Summary

From #1164:

The comments for get_environment_proxies implies that CIDRs are supported in the NO_PROXY environment variable:

        # NO_PROXY=.google.com is marked as "all://*.google.com,
        #   which disables "www.google.com" but not "google.com"
        # NO_PROXY=google.com is marked as "all://*google.com,
        #   which disables "www.google.com" and "google.com".
        #   (But not "wwwgoogle.com")
        # NO_PROXY can include domains, IPv6, IPv4 addresses and "localhost"
        #   NO_PROXY=example.com,::1,localhost,192.168.0.0/16

Unfortunately, they aren't actually respected. If you use the NO_PROXY string from the comment, and connect to http://192.168.0.10, it will still attempt to go through the proxy.

The NO_PROXY string is currently being properly translated to a URLPattern (e.g. 192.168.0.0/16 => all://192.168.0.0/16), but the URLPattern matcher doesn't handle the CIDR.

This PR is an attempt to fix the matching logic.

Unit tests provide full code coverage. scripts/test passes. As an additional sanity check, this used to fail with "connection refused" since the proxy doesn't exist, but now works on my branch:

HTTPS_PROXY=http://localhost:12345 NO_PROXY=10.128.0.0/16 python -c "import httpx2; httpx2.get('https://10.128.11.39/')"

The most questionable part of this PR is how URLPattern ordering should work. "Check smaller ranges before larger ranges" seems reasonable. "IP addresses & ranges before hosts" seemed like basically a coin flip, so I just picked one.

This is my first PR to httpx2, so if I violated any conventions or you'd like any changes, just let me know. Thanks!

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

Since this brings the behavior in line with the documentation (or at least the comments), and I don't see any references to NO_PROXY in the docs, I skipped this step. If you'd like a change added, just let me know.