bpf.c

早期freebsd实现

		}
#endif
		break;

	/*
	 * Set link layer read filter.
	 */
	case BIOCSETF:
		error = bpf_setf(d, (struct bpf_program *)addr);
		break;

	/*
	 * Flush read packet buffer.
	 */
	case BIOCFLUSH:
		s = splimp();
		reset_d(d);
		splx(s);
		break;

	/*
	 * Put interface into promiscuous mode.
	 */
	case BIOCPROMISC:
		if (d->bd_bif == 0) {
			/*
			 * No interface attached yet.
			 */
			error = EINVAL;
			break;
		}
		s = splimp();
		if (d->bd_promisc == 0) {
			error = ifpromisc(d->bd_bif->bif_ifp, 1);
			if (error == 0)
				d->bd_promisc = 1;
		}
		splx(s);
		break;

	/*
	 * Get device parameters.
	 */
	case BIOCGDLT:
		if (d->bd_bif == 0)
			error = EINVAL;
		else
			*(u_int *)addr = d->bd_bif->bif_dlt;
		break;

	/*
	 * Set interface name.
	 */
	case BIOCGETIF:
		if (d->bd_bif == 0)
			error = EINVAL;
		else
			bpf_ifname(d->bd_bif->bif_ifp, (struct ifreq *)addr);
		break;

	/*
	 * Set interface.
	 */
	case BIOCSETIF:
		error = bpf_setif(d, (struct ifreq *)addr);
		break;

	/*
	 * Set read timeout.
	 */
	case BIOCSRTIMEOUT:
		{
			struct timeval *tv = (struct timeval *)addr;
			u_long msec;

			/* Compute number of milliseconds. */
			msec = tv->tv_sec * 1000 + tv->tv_usec / 1000;
			/* Scale milliseconds to ticks.  Assume hard
			   clock has millisecond or greater resolution
			   (i.e. tick >= 1000).  For 10ms hardclock,
			   tick/1000 = 10, so rtout<-msec/10. */
			d->bd_rtout = msec / (tick / 1000);
			break;
		}

	/*
	 * Get read timeout.
	 */
	case BIOCGRTIMEOUT:
		{
			struct timeval *tv = (struct timeval *)addr;
			u_long msec = d->bd_rtout;

			msec *= tick / 1000;
			tv->tv_sec = msec / 1000;
			tv->tv_usec = msec % 1000;
			break;
		}

	/*
	 * Get packet stats.
	 */
	case BIOCGSTATS:
		{
			struct bpf_stat *bs = (struct bpf_stat *)addr;

			bs->bs_recv = d->bd_rcount;
			bs->bs_drop = d->bd_dcount;
			break;
		}

	/*
	 * Set immediate mode.
	 */
	case BIOCIMMEDIATE:
		d->bd_immediate = *(u_int *)addr;
		break;

	case BIOCVERSION:
		{
			struct bpf_version *bv = (struct bpf_version *)addr;

			bv->bv_major = BPF_MAJOR_VERSION;
			bv->bv_minor = BPF_MINOR_VERSION;
			break;
		}
	}
	return (error);
}

/*
 * Set d's packet filter program to fp.  If this file already has a filter,
 * free it and replace it.  Returns EINVAL for bogus requests.
 */
int
bpf_setf(d, fp)
	struct bpf_d *d;
	struct bpf_program *fp;
{
	struct bpf_insn *fcode, *old;
	u_int flen, size;
	int s;

	old = d->bd_filter;
	if (fp->bf_insns == 0) {
		if (fp->bf_len != 0)
			return (EINVAL);
		s = splimp();
		d->bd_filter = 0;
		reset_d(d);
		splx(s);
		if (old != 0)
			free((caddr_t)old, M_DEVBUF);
		return (0);
	}
	flen = fp->bf_len;
	if (flen > BPF_MAXINSNS)
		return (EINVAL);

	size = flen * sizeof(*fp->bf_insns);
	fcode = (struct bpf_insn *)malloc(size, M_DEVBUF, M_WAITOK);
	if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
	    bpf_validate(fcode, (int)flen)) {
		s = splimp();
		d->bd_filter = fcode;
		reset_d(d);
		splx(s);
		if (old != 0)
			free((caddr_t)old, M_DEVBUF);

		return (0);
	}
	free((caddr_t)fcode, M_DEVBUF);
	return (EINVAL);
}

/*
 * Detach a file from its current interface (if attached at all) and attach
 * to the interface indicated by the name stored in ifr.
 * Return an errno or 0.
 */
static int
bpf_setif(d, ifr)
	struct bpf_d *d;
	struct ifreq *ifr;
{
	struct bpf_if *bp;
	char *cp;
	int unit, s, error;

