/*      $NetBSD: link_proto.c,v 1.41 2025/06/05 06:29:27 ozaki-r Exp $  */

/*-
* Copyright (c) 1982, 1986, 1993
*      The Regents of the University of California.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*      @(#)uipc_proto.c        8.2 (Berkeley) 2/14/95
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: link_proto.c,v 1.41 2025/06/05 06:29:27 ozaki-r Exp $");

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/mbuf.h>
#include <sys/un.h>
#include <sys/socketvar.h>

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

static int sockaddr_dl_cmp(const struct sockaddr *, const struct sockaddr *);
static int link_attach(struct socket *, int);
static void link_detach(struct socket *);
static int link_accept(struct socket *, struct sockaddr *);
static int link_bind(struct socket *, struct sockaddr *, struct lwp *);
static int link_listen(struct socket *, struct lwp *);
static int link_connect(struct socket *, struct sockaddr *, struct lwp *);
static int link_connect2(struct socket *, struct socket *);
static int link_disconnect(struct socket *);
static int link_shutdown(struct socket *);
static int link_abort(struct socket *);
static int link_ioctl(struct socket *, u_long, void *, struct ifnet *);
static int link_stat(struct socket *, struct stat *);
static int link_peeraddr(struct socket *, struct sockaddr *);
static int link_sockaddr(struct socket *, struct sockaddr *);
static int link_rcvd(struct socket *, int, struct lwp *);
static int link_recvoob(struct socket *, struct mbuf *, int);
static int link_send(struct socket *, struct mbuf *, struct sockaddr *,
   struct mbuf *, struct lwp *);
static int link_sendoob(struct socket *, struct mbuf *, struct mbuf *);
static int link_purgeif(struct socket *, struct ifnet *);
static void link_init(void);

/*
* Definitions of protocols supported in the link-layer domain.
*/

DOMAIN_DEFINE(linkdomain);      /* forward define and add to link set */

static const struct pr_usrreqs link_usrreqs = {
       .pr_attach      = link_attach,
       .pr_detach      = link_detach,
       .pr_accept      = link_accept,
       .pr_bind        = link_bind,
       .pr_listen      = link_listen,
       .pr_connect     = link_connect,
       .pr_connect2    = link_connect2,
       .pr_disconnect  = link_disconnect,
       .pr_shutdown    = link_shutdown,
       .pr_abort       = link_abort,
       .pr_ioctl       = link_ioctl,
       .pr_stat        = link_stat,
       .pr_peeraddr    = link_peeraddr,
       .pr_sockaddr    = link_sockaddr,
       .pr_rcvd        = link_rcvd,
       .pr_recvoob     = link_recvoob,
       .pr_send        = link_send,
       .pr_sendoob     = link_sendoob,
       .pr_purgeif     = link_purgeif,
};

const struct protosw linksw[] = {
       {       .pr_type = SOCK_DGRAM,
               .pr_domain = &linkdomain,
               .pr_protocol = 0,       /* XXX */
               .pr_flags = PR_ATOMIC|PR_ADDR|PR_PURGEIF,
               .pr_input = NULL,
               .pr_ctlinput = NULL,
               .pr_ctloutput = NULL,
               .pr_usrreqs = &link_usrreqs,
               .pr_init = link_init,
       },
};

struct domain linkdomain = {
       .dom_family = AF_LINK,
       .dom_name = "link",
       .dom_externalize = NULL,
       .dom_dispose = NULL,
       .dom_protosw = linksw,
       .dom_protoswNPROTOSW = &linksw[__arraycount(linksw)],
       .dom_sockaddr_cmp = sockaddr_dl_cmp
};

static void
link_init(void)
{
       return;
}

static int
link_control(struct socket *so, unsigned long cmd, void *data,
   struct ifnet *ifp)
{
       int error, s;
       bool isactive, mkactive;
       struct if_laddrreq *iflr;
       union {
               struct sockaddr sa;
               struct sockaddr_dl sdl;
               struct sockaddr_storage ss;
       } u;
       struct ifaddr *ifa;
       const struct sockaddr_dl *asdl, *nsdl;
       struct psref psref;

       switch (cmd) {
       case SIOCALIFADDR:
       case SIOCDLIFADDR:
       case SIOCGLIFADDR:
               iflr = data;

               if (iflr->addr.ss_family != AF_LINK)
                       return EINVAL;

               asdl = satocsdl(sstocsa(&iflr->addr));

               if (asdl->sdl_alen != ifp->if_addrlen)
                       return EINVAL;

               if (sockaddr_dl_init(&u.sdl, sizeof(u.ss), ifp->if_index,
                   ifp->if_type, ifp->if_xname, strlen(ifp->if_xname),
                   CLLADDR(asdl), asdl->sdl_alen) == NULL)
                       return EINVAL;

               if ((iflr->flags & IFLR_PREFIX) == 0)
                       ;
               else if (iflr->prefixlen != NBBY * ifp->if_addrlen)
                       return EINVAL;  /* XXX match with prefix */

               error = 0;

