pcap-snit.c - platform/external/libpcap - Git at Google

 /*
  * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
  *	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: (1) source code distributions
  * retain the above copyright notice and this paragraph in its entirety, (2)
  * distributions including binary code include the above copyright notice and
  * this paragraph in its entirety in the documentation or other materials
  * provided with the distribution, and (3) all advertising materials mentioning
  * features or use of this software display the following acknowledgement:
  * ``This product includes software developed by the University of California,
  * Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
  * Modifications made to accommodate the new SunOS4.0 NIT facility by
  * Micky Liu, micky@cunixc.cc.columbia.edu, Columbia University in May, 1989.
  * This module now handles the STREAMS based NIT.
  */

 #ifndef lint
 static const char rcsid[] _U_ =
     "@(#) $Header: /tcpdump/master/libpcap/pcap-snit.c,v 1.72.2.1 2005/05/03 18:54:38 guy Exp $ (LBL)";
 #endif

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #include <sys/types.h>
 #include <sys/time.h>
 #include <sys/timeb.h>
 #include <sys/dir.h>
 #include <sys/fcntlcom.h>
 #include <sys/file.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/stropts.h>

 #include <net/if.h>
 #include <net/nit.h>
 #include <net/nit_if.h>
 #include <net/nit_pf.h>
 #include <net/nit_buf.h>

 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
 #include <netinet/if_ether.h>
 #include <netinet/ip_var.h>
 #include <netinet/udp.h>
 #include <netinet/udp_var.h>
 #include <netinet/tcp.h>
 #include <netinet/tcpip.h>

 #include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>

 #include "pcap-int.h"

 #ifdef HAVE_OS_PROTO_H
 #include "os-proto.h"
 #endif

 /*
  * The chunk size for NIT.  This is the amount of buffering
  * done for read calls.
  */
 #define CHUNKSIZE (2*1024)

 /*
  * The total buffer space used by NIT.
  */
 #define BUFSPACE (4*CHUNKSIZE)

 /* Forwards */
 static int nit_setflags(int, int, int, char *);

 static int
 pcap_stats_snit(pcap_t *p, struct pcap_stat *ps)
 {

 	/*
 	 * "ps_recv" counts packets handed to the filter, not packets
 	 * that passed the filter.  As filtering is done in userland,
 	 * this does not include packets dropped because we ran out
 	 * of buffer space.
 	 *
 	 * "ps_drop" counts packets dropped inside the "/dev/nit"
 	 * device because of flow control requirements or resource
 	 * exhaustion; it doesn't count packets dropped by the
 	 * interface driver, or packets dropped upstream.  As filtering
 	 * is done in userland, it counts packets regardless of whether
 	 * they would've passed the filter.
 	 *
 	 * These statistics don't include packets not yet read from the
 	 * kernel by libpcap or packets not yet read from libpcap by the
 	 * application.
 	 */
 	*ps = p->md.stat;
 	return (0);
 }

 static int
 pcap_read_snit(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 {
 	register int cc, n;
 	register struct bpf_insn *fcode = p->fcode.bf_insns;
 	register u_char *bp, *cp, *ep;
 	register struct nit_bufhdr *hdrp;
 	register struct nit_iftime *ntp;
 	register struct nit_iflen *nlp;
 	register struct nit_ifdrops *ndp;
 	register int caplen;

 	cc = p->cc;
 	if (cc == 0) {
 		cc = read(p->fd, (char *)p->buffer, p->bufsize);
 		if (cc < 0) {
 			if (errno == EWOULDBLOCK)
 				return (0);
 			snprintf(p->errbuf, sizeof(p->errbuf), "pcap_read: %s",
 				pcap_strerror(errno));
 			return (-1);
 		}
 		bp = p->buffer;
 	} else
 		bp = p->bp;

 	/*
 	 * loop through each snapshot in the chunk
 	 */
 	n = 0;
 	ep = bp + cc;
 	while (bp < ep) {
 		/*
 		 * Has "pcap_breakloop()" been called?
 		 * If so, return immediately - if we haven't read any
 		 * packets, clear the flag and return -2 to indicate
 		 * that we were told to break out of the loop, otherwise
 		 * leave the flag set, so that the *next* call will break
 		 * out of the loop without having read any packets, and
 		 * return the number of packets we've processed so far.
 		 */
 		if (p->break_loop) {
 			if (n == 0) {
 				p->break_loop = 0;
 				return (-2);
 			} else {
 				p->bp = bp;
 				p->cc = ep - bp;
 				return (n);
 			}
 		}

