/* * Copyright (c) 1990 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. * * This code is derived from the Stanford/CMU enet packet filter, * (net/enet.c) distributed in 4.3BSD Unix. */ #ifndef lint static char rcsid[] = "$Header: bpf.c,v 1.23 91/01/30 18:22:13 mccanne Exp $"; #endif #include "bpfilter.h" #if (NBPFILTER > 0) #ifndef __GNUC__ #define inline #endif #include #include #include #include #include #include #include #include #include #include #ifdef sparc #include #endif #include #include #include #include #include #include #include #include #include #include #include #define PRINET 26 /* interruptible */ /* * 'bpf_iftab' is the driver state table per logical unit number * 'bpf_dtab' holds the descriptors, indexed by minor device # * 'bpf_units' is the number of attached units * * We really don't need NBPFILTER bpf_if entries, but this eliminates * the need to account for all possible drivers here. * This problem will go away when these structures are allocated dynamically. */ static struct bpf_if bpf_iftab[NBPFILTER]; static struct bpf_d bpf_dtab[NBPFILTER]; static u_int bpf_units = 0; static int bpf_timeout(); static void bpf_ifname(); static void catchpacket(); static int bpf_setif(); static int bpf_initd(); /* * The default filter accepts the maximum number of bytes from each packet. */ struct bpf_insn bpf_default_filter[] = { BPF_STMT(RetOp, MCLBYTES), }; /* * This routine was inspired by/stolen from ../sys/uipc_socket.c * Move data from 'm' to user's read buffer. * We assume 'm' is not chained. * Returns error code (or 0 if success). */ static inline int bpf_moveout(m, uio) register struct mbuf *m; register struct uio *uio; { register int len; len = m->m_len; if (uio->uio_resid < len) len = uio->uio_resid; if (len > 0) return uiomove(mtod(m, caddr_t), len, UIO_READ, uio); return 0; } static int bpf_movein(uio, linktype, mp, sockp) register struct uio *uio; int linktype; register struct mbuf **mp; register struct sockaddr *sockp; { struct mbuf *m; int error; int len; int hlen; /* * Build a sockaddr based on the data link layer type. * We do this at this level because the ethernet header * is copied directly into the data field of the sockaddr. * In the case of SLIP, there is no header and the packet * is forwarded as is. * Also, we are careful to leave room at the front of the mbuf * for the link level header. */ switch (linktype) { case DLT_SLIP: sockp->sa_family = AF_INET; hlen = 0; break; case DLT_EN10MB: sockp->sa_family = AF_UNSPEC; /* XXX Would MAXLINKHDR be better? */ hlen = sizeof(struct ether_header); break; case DLT_FDDI: sockp->sa_family = AF_UNSPEC; /* XXX 4(FORMAC)+6(dst)+6(src)+3(LLC)+5(SNAP) */ hlen = 24; break; default: return EIO; } len = uio->uio_resid; if ((unsigned)len > MCLBYTES) return EIO; MGET(m, M_WAIT, MT_DATA); if (m == 0) return ENOBUFS; if (len > MLEN) { MCLGET(m); if (m->m_len != MCLBYTES) { error = ENOBUFS; goto bad; } } m->m_len = len; *mp = m; /* * Make room for link header. */ if (hlen) { m->m_len -= hlen; m->m_off += hlen; error = uiomove((caddr_t)sockp->sa_data, hlen, UIO_WRITE, uio); if (error) goto bad; } error = uiomove(mtod(m, caddr_t), len - hlen, UIO_WRITE, uio); if (!error) return 0; bad: m_freem(m); return error; } /* * Attach 'd' to the bpf interface 'bp', i.e. make 'd' listen on 'bp'. * Must be called at splimp. */ static void bpf_attachd(d, bp) struct bpf_d *d; struct bpf_if *bp; { /* Point 'd' at 'bp'. */ d->bd_bif = bp; /* Add 'd' to 'bp's list of listeners. */ d->bd_next = bp->bif_dlist; bp->bif_dlist = d; /* * Let the driver know we're here (if it doesn't already). */ *bp->bif_driverp = bp; } static void bpf_detachd(d) struct bpf_d *d; { struct bpf_d **p; struct bpf_if *bp; bp = d->bd_bif; /* * Check if this descriptor had requested promiscuous mode. * If so, turn it off. */ if (d->bd_promisc) { d->bd_promisc = 0; if (ifpromisc(bp->bif_ifp, 0)) /* * Something is really