/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2011-2016 Universita` di Pisa
 * 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.
 *
 * 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.
 */

/*
 *
 * Functions and macros 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->cur, ring->head, ring->tail, etc.
 *
 *      ring->slot[i] gives us the i-th slot (we can access
 *              directly len, flags, buf_idx)
 *
 *      char *buf = NETMAP_BUF(ring, x) returns a pointer to
 *              the buffer numbered x
 *
 * All ring indexes (head, cur, tail) should always move forward.
 * To compute the next index in a circular ring you can use
 *      i = nm_ring_next(ring, i);
 *
 * To ease porting apps from pcap to netmap we supply a few functions
 * that can be called to open, close, read and write on netmap in a way
 * similar to libpcap. Note that the read/write function depend on
 * an ioctl()/select()/poll() being issued to refill rings or push
 * packets out.
 *
 * 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_

#define NETMAP_DEVICE_NAME "/dev/netmap"

#ifdef __CYGWIN__
/*
 * we can compile userspace apps with either cygwin or msvc,
 * and we use _WIN32 to identify windows specific code
 */
#ifndef _WIN32
#define _WIN32
#endif  /* _WIN32 */

#endif  /* __CYGWIN__ */

#ifdef _WIN32
#undef NETMAP_DEVICE_NAME
#define NETMAP_DEVICE_NAME "/proc/sys/DosDevices/Global/netmap"
#include <windows.h>
#include <WinDef.h>
#include <sys/cygwin.h>
#endif /* _WIN32 */

#include <stdint.h>
#include <sys/socket.h>         /* apple needs sockaddr */
#include <net/if.h>             /* IFNAMSIZ */
#include <ctype.h>
#include <string.h>     /* memset */
#include <sys/time.h>   /* gettimeofday */

#ifndef likely
#define likely(x)       __builtin_expect(!!(x), 1)
#define unlikely(x)     __builtin_expect(!!(x), 0)
#endif /* likely and unlikely */

#include <net/netmap.h>

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

#define NETMAP_IF(_base, _ofs)  _NETMAP_OFFSET(struct netmap_if *, _base, _ofs)

#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 +            \
                (nifp)->ni_host_tx_rings] )

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

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

/* read the offset field in a ring's slot */
#define NETMAP_ROFFSET(ring, slot)                      \
        ((slot)->ptr & (ring)->offset_mask)

/* update the offset field in a ring's slot */
#define NETMAP_WOFFSET(ring, slot, offset)              \
        do { (slot)->ptr = ((slot)->ptr & ~(ring)->offset_mask) | \
                ((offset) & (ring)->offset_mask); } while (0)

/* obtain the start of the buffer pointed to by  a ring's slot, taking the
 * offset field into account
 */
#define NETMAP_BUF_OFFSET(ring, slot)                   \
        (NETMAP_BUF(ring, (slot)->buf_idx) + NETMAP_ROFFSET(ring, slot))


static inline uint32_t
nm_ring_next(struct netmap_ring *r, uint32_t i)
{
        return ( unlikely(i + 1 == r->num_slots) ? 0 : i + 1);
}


/*
 * Return 1 if we have pending transmissions in the tx ring.
 * When everything is complete ring->head = ring->tail + 1 (modulo ring size)
 */
static inline int
nm_tx_pending(struct netmap_ring *r)
{
        return nm_ring_next(r, r->tail) != r->head;
}

/* Compute the number of slots available in the netmap ring. We use
 * ring->head as explained in the comment above nm_ring_empty(). */
static inline uint32_t
nm_ring_space(struct netmap_ring *ring)
{
        int ret = ring->tail - ring->head;
        if (ret < 0)
                ret += ring->num_slots;
        return ret;
}

#ifndef ND /* debug macros */
/* debug support */
#define ND(_fmt, ...) do {} while(0)
#define D(_fmt, ...)                                            \
        do {                                                    \
                struct timeval _t0;                             \
                gettimeofday(&_t0, NULL);                       \
                fprintf(stderr, "%03d.%06d %s [%d] " _fmt "\n", \
                    (int)(_t0.tv_sec % 1000), (int)_t0.tv_usec, \
                    __FUNCTION__, __LINE__, ##__VA_ARGS__);     \
        } while (0)

/* Rate limited version of "D", lps indicates how many per second */
#define RD(lps, format, ...)                                    \
    do {                                                        \
        static int __t0, __cnt;                                 \
        struct timeval __xxts;                                  \
        gettimeofday(&__xxts, NULL);                            \
        if (__t0 != __xxts.tv_sec) {                            \
            __t0 = __xxts.tv_sec;                               \
            __cnt = 0;                                          \
        }                                                       \
        if (__cnt++ < lps) {                                    \
            D(format, ##__VA_ARGS__);                           \
        }                                                       \
    } while (0)
#endif

