88 lines
1.7 KiB
C
88 lines
1.7 KiB
C
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#include <assert.h>
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#include <sys/ioctl.h>
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#include <net/if.h>
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#include <linux/if_tun.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdint.h>
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#define CLEAR(x) memset(&(x), 0x00, sizeof(x))
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#define IFNAME "tap0"
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#define BUFLEN 1600
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static int tun_alloc(char *dev)
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{
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struct ifreq ifr;
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int fd, err;
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if( (fd = open("/dev/net/tun", O_RDWR)) < 0 ) {
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perror("Cannot open TUN/TAP dev\n"
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"Make sure one exists with "
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"'$ mknod /dev/net/tun c 10 200'");
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exit(1);
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}
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CLEAR(ifr);
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/* Flags: IFF_TUN - TUN device (no Ethernet headers)
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* IFF_TAP - TAP device
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*
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* IFF_NO_PI - Do not provide packet information
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*/
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
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if( *dev ) {
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strncpy(ifr.ifr_name, dev, IFNAMSIZ);
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}
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if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
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perror("ERR: Could not ioctl tun");
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close(fd);
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return err;
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}
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strcpy(dev, ifr.ifr_name);
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return fd;
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}
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int main(int argc, char** argv) {
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char dev[IFNAMSIZ];
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int tun_fd;
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if (argc > 1) {
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assert(strlen(argv[1]) < IFNAMSIZ);
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strcpy(dev, argv[1]);
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} else {
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strcpy(dev, IFNAME);
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}
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printf("device name: %s\n", dev);
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tun_fd = tun_alloc(dev);
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int running = 1;
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uint8_t buf[BUFLEN];
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while (running) {
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int nread;
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if ((nread = read(tun_fd, buf, BUFLEN)) < 0) {
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perror("ERR: Read from tun_fd");
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break;
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}
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printf("Read %d bytes from device %s\n", nread, dev);
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}
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close(tun_fd);
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return EXIT_SUCCESS;
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}
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