MFH: sync the netmap code with the one in HEAD

(enhanced VALE switch, netmap pipes, emulated netmap mode).
See details in the log for svn 261909.

1 files changed, 620 insertions, 38 deletions

diff --git a/sys/net/netmap_user.h b/sys/net/netmap_user.h
index fcb5cb3..9c3a4c1 100644
--- a/sys/net/netmap_user.h
+++ b/sys/net/netmap_user.h
@@ -1,40 +1,34 @@
 /*
- * Copyright (C) 2011 Matteo Landi, Luigi Rizzo. All rights reserved.
- * 
+ * Copyright (C) 2011-2014 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:
- * 
+ * 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 authors nor the names of their contributors
- *      may be used to endorse or promote products derived from this
- *      software without specific prior written permission.
- * 
- * THIS SOFTWARE IS PROVIDED BY MATTEO LANDI AND CONTRIBUTORS "AS IS" AND
+ *      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 MATTEO LANDI 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.
+ * 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.
+ * 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:
@@ -49,22 +43,44 @@
  *		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)
+ *		directly len, flags, buf_idx)
  *
  *	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);
+ * 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 fuctions
+ * 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_
 
+#include <stdint.h>
+#include <sys/socket.h>		/* apple needs sockaddr */
+#include <net/if.h>		/* IFNAMSIZ */
+
+#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(b, o)	_NETMAP_OFFSET(struct netmap_if *, b, o)
+#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] )
@@ -77,19 +93,585 @@
 
 #define NETMAP_BUF_IDX(ring, buf)			\
 	( ((char *)(buf) - ((char *)(ring) + (ring)->buf_ofs) ) / \
-		(ring)->nr_buf_size ) 
+		(ring)->nr_buf_size )
+
+
+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;
+}
+
 
-#define	NETMAP_RING_NEXT(r, i)				\
-	((i)+1 == (r)->num_slots ? 0 : (i) + 1 )
+static inline uint32_t
+nm_ring_space(struct netmap_ring *ring)
+{
+        int ret = ring->tail - ring->cur;
+        if (ret < 0)
+                ret += ring->num_slots;
+        return ret;
+}
 
-#define	NETMAP_RING_FIRST_RESERVED(r)			\
-	( (r)->cur < (r)->reserved ?			\
-	  (r)->cur + (r)->num_slots - (r)->reserved :	\
-	  (r)->cur - (r)->reserved )
 
