Support loading keys and certificates as variables (bytes) in particular in the load_cert_chain function

Proposal:

In MutualTLS Authentication scenarios it's useful to maintain client credential (private_key) confidentiality by allowing loading of the credential from encrypted key archives for example PKCS12. Python Cryptography and other modules allow loading of private keys into memory and at present we need to write those sensitive files to disk temporarily in order to load them into our TLS Client context.

This appears to be the existing code https://github.com/python/cpython/blob/a9c304cf020e2fa3ae78fd88359dfc808c9dd639/Modules/_ssl.c#L3899

    if (keyfile && !PyUnicode_FSConverter(keyfile, &keyfile_bytes)) {
        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
            PyErr_SetString(PyExc_TypeError,
                            "keyfile should be a valid filesystem path");
        }
        goto error;
    }

Has this already been discussed elsewhere?

There is one somewhat similar feature request relating to loading from PKCS11 tokens. This is not related.

Links to previous discussion of this feature:

No response

從 Modules/_ssl.c 中的 load_cert_chain 實作以及 issue 中所示的檔案系統路徑轉換開始。檢視目前的函式如何接受金鑰和憑證路徑，然後確定記憶體中字節輸入所需的 API 和測試涵蓋範圍。當憑證資料可以從字節載入而不需要暫存敏感檔案時，即表示完成。