--- /dev/null
+#include <sys/un.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <errno.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+
+#include "tunalloc.h"
+
+#define OVS_SOCK "/var/run/pl-ovs.control"
+
+void send_fd(int p, int fd, char* vif_name);
+
+char *appname;
+
+#define ERROR(msg) \
+ do { \
+ fprintf(stderr, "%s: %s: %s", appname, msg, strerror(errno)); \
+ exit(1); \
+ } while (0)
+
+
+static
+int send_vif_fd(int sock_fd, int vif_fd, char *vif_name)
+{
+ int retval;
+ struct msghdr msg;
+ struct cmsghdr *p_cmsg;
+ struct iovec vec;
+ size_t cmsgbuf[CMSG_SPACE(sizeof(vif_fd)) / sizeof(size_t)];
+ int *p_fds;
+
+
+ msg.msg_control = cmsgbuf;
+ msg.msg_controllen = sizeof(cmsgbuf);
+ p_cmsg = CMSG_FIRSTHDR(&msg);
+ p_cmsg->cmsg_level = SOL_SOCKET;
+ p_cmsg->cmsg_type = SCM_RIGHTS;
+ p_cmsg->cmsg_len = CMSG_LEN(sizeof(vif_fd));
+ p_fds = (int *) CMSG_DATA(p_cmsg);
+ *p_fds = vif_fd;
+ msg.msg_controllen = p_cmsg->cmsg_len;
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_iov = &vec;
+ msg.msg_iovlen = 1;
+ msg.msg_flags = 0;
+
+ /* Send the interface name as the iov */
+ vec.iov_base = vif_name;
+ vec.iov_len = strlen(vif_name)+1;
+
+ while ((retval = sendmsg(sock_fd, &msg, 0)) == -1 && errno == EINTR);
+ if (retval == -1) {
+ ERROR("sending file descriptor");
+ }
+ return 0;
+}
+
+void send_fd(int p, int fd, char* vif_name)
+{
+ int control_fd;
+ int accept_fd;
+ struct sockaddr_un addr, accept_addr;
+ socklen_t addr_len = sizeof(accept_addr);
+
+ control_fd = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (control_fd == -1 && errno != ENOENT) {
+ ERROR("Could not create UNIX socket");
+ }
+
+ memset(&addr, 0, sizeof(struct sockaddr_un));
+ /* Clear structure */
+ addr.sun_family = AF_UNIX;
+ strncpy(addr.sun_path, OVS_SOCK,
+ sizeof(addr.sun_path) - 1);
+
+ if (unlink(OVS_SOCK) == -1 && errno != ENOENT) {
+ ERROR("Could not unlink " OVS_SOCK " control socket");
+ }
+
+ if (bind(control_fd, (struct sockaddr *) &addr,
+ sizeof(struct sockaddr_un)) == -1) {
+ ERROR("Could not bind to " OVS_SOCK " control socket");
+ }
+
+ if (listen(control_fd, 5) == -1) {
+ ERROR("listen on " OVS_SOCK " failed");
+ }
+ if (write(p, "1", 1) != 1) {
+ ERROR("writing on the synch pipe");
+ }
+ if ((accept_fd = accept(control_fd, (struct sockaddr*) &accept_addr,
+ &addr_len)) == -1) {
+ ERROR("accept on " OVS_SOCK " failed");
+ }
+ send_vif_fd(accept_fd, fd, vif_name);
+}
+
+int main(int argc, char* argv[])
+{
+ char if_name[IFNAMSIZ];
+ int p[2]; // synchronization pipe
+ char dummy;
+ int tun_fd;
+
+ (void) argc; // unused
+
+ if (pipe(p) < 0) {
+ ERROR("pipe");
+ }
+
+ tun_fd = tun_alloc(IFF_TAP, if_name);
+
+ appname = argv[0];
+
+ switch(fork()) {
+ case -1:
+ ERROR("fork");
+ exit(1);
+ case 0:
+ close(1);
+ open("/dev/null", O_WRONLY);
+ close(p[0]);
+ send_fd(p[1], tun_fd, if_name);
+ exit(0);
+ default:
+ close(p[1]);
+ if (read(p[0], &dummy, 1) != 1) {
+ ERROR("reading from the synch pipe");
+ }
+ printf("%s\n", if_name);
+ }
+ return 0;
+}