default port for the socks5h scheme

[mateuszlitwin]

Summary

This change is needed to unblock encode/httpx#3178 and support socks5h scheme (server-side hostname resolution socks5 proxy). Support for the socks5h is needed to ensure global environment variables like all_proxy="socks5h://..." can be used reliably with different programs (some of which are httpx based).

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.

[mateuszlitwin]

Can add sync and async tests for httpcore.SOCKSProxy with socks5h scheme if needed.

[tomchristie]

Thanks. Do you know implementation would need to change in establishing the connection in socks_proxy.py?

[mateuszlitwin]

I don't think so:

• I tested test_socks_proxy.py with socks5h scheme and tests passed. Happy to update these tests to test both schemes if you think it is worth it.
• I tested this change with add socks5h proxy support httpx#3178 with real proxies.

[tomchristie]

We do already use "proxy resolves the hostname" behaviour, so our SOCKS support is "sock5h".

https://superuser.com/questions/1762341/does-chromium-not-support-socks5h-with-the-h-in-the-end

It's not obvious that we should add a synonym to the protocol name. (Staying in line with chromium's behaviour here seems reasonable, perhaps?)

[mateuszlitwin]

It is true that httpx already does proxy side hostname resolution, but other tools do not. For instance, curl does not for the socks5 scheme. See also libraries like urllib3 and libcurl (https://curl.se/libcurl/c/CURLOPT_PROXY.html). This makes it impossible to set global env like all_proxy="socks5h://127.0.0.1:1080" to correctly support server-side-resolution proxy in multiple tools.

[tomchristie]

Okay yep.
Looks like there's a linter failure needs resolving...

+ ruff format httpcore tests --diff
1 file would be reformatted, 37 files already formatted
--- tests/test_models.py
+++ tests/test_models.py
@@ -47,7 +47,9 @@
     assert str(url.origin) == "socks5://[12](https://github.com/encode/httpcore/actions/runs/11522347142/job/32078024585?pr=972#step:5:13)7.0.0.1:1080"
 
     url = httpcore.URL("socks5h://127.0.0.1")
-    assert url.origin == httpcore.Origin(scheme=b"socks5h", host=b"127.0.0.1", port=1080)
+    assert url.origin == httpcore.Origin(
+        scheme=b"socks5h", host=b"127.0.0.1", port=1080
+    )
     assert str(url.origin) == "socks5h://127.0.0.1:1080"

[mateuszlitwin]

I think you are looking at the wrong revision?

[tomchristie]

Okay, yep.
Thanks! 🙏🏼

[mateuszlitwin]

@tomchristie Could you revisit encode/httpx#3178 after merging this PR? I think this might have been the blocker.