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/*
* QEMU Bridge Helper
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Richa Marwaha <rmarwah@linux.vnet.ibm.com>
* Corey Bryant <coreyb@linux.vnet.ibm.com>
*
* 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 <stdbool.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 void usage(void)
{
fprintf(stderr,
"Usage: qemu-bridge-helper [--use-vnet] --br=bridge --fd=unixfd\n");
}
static bool has_vnet_hdr(int fd)
{
unsigned int features = 0;
if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
return false;
}
if (!(features & IFF_VNET_HDR)) {
return false;
}
return true;
}
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 = -1;
int use_vnet = 0;
int mtu;
const char *bridge = NULL;
char iface[IFNAMSIZ];
int index;
int ret = EXIT_SUCCESS;
/* parse arguments */
for (index = 1; index < argc; index++) {
if (strcmp(argv[index], "--use-vnet") == 0) {
use_vnet = 1;
} else if (strncmp(argv[index], "--br=", 5) == 0) {
bridge = &argv[index][5];
} else if (strncmp(argv[index], "--fd=", 5) == 0) {
unixfd = atoi(&argv[index][5]);
} else {
usage();
return EXIT_FAILURE;
}
}
if (bridge == NULL || unixfd == -1) {
usage();
return EXIT_FAILURE;
}
/* 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: %s\n", strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* open the tap device */
fd = open("/dev/net/tun", O_RDWR);
if (fd == -1) {
fprintf(stderr, "failed to open /dev/net/tun: %s\n", strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* 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: %s\n", strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* 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': %s\n",
bridge, strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* 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: %s\n",
iface, mtu, strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* 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': %s\n",
iface, bridge, strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* bring the interface up */
prep_ifreq(&ifr, iface);
if (ioctl(ctlfd, SIOCGIFFLAGS, &ifr) == -1) {
fprintf(stderr, "failed to get interface flags for `%s': %s\n",
iface, strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
ifr.ifr_flags |= IFF_UP;
if (ioctl(ctlfd, SIOCSIFFLAGS, &ifr) == -1) {
fprintf(stderr, "failed to bring up interface `%s': %s\n",
iface, strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* write fd to the domain socket */
if (send_fd(unixfd, fd) == -1) {
fprintf(stderr, "failed to write fd to unix socket: %s\n",
strerror(errno));
ret = EXIT_FAILURE;
goto cleanup;
}
/* ... */
/* profit! */
cleanup:
return ret;
}
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