               s = pserialize_read_enter();
               IFADDR_READER_FOREACH(ifa, ifp) {
                       if (sockaddr_cmp(&u.sa, ifa->ifa_addr) == 0) {
                               ifa_acquire(ifa, &psref);
                               break;
                       }
               }
               pserialize_read_exit(s);

               switch (cmd) {
               case SIOCGLIFADDR:
                       ifa_release(ifa, &psref);
                       s = pserialize_read_enter();
                       if ((iflr->flags & IFLR_PREFIX) == 0)
                               ifa = if_first_addr(ifp, AF_LINK);
                       if (ifa == NULL) {
                               pserialize_read_exit(s);
                               error = EADDRNOTAVAIL;
                               break;
                       }

                       if (ifa == ifp->if_dl)
                               iflr->flags = IFLR_ACTIVE;
                       else
                               iflr->flags = 0;

                       if (ifa == ifp->if_hwdl)
                               iflr->flags |= IFLR_FACTORY;

                       sockaddr_copy(sstosa(&iflr->addr), sizeof(iflr->addr),
                           ifa->ifa_addr);
                       pserialize_read_exit(s);
                       ifa = NULL;

                       break;
               case SIOCDLIFADDR:
                       if (ifa == NULL)
                               error = EADDRNOTAVAIL;
                       else if (ifa == ifp->if_dl || ifa == ifp->if_hwdl)
                               error = EBUSY;
                       else {
                               /* TBD routing socket */
                               rt_addrmsg(RTM_DELETE, ifa);
                               /* We need to release psref for ifa_remove */
                               ifaref(ifa);
                               ifa_release(ifa, &psref);
                               ifa_remove(ifp, ifa);
                               KASSERTMSG(ifa->ifa_refcnt == 1, "ifa_refcnt=%d",
                                   ifa->ifa_refcnt);
                               ifafree(ifa);
                               ifa = NULL;
                       }
                       break;
               case SIOCALIFADDR:
                       if (ifa == NULL) {
                               ifa = if_dl_create(ifp, &nsdl);
                               if (ifa == NULL) {
                                       error = ENOMEM;
                                       break;
                               }
                               ifa_acquire(ifa, &psref);
                               sockaddr_copy(ifa->ifa_addr,
                                   ifa->ifa_addr->sa_len, &u.sa);
                               ifa_insert(ifp, ifa);
                               rt_addrmsg(RTM_ADD, ifa);
                       }

                       mkactive = (iflr->flags & IFLR_ACTIVE) != 0;
                       isactive = (ifa == ifp->if_dl);

                       if (!isactive && mkactive) {
                               if_activate_sadl(ifp, ifa, nsdl);
                               rt_addrmsg(RTM_CHANGE, ifa);
                               error = ENETRESET;
                       }
                       break;
               }
               ifa_release(ifa, &psref);
               if (error != ENETRESET)
                       return error;
               else if ((ifp->if_flags & IFF_RUNNING) != 0 &&
                        ifp->if_init != NULL)
                       return if_init(ifp);
               else
                       return 0;
       default:
               return ENOTTY;
       }
}

static int
link_attach(struct socket *so, int proto)
{
       sosetlock(so);
       KASSERT(solocked(so));
       return 0;
}

static void
link_detach(struct socket *so)
{
       KASSERT(solocked(so));
       sofree(so);
}

static int
link_accept(struct socket *so, struct sockaddr *nam)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_bind(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_listen(struct socket *so, struct lwp *l)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_connect(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_connect2(struct socket *so, struct socket *so2)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_disconnect(struct socket *so)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_shutdown(struct socket *so)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_abort(struct socket *so)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_ioctl(struct socket *so, u_long cmd, void *nam, struct ifnet *ifp)
{
       return link_control(so, cmd, nam, ifp);
}

static int
link_stat(struct socket *so, struct stat *ub)
{
       KASSERT(solocked(so));

       return 0;
}

static int
link_peeraddr(struct socket *so, struct sockaddr *nam)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_sockaddr(struct socket *so, struct sockaddr *nam)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_rcvd(struct socket *so, int flags, struct lwp *l)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_recvoob(struct socket *so, struct mbuf *m, int flags)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_send(struct socket *so, struct mbuf *m, struct sockaddr *nam,
   struct mbuf *control, struct lwp *l)
{
       KASSERT(solocked(so));

       return EOPNOTSUPP;
}

static int
link_sendoob(struct socket *so, struct mbuf *m, struct mbuf *control)
{
       KASSERT(solocked(so));

       m_freem(m);
       m_freem(control);

       return EOPNOTSUPP;
}

static int
link_purgeif(struct socket *so, struct ifnet *ifp)
{

       return EOPNOTSUPP;
}

/* Compare the field at byte offsets [fieldstart, fieldend) in
* two memory regions, [l, l + llen) and [r, r + llen).
*/
static inline int
submemcmp(const void *l, const void *r,
   const uint_fast8_t llen, const uint_fast8_t rlen,
   const uint_fast8_t fieldstart, const uint_fast8_t fieldend)
{
       uint_fast8_t cmpend, minlen;
       const uint8_t *lb = l, *rb = r;
       int rc;

       minlen = MIN(llen, rlen);

