#!/bin/sh

# idlelatency.sh - Script to get latency statistics on an idle line
# This script starts a ping, then collects statistics on the latency
#   for a designated time period

# Usage: sh idlelatency.sh [-4 -6] [ -t duration ] [ -p host-to-ping ] 

# Options: If options are present:
#
# -4 | -6:       enable ipv4 or ipv6 testing (ipv4 is the default)
# -t | --time:   Duration for how long each direction's test should run - (default - 60 seconds)
# -p | --ping:   Host to ping to measure latency (default - gstatic.com)

# Copyright (c) 2014-2020 - Rich Brown rich.brown@blueberryhillsoftware.com
# GPLv2

# Summarize the contents of the ping's output file to show min, avg, median, max, etc.
#   input parameter ($1) file contains the output of the ping command

summarize_pings() {     
  
  # Process the ping times, and summarize the results
  # grep to keep lines that have "time=", then sed to isolate the time stamps, and sort them
  # awk builds an array of those values, and prints first & last (which are min, max) 
  # and computes average.
  # If the number of samples is >= 10, also computes median, and 10th and 90th percentile readings

  # stop pinging and drawing dots
  kill_pings
  kill_dots

  sed 's/^.*time=\([^ ]*\) ms/\1/' < $1 | grep -v "PING" | sort -n | \
  awk 'BEGIN {numdrops=0; numrows=0;} \
    { \
      if ( $0 ~ /timeout/ ) { \
          numdrops += 1; \
      } else { \
        numrows += 1; \
        arr[numrows]=$1; sum+=$1; \
      } \
    } \
    END { \
      pc10="-"; pc90="-"; med="-"; \
      if (numrows == 0) {numrows=1} \
      if (numrows>=10) \
      {   ix=int(numrows/10); pc10=arr[ix]; ix=int(numrows*9/10);pc90=arr[ix]; \
        if (numrows%2==1) med=arr[(numrows+1)/2]; else med=(arr[numrows/2]); \
      }; \
      pktloss = numdrops/(numdrops+numrows) * 100; \
      printf("\n  Latency: (in msec, %d pings, %4.2f%% packet loss)\n      Min: %4.3f \n    10pct: %4.3f \n   Median: %4.3f \n      Avg: %4.3f \n    90pct: %4.3f \n      Max: %4.3f\n", numrows, pktloss, arr[1], pc10, med, sum/numrows, pc90, arr[numrows] )\
     }'

  # and finally remove the PINGFILE
  rm $1

}

# Print a line of dots as a progress indicator.

print_dots() {
  while : ; do
    printf "."
    sleep 1s
  done
}

# Stop the current print_dots() process

kill_dots() {
  # echo "Pings: $ping_pid Dots: $dots_pid"
  kill -9 $dots_pid
  wait $dots_pid 2>/dev/null
  dots_pid=0
}

# Stop the current ping process

kill_pings() {
  # echo "Pings: $ping_pid Dots: $dots_pid"
  kill -9 $ping_pid 
  wait $ping_pid 2>/dev/null
  ping_pid=0
}

# Stop the current pings and dots, and exit
# ping command catches (and handles) first Ctrl-C, so you have to hit it again...
kill_pings_and_dots_and_exit() {
  kill_dots
  kill_pings
  echo "\nStopped"
  exit 1
}

# ------------ start_pings() ----------------
# Start printing dots, then start a ping process, saving the results to a PINGFILE

start_pings() {

  # Create temp file
  PINGFILE=`mktemp /tmp/measurepings.XXXXXX` || exit 1

  # Start dots
  print_dots &
  dots_pid=$!
  # echo "Dots PID: $dots_pid"

  # Start Ping
  if [ $TESTPROTO -eq "-4" ]
  then
    "${PING4}" $PINGHOST > $PINGFILE &
  else
    "${PING6}" $PINGHOST > $PINGFILE &
  fi
  ping_pid=$!
  # echo "Ping PID: $ping_pid"

}

# ------- Start of the main routine --------

# Usage: sh idlelatency.sh [ -4 -6 ] [ -t duration ] [ -p host-to-ping ]

# -4 or -6 to control whether to use IPv4 or IPv6
# “t” and “time” Time to run the test in each direction (default: 60 seconds)
# “p” and “ping” Host to ping for latency measurements (default: gstatic.com)

# set an initial values for defaults
TESTDUR="60"

PING4=ping
command -v ping4 > /dev/null 2>&1 && PING4=ping4
PING6=ping6

PINGHOST="gstatic.com"
TESTPROTO="-4"

# read the options

# extract options and their arguments into variables.
while [ $# -gt 0 ] 
do
    case "$1" in
      -4|-6) TESTPROTO=$1 ; shift 1 ;;
      -t|--time) 
        case "$2" in
          "") echo "Missing duration" ; exit 1 ;;
              *) TESTDUR=$2 ; shift 2 ;;
          esac ;;
      -p|--ping)
          case "$2" in
              "") echo "Missing ping host" ; exit 1 ;;
              *) PINGHOST=$2 ; shift 2 ;;
          esac ;;
      --) shift ; break ;;
        *) echo "Usage: sh idlelatency.sh [-4 -6] [ -t duration ] [ -p host-to-ping ]" ; exit 1 ;;
    esac
done

# Start the main test

if [ $TESTPROTO -eq "-4" ]
then
  PROTO="ipv4"
else
  PROTO="ipv6"
fi
DATE=`date "+%Y-%m-%d %H:%M:%S"`

# Catch a Ctl-C and stop the pinging and the print_dots
trap kill_pings_and_dots_and_exit HUP INT TERM

echo "$DATE Testing idle line while pinging $PINGHOST ($TESTDUR seconds)"
start_pings
sleep $TESTDUR
summarize_pings $PINGFILE