 		++p->md.stat.ps_recv;
 		cp = bp;

 		/* get past NIT buffer  */
 		hdrp = (struct nit_bufhdr *)cp;
 		cp += sizeof(*hdrp);

 		/* get past NIT timer   */
 		ntp = (struct nit_iftime *)cp;
 		cp += sizeof(*ntp);

 		ndp = (struct nit_ifdrops *)cp;
 		p->md.stat.ps_drop = ndp->nh_drops;
 		cp += sizeof *ndp;

 		/* get past packet len  */
 		nlp = (struct nit_iflen *)cp;
 		cp += sizeof(*nlp);

 		/* next snapshot        */
 		bp += hdrp->nhb_totlen;

 		caplen = nlp->nh_pktlen;
 		if (caplen > p->snapshot)
 			caplen = p->snapshot;

 		if (bpf_filter(fcode, cp, nlp->nh_pktlen, caplen)) {
 			struct pcap_pkthdr h;
 			h.ts = ntp->nh_timestamp;
 			h.len = nlp->nh_pktlen;
 			h.caplen = caplen;
 			(*callback)(user, &h, cp);
 			if (++n >= cnt && cnt >= 0) {
 				p->cc = ep - bp;
 				p->bp = bp;
 				return (n);
 			}
 		}
 	}
 	p->cc = 0;
 	return (n);
 }

 static int
 pcap_inject_snit(pcap_t *p, const void *buf, size_t size)
 {
 	struct strbuf ctl, data;

 	/*
 	 * XXX - can we just do
 	 *
 	ret = write(pd->f, buf, size);
 	 */
 	ctl.len = sizeof(*sa);	/* XXX - what was this? */
 	ctl.buf = (char *)sa;
 	data.buf = buf;
 	data.len = size;
 	ret = putmsg(p->fd, &ctl, &data);
 	if (ret == -1) {
 		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
 		    pcap_strerror(errno));
 		return (-1);
 	}
 	return (ret);
 }

 static int
 nit_setflags(int fd, int promisc, int to_ms, char *ebuf)
 {
 	bpf_u_int32 flags;
 	struct strioctl si;
 	struct timeval timeout;

 	si.ic_timout = INFTIM;
 	if (to_ms != 0) {
 		timeout.tv_sec = to_ms / 1000;
 		timeout.tv_usec = (to_ms * 1000) % 1000000;
 		si.ic_cmd = NIOCSTIME;
 		si.ic_len = sizeof(timeout);
 		si.ic_dp = (char *)&timeout;
 		if (ioctl(fd, I_STR, (char *)&si) < 0) {
 			snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSTIME: %s",
 			    pcap_strerror(errno));
 			return (-1);
 		}
 	}
 	flags = NI_TIMESTAMP | NI_LEN | NI_DROPS;
 	if (promisc)
 		flags |= NI_PROMISC;
 	si.ic_cmd = NIOCSFLAGS;
 	si.ic_len = sizeof(flags);
 	si.ic_dp = (char *)&flags;
 	if (ioctl(fd, I_STR, (char *)&si) < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSFLAGS: %s",
 		    pcap_strerror(errno));
 		return (-1);
 	}
 	return (0);
 }

 pcap_t *
 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
     char *ebuf)
 {
 	struct strioctl si;		/* struct for ioctl() */
 	struct ifreq ifr;		/* interface request struct */
 	int chunksize = CHUNKSIZE;
 	int fd;
 	static char dev[] = "/dev/nit";
 	register pcap_t *p;

 	p = (pcap_t *)malloc(sizeof(*p));
 	if (p == NULL) {
 		strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
 		return (NULL);
 	}

 	if (snaplen < 96)
 		/*
 		 * NIT requires a snapshot length of at least 96.
 		 */
 		snaplen = 96;

