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
26class IptablesProcess;
27
28class IptablesRestoreInterface {
29  public:
30    virtual ~IptablesRestoreInterface() = default;
31
32    // Execute |commands| on the given |target|, and populate |output| with stdout.
33    virtual int execute(const IptablesTarget target, const std::string& commands,
34                        std::string* output) = 0;
35};
36
37class IptablesRestoreController final : public IptablesRestoreInterface {
38  public:
39    // Not for general use. Use gCtls->iptablesRestoreCtrl
40    // to get an instance of this class.
41    IptablesRestoreController();
42
43    ~IptablesRestoreController() override;
44
45    int execute(const IptablesTarget target, const std::string& commands,
46                std::string* output) override;
47
48    enum IptablesProcessType {
49        IPTABLES_PROCESS,
50        IP6TABLES_PROCESS,
51        INVALID_PROCESS = -1,
52    };
53
54    // Called by the SIGCHLD signal handler when it detects that one
55    // of the forked iptables[6]-restore process has died.
56    IptablesProcessType notifyChildTermination(pid_t pid);
57
58protected:
59    friend class IptablesRestoreControllerTest;
60    pid_t getIpRestorePid(const IptablesProcessType type);
61
62    // The maximum number of times we poll(2) for a response on our set of polled
63    // fds. Chosen so that the overall timeout is 5s. The timeout is so high because
64    // our version of iptables still polls every second in xtables_lock.
65    static int MAX_RETRIES;
66
67    // The timeout (in millis) for each call to poll. The maximum wait is
68    // |POLL_TIMEOUT_MS * MAX_RETRIES|. Chosen so that the overall timeout is 1s.
69    static int POLL_TIMEOUT_MS;
70
71    void Init();
72
73private:
74    static IptablesProcess* forkAndExec(const IptablesProcessType type);
75
76    int sendCommand(const IptablesProcessType type, const std::string& command,
77                    std::string *output);
78
79    static bool drainAndWaitForAck(const std::unique_ptr<IptablesProcess> &process,
80                                   const std::string& command,
81                                   std::string *output);
82
83    static void maybeLogStderr(const std::unique_ptr<IptablesProcess> &process,
84                               const std::string& command);
85
86    // Guards calls to execute().
87    std::mutex mLock;
88
89    std::unique_ptr<IptablesProcess> mIpRestore;
90    std::unique_ptr<IptablesProcess> mIp6Restore;
91};
92
93#endif  // NETD_SERVER_IPTABLES_RESTORE_CONTROLLER_H
94