wrong if we were able to put * the driver into promiscuous mode, but can't * take it out. */ panic("bpf_detachd: exit promisc unsucessful"); } /* Remove 'd' from the interface's descriptor list. */ p = &bp->bif_dlist; while (*p != d) { p = &(*p)->bd_next; if (*p == 0) panic("bpf_detachd: descriptor not in list"); } *p = (*p)->bd_next; if (bp->bif_dlist == 0) /* * Let the driver know that there are no more listeners. */ *d->bd_bif->bif_driverp = 0; d->bd_bif = 0; } /* * Mark a descriptor free by making it point to itself. * This is probably cheaper than marking with a constant since * the address should be in a register anyway. */ #define D_ISFREE(d) ((d) == (d)->bd_next) #define D_MARKFREE(d) ((d)->bd_next = (d)) #define D_MARKUSED(d) ((d)->bd_next = 0) /* * bpfopen - open ethernet device * * Errors: ENXIO - illegal minor device number * EBUSY - too many files open */ /* ARGSUSED */ int bpfopen(dev, flag) dev_t dev; int flag; { int error, s; register struct bpf_d *d; if (minor(dev) >= NBPFILTER) return ENXIO; /* * Each minor can be opened by only one process. If the requested * minor is in use, return EBUSY. */ s = splimp(); d = &bpf_dtab[minor(dev)]; if (!D_ISFREE(d)) { splx(s); return EBUSY; } else /* Mark "free" and do most initialization. */ bzero((char *)d, sizeof(*d)); d->bd_filter = bpf_default_filter; splx(s); error = bpf_initd(d); if (error) { D_MARKFREE(d); return error; } return 0; } /* * Close the descriptor by detaching it from its interface, * deallocating its buffers, and marking it free. */ /* ARGSUSED */ bpfclose(dev, flag) dev_t dev; int flag; { register struct bpf_d *d = &bpf_dtab[minor(dev)]; int s; s = splimp(); if (d->bd_bif) bpf_detachd(d); splx(s); /* Let the buffers go. */ m_freem(d->bd_hbuf); m_freem(d->bd_sbuf); m_freem(d->bd_fbuf); m_freem(d->bd_filterm); D_MARKFREE(d); } #define RS_IDLE 0 #define RS_WAIT 1 #define RS_TIMEDOUT 2 /* * bpfread - read next chunk of packets from buffers */ int bpfread(dev, uio) dev_t dev; register struct uio *uio; { register struct bpf_d *d = &bpf_dtab[minor(dev)]; struct mbuf *m; int error; int s; /* * Restrict application to use a buffer the same size as * as kernel buffers. */ if (uio->uio_resid != MCLBYTES) return EIO; s = splimp(); /* * If the hold buffer is empty, then set a timer and sleep * until either the timeout has occurred or enough packets have * arrived to fill the store buffer. */ while (d->bd_hbuf == 0) { if (d->bd_immediate && d->bd_sbuf->m_len) { /* * A packet(s) either arrived since the previous * read or arrived while we were asleep. * Rotate the buffers and return what's here. */ d->bd_hbuf = d->bd_sbuf; d->bd_sbuf = d->bd_fbuf; d->bd_sbuf->m_len = 0; d->bd_fbuf = 0; break; } if (d->bd_rtout) { /* * If there was a previous timeout pending for this * file, cancel it before setting another. This is * necessary since a cancel after the sleep might * never happen if the read is interrupted by a signal. */ if (d->bd_state == RS_WAIT) untimeout(bpf_timeout, (caddr_t)d); timeout(bpf_timeout, (caddr_t)d, (int)d->bd_rtout); d->bd_state = RS_WAIT; } else d->bd_state = RS_IDLE; sleep((caddr_t)d, PRINET); if (d->bd_state == RS_WAIT) { untimeout(bpf_timeout, (caddr_t)d); d->bd_state = RS_IDLE; } else if (d->bd_state == RS_TIMEDOUT) { /* * On a timeout, return what's in the buffer, * which may be nothing. We do this by moving * the store buffer into the hold slot. */ if (d->bd_hbuf) /* * We filled up the buffer in between * getting the timeout and arriving * here, so we don't need to rotate. */ break; if (d->bd_sbuf->m_len == 0) { splx(s); return(0); } d->bd_hbuf = d->bd_sbuf; d->bd_sbuf = d->bd_fbuf; d->bd_sbuf->m_len = 0; d->bd_fbuf = 0; break; } } /* * At this point, we know we have something in the hold slot. */ m = d->bd_hbuf; splx(s); /* * Move data from hold buffer into user space. * We know the entire buffer is transferred since * we checked above that the read buffer is