| /* |
| * Copyright (C) 2018 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef _DNS_DNSTLSQUERYMAP_H |
| #define _DNS_DNSTLSQUERYMAP_H |
| |
| #include <future> |
| #include <map> |
| #include <mutex> |
| #include <vector> |
| |
| #include <android-base/thread_annotations.h> |
| #include <netdutils/Slice.h> |
| |
| #include "DnsTlsServer.h" |
| |
| namespace android { |
| namespace net { |
| |
| // Keeps track of queries and responses. This class matches responses with queries. |
| // All methods are thread-safe and non-blocking. |
| class DnsTlsQueryMap { |
| public: |
| struct Query { |
| // The new ID number assigned to this query. |
| uint16_t newId; |
| // A query that has been passed to recordQuery(), with its original ID number. |
| const netdutils::Slice query; |
| }; |
| |
| typedef DnsTlsServer::Response Response; |
| typedef DnsTlsServer::Result Result; |
| |
| struct QueryFuture { |
| QueryFuture(Query query, std::future<Result> result) |
| : query(query), result(std::move(result)) {} |
| Query query; |
| // A future which will resolve to the result of this query. |
| std::future<Result> result; |
| }; |
| |
| // Returns an object containing everything needed to complete processing of |
| // this query, or null if the query could not be recorded. |
| std::unique_ptr<QueryFuture> recordQuery(const netdutils::Slice query); |
| |
| // Process a response, including a new ID. If the response |
| // is not recognized as matching any query, it will be ignored. |
| void onResponse(std::vector<uint8_t> response); |
| |
| // Clear all map contents. This causes all pending queries to resolve with failure. |
| void clear(); |
| |
| // Get all pending queries. This returns a shallow copy, mostly for thread-safety. |
| std::vector<Query> getAll(); |
| |
| // Mark a query has having been retried. If the query hits the retry limit, it will |
| // be expired at the next call to cleanup. |
| void markTried(uint16_t newId); |
| void cleanup(); |
| |
| // Returns true if there are no pending queries. |
| bool empty(); |
| |
| private: |
| std::mutex mLock; |
| |
| struct QueryPromise { |
| QueryPromise(Query query) : query(query) {} |
| Query query; |
| // Number of times the query has been tried. Limited to kMaxTries. |
| int tries = 0; |
| // A promise whose future is returned by recordQuery() |
| // It is fulfilled by onResponse(). |
| std::promise<Result> result; |
| }; |
| |
| // The maximum number of times we will send a query before abandoning it. |
| static constexpr int kMaxTries = 3; |
| |
| // Outstanding queries by newId. |
| std::map<uint16_t, QueryPromise> mQueries GUARDED_BY(mLock); |
| |
| // Get a "newId" number that is not currently in use. Returns -1 if there are none. |
| int32_t getFreeId() REQUIRES(mLock); |
| |
| // Fulfill the result with an error code. |
| static void expire(QueryPromise* _Nonnull p); |
| }; |
| |
| } // end of namespace net |
| } // end of namespace android |
| |
| #endif // _DNS_DNSTLSQUERYMAP_H |