#!/bin/bash
# Users 'tc' to emulate a link with a set data rate, delay and drop rate
# Run 'vn-link -h' to see the help

# Returns the current link rate
function get_current_rate {
	interface=$1

	linkclass=`tc class show dev $interface`;

	# Check that the class is set. 
	# If not, then set rate to -1 (meaning not set)
	if [ ! "$linkclass" ]; then
		echo "-1";
	else
		# Check there is a parameter
		paramexist=`echo $linkclass | grep "rate"`
	
		if [ "$paramexist" ]; then
			paramname=`echo $paramexist | cut -d " " -f 9`;
			paramvalue=`echo $paramexist | cut -d " " -f 10`;
			if [ "$paramname" = "rate" ]; then
				echo $paramvalue
			else
				echo "-1"
			fi
		else
			echo "-1"
		fi
	fi
}

# Returns the current link delay
function get_current_delay {
	interface=$1
	linkvalues=`tc qdisc show dev $interface | grep delay`;

	# Check that the class is set. 
	# If not, then set rate to -1 (meaning not set)
	if [ ! "$linkvalues" ]; then
		echo "-1";
	else
		paramname=`echo $linkvalues | cut -d " " -f 8`;
		paramvalue=`echo $linkvalues | cut -d " " -f 9`;
		if [ "$paramname" = "delay" ]; then
			echo $paramvalue
		else
			# Try again in different positions
			paramname=`echo $linkvalues | cut -d " " -f 10`;
			paramvalue=`echo $linkvalues | cut -d " " -f 11`;
			if [ "$paramname" = "delay" ]; then
				echo $paramvalue
			else
				echo "-1"
			fi
		fi
	fi
}

# Returns the current link jitter
function get_current_jitter {
	interface=$1

	echo "-1";
}

function print_help {
	echo "vn-link views and sets virtual link characteristics.";
	echo "vn-link applies on outgoing links only. It uses tc to";
	echo "set the link data rate, delay and jitter. For example,";
	echo "with the following network:";
	echo "    A (eth1) ------- 100Mb/s, 1ms ----- B (eth0) ";
	echo "there is a real 100Mb/s duplex link with 1ms delay";
	echo "between computers A and B. You can use virtnet to ";
	echo "modify the link characteristics:";
	echo " - limit the output data rate (to be less than actual)";
	echo " - add extra delay to all outgoing packets";
	echo " - add extra jitter to all outgoing packets";
	echo "For example, to create the following network:";
	echo "    A (eth1) -------  20Mb/s, 5ms ----- B (eth0) ";
	echo "on computer A run:";
	echo " vn-link --interface eth1 --set --rate 20mbit --delay 4.0ms";
	echo "Then the output rate for eth1 interface will be set to";
	echo "20 Mbit/s, and an additional 4ms delay added (since ";
	echo "real delay was 1ms, thats should give a total of 5ms).";
	echo "A similar command, using eth0, should be used on B";
	echo "for the link from B to A.";
}


# Get command line options
# From: http://mywiki.wooledge.org/BashFAQ/035#getopts

# Reset all variables that might be set
file=""
verbose=0

setvalues=0; # By default, get values
clearvalues=0; # By default, don't clear values

while :
do
	case $1 in
	-h | --help | -\?)
		#  Call your Help() or usage() function here.
		print_help
		exit 0      # This is not an error, User asked help. Don't do "exit 1"
		;;
	-c | --clear)
		# Clear values 
		clearvalues=1;
		shift
		;;
	-s | --set)
		# Set values
		setvalues=1;
		shift
		;;
	-g | --get)
		# Get values
		setvalues=0;
		shift
		;;
	-i | --interface)
		# Interface
		interface=$2
		shift 2
		;;
	--interface=*)
		interface=${1#*=}
		shift
		;;
	-r | --rate)
		# Link output rate
		rate=$2
		shift 2
		;;
	--rate=*)
		rate=${1#*=}
		shift
		;;
	-d | --delay)
		# Link delay
		delay=$2
		shift 2
		;;
	--delay=*)
		delay=${1#*=}
		shift
		;;
	-j | --jitter)
		# Link jitter
		jitter=$2
		shift 2
		;;
	--jitter=*)
		jitter=${1#*=}
		shift
		;;
        -f | --file)
            file=$2     # You might want to check if you really got FILE
            shift 2
            ;;
        --file=*)
            file=${1#*=}        # Delete everything up till "="
            shift
            ;;
        -v | --verbose)
            # Each instance of -v adds 1 to verbosity
            verbose=$((verbose+1))
            shift
            ;;
        --) # End of all options
            shift
            break
            ;;
        -*)
            echo "WARN: Unknown option (ignored): $1" >&2
            shift
            ;;
        *)  # no more options. Stop while loop
            break
            ;;
    esac
done

