a first simple test-program for the vpn-functionality

diff --git a/src/vpn/tun.c b/src/vpn/tun.c
new file mode 100644 (file)
index 0000000..6e184b0
--- /dev/null
+++ b/src/vpn/tun.c
@@ -0,0 +1,104 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+
+#include <linux/if.h>
+#include <linux/if_tun.h>
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+int tun_alloc(char *dev) {
+       struct ifreq ifr;
+       int fd, err;
+
+       if( (fd = open("/dev/net/tun", O_RDWR)) < 0 ) {
+               fprintf(stderr, "open: %s\n", strerror(errno));
+               return -1;
+       }
+
+       memset(&ifr, 0, sizeof(ifr));
+
+       ifr.ifr_flags = IFF_TUN; 
+       if(*dev)
+               strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+
+       if ((err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
+               close(fd);
+               fprintf(stderr, "ioctl: %s\n", strerror(errno));
+               return err;
+       }
+       strcpy(dev, ifr.ifr_name);
+       return fd;
+}
+
+void n2o(fd) {
+       char buf[1024];
+       int r, w;
+       for(;;) {
+               r = read(fd, buf, 1024);
+               if (r < 0) {
+                       fprintf(stderr, "n2o read: %s\n", strerror(errno));
+                       exit(1);
+               }
+               if (r == 0) {
+                       close(fd);
+                       exit(0);
+               }
+               while (r > 0) {
+                       w = write(1, buf, r);
+                       if (w < 0) {
+                               fprintf(stderr, "n2o write: %s\n", strerror(errno));
+                               close(fd);
+                               exit(1);
+                       }
+                       r -= w;
+               }
+       }
+}
+
+void o2n(fd) {
+       char buf[1024];
+       int r, w;
+       for(;;) {
+               r = read(0, buf, 1024);
+               if (r < 0) {
+                       fprintf(stderr, "o2n read: %s\n", strerror(errno));
+                       exit(1);
+               }
+               if (r == 0) {
+                       close(fd);
+                       exit(0);
+               }
+               while (r > 0) {
+                       w = write(fd, buf, r);
+                       if (w < 0) {
+                               fprintf(stderr, "o2n write: %s\n", strerror(errno));
+                               close(fd);
+                               exit(1);
+                       }
+                       r -= w;
+               }
+       }
+}
+
+int main(int argc, char** argv) {
+       char name[IFNAMSIZ];
+       int fd;
+
+       memset(name, 0, IFNAMSIZ);
+
+       strncpy(name, "mynet", IFNAMSIZ);
+       fprintf(stderr, "fd = %d, name = %s\n", fd = tun_alloc(name), name);
+
+       if (fork() == 0)
+               n2o(fd);
+
+       o2n(fd);
+
+       return 0;
+}