/*
 * this is a slightly optimized copy routine which rounds
 * to multiple of 64 bytes and is often faster than dealing
 * with other odd sizes. We assume there is enough room
 * in the source and destination buffers.
 */
static inline void
nm_pkt_copy(const void *_src, void *_dst, int l)
{
        const uint64_t *src = (const uint64_t *)_src;
        uint64_t *dst = (uint64_t *)_dst;

        if (unlikely(l >= 1024 || l % 64)) {
                memcpy(dst, src, l);
                return;
        }
        for (; likely(l > 0); l-=64) {
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
                *dst++ = *src++;
        }
}

#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 <stdio.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/errno.h>  /* EINVAL */
#include <fcntl.h>      /* O_RDWR */
#include <unistd.h>     /* close() */
#include <signal.h>
#include <stdlib.h>

struct nm_pkthdr {      /* first part is the same as pcap_pkthdr */
        struct timeval  ts;
        uint32_t        caplen;
        uint32_t        len;

        uint64_t flags; /* NM_MORE_PKTS etc */
#define NM_MORE_PKTS    1
        struct nm_desc *d;
        struct netmap_slot *slot;
        uint8_t *buf;
};

struct nm_stat {        /* same as pcap_stat    */
        u_int   ps_recv;
        u_int   ps_drop;
        u_int   ps_ifdrop;
#ifdef WIN32 /* XXX or _WIN32 ? */
        u_int   bs_capt;
#endif /* WIN32 */
};

#define NM_ERRBUF_SIZE  512

struct nm_desc {
        struct nm_desc *self; /* point to self if netmap. */
        int fd;
        void *mem;
        size_t memsize;
        int done_mmap;  /* set if mem is the result of mmap */
        struct netmap_if * const nifp;
        uint16_t first_tx_ring, last_tx_ring, cur_tx_ring;
        uint16_t first_rx_ring, last_rx_ring, cur_rx_ring;
        struct nmreq req;       /* also contains the nr_name = ifname */
        struct nm_pkthdr hdr;

        /*
         * The memory contains netmap_if, rings and then buffers.
         * Given a pointer (e.g. to nm_inject) we can compare with
         * mem/buf_start/buf_end to tell if it is a buffer or
         * some other descriptor in our region.
         * We also store a pointer to some ring as it helps in the
         * translation from buffer indexes to addresses.
         */
        struct netmap_ring * const some_ring;
        void * const buf_start;
        void * const buf_end;
        /* parameters from pcap_open_live */
        int snaplen;
        int promisc;
        int to_ms;
        char *errbuf;

        /* save flags so we can restore them on close */
        uint32_t if_flags;
        uint32_t if_reqcap;
        uint32_t if_curcap;

        struct nm_stat st;
        char msg[NM_ERRBUF_SIZE];
};

/*
 * when the descriptor is open correctly, d->self == d
 * Eventually we should also use some magic number.
 */
#define P2NMD(p)                ((const struct nm_desc *)(p))
#define IS_NETMAP_DESC(d)       ((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_pkthdr *, const u_char *d);

/*
 *--- the pcap-like API ---
 *
 * nm_open() opens a file descriptor, binds to a port and maps memory.
 *
 * ifname       (netmap:foo or vale:foo) is the port name
 *              a suffix can indicate the following:
 *              ^               bind the host (sw) ring pair
 *              *               bind host and NIC ring pairs
 *              -NN             bind individual NIC ring pair
 *              {NN             bind master side of pipe NN
 *              }NN             bind slave side of pipe NN
 *              a suffix starting with / and the following flags,
 *              in any order:
 *              x               exclusive access
 *              z               zero copy monitor (both tx and rx)
 *              t               monitor tx side (copy monitor)
 *              r               monitor rx side (copy monitor)
 *              R               bind only RX ring(s)
 *              T               bind only TX ring(s)
 *
 * req          provides the initial values of nmreq before parsing ifname.
 *              Remember that the ifname parsing will override the ring
 *              number in nm_ringid, and part of nm_flags;
 * flags        special functions, normally 0
 *              indicates which fields of *arg are significant
 * arg          special functions, normally NULL
 *              if passed a netmap_desc with mem != NULL,
 *              use that memory instead of mmap.
 */

static struct nm_desc *nm_open(const char *ifname, const struct nmreq *req,
        uint64_t flags, const struct nm_desc *arg);

