Module Netmech_digest_sasl.DIGEST_MD5

Whether the client sends the first message:

• `Required: always
• `Optional: the client may choose to do so if the protocol permits this
• `No: the server sends the first message

Whether final data from the server must be interpreted by the mechanism

whether the authorization name can be transmitted

Whether the mechanism is available, in particular whether the required crypto support is linked in

Supply the mechanism with credentials. These are given as list (type,value,params). The mechanism may pick any element of this list which are considered as equivalent.

Types are defined per mechanism. All mechanisms understand the "password" type, which is just the cleartext password, e.g.

            [ "password", "ThE sEcReT", [] ]
          

Another common type is derived from the LDAP authPassword scheme (RFC 3112):

             [ "authPassword-" ^ scheme, authValue, [ "info", authInfo ] ]
          

The "info" attribute is optional. For instance, if you want to provide MD5-hashed passwords:

             [ "authPassword-MD5", hashed_password, [ "info", salt ] ]

          

Another common type is derived from the (older) LDAP userPassword scheme (RFC 2307):

            [ "userPassword-" ^ scheme, value, [] ]
         

More information can be found here: Credentials.sasl

Create a new server session. The lookup function is used to get the credentials for a given user name and a given authorization name (which is the empty string if not applicable). If the lookup function returns None, the user can either not be found, or the user does not have the privileges for the authorization name.

User name and authorization name are passed in UTF-8 encoding.

The parameters are given as list (name,value,critical). Critical parameters must be interpreted by the mechanism, and unknown critical parameters must be rejected by a Failure exception. Non-critical parameters are ignored if they are unknown to the mechanism.

Configures acceptable channel bindings wiht a list of pairs (type,data).

Process the response from the client. This function must generally only be called when the session state is `Wait. As an exception, however, this function may also be invoked with the initial client response, even if the session state is `Emit, so far the mechanism permits at least optionally that the client starts the protocol.

Process the response from the client when another session can be continued. The string argument is the initial client response. This function must only be called when the state reaches `Restart id after server_process_response, and in this case the old session with id can be restarted. This function should be called with the same message string as server_process_repsonse was just called with.

If the bool arg is true, a stale response is created. This is a special restart which forces the client to run through the authentication process again, although everything else was successful. (If the protocol does not support the stale flag, it is silently ignored.)

Returns true if the restart is successful. If not, false is returned. In this case, the server_session object can (and should) still be used, but the caller must treat it as new session. In particular, the session ID may change.

All in all, the idea of this function is best illustrated by this authentication snippet how to process responses (the session cache functions need to be written by the user of this module):

  let update_cache() =
    match server_session_id session with
      | None -> ()
      | Some id ->
          replace_in_session_cache id (server_stash_session session) in

  let rec check_state_after_response() =
    match server_state session with
      | `Restart id ->
           let old_session_s, time = find_in_session_cache id in
           let old_session = server_resume_session ~lookup old_session_s in
           let set_stale = current_time - time > limit in
           let session, cont =
             server_process_response_restart session msg set_stale in
           if not cont then 
             delete_in_session_cache id;
           (* Now check server_state again, should be `Emit now *)
           check_state_after_response()
      | `Emit ->
           let session, out_msg = server_emit_challenge session in
           update_cache();
           ...
      | ... ->
  in
  server_process_response session msg;

          

Emit a server challenge. This function must only be called when the session state is `Emit.

Serializes the session as string

Unserializes the session, and connect with the lookup function.

Optionally return a string that can be used to identify the server session. Not all mechanisms support this.

Get a mechanism-specific property of the session. E.g. this can be the "digest-uri" sent by the client.

The name the client has authenticated as (or Not_found)

The name the client authorizes as (or Not_found)

Whether the client suggests or demands channel binding

Return the GSSAPI properties of the server, after the authentication is successful (and raises Not_found up to then).

The new client session authenticate as user and authorizes as authz (empty string if not applicable). The credentials are creds.

user and authz must be encoded in UTF-8.

The parameters are given as list (name,value,critical). Critical parameters must be interpreted by the mechanism, and unknown critical parameters must be rejected by a Failure exception. Non-critical parameters are ignored if they are unknown to the mechanism.

Configure GS2-style channel binding

Restart the session for another authentication round. The session must be in state `OK.

Process the challenge from the server. The state must be `Wait. As an exception, this function can also be called for the initial challenge from the server, even if the state is `Emit.

Emit a new response. The state must be `Emit.

Whether the client suggests or demands channel binding

The user name

The authorization name

Serializes the session as string

Unserializes the session

Optionally return a string that can be used to identify the client session. Not all mechanisms support this.

Get a mechanism-specific property of the session. E.g. this can be the "realm" sent by the server.

Return the GSSAPI properties of the client, after the authentication is successful (and raises Not_found up to then).