shecanman

#!/bin/bash

# Author: Amir Rezazadeh (@amirz98)
# Project: ShecanMan (https://github.com/amirz98/shecanman)
#
# If you have found any issue or have some feature request:
# Please raise them here: https://github.com/amirz98/shecanman/issues

VRESION="0.3.0"

SHEACN_DNS_ARRAY=("178.22.122.100" "185.51.200.2")

SHECAN_DNS="# Shecan dns server
nameserver 178.22.122.100
nameserver 185.51.200.2"

SHECAN_DNS_NETWORKMANAGER="# Shecan dns server
[global-dns-domain-*]
servers=178.22.122.100,185.51.200.2"

# check if stdout is a terminal
if test -t 1; then
  # see if it supports colors
  ncolors=$(tput colors)

  if test -n "$ncolors" && test $ncolors -ge 8; then
    bold="$(tput bold)"
    normal="$(tput sgr0)"
    red="$(tput setaf 1)"
    green="$(tput setaf 2)"
    yellow="$(tput setaf 3)"
  fi
fi

# Check if NetworkManager is running
if pgrep "NetworkManager" >/dev/null; then
  echo "using NetworkManager"
  networkmanager_running=true
  # store path to dns files since they are used many times
  dns_file="/etc/NetworkManager/conf.d/dns-servers.conf"
  dns_file_backup="/etc/NetworkManager/conf.d/dns-servers.conf.backup"
else
  networkmanager_running=false
fi

function show_usage() {
  echo -e "
╭━━━┳╮╱╱╱╱╱╱╱╱╱╱╱╱╱╭━╮╭━╮
┃╭━╮┃┃╱╱╱╱╱╱╱╱╱╱╱╱╱┃┃╰╯┃┃
┃╰━━┫╰━┳━━┳━━┳━━┳━╮┃╭╮╭╮┣━━┳━╮
╰━━╮┃╭╮┃┃━┫╭━┫╭╮┃╭╮┫┃┃┃┃┃╭╮┃╭╮╮
┃╰━╯┃┃┃┃┃━┫╰━┫╭╮┃┃┃┃┃┃┃┃┃╭╮┃┃┃┃
╰━━━┻╯╰┻━━┻━━┻╯╰┻╯╰┻╯╰╯╰┻╯╰┻╯╰╯

ShecanMan lets you switch on/off Shecan.ir DNS configs temporarily on linux.

Usage: ${bold}shecanman [${green}command${normal}]

Commands:
${bold}${green} on      \t${normal}Switch on Shecan DNS configs; keeps a backup of current configs
${bold}${green} off     \t${normal}Switch off Shecan DNS; This will restore previous DNS configs
${bold}${green} status  \t${normal}Show current status; Check whether ShecanMan is on
${bold}${green} install \t${normal}Install ShecanMan system-wide, so you can call it everywhere
${bold}${green} uninstall \t${normal}Uninstall ShecanMan, so it's no longer accessible system-wide
${bold}${green} version \t${normal}Show ShecanMan version
${bold}${green} help    \t${normal}Show this help"
}

function exit_if_not_root() {
  if [[ $EUID -ne 0 ]]; then
    echo "${bold}${red} Permission denied. Please run as root.${normal}"
    exit 1
  fi
}

function is_shecan_on() {
  # read dns config file line by line
  while read -r line; do
    # ignore the line if does not begin with nameserver
    [[ ! $line =~ ^nameserver.* ]] && continue
    for shecan in "${SHEACN_DNS_ARRAY[@]}"; do
      if [[ "$line" =~ .*"$shecan".* ]]; then
        # found a valid shecan dns
        return 0
      fi
    done

