tapのサンプル

sample_tap.cpp

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>

#include <net/if.h>
/*
unsigned int if_nametoindex(const char *ifname);
char *if_indextoname(unsigned int ifindex, char *ifname);
*/

#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/if_arp.h>



#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>


#include <string>
#include <sstream>

static int _tap_num = 0;

class tap
{
    public:

    tap()
    {
        _init();
    };

    virtual ~tap()
    {
        //close(_tap_fd);
    };

    void set_mac(uint8_t *mac)
    {
        struct ifreq ifr;
        memset(&ifr, 0, sizeof(ifr));
        strncpy(ifr.ifr_name, ifname.c_str(), ifname.size());
        ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;

        memcpy(ifr.ifr_hwaddr.sa_data, mac, ETH_ALEN);

        int ret;
        ret = ioctl(_tap_fd, SIOCSIFHWADDR, (void*)&ifr);
        if(ret == -1) {
            perror("ioctl(SIOCSIFHWADDR)");
            exit(EXIT_FAILURE);
        }

        return;
    }

    void set_mtu(uint32_t size)
    {
        struct ifreq ifr;
        memset(&ifr, 0, sizeof(struct ifreq));
        strncpy(ifr.ifr_name, ifname.c_str(), ifname.size());

        ifr.ifr_mtu = size;

        int ret;
        ret = ioctl(_tap_fd, SIOCSIFMTU, (void *)&ifr);
        if(ret == -1) {
            perror("ioctl(SIOCSIFHWADDR)");
            exit(EXIT_FAILURE);
        }

        return;
    }

    void set_up()
    {
        struct ifreq ifr;
        memset(&ifr, 0, sizeof(struct ifreq));
        strncpy(ifr.ifr_name, ifname.c_str(), ifname.size());

        ifr.ifr_flags = IFF_UP;

        int ret;
        ret = ioctl(_tap_fd, SIOCSIFFLAGS, (void*)&ifr);
        if(ret == -1) {
            perror("ioctl(SIOCSIFFLAGS)");
            exit(EXIT_FAILURE);
        }

        return;
    }

    void set_down()
    {
        struct ifreq ifr;
        memset(&ifr, 0, sizeof(struct ifreq));
        strncpy(ifr.ifr_name, ifname.c_str(), ifname.size());

        ifr.ifr_flags = 0;

        int ret;
        ret = ioctl(_tap_fd, SIOCSIFFLAGS, (void*)&ifr);
        if(ret == -1) {
            perror("ioctl(SIOCSIFFLAGS)");
            exit(EXIT_FAILURE);
        }

        return;
    }


    private:

    int _tap_fd;
    std::string ifname;
    const std::string base_name = "ethnic";

    void _init()
    {
        ifname = base_name + str(_tap_num);
        _tap_num++;

        _tap_fd = open("/dev/net/tun", O_RDWR);
        if (_tap_fd == -1) {
            perror("open(/dev/net/tun)");
            exit(EXIT_FAILURE);
        }

        struct ifreq ifr;
        memset(&ifr, 0, sizeof(ifr));
        strncpy(ifr.ifr_name, ifname.c_str(), ifname.size());

        ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_MULTI_QUEUE;

        int ret;
        ret = ioctl(_tap_fd, TUNSETIFF, (void*)&ifr);
        if (ret == -1) {
            close(_tap_fd);
            perror("ioctl(TUNSETIFF)");
            exit(EXIT_FAILURE);
        }
        return;
    }

    template <typename T> std::string str(const T& t) {
        std::ostringstream os;
        os << t;
        return os.str();
    }

};

int main()
{
    class tap t;

    for (;;) {
        sleep(1);
    }
    return 0;
}