+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "config-host.h"
+
+#include<stdio.h>
+#include<errno.h>
+#include<fcntl.h>
+#include<unistd.h>
+#include<string.h>
+#include<stdlib.h>
+#include<ctype.h>
+
+#include<sys/types.h>
+#include<sys/ioctl.h>
+#include<sys/socket.h>
+#include<sys/un.h>
+#include<sys/prctl.h>
+
+#include<net/if.h>
+
+#include<linux/sockios.h>
+
+#include "net/tap-linux.h"
+
+static int has_vnet_hdr(int fd)
+{
+ unsigned int features = 0;
+ struct ifreq ifreq;
+
+ if (ioctl(fd, TUNGETFEATURES,&features) == -1) {
+ return -errno;
+ }
+
+ if (!(features& IFF_VNET_HDR)) {
+ return -ENOTSUP;
+ }
+
+ if (ioctl(fd, TUNGETIFF,&ifreq) != -1 || errno != EBADFD) {
+ return -ENOTSUP;
+ }
+
+ return 1;
+}
+
+static void prep_ifreq(struct ifreq *ifr, const char *ifname)
+{
+ memset(ifr, 0, sizeof(*ifr));
+ snprintf(ifr->ifr_name, IFNAMSIZ, "%s", ifname);
+}
+
+static int send_fd(int c, int fd)
+{
+ char msgbuf[CMSG_SPACE(sizeof(fd))];
+ struct msghdr msg = {
+ .msg_control = msgbuf,
+ .msg_controllen = sizeof(msgbuf),
+ };
+ struct cmsghdr *cmsg;
+ struct iovec iov;
+ char req[1] = { 0x00 };
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
+ msg.msg_controllen = cmsg->cmsg_len;
+
+ iov.iov_base = req;
+ iov.iov_len = sizeof(req);
+
+ msg.msg_iov =&iov;
+ msg.msg_iovlen = 1;
+ memcpy(CMSG_DATA(cmsg),&fd, sizeof(fd));
+
+ return sendmsg(c,&msg, 0);
+}
+
+int main(int argc, char **argv)
+{
+ struct ifreq ifr;
+ int fd, ctlfd, unixfd;
+ int use_vnet = 0;
+ int mtu;
+ const char *bridge;
+ char iface[IFNAMSIZ];
+ int index;
+
+ /* parse arguments */
+ if (argc< 3 || argc> 4) {
+ fprintf(stderr, "Usage: %s [--use-vnet] BRIDGE FD\n", argv[0]);
+ return 1;
+ }
+
+ index = 1;
+ if (strcmp(argv[index], "--use-vnet") == 0) {
+ use_vnet = 1;
+ index++;
+ if (argc == 3) {
+ fprintf(stderr, "invalid number of arguments\n");
+ return -1;
+ }
+ }
+
+ bridge = argv[index++];
+ unixfd = atoi(argv[index++]);
+
+ /* open a socket to use to control the network interfaces */
+ ctlfd = socket(AF_INET, SOCK_STREAM, 0);
+ if (ctlfd == -1) {
+ fprintf(stderr, "failed to open control socket\n");
+ return -errno;
+ }
+
+ /* open the tap device */
+ fd = open("/dev/net/tun", O_RDWR);
+ if (fd == -1) {
+ fprintf(stderr, "failed to open /dev/net/tun\n");
+ return -errno;
+ }
+
+ /* request a tap device, disable PI, and add vnet header support if
+ * requested and it's available. */
+ prep_ifreq(&ifr, "tap%d");
+ ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
+ if (use_vnet&& has_vnet_hdr(fd)) {
+ ifr.ifr_flags |= IFF_VNET_HDR;
+ }
+
+ if (ioctl(fd, TUNSETIFF,&ifr) == -1) {
+ fprintf(stderr, "failed to create tun device\n");
+ return -errno;
+ }
+
+ /* save tap device name */
+ snprintf(iface, sizeof(iface), "%s", ifr.ifr_name);
+
+ /* get the mtu of the bridge */
+ prep_ifreq(&ifr, bridge);
+ if (ioctl(ctlfd, SIOCGIFMTU,&ifr) == -1) {
+ fprintf(stderr, "failed to get mtu of bridge `%s'\n", bridge);
+ return -errno;
+ }
+
+ /* save mtu */
+ mtu = ifr.ifr_mtu;
+
+ /* set the mtu of the interface based on the bridge */
+ prep_ifreq(&ifr, iface);
+ ifr.ifr_mtu = mtu;
+ if (ioctl(ctlfd, SIOCSIFMTU,&ifr) == -1) {
+ fprintf(stderr, "failed to set mtu of device `%s' to %d\n",
+ iface, mtu);
+ return -errno;
+ }
+
+ /* add the interface to the bridge */
+ prep_ifreq(&ifr, bridge);
+ ifr.ifr_ifindex = if_nametoindex(iface);
+
+ if (ioctl(ctlfd, SIOCBRADDIF,&ifr) == -1) {
+ fprintf(stderr, "failed to add interface `%s' to bridge `%s'\n",
+ iface, bridge);
+ return -errno;
+ }
+
+ /* bring the interface up */
+ prep_ifreq(&ifr, iface);
+ if (ioctl(ctlfd, SIOCGIFFLAGS,&ifr) == -1) {
+ fprintf(stderr, "failed to get interface flags for `%s'\n", iface);
+ return -errno;
+ }
+
+ ifr.ifr_flags |= IFF_UP;
+ if (ioctl(ctlfd, SIOCSIFFLAGS,&ifr) == -1) {
+ fprintf(stderr, "failed to set bring up interface `%s'\n", iface);
+ return -errno;
+ }
+
+ /* write fd to the domain socket */
+ if (send_fd(unixfd, fd) == -1) {
+ fprintf(stderr, "failed to write fd to unix socket\n");
+ return -errno;
+ }
+
+ /* ... */
+
+ /* profit! */
