Proof of concept: client-side logout

Signed-off-by: Margo Crawford <margaretc@vmware.com>

pkg/oidcclient/filesession/cachefile.go

@@ -1,4 +1,4 @@
-// Copyright 2020 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2022 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 // Package cachefile implements the file format for session caches.
@@ -152,6 +152,19 @@ func (c *sessionCache) lookup(key oidcclient.SessionCacheKey) *sessionEntry {
 	return nil
 }
 
+// delete a cache entry by key. Returns whether it successfully deleted an entry.
+func (c *sessionCache) delete(key oidcclient.SessionCacheKey) bool {
+	length := len(c.Sessions)
+	for i := range c.Sessions {
+		if reflect.DeepEqual(c.Sessions[i].Key, key) {
+			c.Sessions[i] = c.Sessions[length-1]
+			c.Sessions = c.Sessions[:length-1]
+			return true
+		}
+	}
+	return false
+}
+
 // insert a cache entry.
 func (c *sessionCache) insert(entries ...sessionEntry) {
 	c.Sessions = append(c.Sessions, entries...)

pkg/oidcclient/filesession/filesession.go

@@ -1,4 +1,4 @@
-// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2022 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 // Package filesession implements a simple YAML file-based login.sessionCache.
@@ -113,6 +113,22 @@ func (c *Cache) PutToken(key oidcclient.SessionCacheKey, token *oidctypes.Token)
 	})
 }
 
+// DeleteToken deletes the token from the session cache at the given cache cache key.
+// It returns whether it deleted a token.
+func (c *Cache) DeleteToken(key oidcclient.SessionCacheKey) bool {
+	_, err := os.Stat(c.path)
+	if errors.Is(err, os.ErrNotExist) {
+		// if the cache file doesn't exist there's no session info
+		// to delete
+		return false
+	}
+	deleted := false
+	c.withCache(func(cache *sessionCache) {
+		deleted = cache.delete(key)
+	})
+	return deleted
+}
+
 // withCache is an internal helper which locks, reads the cache, processes/mutates it with the provided function, then
 // saves it back to the file.
 func (c *Cache) withCache(transact func(*sessionCache)) {