	/*
	 * Separate string into name part and unit number.  Put a null
	 * byte at the end of the name part, and compute the number.
	 * If the a unit number is unspecified, the default is 0,
	 * as initialized above.  XXX This should be common code.
	 */
	unit = 0;
	cp = ifr->ifr_name;
	cp[sizeof(ifr->ifr_name) - 1] = '\0';
	while (*cp++) {
		if (*cp >= '0' && *cp <= '9') {
			unit = *cp - '0';
			*cp++ = '\0';
			while (*cp)
				unit = 10 * unit + *cp++ - '0';
			break;
		}
	}
	/*
	 * Look through attached interfaces for the named one.
	 */
	for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
		struct ifnet *ifp = bp->bif_ifp;

		if (ifp == 0 || unit != ifp->if_unit
		    || strcmp(ifp->if_name, ifr->ifr_name) != 0)
			continue;
		/*
		 * We found the requested interface.
		 * If it's not up, return an error.
		 * Allocate the packet buffers if we need to.
		 * If we're already attached to requested interface,
		 * just flush the buffer.
		 */
		if ((ifp->if_flags & IFF_UP) == 0)
			return (ENETDOWN);

		if (d->bd_sbuf == 0) {
			error = bpf_allocbufs(d);
			if (error != 0)
				return (error);
		}
		s = splimp();
		if (bp != d->bd_bif) {
			if (d->bd_bif)
				/*
				 * Detach if attached to something else.
				 */
				bpf_detachd(d);

			bpf_attachd(d, bp);
		}
		reset_d(d);
		splx(s);
		return (0);
	}
	/* Not found. */
	return (ENXIO);
}

/*
 * Convert an interface name plus unit number of an ifp to a single
 * name which is returned in the ifr.
 */
static void
bpf_ifname(ifp, ifr)
	struct ifnet *ifp;
	struct ifreq *ifr;
{
	char *s = ifp->if_name;
	char *d = ifr->ifr_name;

	while (*d++ = *s++)
		continue;
	/* XXX Assume that unit number is less than 10. */
	*d++ = ifp->if_unit + '0';
	*d = '\0';
}

/*
 * The new select interface passes down the proc pointer; the old select
 * stubs had to grab it out of the user struct.  This glue allows either case.
 */
#if BSD >= 199103
#define bpf_select bpfselect
#else
int
bpfselect(dev, rw)
	register dev_t dev;
	int rw;
{
	return (bpf_select(dev, rw, u.u_procp));
}
#endif

/*
 * Support for select() system call
 *
 * Return true iff the specific operation will not block indefinitely.
 * Otherwise, return false but make a note that a selwakeup() must be done.
 */
int
bpf_select(dev, rw, p)
	register dev_t dev;
	int rw;
	struct proc *p;
{
	register struct bpf_d *d;
	register int s;

	if (rw != FREAD)
		return (0);
	/*
	 * An imitation of the FIONREAD ioctl code.
	 */
	d = &bpf_dtab[minor(dev)];

	s = splimp();
	if (d->bd_hlen != 0 || (d->bd_immediate && d->bd_slen != 0)) {
		/*
		 * There is data waiting.
		 */
		splx(s);
		return (1);
	}
#if BSD >= 199103
	selrecord(p, &d->bd_sel);
#else
	/*
	 * No data ready.  If there's already a select() waiting on this
	 * minor device then this is a collision.  This shouldn't happen
	 * because minors really should not be shared, but if a process
	 * forks while one of these is open, it is possible that both
	 * processes could select on the same descriptor.
	 */
	if (d->bd_selproc && d->bd_selproc->p_wchan == (caddr_t)&selwait)
		d->bd_selcoll = 1;
	else
		d->bd_selproc = p;
#endif
	splx(s);
	return (0);
}

/*
 * Incoming linkage from device drivers.  Process the packet pkt, of length
 * pktlen, which is stored in a contiguous buffer.  The packet is parsed
 * by each process' filter, and if accepted, stashed into the corresponding
 * buffer.
 */
void
bpf_tap(arg, pkt, pktlen)
	caddr_t arg;
	register u_char *pkt;
	register u_int pktlen;
{
	struct bpf_if *bp;
	register struct bpf_d *d;
	register u_int slen;
	/*
	 * Note that the ipl does not have to be raised at this point.
	 * The only problem that could arise here is that if two different
	 * interfaces shared any data.  This is not the case.
	 */
	bp = (struct bpf_if *)arg;
	for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
		++d->bd_rcount;
		slen = bpf_filter(d->bd_filter, pkt, pktlen, pktlen);
		if (slen != 0)
			catchpacket(d, pkt, pktlen, slen, bcopy);
	}
}

