/*-
 * Copyright (c) 2009-2020 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This material is based upon work partially supported by The
 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * NPF network buffer management interface.
 *
 * Network buffer in NetBSD is mbuf.  Internal mbuf structures are
 * abstracted within this source.
 */

#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: npf_mbuf.c,v 1.25 2023/02/12 13:38:37 kardel Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>
#include <netinet/in_offload.h>
#endif

#include "npf_impl.h"

#ifdef _KERNEL
#ifdef INET6
#include <netinet6/in6.h>
#include <netinet6/in6_offload.h>
#endif
#endif

#if defined(_NPF_STANDALONE)
#define m_length(m)             (nbuf)->nb_mops->getchainlen(m)
#define m_buflen(m)             (nbuf)->nb_mops->getlen(m)
#define m_next_ptr(m)           (nbuf)->nb_mops->getnext(m)
#define m_ensure_contig(m,t)    (nbuf)->nb_mops->ensure_contig((m), (t))
#define m_makewritable(m,o,l,f) (nbuf)->nb_mops->ensure_writable((m), (o+l))
#define mtod(m,t)               ((t)((nbuf)->nb_mops->getdata(m)))
#define m_flags_p(m,f)          true
#define M_UNWRITABLE(m, l)      false
#else
#define m_next_ptr(m)           (m)->m_next
#define m_buflen(m)             ((size_t)(m)->m_len)
#define m_flags_p(m,f)          (((m)->m_flags & (f)) != 0)
#endif

#define NBUF_ENSURE_ALIGN       (MAX(COHERENCY_UNIT, 64))
#define NBUF_ENSURE_MASK        (NBUF_ENSURE_ALIGN - 1)
#define NBUF_ENSURE_ROUNDUP(x)  (((x) + NBUF_ENSURE_ALIGN) & ~NBUF_ENSURE_MASK)

void
nbuf_init(npf_t *npf, nbuf_t *nbuf, struct mbuf *m, const ifnet_t *ifp)
{
        unsigned ifid = npf_ifmap_getid(npf, ifp);

        KASSERT(m_flags_p(m, M_PKTHDR));
        nbuf->nb_mops = npf->mbufops;

        nbuf->nb_mbuf0 = m;
        nbuf->nb_ifp = ifp;
        nbuf->nb_ifid = ifid;
        nbuf_reset(nbuf);
}

void
nbuf_reset(nbuf_t *nbuf)
{
        struct mbuf *m = nbuf->nb_mbuf0;

        nbuf->nb_mbuf = m;
        nbuf->nb_nptr = mtod(m, void *);
}

void *
nbuf_dataptr(nbuf_t *nbuf)
{
        KASSERT(nbuf->nb_nptr);
        return nbuf->nb_nptr;
}

size_t
nbuf_offset(const nbuf_t *nbuf)
{
        const struct mbuf *m = nbuf->nb_mbuf;
        const unsigned off = (uintptr_t)nbuf->nb_nptr - mtod(m, uintptr_t);
        const int poff = m_length(nbuf->nb_mbuf0) - m_length(m) + off;

        return poff;
}

struct mbuf *
nbuf_head_mbuf(nbuf_t *nbuf)
{
        return nbuf->nb_mbuf0;
}

bool
nbuf_flag_p(const nbuf_t *nbuf, int flag)
{
        return (nbuf->nb_flags & flag) != 0;
}

void
nbuf_unset_flag(nbuf_t *nbuf, int flag)
{
        nbuf->nb_flags &= ~flag;
}

/*
 * nbuf_advance: advance in nbuf or chain by specified amount of bytes and,
 * if requested, ensure that the area *after* advance is contiguous.
 *
 * => Returns new pointer to data in nbuf or NULL if offset is invalid.
 * => Current nbuf and the offset is stored in the nbuf metadata.
 */
void *
nbuf_advance(nbuf_t *nbuf, size_t len, size_t ensure)
{
        struct mbuf *m = nbuf->nb_mbuf;
        unsigned off, wmark;
        uint8_t *d;

        /* Offset with amount to advance. */
        off = (uintptr_t)nbuf->nb_nptr - mtod(m, uintptr_t) + len;
        wmark = m_buflen(m);

        /* Find the mbuf according to offset. */
        while (__predict_false(wmark <= off)) {
                m = m_next_ptr(m);
                if (__predict_false(m == NULL)) {
                        /*
                         * If end of the chain, then the offset is
                         * higher than packet length.
                         */
                        return NULL;
                }
                wmark += m_buflen(m);
        }
        KASSERT(off < m_length(nbuf->nb_mbuf0));

        /* Offset in mbuf data. */
        d = mtod(m, uint8_t *);
        KASSERT(off >= (wmark - m_buflen(m)));
        d += (off - (wmark - m_buflen(m)));

        nbuf->nb_mbuf = m;
        nbuf->nb_nptr = d;

        if (ensure) {
                /* Ensure contiguousness (may change nbuf chain). */
                d = nbuf_ensure_contig(nbuf, ensure);
        }
        return d;
}

/*
 * nbuf_ensure_contig: check whether the specified length from the current
 * point in the nbuf is contiguous.  If not, rearrange the chain to be so.
 *
 * => Returns pointer to the data at the current offset in the buffer.
 * => Returns NULL on failure and nbuf becomes invalid.
 */
void *
nbuf_ensure_contig(nbuf_t *nbuf, size_t len)
{
        const struct mbuf * const n = nbuf->nb_mbuf;
        const size_t off = (uintptr_t)nbuf->nb_nptr - mtod(n, uintptr_t);