# Suppose some options are required. Check that we got them.

#if [ ! "$file" ]; then
#    echo "ERROR: option '--file FILE' not given. See --help" >&2
#    exit 1
#fi
# Rest of the program here.
# If there are input files (for example) that follow the options, they
# will remain in the "$@" positional parameters.
 
# Every operation must be on an interface, i.e. the -i option is required
if [ ! "$interface" ]; then
	echo "ERROR: option '--interface INTERFACE' not given. See --help" >&2
	exit 1
fi


# Set parameters to given values
if [ "$setvalues" = "1" ]; then
	# First retrieve the current values. We will only change the 
	# values that are given on the command line. Other values will
	# be kept the same as before (unless a reset is requested)

	currentrate=`get_current_rate $interface`
	currentdelay=`get_current_delay $interface`
	currentjitter=`get_current_jitter $interface`

	# If the value is not given on command line, then check if
	# there is a current value. If so, then use it.
	if [ ! "$rate" ]; then
		if [ "$currentrate" != "-1" ]; then
			rate=$currentrate;
		fi
	fi
	if [ ! "$delay" ]; then
		if [ "$currentdelay" != "-1" ]; then
			delay=$currentdelay;
		fi
	fi
	if [ ! "$jitter" ]; then
		if [ "$currentjitter" != "-1" ]; then
			delay=$currentjitter;
		fi
	fi

	# Display the current values
	echo "Old values"
	if [ "$currentrate" != "-1" ]; then
		echo "  Rate: $currentrate"
	else
		echo "  Rate: not set"
	fi
	if [ "$currentdelay" != "-1" ]; then
		echo "  Delay: $currentdelay"
	else
		echo "  Delay: not set"
	fi
	if [ "$currentjitter" != "-1" ]; then
		echo "  Jitter: $currentjitter"
	else
		echo "  Jitter: not set"
	fi

	# If the value exists, then set it.
	# First delete the current tc qdisc
	tc qdisc del dev $interface root

	# Now add the parent	
	tc qdisc add dev $interface root handle 1:0 htb default 10

	echo "New values"
	# Set the rate if it exists
	if [ "$rate" ]; then
		tc class add dev $interface parent 1:0 classid 1:10 htb rate $rate
		echo "  Rate: $rate"
	else
#		tc class add dev $interface parent 1:0 classid 1:10 htb
		echo "  Rate: not set"
	fi
	if [ "$delay" ]; then
		if [ "$jitter" ]; then
			tc qdisc change dev $interface parent 1:10 handle 10:0 netem delay $delay $jitter
			echo "  Delay: $delay"
			echo "  Jitter: $jitter"
		else
			tc qdisc add dev $interface parent 1:10 handle 10:0 netem delay $delay
			echo "  Delay: $delay"
			echo "  Jitter: not set"
		fi
	else
		echo "  Delay: not set"
		echo "  Jitter: not set"
	fi
else
	# Clear the values
	if [ "$clearvalues" = "1" ]; then
		tc qdisc del dev $interface root
	fi

	# Get values

	currentrate=`get_current_rate $interface`
	currentdelay=`get_current_delay $interface`
	currentjitter=`get_current_jitter $interface`
	echo "Current values"
	if [ "$currentrate" != "-1" ]; then
		echo "  Rate: $currentrate"
	else
		echo "  Rate: not set"
	fi
	if [ "$currentdelay" != "-1" ]; then
		echo "  Delay: $currentdelay"
	else
		echo "  Delay: not set"
	fi
	if [ "$currentjitter" != "-1" ]; then
		echo "  Jitter: $currentjitter"
	else
		echo "  Jitter: not set"
	fi


fi