websiteblocker.py

import time
import sys
import platform
import os
import psutil

#function to fetch the URLs that have been saved in urllist.txt for blocking
def fetchurls():
	urllist = list()
	with open('urllist.txt') as file :
		urllist = [line.rstrip() for line in file]
	return urllist

# Fetch URLs from the file
sites_to_be_blocked = fetchurls()
redirect = "127.0.0.1"

#identifying the underlying Operating System to decide the directory the hosts file resides in
#Currently working for Microsoft Windows, Linux Distributions and MacOS
if platform.system() == 'Windows':
    host_file = r"C:\Windows\System32\drivers\etc\hosts"
    firefox_profile = os.path.expanduser("~\\AppData\\Roaming\\Mozilla\\Firefox\\Profiles\\")
elif platform.system() == "Linux" or platform.system() == "darwin":
    host_file = "/etc/hosts"
    firefox_profile = os.path.expanduser("~/.mozilla/firefox/")
else:
    print("Expected your OS to be Windows, Linux or MacOS but found something else, hence quitting...")
    sys.exit(1)

# Function to disable DNS over HTTPS (DoH) in Firefox
def disable_firefox_doh():
    global firefox_profile
    if not os.path.exists(firefox_profile):
        print("Firefox profile directory not found.")
        return

    # Locate the correct Firefox profile folder
    for folder in os.listdir(firefox_profile):
        prefs_file = os.path.join(firefox_profile, folder, "prefs.js")
        if os.path.exists(prefs_file):
            try:
                with open(prefs_file, "r+") as file:
                    lines = file.readlines()
                    file.seek(0)
                    for line in lines:
                        # Remove existing DoH settings
                        if "network.trr.mode" not in line:
                            file.write(line)
                    # Append the new setting to force system DNS resolution
                    file.write('user_pref("network.trr.mode", 5);\n')
                    file.truncate()
                print("DNS over HTTPS (DoH) disabled in Firefox.")
            except Exception as e:
                print(f"Error modifying Firefox prefs.js: {e}")
            return
			

# Function to clear Firefox's DNS cache by restarting it
def restart_firefox():
    for proc in psutil.process_iter(['pid', 'name']):
        if "firefox" in proc.info['name'].lower():
            print("Restarting Firefox...")
            proc.terminate()
            time.sleep(2)  # Give Firefox time to close
            os.system("firefox &")  # Restart Firefox
            return

# Function to block sites by modifying the hosts file
def block(answer):
	while True:
		with open(host_file, 'r+') as hostentry:
			hosts = hostentry.read() #reading the host entries to confirm if the required URLs are present or not
			#adding the urls from DB in hosts file and adding redirection to localhost to make them inaccessible
			for url in sites_to_be_blocked:
				if url not in hosts:
					hostentry.write(redirect+' '+url+'\n')
		try:
			time.sleep(50)
		except KeyboardInterrupt:
			#catching the ctrl + c (quit) from user, asking for confirmation
			quitting = input("Do you really want to disable content blocking?[Y/y or N/n]")
			if (quitting == "Y" or quitting == "y"):
				#clearing the entries made during blocking phase
				with open(host_file, 'r+') as hostentry:
					hosts = hostentry.readlines()
					hostentry.seek(0)
					for host in hosts:
						if not any(url in host for url in sites_to_be_blocked):
							hostentry.write(host)
					hostentry.truncate()
				print("Cool!!\nhave a great time!")
				sys.exit(1)
			else:
				continue


if __name__ == '__main__':
    answer = input("Do you want to enable content filtering(you need to focus)?[Y/y or N/n]")

    if (answer == "Y" or answer == "y"):
        #calling the block() function to enable blocking
        print("Great\nFetching the blocked URLs from your Database(urllist.txt).")
        time.sleep(1)
        print("\nDefault blocking has been enabled as per request.")
		# Disable Firefox DoH & restart Firefox
        disable_firefox_doh()
        restart_firefox()
        block(answer)