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// $Id: tun.cc,v 1.2 2007-07-07 16:31:42 jl Exp $
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <libgen.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/if_tun.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <arpa/inet.h>
int mktun(const char *chan_name, unsigned char *ether_addr) {
struct ifreq ifr;
// struct ifreq ifw;
char if_name[IFNAMSIZ];
int fd, one = 1;
// int sd;
// construct TUN interface
if((fd = open("/dev/net/tun", O_RDWR)) == -1) {
perror("open");
return -1;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
snprintf(ifr.ifr_name, IFNAMSIZ, "%s", chan_name);
if(ioctl(fd, TUNSETIFF, (void *)&ifr) == -1) {
perror("TUNSETIFF");
close(fd);
return -1;
}
// save actual name
memcpy(if_name, ifr.ifr_name, IFNAMSIZ);
// get ether addr
memset(&ifr, 0, sizeof(ifr));
memcpy(ifr.ifr_name, if_name, IFNAMSIZ);
if(ioctl(fd, SIOCGIFHWADDR, (void *)&ifr) == -1) {
perror("SIOCGIFHWADDR");
close(fd);
return -1;
}
memcpy(ether_addr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
// set persistent
if(ioctl(fd, TUNSETPERSIST, (void *)&one) == -1) {
perror("TUNSETPERSIST");
close(fd);
return -1;
}
// set interface up
/* XXX must be root
if((sd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
perror("socket");
close(fd);
return -1;
}
// get current flags
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, if_name, IFNAMSIZ - 1);
if(ioctl(sd, SIOCGIFFLAGS, &ifr) == -1) {
perror("SIOCGIFFLAGS");
close(sd);
close(fd);
return -1;
}
// set up
memset(&ifw, 0, sizeof(ifw));
strncpy(ifw.ifr_name, if_name, IFNAMSIZ - 1);
ifw.ifr_flags = ifr.ifr_flags | IFF_UP | IFF_RUNNING;
if(ioctl(sd, SIOCSIFFLAGS, &ifw) == -1) {
perror("SIOCSIFFLAGS");
close(sd);
close(fd);
return -1;
}
close(sd);
*/
return fd;
}
static inline int min(int a, int b) {
return (a < b)? a : b;
}
static const unsigned int DEFAULT_MTU = 1500;
static const unsigned short ether_type = 0xfed5; // current dtap ethertype
int write_interface(int fd, unsigned char *data, unsigned int data_len,
unsigned char *ether_addr) {
unsigned char frame[DEFAULT_MTU]; // XXX buffer overflow?
struct ethhdr eh;
if(fd < 0)
return data_len;
memcpy(eh.h_dest, ether_addr, ETH_ALEN);
memcpy(eh.h_source, ether_addr, ETH_ALEN);
eh.h_proto = htons(ether_type);
memcpy(frame, &eh, sizeof(eh));
memcpy(frame + sizeof(eh), data,
min(data_len, sizeof(frame) - sizeof(eh)));
if(write(fd, frame, sizeof(eh) + data_len) == -1) {
perror("write");
return -1;
}
return data_len;
}
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