/*	$NetBSD: aarp.c,v 1.46 2023/07/31 01:24:36 dholland Exp $	*/

/*
 * Copyright (c) 1990,1991 Regents of The University of Michigan.
 * All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby granted,
 * provided that the above copyright notice appears in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation, and that the name of The University
 * of Michigan not be used in advertising or publicity pertaining to
 * distribution of the software without specific, written prior
 * permission. This software is supplied as is without expressed or
 * implied warranties of any kind.
 *
 * This product includes software developed by the University of
 * California, Berkeley and its contributors.
 *
 *	Research Systems Unix Group
 *	The University of Michigan
 *	c/o Wesley Craig
 *	535 W. William Street
 *	Ann Arbor, Michigan
 *	+1-313-764-2278
 *	netatalk@umich.edu
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: aarp.c,v 1.46 2023/07/31 01:24:36 dholland Exp $");

#include "opt_mbuftrace.h"
#include "opt_atalk.h"

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/proc.h>
#include <sys/mbuf.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/socketvar.h>
#include <net/if.h>
#include <net/route.h>
#include <net/if_ether.h>
#include <net/if_dl.h>
#include <netinet/in.h>
#undef s_net

#include <netatalk/at.h>
#include <netatalk/at_var.h>
#include <netatalk/aarp.h>
#include <netatalk/ddp_var.h>
#include <netatalk/phase2.h>
#include <netatalk/at_extern.h>

static struct aarptab *aarptnew(const struct at_addr *);
static void aarptfree(struct aarptab *);
static void at_aarpinput(struct ifnet *, struct mbuf *);
static void aarptimer(void *);
static void aarpwhohas(struct ifnet *, const struct sockaddr_at *);

#define AARPTAB_BSIZ	9
#define AARPTAB_NB	19
#define AARPTAB_SIZE	(AARPTAB_BSIZ * AARPTAB_NB)
struct aarptab  aarptab[AARPTAB_SIZE];

#define AARPTAB_HASH(a) \
    ((((a).s_net << 8 ) + (a).s_node ) % AARPTAB_NB )

#define AARPTAB_LOOK(aat, addr) { 				\
	int n;							\
								\
	(aat) = &aarptab[AARPTAB_HASH(addr) * AARPTAB_BSIZ];	\
	for (n = 0; n < AARPTAB_BSIZ; n++, (aat)++) {		\
		if ((aat)->aat_ataddr.s_net == (addr).s_net &&	\
	            (aat)->aat_ataddr.s_node == (addr).s_node)	\
			break;					\
	}							\
	if (n >= AARPTAB_BSIZ) {				\
		(aat) = 0;					\
	}							\
}

#define AARPT_AGE	(60 * 1)
#define AARPT_KILLC	20
#define AARPT_KILLI	3

const u_char atmulticastaddr[6] = {
	0x09, 0x00, 0x07, 0xff, 0xff, 0xff
};

const u_char at_org_code[3] = {
	0x08, 0x00, 0x07
};
const u_char aarp_org_code[3] = {
	0x00, 0x00, 0x00
};

struct callout aarptimer_callout;
#ifdef MBUFTRACE
struct mowner aarp_mowner = MOWNER_INIT("atalk", "arp");
#endif

/*ARGSUSED*/
static void
aarptimer(void *ignored)
{
	struct aarptab *aat;
	int             i, s;

	mutex_enter(softnet_lock);
	callout_reset(&aarptimer_callout, AARPT_AGE * hz, aarptimer, NULL);
	aat = aarptab;
	for (i = 0; i < AARPTAB_SIZE; i++, aat++) {
		int killtime = (aat->aat_flags & ATF_COM) ? AARPT_KILLC :
		    AARPT_KILLI;
		if (aat->aat_flags == 0 || (aat->aat_flags & ATF_PERM))
			continue;
		if (++aat->aat_timer < killtime)
			continue;
		s = splnet();
		aarptfree(aat);
		splx(s);
	}
	mutex_exit(softnet_lock);
}

