Fix: Django not detect that our site is HTTPS

[hongquan]

Fixes #267

Add SECURE_PROXY_SSL_HEADER settings. This guides Django to look into Nginx header to detect that our website is in HTTPS. We need this settings because the TLS termination is done on Nginx, not on Django, so Django originally cannot know if our site is HTTP or HTTPS.

How has this been tested?

This is the page where user see the link:

Before this PR, user will see this after clicking the link:

User no longer sees this page after this PR.

Checklist

• I have added tests to cover my changes.

Summary by Sourcery

Bug Fixes:

• Fixes an issue where Django was unable to detect that the site was being served over HTTPS due to TLS termination occurring at the Nginx proxy level.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request fixes an issue where Django was not correctly detecting HTTPS connections due to TLS termination at the Nginx proxy. It introduces the SECURE_PROXY_SSL_HEADER setting to address this. Additionally, type hints were added to the redirect view.

Sequence diagram for HTTPS redirection with Nginx proxy

sequenceDiagram
    actor User
    participant Browser
    participant Nginx
    participant Django

    User->>Browser: Clicks on a link
    Browser->>Nginx: HTTPS Request to the site
    Nginx->>Django: Forwards request with X-Forwarded-Proto header
    Django->>Django: Reads SECURE_PROXY_SSL_HEADER setting
    Django->>Django: Detects HTTPS based on header
    Django-->>Nginx: HTTPS Response
    Nginx-->>Browser: HTTPS Response
    Browser-->>User: Renders page securely

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File-Level Changes

Change	Details	Files
Configured Django to recognize HTTPS connections when TLS termination occurs at the Nginx proxy level.	Added SECURE_PROXY_SSL_HEADER to inform Django to trust the HTTP_X_FORWARDED_PROTO header set by Nginx. Set the value of SECURE_PROXY_SSL_HEADER to ('HTTP_X_FORWARDED_PROTO', 'https').	src/pretalx/settings.py
Added type hints to the redirect view.	Added type hints to the request parameter of the _is_samesite_referer function. Added type hints to the return value of the _is_samesite_referer function. Added type hints to the request parameter of the redirect_view function. Added type hints to the return value of the redirect_view function. Added type hints to the url parameter of the safelink function. Added type hints to the return value of the safelink function.	src/pretalx/common/views/redirect.py

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#267	Remove the outbound link warning/redirect page.	✅

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[sourcery-ai]

Hey @hongquan - I've reviewed your changes - here's some feedback:

Overall Comments:

• It might be worth adding a comment explaining why SECURE_PROXY_SSL_HEADER is needed.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[hongquan]

@sourcery-api The explanation comment is right on top of SECURE_PROXY_SSL_HEADER.

[norbusan]

The changes look ok, but please do not mix two different things.
This PR now contains:

• the described fix to add SECURE_PROXY_SSL_HEADER
• unrelated typing changes