34

The HTTP spec states:

10.4.2 401 Unauthorized

The request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.47) containing a challenge applicable to the requested resource.

If the only login scheme I support is OpenID (or CAS, or OAuth tokens, &c.), what should I put in this field? That is, how do I indicate that the client needs to pre-authenticate and create a session rather than try to send credentials along with each request?

Before you answer, "don't send a 401; send a 3xx redirecting to the OpenID login page," what about for non-HTML clients? How, for example, would Stack Overflow do an API that my custom software could interact with?

James A. Rosen
  • 64,193
  • 61
  • 179
  • 261

2 Answers2

26

According to RFC2617 the auth-scheme can be anything; if you really want a 401 you're not technically breaking spec by making something up like WWW-Authenticate: OpenID realm="My Realm" location="http://my/login/location". Having said that, behaviour of other people's code when you do that is of course undefined. :-)

Community
  • 1
  • 1
Chris Boyle
  • 11,423
  • 7
  • 48
  • 63
3

There is an OAuth Discovery spec that would indicate what to put into the WWW-Authenticate header -- if the spec were not obsolete without a replacement spec yet.

jpsecher
  • 4,461
  • 2
  • 33
  • 42
Andrew Arnott
  • 80,040
  • 26
  • 132
  • 171