/*
 * Copyright (C) 2011 Matteo Landi, Luigi Rizzo. All rights reserved.
 * Copyright (C) 2013 Universita` di Pisa
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

/*
 * $FreeBSD$
 *
 * This header contains the macros used to manipulate netmap structures
 * and packets in userspace. See netmap(4) for more information.
 *
 * The address of the struct netmap_if, say nifp, is computed from the
 * value returned from ioctl(.., NIOCREG, ...) and the mmap region:
 *      ioctl(fd, NIOCREG, &req);
 *      mem = mmap(0, ... );
 *      nifp = NETMAP_IF(mem, req.nr_nifp);
 *              (so simple, we could just do it manually)
 *
 * From there:
 *      struct netmap_ring *NETMAP_TXRING(nifp, index)
 *      struct netmap_ring *NETMAP_RXRING(nifp, index)
 *              we can access ring->nr_cur, ring->nr_avail, ring->nr_flags
 *
 *      ring->slot[i] gives us the i-th slot (we can access
 *              directly plen, flags, bufindex)
 *
 *      char *buf = NETMAP_BUF(ring, x) returns a pointer to
 *              the buffer numbered x
 *
 * Since rings are circular, we have macros to compute the next index
 *      i = NETMAP_RING_NEXT(ring, i);
 *
 * To ease porting apps from pcap to netmap we supply a few fuctions
 * that can be called to open, close and read from netmap in a way
 * similar to libpcap.
 *
 * In order to use these, include #define NETMAP_WITH_LIBS
 * in the source file that invokes these functions.
 */

#ifndef _NET_NETMAP_USER_H_
#define _NET_NETMAP_USER_H_

#include <stdint.h>
#include <net/if.h>             /* IFNAMSIZ */
#include <net/netmap/netmap.h>

#define _NETMAP_OFFSET(type, ptr, offset) \
        ((type)(void *)((char *)(ptr) + (offset)))

#define NETMAP_IF(b, o) _NETMAP_OFFSET(struct netmap_if *, b, o)

#define NETMAP_TXRING(nifp, index) _NETMAP_OFFSET(struct netmap_ring *, \
        nifp, (nifp)->ring_ofs[index] )

#define NETMAP_RXRING(nifp, index) _NETMAP_OFFSET(struct netmap_ring *, \
        nifp, (nifp)->ring_ofs[index + (nifp)->ni_tx_rings + 1] )

#define NETMAP_BUF(ring, index)                         \
        ((char *)(ring) + (ring)->buf_ofs + ((index)*(ring)->nr_buf_size))

#define NETMAP_BUF_IDX(ring, buf)                       \
        ( ((char *)(buf) - ((char *)(ring) + (ring)->buf_ofs) ) / \
                (ring)->nr_buf_size )

#define NETMAP_RING_NEXT(r, i)                          \
        ((i)+1 == (r)->num_slots ? 0 : (i) + 1 )

#define NETMAP_RING_FIRST_RESERVED(r)                   \
        ( (r)->cur < (r)->reserved ?                    \
          (r)->cur + (r)->num_slots - (r)->reserved :   \
          (r)->cur - (r)->reserved )

/*
 * Return 1 if the given tx ring is empty.
 */
#define NETMAP_TX_RING_EMPTY(r) ((r)->avail >= (r)->num_slots - 1)

#ifdef NETMAP_WITH_LIBS
/*
 * Support for simple I/O libraries.
 * Include other system headers required for compiling this.
 */

#ifndef HAVE_NETMAP_WITH_LIBS
#define HAVE_NETMAP_WITH_LIBS

#include <sys/time.h>
#include <sys/mman.h>
#include <string.h>     /* memset */
#include <sys/ioctl.h>
#include <sys/errno.h>  /* EINVAL */
#include <fcntl.h>      /* O_RDWR */
#include <stdlib.h>

struct nm_hdr_t {       /* same as pcap_pkthdr */
        struct timeval  ts;
        uint32_t        caplen;
        uint32_t        len;
};

struct nm_desc_t {
        struct nm_desc_t *self;
        int fd;
        void *mem;
        int memsize;
        struct netmap_if *nifp;
        uint16_t first_ring, last_ring, cur_ring;
        struct nmreq req;
        struct nm_hdr_t hdr;
};

/*
 * when the descriptor is open correctly, d->self == d
 */
#define P2NMD(p)                ((struct nm_desc_t *)(p))
#define IS_NETMAP_DESC(d)       (P2NMD(d)->self == P2NMD(d))
#define NETMAP_FD(d)            (P2NMD(d)->fd)

/*
 * The callback, invoked on each received packet. Same as libpcap
 */
typedef void (*nm_cb_t)(u_char *, const struct nm_hdr_t *, const u_char *d);

/*
 * The open routine accepts an ifname (netmap:foo or vale:foo) and
 * optionally a second (string) argument indicating the ring number
 * to open. If successful, t opens the fd and maps the memory.
 */
static struct nm_desc_t *nm_open(const char *ifname,
         const char *ring_no, int flags, int ring_flags);

/*
 * nm_dispatch() is the same as pcap_dispatch()
 * nm_next() is the same as pcap_next()
 */
static int nm_dispatch(struct nm_desc_t *, int, nm_cb_t, u_char *);
static u_char *nm_next(struct nm_desc_t *, struct nm_hdr_t *);

/*
 * unmap memory, close file descriptor and free the descriptor.
 */
static int nm_close(struct nm_desc_t *);


