1 files changed, 84 insertions, 0 deletions
diff --git a/yocto/esp32d/tun.c b/yocto/esp32d/tun.c
new file mode 100644
index 0000000..75043a3
--- /dev/null
+++ b/yocto/esp32d/tun.c
@@ -0,0 +1,84 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+
+#include <linux/if.h>
+#include <linux/if_tun.h>
+
+#include <pthread.h>
+
+#include "spi.h"
+#include "tun.h"
+
+static pthread_t read_thd;
+
+static int tun_fd;
+static char tun_name[IFNAMSIZ];
+
+static int tun_alloc(char *dev, int flags) {
+    struct ifreq ifr;
+    int fd, err;
+    char *clonedev = "/dev/net/tun";
+
+    /* Arguments taken by the function:
+     *
+     * char *dev: the name of an interface (or '\0'). MUST have enough
+     *   space to hold the interface name if '\0' is passed
+     * int flags: interface flags (eg, IFF_TUN etc.)
+     */
+
+    fd = open(clonedev, O_RDWR);
+    if (fd < 0) {
+        return fd;
+    }
+
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = flags;  /* IFF_TUN or IFF_TAP, plus maybe IFF_NO_PI */
+
+    if (*dev) {
+        /* if a device name was specified, put it in the structure; otherwise,
+         * the kernel will try to allocate the "next" device of the
+         * specified type */
+        strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+    }
+
+    /* try to create the device */
+    err = ioctl(fd, TUNSETIFF, (void *) &ifr);
+    if (err < 0) {
+        close(fd);
+        return err;
+    }
+
+    /* if the operation was successful, write back the name of the
+     * interface to the variable "dev", so the caller can know
+     * it. Note that the caller MUST reserve space in *dev (see calling
+     * code below) */
+    strcpy(dev, ifr.ifr_name);
+
+    /* this is the special file descriptor that the caller will use to talk
+     * with the virtual interface */
+    return fd;
+}
+
+ssize_t tun_read(unsigned char *buffer, size_t buf_size) {
+    return read(tun_fd, buffer, buf_size);
+}
+
+ssize_t tun_write(unsigned char *buffer, size_t buf_len) {
+    return write(tun_fd, buffer, buf_len);
+}
+
+int tun_init(char *name) {
+    int rv;
+
+    if (strlen(name) >= sizeof(tun_name) - 1) return -1;
+    strcpy(tun_name, name);
+
+    tun_fd = tun_alloc(tun_name, IFF_TUN | IFF_NO_PI);
+    if (tun_fd < 0) return -1;
+
+    return 0;
+}