python 请求 'certificate verify failed' 以获得特定的 SNI 证书

Question

多年来，我几乎所有项目都使用 python 请求框架，从未遇到过这样的问题。

据我所知，这种情况只发生在 www.pagedna.com 网站上。要重现的代码示例非常简单

import requests
requests.get("https://www.pagedna.com")

Chrome/Firefox 浏览器打开这个网站，没问题，但上面的代码片段给了我一般的 SSL 失败异常

Traceback (most recent call last):
  File "inline.py", line 2, in <module>
    requests.get("https://www.pagedna.com")
  File "/home/rishi/workspace/misc/venvs/mc3.4/lib/python3.4/site-packages/requests/api.py", line 75, in get
    return request('get', url, params=params, **kwargs)
  File "/home/rishi/workspace/misc/venvs/mc3.4/lib/python3.4/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/rishi/workspace/misc/venvs/mc3.4/lib/python3.4/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/rishi/workspace/misc/venvs/mc3.4/lib/python3.4/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/rishi/workspace/misc/venvs/mc3.4/lib/python3.4/site-packages/requests/adapters.py", line 514, in send
    raise SSLError(e, request=request)
requests.exceptions.SSLError: HTTPSConnectionPool(host='www.pagedna.com', port=443): Max retries exceeded with url: / (Caused by SSLError(SSLError("bad handshake: Error([('SSL routines', 'tls_process_server_certificate', 'certificate verify failed')],)",),))

如果我使用服务器名参数，OpenSSL 会给我正确的信息

openssl s_client -showcerts -servername www.pagedna.com -connect www.pagedna.com:443

CONNECTED(00000003)
---
Certificate chain
 0 s:/OU=Domain Control Validated/CN=*.pagedna.com
   i:/C=US/ST=Arizona/L=Scottsdale/O=GoDaddy.com, Inc./OU=http://certs.godaddy.com/repository//CN=Go Daddy Secure Certificate Authority - G2
-----BEGIN CERTIFICATE-----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etc...

但是，如果缺少 -servername 选项，它会给我一个不同的证书，我怀疑这是这里的问题。

相关pip安装如下

pyOpenSSL==19.0.0
requests==2.21.0
requests-toolbelt==0.8.0

使用python3.4

这是一个请求框架错误吗？我应该打开错误报告还是遗漏了什么？

Answer 1

... but the snippet above gives me the generic SSL failure exception ...

 ...'tls_process_server_certificate', 'certificate verify failed')],)",),))

实际上，这不是一般的 SSL 故障。它显然失败了，因为它无法验证证书。原因不是 SNI 与非 SNI，因为 SNI 长期以来在请求中默认使用。

原因是服务器配置错误。来自SSLLabs report :

This server's certificate chain is incomplete. Grade capped to B.

Chrome/Firefox browsers open this site up, no problem ...

桌面浏览器通常可以成功解决这种常见的错误配置，例如通过缓存来自其他连接的中间证书并使用它们来填充证书链的缺失部分。但是，如果您尝试使用新配置文件的 Firefox，您将遇到同样的 SSL 问题。