BUG?: Sometimes `get_otpauth_url` generates a URL that Free-OTP cannot

[moggers87]

If the current site is hosted on a non-standard port, e.g. 8000 is used by Django's runserver command, get_otpauth_url will generate a URL that has multiple : in the label section which in turn causes FreeOTP to reject the token as invalid

Expected Behavior

The token is valid, FreeOTP accepts the URL/secret key via QR code and setup can be completed

Current Behavior

FreeOTP throws an error

Possible Solution

According to this document:

Neither issuer nor account name may themselves contain a colon

get_otpauth_url should either strip or replace additional colons

Steps to Reproduce (for bugs)

1. Start python manage.py runserver
2. Start 2FA setup
3. Scan the QR code with FreeOTP

Context

While investigating #767 I ran into this bug and it made going through setup multiple times more of a chore than was necessary.

Your Environment

• Browser and version: Firefox
• Python version: 3.12
• Django version: 5.2.1
• django-otp version: 1.6.0
• django-two-factor-auth version: 1.17.0
• Link to your project: https://github.com/jazzband/django-two-factor-auth

[moggers87]

Forgot to add an example QR code

The URL is otpauth://totp/127.0.0.1%3A8000%3A%20moggers?secret=YU44W5B7LRZSCMG7MBMXSKVC2XX6KAVL&digits=6&issuer=127.0.0.1%3A8000, where %3A is an encoded colon

[faxioman]

It also fails with this qr code:

The URL is: otpauth://totp/rncem-193-207-168-174.a.free.pinggy.link%3A%20nuser?secret=RCD7OVNCPQDR3V7EGHU2FVEITV4ZZCAA&digits=6&issuer=rncem-193-207-168-174.a.free.pinggy.link