 	memset(p, 0, sizeof(*p));
 	/*
 	 * Initially try a read/write open (to allow the inject
 	 * method to work).  If that fails due to permission
 	 * issues, fall back to read-only.  This allows a
 	 * non-root user to be granted specific access to pcap
 	 * capabilities via file permissions.
 	 *
 	 * XXX - we should have an API that has a flag that
 	 * controls whether to open read-only or read-write,
 	 * so that denial of permission to send (or inability
 	 * to send, if sending packets isn't supported on
 	 * the device in question) can be indicated at open
 	 * time.
 	 */
 	p->fd = fd = open(dev, O_RDWR);
 	if (fd < 0 && errno == EACCES)
 		p->fd = fd = open(dev, O_RDONLY);
 	if (fd < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: %s", dev,
 		    pcap_strerror(errno));
 		goto bad;
 	}

 	/* arrange to get discrete messages from the STREAM and use NIT_BUF */
 	if (ioctl(fd, I_SRDOPT, (char *)RMSGD) < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "I_SRDOPT: %s",
 		    pcap_strerror(errno));
 		goto bad;
 	}
 	if (ioctl(fd, I_PUSH, "nbuf") < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "push nbuf: %s",
 		    pcap_strerror(errno));
 		goto bad;
 	}
 	/* set the chunksize */
 	si.ic_cmd = NIOCSCHUNK;
 	si.ic_timout = INFTIM;
 	si.ic_len = sizeof(chunksize);
 	si.ic_dp = (char *)&chunksize;
 	if (ioctl(fd, I_STR, (char *)&si) < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSCHUNK: %s",
 		    pcap_strerror(errno));
 		goto bad;
 	}

 	/* request the interface */
 	strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 	ifr.ifr_name[sizeof(ifr.ifr_name) - 1] = '\0';
 	si.ic_cmd = NIOCBIND;
 	si.ic_len = sizeof(ifr);
 	si.ic_dp = (char *)&ifr;
 	if (ioctl(fd, I_STR, (char *)&si) < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCBIND: %s: %s",
 			ifr.ifr_name, pcap_strerror(errno));
 		goto bad;
 	}

 	/* set the snapshot length */
 	si.ic_cmd = NIOCSSNAP;
 	si.ic_len = sizeof(snaplen);
 	si.ic_dp = (char *)&snaplen;
 	if (ioctl(fd, I_STR, (char *)&si) < 0) {
 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSSNAP: %s",
 		    pcap_strerror(errno));
 		goto bad;
 	}
 	p->snapshot = snaplen;
 	if (nit_setflags(p->fd, promisc, to_ms, ebuf) < 0)
 		goto bad;

 	(void)ioctl(fd, I_FLUSH, (char *)FLUSHR);
 	/*
 	 * NIT supports only ethernets.
 	 */
 	p->linktype = DLT_EN10MB;

 	p->bufsize = BUFSPACE;
 	p->buffer = (u_char *)malloc(p->bufsize);
 	if (p->buffer == NULL) {
 		strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
 		goto bad;
 	}

 	/*
 	 * "p->fd" is an FD for a STREAMS device, so "select()" and
 	 * "poll()" should work on it.
 	 */
 	p->selectable_fd = p->fd;

 	/*
 	 * This is (presumably) a real Ethernet capture; give it a
 	 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
 	 * that an application can let you choose it, in case you're
 	 * capturing DOCSIS traffic that a Cisco Cable Modem
 	 * Termination System is putting out onto an Ethernet (it
 	 * doesn't put an Ethernet header onto the wire, it puts raw
 	 * DOCSIS frames out on the wire inside the low-level
 	 * Ethernet framing).
 	 */
 	p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 	/*
 	 * If that fails, just leave the list empty.
 	 */
 	if (p->dlt_list != NULL) {
 		p->dlt_list[0] = DLT_EN10MB;
 		p->dlt_list[1] = DLT_DOCSIS;
 		p->dlt_count = 2;
 	}

 	p->read_op = pcap_read_snit;
 	p->inject_op = pcap_inject_snit;
 	p->setfilter_op = install_bpf_program;	/* no kernel filtering */
 	p->setdirection_op = NULL;	/* Not implemented. */
 	p->set_datalink_op = NULL;	/* can't change data link type */
 	p->getnonblock_op = pcap_getnonblock_fd;
 	p->setnonblock_op = pcap_setnonblock_fd;
 	p->stats_op = pcap_stats_snit;
 	p->close_op = pcap_close_common;