/*
 * Copy data from an mbuf chain into a buffer.  This code is derived
 * from m_copydata in sys/uipc_mbuf.c.
 */
static void
bpf_mcopy(src_arg, dst_arg, len)
	const void *src_arg;
	void *dst_arg;
	register u_int len;
{
	register const struct mbuf *m;
	register u_int count;
	u_char *dst;

	m = src_arg;
	dst = dst_arg;
	while (len > 0) {
		if (m == 0)
			panic("bpf_mcopy");
		count = min(m->m_len, len);
		bcopy(mtod(m, caddr_t), (caddr_t)dst, count);
		m = m->m_next;
		dst += count;
		len -= count;
	}
}

/*
 * Incoming linkage from device drivers, when packet is in an mbuf chain.
 */
void
bpf_mtap(arg, m)
	caddr_t arg;
	struct mbuf *m;
{
	struct bpf_if *bp = (struct bpf_if *)arg;
	struct bpf_d *d;
	u_int pktlen, slen;
	struct mbuf *m0;

	pktlen = 0;
	for (m0 = m; m0 != 0; m0 = m0->m_next)
		pktlen += m0->m_len;

	for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
		++d->bd_rcount;
		slen = bpf_filter(d->bd_filter, (u_char *)m, pktlen, 0);
		if (slen != 0)
			catchpacket(d, (u_char *)m, pktlen, slen, bpf_mcopy);
	}
}

/*
 * Move the packet data from interface memory (pkt) into the
 * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
 * otherwise 0.  "copy" is the routine called to do the actual data
 * transfer.  bcopy is passed in to copy contiguous chunks, while
 * bpf_mcopy is passed in to copy mbuf chains.  In the latter case,
 * pkt is really an mbuf.
 */
static void
catchpacket(d, pkt, pktlen, snaplen, cpfn)
	register struct bpf_d *d;
	register u_char *pkt;
	register u_int pktlen, snaplen;
	register void (*cpfn)(const void *, void *, u_int);
{
	register struct bpf_hdr *hp;
	register int totlen, curlen;
	register int hdrlen = d->bd_bif->bif_hdrlen;
	/*
	 * Figure out how many bytes to move.  If the packet is
	 * greater or equal to the snapshot length, transfer that
	 * much.  Otherwise, transfer the whole packet (unless
	 * we hit the buffer size limit).
	 */
	totlen = hdrlen + min(snaplen, pktlen);
	if (totlen > d->bd_bufsize)
		totlen = d->bd_bufsize;

	/*
	 * Round up the end of the previous packet to the next longword.
	 */
	curlen = BPF_WORDALIGN(d->bd_slen);
	if (curlen + totlen > d->bd_bufsize) {
		/*
		 * This packet will overflow the storage buffer.
		 * Rotate the buffers if we can, then wakeup any
		 * pending reads.
		 */
		if (d->bd_fbuf == 0) {
			/*
			 * We haven't completed the previous read yet,
			 * so drop the packet.
			 */
			++d->bd_dcount;
			return;
		}
		ROTATE_BUFFERS(d);
		bpf_wakeup(d);
		curlen = 0;
	}
	else if (d->bd_immediate)
		/*
		 * Immediate mode is set.  A packet arrived so any
		 * reads should be woken up.
		 */
		bpf_wakeup(d);

	/*
	 * Append the bpf header.
	 */
	hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
#if BSD >= 199103
	microtime(&hp->bh_tstamp);
#elif defined(sun)
	uniqtime(&hp->bh_tstamp);
#else
	hp->bh_tstamp = time;
#endif
	hp->bh_datalen = pktlen;
	hp->bh_hdrlen = hdrlen;
	/*
	 * Copy the packet data into the store buffer and update its length.
	 */
	(*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = totlen - hdrlen));
	d->bd_slen = curlen + totlen;
}

/*
 * Initialize all nonzero fields of a descriptor.
 */
static int
bpf_allocbufs(d)
	register struct bpf_d *d;
{
	d->bd_fbuf = (caddr_t)malloc(d->bd_bufsize, M_DEVBUF, M_WAITOK);
	if (d->bd_fbuf == 0)
		return (ENOBUFS);

	d->bd_sbuf = (caddr_t)malloc(d->bd_bufsize, M_DEVBUF, M_WAITOK);
	if (d->bd_sbuf == 0) {
		free(d->bd_fbuf, M_DEVBUF);
		return (ENOBUFS);
	}
	d->bd_slen = 0;
	d->bd_hlen = 0;
	return (0);
}

