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      1 /*
      2  * Copyright (C) 2017 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 #ifndef NETD_SERVER_IPTABLES_RESTORE_CONTROLLER_H
     18 #define NETD_SERVER_IPTABLES_RESTORE_CONTROLLER_H
     19 
     20 #include <memory>
     21 #include <mutex>
     22 #include <sys/types.h>
     23 
     24 #include "NetdConstants.h"
     25 
     26 class IptablesProcess;
     27 
     28 class IptablesRestoreController {
     29 public:
     30     // Not for general use. Use gCtls->iptablesRestoreCtrl
     31     // to get an instance of this class.
     32     IptablesRestoreController();
     33 
     34     // Execute |commands| on the given |target|.
     35     int execute(const IptablesTarget target, const std::string& commands);
     36 
     37     // Execute |commands| on the given |target|, and populate |output| with stdout.
     38     int execute(const IptablesTarget target, const std::string& commands, std::string *output);
     39 
     40     enum IptablesProcessType {
     41         IPTABLES_PROCESS,
     42         IP6TABLES_PROCESS,
     43         INVALID_PROCESS = -1,
     44     };
     45 
     46     // Called by the SIGCHLD signal handler when it detects that one
     47     // of the forked iptables[6]-restore process has died.
     48     IptablesProcessType notifyChildTermination(pid_t pid);
     49 
     50     virtual ~IptablesRestoreController();
     51 
     52 protected:
     53     friend class IptablesRestoreControllerTest;
     54     pid_t getIpRestorePid(const IptablesProcessType type);
     55 
     56     // The maximum number of times we poll(2) for a response on our set of polled
     57     // fds. Chosen so that the overall timeout is 5s. The timeout is so high because
     58     // our version of iptables still polls every second in xtables_lock.
     59     static int MAX_RETRIES;
     60 
     61     // The timeout (in millis) for each call to poll. The maximum wait is
     62     // |POLL_TIMEOUT_MS * MAX_RETRIES|. Chosen so that the overall timeout is 1s.
     63     static int POLL_TIMEOUT_MS;
     64 
     65 private:
     66     static IptablesProcess* forkAndExec(const IptablesProcessType type);
     67 
     68     int sendCommand(const IptablesProcessType type, const std::string& command,
     69                     std::string *output);
     70 
     71     static bool drainAndWaitForAck(const std::unique_ptr<IptablesProcess> &process,
     72                                    const std::string& command,
     73                                    std::string *output);
     74 
     75     static void maybeLogStderr(const std::unique_ptr<IptablesProcess> &process,
     76                                const std::string& command);
     77 
     78     // Guards calls to execute().
     79     std::mutex mLock;
     80 
     81     std::unique_ptr<IptablesProcess> mIpRestore;
     82     std::unique_ptr<IptablesProcess> mIp6Restore;
     83 };
     84 
     85 #endif  // NETD_SERVER_IPTABLES_RESTORE_CONTROLLER_H
     86