/*
 * Try to open, return descriptor if successful, NULL otherwise.
 * An invalid netmap name will return errno = 0;
 */
static struct nm_desc_t *
nm_open(const char *ifname, const char *ring_name, int flags, int ring_flags)
{
        struct nm_desc_t *d;
        u_int n;

        if (strncmp(ifname, "netmap:", 7) && strncmp(ifname, "vale", 4)) {
                errno = 0; /* name not recognised */
                return NULL;
        }
        if (ifname[0] == 'n')
                ifname += 7;
        d = (struct nm_desc_t *)calloc(1, sizeof(*d));
        if (d == NULL) {
                errno = ENOMEM;
                return NULL;
        }
        d->self = d;    /* set this early so nm_close() works */
        d->fd = open("/dev/netmap", O_RDWR);
        if (d->fd < 0)
                goto fail;

        if (flags & NETMAP_SW_RING) {
                d->req.nr_ringid = NETMAP_SW_RING;
        } else {
                u_int r;
                if (flags & NETMAP_HW_RING) /* interpret ring as int */
                        r = (uintptr_t)ring_name;
                else /* interpret ring as numeric string */
                        r = ring_name ? atoi(ring_name) : ~0;
                r = (r < NETMAP_RING_MASK) ? (r | NETMAP_HW_RING) : 0;
                d->req.nr_ringid = r; /* set the ring */
        }
        d->req.nr_ringid |= (flags & ~NETMAP_RING_MASK);
        d->req.nr_version = NETMAP_API;
        strncpy(d->req.nr_name, ifname, sizeof(d->req.nr_name));
        if (ioctl(d->fd, NIOCREGIF, &d->req))
                goto fail;

        d->memsize = d->req.nr_memsize;
        d->mem = mmap(0, d->memsize, PROT_WRITE | PROT_READ, MAP_SHARED,
                        d->fd, 0);
        if (d->mem == NULL)
                goto fail;
        d->nifp = NETMAP_IF(d->mem, d->req.nr_offset);
        if (d->req.nr_ringid & NETMAP_SW_RING) {
                d->first_ring = d->last_ring = d->req.nr_rx_rings;
        } else if (d->req.nr_ringid & NETMAP_HW_RING) {
                d->first_ring = d->last_ring =
                        d->req.nr_ringid & NETMAP_RING_MASK;
        } else {
                d->first_ring = 0;
                d->last_ring = d->req.nr_rx_rings - 1;
        }
        d->cur_ring = d->first_ring;
        for (n = d->first_ring; n <= d->last_ring; n++) {
                struct netmap_ring *ring = NETMAP_RXRING(d->nifp, n);
                ring->flags |= ring_flags;
        }
        return d;

fail:
        nm_close(d);
        errno = EINVAL;
        return NULL;
}


static int
nm_close(struct nm_desc_t *d)
{
        if (d == NULL || d->self != d)
                return EINVAL;
        if (d->mem)
                munmap(d->mem, d->memsize);
        if (d->fd)
                close(d->fd);
        bzero(d, sizeof(*d));
        free(d);
        return 0;
}


/*
 * Same prototype as pcap_dispatch(), only need to cast.
 */
inline /* not really, but disable unused warnings */
static int
nm_dispatch(struct nm_desc_t *d, int cnt, nm_cb_t cb, u_char *arg)
{
        int n = d->last_ring - d->first_ring + 1;
        int c, got = 0, ri = d->cur_ring;

        if (cnt == 0)
                cnt = -1;
        /* cnt == -1 means infinite, but rings have a finite amount
         * of buffers and the int is large enough that we never wrap,
         * so we can omit checking for -1
         */
        for (c=0; c < n && cnt != got; c++) {
                /* compute current ring to use */
                struct netmap_ring *ring;

                ri = d->cur_ring + c;
                if (ri > d->last_ring)
                        ri = d->first_ring;
                ring = NETMAP_RXRING(d->nifp, ri);
                for ( ; ring->avail > 0 && cnt != got; got++) {
                        u_int i = ring->cur;
                        u_int idx = ring->slot[i].buf_idx;
                        u_char *buf = (u_char *)NETMAP_BUF(ring, idx);
                        // XXX should check valid buf
                        // prefetch(buf);
                        d->hdr.len = d->hdr.caplen = ring->slot[i].len;
                        d->hdr.ts = ring->ts;
                        cb(arg, &d->hdr, buf);
                        ring->cur = NETMAP_RING_NEXT(ring, i);
                        ring->avail--;
                }
        }
        d->cur_ring = ri;
        return got;
}

inline /* not really, but disable unused warnings */
static u_char *
nm_next(struct nm_desc_t *d, struct nm_hdr_t *hdr)
{
        int ri = d->cur_ring;

        do {
                /* compute current ring to use */
                struct netmap_ring *ring = NETMAP_RXRING(d->nifp, ri);
                if (ring->avail > 0) {
                        u_int i = ring->cur;
                        u_int idx = ring->slot[i].buf_idx;
                        u_char *buf = (u_char *)NETMAP_BUF(ring, idx);
                        // XXX should check valid buf
                        // prefetch(buf);
                        hdr->ts = ring->ts;
                        hdr->len = hdr->caplen = ring->slot[i].len;
                        ring->cur = NETMAP_RING_NEXT(ring, i);
                        ring->avail--;
                        d->cur_ring = ri;
                        return buf;
                }
                ri++;
                if (ri > d->last_ring)
                        ri = d->first_ring;
        } while (ri != d->cur_ring);
        return NULL; /* nothing found */
}

#endif /* !HAVE_NETMAP_WITH_LIBS */

#endif /* NETMAP_WITH_LIBS */

#endif /* _NET_NETMAP_USER_H_ */