    # only first valid line matters, so ignore others
    break
  done </etc/resolv.conf
  return 1
}

function switch_on() {
  if is_shecan_on; then
    echo "${bold}${green} Shecan is already in use.${normal}"
    return
  fi
  exit_if_not_root
  if $networkmanager_running; then
    # Check if dns file exists
    if [[ -f $dns_file ]]; then
      cp $dns_file $dns_file_backup
    fi
    echo -e "$SHECAN_DNS_NETWORKMANAGER" >$dns_file
    systemctl restart NetworkManager
  else
    cp /etc/resolv.conf /etc/resolv.conf.backup
    echo -e "$SHECAN_DNS" >/etc/resolv.conf
  fi
  echo "${bold}${green} Shecan DNS switched on.${normal}"
}

function switch_off() {
  if ! is_shecan_on; then
    echo "${bold}${green} Shecan is not in use.${normal}"
    return
  fi
  exit_if_not_root
  if $networkmanager_running; then
    # restore backup configs if exists
    if [[ -f $dns_file_backup ]]; then
      cp $dns_file_backup $dns_file
      rm $dns_file_backup
      systemctl restart NetworkManager
      echo "${bold}${green} Shecan DNS switched off.${normal}"
    else
      # Check if dns-servers.conf is using shecan
      if [[ $(head -n 1 $dns_file) == "# Shecan"* ]]; then
        rm $dns_file
        echo "${bold}${green} Shecan DNS switched off.${normal}"
      else
        echo "backup file not found you can verify entries in /etc/NetworkManager/conf.d/dns-servers.conf"
      fi
    fi
    systemctl restart NetworkManager
    return
  fi
  # restore backup configs if exists
  if [[ -f /etc/resolv.conf.backup ]]; then
    cp /etc/resolv.conf.backup /etc/resolv.conf
    rm /etc/resolv.conf.backup
    echo "${bold}${green} Shecan DNS switched off.${normal}"
    return
  fi
  # dns config backup file not found; this happens only when the user changes the dns configs manually
  # restruct a valid dns config based on current dns config file
  new_config="# Restored by ShecanMan\n"
  non_shecan_dns_count=0
  # read dns config file line by line, keep dns servers that are not for Shecan.ir
  while read -r line; do
    # ignore the line if does not begin with nameserver
    [[ ! $line =~ ^nameserver.* ]] && continue

    is_shecan_dns=1
    for shecan in "${SHEACN_DNS_ARRAY[@]}"; do
      if [[ "$line" =~ .*"$shecan".* ]]; then
        # found a non-shecan dns
        is_shecan_dns=0
        break
      fi
    done

    # keep the dns if it's not a shecan dns
    if [[ $is_shecan_dns == 1 ]]; then
      new_config+="$line\n"
      non_shecan_dns_count=$((non_shecan_dns_count + 1))
    fi
  done </etc/resolv.conf

  # if no non-shecan dns found, use Cloudflare dns server as a single dns entry
  if [[ $non_shecan_dns_count == 0 ]]; then
    new_config+="nameserver 1.1.1.1"
  fi

  # save the configs
  echo -e $new_config >/etc/resolv.conf

  if [[ $non_shecan_dns_count == 0 ]]; then
    echo "${bold}${yellow} Backup DNS not found! Notice that your DNS is now set to Cloudflare (1.1.1.1).${normal}"
  fi

  echo "${bold}${green} Shecan DNS switched off.${normal}"
}

function show_status() {
  if is_shecan_on; then
    echo "${bold}${green} Shecan is in use.${normal}"
  else
    echo "${bold}${green} Shecan is not in use.${normal}"
  fi
}

function install() {
  exit_if_not_root
  chmod +x shecanman
  mkdir -p /usr/local/bin
  cp shecanman /usr/local/bin/
  cp shecanman /usr/sbin/
  echo "${bold}${green} Congratulations! shecanman now is accessible everywhere.${normal}"
  if ! is_shecan_on; then
    echo "${bold}${green} Use [shecanman on] to switch on Shecan.ir DNS configs.${normal}"
  fi
}

function uninstall() {
  exit_if_not_root
  if is_shecan_on; then
    switch_off
  fi

  if [ -f /usr/local/bin/shecanman ]; then
    rm /usr/local/bin/shecanman
  fi
  echo "${bold}${green} shecanman uninstalled successfully.${normal}"
}

function show_version() {
  echo "${bold}${green} ShecanMan v$VRESION ${normal}"
}

function main() {
  case "$1" in
  "on") switch_on ;;
  "off") switch_off ;;
  "status") show_status ;;
  "install") install ;;
  "uninstall") uninstall ;;
  "version") show_version ;;
  *) show_usage ;;
  esac
}

main "$@"