/*
 * search through the network addresses to find one that includes the given
 * network.. remember to take netranges into consideration.
 */
struct ifaddr *
at_ifawithnet(const struct sockaddr_at *sat, struct ifnet *ifp)
{
	struct ifaddr *ifa;
	struct sockaddr_at *sat2;
	struct netrange *nr;

	IFADDR_READER_FOREACH(ifa, ifp) {
		if (ifa->ifa_addr->sa_family != AF_APPLETALK)
			continue;

		sat2 = satosat(ifa->ifa_addr);
		if (sat2->sat_addr.s_net == sat->sat_addr.s_net)
			break;

		nr = (struct netrange *) (sat2->sat_zero);
		if ((nr->nr_phase == 2)
		    && (ntohs(nr->nr_firstnet) <= ntohs(sat->sat_addr.s_net))
		    && (ntohs(nr->nr_lastnet) >= ntohs(sat->sat_addr.s_net)))
			break;
	}

	return ifa;
}

static void
aarpwhohas(struct ifnet *ifp, const struct sockaddr_at *sat)
{
	struct mbuf    *m;
	struct ether_header *eh;
	struct ether_aarp *ea;
	struct at_ifaddr *aa;
	struct llc     *llc;
	struct sockaddr sa;

	if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
		return;

	MCLAIM(m, &aarp_mowner);
	m->m_len = sizeof(*ea);
	m->m_pkthdr.len = sizeof(*ea);
	m_align(m, sizeof(*ea));

	ea = mtod(m, struct ether_aarp *);
	memset(ea, 0, sizeof(*ea));

	ea->aarp_hrd = htons(AARPHRD_ETHER);
	ea->aarp_pro = htons(ETHERTYPE_ATALK);
	ea->aarp_hln = sizeof(ea->aarp_sha);
	ea->aarp_pln = sizeof(ea->aarp_spu);
	ea->aarp_op = htons(AARPOP_REQUEST);
	memcpy(ea->aarp_sha, CLLADDR(ifp->if_sadl), sizeof(ea->aarp_sha));

	/*
         * We need to check whether the output ethernet type should
         * be phase 1 or 2. We have the interface that we'll be sending
         * the aarp out. We need to find an AppleTalk network on that
         * interface with the same address as we're looking for. If the
         * net is phase 2, generate an 802.2 and SNAP header.
         */
	if ((aa = (struct at_ifaddr *) at_ifawithnet(sat, ifp)) == NULL) {
		m_freem(m);
		return;
	}
	eh = (struct ether_header *) sa.sa_data;

	if (aa->aa_flags & AFA_PHASE2) {
		memcpy(eh->ether_dhost, atmulticastaddr,
		    sizeof(eh->ether_dhost));
		eh->ether_type = 0;	/* if_output will treat as 802 */
		M_PREPEND(m, sizeof(struct llc), M_DONTWAIT);
		if (!m)
			return;

		llc = mtod(m, struct llc *);
		llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
		llc->llc_control = LLC_UI;
		memcpy(llc->llc_org_code, aarp_org_code, sizeof(aarp_org_code));
		llc->llc_ether_type = htons(ETHERTYPE_AARP);

		memcpy(ea->aarp_spnet, &AA_SAT(aa)->sat_addr.s_net,
		      sizeof(ea->aarp_spnet));
		memcpy(ea->aarp_tpnet, &sat->sat_addr.s_net,
		      sizeof(ea->aarp_tpnet));
		ea->aarp_spnode = AA_SAT(aa)->sat_addr.s_node;
		ea->aarp_tpnode = sat->sat_addr.s_node;
	} else {
		memcpy(eh->ether_dhost, etherbroadcastaddr,
		    sizeof(eh->ether_dhost));
		eh->ether_type = htons(ETHERTYPE_AARP);

		ea->aarp_spa = AA_SAT(aa)->sat_addr.s_node;
		ea->aarp_tpa = sat->sat_addr.s_node;
	}

