logical/framework: simplify calculation of lease renew

logical/framework/lease.go

@@ -13,7 +13,7 @@ import (
 // setting it to 2 hours forces a renewal within the next 2 hours again.
 //
 // maxSession is the maximum session length allowed since the original
-// issue time. If this is zero, it is ignored,.
+// issue time. If this is zero, it is ignored.
 func LeaseExtend(max, maxSession time.Duration) OperationFunc {
 	return func(req *logical.Request, data *FieldData) (*logical.Response, error) {
 		lease := detectLease(req)
@@ -21,55 +21,44 @@ func LeaseExtend(max, maxSession time.Duration) OperationFunc {
 			return nil, fmt.Errorf("no lease options for request")
 		}
 
+		// Sanity check the desired increment
+		switch {
+		// Protect against negative leases
+		case lease.LeaseIncrement < 0:
+			return logical.ErrorResponse(
+				"increment must be greater than 0"), logical.ErrInvalidRequest
+
+		// If no lease increment, or too large of an increment, use the max
+		case max > 0 && lease.LeaseIncrement == 0, max > 0 && lease.LeaseIncrement > max:
+			lease.LeaseIncrement = max
+		}
+
+		// Get the current time
 		now := time.Now().UTC()
 
 		// Check if we're passed the issue limit
 		var maxSessionTime time.Time
 		if maxSession > 0 {
 			maxSessionTime = lease.LeaseIssue.Add(maxSession)
-			if maxSessionTime.Sub(now) <= 0 {
+			if maxSessionTime.Before(now) {
 				return logical.ErrorResponse(fmt.Sprintf(
 					"lease can only be renewed up to %s past original issue",
 					maxSession)), logical.ErrInvalidRequest
 			}
 		}
 
-		// Protect against negative leases
-		if lease.LeaseIncrement < 0 {
-			return logical.ErrorResponse(
-				"increment must be greater than 0"), logical.ErrInvalidRequest
-		}
-
-		// If the lease is zero, then assume max
-		if lease.LeaseIncrement == 0 {
-			lease.LeaseIncrement = max
-		}
-
-		// If the increment is greater than the amount of time we have left
-		// on our session, set it to that.
-		if !maxSessionTime.IsZero() {
-			diff := maxSessionTime.Sub(lease.ExpirationTime())
-			if diff < lease.LeaseIncrement {
-				lease.LeaseIncrement = diff
-			}
+		// The new lease is the minimum of the requested LeaseIncrement
+		// or the maxSessionTime
+		requestedLease := now.Add(lease.LeaseIncrement)
+		if !maxSessionTime.IsZero() && requestedLease.After(maxSessionTime) {
+			requestedLease = maxSessionTime
 		}
 
 		// Determine the requested lease
-		newLease := lease.IncrementedLease(lease.LeaseIncrement)
-
-		if max > 0 {
-			// Determine if the requested lease is too long
-			maxExpiration := now.Add(max)
-			newExpiration := now.Add(newLease)
-			if newExpiration.Sub(maxExpiration) > 0 {
-				// The new expiration is past the max expiration. In this
-				// case, admit the longest lease we can.
-				newLease = maxExpiration.Sub(lease.ExpirationTime())
-			}
-		}
+		newLeaseDuration := requestedLease.Sub(now)
 
 		// Set the lease
-		lease.Lease = newLease
+		lease.Lease = newLeaseDuration
 		return &logical.Response{Auth: req.Auth, Secret: req.Secret}, nil
 	}
 }
@@ -80,6 +69,5 @@ func detectLease(req *logical.Request) *logical.LeaseOptions {
 	} else if req.Secret != nil {
 		return &req.Secret.LeaseOptions
 	}
-
 	return nil
 }