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/**
* (C) 2007-18 - 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 __linux__
/* *************************************************** */
static void read_mac(char *ifname, n2n_mac_t mac_addr) {
int _sock, res;
struct ifreq ifr;
macstr_t mac_addr_buf;
memset (&ifr,0,sizeof(struct ifreq));
/* Dummy socket, just to make ioctls with */
_sock=socket(PF_INET, SOCK_DGRAM, 0);
strcpy(ifr.ifr_name, ifname);
res = ioctl(_sock,SIOCGIFHWADDR,&ifr);
if(res < 0) {
perror ("Get hw addr");
traceEvent(TRACE_ERROR, "Unable to read interfce %s MAC", ifname);
} else
memcpy(mac_addr, ifr.ifr_ifru.ifru_hwaddr.sa_data, 6);
traceEvent(TRACE_NORMAL, "Interface %s has MAC %s",
ifname,
macaddr_str(mac_addr_buf, mac_addr ));
close(_sock);
}
/* ********************************** */
/** @brief Open and configure the TAP device for packet read/write.
*
* This routine creates the interface via the tuntap driver then uses ifconfig
* to configure address/mask and MTU.
*
* @param device - [inout] a device info holder object
* @param dev - user-defined name for the new iface,
* if NULL system will assign a name
* @param device_ip - address of iface
* @param device_mask - netmask for device_ip
* @param mtu - MTU for device_ip
*
* @return - negative value on error
* - non-negative file-descriptor on success
*/
int tuntap_open(tuntap_dev *device,
char *dev, /* user-definable interface name, eg. edge0 */
const char *address_mode, /* static or dhcp */
char *device_ip,
char *device_mask,
const char * device_mac,
int mtu) {
char *tuntap_device = "/dev/net/tun";
#define N2N_LINUX_SYSTEMCMD_SIZE 128
char buf[N2N_LINUX_SYSTEMCMD_SIZE];
struct ifreq ifr;
int rc;
device->fd = open(tuntap_device, O_RDWR);
if(device->fd < 0) {
traceEvent(TRACE_ERROR, "ioctl() [%s][%d]\n", strerror(errno), errno);
return -1;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP|IFF_NO_PI; /* Want a TAP device for layer 2 frames. */
strncpy(ifr.ifr_name, dev, IFNAMSIZ);
rc = ioctl(device->fd, TUNSETIFF, (void *)&ifr);
if(rc < 0) {
traceEvent(TRACE_ERROR, "ioctl() [%s][%d]\n", strerror(errno), rc);
close(device->fd);
return -1;
}
/* Store the device name for later reuse */
strncpy(device->dev_name, ifr.ifr_name, MIN(IFNAMSIZ, N2N_IFNAMSIZ) );
if ( device_mac && device_mac[0] != '\0' )
{
/* Set the hw address before bringing the if up. */
snprintf(buf, sizeof(buf), "/sbin/ifconfig %s hw ether %s",
ifr.ifr_name, device_mac );
system(buf);
traceEvent(TRACE_INFO, "Setting MAC: %s", buf);
}
if ( 0 == strncmp( "dhcp", address_mode, 5 ) )
{
snprintf(buf, sizeof(buf), "/sbin/ifconfig %s %s mtu %d up",
ifr.ifr_name, device_ip, mtu);
}
else
{
snprintf(buf, sizeof(buf), "/sbin/ifconfig %s %s netmask %s mtu %d up",
ifr.ifr_name, device_ip, device_mask, mtu);
}
system(buf);
traceEvent(TRACE_INFO, "Bringing up: %s", buf);
device->ip_addr = inet_addr(device_ip);
device->device_mask = inet_addr(device_mask);
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) {
FILE * fp=NULL;
ssize_t nread=0;
char buf[N2N_LINUX_SYSTEMCMD_SIZE];
/* Would rather have a more direct way to get the inet address but a netlink
* socket is overkill and probably less portable than ifconfig and sed. */
/* If the interface has no address (0.0.0.0) there will be no inet addr
* line and the returned string will be empty. */
snprintf( buf, sizeof(buf),
"/sbin/ifconfig %s | /bin/sed -e '/inet addr:/!d' -e 's/^.*inet addr://' -e 's/ .*$//'",
tuntap->dev_name);
fp = popen(buf, "r");
if (fp) {
memset(buf, 0, N2N_LINUX_SYSTEMCMD_SIZE); /* make sure buf is NULL terminated. */
nread = fread(buf, N2N_LINUX_SYSTEMCMD_SIZE-1, 1, fp);
fclose(fp);
fp = NULL;
traceEvent(TRACE_INFO, "ifconfig address = %s", buf);
if(nread > 0) {
buf[nread] = '\0';
tuntap->ip_addr = inet_addr(buf);
}
}
}
#endif /* #ifdef __linux__ */