	/* If we are talking to ourselves, use the loopback interface. */
	if (AA_SAT(aa)->sat_addr.s_net == sat->sat_addr.s_net &&
	    AA_SAT(aa)->sat_addr.s_node == sat->sat_addr.s_node)
		ifp = lo0ifp;

#ifdef NETATALKDEBUG
	printf("aarp: sending request via %u.%u through %s seeking %u.%u\n",
	    ntohs(AA_SAT(aa)->sat_addr.s_net),
	    AA_SAT(aa)->sat_addr.s_node,
	    ifp->if_xname,
	    ntohs(sat->sat_addr.s_net),
	    sat->sat_addr.s_node);
#endif /* NETATALKDEBUG */

	sa.sa_len = sizeof(struct sockaddr);
	sa.sa_family = AF_UNSPEC;
	if_output_lock(ifp, ifp, m, &sa, NULL);	/* XXX NULL should be routing */
						/* information */
}

int
aarpresolve(struct ifnet *ifp, struct mbuf *m,
    const struct sockaddr_at *destsat, u_char *desten)
{
	struct at_ifaddr *aa;
	struct aarptab *aat;
	int             s;

	if (at_broadcast(destsat)) {
		struct ifaddr *ifa;

		s = pserialize_read_enter();
		ifa = at_ifawithnet(destsat, ifp);
		if (ifa == NULL) {
			pserialize_read_exit(s);
			m_freem(m);
			return (0);
		}
		aa = (struct at_ifaddr *)ifa;

		if (aa->aa_flags & AFA_PHASE2)
			memcpy(desten, atmulticastaddr,
			    sizeof(atmulticastaddr));
		else
			memcpy(desten, etherbroadcastaddr,
			    sizeof(etherbroadcastaddr));
		pserialize_read_exit(s);
		return 1;
	}
	s = splnet();
	AARPTAB_LOOK(aat, destsat->sat_addr);
	if (aat == 0) {		/* No entry */
		aat = aarptnew(&destsat->sat_addr);
		if (aat == 0)
			panic("aarpresolve: no free entry");

		aat->aat_hold = m;
		aarpwhohas(ifp, destsat);
		splx(s);
		return 0;
	}

	/* found an entry */
	aat->aat_timer = 0;
	if (aat->aat_flags & ATF_COM) {	/* entry is COMplete */
		memcpy(desten, aat->aat_enaddr, sizeof(aat->aat_enaddr));
		splx(s);
		return 1;
	}

	/* entry has not completed */
	if (aat->aat_hold)
		m_freem(aat->aat_hold);
	aat->aat_hold = m;
	aarpwhohas(ifp, destsat);
	splx(s);

	return 0;
}

void
aarpinput(struct ifnet *ifp, struct mbuf *m)
{
	struct arphdr  *ar;

	if (ifp->if_flags & IFF_NOARP)
		goto out;

	if (m->m_len < sizeof(struct arphdr))
		goto out;

	ar = mtod(m, struct arphdr *);
	if (ntohs(ar->ar_hrd) != AARPHRD_ETHER)
		goto out;

	if (m->m_len < sizeof(struct arphdr) + 2 * ar->ar_hln + 2 * ar->ar_pln)
		goto out;

	switch (ntohs(ar->ar_pro)) {
	case ETHERTYPE_ATALK:
		at_aarpinput(ifp, m);
		return;

	default:
		break;
	}

out:
	m_freem(m);
}

static void
at_aarpinput(struct ifnet *ifp, struct mbuf *m)
{
	struct ether_aarp *ea;
	struct at_ifaddr *aa;
	struct aarptab *aat;
	struct ether_header *eh;
	struct llc     *llc;
	struct sockaddr_at sat;
	struct sockaddr sa;
	struct at_addr  spa, tpa, ma;
	int             op;
	u_int16_t       net;
	int		s;
	struct psref	psref;
	struct ifaddr *ifa;

	/* We should also check ar_hln and ar_pln. */
	if ((m = m_pullup(m, sizeof(struct ether_aarp))) == NULL) {
		return;
	}

	ea = mtod(m, struct ether_aarp *);

