1 /* 2 * 3 * Copyright 2018 gRPC authors. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 19 #ifndef GRPC_CORE_TSI_SSL_SESSION_CACHE_SSL_SESSION_CACHE_H 20 #define GRPC_CORE_TSI_SSL_SESSION_CACHE_SSL_SESSION_CACHE_H 21 22 #include <grpc/support/port_platform.h> 23 24 #include <grpc/slice.h> 25 #include <grpc/support/sync.h> 26 27 extern "C" { 28 #include <openssl/ssl.h> 29 } 30 31 #include "src/core/lib/avl/avl.h" 32 #include "src/core/lib/gprpp/memory.h" 33 #include "src/core/lib/gprpp/ref_counted.h" 34 #include "src/core/lib/gprpp/sync.h" 35 #include "src/core/tsi/ssl/session_cache/ssl_session.h" 36 37 /// Cache for SSL sessions for sessions resumption. 38 /// 39 /// Older sessions may be evicted from the cache using LRU policy if capacity 40 /// limit is hit. All sessions are associated with some key, usually server 41 /// name. Note that servers are required to share session ticket encryption keys 42 /// in order for cache to be effective. 43 /// 44 /// This class is thread safe. 45 46 namespace tsi { 47 48 class SslSessionLRUCache : public grpc_core::RefCounted<SslSessionLRUCache> { 49 public: 50 /// Create new LRU cache with the given capacity. Create(size_t capacity)51 static grpc_core::RefCountedPtr<SslSessionLRUCache> Create(size_t capacity) { 52 return grpc_core::MakeRefCounted<SslSessionLRUCache>(capacity); 53 } 54 55 // Use Create function instead of using this directly. 56 explicit SslSessionLRUCache(size_t capacity); 57 ~SslSessionLRUCache() override; 58 59 // Not copyable nor movable. 60 SslSessionLRUCache(const SslSessionLRUCache&) = delete; 61 SslSessionLRUCache& operator=(const SslSessionLRUCache&) = delete; 62 63 /// Returns current number of sessions in the cache. 64 size_t Size(); 65 /// Add \a session in the cache using \a key. This operation may discard older 66 /// sessions. 67 void Put(const char* key, SslSessionPtr session); 68 /// Returns the session from the cache associated with \a key or null if not 69 /// found. 70 SslSessionPtr Get(const char* key); 71 72 private: 73 class Node; 74 75 Node* FindLocked(const grpc_slice& key); 76 void Remove(Node* node); 77 void PushFront(Node* node); 78 void AssertInvariants(); 79 80 grpc_core::Mutex lock_; 81 size_t capacity_; 82 83 Node* use_order_list_head_ = nullptr; 84 Node* use_order_list_tail_ = nullptr; 85 size_t use_order_list_size_ = 0; 86 grpc_avl entry_by_key_; 87 }; 88 89 } // namespace tsi 90 91 #endif /* GRPC_CORE_TSI_SSL_SESSION_CACHE_SSL_SESSION_CACHE_H */ 92