/*
 * Free buffers currently in use by a descriptor.
 * Called on close.
 */
static void
bpf_freed(d)
	register struct bpf_d *d;
{
	/*
	 * We don't need to lock out interrupts since this descriptor has
	 * been detached from its interface and it yet hasn't been marked
	 * free.
	 */
	if (d->bd_sbuf != 0) {
		free(d->bd_sbuf, M_DEVBUF);
		if (d->bd_hbuf != 0)
			free(d->bd_hbuf, M_DEVBUF);
		if (d->bd_fbuf != 0)
			free(d->bd_fbuf, M_DEVBUF);
	}
	if (d->bd_filter)
		free((caddr_t)d->bd_filter, M_DEVBUF);

	D_MARKFREE(d);
}

/*
 * Attach an interface to bpf.  driverp is a pointer to a (struct bpf_if *)
 * in the driver's softc; dlt is the link layer type; hdrlen is the fixed
 * size of the link header (variable length headers not yet supported).
 */
void
bpfattach(driverp, ifp, dlt, hdrlen)
	caddr_t *driverp;
	struct ifnet *ifp;
	u_int dlt, hdrlen;
{
	struct bpf_if *bp;
	int i;
#if BSD < 199103
	static struct bpf_if bpf_ifs[NBPFILTER];
	static int bpfifno;

	bp = (bpfifno < NBPFILTER) ? &bpf_ifs[bpfifno++] : 0;
#else
	bp = (struct bpf_if *)malloc(sizeof(*bp), M_DEVBUF, M_DONTWAIT);
#endif
	if (bp == 0)
		panic("bpfattach");

	bp->bif_dlist = 0;
	bp->bif_driverp = (struct bpf_if **)driverp;
	bp->bif_ifp = ifp;
	bp->bif_dlt = dlt;

	bp->bif_next = bpf_iflist;
	bpf_iflist = bp;

	*bp->bif_driverp = 0;

	/*
	 * Compute the length of the bpf header.  This is not necessarily
	 * equal to SIZEOF_BPF_HDR because we want to insert spacing such
	 * that the network layer header begins on a longword boundary (for
	 * performance reasons and to alleviate alignment restrictions).
	 */
	bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;

	/*
	 * Mark all the descriptors free if this hasn't been done.
	 */
	if (!D_ISFREE(&bpf_dtab[0]))
		for (i = 0; i < NBPFILTER; ++i)
			D_MARKFREE(&bpf_dtab[i]);

	printf("bpf: %s%d attached\n", ifp->if_name, ifp->if_unit);
}

#if BSD >= 199103
/* XXX This routine belongs in net/if.c. */
/*
 * Set/clear promiscuous mode on interface ifp based on the truth value
 * of pswitch.  The calls are reference counted so that only the first
 * "on" request actually has an effect, as does the final "off" request.
 * Results are undefined if the "off" and "on" requests are not matched.
 */
int
ifpromisc(ifp, pswitch)
	struct ifnet *ifp;
	int pswitch;
{
	struct ifreq ifr;
	/*
	 * If the device is not configured up, we cannot put it in
	 * promiscuous mode.
	 */
	if ((ifp->if_flags & IFF_UP) == 0)
		return (ENETDOWN);

	if (pswitch) {
		if (ifp->if_pcount++ != 0)
			return (0);
		ifp->if_flags |= IFF_PROMISC;
	} else {
		if (--ifp->if_pcount > 0)
			return (0);
		ifp->if_flags &= ~IFF_PROMISC;
	}
	ifr.ifr_flags = ifp->if_flags;
	return ((*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr));
}
#endif

#if BSD < 199103
/*
 * Allocate some memory for bpf.  This is temporary SunOS support, and
 * is admittedly a hack.
 * If resources unavaiable, return 0.
 */
static caddr_t
bpf_alloc(size, canwait)
	register int size;
	register int canwait;
{
	register struct mbuf *m;

	if ((unsigned)size > (MCLBYTES-8))
		return 0;

	MGET(m, canwait, MT_DATA);
	if (m == 0)
		return 0;
	if ((unsigned)size > (MLEN-8)) {
		MCLGET(m);
		if (m->m_len != MCLBYTES) {
			m_freem(m);
			return 0;
		}
	}
	*mtod(m, struct mbuf **) = m;
	return mtod(m, caddr_t) + 8;
}
#endif
#endif