hostsctl

#!/bin/bash

end='\033[0m'
red='\033[0;31m'
green='\033[0;32m'
yellow='\033[0;33m'
blue='\033[0;34m'
white='\033[0;37m'

export hostf="/etc/hosts"

pre=$1

if [[ $UID -ne 0 ]] && ! [[ $pre =~ (-h|--help) ]]; then
	echo -e "${red}Cannot run without super user privileges!${end}" && exit
fi

if [[ ! -f $hostf ]] && [[ "$pre" != "--restore" ]]; then
	echo -e "${red}hosts file not found!${end}" && exit
fi

bak_file=$HOME/.hostsctlbak

if [[ "$pre" != "--restore" ]]; then
	cp -f $hostf $bak_file
fi

if [[ $# -eq 0 ]];then
	echo "no valid inputs"
	exit
fi

opt=$1
export ip="$2"
export host="$3"


valid_ip()
{
    local ip=$1
    local stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?
    fi
    return $stat
}


add_hostto_ip() {
	local ip=$1
	local host=$2
	if [[ $(grep -cw "$ip" $hostf) -eq 0 ]]; then
		echo "$ip $host" >> $hostf
		return 0
	else
		sed -i "s/$ip\b/$ip $host/" $hostf
		return 0
	fi
}

check_duplicate() {
	local host=$1
	dup_count=$(grep -cw "$host" $hostf)
	if [[ $dup_count -gt 0 ]]; then
		echo -e "${red} This hostname already exists in the hosts file! ${end}\n\n Use -fa option to add a host forcefully!"
		exit
	fi
}

remove_host() {
	local ip=$1
	line=$(grep -w "$ip" $hostf)
	cip=$(echo $line | awk '{print $1}')
	check=$(echo $line | sed -e "s/${ip}\b//" -e "s/$cip\s//g" | sed 's/\s//g')
	if [[ "${check:0:1}" == '#'  ]] || [[ -z "$check" ]]; then
		sed -i "/$ip\b/d" $hostf
		return 0
	else
		sed -i "s/${ip}\b\s*//1" $hostf
		return 1
	fi
}

remove_ip() {	
	local ip=$1
	sed -i "/$ip\b/d" $hostf
	return 0
}

force_addhost() {
	local ip=$1
	local host=$2
	remove_host "$host"
	add_hostto_ip "$ip" "$host"
}

wexit() {
	sleep 1;exit
}

check_record() {
	record=$1
	if [[ $(grep -cw "$record" $hostf) -eq 0 ]]; then
		echo -e "${yellow}No matching entries for $record!${end}"
		wexit
	fi
}


case "$opt" in
	"-a"|"--add"|"-fa"|"--force-add")
		if [[ -n "$ip" ]] && [[ -n "$host" ]]; then
			if valid_ip $ip; then
				if valid_ip "$host"; then
					echo -e "${red}Host cannot be an ip address!${end}"
					wexit
				fi
				if [[ "$opt" == "-fa" ]] || [[ "$opt" == "--force-add" ]]; then 
					force_addhost "$ip" "$host"
					echo -e "${green}Forcefully added host $host${end}"
					wexit
				fi
				check_duplicate "$host"
				add_hostto_ip "$ip" "$host"
				if [[ $? -eq 0 ]]; then 
					echo -e "${green}host $host added successfully!${end}";
				else
					echo -e "${red}Failed to add the host $host!${end}";
				fi 
			else
				echo -e "${red}not a valid ip (make sure ip is the first option value)${end}"
			fi
		else
			echo -e "${red}option values are incomplete${end}"
		fi
	;;
	
	"-rh"|"--remove-host")
		if [[ -z $ip ]]; then 
			echo -e "${red}Host cannot be empty!${end}"; 
			wexit
		fi
		if valid_ip "$ip"; then
			echo -e "${red}Host name cannot be an IP!${end}"; 
			wexit
		fi
		check_record "$ip"
		remove_host "$ip"
		echo -e "${green}host $ip was removed!${end}"
		wexit
	;;

	"-ri"|"--remove-ip")
	if [[ -z $ip ]]; then 
		echo -e "${red}IP cannot be empty!${end}"; wexit
	fi
	check_record "$ip"
	remove_ip "$ip"
	echo -e "${green}IP $ip was removed!${end}"
	wexit
	;;

	"--restore")
	if [[ -f $bak_file ]]; then
		cp -f $bak_file $hostf
		echo -e "${green}Restored hosts file successfully!${end}"
		wexit
	fi
	echo -e "${red}Backup file not found!${end}"
	;;

	"-h"|"--help")
echo -e "
${blue}=======================${green}[[ USAGE ]]${blue}=======================${white}

adding a host\t\t\t:	hostsctl -a <ip> <hostname>
\t\t\t\t\thostsctl --add <ip> <hostname>
-------\n
adding host (forced)\t\t:	hostsctl -fa <ip> <hostname>
\t\t\t\t\thostsctl --force-add <ip> <hostname>
-------\n
removing by host\t\t:	hostsctl -rh <hostname>
\t\t\t\t\thostsctl --remove-host <hostname>
-------\n
removing by ip\t\t\t:	hostsctl -ri <ip>
\t\t\t\t\thostsctl --remove-ip <ip>$
-------\n
restore last change\t\t:	hostsctl --restore${end}
"
	;;

	*)
		echo "no options received / invalid option"
esac