n2n/src/tuntap_osx.c

/**
 * (C) 2007-20 - ntop.org and contributors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not see see <http://www.gnu.org/licenses/>
 *
 */


#include "n2n.h"


#ifdef __APPLE__


#define N2N_OSX_TAPDEVICE_SIZE 32


void tun_close (tuntap_dev *device);


int tuntap_open (tuntap_dev *device /* ignored */,
                 char *dev,
                 const char *address_mode, /* static or dhcp */
                 char *device_ip,
                 char *device_mask,
                 const char * device_mac,
                 int mtu) {

    int i;
    char tap_device[N2N_OSX_TAPDEVICE_SIZE];

    for(i = 0; i < 255; i++) {
        snprintf(tap_device, sizeof(tap_device), "/dev/tap%d", i);

        device->fd = open(tap_device, O_RDWR);
        if(device->fd > 0) {
            traceEvent(TRACE_NORMAL, "Succesfully open %s", tap_device);
            break;
        }
    }

    if(device->fd < 0) {
        traceEvent(TRACE_ERROR, "Unable to open any tap devices /dev/tap0 through /dev/tap254. Is this user properly authorized to access those descriptors?");
        traceEvent(TRACE_ERROR, "Please read https://github.com/ntop/n2n/blob/dev/doc/Building.md");
        return -1;
    } else {
        char buf[256];
        FILE *fd;

        device->ip_addr = inet_addr(device_ip);

        if(device_mac && device_mac[0] != '\0') {
            // FIXME - this is not tested. might be wrong syntax for OS X
            // set the hw address before bringing the if up
            snprintf(buf, sizeof(buf), "ifconfig tap%d ether %s", i, device_mac);
            system(buf);
        }

        snprintf(buf, sizeof(buf), "ifconfig tap%d %s netmask %s mtu %d up", i, device_ip, device_mask, mtu);
        system(buf);

        traceEvent(TRACE_NORMAL, "Interface tap%d up and running (%s/%s)", i, device_ip, device_mask);

        // read MAC address
        snprintf(buf, sizeof(buf), "ifconfig tap%d |grep ether|cut -c 8-24", i);
        // traceEvent(TRACE_INFO, "%s", buf);

        fd = popen(buf, "r");
        if(fd < 0) {
            tuntap_close(device);
            return -1;
        } else {
            int a, b, c, d, e, f;

            buf[0] = 0;
            fgets(buf, sizeof(buf), fd);
            pclose(fd);

            if(buf[0] == '\0') {
                traceEvent(TRACE_ERROR, "Unable to read tap%d interface MAC address");
                exit(0);
            }

            traceEvent(TRACE_NORMAL, "Interface tap%d [MTU %d] mac %s", i, mtu, buf);
            if(sscanf(buf, "%02x:%02x:%02x:%02x:%02x:%02x", &a, &b, &c, &d, &e, &f) == 6) {
                device->mac_addr[0] = a, device->mac_addr[1] = b;
                device->mac_addr[2] = c, device->mac_addr[3] = d;
                device->mac_addr[4] = e, device->mac_addr[5] = f;
            }
        }
    }

    // read_mac(dev, device->mac_addr);

    return(device->fd);
}


int tuntap_read (struct tuntap_dev *tuntap, unsigned char *buf, int len) {

    return(read(tuntap->fd, buf, len));
}


int tuntap_write (struct tuntap_dev *tuntap, unsigned char *buf, int len) {

    return(write(tuntap->fd, buf, len));
}


void tuntap_close (struct tuntap_dev *tuntap) {

    close(tuntap->fd);
}

// fill out the ip_addr value from the interface, called to pick up dynamic address changes
void tuntap_get_address (struct tuntap_dev *tuntap) {

    // no action
}


#endif /* __APPLE__ */