Regex not giving expected result in python

Question

I wrote this regex in an online editor and it was working properly there, but whenever I copy it to python, it can't find what I need anymore. Here is my code:

import requests
import re
import os

PAYLOAD = {
    "username": os.environ['USERNAME'],
    "password": os.environ['PASSWORD']
}

LOGIN_URL = "https://ringzer0ctf.com/login"
CHALLENGE_URL = "https://ringzer0ctf.com/challenges/32"

MESSAGE_REG_EX = r"(BEGIN MESSAGE -----<br \/>\n\n\t\t)(\d*)"

with requests.session() as session:
    session.post(LOGIN_URL, data=PAYLOAD)
    r = session.get(CHALLENGE_URL)
    print(r.text)
    num = re.search(MESSAGE_REG_EX, r.text).group(2)
    print(num)

I need to extract the first number between BEGIN MESSAGE and END MESSAGE which in this case is 6907.

    <div class="challenge-wrapper">

                <div class="padding_div">

        </div>

        <strong>You have 2 seconds to send the answer</strong><br />

        <strong>Send the answer back using https://ringzer0ctf.com/challenges/32/[answer]</strong>

        <br /><br /><br /><br /><br />

        <div class="message">

        ----- BEGIN MESSAGE -----<br />

        6907 + 0x1d68 - 1010001001100 = ?<br />

        ----- END MESSAGE -----<br />

        </div>

    </div>



<hr />

Error message:

num = re.search(MESSAGE_REG_EX, r.text).group(2) AttributeError: 'NoneType' object has no attribute 'group'

try MESSAGE_REG_EX = r"(?s)(BEGIN MESSAGE -{3,}<br\s*\/>\s*)(\d+)" — Avinash Raj
– Avinash Raj, Commented Aug 13, 2019 at 11:18
I think the problem is with whitespace: r"(BEGIN MESSAGE -----<br />\n\s*)(\d+)" should work. Note there is no point escaping /, it is not any special metacharacter. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 13, 2019 at 11:19

Avinash Raj · Accepted Answer · 2019-08-13 11:26:22Z

1

Maybe - or spaces got outnumbered. Give a try to below regex,

MESSAGE_REG_EX = r"BEGIN MESSAGE -{3,}<br\s*\/>\s*(\d+)" 
match = re.search(MESSAGE_REG_EX, r.text)
if match:
    print (match.group(1))
else:
    print('Failed to find a match :(')

edited Aug 13, 2019 at 11:26

answered Aug 13, 2019 at 11:19

Avinash Raj

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1 Comment

Wiktor Stribiżew Over a year ago

(?s) is redundant here. \/ = /. Basically, I'd suggest using a single capturing group and access its value with .group(1), OP is not interested in the BEGIN MESSAGE... part. And it is a good idea to show OP how to write code to avoid AttributeError: 'NoneType' object has no attribute 'group' exceptions upon no match.

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