/*
 * nm_open can import some fields from the parent descriptor.
 * These flags control which ones.
 * Also in flags you can specify NETMAP_NO_TX_POLL and NETMAP_DO_RX_POLL,
 * which set the initial value for these flags.
 * Note that the 16 low bits of the flags are reserved for data
 * that may go into the nmreq.
 */
enum {
        NM_OPEN_NO_MMAP =       0x040000, /* reuse mmap from parent */
        NM_OPEN_IFNAME =        0x080000, /* nr_name, nr_ringid, nr_flags */
        NM_OPEN_ARG1 =          0x100000,
        NM_OPEN_ARG2 =          0x200000,
        NM_OPEN_ARG3 =          0x400000,
        NM_OPEN_RING_CFG =      0x800000, /* tx|rx rings|slots */
};


/*
 * nm_close()   closes and restores the port to its previous state
 */

static int nm_close(struct nm_desc *);

/*
 * nm_mmap()    do mmap or inherit from parent if the nr_arg2
 *              (memory block) matches.
 */

static int nm_mmap(struct nm_desc *, const struct nm_desc *);

/*
 * nm_inject() is the same as pcap_inject()
 * nm_dispatch() is the same as pcap_dispatch()
 * nm_nextpkt() is the same as pcap_next()
 */

static int nm_inject(struct nm_desc *, const void *, size_t);
static int nm_dispatch(struct nm_desc *, int, nm_cb_t, u_char *);
static u_char *nm_nextpkt(struct nm_desc *, struct nm_pkthdr *);

#ifdef _WIN32

intptr_t _get_osfhandle(int); /* defined in io.h in windows */

/*
 * In windows we do not have yet native poll support, so we keep track
 * of file descriptors associated to netmap ports to emulate poll on
 * them and fall back on regular poll on other file descriptors.
 */
struct win_netmap_fd_list {
        struct win_netmap_fd_list *next;
        int win_netmap_fd;
        HANDLE win_netmap_handle;
};

/*
 * list head containing all the netmap opened fd and their
 * windows HANDLE counterparts
 */
static struct win_netmap_fd_list *win_netmap_fd_list_head;

static void
win_insert_fd_record(int fd)
{
        struct win_netmap_fd_list *curr;

        for (curr = win_netmap_fd_list_head; curr; curr = curr->next) {
                if (fd == curr->win_netmap_fd) {
                        return;
                }
        }
        curr = calloc(1, sizeof(*curr));
        curr->next = win_netmap_fd_list_head;
        curr->win_netmap_fd = fd;
        curr->win_netmap_handle = IntToPtr(_get_osfhandle(fd));
        win_netmap_fd_list_head = curr;
}

void
win_remove_fd_record(int fd)
{
        struct win_netmap_fd_list *curr = win_netmap_fd_list_head;
        struct win_netmap_fd_list *prev = NULL;
        for (; curr ; prev = curr, curr = curr->next) {
                if (fd != curr->win_netmap_fd)
                        continue;
                /* found the entry */
                if (prev == NULL) { /* we are freeing the first entry */
                        win_netmap_fd_list_head = curr->next;
                } else {
                        prev->next = curr->next;
                }
                free(curr);
                break;
        }
}


HANDLE
win_get_netmap_handle(int fd)
{
        struct win_netmap_fd_list *curr;

        for (curr = win_netmap_fd_list_head; curr; curr = curr->next) {
                if (fd == curr->win_netmap_fd) {
                        return curr->win_netmap_handle;
                }
        }
        return NULL;
}

/*
 * we need to wrap ioctl and mmap, at least for the netmap file descriptors
 */

/*
 * use this function only from netmap_user.h internal functions
 * same as ioctl, returns 0 on success and -1 on error
 */
static int
win_nm_ioctl_internal(HANDLE h, int32_t ctlCode, void *arg)
{
        DWORD bReturn = 0, szIn, szOut;
        BOOL ioctlReturnStatus;
        void *inParam = arg, *outParam = arg;

        switch (ctlCode) {
        case NETMAP_POLL:
                szIn = sizeof(POLL_REQUEST_DATA);
                szOut = sizeof(POLL_REQUEST_DATA);
                break;
        case NETMAP_MMAP:
                szIn = 0;
                szOut = sizeof(void*);
                inParam = NULL; /* nothing on input */
                break;
        case NIOCTXSYNC:
        case NIOCRXSYNC:
                szIn = 0;
                szOut = 0;
                break;
        case NIOCREGIF:
                szIn = sizeof(struct nmreq);
                szOut = sizeof(struct nmreq);
                break;
        case NIOCCONFIG:
                D("unsupported NIOCCONFIG!");
                return -1;

        default: /* a regular ioctl */
                D("invalid ioctl %x on netmap fd", ctlCode);
                return -1;
        }

        ioctlReturnStatus = DeviceIoControl(h,
                                ctlCode, inParam, szIn,
                                outParam, szOut,
                                &bReturn, NULL);
        // XXX note windows returns 0 on error or async call, 1 on success
        // we could call GetLastError() to figure out what happened
        return ioctlReturnStatus ? 0 : -1;
}

