congestvpn/TunDevice.hpp

#pragma once

#include <string>
#include <poll.h>
#include "util.hpp"

class TunDevice {
    public:
        class InitializationError : public MsgException {
            public:
                InitializationError(
                        const std::string& msg,
                        int code=0,
                        bool is_perror=false)
                    : MsgException(msg, code, is_perror) {}
        };
        class NetError : public MsgException {
            public:
                NetError(
                        const std::string& msg,
                        int code=0,
                        bool is_perror=false)
                    : MsgException(msg, code, is_perror) {}
        };

        TunDevice(const std::string& dev);
        ~TunDevice();

        const std::string& get_dev_name() const { return _dev_name; }
        int get_fd() const { return _fd; }

        /** Get the interface's MTU */
        uint16_t get_mtu() const;

        /** Set the interface's MTU */
        bool set_mtu(uint16_t mtu);

        /* Reads a packet from the device.
         * Timeouts after `timeout` ms, or never if `timeout < 0`.
         * Upon timeout, returns 0.
         */
        size_t poll_packet(char* read_buffer, size_t buf_size, int timeout=-1);

        /* Reads a packet, blocking if none is available. */
        size_t read(char* read_buffer, size_t buf_size);

        size_t write(const char* data, size_t len);

    private:
        int _fd;
        std::string _dev_name;
        struct pollfd _poll_fd;
        size_t _last_read_size;
};