+#ifdef NETMAP_WITH_LIBS
 /*
- * Return 1 if the given tx ring is empty.
+ * Support for simple I/O libraries.
+ * Include other system headers required for compiling this.
  */
-#define NETMAP_TX_RING_EMPTY(r)	((r)->avail >= (r)->num_slots - 1)
+
+#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 <unistd.h>	/* close() */
+#include <signal.h>
+#include <stdlib.h>
+
+#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
+
+struct nm_pkthdr {	/* same as pcap_pkthdr */
+	struct timeval	ts;
+	uint32_t	caplen;
+	uint32_t	len;
+};
+
+struct nm_stat {	/* same as pcap_stat	*/
+	u_int	ps_recv;
+	u_int	ps_drop;
+	u_int	ps_ifdrop;
+#ifdef 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;
+	int 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)		((struct nm_desc *)(p))
+#define IS_NETMAP_DESC(d)	((d) && P2NMD(d)->self == P2NMD(d))
+#define NETMAP_FD(d)		(P2NMD(d)->fd)
+
+
+/*
+ * 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.
+ *
+ * XXX only for multiples of 64 bytes, non overlapped.
+ */
+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)) {
+		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++;
+	}
+}
+
+
+/*
+ * 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 follwing:
+ *		^		bind the host (sw) ring pair
+ *		*		bind host and NIC ring pairs (transparent)
+ *		-NN		bind individual NIC ring pair
+ *		{NN		bind master side of pipe NN
+ *		}NN		bind slave side of pipe NN
+ *
+ * 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_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 *);
+
+
+/*
+ * 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
+ *			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;
+	u_int namelen;
+	uint32_t nr_ringid = 0, nr_flags;
+	const char *port = NULL;
+	const char *errmsg = NULL;
+
+	if (strncmp(ifname, "netmap:", 7) && strncmp(ifname, "vale", 4)) {
+		errno = 0; /* name not recognised, not an error */
+		return NULL;
+	}
+	if (ifname[0] == 'n')
+		ifname += 7;
+	/* scan for a separator */
+	for (port = ifname; *port && !index("-*^{}", *port); port++)
+		;
+	namelen = port - ifname;
+	if (namelen >= sizeof(d->req.nr_name)) {
+		errmsg = "name too long";
+		goto fail;
+	}
+	switch (*port) {
+	default:  /* '\0', no suffix */
+		nr_flags = NR_REG_ALL_NIC;
+		break;
+	case '-': /* one NIC */
+		nr_flags = NR_REG_ONE_NIC;
+		nr_ringid = atoi(port + 1);
+		break;
+	case '*': /* NIC and SW, ignore port */
+		nr_flags = NR_REG_NIC_SW;
+		if (port[1]) {
+			errmsg = "invalid port for nic+sw";
+			goto fail;
+		}
+		break;
+	case '^': /* only sw ring */
+		nr_flags = NR_REG_SW;
+		if (port[1]) {
+			errmsg = "invalid port for sw ring";
+			goto fail;
+		}
+		break;
+	case '{':
+		nr_flags = NR_REG_PIPE_MASTER;
+		nr_ringid = atoi(port + 1);
+		break;
+	case '}':
+		nr_flags = NR_REG_PIPE_SLAVE;
+		nr_ringid = atoi(port + 1);
+		break;
+	}
+
+	if (nr_ringid >= NETMAP_RING_MASK) {
+		errmsg = "invalid ringid";
+		goto fail;
+	}
+	/* add the *XPOLL flags */
+	nr_ringid |= new_flags & (NETMAP_NO_TX_POLL | NETMAP_DO_RX_POLL);
+
+	d = (struct nm_desc *)calloc(1, sizeof(*d));
+	if (d == NULL) {
+		errmsg = "nm_desc alloc failure";
+		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) {
+		errmsg = "cannot open /dev/netmap";
+		goto fail;
+	}
+
+	if (req)
+		d->req = *req;
+	d->req.nr_version = NETMAP_API;
+	d->req.nr_ringid &= ~NETMAP_RING_MASK;
+
+	/* these fields are overridden by ifname and flags processing */
+	d->req.nr_ringid |= nr_ringid;
+	d->req.nr_flags = nr_flags;
+	memcpy(d->req.nr_name, ifname, namelen);
+	d->req.nr_name[namelen] = '\0';
+	/* 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 = new_flags & NM_OPEN_ARG2 ?
+			parent->req.nr_arg2 : 0;
+		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;
+		}
+	}
+	if (ioctl(d->fd, NIOCREGIF, &d->req)) {
+		errmsg = "NIOCREGIF failed";
+		goto fail;
+	}
+
+	if (IS_NETMAP_DESC(parent) && parent->mem &&
+	    parent->req.nr_arg2 == d->req.nr_arg2) {
+		/* do not mmap, inherit from parent */
+		d->memsize = parent->memsize;
+		d->mem = parent->mem;
+	} else {
+		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) {
+			errmsg = "mmap 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, );
+
+		*(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;
+	}
+
+	if (nr_flags ==  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_flags ==  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_flags ==  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_flags == NR_REG_ONE_NIC) {
+		/* XXX check validity */
+		d->first_tx_ring = d->last_tx_ring =
+		d->first_rx_ring = d->last_rx_ring = nr_ringid;
+	} else { /* pipes */
+		d->first_tx_ring = d->last_tx_ring = 0;
+		d->first_rx_ring = d->last_rx_ring = 0;
+	}
+
+#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)
+		D("%s %s", errmsg, ifname);
+	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(d, sizeof(*d));
+	free(d);
+	return 0;
+}
+
+
+/*
+ * 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;
+
+	for (c = 0; c < n ; c++) {
+		/* compute current ring to use */
+		struct netmap_ring *ring;
+		uint32_t i, idx;
+		uint32_t ri = d->cur_tx_ring + c;
+
+		if (ri > d->last_tx_ring)
+			ri = d->first_tx_ring;
+		ring = NETMAP_TXRING(d->nifp, ri);
+		if (nm_ring_empty(ring)) {
+			continue;
+		}
+		i = ring->cur;
+		idx = ring->slot[i].buf_idx;
+		ring->slot[i].len = size;
+		nm_pkt_copy(buf, NETMAP_BUF(ring, idx), size);
+		d->cur_tx_ring = ri;
+		ring->head = ring->cur = nm_ring_next(ring, i);
+		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;
+
+	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_rx_ring + c;
+		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 i = ring->cur;
+			u_int idx = ring->slot[i].buf_idx;
+			u_char *buf = (u_char *)NETMAP_BUF(ring, idx);
+
+			// __builtin_prefetch(buf);
+			d->hdr.len = d->hdr.caplen = ring->slot[i].len;
+			d->hdr.ts = ring->ts;
+			cb(arg, &d->hdr, buf);
+			ring->head = ring->cur = nm_ring_next(ring, i);
+		}
+	}
+	d->cur_rx_ring = ri;
+	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_ */