I've implemented a prototype kernel module as described in this email: http://lists.gnu.org/archive/html/qemu-devel/2005-08/msg00123.html Full source code and makefile attached as a bz2ball.
Not really strictly related to VDE, this module basically enables the creation of a user space bridge. Basically it creates /proc/vdeinject and uses that file to expose the netif_rx() function. When you write a packet to it, the module handles all the skb stuff and attempts to inject the packet into eth0. Currently my VDE setup seems to be broken (my vde_pcap and vde_packet in particular don't want to work with my vde_switch). It appears to work tho (as when using vde_pcap_inject to connect to tap0, a dhcpd server that I was running on tap0 was able to pick up dhcp requests from a guest). Also, for those who want to see live updates as soon as I make changes, here is a link: http://jma-box.student.umd.edu:8080/vde-inject/vdeinject.c -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection.
vde-inject.tbz
Description: Binary data
/* Copyright (C) 2005 Jim Brown
* Copyright (C) 2005 Henrik Nordstrom
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
*
* The VDE connection setup (open_vde) is loosely based on a similar
* functions in vdeq.c by Renzo Davoli
*/
#include <sys/socket.h>
#include <netpacket/packet.h>
#include <net/ethernet.h> /* the L2 protocols */
#include <sys/ioctl.h>
#include <fcntl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <sys/un.h>
#include <errno.h>
#include <signal.h>
#include <linux/if_tun.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <pcap.h>
#define SWITCH_MAGIC 0xfeedface
#define BUFSIZE 2048
#define ETH_ALEN 6
#define PCAP_READ_TIMEOUT 1
enum request_type {
REQ_NEW_CONTROL
};
struct request_v3 {
uint32_t magic;
uint32_t version;
enum request_type type;
struct sockaddr_un sock;
};
static int
open_vde(char *name, int intno, int group)
{
int pid = getpid();
struct request_v3 req;
int fdctl;
int fddata;
struct sockaddr_un sock;
if ((fdctl = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
perror("socket");
exit(1);
}
sock.sun_family = AF_UNIX;
snprintf(sock.sun_path, sizeof(sock.sun_path), "%s", name);
if (connect(fdctl, (struct sockaddr *) &sock, sizeof(sock))) {
perror("connect");
exit(1);
}
memset(&req, 0, sizeof(req));
req.magic = SWITCH_MAGIC;
req.version = 3;
req.type = REQ_NEW_CONTROL + ((group > 0) ? ((geteuid() << 8) + group) << 8
: 0);
req.sock.sun_family = AF_UNIX;
sprintf(&req.sock.sun_path[1], "%5d-%2d", pid, intno);
if ((fddata = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0) {
perror("socket");
exit(1);
}
if (bind(fddata, (struct sockaddr *) &req.sock, sizeof(req.sock)) < 0) {
perror("bind");
exit(1);
}
if (send(fdctl, &req, sizeof(req), 0) < 0) {
perror("send");
exit(1);
}
if (recv(fdctl, &sock, sizeof(struct sockaddr_un), 0) < 0) {
perror("recv");
exit(1);
}
if (connect(fddata, (struct sockaddr *) &sock, sizeof(struct sockaddr_un))
< 0) {
perror("connect");
exit(1);
}
/* note: fdctl is intentionally leaked. Closed on exit by the OS. */
return fddata;
}
void
set_nonblocking(int fd)
{
int fl = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, (fl | O_NONBLOCK));
}
void
pcap_relay(u_char *args, const struct pcap_pkthdr *header, const u_char *
packet)
{
int * vde_socket = (int *)args;
send(*vde_socket, packet, header->len, 0);
}
static void
wrap_dispatch(fd_set * rfd, pcap_t * handle, int vde_socket)
{
int n;
if (FD_ISSET(pcap_get_selectable_fd(handle), rfd)) {
n = pcap_dispatch(handle, -1, pcap_relay, (u_char *)&vde_socket);
}
}
int pcap_sendpacket(pcap_t * handle, const u_char * packet, int len, const char
* dev)
{
struct sockaddr_ll sa1;
struct ifreq ifr;
strncpy (ifr.ifr_name, dev, sizeof(ifr.ifr_name) - 1);
ifr.ifr_name[sizeof(ifr.ifr_name)-1] = '\0';
if (ioctl(pcap_fileno(handle), SIOCGIFINDEX, &ifr) == -1)
return -1;
memset(&sa1, 0, sizeof (sa1));
sa1.sll_family = AF_PACKET;
sa1.sll_ifindex = ifr.ifr_ifindex;
sa1.sll_protocol = htons(ETH_P_ALL);
if (sendto(pcap_fileno(handle), packet, len, 0, (struct sockaddr *)&sa1,
sizeof(sa1)) == len)
{
return 0;
}
else
{
return -1;
}
}
int vde_inject_fd = -1;
static void
relay(fd_set * rfd, int vde_socket, pcap_t * handle, const char * dev)
{
int n;
char packet[65536];
union {
struct sockaddr_ll ll;
struct sockaddr_un un;
} sa;
socklen_t sa_len = sizeof(sa);
if (FD_ISSET(vde_socket, rfd)) {
n = recvfrom(vde_socket, packet, sizeof(packet), 0, (struct sockaddr
*)&sa, &sa_len);
if (n > 0)
{
pcap_sendpacket(handle, packet, n, dev);
vde_inject_fd = open("/proc/vdeinject", O_WRONLY);
if (vde_inject_fd != -1)
{
write(vde_inject_fd, packet, n);
close(vde_inject_fd);
}
}
else if (n == 0)
exit(1);
else if (errno != EINTR) {
perror("recv:");
exit(1);
}
}
}
pcap_t * a;
void handle_cl(int signal)
{
printf("Caught signal %d, cleaning up ...\n", signal);
pcap_close(a);
exit(0);
}
int
main(int argc, char **argv)
{
int vde_socket;
pcap_t * handle;
char errbuf[PCAP_ERRBUF_SIZE];
const u_char * packet;
fd_set rfd;
int fds;
if (argc != 3) {
printf("Usage: %s interface vde_socket\n", argv[0]);
exit(1);
}
handle = pcap_open_live(argv[1], BUFSIZ, 1, PCAP_READ_TIMEOUT, errbuf);
if (handle == NULL)
{
printf("%s\n", errbuf);
exit(1);
}
vde_socket = open_vde(argv[2], 0, 0);
set_nonblocking(vde_socket);
a = handle;
signal(SIGINT, handle_cl);
fds = pcap_get_selectable_fd(handle);
if (vde_socket > fds)
fds = vde_socket;
fds += 1;
FD_ZERO(&rfd);
int i;
for (;;) {
int n;
FD_SET(pcap_get_selectable_fd(handle), &rfd);
FD_SET(vde_socket, &rfd);
n = select(fds, &rfd, NULL, NULL, NULL);
if (n > 0) {
wrap_dispatch(&rfd, handle, vde_socket);
relay(&rfd, vde_socket, handle, argv[1]);
} else if (n < 0 && errno != EINTR) {
perror("select:");
}
}
}
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