#!/bin/bash

# sweetnsourbkr's wifi script for Atheros ver. 0.1
# This script enables wifi for my laptop outside the home network
# Run this script as root only

# Error codes:
# 0:   network has been acquired
# 100: must run script as root
# 101: network connection failed
# 102: user chose not to connect
# 103: syntax error

# Check to see if the user is root
if [[ "$(id -u)" != "0" ]]
then
  echo "You must run this as root!" ;
  exit 100 ;
fi

# In case there's no essid or key, asume it's a public network
if [[ $2 == "" ]]  
then 
  essid=any ;
else 
  essid=$2 ;		# Assign specified essid
fi
  
if [[ $3 == "" ]]  
then 
  key=off ;
else 
  key=$3 ;			# Assign specified WEP key
fi

# This function brings the interface online
if_up() {
  # Bring the interface up
  ifconfig $device up
  
  # Notify the user what network he/she is using
  if [[ $essid == "any" ]]
  then
    echo "Scanning for networks ..." ;
    iwlist $device scan |more ;			# List available networks
  else
    echo "Using essid $essid" ;
  fi
  
  # Notify the user what key he/she is using
  if [[ $key != "off" ]]
  then
    echo "Using new key $key" ;
  fi
	
  # Ask to connect
  echo "Attempt connection (y/n)?"
  read response

  # If chosen to connect, go to the next function
  # If chosen to choose a specific essid, exit the script and use
  # the additional arguments
  case $response in 
    'y')  dhcp_get
          ;;
    'Y')  dhcp_get
          ;;
    *)    if_down
          ;;
  esac
}

# Function to configure ath0 and obtain a DHCP IP address
dhcp_get() {
  echo "Configuring interface ...";
  iwconfig $device essid $essid key $key ;
  echo "Acquiring IP Address ... "; 
  dhcpcd -d -t 10 $device;
  # The following will check if there was an IP addr issued
  if [[ -f /etc/dhcpc/dhcpcd-ath0.pid ]]
  then
    echo "Connection ready!";
    echo ;
    iwconfig $device ;
    ifconfig $device ;
    exit 0 ;
  else
    echo "Connection attempt unsuccessful.";
    echo ;
    iwconfig $device ;    # dhcpcd will automatically bring ath0 down
    exit 101 ;
  fi
}

# If chosen not to connect, turn off the interface
if_down() {
  ifconfig $device down ;
  echo "WiFi interface not configured." ;
  exit 102 ;
}

# Initial greeting
case $1 in
  'ath0')  device="$1"
           if_up
           ;;
   *)	   echo "Usage $0 ath0 [essid] [key]"
           exit 103
           ;;
esac