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__

void tun_close(tuntap_dev *device);

/* ********************************** */

#define N2N_OSX_TAPDEVICE_SIZE 32
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/macOS.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)
{
}

#endif /* __APPLE__ */