connect.sh

#!/bin/bash

# 23/10/2013
# This script attempts to semi-automate / automate the wifi connection
# process from the command line.
# It is intended to be used on a headless machine without the
# requirement of typing several commands for a connection.
# The script stores previous connection credentials in PLAINTEXT as
# *.wpa files in the executed directory and in /etc/wpasupplicant.conf.
# These .wpa files are used to connect to several different AP using
# previously stored info.
# Probably a good idea to stop and other network managing software while
# running this script, also in testing wpa_supplicant does a pretty good
# job of re-connecting a disassociated link automatically.
#
# Mainly created from a combination of scripts taken from theses two
# sources:
# http://www.backtrack-linux.org/forums/archive/index.php/t-3367.html
# AND
# http://www.linuxquestions.org/questions/linux-general-1/wifi-connect\
# -script-tested-in-ubuntu-772646/
#
# old version 1  http://pastebin.com/Pa90HBiU  01/06/2013
#   very simple first version
# old version 2  http://pastebin.com/FzJnv5Nk  02/06/2013
#   minor additions
# old version 3  http://pastebin.com/3mu1XT5Y  08/06/2013
#   included ability to call up previous saved files from
#   command line.  Some checking of command line parameters and
#   checking for empty saved files
# old version 4
#   Added exit return values
# Current version 5
#   Removal of cleanslate function.  Capitalising of function names.
#   Renaming of some function names.
#   Addition of random_config to randomly select a previously saved
#   config files, check for internet access and keep trying another
#   connections if internet access is not made.  Can be used in
#   conjunction with -f to initially select a conf_file of your choice.
#   Improved program feedback and internet access checking.
#
# This script uses the following commands: find, printf, iwlist, awk,
# cat, kill, ps, grep, xargs, iwconfig, dhclient, wpa_supplicant, curl.
#
# Copy, Distribute and Modify Freely.
#


########################################################################
######################## FUNCTIONS #####################################

function HELP (){
    HELP_MESSAGE="$1"
    if [ "$HELP_MESSAGE" ]; then
        printf "$HELP_MESSAGE"
    fi
    printf "Usage: $0 -i [INTERFACE] OR AND -f [CONF_FILE.wpa] -r (RANDOM_CONF_MODE)\n"
}


function CHECK_ARGS () {
    #
    # Define Globals
    #
    INET_AVAIL=0
    RANDOM_CONF_MODE=0
    RANDOM_FIRST_RUN=0
    CONF_FILE=""
    INT=""

    if [ -z "$1" ]; then
    HELP
    exit 1
    fi

    while getopts  "i:f:r" opt
        do
            case $opt in
                i ) INT=${OPTARG};;
                f ) CONF_FILE=${OPTARG};;
                r ) RANDOM_CONF_MODE=1;;
                \?) HELP
                    exit 1;;
                * ) HELP
                    exit 1;;
            esac
        done

    #
    # check if root
    #
    if [ "$(id -u)" != "0" ]; then
        HELP "This script must be run as root\n"
        exit 1
    fi

    #
    # check if interface is entered as command line argument
    #
    if [ -z "$INT" ]; then
        HELP
        exit 1
    fi

    #
    # Check if interface entered exists
    #
    if [ ! -e /sys/class/net/$INT ]; then
        HELP "Network Interface $INT does not exist\n"
        exit 1
    fi

    #
    # If random mode selected, check if wpa files are available
    #
    if [ $RANDOM_CONF_MODE -eq 1 ]; then
        local WPA_FILES=$(find . -type f -name "*.wpa" | wc -l)
        if [ "$WPA_FILES" -eq 0  ]; then
            HELP "No *.wpa files exist for RANDOM_CONF_MODE\n"
            exit 1
        fi
    fi
}


function PINGCHECK (){
    #
    # Check for an internet connection using curl to download from a FQDN. 5 Second timeout.
    # Ref: http://superuser.com/questions/545865/how-to-check-if-internet-connection-is-available-via-terminal/625888#625888
    #
    printf "Checking for internet access...\n"
    curl --interface $INT -o /dev/null -m 5 -s http://www.google.com
    if [[ $? == 0 ]]; then
        INET_AVAIL=1
    else
        #
        # Check again for internet access
        #
        printf "Rechecking for internet access...\n"
        curl --interface $INT -o /dev/null -m 5 -s http://www.google.com
        if [[ $? == 0 ]]; then
            INET_AVAIL=1
        else
            INET_AVAIL=0
        fi
    fi
}


