diff options
Diffstat (limited to 'qemu-bridge-helper.c')
| -rw-r--r-- | qemu-bridge-helper.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c new file mode 100644 index 0000000000..48c5e22ea0 --- /dev/null +++ b/qemu-bridge-helper.c @@ -0,0 +1,221 @@ +/* + * 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; +} |