gh-87497: Explicit that headers sent in camel-case

[axel3rd]

Refers: #87497

---

Currently, the Request sends header keys in Camel case.

This is a choice strategy (no problem with that) and even if headers should be considered insensitively RFC 7230 - 3.2. Header Fields, this is not always the case.

The fact that header keys are "rewritten" (in Camel case) could occurs complexity in troubleshooting (sample).

Having a note/mention about that in documentation would be nice.

---

Proof

Consider a server which write headers as it:

#!/usr/bin/env python3

import http.server as SimpleHTTPServer
import socketserver as SocketServer
import logging

PORT = 8000

class GetHandler(
        SimpleHTTPServer.SimpleHTTPRequestHandler
        ):

    def do_GET(self):
        logging.error(self.headers)
        SimpleHTTPServer.SimpleHTTPRequestHandler.do_GET(self)


Handler = GetHandler
httpd = SocketServer.TCPServer(("", PORT), Handler)

httpd.serve_forever()

Check that headers are written as it: curl --header "x-soMe-hEad: test" http://localhost:8000

Consider a simple usage request call with a custom header X-SoMe-hEader:

#!/usr/bin/env python3

import urllib.request

url = "http://localhost:8000"
hdr = { 'X-SoMe-hEader' : 'foobar' }

req = urllib.request.Request(url, headers=hdr)
response = urllib.request.urlopen(req)
response.read()

Result is: X-Some-Header: foobar

https://bugs.python.org/issue43331

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[axel3rd]

Our records indicate the following people have not signed the CLA:

I have signed it 26 févr. à 19:47 😢 :

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[axel3rd]

If any modification could be required on this PR, feel free to say it to me.

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[axel3rd]

If any modification could be required on this PR, feel free to say it to me.

[MaxwellDupre]

Thats not what I get after running
response.read()

b'\n\n\n<meta http-equiv="C...
Then a directory listing of where I am running the server script. Same running curl also.
Can you show exactly from star to finish, please?

[axel3rd]

@MaxwellDupre The header result is to check in "server side", written by logging.error(self.headers)

Hope this screen can help:

[JelleZijlstra]

Are there unit tests for this behavior? If not, we should add them if we choose to document it.

[axel3rd]

Doc updated, onboarding unit test process in progress.

[axel3rd]

@JelleZijlstra Doc fixed & UT added, let me know if it is OK for you.

[miss-islington]

Thanks @axel3rd for the PR, and @JelleZijlstra for merging it 🌮🎉.. I'm working now to backport this PR to: 3.9, 3.10.
🐍🍒⛏🤖

[bedevere-bot]

GH-91517 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

GH-91518 is a backport of this pull request to the 3.9 branch.