function READ_SAVED (){
    #
    # Accepts a filename argument to read a saved file.  Also can search or use previous saved
    # wpa configuration files.  Will automatically bypass new config prompting if RANDOM_CONF_MODE
    # is being used.
    # Filename checking involves testing file is greater than zero length and exists
    # before writing the configuration to wpa_supplicant.conf
    #

    local CONF_FILE=$1

    if [ $RANDOM_CONF_MODE -eq 0 ]; then
        if [ -n "$CONF_FILE" ]; then
            if [ -s "$CONF_FILE" ]; then
                printf "File $CONF_FILE exists, proceeding to connect\n"
                WRITE_CONF "$CONF_FILE"
                exit 0
            else
                printf "File $CONF_FILE is invalid or does not exist\n"
                CONF_CREATE
                exit 0
            fi
        fi
    else
        if [ -n "$CONF_FILE" ]; then
            if [ -s "$CONF_FILE" ]; then
                WRITE_CONF "$CONF_FILE"
                exit 1
            else
                printf "File $CONF_FILE is invalid or does not exist\n"
                RANDOM_CONF
                exit 1
            fi
        else
            RANDOM_CONF
            exit 1
        fi
    fi

    #
    # Save and change IFS so spaces in file names are not interpreted as
    # separate lines in the array
    #
    OLDIFS=$IFS
    IFS=$'\n'

    #
    # Read all file names into an array
    # ref:http://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html
    #
    # " -printf '%f\n' " removes path info from outputs
    #
    # ref:http://serverfault.com/questions/354403/remove-path-from-find-command-output
    #
    SAVED_LIST=($(find . -type f -name "*.wpa" -printf '%f\n'))

    #
    # restore ifs
    #
    IFS=$OLDIFS

    #
    # Tests for number of saved wifi connections, if none exit
    #
    if [ -z "${SAVED_LIST[0]}" ]; then
        printf "There are no previous saved wifi connections\n"
        #
        # Create new connection
        #
        CONF_CREATE
        exit 0
    fi

    #
    #PS3 Sets the prompt for the select statement below
    #
    PS3="Choose a previously saved wifi connection or 's' to skip: "

    #
    #Select one of the previous saved configurations to connect with or quit
    #
    select CONF_FILE in "${SAVED_LIST[@]}"; do
        #
        # Quit if selected number does not exist
        #
        if [ -z "$CONF_FILE" ] ; then
                printf "Skipping\n\n"
                PS3=""
                CONF_CREATE
                exit 0
        fi
        #
        # Quick check if file is greater than zero length and exists
        #
        if [ -s "$CONF_FILE" ]; then
            printf "File $CONF_FILE exists, proceeding to connect\n"
            PS3=""
            WRITE_CONF "$CONF_FILE"
            exit 0
            else
            printf "File $CONF_FILE is invalid or does not exist, proceeding to create a new configuration\n"
            PS3=""
            CONF_CREATE
            exit 0
        fi
    done
}


function RANDOM_CONF (){
    #
    # This function randomly select a previously saved config files, check for internet access and keep trying another
    # connections if internet access is not made.  If and internet connection is not found, it tries another
    # connection.  Could be used as a faiover by specifying -f as your initial preferred network.
    #

    local CONF_FILE=$1

    #
    # Test to check if RANDOM_FIRST_RUN is 1.  If so then proceed to connect using the config file specified first.
    #
    if [ $RANDOM_FIRST_RUN -eq 1 ]; then
        RANDOM_FIRST_RUN=0
        READ_SAVED "$CONF_FILE"
    fi

    #
    # Test if INET_AVAIL is 1, initial value is 0 and if connection is good then it is 1.  Used to loop and recheck for
    # a internet connection.  If there is no connection then it go to the random config selection.
    #

    if [ $INET_AVAIL -eq 1 ]; then
        #
        # Sleep for a random period of 600 to 900 seconds
        #
        sleep $(((RANDOM % 300)+600))
        PINGCHECK
        RANDOM_CONF
    else
        OLDIFS=$IFS
        IFS=$'\n'
        CONF_FILE=($(find . -type f -name "*.wpa" -printf '%f\n'|sort -R |tail -1))
        IFS=$OLDIFS
        READ_SAVED "$CONF_FILE"
    fi
    exit 1
}


function CONF_CREATE (){
    #
    # This is a user entry prompt function, used to create new config files.
    #

    #
    # Scans for wifi connections & isolates wifi AP name
    #
    eval LIST=( $(iwlist $INT scan 2>/dev/null | awk -F":" '/ESSID/{print $2}') )

