/*	$OpenBSD: kroute.c,v 1.14 2017/07/24 11:00:01 friehm Exp $ */

/*
 * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/tree.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "dvmrp.h"
#include "dvmrpd.h"
#include "log.h"

struct {
	u_int32_t		rtseq;
	pid_t			pid;
	struct event		ev;
} kr_state;

struct kif_node {
	RB_ENTRY(kif_node)	 entry;
	struct kif		 k;
};

int	kif_compare(struct kif_node *, struct kif_node *);

struct kif_node		*kif_find(int);
int			 kif_insert(struct kif_node *);
int			 kif_remove(struct kif_node *);
void			 kif_clear(void);

in_addr_t	prefixlen2mask(u_int8_t);
void		get_rtaddrs(int, struct sockaddr *, struct sockaddr **);
void		if_change(u_short, int, struct if_data *);
void		if_announce(void *);

int		fetchifs(int);

RB_HEAD(kif_tree, kif_node)		kit;
RB_PROTOTYPE(kif_tree, kif_node, entry, kif_compare)
RB_GENERATE(kif_tree, kif_node, entry, kif_compare)

int
kif_init(void)
{
	RB_INIT(&kit);

	if (fetchifs(0) == -1)
		return (-1);

	return (0);
}

int
kr_init(void)
{
	int opt, fd;

	if ((fd = socket(AF_ROUTE, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK,
	    0)) == -1) {
		log_warn("kr_init: socket");
		return (-1);
	}

	/* not interested in my own messages */
	if (setsockopt(fd, SOL_SOCKET, SO_USELOOPBACK, &opt, sizeof(opt)) == -1)
		log_warn("kr_init: setsockopt");	/* not fatal */

	kr_state.pid = getpid();
	kr_state.rtseq = 1;

	event_set(&kr_state.ev, fd, EV_READ | EV_PERSIST,
	    kr_dispatch_msg, NULL);
	event_add(&kr_state.ev, NULL);

	return (0);
}

void
kr_shutdown(void)
{
	kif_clear();
	close(EVENT_FD((&kr_state.ev)));
}

void
kr_ifinfo(char *ifname)
{
	struct kif_node	*kif;

	RB_FOREACH(kif, kif_tree, &kit)
		if (!strcmp(ifname, kif->k.ifname)) {
			main_imsg_compose_dvmrpe(IMSG_CTL_IFINFO, 0,
			    &kif->k, sizeof(kif->k));
			return;
		}
}

/* rb-tree compare */
int
kif_compare(struct kif_node *a, struct kif_node *b)
{
	return (b->k.ifindex - a->k.ifindex);
}

struct kif_node *
kif_find(int ifindex)
{
	struct kif_node	s;

	memset(&s, 0, sizeof(s));
	s.k.ifindex = ifindex;

	return (RB_FIND(kif_tree, &kit, &s));
}

struct kif *
kif_findname(char *ifname)
{
	struct kif_node	*kif;

	RB_FOREACH(kif, kif_tree, &kit)
		if (!strcmp(ifname, kif->k.ifname))
			return (&kif->k);

	return (NULL);
}

int
kif_insert(struct kif_node *kif)
{
	if (RB_INSERT(kif_tree, &kit, kif) != NULL) {
		log_warnx("RB_INSERT(kif_tree, &kit, kif)");
		free(kif);
		return (-1);
	}

	return (0);
}

int
kif_remove(struct kif_node *kif)
{
	if (RB_REMOVE(kif_tree, &kit, kif) == NULL) {
		log_warnx("RB_REMOVE(kif_tree, &kit, kif)");
		return (-1);
	}

	free(kif);
	return (0);
}

void
kif_clear(void)
{
	struct kif_node	*kif;

	while ((kif = RB_MIN(kif_tree, &kit)) != NULL)
		kif_remove(kif);
}

/* misc */
u_int8_t
prefixlen_classful(in_addr_t ina)
{
	/* it hurt to write this. */

	if (ina >= 0xf0000000U)		/* class E */
		return (32);
	else if (ina >= 0xe0000000U)	/* class D */
		return (4);
	else if (ina >= 0xc0000000U)	/* class C */
		return (24);
	else if (ina >= 0x80000000U)	/* class B */
		return (16);
	else				/* class A */
		return (8);
}

u_int8_t
mask2prefixlen(in_addr_t ina)
{
	if (ina == 0)
		return (0);
	else
		return (33 - ffs(ntohl(ina)));
}

in_addr_t
prefixlen2mask(u_int8_t prefixlen)
{
	if (prefixlen == 0)
		return (0);

	return (0xffffffff << (32 - prefixlen));
}

void
if_change(u_short ifindex, int flags, struct if_data *ifd)
{
	struct kif_node		*kif;
	u_int8_t		 reachable;

	if ((kif = kif_find(ifindex)) == NULL) {
		log_warnx("interface with index %u not found",
		    ifindex);
		return;
	}

	kif->k.flags = flags;
	kif->k.link_state = ifd->ifi_link_state;
	kif->k.if_type = ifd->ifi_type;
	kif->k.baudrate = ifd->ifi_baudrate;

	if ((reachable = (flags & IFF_UP) &&
	    LINK_STATE_IS_UP(ifd->ifi_link_state)) == kif->k.nh_reachable)
		return;		/* nothing changed wrt nexthop validity */

