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