    #
    #PS3 Sets the prompt for the select statement below
    #
    PS3="Choose a new ESSID to create a connection or 'q' to quit: "

    #
    # Tests for number of wifi connections, exits if none
    #
        if [ -z "${LIST[0]}" ]; then
            printf "No available wifi connection using $INT\n"
            exit 1
        fi

    #
    # Select from a LIST of scanned connections
    #
    select CONF_FILE in "${LIST[@]}"; do

        #
        # Quit if selected number does not exist or alpha in entered
        #
        if [ -z "$CONF_FILE" ] ; then
                printf "Exiting\n"
                exit 0
        fi

        #
        # Get user input for passphrase no need to escape spaces
        #
        printf "Enter the passphrase for $CONF_FILE?\n"
        read "PASSPHRASE"

        #
        # Append the CONF_FILE variable (ESSID) to .wpa to make a filename
        # for saved configs
        #
        FILENAME=$CONF_FILE".wpa"

        #
        # Run wpa_passphrase to generate a file for wpa_supplicant to
        # use, store it locally and in etc/wpa_supplicant.conf
        #
        printf "Running wpa_passphrase\n"
        wpa_passphrase "$CONF_FILE" "$PASSPHRASE" > "$FILENAME" | xargs
        #
        # Jump to WRITE_CONF function, append configuration filename
        # to CONF_FILE variable
        #

        PS3=""
        WRITE_CONF "$FILENAME"
        exit 1
    done
}


function WRITE_CONF (){

    local CONF_FILE=$1
    #
    # Copy local wpa_supplicant file to etc/wpa_supplicant.conf
    #
    printf "Writing new configuration file using $CONF_FILE\n"
    cat "$CONF_FILE">/etc/wpa_supplicant.conf | xargs
    #
    # Jump to connect function, pass on the ESSID variable for connection
    #
    CONNECT "$CONF_FILE"
    exit 1
}


function CONNECT (){
    #
    # Capture first incoming argument as SSID
    #
    local ESSID=$1

    #
    # Kill previous instances of wpa_supplicant to stop other instances
    # wpa_supplicant fighting several different AP's
    # Kill based on
    # ref: http://thegeekstuff.com/2011/10/grep-or-and-not-operators
    # and
    # http://stackoverflow.com/questions/3510673/find-and-kill-a-\
    # process-in-one-line-using-bash-and-regex
    #
    # Release dhcp ip's and bring down the interface
    #
    kill $(ps aux | grep -E '[w]pa_supplicant.*\'$INT'' |  awk '{print $2}') 2>/dev/null | xargs
    dhclient $INT -r
    ifconfig $INT down

    #
    # Assign new credentials to config file
    #
    iwconfig $INT mode managed essid "$ESSID"
    printf "Configured interface $INT; Config file is $ESSID\n"
    ifconfig $INT up
    printf "Interface $INT is up\n"
    wpa_supplicant -B -Dwext -i$INT -c/etc/wpa_supplicant.conf 2>/dev/null | xargs
    printf "wpa_supplicant running, sleeping for 15...\n"

    #
    # Wait to connect before asking for a ip address
    #
    sleep 15
    printf "Running dhclient\n"
    dhclient $INT

    #
    # Print current ip for interface to screen
    #
    ifconfig $INT | grep inet

    #
    # Check if internet is available and print status to screen
    #
    sleep 5
    PINGCHECK
    if [ $INET_AVAIL -eq 1 ]; then
        printf "Internet is available on this connection\n"
    else
        printf "Internet is unavailable on this connection\n"
    fi

    if [ $RANDOM_CONF_MODE -eq 1 ]; then
    RANDOM_CONF
    fi

    exit 0
}

########################################################################
######################## START HERE ####################################

#
# Call check args function to check the command line argument supplied are valid.
#
CHECK_ARGS "$@"

#
# Check if RANDOM_CONF_MODE is selected and/or config file specified, routes to correct function set
# with file name arguments or no arguments depending on what is specified.
#
if [ $RANDOM_CONF_MODE -eq 1 ]; then
    if [ "$CONF_FILE" ]; then
        RANDOM_FIRST_RUN=1
        RANDOM_CONF "$CONF_FILE"
    else
    RANDOM_CONF
    fi
else
    if [ "$CONF_FILE" ]; then
        READ_SAVED "$CONF_FILE"
    else
        READ_SAVED
    fi
fi

exit 0