/* rtnl - rtnetlink utility functions
 *
 * (C) 2004 by Astaro AG, written by Harald Welte <hwelte@astaro.com>
 *
 * This software is free software and licensed under GNU GPLv2. 
 *
 */

/* rtnetlink - routing table netlink interface */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/types.h>

#include <netinet/in.h>

#include <linux/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>

#include "rtnl.h"

#define rtnl_log(x, ...)

static int rtnl_fd;
static int rtnl_seq = 0;
static int rtnl_dump;
static struct sockaddr_nl rtnl_local;

static struct rtnl_handler *handlers = NULL;

static inline struct rtnl_handler *find_handler(u_int16_t type)
{
	struct rtnl_handler *h;
	for (h = handlers; h; h = h->next) {
		if (h->nlmsg_type == type)
			return h;
	}
	return NULL;
}

static int call_handler(u_int16_t type, struct nlmsghdr *hdr)
{
	struct rtnl_handler *h = find_handler(type);

	if (!h) {
		rtnl_log(LOG_DEBUG, "no registered handler for type %u",
			 type);
		return 0;
	}

	return (h->handlefn)(hdr, h->arg);
}

/* rtnl_handler_register - register handler for given nlmsg type
 * @hdlr:	handler structure
 */
int rtnl_handler_register(struct rtnl_handler *hdlr)
{
	rtnl_log(LOG_DEBUG, "registering handler for type %u",
		 hdlr->nlmsg_type);
	hdlr->next = handlers;
	handlers = hdlr;
	return 1;
}

/* rtnl_handler_unregister - unregister handler for given nlmst type
 * @hdlr:	handler structure
 */
int rtnl_handler_unregister(struct rtnl_handler *hdlr)
{
	struct rtnl_handler *h, *prev = NULL;

	rtnl_log(LOG_DEBUG, "unregistering handler for type %u",
		 hdlr->nlmsg_type);

	for (h = handlers; h; h = h->next) {
		if (h == hdlr) {
			if (prev)
				prev->next = h->next;
			else
				handlers = h->next;
			return 1;
		}
		prev = h;
	}
	return 0;
}

/* rtnl_arse_rtattr - parse rtattr */
int rtnl_parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
{
	while (RTA_OK(rta, len)) {
		if (rta->rta_type <= max)
			tb[rta->rta_type] = rta;
		rta = RTA_NEXT(rta,len);
	}
	if (len)
		return -1;
	return 0;
}

/* rtnl_dump_type - ask rtnetlink to dump a specific table
 * @type:	type of table to be dumped
 */
int rtnl_dump_type(unsigned int type)
{
        struct {
                struct nlmsghdr nlh;
                struct rtgenmsg g;
        } req;
        struct sockaddr_nl nladdr;

        memset(&nladdr, 0, sizeof(nladdr));
	memset(&req, 0, sizeof(req));
        nladdr.nl_family = AF_NETLINK;

        req.nlh.nlmsg_len = sizeof(req);
        req.nlh.nlmsg_type = type;
        req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
        req.nlh.nlmsg_pid = 0;
        req.nlh.nlmsg_seq = rtnl_dump = ++rtnl_seq;
        req.g.rtgen_family = AF_INET;

        return sendto(rtnl_fd, (void*)&req, sizeof(req), 0, 
		      (struct sockaddr*)&nladdr, sizeof(nladdr));
}

/* rtnl_receive - receive netlink packets from rtnetlink socket */
int rtnl_receive()
{
	int status;
	char buf[8192];
	struct sockaddr_nl nladdr;
	struct iovec iov = { buf, sizeof(buf) };
	struct nlmsghdr *h;

	struct msghdr msg = {
		(void *)&nladdr, sizeof(nladdr),
		&iov, 1,
		NULL, 0,
		0
	};

	status = recvmsg(rtnl_fd, &msg, 0);
	if (status < 0) {
		if (errno == EINTR)
			return 0;
		rtnl_log(LOG_NOTICE, "OVERRUN on rtnl socket");
		return -1;
	}
	if (status == 0) {
		rtnl_log(LOG_ERROR, "EOF on rtnl socket");
		return -1;
	}
	if (msg.msg_namelen != sizeof(nladdr)) {
		rtnl_log(LOG_ERROR, "invalid address size");
		return -1;
	}

	h = (struct nlmsghdr *) buf;
	while (NLMSG_OK(h, status)) {
#if 0
		if (h->nlmsg_pid != rtnl_local.nl_pid ||
		    h->nlmsg_seq != rtnl_dump) {
			goto skip;
		}
#endif

		if (h->nlmsg_type == NLMSG_DONE) {
			rtnl_log(LOG_NOTICE, "NLMSG_DONE");
			return 0;
		}
		if (h->nlmsg_type == NLMSG_ERROR) { 
			struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
			if (h->nlmsg_len>=NLMSG_LENGTH(sizeof(struct nlmsgerr)))
				errno = -err->error;
			rtnl_log(LOG_ERROR, "NLMSG_ERROR, errnp=%d",
				 errno);
			return -1;
		}

		if (call_handler(h->nlmsg_type, h) == 0) 
			rtnl_log(LOG_NOTICE, "unhandled nlmsg_type %u",
				 h->nlmsg_type);
		h = NLMSG_NEXT(h, status);
	}
	return 1;
}

/* rtnl_init - constructor of rtnetlink module */
int rtnl_init(void)
{
	int addr_len;

	rtnl_local.nl_pid = getpid();
	rtnl_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (rtnl_fd < 0) {
		rtnl_log(LOG_ERROR, "unable to create rtnetlink socket");
		return -1;
	}

	memset(&rtnl_local, 0, sizeof(rtnl_local));
	rtnl_local.nl_family = AF_NETLINK;
	rtnl_local.nl_groups = RTMGRP_IPV4_ROUTE|RTMGRP_IPV4_IFADDR|RTMGRP_LINK;

	if (bind(rtnl_fd, (struct sockaddr *)&rtnl_local, sizeof(rtnl_local)) < 0) {
		rtnl_log(LOG_ERROR, "unable to bind rtnetlink socket");
		return -1;
	}

	addr_len = sizeof(rtnl_local);
	if (getsockname(rtnl_fd, (struct sockaddr *)&rtnl_local, 
			&addr_len) < 0) {
		rtnl_log(LOG_ERROR, "cannot gescockname(rtnl_socket)");
		return -1;
	}

	if (addr_len != sizeof(rtnl_local)) {
		rtnl_log(LOG_ERROR, "invalid address size %u", addr_len);
		return -1;
	}

	if (rtnl_local.nl_family != AF_NETLINK) {
		rtnl_log(LOG_ERROR, "invalid AF %u", rtnl_local.nl_family);
		return -1;
	}

	rtnl_seq = time(NULL);

	return rtnl_fd;
}

/* rtnl_fini - destructor of rtnetlink module */
void rtnl_fini(void)
{
	close(rtnl_fd);
	return;
}