/*-
 * 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.
 *
 *	Research Systems Unix Group
 *	The University of Michigan
 *	c/o Mike Clark
 *	535 W. William Street
 *	Ann Arbor, Michigan
 *	+1-313-763-0525
 *	netatalk@itd.umich.edu
 */

/* $FreeBSD: src/sys/netatalk/ddp_output.c,v 1.28 2005/08/30 16:28:46 andre Exp $ */

#include "opt_mac.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>

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

#undef s_net

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

int	ddp_cksum = 1;

int
ddp_output(struct mbuf *m, struct socket *so)
{
    struct ddpehdr	*deh;
    struct ddpcb *ddp = sotoddpcb(so);

#ifdef MAC
    SOCK_LOCK(so);
    mac_create_mbuf_from_socket(so, m);
    SOCK_UNLOCK(so);
#endif

    M_PREPEND(m, sizeof(struct ddpehdr), M_DONTWAIT);
    if (m == NULL)
	return (ENOBUFS);

    deh = mtod(m, struct ddpehdr *);
    deh->deh_pad = 0;
    deh->deh_hops = 0;

    deh->deh_len = m->m_pkthdr.len;

    deh->deh_dnet = ddp->ddp_fsat.sat_addr.s_net;
    deh->deh_dnode = ddp->ddp_fsat.sat_addr.s_node;
    deh->deh_dport = ddp->ddp_fsat.sat_port;
    deh->deh_snet = ddp->ddp_lsat.sat_addr.s_net;
    deh->deh_snode = ddp->ddp_lsat.sat_addr.s_node;
    deh->deh_sport = ddp->ddp_lsat.sat_port;

    /*
     * The checksum calculation is done after all of the other bytes have
     * been filled in.
     */
    if (ddp_cksum) {
	deh->deh_sum = at_cksum(m, sizeof(int));
    } else {
	deh->deh_sum = 0;
    }
    deh->deh_bytes = htonl(deh->deh_bytes);

#ifdef NETATALK_DEBUG
    printf ("ddp_output: from %d.%d:%d to %d.%d:%d\n",
	ntohs(deh->deh_snet), deh->deh_snode, deh->deh_sport,
	ntohs(deh->deh_dnet), deh->deh_dnode, deh->deh_dport);
#endif
    return (ddp_route(m, &ddp->ddp_route));
}

u_short
at_cksum(struct mbuf *m, int skip)
{
    u_char	*data, *end;
    u_long	cksum = 0;

    for (; m; m = m->m_next) {
	for (data = mtod(m, u_char *), end = data + m->m_len; data < end;
		data++) {
	    if (skip) {
		skip--;
		continue;
	    }
	    cksum = (cksum + *data) << 1;
	    if (cksum & 0x00010000) {
		cksum++;
	    }
	    cksum &= 0x0000ffff;
	}
    }

    if (cksum == 0) {
	cksum = 0x0000ffff;
    }
    return ((u_short)cksum);
}

int
ddp_route(struct mbuf *m, struct route *ro)
{
    struct sockaddr_at	gate;
    struct elaphdr	*elh;
    struct mbuf		*m0;
    struct at_ifaddr	*aa = NULL;
    struct ifnet	*ifp = NULL;
    u_short		net;

#if 0
    /* Check for net zero, node zero ("myself") */
    if (satosat(&ro->ro_dst)->sat_addr.s_net == ATADDR_ANYNET
        && satosat(&ro->ro_dst)->sat_addr.s_node == ATADDR_ANYNODE) {
	    /* Find the loopback interface */
    }
#endif

