[tompollard]

Fixes a 500 error seen in production on /authorcid/:

MissingTokenError at /authorcid/
(missing_token) Missing access token parameter.
  user/views.py in _fetch_and_validate_token: token = oauth_session.fetch_token(...)

Cause

When someone links (or logs in with) ORCID, the server exchanges the code from ORCID for a token. _fetch_and_validate_token only caught InvalidGrantError, which is what a standard rejection such as an expired or reused code raises. Two other cases weren't caught, and both gave the user a 500:

• A reply with no token and no OAuth error, such as an HTML error page from ORCID or a proxy, an empty body, or a rate-limit page. oauthlib raises MissingTokenError for these. That's what happened here; a standard rejection would have raised InvalidGrantError instead.
• ORCID can't be reached: a connection error or timeout raises a requests exception.

We can't tell what ORCID actually sent, because the reply wasn't logged.

Changes

• Errors are caught: _fetch_and_validate_token now also catches OAuth2Error and requests.RequestException. The user is sent back to the ORCID settings page (or the login page) with "ORCID did not respond as expected. Please try again in a few minutes."
• ORCID's reply is logged: a requests_oauthlib compliance hook keeps the reply. The log line has the status, the content type and the first 300 characters of the body. The body is left out if it contains "token", so a token can't end up in the logs.
• Nothing else changes: an expired or invalid code shows the same message as before, and token validation is the same. This covers ORCID linking and ORCID login, since both use this function.

Testing

• New tests in user/test_orcid.py:
  • the token endpoint returns a 502 HTML page when linking (the case from production): no 500, the retry message, nothing linked, and the log has the status and body
  • a reply that may contain a token isn't logged
  • ORCID can't be reached
  • the token endpoint returns a 503 when logging in with ORCID: no 500, and the user isn't logged in
• Checked against the old code: all four new tests error with the exceptions above. With the fix, all 53 ORCID tests pass.
• Full suite: passes except physionet.test_urls for the anonymous access URL of demoecg, which also fails on dev locally without this change.