	kif->k.nh_reachable = reachable;
	main_imsg_compose_dvmrpe(IMSG_IFINFO, 0, &kif->k, sizeof(kif->k));
}

void
if_announce(void *msg)
{
	struct if_announcemsghdr	*ifan;
	struct kif_node			*kif;

	ifan = msg;

	switch (ifan->ifan_what) {
	case IFAN_ARRIVAL:
		if ((kif = calloc(1, sizeof(struct kif_node))) == NULL) {
			log_warn("if_announce");
			return;
		}

		kif->k.ifindex = ifan->ifan_index;
		strlcpy(kif->k.ifname, ifan->ifan_name, sizeof(kif->k.ifname));
		kif_insert(kif);
		break;
	case IFAN_DEPARTURE:
		kif = kif_find(ifan->ifan_index);
		kif_remove(kif);
		break;
	}
}

/* rtsock */
#define ROUNDUP(a) \
	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))

void
get_rtaddrs(int addrs, struct sockaddr *sa, struct sockaddr **rti_info)
{
	int	i;

	for (i = 0; i < RTAX_MAX; i++) {
		if (addrs & (1 << i)) {
			rti_info[i] = sa;
			sa = (struct sockaddr *)((char *)(sa) +
			    ROUNDUP(sa->sa_len));
		} else
			rti_info[i] = NULL;
	}
}

int
fetchifs(int ifindex)
{
	size_t			 len;
	int			 mib[6];
	char			*buf, *next, *lim;
	struct if_msghdr	 ifm;
	struct kif_node		*kif;
	struct sockaddr		*sa, *rti_info[RTAX_MAX];
	struct sockaddr_dl	*sdl;

	mib[0] = CTL_NET;
	mib[1] = PF_ROUTE;
	mib[2] = 0;
	mib[3] = AF_INET;
	mib[4] = NET_RT_IFLIST;
	mib[5] = ifindex;

	if (sysctl(mib, 6, NULL, &len, NULL, 0) == -1) {
		log_warn("sysctl");
		return (-1);
	}
	if ((buf = malloc(len)) == NULL) {
		log_warn("fetchif");
		return (-1);
	}
	if (sysctl(mib, 6, buf, &len, NULL, 0) == -1) {
		log_warn("sysctl");
		free(buf);
		return (-1);
	}

	lim = buf + len;
	for (next = buf; next < lim; next += ifm.ifm_msglen) {
		memcpy(&ifm, next, sizeof(ifm));
		sa = (struct sockaddr *)(next + sizeof(ifm));
		get_rtaddrs(ifm.ifm_addrs, sa, rti_info);

		if (ifm.ifm_version != RTM_VERSION)
			continue;
		if (ifm.ifm_type != RTM_IFINFO)
			continue;

		if ((kif = calloc(1, sizeof(struct kif_node))) == NULL) {
			log_warn("fetchifs");
			free(buf);
			return (-1);
		}

		kif->k.ifindex = ifm.ifm_index;
		kif->k.flags = ifm.ifm_flags;
		kif->k.link_state = ifm.ifm_data.ifi_link_state;
		kif->k.if_type = ifm.ifm_data.ifi_type;
		kif->k.baudrate = ifm.ifm_data.ifi_baudrate;
		kif->k.mtu = ifm.ifm_data.ifi_mtu;
		kif->k.nh_reachable = (kif->k.flags & IFF_UP) &&
		    LINK_STATE_IS_UP(ifm.ifm_data.ifi_link_state);
		if ((sa = rti_info[RTAX_IFP]) != NULL)
			if (sa->sa_family == AF_LINK) {
				sdl = (struct sockaddr_dl *)sa;
				if (sdl->sdl_nlen >= sizeof(kif->k.ifname))
					memcpy(kif->k.ifname, sdl->sdl_data,
					    sizeof(kif->k.ifname) - 1);
				else if (sdl->sdl_nlen > 0)
					memcpy(kif->k.ifname, sdl->sdl_data,
					    sdl->sdl_nlen);
				/* string already terminated via calloc() */
			}

		kif_insert(kif);
	}
	free(buf);
	return (0);
}

void
kr_dispatch_msg(int fd, short event, void *bula)
{
	char			 buf[RT_BUF_SIZE];
	ssize_t			 n;
	char			*next, *lim;
	struct rt_msghdr	*rtm;
	struct if_msghdr	 ifm;

	if ((n = read(fd, &buf, sizeof(buf))) == -1) {
		if (errno == EAGAIN || errno == EINTR)
			return;
		fatal("dispatch_rtmsg: read error");
	}

	if (n == 0)
		fatalx("routing socket closed");

	lim = buf + n;
	for (next = buf; next < lim; next += rtm->rtm_msglen) {
		rtm = (struct rt_msghdr *)next;
		if (lim < next + sizeof(u_short) ||
		    lim < next + rtm->rtm_msglen)
			fatalx("dispatch_rtmsg: partial rtm in buffer");
		if (rtm->rtm_version != RTM_VERSION)
			continue;

		switch (rtm->rtm_type) {
		case RTM_IFINFO:
			memcpy(&ifm, next, sizeof(ifm));
			if_change(ifm.ifm_index, ifm.ifm_flags,
			    &ifm.ifm_data);
			break;
		case RTM_IFANNOUNCE:
			if_announce(next);
			break;
		default:
			/* ignore for now */
			break;
		}
	}
}