#!/bin/sh
#
# capture.sh, Copyright © 2011 Matteo Cypriani <mcy@lm7.fr>
#
########################################################################
# This program is licensed under the terms of the Expat license.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
########################################################################
#
# Captures a few packets on a Wi-Fi interface, using Tcpdump, and
# writes them to a Pcap file along with some information about the
# system. A tarball containing all these files is finally created.

#set -x
set -e

error()
{
	echo "$1"
	exit 1
}

[ $# -eq 1 ] \
	|| error "Usage: $0 <wifi_interface>"

which tcpdump >/dev/null \
	|| error "tcpdump is required to run this program!"

## Parameters (tune them if you want) ##
# Number of packet to capture:
NB_PKT=10
# Temporary directory:
TMP=/tmp
# Name of the capture file:
FILE=capture.pcap
# Channel to scan
CHANNEL=1

## Generated parameters ##
# Interface to capture from:
IFACE=$1
# Machine information:
OS=`uname`
OS_RELEASE=`uname -r`
HOSTNAME=`uname -n`

echo -n "Shuting down interface $IFACE... "
ifconfig $IFACE down && echo "OK." \
	|| error "Cannot shut down the interface!"

echo -n "Switching interface $IFACE to monitor mode... "
case $OS in
	Linux)
		[ -x /sbin/iwconfig ] \
			|| error "iwconfig is required to run this program on Linux!"
		iwconfig $IFACE mode monitor channel $CHANNEL \
			&& echo "OK." \
			|| error "Cannot configure the interface!"
		;;
	*)
		error "Your OS is not supported."
		;;
esac

echo -n "Turning up interface $IFACE... "
ifconfig $IFACE up && echo "OK." \
	|| error "Cannot turn the interface up!"

echo "Capturing $NB_PKT packets..."
DIR=$(mktemp -d "$TMP"/capture_${OS}-${OS_RELEASE}_${IFACE}_${HOSTNAME}-XXXXXXXXXX)
FILE="$DIR/$FILE"
tcpdump -i $IFACE -c $NB_PKT -w "$FILE"
echo "Capture file \"$FILE\" created."

echo -n "Gathering system information... "
# Kernel & other information:
uname -a >"$DIR"/uname-a
# Wi-Fi interface information:
ifconfig $IFACE >"$DIR"/ifconfig_$IFACE
# PCI devices:
which lspci >/dev/null \
	&& lspci >"$DIR"/lspci \
	|| echo "lspci not available! Please install pciutils. "
# Loaded kernel modules & USB devices:
case $OS in
	Linux)
		lsmod >"$DIR"/lsmod
		which lsusb >/dev/null \
			&& lsusb >"$DIR"/lsusb \
			|| echo "lsusb not available! Please install usbutils. "
		;;
	DragonFly)
		kldstat >"$DIR"/kldstat
		which usbstats >/dev/null \
			&& usbstats >"$DIR"/usbstats \
			|| echo "usbstats not available! Please install usbutil. "
		;;
esac
echo "OK."

FILE="${DIR}.tar.gz"
DIR=`basename "$DIR"`
tar -C "$TMP" -czf "$FILE" "$DIR"
echo "Archive \"$FILE\" created."
rm -fr "$TMP/$DIR"

echo
echo "You can now shut down the interface $IFACE if you want:"
echo "	ifconfig $IFACE down"