/*
 * this function is what must be called from user-space programs
 * same as ioctl, returns 0 on success and -1 on error
 */
static int
win_nm_ioctl(int fd, int32_t ctlCode, void *arg)
{
        HANDLE h = win_get_netmap_handle(fd);

        if (h == NULL) {
                return ioctl(fd, ctlCode, arg);
        } else {
                return win_nm_ioctl_internal(h, ctlCode, arg);
        }
}

#define ioctl win_nm_ioctl /* from now on, within this file ... */

/*
 * We cannot use the native mmap on windows
 * The only parameter used is "fd", the other ones are just declared to
 * make this signature comparable to the FreeBSD/Linux one
 */
static void *
win32_mmap_emulated(void *addr, size_t length, int prot, int flags, int fd, int32_t offset)
{
        HANDLE h = win_get_netmap_handle(fd);

        if (h == NULL) {
                return mmap(addr, length, prot, flags, fd, offset);
        } else {
                MEMORY_ENTRY ret;

                return win_nm_ioctl_internal(h, NETMAP_MMAP, &ret) ?
                        NULL : ret.pUsermodeVirtualAddress;
        }
}

#define mmap win32_mmap_emulated

#include <sys/poll.h> /* XXX needed to use the structure pollfd */

static int
win_nm_poll(struct pollfd *fds, int nfds, int timeout)
{
        HANDLE h;

        if (nfds != 1 || fds == NULL || (h = win_get_netmap_handle(fds->fd)) == NULL) {;
                return poll(fds, nfds, timeout);
        } else {
                POLL_REQUEST_DATA prd;

                prd.timeout = timeout;
                prd.events = fds->events;

                win_nm_ioctl_internal(h, NETMAP_POLL, &prd);
                if ((prd.revents == POLLERR) || (prd.revents == STATUS_TIMEOUT)) {
                        return -1;
                }
                return 1;
        }
}

#define poll win_nm_poll

static int
win_nm_open(char* pathname, int flags)
{

        if (strcmp(pathname, NETMAP_DEVICE_NAME) == 0) {
                int fd = open(NETMAP_DEVICE_NAME, O_RDWR);
                if (fd < 0) {
                        return -1;
                }

                win_insert_fd_record(fd);
                return fd;
        } else {
                return open(pathname, flags);
        }
}

#define open win_nm_open

static int
win_nm_close(int fd)
{
        if (fd != -1) {
                close(fd);
                if (win_get_netmap_handle(fd) != NULL) {
                        win_remove_fd_record(fd);
                }
        }
        return 0;
}

#define close win_nm_close

#endif /* _WIN32 */

static int
nm_is_identifier(const char *s, const char *e)
{
        for (; s != e; s++) {
                if (!isalnum(*s) && *s != '_') {
                        return 0;
                }
        }

        return 1;
}

#define MAXERRMSG 80
static int
nm_parse(const char *ifname, struct nm_desc *d, char *err)
{
        int is_vale;
        const char *port = NULL;
        const char *vpname = NULL;
        u_int namelen;
        uint32_t nr_ringid = 0, nr_flags;
        char errmsg[MAXERRMSG] = "", *tmp;
        long num;
        uint16_t nr_arg2 = 0;
        enum { P_START, P_RNGSFXOK, P_GETNUM, P_FLAGS, P_FLAGSOK, P_MEMID } p_state;

        errno = 0;

        is_vale = (ifname[0] == 'v');
        if (is_vale) {
                port = index(ifname, ':');
                if (port == NULL) {
                        snprintf(errmsg, MAXERRMSG,
                                 "missing ':' in vale name");
                        goto fail;
                }

                if (!nm_is_identifier(ifname + 4, port)) {
                        snprintf(errmsg, MAXERRMSG, "invalid bridge name");
                        goto fail;
                }

                vpname = ++port;
        } else {
                ifname += 7;
                port = ifname;
        }

        /* scan for a separator */
        for (; *port && !index("-*^{}/@", *port); port++)
                ;

        if (is_vale && !nm_is_identifier(vpname, port)) {
                snprintf(errmsg, MAXERRMSG, "invalid bridge port name");
                goto fail;
        }

        namelen = port - ifname;
        if (namelen >= sizeof(d->req.nr_name)) {
                snprintf(errmsg, MAXERRMSG, "name too long");
                goto fail;
        }
        memcpy(d->req.nr_name, ifname, namelen);
        d->req.nr_name[namelen] = '\0';