        KASSERT(off <= m_buflen(n));

        if (__predict_false(m_buflen(n) < (off + len))) {
                struct mbuf *m = nbuf->nb_mbuf0;
                const size_t foff = nbuf_offset(nbuf);
                const size_t plen = m_length(m);
                const size_t mlen = m_buflen(m);
                size_t target;
                bool success;

                //npf_stats_inc(npf, NPF_STAT_NBUF_NONCONTIG);

                /* Attempt to round-up to NBUF_ENSURE_ALIGN bytes. */
                if ((target = NBUF_ENSURE_ROUNDUP(foff + len)) > plen) {
                        target = foff + len;
                }

                /* Rearrange the chain to be contiguous. */
                KASSERT(m_flags_p(m, M_PKTHDR));
                success = m_ensure_contig(&m, target);
                KASSERT(m != NULL);

                /* If no change in the chain: return what we have. */
                if (m == nbuf->nb_mbuf0 && m_buflen(m) == mlen) {
                        return success ? nbuf->nb_nptr : NULL;
                }

                /*
                 * The mbuf chain was re-arranged.  Update the pointers
                 * accordingly and indicate that the references to the data
                 * might need a reset.
                 */
                KASSERT(m_flags_p(m, M_PKTHDR));
                nbuf->nb_mbuf0 = m;
                nbuf->nb_mbuf = m;

                KASSERT(foff < m_buflen(m) && foff < m_length(m));
                nbuf->nb_nptr = mtod(m, uint8_t *) + foff;
                nbuf->nb_flags |= NBUF_DATAREF_RESET;

                if (!success) {
                        //npf_stats_inc(npf, NPF_STAT_NBUF_CONTIG_FAIL);
                        return NULL;
                }
        }
        return nbuf->nb_nptr;
}

void *
nbuf_ensure_writable(nbuf_t *nbuf, size_t len)
{
        struct mbuf *m = nbuf->nb_mbuf;
        const unsigned off = (uintptr_t)nbuf->nb_nptr - mtod(m, uintptr_t);
        const int tlen = off + len;
        bool head_buf;

        KASSERT(off < m_length(nbuf->nb_mbuf0));

        if (!M_UNWRITABLE(m, tlen)) {
                return nbuf->nb_nptr;
        }
        head_buf = (nbuf->nb_mbuf0 == m);
        if (m_makewritable(&m, 0, tlen, M_NOWAIT)) {
                memset(nbuf, 0, sizeof(nbuf_t));
                return NULL;
        }
        if (head_buf) {
                KASSERT(m_flags_p(m, M_PKTHDR));
                KASSERT(off < m_length(m));
                nbuf->nb_mbuf0 = m;
        }
        nbuf->nb_mbuf = m;
        nbuf->nb_nptr = mtod(m, uint8_t *) + off;

        return nbuf->nb_nptr;
}

bool
nbuf_cksum_barrier(nbuf_t *nbuf, int di)
{
#ifdef _KERNEL
        struct mbuf *m;

        if (di != PFIL_OUT) {
                return false;
        }
        m = nbuf->nb_mbuf0;
        KASSERT(m_flags_p(m, M_PKTHDR));

        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4 | M_CSUM_UDPv4)) {
                in_undefer_cksum_tcpudp(m);
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4 | M_CSUM_UDPv4);
                return true;
        }
#ifdef INET6
        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv6 | M_CSUM_UDPv6)) {
                in6_undefer_cksum_tcpudp(m);
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv6 | M_CSUM_UDPv6);
                return true;
        }
#endif
#else
        (void)nbuf; (void)di;
#endif
        return false;
}

/*
 * npf_mbuf_add_tag: associate a tag with the network buffer.
 *
 * => Returns 0 on success or error number on failure.
 */
int
npf_mbuf_add_tag(nbuf_t *nbuf, struct mbuf *m, uint32_t val)
{
#ifdef _KERNEL
        struct m_tag *mt;
        uint32_t *dat;

        KASSERT(m_flags_p(m, M_PKTHDR));

        mt = m_tag_get(PACKET_TAG_NPF, sizeof(uint32_t), M_NOWAIT);
        if (mt == NULL) {
                return ENOMEM;
        }
        dat = (uint32_t *)(mt + 1);
        *dat = val;
        m_tag_prepend(m, mt);
        return 0;
#else
        if (!nbuf->nb_mops->set_tag) {
                return ENOTSUP;
        }
        return nbuf->nb_mops->set_tag(m, val);
#endif
}

/*
 * nbuf_add_tag: associate a tag with the network buffer.
 *
 * => Returns 0 on success or error number on failure.
 */
int
nbuf_add_tag(nbuf_t *nbuf, uint32_t val)
{
        struct mbuf *m = nbuf->nb_mbuf0;
        return npf_mbuf_add_tag(nbuf, m, val);
}

/*
 * nbuf_find_tag: find a tag associated with a network buffer.
 *
 * => Returns 0 on success or error number on failure.
 */
int
nbuf_find_tag(nbuf_t *nbuf, uint32_t *val)
{
        struct mbuf *m = nbuf->nb_mbuf0;
#ifdef _KERNEL
        struct m_tag *mt;

        KASSERT(m_flags_p(m, M_PKTHDR));

        mt = m_tag_find(m, PACKET_TAG_NPF);
        if (mt == NULL) {
                return EINVAL;
        }
        *val = *(uint32_t *)(mt + 1);
        return 0;
#else
        if (!nbuf->nb_mops->get_tag) {
                return ENOTSUP;
        }
        return nbuf->nb_mops->get_tag(m, val);
#endif
}