Tasks

• – canHandle:

  Can the presented challenge be potentially handled by this challenge handler?

• – handle:

  Handle the presented challenge by creating a challenge response or returning nil. This responsibility is usually achieved by using the associated KGLoginHandler to obtain user credentials, and transforming those credentials into a KGChallengeResponse.

  When it is not possible to create a KGChallengeResponse, this method MUST return nil.

• – registerChallengeHandler:challengeHandler:

  Register a challenge handler to respond to challenges at one or more locations.

  When a challenge response is received for a protected URI, the locationDescription matches against elements of the protected URI; if a match is found, one consults the challenge handler(s) registered at that locationDescription to find a challenge handler suitable to respond to the challenge.

  A locationDescription comprises a username, password, host, port and paths, any of which can be wild-carded with the “*” character to match any number of request URIs. If no port is explicitly mentioned in a locationDescription, a default port will be inferred based on the scheme mentioned in the location description, according to the following table:

  scheme	default port	Sample locationDescription
  http	80	foo.example.com or http://foo.example.com
  ws	80	foo.example.com or ws://foo.example.com
  https	443	https://foo.example.com
  wss	443	wss://foo.example.com

  The protocol scheme (e.g. http or ws) if present in locationDescription will not be used to match locationDescription with the protected URI, because authentication challenges are implemented on top of one of the HTTP/s protocols always, whether one is initiating web socket connections or regular HTTP connections. That is to say for example, the locationDescription "foo.example.com" matches both URIs http://foo.example.com and ws://foo.example.com.

  Some examples of locationDescription values with wildcards are:

  1. */ — matches all requests to any host on port 80 (default port), with no user info or path specified.
  2. *.hostname.com:8000 — matches all requests to port 8000 on any sub-domain of hostname.com, but not hostname.com itself.
  3. server.hostname.com:*/* — matches all requests to a particular server on any port on any path but not the empty path.

• – unregisterChallengeHandler:challengeHandler:

  If the provided challengeHandler is registered at the provided location, clear that association such that any future challenge requests matching the location will never be handled by the provided challenge handler.

  If no such location or challengeHandler registration exists, this method silently succeeds.