        p_state = P_START;
        nr_flags = NR_REG_ALL_NIC; /* default for no suffix */
        while (*port) {
                switch (p_state) {
                case P_START:
                        switch (*port) {
                        case '^': /* only SW ring */
                                nr_flags = NR_REG_SW;
                                p_state = P_RNGSFXOK;
                                break;
                        case '*': /* NIC and SW */
                                nr_flags = NR_REG_NIC_SW;
                                p_state = P_RNGSFXOK;
                                break;
                        case '-': /* one NIC ring pair */
                                nr_flags = NR_REG_ONE_NIC;
                                p_state = P_GETNUM;
                                break;
                        case '{': /* pipe (master endpoint) */
                                nr_flags = NR_REG_PIPE_MASTER;
                                p_state = P_GETNUM;
                                break;
                        case '}': /* pipe (slave endpoint) */
                                nr_flags = NR_REG_PIPE_SLAVE;
                                p_state = P_GETNUM;
                                break;
                        case '/': /* start of flags */
                                p_state = P_FLAGS;
                                break;
                        case '@': /* start of memid */
                                p_state = P_MEMID;
                                break;
                        default:
                                snprintf(errmsg, MAXERRMSG, "unknown modifier: '%c'", *port);
                                goto fail;
                        }
                        port++;
                        break;
                case P_RNGSFXOK:
                        switch (*port) {
                        case '/':
                                p_state = P_FLAGS;
                                break;
                        case '@':
                                p_state = P_MEMID;
                                break;
                        default:
                                snprintf(errmsg, MAXERRMSG, "unexpected character: '%c'", *port);
                                goto fail;
                        }
                        port++;
                        break;
                case P_GETNUM:
                        num = strtol(port, &tmp, 10);
                        if (num < 0 || num >= NETMAP_RING_MASK) {
                                snprintf(errmsg, MAXERRMSG, "'%ld' out of range [0, %d)",
                                                num, NETMAP_RING_MASK);
                                goto fail;
                        }
                        port = tmp;
                        nr_ringid = num & NETMAP_RING_MASK;
                        p_state = P_RNGSFXOK;
                        break;
                case P_FLAGS:
                case P_FLAGSOK:
                        if (*port == '@') {
                                port++;
                                p_state = P_MEMID;
                                break;
                        }
                        switch (*port) {
                        case 'x':
                                nr_flags |= NR_EXCLUSIVE;
                                break;
                        case 'z':
                                nr_flags |= NR_ZCOPY_MON;
                                break;
                        case 't':
                                nr_flags |= NR_MONITOR_TX;
                                break;
                        case 'r':
                                nr_flags |= NR_MONITOR_RX;
                                break;
                        case 'R':
                                nr_flags |= NR_RX_RINGS_ONLY;
                                break;
                        case 'T':
                                nr_flags |= NR_TX_RINGS_ONLY;
                                break;
                        default:
                                snprintf(errmsg, MAXERRMSG, "unrecognized flag: '%c'", *port);
                                goto fail;
                        }
                        port++;
                        p_state = P_FLAGSOK;
                        break;
                case P_MEMID:
                        if (nr_arg2 != 0) {
                                snprintf(errmsg, MAXERRMSG, "double setting of memid");
                                goto fail;
                        }
                        num = strtol(port, &tmp, 10);
                        if (num <= 0) {
                                snprintf(errmsg, MAXERRMSG, "invalid memid %ld, must be >0", num);
                                goto fail;
                        }
                        port = tmp;
                        nr_arg2 = num;
                        p_state = P_RNGSFXOK;
                        break;
                }
        }
        if (p_state != P_START && p_state != P_RNGSFXOK && p_state != P_FLAGSOK) {
                snprintf(errmsg, MAXERRMSG, "unexpected end of port name");
                goto fail;
        }
        ND("flags: %s %s %s %s",
                        (nr_flags & NR_EXCLUSIVE) ? "EXCLUSIVE" : "",
                        (nr_flags & NR_ZCOPY_MON) ? "ZCOPY_MON" : "",
                        (nr_flags & NR_MONITOR_TX) ? "MONITOR_TX" : "",
                        (nr_flags & NR_MONITOR_RX) ? "MONITOR_RX" : "");

        d->req.nr_flags |= nr_flags;
        d->req.nr_ringid |= nr_ringid;
        d->req.nr_arg2 = nr_arg2;

        d->self = d;

        return 0;
fail:
        if (!errno)
                errno = EINVAL;
        if (err)
                strncpy(err, errmsg, MAXERRMSG);
        return -1;
}