       /* The field is missing from one region.  The shorter region is the
        * lesser region.
        */
       if (fieldstart >= minlen)
               return llen - rlen;

       /* Two empty, present fields are always equal. */
       if (fieldstart > fieldend)
               return 0;

       cmpend = MIN(fieldend, minlen);

       rc = memcmp(&lb[fieldstart], &rb[fieldstart], cmpend - fieldstart);

       if (rc != 0)
               return rc;
       /* If one or both fields are truncated, then the shorter is the lesser
        * field.
        */
       if (minlen < fieldend)
               return llen - rlen;
       /* Fields are full-length and equal.  The fields are equal. */
       return 0;
}

uint8_t
sockaddr_dl_measure(uint8_t namelen, uint8_t addrlen)
{
       return offsetof(struct sockaddr_dl, sdl_data[namelen + addrlen]);
}

struct sockaddr *
sockaddr_dl_alloc(uint16_t ifindex, uint8_t type,
   const void *name, uint8_t namelen, const void *addr, uint8_t addrlen,
   int flags)
{
       struct sockaddr *sa;
       socklen_t len;

       len = sockaddr_dl_measure(namelen, addrlen);
       sa = sockaddr_alloc(AF_LINK, len, flags);

       if (sa == NULL)
               return NULL;

       if (sockaddr_dl_init(satosdl(sa), len, ifindex, type, name, namelen,
           addr, addrlen) == NULL) {
               sockaddr_free(sa);
               return NULL;
       }

       return sa;
}

struct sockaddr_dl *
sockaddr_dl_init(struct sockaddr_dl *sdl, socklen_t socklen, uint16_t ifindex,
   uint8_t type, const void *name, uint8_t namelen, const void *addr,
   uint8_t addrlen)
{
       socklen_t len;

       sdl->sdl_family = AF_LINK;
       sdl->sdl_slen = 0;
       len = sockaddr_dl_measure(namelen, addrlen);
       if (len > socklen) {
               sdl->sdl_len = socklen;
#ifdef DIAGNOSTIC
               printf("%s: too long: %u > %u\n", __func__, (u_int)len,
                   (u_int)socklen);
#endif
               return NULL;
       }
       sdl->sdl_len = len;
       sdl->sdl_index = ifindex;
       sdl->sdl_type = type;
       memset(&sdl->sdl_data[0], 0, namelen + addrlen);
       if (name != NULL) {
               memcpy(&sdl->sdl_data[0], name, namelen);
               sdl->sdl_nlen = namelen;
       } else
               sdl->sdl_nlen = 0;
       if (addr != NULL) {
               memcpy(&sdl->sdl_data[sdl->sdl_nlen], addr, addrlen);
               sdl->sdl_alen = addrlen;
       } else
               sdl->sdl_alen = 0;
       return sdl;
}

static int
sockaddr_dl_cmp(const struct sockaddr *sa1, const struct sockaddr *sa2)
{
       int rc;
       const uint_fast8_t indexofs = offsetof(struct sockaddr_dl, sdl_index);
       const uint_fast8_t nlenofs = offsetof(struct sockaddr_dl, sdl_nlen);
       uint_fast8_t dataofs = offsetof(struct sockaddr_dl, sdl_data[0]);
       const struct sockaddr_dl *sdl1, *sdl2;

       sdl1 = satocsdl(sa1);
       sdl2 = satocsdl(sa2);

       rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
           indexofs, nlenofs);

       if (rc != 0)
               return rc;

       rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
           dataofs, dataofs + MIN(sdl1->sdl_nlen, sdl2->sdl_nlen));

       if (rc != 0)
               return rc;

       if (sdl1->sdl_nlen != sdl2->sdl_nlen)
               return sdl1->sdl_nlen - sdl2->sdl_nlen;

       dataofs += sdl1->sdl_nlen;

       rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
           dataofs, dataofs + MIN(sdl1->sdl_alen, sdl2->sdl_alen));

       if (rc != 0)
               return rc;

       if (sdl1->sdl_alen != sdl2->sdl_alen)
               return sdl1->sdl_alen - sdl2->sdl_alen;

       dataofs += sdl1->sdl_alen;

       rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
           dataofs, dataofs + MIN(sdl1->sdl_slen, sdl2->sdl_slen));

       if (sdl1->sdl_slen != sdl2->sdl_slen)
               return sdl1->sdl_slen - sdl2->sdl_slen;

       return sdl1->sdl_len - sdl2->sdl_len;
}

struct sockaddr_dl *
sockaddr_dl_setaddr(struct sockaddr_dl *sdl, socklen_t socklen,
   const void *addr, uint8_t addrlen)
{
       socklen_t len;

       len = sockaddr_dl_measure(sdl->sdl_nlen, addrlen);
       if (len > socklen) {
#ifdef DIAGNOSTIC
               printf("%s: too long: %u > %u\n", __func__, (u_int)len,
                   (u_int)socklen);
#endif
               return NULL;
       }
       memcpy(&sdl->sdl_data[sdl->sdl_nlen], addr, addrlen);
       sdl->sdl_alen = addrlen;
       sdl->sdl_len = len;
       return sdl;
}

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