+/* Returns zero on success, less than zero on socket error and greater than
+ * zero on other errors. */
+static int conn_read_netlink (void)
+{
+ int fd;
+ struct sockaddr_nl nladdr;
+ struct nlreq req;
+ struct msghdr msg;
+ struct iovec iov;
+ struct inet_diag_msg *r;
+ char buf[8192];
+
+ /* If this fails, it's likely a permission problem. We'll fall back to
+ * reading this information from files below. */
+ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_INET_DIAG);
+ if (fd < 0)
+ {
+ ERROR ("tcpconns plugin: conn_read_netlink: socket(AF_NETLINK, SOCK_RAW, "
+ "NETLINK_INET_DIAG) failed: %s",
+ sstrerror (errno, buf, sizeof (buf)));
+ return (-1);
+ }
+
+ memset(&nladdr, 0, sizeof(nladdr));
+ nladdr.nl_family = AF_NETLINK;
+
+ memset(&req, 0, sizeof(req));
+ req.nlh.nlmsg_len = sizeof(req);
+ req.nlh.nlmsg_type = TCPDIAG_GETSOCK;
+ /* NLM_F_ROOT: return the complete table instead of a single entry.
+ * NLM_F_MATCH: return all entries matching criteria (not implemented)
+ * NLM_F_REQUEST: must be set on all request messages */
+ req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
+ req.nlh.nlmsg_pid = 0;
+ /* The sequence_number is used to track our messages. Since netlink is not
+ * reliable, we don't want to end up with a corrupt or incomplete old
+ * message in case the system is/was out of memory. */
+ req.nlh.nlmsg_seq = ++sequence_number;
+ req.r.idiag_family = AF_INET;
+ req.r.idiag_states = 0xfff;
+ req.r.idiag_ext = 0;
+
+ memset(&iov, 0, sizeof(iov));
+ iov.iov_base = &req;
+ iov.iov_len = sizeof(req);
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = (void*)&nladdr;
+ msg.msg_namelen = sizeof(nladdr);
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ if (sendmsg (fd, &msg, 0) < 0)
+ {
+ ERROR ("tcpconns plugin: conn_read_netlink: sendmsg(2) failed: %s",
+ sstrerror (errno, buf, sizeof (buf)));
+ close (fd);
+ return (-1);
+ }
+
+ iov.iov_base = buf;
+ iov.iov_len = sizeof(buf);
+
+ while (1)
+ {
+ int status;
+ struct nlmsghdr *h;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = (void*)&nladdr;
+ msg.msg_namelen = sizeof(nladdr);
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ status = recvmsg(fd, (void *) &msg, /* flags = */ 0);
+ if (status < 0)
+ {
+ if ((errno == EINTR) || (errno == EAGAIN))
+ continue;
+
+ ERROR ("tcpconns plugin: conn_read_netlink: recvmsg(2) failed: %s",
+ sstrerror (errno, buf, sizeof (buf)));
+ close (fd);
+ return (-1);
+ }
+ else if (status == 0)
+ {
+ close (fd);
+ DEBUG ("tcpconns plugin: conn_read_netlink: Unexpected zero-sized "
+ "reply from netlink socket.");
+ return (0);
+ }
+
+ h = (struct nlmsghdr*)buf;
+ while (NLMSG_OK(h, status))
+ {
+ if (h->nlmsg_seq != sequence_number)
+ {
+ h = NLMSG_NEXT(h, status);
+ continue;
+ }
+
+ if (h->nlmsg_type == NLMSG_DONE)
+ {
+ close (fd);
+ return (0);
+ }
+ else if (h->nlmsg_type == NLMSG_ERROR)
+ {
+ struct nlmsgerr *msg_error;
+
+ msg_error = NLMSG_DATA(h);
+ WARNING ("tcpconns plugin: conn_read_netlink: Received error %i.",
+ msg_error->error);
+
+ close (fd);
+ return (1);
+ }
+
+ r = NLMSG_DATA(h);
+
+ /* This code does not (need to) distinguish between IPv4 and IPv6. */
+ conn_handle_ports (ntohs(r->id.idiag_sport),
+ ntohs(r->id.idiag_dport),
+ r->idiag_state);
+
+ h = NLMSG_NEXT(h, status);
+ } /* while (NLMSG_OK) */
+ } /* while (1) */
+
+ /* Not reached because the while() loop above handles the exit condition. */
+ return (0);
+} /* int conn_read_netlink */
+