/*
 * Try to open, return descriptor if successful, NULL otherwise.
 * An invalid netmap name will return errno = 0;
 * You can pass a pointer to a pre-filled nm_desc to add special
 * parameters. Flags is used as follows
 * NM_OPEN_NO_MMAP      use the memory from arg, only XXX avoid mmap
 *                      if the nr_arg2 (memory block) matches.
 * NM_OPEN_ARG1         use req.nr_arg1 from arg
 * NM_OPEN_ARG2         use req.nr_arg2 from arg
 * NM_OPEN_RING_CFG     user ring config from arg
 */
static struct nm_desc *
nm_open(const char *ifname, const struct nmreq *req,
        uint64_t new_flags, const struct nm_desc *arg)
{
        struct nm_desc *d = NULL;
        const struct nm_desc *parent = arg;
        char errmsg[MAXERRMSG] = "";
        uint32_t nr_reg;

        if (strncmp(ifname, "netmap:", 7) &&
                        strncmp(ifname, NM_BDG_NAME, strlen(NM_BDG_NAME))) {
                errno = 0; /* name not recognised, not an error */
                return NULL;
        }

        d = (struct nm_desc *)calloc(1, sizeof(*d));
        if (d == NULL) {
                snprintf(errmsg, MAXERRMSG, "nm_desc alloc failure");
                errno = ENOMEM;
                return NULL;
        }
        d->self = d;    /* set this early so nm_close() works */
        d->fd = open(NETMAP_DEVICE_NAME, O_RDWR);
        if (d->fd < 0) {
                snprintf(errmsg, MAXERRMSG, "cannot open /dev/netmap: %s", strerror(errno));
                goto fail;
        }

        if (req)
                d->req = *req;

        if (!(new_flags & NM_OPEN_IFNAME)) {
                if (nm_parse(ifname, d, errmsg) < 0)
                        goto fail;
        }

        d->req.nr_version = NETMAP_API;
        d->req.nr_ringid &= NETMAP_RING_MASK;

        /* optionally import info from parent */
        if (IS_NETMAP_DESC(parent) && new_flags) {
                if (new_flags & NM_OPEN_ARG1)
                        D("overriding ARG1 %d", parent->req.nr_arg1);
                d->req.nr_arg1 = new_flags & NM_OPEN_ARG1 ?
                        parent->req.nr_arg1 : 4;
                if (new_flags & NM_OPEN_ARG2) {
                        D("overriding ARG2 %d", parent->req.nr_arg2);
                        d->req.nr_arg2 =  parent->req.nr_arg2;
                }
                if (new_flags & NM_OPEN_ARG3)
                        D("overriding ARG3 %d", parent->req.nr_arg3);
                d->req.nr_arg3 = new_flags & NM_OPEN_ARG3 ?
                        parent->req.nr_arg3 : 0;
                if (new_flags & NM_OPEN_RING_CFG) {
                        D("overriding RING_CFG");
                        d->req.nr_tx_slots = parent->req.nr_tx_slots;
                        d->req.nr_rx_slots = parent->req.nr_rx_slots;
                        d->req.nr_tx_rings = parent->req.nr_tx_rings;
                        d->req.nr_rx_rings = parent->req.nr_rx_rings;
                }
                if (new_flags & NM_OPEN_IFNAME) {
                        D("overriding ifname %s ringid 0x%x flags 0x%x",
                                parent->req.nr_name, parent->req.nr_ringid,
                                parent->req.nr_flags);
                        memcpy(d->req.nr_name, parent->req.nr_name,
                                sizeof(d->req.nr_name));
                        d->req.nr_ringid = parent->req.nr_ringid;
                        d->req.nr_flags = parent->req.nr_flags;
                }
        }
        /* add the *XPOLL flags */
        d->req.nr_ringid |= new_flags & (NETMAP_NO_TX_POLL | NETMAP_DO_RX_POLL);

        if (ioctl(d->fd, NIOCREGIF, &d->req)) {
                snprintf(errmsg, MAXERRMSG, "NIOCREGIF failed: %s", strerror(errno));
                goto fail;
        }

        nr_reg = d->req.nr_flags & NR_REG_MASK;

        if (nr_reg == NR_REG_SW) { /* host stack */
                d->first_tx_ring = d->last_tx_ring = d->req.nr_tx_rings;
                d->first_rx_ring = d->last_rx_ring = d->req.nr_rx_rings;
        } else if (nr_reg ==  NR_REG_ALL_NIC) { /* only nic */
                d->first_tx_ring = 0;
                d->first_rx_ring = 0;
                d->last_tx_ring = d->req.nr_tx_rings - 1;
                d->last_rx_ring = d->req.nr_rx_rings - 1;
        } else if (nr_reg ==  NR_REG_NIC_SW) {
                d->first_tx_ring = 0;
                d->first_rx_ring = 0;
                d->last_tx_ring = d->req.nr_tx_rings;
                d->last_rx_ring = d->req.nr_rx_rings;
        } else if (nr_reg == NR_REG_ONE_NIC) {
                /* XXX check validity */
                d->first_tx_ring = d->last_tx_ring =
                d->first_rx_ring = d->last_rx_ring = d->req.nr_ringid & NETMAP_RING_MASK;
        } else { /* pipes */
                d->first_tx_ring = d->last_tx_ring = 0;
                d->first_rx_ring = d->last_rx_ring = 0;
        }