	/* Check to see if from my hardware address */
	if (!memcmp(ea->aarp_sha, CLLADDR(ifp->if_sadl), sizeof(ea->aarp_sha))) {
		m_freem(m);
		return;
	}
	op = ntohs(ea->aarp_op);
	memcpy(&net, ea->aarp_tpnet, sizeof(net));

	if (net != 0) {		/* should be ATADDR_ANYNET? */
		sat.sat_len = sizeof(struct sockaddr_at);
		sat.sat_family = AF_APPLETALK;
		sat.sat_addr.s_net = net;

		s = pserialize_read_enter();
		ifa = at_ifawithnet(&sat, ifp);
		if (ifa == NULL) {
			pserialize_read_exit(s);
			m_freem(m);
			return;
		}
		ifa_acquire(ifa, &psref);
		pserialize_read_exit(s);
		aa = (struct at_ifaddr *)ifa;

		memcpy(&spa.s_net, ea->aarp_spnet, sizeof(spa.s_net));
		memcpy(&tpa.s_net, ea->aarp_tpnet, sizeof(tpa.s_net));
	} else {
		/*
		 * Since we don't know the net, we just look for the first
		 * phase 1 address on the interface.
		 */
		s = pserialize_read_enter();
		IFADDR_READER_FOREACH(ifa, ifp) {
			aa = (struct at_ifaddr *)ifa;
			if (AA_SAT(aa)->sat_family == AF_APPLETALK &&
			    (aa->aa_flags & AFA_PHASE2) == 0) {
				ifa_acquire(ifa, &psref);
				break;
			}
		}
		pserialize_read_exit(s);

		if (ifa == NULL) {
			m_freem(m);
			return;
		}
		tpa.s_net = spa.s_net = AA_SAT(aa)->sat_addr.s_net;
	}

	spa.s_node = ea->aarp_spnode;
	tpa.s_node = ea->aarp_tpnode;
	ma.s_net = AA_SAT(aa)->sat_addr.s_net;
	ma.s_node = AA_SAT(aa)->sat_addr.s_node;

	/*
         * This looks like it's from us.
         */
	if (spa.s_net == ma.s_net && spa.s_node == ma.s_node) {
		if (aa->aa_flags & AFA_PROBING) {
			/*
		         * We're probing, someone either responded to our
			 * probe, or probed for the same address we'd like
			 * to use. Change the address we're probing for.
		         */
			callout_stop(&aa->aa_probe_ch);
			wakeup(aa);
			m_freem(m);
			goto out;
		} else if (op != AARPOP_PROBE) {
			/*
		         * This is not a probe, and we're not probing.
			 * This means that someone's saying they have the same
			 * source address as the one we're using. Get upset...
		         */
			log(LOG_ERR, "aarp: duplicate AT address!! %s\n",
			    ether_sprintf(ea->aarp_sha));
			m_freem(m);
			goto out;
		}
	}
	AARPTAB_LOOK(aat, spa);
	if (aat) {
		if (op == AARPOP_PROBE) {
			/*
		         * Someone's probing for spa, deallocate the one we've
			 * got, so that if the prober keeps the address, we'll
			 * be able to arp for him.
		         */
			aarptfree(aat);
			m_freem(m);
			goto out;
		}
		memcpy(aat->aat_enaddr, ea->aarp_sha, sizeof(ea->aarp_sha));
		aat->aat_flags |= ATF_COM;
		if (aat->aat_hold) {
			sat.sat_len = sizeof(struct sockaddr_at);
			sat.sat_family = AF_APPLETALK;
			sat.sat_addr = spa;
			if_output_lock(ifp, ifp, aat->aat_hold,
			    (struct sockaddr *) & sat, NULL);	/* XXX */
			aat->aat_hold = 0;
		}
	}
	if (aat == 0 && tpa.s_net == ma.s_net && tpa.s_node == ma.s_node
	    && op != AARPOP_PROBE) {
		if ((aat = aarptnew(&spa)) != NULL) {
			memcpy(aat->aat_enaddr, ea->aarp_sha,
			    sizeof(ea->aarp_sha));
			aat->aat_flags |= ATF_COM;
		}
	}
	/*
         * Don't respond to responses, and never respond if we're
         * still probing.
         */
	if (tpa.s_net != ma.s_net || tpa.s_node != ma.s_node ||
	    op == AARPOP_RESPONSE || (aa->aa_flags & AFA_PROBING)) {
		m_freem(m);
		goto out;
	}

