59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
#include <errno.h>
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#include <fcntl.h>
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#include <linux/if.h>
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#include <linux/if_tun.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <unistd.h>
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#define DEVICE_NODE_TUN /dev/net/tun
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#define BUFFER_SIZE 0x1000
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#define EXIT_SUCCESS 0
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#define EXIT_USAGE 1
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#define EXIT_RUNTIME 2
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int file_descriptor;
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char buffer[BUFFER_SIZE];
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struct ifreq ifr;
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int main(int argc, char** argv) {
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if (argc != 2) {
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fprintf(stderr, "Usage: %s TAP\n", argv[0]);
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return EXIT_USAGE;
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} else if ((strlen(argv[1])==2 && strncmp(argv[1], "-h", 2)==0) || (strlen(argv[1])==6 &&strncmp(argv[1], "--help", 6))) {
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fprintf(stdout, "Usage: %s TAP\n", argv[0]);
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return EXIT_SUCCESS;
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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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strncpy(ifr.ifr_name, argv[1], IFNAMSIZ);
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file_descriptor = open("/dev/net/tun", O_RDWR);
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if (file_descriptor == -1) {
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fprintf(stderr, "An error occurred while trying to open DEVICE_NODE_TUN: %i\n", errno);
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return EXIT_RUNTIME;
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}
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if (ioctl(file_descriptor, TUNSETIFF, &ifr) == -1) {
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fprintf(stderr, "An error occurred while trying to ioctl: %i\n", errno);
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close(file_descriptor);
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return EXIT_RUNTIME;
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}
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//TODO:
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// while input not EOF
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// and the tap is still a valid device (it might go away)
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// read from tap to stdout
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// read from stdin to tap
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//TODO: signal handler for SIGINT (and SIGHUP? maybe others?)
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if (fcntl(fd, F_GETFD) != -1 || errno != EBADF) {
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close(file_descriptor);
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}
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return EXIT_SUCCESS;
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}
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