        /* if parent is defined, do nm_mmap() even if NM_OPEN_NO_MMAP is set */
        if ((!(new_flags & NM_OPEN_NO_MMAP) || parent) && nm_mmap(d, parent)) {
                snprintf(errmsg, MAXERRMSG, "mmap failed: %s", strerror(errno));
                goto fail;
        }


#ifdef DEBUG_NETMAP_USER
    { /* debugging code */
        int i;

        D("%s tx %d .. %d %d rx %d .. %d %d", ifname,
                d->first_tx_ring, d->last_tx_ring, d->req.nr_tx_rings,
                d->first_rx_ring, d->last_rx_ring, d->req.nr_rx_rings);
        for (i = 0; i <= d->req.nr_tx_rings; i++) {
                struct netmap_ring *r = NETMAP_TXRING(d->nifp, i);
                D("TX%d %p h %d c %d t %d", i, r, r->head, r->cur, r->tail);
        }
        for (i = 0; i <= d->req.nr_rx_rings; i++) {
                struct netmap_ring *r = NETMAP_RXRING(d->nifp, i);
                D("RX%d %p h %d c %d t %d", i, r, r->head, r->cur, r->tail);
        }
    }
#endif /* debugging */

        d->cur_tx_ring = d->first_tx_ring;
        d->cur_rx_ring = d->first_rx_ring;
        return d;

fail:
        nm_close(d);
        if (errmsg[0])
                D("%s %s", errmsg, ifname);
        if (errno == 0)
                errno = EINVAL;
        return NULL;
}


static int
nm_close(struct nm_desc *d)
{
        /*
         * ugly trick to avoid unused warnings
         */
        static void *__xxzt[] __attribute__ ((unused))  =
                { (void *)nm_open, (void *)nm_inject,
                  (void *)nm_dispatch, (void *)nm_nextpkt } ;

        if (d == NULL || d->self != d)
                return EINVAL;
        if (d->done_mmap && d->mem)
                munmap(d->mem, d->memsize);
        if (d->fd != -1) {
                close(d->fd);
        }

        bzero((char *)d, sizeof(*d));
        free(d);
        return 0;
}


static int
nm_mmap(struct nm_desc *d, const struct nm_desc *parent)
{
        if (d->done_mmap)
                return 0;

        if (IS_NETMAP_DESC(parent) && parent->mem &&
            parent->req.nr_arg2 == d->req.nr_arg2) {
                /* do not mmap, inherit from parent */
                D("do not mmap, inherit from parent");
                d->memsize = parent->memsize;
                d->mem = parent->mem;
        } else {
                /* XXX TODO: check if memsize is too large (or there is overflow) */
                d->memsize = d->req.nr_memsize;
                d->mem = mmap(0, d->memsize, PROT_WRITE | PROT_READ, MAP_SHARED,
                                d->fd, 0);
                if (d->mem == MAP_FAILED) {
                        goto fail;
                }
                d->done_mmap = 1;
        }
        {
                struct netmap_if *nifp = NETMAP_IF(d->mem, d->req.nr_offset);
                struct netmap_ring *r = NETMAP_RXRING(nifp, d->first_rx_ring);
                if ((void *)r == (void *)nifp) {
                        /* the descriptor is open for TX only */
                        r = NETMAP_TXRING(nifp, d->first_tx_ring);
                }

                *(struct netmap_if **)(uintptr_t)&(d->nifp) = nifp;
                *(struct netmap_ring **)(uintptr_t)&d->some_ring = r;
                *(void **)(uintptr_t)&d->buf_start = NETMAP_BUF(r, 0);
                *(void **)(uintptr_t)&d->buf_end =
                        (char *)d->mem + d->memsize;
        }

        return 0;

fail:
        return EINVAL;
}

/*
 * Same prototype as pcap_inject(), only need to cast.
 */
static int
nm_inject(struct nm_desc *d, const void *buf, size_t size)
{
        u_int c, n = d->last_tx_ring - d->first_tx_ring + 1,
                ri = d->cur_tx_ring;

        for (c = 0; c < n ; c++, ri++) {
                /* compute current ring to use */
                struct netmap_ring *ring;
                uint32_t i, j, idx;
                size_t rem;

