/*	$OpenBSD: switchctl.c,v 1.23 2020/12/25 12:59:53 visa Exp $	*/

/*
 * Copyright (c) 2016 Kazuya GODA <goda@openbsd.org>
 * Copyright (c) 2015, 2016 YASUOKA Masahiko <yasuoka@openbsd.org>
 * Copyright (c) 2015, 2016 Reyk Floeter <reyk@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/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/selinfo.h>
#include <sys/rwlock.h>
#include <sys/proc.h>

#include <net/if.h>
#include <net/rtable.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <net/if_switch.h>

extern struct rwlock	switch_ifs_lk;

/*
 * device part of switch(4)
 */
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/vnode.h>

struct switch_softc *switch_dev2sc(dev_t);
int	switchopen(dev_t, int, int, struct proc *);
int	switchread(dev_t, struct uio *, int);
int	switchwrite(dev_t, struct uio *, int);
int	switchioctl(dev_t, u_long, caddr_t, int, struct proc *);
int	switchclose(dev_t, int, int, struct proc *);
int	switchpoll(dev_t, int, struct proc *);
int	switchkqfilter(dev_t, struct knote *);
void	filt_switch_rdetach(struct knote *);
int	filt_switch_read(struct knote *, long);
void	filt_switch_wdetach(struct knote *);
int	filt_switch_write(struct knote *, long);
int	switch_dev_output(struct switch_softc *, struct mbuf *);
void	switch_dev_wakeup(struct switch_softc *);

const struct filterops switch_rd_filtops = {
	.f_flags	= FILTEROP_ISFD,
	.f_attach	= NULL,
	.f_detach	= filt_switch_rdetach,
	.f_event	= filt_switch_read,
};

const struct filterops switch_wr_filtops = {
	.f_flags	= FILTEROP_ISFD,
	.f_attach	= NULL,
	.f_detach	= filt_switch_wdetach,
	.f_event	= filt_switch_write,
};

struct switch_softc *
switch_dev2sc(dev_t dev)
{
	struct switch_softc	*sc;

	rw_enter_read(&switch_ifs_lk);
	sc = switch_lookup(minor(dev));
	rw_exit_read(&switch_ifs_lk);

	return (sc);
}

int
switchopen(dev_t dev, int flags, int mode, struct proc *p)
{
	struct switch_softc	*sc;
	char			 name[IFNAMSIZ];
	int			 rv, s, error = 0;
	unsigned int		 rdomain = rtable_l2(p->p_p->ps_rtableid);

	if ((sc = switch_dev2sc(dev)) == NULL) {
		snprintf(name, sizeof(name), "switch%d", minor(dev));
		rv = if_clone_create(name, rdomain);
		if (rv != 0)
			return (rv);
		if ((sc = switch_dev2sc(dev)) == NULL)
			return (ENXIO);
	}

	rw_enter_write(&switch_ifs_lk);
	if (sc->sc_swdev != NULL) {
		error = EBUSY;
		goto failed;
	}

	if ((sc->sc_swdev = malloc(sizeof(struct switch_dev), M_DEVBUF,
	    M_DONTWAIT|M_ZERO)) == NULL ) {
		error = ENOBUFS;
		goto failed;
	}

	s = splnet();
	mq_init(&sc->sc_swdev->swdev_outq, 128, IPL_NET);

	sc->sc_swdev->swdev_output = switch_dev_output;
	if (sc->sc_capabilities & SWITCH_CAP_OFP)
		swofp_init(sc);

	splx(s);

 failed:
	rw_exit_write(&switch_ifs_lk);
	return (error);

}

int
switchread(dev_t dev, struct uio *uio, int ioflag)
{
	struct switch_softc	*sc;
	struct mbuf		*m;
	u_int			 len;
	int			 s, error = 0;

	sc = switch_dev2sc(dev);
	if (sc == NULL)
		return (ENXIO);

	if (sc->sc_swdev->swdev_lastm != NULL) {
		m = sc->sc_swdev->swdev_lastm;
		sc->sc_swdev->swdev_lastm = NULL;
		goto skip_dequeue;
	}

 dequeue_next:
	s = splnet();
	while ((m = mq_dequeue(&sc->sc_swdev->swdev_outq)) == NULL) {
		if (ISSET(ioflag, IO_NDELAY)) {
			error = EWOULDBLOCK;
			goto failed;
		}
		sc->sc_swdev->swdev_waiting = 1;
		error = tsleep_nsec(sc, (PZERO + 1)|PCATCH, "switchread",
		    INFSLP);
		if (error != 0)
			goto failed;
		/* sc might be deleted while sleeping */
		sc = switch_dev2sc(dev);
		if (sc == NULL) {
			error = ENXIO;
			goto failed;
		}
	}
	splx(s);

 skip_dequeue:
	while (uio->uio_resid > 0) {
		len = ulmin(uio->uio_resid, m->m_len);
		if ((error = uiomove(mtod(m, caddr_t), len, uio)) != 0) {
			/* Save it so user can recover from EFAULT. */
			sc->sc_swdev->swdev_lastm = m;
			return (error);
		}

