Skip to content

Commit

Permalink
Remove calls to system() in tuntap_linux
Browse files Browse the repository at this point in the history 
Fixes #177
  • Loading branch information
@emanuele-f
emanuele-f committed Sep 17, 2019
1 parent 49f1f1b commit 5d2d19a
Showing 1 changed file with 90 additions and 51 deletions.
141 changes: 90 additions & 51 deletions tuntap_linux.c
View file
Expand Up @@ -20,6 +20,8 @@

#ifdef __linux__

#include <net/if_arp.h>

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

static void read_mac(char *ifname, n2n_mac_t mac_addr) {
Expand Down Expand Up @@ -48,10 +50,70 @@ static void read_mac(char *ifname, n2n_mac_t mac_addr) {

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

static int setup_ifname(int fd, const char *ifname, const char *ipaddr,
const char *netmask, const char *mac, int mtu) {
struct ifreq ifr;

strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
ifr.ifr_name[IFNAMSIZ-1] = '\0';

if(mac && mac[0]) {
str2mac((uint8_t *)ifr.ifr_hwaddr.sa_data, mac);
ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;

if(ioctl(fd, SIOCSIFHWADDR, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCSIFHWADDR) failed [%d]: %s", errno, strerror(errno));
return(-1);
}
}

ifr.ifr_addr.sa_family = AF_INET;

/* Interface Address */
inet_pton(AF_INET, ipaddr, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
if(ioctl(fd, SIOCSIFADDR, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCSIFADDR) failed [%d]: %s", errno, strerror(errno));
return(-2);
}

/* Netmask */
if(netmask && (((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr.s_addr != 0)) {
inet_pton(AF_INET, netmask, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
if(ioctl(fd, SIOCSIFNETMASK, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCSIFNETMASK, %s) failed [%d]: %s", netmask, errno, strerror(errno));
return(-3);
}
}

/* MTU */
ifr.ifr_mtu = mtu;
if(ioctl(fd, SIOCSIFMTU, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCSIFMTU) failed [%d]: %s", errno, strerror(errno));
return(-4);
}

/* Set up and running */
if(ioctl(fd, SIOCGIFFLAGS, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCGIFFLAGS) failed [%d]: %s", errno, strerror(errno));
return(-5);
}

ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);

if(ioctl(fd, SIOCSIFFLAGS, &ifr) == -1) {
traceEvent(TRACE_ERROR, "ioctl(SIOCSIFFLAGS) failed [%d]: %s", errno, strerror(errno));
return(-6);
}

return(0);
}

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

/** @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.
* This routine creates the interface via the tuntap driver and then
* configures it.
*
* @param device - [inout] a device info holder object
* @param dev - user-defined name for the new iface,
Expand All @@ -71,8 +133,7 @@ int tuntap_open(tuntap_dev *device,
const char * device_mac,
int mtu) {
char *tuntap_device = "/dev/net/tun";
#define N2N_LINUX_SYSTEMCMD_SIZE 128
char buf[N2N_LINUX_SYSTEMCMD_SIZE];
int ioctl_fd;
struct ifreq ifr;
int rc;

Expand All @@ -97,28 +158,18 @@ int tuntap_open(tuntap_dev *device,
/* 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((ioctl_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
return -1;
}

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);
}
if(setup_ifname(ioctl_fd, device->dev_name, device_ip, device_mask, device_mac, mtu) < 0) {
close(ioctl_fd);
close(device->fd);
return -1;
}

system(buf);
traceEvent(TRACE_INFO, "Bringing up: %s", buf);
close(ioctl_fd);

device->ip_addr = inet_addr(device_ip);
device->device_mask = inet_addr(device_mask);
Expand Down Expand Up @@ -149,34 +200,22 @@ void tuntap_close(struct tuntap_dev *tuntap) {
/* 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);
}
struct ifreq ifr;
int fd;

if((fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
return;
}
}

ifr.ifr_addr.sa_family = AF_INET;
strncpy(ifr.ifr_name, tuntap->dev_name, IFNAMSIZ);
ifr.ifr_name[IFNAMSIZ-1] = '\0';

if(ioctl(fd, SIOCGIFADDR, &ifr) != -1)
tuntap->ip_addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;

close(fd);
}

#endif /* #ifdef __linux__ */

0 comments on commit 5d2d19a

Please sign in to comment.