Log DNS resolved answers
Introduce a thread-safe queue, DnsQueryLog, to log the DNS resolved answers
which are not found in the cache. The sensitive data is masked in order
not to reveal privacy information. The log can be shown only by
"dumpsys dnsresolver querylog", and it can show only the most-recent-one-hour
queries.
Example output:
DNS query log (last 60 minutes):
time=17:27:09.262 netId=100 uid=10107 pid=3322 hostname=w*** answer=[2404:***, 216.***] (33ms)
time=17:27:14.303 netId=100 uid=10097 pid=3363 hostname=w*** answer=[13.***] (21ms)
Bug: 139040977
Test: cd packages/modules/DnsResolver && atest
Test: "adb shell dumpsys dnsresolver querylog" passed
Change-Id: I8d063f4ac920f41c4fbc77e60a3e3a919d9daa62
diff --git a/DnsQueryLog.h b/DnsQueryLog.h
new file mode 100644
index 0000000..a319047
--- /dev/null
+++ b/DnsQueryLog.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2019 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.
+ *
+ */
+
+#pragma once
+
+#include <deque>
+#include <string>
+#include <vector>
+
+#include <android-base/thread_annotations.h>
+#include <netdutils/DumpWriter.h>
+
+namespace android::net {
+
+// A circular buffer based class used for query logging. It's thread-safe for concurrent access.
+class DnsQueryLog {
+ public:
+ static constexpr std::string_view DUMP_KEYWORD = "querylog";
+
+ struct Record {
+ Record(uint32_t netId, uid_t uid, pid_t pid, const std::string& hostname,
+ const std::vector<std::string>& addrs, int timeTaken)
+ : netId(netId),
+ uid(uid),
+ pid(pid),
+ hostname(hostname),
+ addrs(addrs),
+ timeTaken(timeTaken) {}
+ const uint32_t netId;
+ const uid_t uid;
+ const pid_t pid;
+ const std::chrono::system_clock::time_point timestamp = std::chrono::system_clock::now();
+ const std::string hostname;
+ const std::vector<std::string> addrs;
+ const int timeTaken;
+ };
+
+ void push(Record&& record) EXCLUDES(mLock);
+ void dump(netdutils::DumpWriter& dw) const EXCLUDES(mLock);
+
+ private:
+ mutable std::mutex mLock;
+ std::deque<Record> mQueue GUARDED_BY(mLock);
+
+ // The capacity of the circular buffer.
+ static constexpr size_t kLogSize = 200;
+
+ // Limit to dump the queries within last |kValidityMinutes| minutes.
+ static constexpr std::chrono::minutes kValidityMinutes{60};
+};
+
+} // namespace android::net