		/* Handle partial reads. */
		if (uio->uio_resid == 0) {
			if (len < m->m_len)
				m_adj(m, len);
			else
				m = m_free(m);
			sc->sc_swdev->swdev_lastm = m;
			break;
		}

		/*
		 * After consuming data from this mbuf test if we
		 * have to dequeue a new chain.
		 */
		m = m_free(m);
		if (m == NULL)
			goto dequeue_next;
	}

	return (0);
failed:
	splx(s);
	return (error);
}

int
switchwrite(dev_t dev, struct uio *uio, int ioflag)
{
	struct switch_softc	*sc = NULL;
	struct mbuf		*m, *n, *mhead, *mtail = NULL;
	int			 s, error, trailing;
	size_t			 len;

	if (uio->uio_resid == 0)
		return (0);

	len = uio->uio_resid;

	sc = switch_dev2sc(dev);
	if (sc == NULL)
		return (ENXIO);

	if (sc->sc_swdev->swdev_inputm == NULL) {
		MGETHDR(m, M_DONTWAIT, MT_DATA);
		if (m == NULL)
			return (ENOBUFS);
		if (len >= MHLEN) {
			MCLGETL(m, M_DONTWAIT, MIN(MAXMCLBYTES, len));
			if ((m->m_flags & M_EXT) == 0) {
				m_free(m);
				return (ENOBUFS);
			}
		}
		mhead = m;

		/* m_trailingspace() uses this to calculate space. */
		m->m_len = 0;
	} else {
		/* Recover the mbuf from the last write and get its tail. */
		mhead = sc->sc_swdev->swdev_inputm;
		for (m = mhead; m->m_next != NULL; m = m->m_next)
			/* NOTHING */;

		sc->sc_swdev->swdev_inputm = NULL;
	}
	KASSERT(mhead->m_flags & M_PKTHDR);

	while (len) {
		trailing = ulmin(m_trailingspace(m), len);
		if ((error = uiomove(mtod(m, caddr_t) + m->m_len, trailing,
		    uio)) != 0)
			goto save_return;

		len -= trailing;
		mhead->m_pkthdr.len += trailing;
		m->m_len += trailing;
		if (len == 0)
			break;

		MGET(n, M_DONTWAIT, MT_DATA);
		if (n == NULL) {
			error = ENOBUFS;
			goto save_return;
		}
		if (len >= MLEN) {
			MCLGETL(n, M_DONTWAIT, MIN(MAXMCLBYTES, len));
			if ((n->m_flags & M_EXT) == 0) {
				m_free(n);
				error = ENOBUFS;
				goto save_return;
			}
		}
		n->m_len = 0;

		m->m_next = n;
		m = n;
	}

	/* Loop until there is no more complete OFP packets. */
	while (ofp_split_mbuf(mhead, &mtail) == 0) {
		s = splnet();
		sc->sc_swdev->swdev_input(sc, mhead);
		splx(s);

		/* We wrote everything, just quit. */
		if (mtail == NULL)
			return (0);

		mhead = mtail;
	}

	/* Save the head, because ofp_split_mbuf failed. */
	sc->sc_swdev->swdev_inputm = mhead;

	return (0);

 save_return:
	/* Save it so user can recover from errors later. */
	sc->sc_swdev->swdev_inputm = mhead;
	return (error);
}

int
switchioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p)
{
	int			 error;

	switch (cmd) {
	case FIONBIO:
	case FIOASYNC:
	case FIONREAD:
		return (0);
	default:
		error = ENOTTY;
		break;
	}

	return (error);
}

int
switchclose(dev_t dev, int flags, int mode, struct proc *p)
{
	struct switch_softc	*sc;

