ext/god/netlink_handler.c

   1 #ifdef __linux__ /* only build on linux */
   2
   3 #include <ruby.h>
   4 #include <sys/types.h>
   5 #include <sys/socket.h>
   6 #include <linux/netlink.h>
   7 #include <linux/connector.h>
   8 #include <linux/cn_proc.h>
   9 #include <errno.h>
  10
  11 static VALUE cNetlinkHandler;
  12 static VALUE cEventHandler;
  13 static VALUE mGod;
  14
  15 static ID proc_exit;
  16 static ID proc_fork;
  17 static ID m_call;
  18 static ID m_watching_pid;
  19
  20 static int nl_sock;   /* socket for netlink connection  */
  21
  22
  23 VALUE
  24 nlh_handle_events()
  25 {
  26   char buff[CONNECTOR_MAX_MSG_SIZE];
  27   struct nlmsghdr *hdr;
  28   struct proc_event *event;
  29
  30   fd_set fds;
  31
  32   FD_ZERO(&fds);
  33   FD_SET(nl_sock, &fds);
  34
  35   if (0 > select(nl_sock + 1, &fds, NULL, NULL, NULL)) {
  36     rb_raise(rb_eStandardError, strerror(errno));
  37   }
  38
  39   /* If there were no events detected, return */
  40   if (! FD_ISSET(nl_sock, &fds)) {
  41     return INT2FIX(0);
  42   }
  43
  44   /* if there are events, make calls */
  45   if (-1 == recv(nl_sock, buff, sizeof(buff), 0)) {
  46     rb_raise(rb_eStandardError, strerror(errno));
  47   }
  48
  49   hdr = (struct nlmsghdr *)buff;
  50
  51   if (NLMSG_ERROR == hdr->nlmsg_type) {
  52     rb_raise(rb_eStandardError, strerror(errno));
  53   } else if (NLMSG_DONE == hdr->nlmsg_type) {
  54
  55     event = (struct proc_event *)((struct cn_msg *)NLMSG_DATA(hdr))->data;
  56
  57     switch(event->what) {
  58       case PROC_EVENT_EXIT:
  59         if (Qnil == rb_funcall(cEventHandler, m_watching_pid, 1, INT2FIX(event->event_data.exit.process_pid))) {
  60           return INT2FIX(0);
  61         }
  62
  63         rb_funcall(cEventHandler, m_call, 2, INT2FIX(event->event_data.exit.process_pid), ID2SYM(proc_exit));
  64         return INT2FIX(1);
  65
  66       /* TODO: On fork, call and pass pid of child */
  67       case PROC_EVENT_FORK:
  68         if (Qnil == rb_funcall(cEventHandler, m_watching_pid, 1, INT2FIX(event->event_data.fork.parent_pid))) {
  69           return INT2FIX(0);
  70         }
  71
  72         rb_funcall(cEventHandler, m_call, 2, INT2FIX(event->event_data.fork.parent_pid), ID2SYM(proc_fork));
  73         return INT2FIX(1);
  74     }
  75   }
  76
  77   return Qnil;
  78 }
  79
  80
  81 #define NL_MESSAGE_SIZE (sizeof(struct nlmsghdr) + sizeof(struct cn_msg) + \
  82                          sizeof(int))
  83
  84 void
  85 connect_to_netlink()
  86 {
  87   struct sockaddr_nl sa_nl; /* netlink interface info */
  88   char buff[NL_MESSAGE_SIZE];
  89   struct nlmsghdr *hdr; /* for telling netlink what we want */
  90   struct cn_msg *msg;   /* the actual connector message
  91
  92   /* connect to netlink socket */
  93   nl_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
  94
  95   bzero(sa_nl, sizeof(sa_nl));
  96   sa_nl.nl_family = AF_NETLINK;
  97   sa_nl.nl_groups = CN_IDX_PROC;
  98   sa_nl.nl_pid    = getpid();
  99
 100   bind(nl_sock, (struct sockaddr *)&sa_nl, sizeof(sa_nl));
 101
 102   /* Fill header */
 103   hdr = (struct nlmsghdr *)buff;
 104   hdr->nlmsg_len = NL_MESSAGE_SIZE;
 105   hdr->nlmsg_type = NLMSG_DONE;
 106   hdr->nlmsg_flags = 0;
 107   hdr->nlmsg_seq = 0;
 108   hdr->nlmsg_pid = getpid();
 109
 110   /* Fill message */
 111   msg = (struct cn_msg *)NLMSG_DATA(hdr);
 112   msg->id.idx = CN_IDX_PROC;  /* Connecting to process information */
 113   msg->id.val = CN_VAL_PROC;
 114   msg->seq = 0;
 115   msg->ack = 0;
 116   msg->len = sizeof(int);
 117   msg->data[0] = PROC_CN_MCAST_LISTEN;
 118
 119   if (-1 == send(nl_sock, hdr, hdr->nlmsg_len, 0)) {
 120     rb_raise(rb_eStandardError, strerror(errno));
 121   }
 122 }
 123
 124 void
 125 Init_netlink_handler_ext()
 126 {
 127   proc_exit = rb_intern("proc_exit");
 128   proc_fork = rb_intern("proc_fork");
 129   m_call = rb_intern("call");
 130   m_watching_pid = rb_intern("watching_pid?");
 131
 132   mGod = rb_const_get(rb_cObject, rb_intern("God"));
 133   cEventHandler = rb_const_get(mGod, rb_intern("EventHandler"));
 134   cNetlinkHandler = rb_define_class_under(mGod, "NetlinkHandler", rb_cObject);
 135   rb_define_singleton_method(cNetlinkHandler, "handle_events", nlh_handle_events, 0);
 136
 137   connect_to_netlink();
 138 }
 139
 140 #endif