 	return (p);
  bad:
 	if (fd >= 0)
 		close(fd);
 	free(p);
 	return (NULL);
 }

 int
 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
 {
 	return (0);
 }
	/*
	* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
	* 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: (1) source code distributions
	* retain the above copyright notice and this paragraph in its entirety, (2)
	* distributions including binary code include the above copyright notice and
	* this paragraph in its entirety in the documentation or other materials
	* provided with the distribution, and (3) all advertising materials mentioning
	* features or use of this software display the following acknowledgement:
	* ``This product includes software developed by the University of California,
	* Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	*
	* Modifications made to accommodate the new SunOS4.0 NIT facility by
	* Micky Liu, micky@cunixc.cc.columbia.edu, Columbia University in May, 1989.
	* This module now handles the STREAMS based NIT.
	*/

	#ifndef lint
	static const char rcsid[] _U_ =
	"@(#) $Header: /tcpdump/master/libpcap/pcap-snit.c,v 1.72.2.1 2005/05/03 18:54:38 guy Exp $ (LBL)";
	#endif

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#include <sys/types.h>
	#include <sys/time.h>
	#include <sys/timeb.h>
	#include <sys/dir.h>
	#include <sys/fcntlcom.h>
	#include <sys/file.h>
	#include <sys/ioctl.h>
	#include <sys/socket.h>
	#include <sys/stropts.h>

	#include <net/if.h>
	#include <net/nit.h>
	#include <net/nit_if.h>
	#include <net/nit_pf.h>
	#include <net/nit_buf.h>

	#include <netinet/in.h>
	#include <netinet/in_systm.h>
	#include <netinet/ip.h>
	#include <netinet/if_ether.h>
	#include <netinet/ip_var.h>
	#include <netinet/udp.h>
	#include <netinet/udp_var.h>
	#include <netinet/tcp.h>
	#include <netinet/tcpip.h>

	#include <ctype.h>
	#include <errno.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>

	#include "pcap-int.h"

	#ifdef HAVE_OS_PROTO_H
	#include "os-proto.h"
	#endif

	/*
	* The chunk size for NIT. This is the amount of buffering
	* done for read calls.
	*/
	#define CHUNKSIZE (2*1024)

	/*
	* The total buffer space used by NIT.
	*/
	#define BUFSPACE (4*CHUNKSIZE)

	/* Forwards */
	static int nit_setflags(int, int, int, char *);

	static int
	pcap_stats_snit(pcap_t p, struct pcap_stat ps)
	{

	/*
	* "ps_recv" counts packets handed to the filter, not packets
	* that passed the filter. As filtering is done in userland,
	* this does not include packets dropped because we ran out
	* of buffer space.
	*
	* "ps_drop" counts packets dropped inside the "/dev/nit"
	* device because of flow control requirements or resource
	* exhaustion; it doesn't count packets dropped by the
	* interface driver, or packets dropped upstream. As filtering
	* is done in userland, it counts packets regardless of whether
	* they would've passed the filter.
	*
	* These statistics don't include packets not yet read from the
	* kernel by libpcap or packets not yet read from libpcap by the
	* application.
	*/
	*ps = p->md.stat;
	return (0);
	}

	static int
	pcap_read_snit(pcap_t p, int cnt, pcap_handler callback, u_char user)
	{
	register int cc, n;
	register struct bpf_insn *fcode = p->fcode.bf_insns;
	register u_char bp, cp, *ep;
	register struct nit_bufhdr *hdrp;
	register struct nit_iftime *ntp;
	register struct nit_iflen *nlp;
	register struct nit_ifdrops *ndp;
	register int caplen;

	cc = p->cc;
	if (cc == 0) {
	cc = read(p->fd, (char *)p->buffer, p->bufsize);
	if (cc < 0) {
	if (errno == EWOULDBLOCK)
	return (0);
	snprintf(p->errbuf, sizeof(p->errbuf), "pcap_read: %s",
	pcap_strerror(errno));
	return (-1);
	}
	bp = p->buffer;
	} else
	bp = p->bp;

