Dynamic shecan.ir configurator.

configure_dns.sh

#! /bin/bash

#####################################################
#      Fetch DNS configurations from shecan.ir      #
#####################################################

set -e

reset=`tput sgr0`
red=`tput setaf 1`
green=`tput setaf 2`
blue=`tput setaf 4`

# Prints out a success message.
function success { echo ${green}[+] ${1}${reset}; }

# Prints out a fail message.
function fail { echo ${red}[-] ${1}${reset}; }

# Prints out an info message.
function info { echo ${blue}[*] ${1}${reset}; }

# Default URL to get DNS configurations.
url='https://shecan.ir'

# Checks if a url is provided as the first input.
if [ ! -z $1 ]; then
    url=$1
fi

# Default class name of the element.
hook='shecan-dns-ips'

# Checks if a hook is provided as the second input.
if [ ! -z $2 ]; then
    hook=$2
fi

info "Fetching payload from '${url}'."

{
    payload=$(curl -sX GET ${url}) &&
    success "URL's payload has been cached."
} || {
    fail "Error on caching URL's payload!"
}

# The RegEx pattern to get the configurations within payload.
extractConfig="(?<=class=\"${hook}\">).*?(?=<\/span>)"

info "Extracting configurations from payload."

{
    configs=$(grep -Po ${extractConfig} <<< ${payload} 2> /dev/null) &&
    success "DNS configurations has been extracted from payload."
} || {
    fail "Error on extracting configurations from payload!"
}

# DNS's configuration key.
key="nameserver"

# path to DNS configurations.
filePath="/etc/resolv.conf"

# The RegEx pattern for IPv4.
ipv4RegEx=^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$

# Get line number of the first local DNS configuration.
first=$(grep -n ${key} ${filePath} | cut -f 1 -d ':' | head -n 1)

info "Editing '${filePath}'."

# Include fetched DNS configurations in DNS config file.
for config in $configs; do
    if [[ $config =~ $ipv4RegEx ]]; then
        sudo sed -i "${first}i\nameserver ${config}" $filePath
    fi
done

success "Enjoy your freedom :)"