    /*
     * if we have a route, find the ifa that refers to this route.
     * I.e The ifa used to get to the gateway.
     */
    if ((ro->ro_rt == NULL)
    || (ro->ro_rt->rt_ifa == NULL)
    || ((ifp = ro->ro_rt->rt_ifa->ifa_ifp) == NULL)) {
	rtalloc(ro);
    }
    if ((ro->ro_rt != NULL)
    && (ro->ro_rt->rt_ifa)
    && (ifp = ro->ro_rt->rt_ifa->ifa_ifp)) {
	net = ntohs(satosat(ro->ro_rt->rt_gateway)->sat_addr.s_net);
	for (aa = at_ifaddr_list; aa != NULL; aa = aa->aa_next) {
	    if (((net == 0) || (aa->aa_ifp == ifp)) &&
		    net >= ntohs(aa->aa_firstnet) &&
		    net <= ntohs(aa->aa_lastnet)) {
		break;
	    }
	}
    } else {
	m_freem(m);
#ifdef NETATALK_DEBUG
	if (ro->ro_rt == NULL)
	    printf ("ddp_route: no ro_rt.\n");
	else if (ro->ro_rt->rt_ifa == NULL)
	    printf ("ddp_route: no ro_rt->rt_ifa\n");
	else
	    printf ("ddp_route: no ro_rt->rt_ifa->ifa_ifp\n");
#endif
	return (ENETUNREACH);
    }

    if (aa == NULL) {
#ifdef NETATALK_DEBUG
	printf("ddp_route: no atalk address found for %s\n", 
	    ifp->if_xname);
#endif
	m_freem(m);
	return (ENETUNREACH);
    }

    /*
     * if the destination address is on a directly attached node use that,
     * else use the official gateway.
     */
    if (ntohs(satosat(&ro->ro_dst)->sat_addr.s_net) >=
	    ntohs(aa->aa_firstnet) &&
	    ntohs(satosat(&ro->ro_dst)->sat_addr.s_net) <=
	    ntohs(aa->aa_lastnet)) {
	gate = *satosat(&ro->ro_dst);
    } else {
	gate = *satosat(ro->ro_rt->rt_gateway);
    }

    /*
     * There are several places in the kernel where data is added to
     * an mbuf without ensuring that the mbuf pointer is aligned.
     * This is bad for transition routing, since phase 1 and phase 2
     * packets end up poorly aligned due to the three byte elap header.
     */
    if (!(aa->aa_flags & AFA_PHASE2)) {
	MGET(m0, M_DONTWAIT, MT_DATA);
	if (m0 == NULL) {
	    m_freem(m);
	    printf("ddp_route: no buffers\n");
	    return (ENOBUFS);
	}
#ifdef MAC
	mac_copy_mbuf(m, m0);
#endif
	m0->m_next = m;
	/* XXX perhaps we ought to align the header? */
	m0->m_len = SZ_ELAPHDR;
	m = m0;

	elh = mtod(m, struct elaphdr *);
	elh->el_snode = satosat(&aa->aa_addr)->sat_addr.s_node;
	elh->el_type = ELAP_DDPEXTEND;
	elh->el_dnode = gate.sat_addr.s_node;
    }
    ro->ro_rt->rt_use++;

#ifdef NETATALK_DEBUG
    printf ("ddp_route: from %d.%d to %d.%d, via %d.%d (%s)\n",
	ntohs(satosat(&aa->aa_addr)->sat_addr.s_net),
	satosat(&aa->aa_addr)->sat_addr.s_node,
	ntohs(satosat(&ro->ro_dst)->sat_addr.s_net),
	satosat(&ro->ro_dst)->sat_addr.s_node,
	ntohs(gate.sat_addr.s_net),
	gate.sat_addr.s_node,
	ifp->if_xname);
#endif

    /* short-circuit the output if we're sending this to ourself */
    if ((satosat(&aa->aa_addr)->sat_addr.s_net  == satosat(&ro->ro_dst)->sat_addr.s_net) &&
	(satosat(&aa->aa_addr)->sat_addr.s_node == satosat(&ro->ro_dst)->sat_addr.s_node))
    {
	return (if_simloop(ifp, m, gate.sat_family, 0));
    }

    return ((*ifp->if_output)(ifp,
	m, (struct sockaddr *)&gate, NULL)); /* XXX */
}