                if (ri > d->last_tx_ring)
                        ri = d->first_tx_ring;
                ring = NETMAP_TXRING(d->nifp, ri);
                rem = size;
                j = ring->cur;
                while (rem > ring->nr_buf_size && j != ring->tail) {
                        rem -= ring->nr_buf_size;
                        j = nm_ring_next(ring, j);
                }
                if (j == ring->tail && rem > 0)
                        continue;
                i = ring->cur;
                while (i != j) {
                        idx = ring->slot[i].buf_idx;
                        ring->slot[i].len = ring->nr_buf_size;
                        ring->slot[i].flags = NS_MOREFRAG;
                        nm_pkt_copy(buf, NETMAP_BUF(ring, idx), ring->nr_buf_size);
                        i = nm_ring_next(ring, i);
                        buf = (const char *)buf + ring->nr_buf_size;
                }
                idx = ring->slot[i].buf_idx;
                ring->slot[i].len = rem;
                ring->slot[i].flags = 0;
                nm_pkt_copy(buf, NETMAP_BUF(ring, idx), rem);
                ring->head = ring->cur = nm_ring_next(ring, i);
                d->cur_tx_ring = ri;
                return size;
        }
        return 0; /* fail */
}


/*
 * Same prototype as pcap_dispatch(), only need to cast.
 */
static int
nm_dispatch(struct nm_desc *d, int cnt, nm_cb_t cb, u_char *arg)
{
        int n = d->last_rx_ring - d->first_rx_ring + 1;
        int c, got = 0, ri = d->cur_rx_ring;
        d->hdr.buf = NULL;
        d->hdr.flags = NM_MORE_PKTS;
        d->hdr.d = d;

        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++, ri++) {
                /* compute current ring to use */
                struct netmap_ring *ring;

                if (ri > d->last_rx_ring)
                        ri = d->first_rx_ring;
                ring = NETMAP_RXRING(d->nifp, ri);
                for ( ; !nm_ring_empty(ring) && cnt != got; got++) {
                        u_int idx, i;
                        u_char *oldbuf;
                        struct netmap_slot *slot;
                        if (d->hdr.buf) { /* from previous round */
                                cb(arg, &d->hdr, d->hdr.buf);
                        }
                        i = ring->cur;
                        slot = &ring->slot[i];
                        idx = slot->buf_idx;
                        /* d->cur_rx_ring doesn't change inside this loop, but
                         * set it here, so it reflects d->hdr.buf's ring */
                        d->cur_rx_ring = ri;
                        d->hdr.slot = slot;
                        oldbuf = d->hdr.buf = (u_char *)NETMAP_BUF(ring, idx);
                        // __builtin_prefetch(buf);
                        d->hdr.len = d->hdr.caplen = slot->len;
                        while (slot->flags & NS_MOREFRAG) {
                                u_char *nbuf;
                                u_int oldlen = slot->len;
                                i = nm_ring_next(ring, i);
                                slot = &ring->slot[i];
                                d->hdr.len += slot->len;
                                nbuf = (u_char *)NETMAP_BUF(ring, slot->buf_idx);
                                if (oldbuf != NULL && (uint32_t)(nbuf - oldbuf) == ring->nr_buf_size &&
                                                oldlen == ring->nr_buf_size) {
                                        d->hdr.caplen += slot->len;
                                        oldbuf = nbuf;
                                } else {
                                        oldbuf = NULL;
                                }
                        }
                        d->hdr.ts = ring->ts;
                        ring->head = ring->cur = nm_ring_next(ring, i);
                }
        }
        if (d->hdr.buf) { /* from previous round */
                d->hdr.flags = 0;
                cb(arg, &d->hdr, d->hdr.buf);
        }
        return got;
}

static u_char *
nm_nextpkt(struct nm_desc *d, struct nm_pkthdr *hdr)
{
        int ri = d->cur_rx_ring;

        do {
                /* compute current ring to use */
                struct netmap_ring *ring = NETMAP_RXRING(d->nifp, ri);
                if (!nm_ring_empty(ring)) {
                        u_int i = ring->cur;
                        u_int idx = ring->slot[i].buf_idx;
                        u_char *buf = (u_char *)NETMAP_BUF(ring, idx);

                        // __builtin_prefetch(buf);
                        hdr->ts = ring->ts;
                        hdr->len = hdr->caplen = ring->slot[i].len;
                        ring->cur = nm_ring_next(ring, i);
                        /* we could postpone advancing head if we want
                         * to hold the buffer. This can be supported in
                         * the future.
                         */
                        ring->head = ring->cur;
                        d->cur_rx_ring = ri;
                        return buf;
                }
                ri++;
                if (ri > d->last_rx_ring)
                        ri = d->first_rx_ring;
        } while (ri != d->cur_rx_ring);
        return NULL; /* nothing found */
}

#endif /* !HAVE_NETMAP_WITH_LIBS */

#endif /* NETMAP_WITH_LIBS */

#endif /* _NET_NETMAP_USER_H_ */