	/*
	 * Prepare and send AARP-response.
	 */
	m->m_len = sizeof(*ea);
	m->m_pkthdr.len = sizeof(*ea);
	memcpy(ea->aarp_tha, ea->aarp_sha, sizeof(ea->aarp_sha));
	memcpy(ea->aarp_sha, CLLADDR(ifp->if_sadl), sizeof(ea->aarp_sha));

	/* XXX */
	eh = (struct ether_header *) sa.sa_data;
	memcpy(eh->ether_dhost, ea->aarp_tha, sizeof(eh->ether_dhost));

	if (aa->aa_flags & AFA_PHASE2) {
		M_PREPEND(m, sizeof(struct llc), M_DONTWAIT);
		if (m == NULL)
			goto out;

		llc = mtod(m, struct llc *);
		llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
		llc->llc_control = LLC_UI;
		memcpy(llc->llc_org_code, aarp_org_code, sizeof(aarp_org_code));
		llc->llc_ether_type = htons(ETHERTYPE_AARP);

		memcpy(ea->aarp_tpnet, ea->aarp_spnet, sizeof(ea->aarp_tpnet));
		memcpy(ea->aarp_spnet, &ma.s_net, sizeof(ea->aarp_spnet));
		eh->ether_type = 0;	/* if_output will treat as 802 */
	} else {
		eh->ether_type = htons(ETHERTYPE_AARP);
	}

	ea->aarp_tpnode = ea->aarp_spnode;
	ea->aarp_spnode = ma.s_node;
	ea->aarp_op = htons(AARPOP_RESPONSE);

	sa.sa_len = sizeof(struct sockaddr);
	sa.sa_family = AF_UNSPEC;
	(*ifp->if_output) (ifp, m, &sa, NULL);	/* XXX */
out:
	ifa_release(ifa, &psref);
	return;
}

static void
aarptfree(struct aarptab *aat)
{

	if (aat->aat_hold)
		m_freem(aat->aat_hold);
	aat->aat_hold = 0;
	aat->aat_timer = aat->aat_flags = 0;
	aat->aat_ataddr.s_net = 0;
	aat->aat_ataddr.s_node = 0;
}

static struct aarptab *
aarptnew(const struct at_addr *addr)
{
	int             n;
	int             oldest = -1;
	struct aarptab *aat, *aato = NULL;
	static int      first = 1;

	if (first) {
		first = 0;
		callout_init(&aarptimer_callout, 0);
		callout_reset(&aarptimer_callout, hz, aarptimer, NULL);
	}
	aat = &aarptab[AARPTAB_HASH(*addr) * AARPTAB_BSIZ];
	for (n = 0; n < AARPTAB_BSIZ; n++, aat++) {
		if (aat->aat_flags == 0)
			goto out;
		if (aat->aat_flags & ATF_PERM)
			continue;
		if ((int) aat->aat_timer > oldest) {
			oldest = aat->aat_timer;
			aato = aat;
		}
	}
	if (aato == NULL)
		return (NULL);
	aat = aato;
	aarptfree(aat);
out:
	aat->aat_ataddr = *addr;
	aat->aat_flags = ATF_INUSE;
	return (aat);
}


void
aarpprobe(void *arp)
{
	struct mbuf    *m;
	struct ether_header *eh;
	struct ether_aarp *ea;
	struct ifaddr *ia;
	struct at_ifaddr *aa;
	struct llc     *llc;
	struct sockaddr sa;
	struct ifnet   *ifp = arp;

	mutex_enter(softnet_lock);

