1 /*
2  * Copyright (C) 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17 
18 #pragma once
19 
20 #include <deque>
21 #include <string>
22 #include <vector>
23 
24 #include <android-base/thread_annotations.h>
25 #include <netdutils/DumpWriter.h>
26 
27 namespace android::net {
28 
29 // A circular buffer based class used for query logging. It's thread-safe for concurrent access.
30 class DnsQueryLog {
31   public:
32     static constexpr std::string_view DUMP_KEYWORD = "querylog";
33 
34     struct Record {
RecordRecord35         Record(uint32_t netId, uid_t uid, pid_t pid, const std::string& hostname,
36                const std::vector<std::string>& addrs, int timeTaken)
37             : netId(netId),
38               uid(uid),
39               pid(pid),
40               hostname(hostname),
41               addrs(addrs),
42               timeTaken(timeTaken) {}
43         const uint32_t netId;
44         const uid_t uid;
45         const pid_t pid;
46         const std::chrono::system_clock::time_point timestamp = std::chrono::system_clock::now();
47         const std::string hostname;
48         const std::vector<std::string> addrs;
49         const int timeTaken;
50     };
51 
52     // Allow the tests to set the capacity and the validaty time in milliseconds.
53     DnsQueryLog(size_t size = kDefaultLogSize,
54                 std::chrono::milliseconds time = kDefaultValidityMinutes)
mCapacity(size)55         : mCapacity(size), mValidityTimeMs(time) {}
56 
57     void push(Record&& record) EXCLUDES(mLock);
58     void dump(netdutils::DumpWriter& dw) const EXCLUDES(mLock);
59 
60   private:
61     mutable std::mutex mLock;
62     std::deque<Record> mQueue GUARDED_BY(mLock);
63     const size_t mCapacity;
64     const std::chrono::milliseconds mValidityTimeMs;
65 
66     // The capacity of the circular buffer.
67     static constexpr size_t kDefaultLogSize = 200;
68 
69     // Limit to dump the queries within last |kDefaultValidityMinutes| minutes.
70     static constexpr std::chrono::minutes kDefaultValidityMinutes{60};
71 };
72 
73 }  // namespace android::net
74