a first simple test-program for the vpn-functionality

1 files changed, 104 insertions, 0 deletions

diff --git a/src/vpn/tun.c b/src/vpn/tun.c
new file mode 100644
index 000000000..6e184b079
--- /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;
+}