	/*
	* loop through each snapshot in the chunk
	*/
	n = 0;
	ep = bp + cc;
	while (bp < ep) {
	/*
	* Has "pcap_breakloop()" been called?
	* If so, return immediately - if we haven't read any
	* packets, clear the flag and return -2 to indicate
	* that we were told to break out of the loop, otherwise
	* leave the flag set, so that the next call will break
	* out of the loop without having read any packets, and
	* return the number of packets we've processed so far.
	*/
	if (p->break_loop) {
	if (n == 0) {
	p->break_loop = 0;
	return (-2);
	} else {
	p->bp = bp;
	p->cc = ep - bp;
	return (n);
	}
	}

	++p->md.stat.ps_recv;
	cp = bp;

	/* get past NIT buffer */
	hdrp = (struct nit_bufhdr *)cp;
	cp += sizeof(*hdrp);

	/* get past NIT timer */
	ntp = (struct nit_iftime *)cp;
	cp += sizeof(*ntp);

	ndp = (struct nit_ifdrops *)cp;
	p->md.stat.ps_drop = ndp->nh_drops;
	cp += sizeof *ndp;

	/* get past packet len */
	nlp = (struct nit_iflen *)cp;
	cp += sizeof(*nlp);

	/* next snapshot */
	bp += hdrp->nhb_totlen;

	caplen = nlp->nh_pktlen;
	if (caplen > p->snapshot)
	caplen = p->snapshot;

	if (bpf_filter(fcode, cp, nlp->nh_pktlen, caplen)) {
	struct pcap_pkthdr h;
	h.ts = ntp->nh_timestamp;
	h.len = nlp->nh_pktlen;
	h.caplen = caplen;
	(*callback)(user, &h, cp);
	if (++n >= cnt && cnt >= 0) {
	p->cc = ep - bp;
	p->bp = bp;
	return (n);
	}
	}
	}
	p->cc = 0;
	return (n);
	}

	static int
	pcap_inject_snit(pcap_t p, const void buf, size_t size)
	{
	struct strbuf ctl, data;

	/*
	* XXX - can we just do
	*
	ret = write(pd->f, buf, size);
	*/
	ctl.len = sizeof(sa); / XXX - what was this? */
	ctl.buf = (char *)sa;
	data.buf = buf;
	data.len = size;
	ret = putmsg(p->fd, &ctl, &data);
	if (ret == -1) {
	snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
	pcap_strerror(errno));
	return (-1);
	}
	return (ret);
	}

	static int
	nit_setflags(int fd, int promisc, int to_ms, char *ebuf)
	{
	bpf_u_int32 flags;
	struct strioctl si;
	struct timeval timeout;

	si.ic_timout = INFTIM;
	if (to_ms != 0) {
	timeout.tv_sec = to_ms / 1000;
	timeout.tv_usec = (to_ms * 1000) % 1000000;
	si.ic_cmd = NIOCSTIME;
	si.ic_len = sizeof(timeout);
	si.ic_dp = (char *)&timeout;
	if (ioctl(fd, I_STR, (char *)&si) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSTIME: %s",
	pcap_strerror(errno));
	return (-1);
	}
	}
	flags = NI_TIMESTAMP \| NI_LEN \| NI_DROPS;
	if (promisc)
	flags \|= NI_PROMISC;
	si.ic_cmd = NIOCSFLAGS;
	si.ic_len = sizeof(flags);
	si.ic_dp = (char *)&flags;
	if (ioctl(fd, I_STR, (char *)&si) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSFLAGS: %s",
	pcap_strerror(errno));
	return (-1);
	}
	return (0);
	}

	pcap_t *
	pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
	char *ebuf)
	{
	struct strioctl si; /* struct for ioctl() */
	struct ifreq ifr; /* interface request struct */
	int chunksize = CHUNKSIZE;
	int fd;
	static char dev[] = "/dev/nit";
	register pcap_t *p;

	p = (pcap_t )malloc(sizeof(p));
	if (p == NULL) {
	strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
	return (NULL);
	}

	if (snaplen < 96)
	/*
	* NIT requires a snapshot length of at least 96.
	*/
	snaplen = 96;

	memset(p, 0, sizeof(*p));
	/*
	* Initially try a read/write open (to allow the inject
	* method to work). If that fails due to permission
	* issues, fall back to read-only. This allows a
	* non-root user to be granted specific access to pcap
	* capabilities via file permissions.
	*
	* XXX - we should have an API that has a flag that
	* controls whether to open read-only or read-write,
	* so that denial of permission to send (or inability
	* to send, if sending packets isn't supported on
	* the device in question) can be indicated at open
	* time.
	*/
	p->fd = fd = open(dev, O_RDWR);
	if (fd < 0 && errno == EACCES)
	p->fd = fd = open(dev, O_RDONLY);
	if (fd < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: %s", dev,
	pcap_strerror(errno));
	goto bad;
	}

