/*      $NetBSD: ddp_output.c,v 1.22 2023/03/30 17:48:10 riastradh 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
*      [email protected]
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ddp_output.c,v 1.22 2023/03/30 17:48:10 riastradh Exp $");
#include "opt_atalk.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/syslog.h>

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

#include <netinet/in.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 ddpcb *ddp)
{
       struct ddpehdr *deh;

       M_PREPEND(m, sizeof(struct ddpehdr), M_DONTWAIT);
       if (!m)
               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);

       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 rtentry *rt;
       struct sockaddr_at gate;
       struct elaphdr *elh;
       struct at_ifaddr *aa = NULL;
       struct ifnet   *ifp = NULL;
       uint16_t        net;
       uint8_t         loopback = 0;
       int             error;

       if ((rt = rtcache_validate(ro)) != NULL && (ifp = rt->rt_ifp) != NULL) {
               const struct sockaddr_at *dst = satocsat(rtcache_getdst(ro));
               uint16_t dnet = dst->sat_addr.s_net;
               uint8_t dnode = dst->sat_addr.s_node;
               net = satosat(rt->rt_gateway)->sat_addr.s_net;

               TAILQ_FOREACH(aa, &at_ifaddr, aa_list) {
                       if (ntohs(net) >= ntohs(aa->aa_firstnet) &&
                           ntohs(net) <= ntohs(aa->aa_lastnet)) {
                               /* Are we talking to ourselves? */
                               if (dnet == aa->aa_addr.sat_addr.s_net &&
                                   dnode == aa->aa_addr.sat_addr.s_node) {
                                       /* If to us, redirect to lo0. */
                                       ifp = lo0ifp;
                               }
                               /* Or is it a broadcast? */
                               else if (dnet == aa->aa_addr.sat_addr.s_net &&
                                       dnode == 255) {
                                       /* If broadcast, loop back a copy. */
                                       loopback = 1;
                               }
                               break;
                       }
               }
       }
       if (aa == NULL) {
#ifdef NETATALKDEBUG
               printf("%s: no address found\n", __func__);
#endif
               m_freem(m);
               error = EINVAL;
               goto out;
       }
       /*
        * 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)) {
               M_PREPEND(m, SZ_ELAPHDR, M_DONTWAIT);
               if (m == NULL) {
                       error = ENOBUFS;
                       goto out;
               }

               elh = mtod(m, struct elaphdr *);
               elh->el_snode = aa->aa_addr.sat_addr.s_node;
               elh->el_type = ELAP_DDPEXTEND;
               if (ntohs(satocsat(rtcache_getdst(ro))->sat_addr.s_net) >=
                   ntohs(aa->aa_firstnet) &&
                   ntohs(satocsat(rtcache_getdst(ro))->sat_addr.s_net) <=
                   ntohs(aa->aa_lastnet)) {
                       elh->el_dnode =
                           satocsat(rtcache_getdst(ro))->sat_addr.s_node;
               } else {
                       elh->el_dnode =
                           satosat(rt->rt_gateway)->sat_addr.s_node;
               }
       }
       if (ntohs(satocsat(rtcache_getdst(ro))->sat_addr.s_net) >=
           ntohs(aa->aa_firstnet) &&
           ntohs(satocsat(rtcache_getdst(ro))->sat_addr.s_net) <=
           ntohs(aa->aa_lastnet)) {
               gate = *satocsat(rtcache_getdst(ro));
       } else {
               gate = *satosat(rt->rt_gateway);
       }
       rt->rt_use++;

#if IFA_STATS
       aa->aa_ifa.ifa_data.ifad_outbytes += m->m_pkthdr.len;
#endif

       /* XXX */
       if (loopback && rtcache_getdst(ro)->sa_family == AF_APPLETALK) {
               struct mbuf *copym = m_copypacket(m, M_DONTWAIT);

#ifdef NETATALKDEBUG
               printf("Looping back (not AARP).\n");
#endif
               looutput(lo0ifp, copym, rtcache_getdst(ro), NULL);
       }

       error = if_output_lock(ifp, ifp, m, (struct sockaddr *)&gate, NULL);
out:
       rtcache_unref(rt, ro);
       return error;
}

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