Used to detect if the netlink linux interface works properly

netlink_test.c

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/connector.h>
#define _LINUX_TIME_H
#include <linux/cn_proc.h>
#include <errno.h>

static int nl_sock;

#define NL_MESSAGE_SIZE (sizeof(struct nlmsghdr) + sizeof(struct cn_msg) + \
                         sizeof(int))

int main(void) {
  struct sockaddr_nl sa_nl; /* netlink interface info */
  char buff[NL_MESSAGE_SIZE];
  struct nlmsghdr *hdr; /* for telling netlink what we want */
  struct cn_msg *msg;   /* the actual connector message */

  nl_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
  if (-1 == nl_sock) {
    perror("socket()");
    return 1;
  }
  printf("first phase good, fire ! !\n");

  bzero(&sa_nl, sizeof(sa_nl));
  sa_nl.nl_family = AF_NETLINK;
  sa_nl.nl_groups = CN_IDX_PROC;
  sa_nl.nl_pid    = getpid();

  if (-1 == bind(nl_sock, (struct sockaddr *)&sa_nl, sizeof(sa_nl))) {
    perror("bind()");
    return 1;
  }

  printf("take off successful\n");

  /* Fill header */
  hdr = (struct nlmsghdr *)buff;
  hdr->nlmsg_len = NL_MESSAGE_SIZE;
  hdr->nlmsg_type = NLMSG_DONE;
  hdr->nlmsg_flags = 0;
  hdr->nlmsg_seq = 0;
  hdr->nlmsg_pid = getpid();

  /* Fill message */
  msg = (struct cn_msg *)NLMSG_DATA(hdr);
  msg->id.idx = CN_IDX_PROC;  /* Connecting to process information */
  msg->id.val = CN_VAL_PROC;
  msg->seq = 0;
  msg->ack = 0;
  msg->flags = 0;

  msg->flags = 0;
  msg->len = sizeof(int);
  *(int*)msg->data = PROC_CN_MCAST_LISTEN;

  if (-1 == send(nl_sock, hdr, hdr->nlmsg_len, 0)) {
    perror("send()");
    return 1;
  }

  printf("back to base\n");
  return 0;
}

Used to debug issues with God on Linux+LXC.

I [2014-05-22 13:35:32]  INFO: Loading /var/pets/installed/godlike/current/god.default.rb
I [2014-05-22 13:35:32]  INFO: Syslog enabled.
I [2014-05-22 13:35:32]  INFO: Using pid file directory: /var/run/god
Using DIR /var/pets/installed/pusher-global/current
E [2014-05-22 13:35:32] ERROR: Condition 'God::Conditions::ProcessExits' requires an event system but none has been loaded