	/* arrange to get discrete messages from the STREAM and use NIT_BUF */
	if (ioctl(fd, I_SRDOPT, (char *)RMSGD) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "I_SRDOPT: %s",
	pcap_strerror(errno));
	goto bad;
	}
	if (ioctl(fd, I_PUSH, "nbuf") < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "push nbuf: %s",
	pcap_strerror(errno));
	goto bad;
	}
	/* set the chunksize */
	si.ic_cmd = NIOCSCHUNK;
	si.ic_timout = INFTIM;
	si.ic_len = sizeof(chunksize);
	si.ic_dp = (char *)&chunksize;
	if (ioctl(fd, I_STR, (char *)&si) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSCHUNK: %s",
	pcap_strerror(errno));
	goto bad;
	}

	/* request the interface */
	strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
	ifr.ifr_name[sizeof(ifr.ifr_name) - 1] = '\0';
	si.ic_cmd = NIOCBIND;
	si.ic_len = sizeof(ifr);
	si.ic_dp = (char *)&ifr;
	if (ioctl(fd, I_STR, (char *)&si) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCBIND: %s: %s",
	ifr.ifr_name, pcap_strerror(errno));
	goto bad;
	}

	/* set the snapshot length */
	si.ic_cmd = NIOCSSNAP;
	si.ic_len = sizeof(snaplen);
	si.ic_dp = (char *)&snaplen;
	if (ioctl(fd, I_STR, (char *)&si) < 0) {
	snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSSNAP: %s",
	pcap_strerror(errno));
	goto bad;
	}
	p->snapshot = snaplen;
	if (nit_setflags(p->fd, promisc, to_ms, ebuf) < 0)
	goto bad;

	(void)ioctl(fd, I_FLUSH, (char *)FLUSHR);
	/*
	* NIT supports only ethernets.
	*/
	p->linktype = DLT_EN10MB;

	p->bufsize = BUFSPACE;
	p->buffer = (u_char *)malloc(p->bufsize);
	if (p->buffer == NULL) {
	strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
	goto bad;
	}

	/*
	* "p->fd" is an FD for a STREAMS device, so "select()" and
	* "poll()" should work on it.
	*/
	p->selectable_fd = p->fd;

	/*
	* This is (presumably) a real Ethernet capture; give it a
	* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
	* that an application can let you choose it, in case you're
	* capturing DOCSIS traffic that a Cisco Cable Modem
	* Termination System is putting out onto an Ethernet (it
	* doesn't put an Ethernet header onto the wire, it puts raw
	* DOCSIS frames out on the wire inside the low-level
	* Ethernet framing).
	*/
	p->dlt_list = (u_int ) malloc(sizeof(u_int) 2);
	/*
	* If that fails, just leave the list empty.
	*/
	if (p->dlt_list != NULL) {
	p->dlt_list[0] = DLT_EN10MB;
	p->dlt_list[1] = DLT_DOCSIS;
	p->dlt_count = 2;
	}

	p->read_op = pcap_read_snit;
	p->inject_op = pcap_inject_snit;
	p->setfilter_op = install_bpf_program; /* no kernel filtering */
	p->setdirection_op = NULL; /* Not implemented. */
	p->set_datalink_op = NULL; /* can't change data link type */
	p->getnonblock_op = pcap_getnonblock_fd;
	p->setnonblock_op = pcap_setnonblock_fd;
	p->stats_op = pcap_stats_snit;
	p->close_op = pcap_close_common;

	return (p);
	bad:
	if (fd >= 0)
	close(fd);
	free(p);
	return (NULL);
	}

	int
	pcap_platform_finddevs(pcap_if_t *alldevsp, char errbuf)
	{
	return (0);
	}