Allow to load SSL certfile and keyfile from a file-like object

Feature or enhancement

Proposal:

# Have a look in commit 7c3ddb5
# It should be possible to also load certfile and keyfile from embedded certificate strings
cert_file = io.BytesIO(SERVER_CERT_STRING.encode('utf-8'))
key_file = io.BytesIO(SERVER_KEY_ENCRYPTED_STRING.encode('utf-8'))
context.load_cert_chain(certfile=cert_file, keyfile=key_file, password=key_pass)

https://github.com/python/cpython/commit/7c3ddb51b969fbfc022c8b6a5d1c1a3c6861d481

It should be possible to also load certfile and keyfile from embedded certificate strings. At the moment the code only reads the certificates from files (filepath). But when you don't want to have the saved/written certificates on the storage you should be able to load them from embedded strings.

Would it possible to include this code to the latest cpython? I tested this code from commit 7c3ddb5 with cpython v3.8.10 and here it almost has worked directly and only few lines had to be adapted. But I also tried it with the latest cpython version and here in Visual Studio there are some warnings. I don't know why this functionality isn't included in the master branch because it adds useful and advanced functionalities.

Has this already been discussed elsewhere?

https://github.com/python/cpython/issues/60691

Links to previous discussion of this feature:

https://github.com/python/cpython/compare/main...jgehrcke:cpython:jgehrcke/address-issue-16487-sept17

首先查看提交 7c3ddb5 和 issue 60691 中的讨论，然后检查当前的 SSLContext.load_cert_chain 实现及其测试。当包含嵌入字符串的证书和密钥类文件对象能够使用现有的密码处理方式被接受，并且为提议的 BytesIO 用法添加了覆盖时，此更改即完成。