SERVER-30298 Add UserDigest LogicalSessionID

Inclusion of a sha256 digest of the full username to the logical session
id (in addition to the current guid) is necessary to fully disambiguate
logical sessions in degraded clusters (when the authoritative record for
a session is unreachable).

Semantics for the uid are as follows:

session creation via startSession()
* Sessions can only be created with one, and only one, user authenticated
* The composite key is created from a guid created on the spot, as well
  as the digest of the currently auth'd username
* Only the session guid is returned to the user
  * This prevents outside users from attempting to send back a value
    we'd have to check.  It's preferable to decorate the guid with the
    user digest per command, rather than having to check a value the user
    might send.

session use for a command
* Sessions are passed via the lsid top level field in any command
* Sessions are only meaningful for commands which requireAuth.  For
  sessions which don't require auth, we strip session information from the
  command at parse time
* Session ids are passed as an object, which can optionally include the
  username digest
  * It is illegal to pass the username digest unless the currently
    auth'd user has the impersonate privilege (the __system user does).
    This enables sessions on shard servers via mongos

1 files changed, 1 insertions, 3 deletions

diff --git a/src/mongo/db/sessions_collection.h b/src/mongo/db/sessions_collection.h
index 7692e634275..4a7503a293e 100644
--- a/src/mongo/db/sessions_collection.h
+++ b/src/mongo/db/sessions_collection.h
@@ -29,8 +29,6 @@
 #pragma once
 
 #include "mongo/db/logical_session_id.h"
-#include "mongo/db/logical_session_record.h"
-#include "mongo/db/signed_logical_session_id.h"
 
 namespace mongo {
 
@@ -48,7 +46,7 @@ public:
      * Returns a LogicalSessionRecord for the given session id. This method
      * may run networking operations on the calling thread.
      */
-    virtual StatusWith<LogicalSessionRecord> fetchRecord(SignedLogicalSessionId id) = 0;
+    virtual StatusWith<LogicalSessionRecord> fetchRecord(LogicalSessionId id) = 0;
 
     /**
      * Inserts the given record into the sessions collection. This method may run