $DOWN_PERIOD ;;
      *           ) echo "uh-oh - unknown case for bad ping '$state'" ;;
    esac
  fi
done