#!/bin/bash
#
# 2003-10-18  salsi@icosaedro.it
#
# 2005-11-21
# - removed option -w

prompt="==> "
prog_name=$( basename "$0" )
prefs="$HOME/.$prog_name.prefs"

# imposta default:
interface=lo
show_net_name=no
show_host_name=no
show_port_name=no
more_protocol_info=no
snaplens=68
print_time=no
verbosity=0
show_hex=no
show_ascii_too=no
show_ascii_too=no
parse_packets=no
save_on_exit=yes


function add_slashes()
{
	echo "$1" | sed 's/\(["$\\]\)/\\\1/g'
}


function show_yesno()
{
	if [ ${!2} = yes ]; then
		echo -n "[x]"
	else
		echo -n "[ ]"
	fi
	echo " $1"
}


function toggle_yesno()
{
	if [ ${!1} = yes ]; then
		eval $1=no
	else
		eval $1=yes
	fi
}


function get_string()
{
	local new IFS_ori
	echo -n "[${!1}] $prompt"
	IFS_ori="$IFS"
	read -r new
	IFS="$IFS_ori"
	if [ -z "$new" ]; then
		return
	fi
	new=$( add_slashes "$new" )
	eval "$1=\"$new\""
}


function build_cmd()
{
	local cmd
	cmd="tcpdump -i $interface -s $snaplens -l"
	if [ $parse_packets = "yes" ]; then
		if [ $show_host_name = yes  ]; then
			#if [ $show_port_name = yes ]; then
			#else
			#fi
			[ $show_net_name = yes ] && cmd="$cmd -a"
		else
			cmd="$cmd -nn"
		fi
		[ $more_protocol_info = no ] && cmd="$cmd -q"
		[ $print_time = no ] && cmd="$cmd -t"
		case $verbosity in
		1) cmd="$cmd -v" ;;
		2) cmd="$cmd -vv" ;;
		3) cmd="$cmd -vvv" ;;
		esac
		if [ $show_hex = yes ]; then
			cmd="$cmd -x"
			[ $show_ascii_too = yes ] && cmd="$cmd -X"
		fi
	fi
	echo "$cmd"
}


function load_prefs()
{
	if [ -f "$prefs" ]; then
		echo "Reading preferences from $prefs..."
		source "$prefs"
	fi
}


function out()
{
	while [ $# -gt 0 ]; do
		value=$( add_slashes "${!1}" )
		echo "$1=\"$value\""
		shift
	done
}


function save_prefs()
{
	out interface show_net_name show_host_name show_port_name \
		more_protocol_info snaplens print_time verbosity show_hex \
		show_ascii_too save_on_exit \
	> $prefs
}


function execute()
{
	local cmd
	cmd=$( build_cmd )
	eval "$cmd"
}


function Usage()
{
	echo "$prog_name - menu interface to tcpdump"
	echo "Usage:  $prog_name [-h] [--help] [interface]"
	exit
}


load_prefs
if [ "$1" = "-h" -o "$1" = "--help" ]; then
	Usage
fi
[ $# -gt 0 ] && interface="$@"
while :; do
	echo
	echo "$prog_name - menu interface to tcpdump"
	echo "i Interface: $interface"
	echo "l No. of bytes to snarf ([68,65535]): $snaplens"
	echo "p $(show_yesno "Parse packets" parse_packets)"
	if [ $parse_packets = yes ]; then
		echo "t     $(show_yesno "Print a timestamp in each dump line" print_time)"
		echo "m     $(show_yesno "Print more protocol information on output" more_protocol_info)"
		echo "h     $(show_yesno "Convert host addresses to names" show_host_name)"
		if [ $show_host_name = yes ]; then
			echo "n         $(show_yesno "Attempt to convert network and broadcast addresses to names" show_net_name)"
			echo "c         $(show_yesno "Convert protocol and port numbers to names" show_port_name)"
		fi
		echo "v     Verbosity level ([0,3]): $verbosity"
		echo "H     $(show_yesno "Print each packet (minus its link level header) in hex" show_hex)"
		if [ $show_hex = yes ]; then
			echo "a         $(show_yesno "Print ascii too" show_ascii_too)"
		fi
	fi
		
	echo "S $(show_yesno "Save settings on exit to the file $prefs" save_on_exit)"
	echo "s Show resulting command"
	echo "x Execute"
	echo "q Quit"
	echo -n "$prompt"
	read -n 1 opt
	echo
	case "$opt" in
	i) get_string interface ;;
	p) toggle_yesno parse_packets ;;
	n) toggle_yesno show_net_name ;;
	h) toggle_yesno show_host_name ;;
	c) toggle_yesno show_port_name ;;
	m) toggle_yesno more_protocol_info ;;
	l) get_string snaplens ;;
	t) toggle_yesno print_time ;;
	v) get_string verbosity
		if [ "$verbosity" -lt 0 ]; then
			verbosity=0
		fi
		if [ "$verbosity" -gt 3 ]; then
			verbosity=3
		fi
		;;
	H) toggle_yesno show_hex ;;
	a) toggle_yesno show_ascii_too ;;
	S) toggle_yesno save_on_exit ;;
	s) echo -e "Resulting command:\n$(build_cmd)" ;;
	x) execute ;;
	q) [ $save_on_exit = yes ] && save_prefs; exit ;;
	esac
done