/*

 *  netlink.c - Kernel ACPI Event Netlink Interface

 *

 *  Handles the details of getting kernel ACPI events from netlink.

 *

 *  Inspired by (and in some cases blatantly lifted from) Zhang Rui's

 *  acpi_genl and Alexey Kuznetsov's libnetlink.  Thanks also to Yi Yang

 *  at intel.

 *

 *  Copyright (C) 2008, Ted Felix (www.tedfelix.com)

 *

 *  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  02111-1307  USA

 *

 *  (tabs at 4)

 */

/* system */

#include <stdio.h>

#include <unistd.h>

#include <string.h>

#include <errno.h>

/* local */

#include "libnetlink.h"

#include "genetlink.h"

#include "acpi_genetlink.h"

#include "kacpimon.h"

#include "acpi_ids.h"

#include "connection_list.h"

#include "netlink.h"

/* Dangerous.  Don't try max(i++, j++). */

#define max(a, b)  (((a)>(b))?(a):(b))

static void

format_netlink(struct nlmsghdr *msg)

{

	struct rtattr *tb[ACPI_GENL_ATTR_MAX + 1];

	struct genlmsghdr *ghdr = NLMSG_DATA(msg);

	int len;

	struct rtattr *attrs;

	len = msg->nlmsg_len;

	/* if this message doesn't have the proper family ID, drop it */

	if (msg->nlmsg_type != acpi_ids_getfamily()) {

		printf("Netlink: Message received with improper family ID.\n");

		return;

	}

	len -= NLMSG_LENGTH(GENL_HDRLEN);

	if (len < 0) {

		printf("Netlink: Wrong controller message len: %d\n", len);

		return;

	}

	attrs = (struct rtattr *)((char *)ghdr + GENL_HDRLEN);

	/* parse the attributes in this message */

	parse_rtattr(tb, ACPI_GENL_ATTR_MAX, attrs, len);

	/* if there's an ACPI event attribute... */

	if (tb[ACPI_GENL_ATTR_EVENT]) {

		/* get the actual event struct */

		struct acpi_genl_event *event =

				RTA_DATA(tb[ACPI_GENL_ATTR_EVENT]);

		/* format it */

		printf("netlink: %s %s %08x %08x\n", 

			event->device_class,

			event->bus_id, event->type, event->data);

	}

}

/* (based on rtnl_listen() in libnetlink.c) */

static void

process_netlink(int fd)

{

	int status;

	struct nlmsghdr *h;

	/* the address for recvmsg() */

	struct sockaddr_nl nladdr;

	/* the io vector for recvmsg() */

	struct iovec iov;

	/* recvmsg() parameters */

	struct msghdr msg = {

		.msg_name = &nladdr,

		.msg_namelen = sizeof(nladdr),

		.msg_iov = &iov,

		.msg_iovlen = 1,

	};

	/* buffer for the incoming data */

	char buf[8192];

	/* set up the netlink address */

	memset(&nladdr, 0, sizeof(nladdr));

	nladdr.nl_family = AF_NETLINK;

	nladdr.nl_pid = 0;

	nladdr.nl_groups = 0;

	/* set up the I/O vector */

	iov.iov_base = buf;

	iov.iov_len = sizeof(buf);

	/* read the data into the buffer */

	status = recvmsg(fd, &msg, 0);

	/* if there was a problem, print a message and keep trying */

	if (status < 0) {

		/* if we were interrupted by a signal, bail */

		if (errno == EINTR)

			return;

		printf("Netlink: recvmsg() error: %s (%d)\n",

			   strerror(errno), errno);

		return;

	}

	/* if an orderly shutdown has occurred, we're done */

	if (status == 0) {

		printf("Netlink: Connection closed\n");

		return;

	}

	/* check to see if the address length has changed */

	if (msg.msg_namelen != sizeof(nladdr)) {

		printf("Netlink: Unexpected address length: %d\n", msg.msg_namelen);

		return;

	}

	/* for each message received */

	for (h = (struct nlmsghdr*)buf; (unsigned)status >= sizeof(*h); ) {

		int len = h->nlmsg_len;

		int l = len - sizeof(*h);

		if (l < 0  ||  len > status) {

			if (msg.msg_flags & MSG_TRUNC) {

				printf("Netlink: Message truncated (1)\n");

				return;

			}

			printf("Netlink: Malformed message.  Length: %d\n", len);

			return;

		}

		/* format the message */

		format_netlink(h);

		status -= NLMSG_ALIGN(len);

		h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));

	}

	if (msg.msg_flags & MSG_TRUNC) {

		printf("Netlink: Message truncated (2)\n");

		return;

	}

	if (status) {

		printf("Netlink: Remnant of size %d\n", status);

		return;

	}

	return;

}

/* convert the netlink multicast group number into a bit map */

/* (e.g. 4 => 16, 5 => 32) */

static __u32

nl_mgrp(__u32 group)

{

	if (group > 31) {

		printf("Netlink: Use setsockopt for this group: %d\n", group);

		return 0;

	}

	return group ? (1 << (group - 1)) : 0;

}

void open_netlink(void)

{

	struct rtnl_handle rth;

	struct connection c;

	/* some debugging */

	printf("Netlink ACPI Family ID: %hu\n", acpi_ids_getfamily());

	printf("Netlink ACPI Multicast Group ID: %hu\n", acpi_ids_getgroup());

	/* open the appropriate netlink socket for input */

	if (rtnl_open_byproto(

		&rth, nl_mgrp(acpi_ids_getgroup()), NETLINK_GENERIC) < 0) {

		printf("Netlink: Cannot open generic netlink socket\n");

		return;

	}

	printf("netlink opened successfully\n");

	/* add a connection to the list */

	c.fd = rth.fd;

	c.process = process_netlink;

	add_connection(&c);

}