	/*
         * We need to check whether the output ethernet type should
         * be phase 1 or 2. We have the interface that we'll be sending
         * the aarp out. We need to find an AppleTalk network on that
         * interface with the same address as we're looking for. If the
         * net is phase 2, generate an 802.2 and SNAP header.
         */
	IFADDR_READER_FOREACH(ia, ifp) {
		aa = (struct at_ifaddr *)ia;
		if (AA_SAT(aa)->sat_family == AF_APPLETALK &&
		    (aa->aa_flags & AFA_PROBING))
			break;
	}
	if (ia == NULL) {	/* serious error XXX */
		printf("aarpprobe why did this happen?!\n");
		mutex_exit(softnet_lock);
		return;
	}
	if (aa->aa_probcnt <= 0) {
		aa->aa_flags &= ~AFA_PROBING;
		wakeup(aa);
		mutex_exit(softnet_lock);
		return;
	} else {
		callout_reset(&aa->aa_probe_ch, hz / 5, aarpprobe, arp);
	}

	if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) {
		mutex_exit(softnet_lock);
		return;
	}

	MCLAIM(m, &aarp_mowner);
	m->m_len = sizeof(*ea);
	m->m_pkthdr.len = sizeof(*ea);
	m_align(m, sizeof(*ea));

	ea = mtod(m, struct ether_aarp *);
	memset(ea, 0, sizeof(*ea));

	ea->aarp_hrd = htons(AARPHRD_ETHER);
	ea->aarp_pro = htons(ETHERTYPE_ATALK);
	ea->aarp_hln = sizeof(ea->aarp_sha);
	ea->aarp_pln = sizeof(ea->aarp_spu);
	ea->aarp_op = htons(AARPOP_PROBE);
	memcpy(ea->aarp_sha, CLLADDR(ifp->if_sadl), sizeof(ea->aarp_sha));

	eh = (struct ether_header *) sa.sa_data;

	if (aa->aa_flags & AFA_PHASE2) {
		memcpy(eh->ether_dhost, atmulticastaddr,
		    sizeof(eh->ether_dhost));
		eh->ether_type = 0;	/* if_output will treat as 802 */
		M_PREPEND(m, sizeof(struct llc), M_DONTWAIT);
		if (!m) {
			mutex_exit(softnet_lock);
			return;
		}

		llc = mtod(m, struct llc *);
		llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
		llc->llc_control = LLC_UI;
		memcpy(llc->llc_org_code, aarp_org_code, sizeof(aarp_org_code));
		llc->llc_ether_type = htons(ETHERTYPE_AARP);

		memcpy(ea->aarp_spnet, &AA_SAT(aa)->sat_addr.s_net,
		      sizeof(ea->aarp_spnet));
		memcpy(ea->aarp_tpnet, &AA_SAT(aa)->sat_addr.s_net,
		      sizeof(ea->aarp_tpnet));
		ea->aarp_spnode = ea->aarp_tpnode =
		    AA_SAT(aa)->sat_addr.s_node;
	} else {
		memcpy(eh->ether_dhost, etherbroadcastaddr,
		    sizeof(eh->ether_dhost));
		eh->ether_type = htons(ETHERTYPE_AARP);
		ea->aarp_spa = ea->aarp_tpa = AA_SAT(aa)->sat_addr.s_node;
	}

#ifdef NETATALKDEBUG
	printf("aarp: sending probe for %u.%u\n",
	       ntohs(AA_SAT(aa)->sat_addr.s_net),
	       AA_SAT(aa)->sat_addr.s_node);
#endif	/* NETATALKDEBUG */

	sa.sa_len = sizeof(struct sockaddr);
	sa.sa_family = AF_UNSPEC;
	(*ifp->if_output) (ifp, m, &sa, NULL);	/* XXX */
	aa->aa_probcnt--;
	mutex_exit(softnet_lock);
}