	rw_enter_write(&switch_ifs_lk);
	sc = switch_lookup(minor(dev));
	if (sc != NULL && sc->sc_swdev != NULL) {
		m_freem(sc->sc_swdev->swdev_lastm);
		m_freem(sc->sc_swdev->swdev_inputm);
		mq_purge(&sc->sc_swdev->swdev_outq);
		free(sc->sc_swdev, M_DEVBUF, sizeof(struct switch_dev));
		sc->sc_swdev = NULL;
	}
	rw_exit_write(&switch_ifs_lk);

	return (0);
}

void
switch_dev_destroy(struct switch_softc *sc)
{
	int	 s;

	if (sc->sc_swdev == NULL)
		return;
	rw_enter_write(&switch_ifs_lk);
	if (sc->sc_swdev != NULL) {
		switch_dev_wakeup(sc);

		s = splhigh();
		klist_invalidate(&sc->sc_swdev->swdev_rsel.si_note);
		klist_invalidate(&sc->sc_swdev->swdev_wsel.si_note);
		splx(s);

		m_freem(sc->sc_swdev->swdev_lastm);
		m_freem(sc->sc_swdev->swdev_inputm);
		mq_purge(&sc->sc_swdev->swdev_outq);
		free(sc->sc_swdev, M_DEVBUF, sizeof(struct switch_dev));
		sc->sc_swdev = NULL;
	}
	rw_exit_write(&switch_ifs_lk);
}

int
switchpoll(dev_t dev, int events, struct proc *p)
{
	int			 revents = 0;
	struct switch_softc	*sc = switch_dev2sc(dev);

	if (sc == NULL)
		return (POLLERR);

	if (events & (POLLIN | POLLRDNORM)) {
		if (!mq_empty(&sc->sc_swdev->swdev_outq) ||
		    sc->sc_swdev->swdev_lastm != NULL)
			revents |= events & (POLLIN | POLLRDNORM);
	}
	if (events & (POLLOUT | POLLWRNORM))
		revents |= events & (POLLOUT | POLLWRNORM);
	if (revents == 0) {
		if (events & (POLLIN | POLLRDNORM))
			selrecord(p, &sc->sc_swdev->swdev_rsel);
	}

	return (revents);
}

int
switchkqfilter(dev_t dev, struct knote *kn)
{
	struct switch_softc	*sc = switch_dev2sc(dev);
	struct klist		*klist;

	if (sc == NULL)
		return (ENXIO);

	switch (kn->kn_filter) {
	case EVFILT_READ:
		klist = &sc->sc_swdev->swdev_rsel.si_note;
		kn->kn_fop = &switch_rd_filtops;
		break;
	case EVFILT_WRITE:
		klist = &sc->sc_swdev->swdev_wsel.si_note;
		kn->kn_fop = &switch_wr_filtops;
		break;
	default:
		return (EINVAL);
	}

	kn->kn_hook = (caddr_t)sc;

	klist_insert_locked(klist, kn);

	return (0);
}

void
filt_switch_rdetach(struct knote *kn)
{
	struct switch_softc	*sc = (struct switch_softc *)kn->kn_hook;
	struct klist		*klist = &sc->sc_swdev->swdev_rsel.si_note;

	klist_remove_locked(klist, kn);
}

int
filt_switch_read(struct knote *kn, long hint)
{
	struct switch_softc	*sc = (struct switch_softc *)kn->kn_hook;

	if (!mq_empty(&sc->sc_swdev->swdev_outq) ||
	    sc->sc_swdev->swdev_lastm != NULL) {
		kn->kn_data = mq_len(&sc->sc_swdev->swdev_outq) +
		    (sc->sc_swdev->swdev_lastm != NULL);
		return (1);
	}

	return (0);
}

void
filt_switch_wdetach(struct knote *kn)
{
	struct switch_softc	*sc = (struct switch_softc *)kn->kn_hook;
	struct klist		*klist = &sc->sc_swdev->swdev_wsel.si_note;

	klist_remove_locked(klist, kn);
}

int
filt_switch_write(struct knote *kn, long hint)
{
	/* Always writable */
	return (1);
}

int
switch_dev_output(struct switch_softc *sc, struct mbuf *m)
{
	if (mq_enqueue(&sc->sc_swdev->swdev_outq, m) != 0)
		return (-1);
	switch_dev_wakeup(sc);

	return (0);
}

void
switch_dev_wakeup(struct switch_softc *sc)
{
	if (sc->sc_swdev->swdev_waiting) {
		sc->sc_swdev->swdev_waiting = 0;
		wakeup((caddr_t)sc);
	}
	selwakeup(&sc->sc_swdev->swdev_rsel);
}