MCLBYTES. */ error = bpf_moveout(m, uio); s = splimp(); if (d->bd_fbuf != 0) panic("bpfread: free mbuf slot occupied"); d->bd_fbuf = m; d->bd_hbuf = (struct mbuf *)0; splx(s); return error; } /* * If there are processes select sleeping on this descriptor, * wake them up. */ static inline void bpf_wakeup(d) register struct bpf_d *d; { if (d->bd_SelProc) { selwakeup(d->bd_SelProc, (int)d->bd_SelColl); d->bd_SelColl = 0; d->bd_SelProc = 0; } } /* * bpf_timeout - process ethernet read timeout */ static int bpf_timeout(d) register struct bpf_d * d; { register int s = splimp(); d->bd_state = RS_TIMEDOUT; wakeup((caddr_t)d); bpf_wakeup(d); splx(s); } int bpfwrite(dev, uio) dev_t dev; struct uio *uio; { register struct bpf_d *d = &bpf_dtab[minor(dev)]; struct ifnet *ifp; struct mbuf *m; int error, s; static struct sockaddr dst; if (d->bd_bif == 0) return ENXIO; ifp = d->bd_bif->bif_ifp; if (uio->uio_resid == 0) return 0; if (uio->uio_resid > ifp->if_mtu) return EMSGSIZE; error = bpf_movein(uio, (int)d->bd_bif->bif_devp.bdev_type, &m, &dst); if (error) return error; s = splnet(); error = (*ifp->if_output)(ifp, m, &dst); splx(s); /* * The driver frees the mbuf. */ return error; } /* * Reset a descriptor by flushing its packet before * and clearing the receive and drop counts. Should * be called at splimp. */ static void reset_d(d) struct bpf_d *d; { if (d->bd_hbuf) { /* Free the hold buffer. */ d->bd_fbuf = d->bd_hbuf; d->bd_hbuf = 0; } d->bd_sbuf->m_len = 0; d->bd_rcount = 0; d->bd_dcount = 0; } /* * bpfioctl - packet filter control * * FIONREAD Check for read packet available. * SIOCGIFADDR Get interface address - convenient hook to driver. * BIOCGFLEN Get max filter len. * BIOCGBLEN Get buffer len [for read()]. * BIOCSETF Set ethernet read filter. * BIOCFLUSH Flush read packet buffer. * BIOCPROMISC Put interface into promiscuous mode. * BIOCDEVP Get device parameters. * BIOCGETIF Get interface name. * BIOCSETIF Set interface. * BIOCSRTIMEOUT Set read timeout. * BIOCGRTIMEOUT Get read timeout. * BIOCGSTATS Get packet stats. * BIOCIMMEDIATE Set immediate mode. */ /* ARGSUSED */ int bpfioctl(dev, cmd, addr, flag) dev_t dev; int cmd; caddr_t addr; int flag; { register struct bpf_d *d = &bpf_dtab[minor(dev)]; int s, error = 0; switch (cmd) { default: error = EINVAL; break; /* * Check for read packet available. */ case FIONREAD: { int n; s = splimp(); n = d->bd_sbuf->m_len; if (d->bd_hbuf) n += d->bd_hbuf->m_len; splx(s); *(int *)addr = n; break; } case SIOCGIFADDR: { struct ifnet *ifp; if (d->bd_bif == 0) error = EINVAL; else { ifp = d->bd_bif->bif_ifp; error = (*ifp->if_ioctl)(ifp, cmd, addr); } break; } /* * Get max filter len. */ case BIOCGFLEN: *(u_int *)addr = MCLBYTES / sizeof(struct bpf_insn); break; /* * Get buffer len [for read()]. */ case BIOCGBLEN: *(u_int *)addr = MCLBYTES; break; /* * Set ethernet 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) { d->bd_promisc = 1; error = ifpromisc(d->bd_bif->bif_ifp, 1); } splx(s); break; /* * Get device parameters. */ case BIOCDEVP: if (d->bd_bif == 0) error = EINVAL; else *(struct bpf_devp *)addr = d->bd_bif->bif_devp; 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; } return error; } /* * Set d's packet filter program to 'fp'. If 'd' already has a filter, * free it and replace it. Returns an appropriate ioctl error code. */ int bpf_setf(d, fp) struct bpf_d *d; struct bpf_program *fp; { struct bpf_insn *fcode; struct mbuf *m; u_int flen, size; int s; if (fp->bf_insns == 0) { s = splimp(); if (fp->bf_len != 0) return EINVAL; if (d->bd_filterm) m_freem(d->bd_filterm); d->bd_filterm = 0; d->bd_filter = bpf_default_filter; reset_d(d); splx(s); return 0; } flen = fp->bf_len; size = flen * sizeof(*fp->bf_insns); if (size > MCLBYTES) return EINVAL; MGET(m, M_DONTWAIT, MT_DATA); if (m == 0) return ENOBUFS; if (size > MLEN) { MCLGET(m); if (m->m_len != MCLBYTES) { m_freem(m); return ENOBUFS; } } fcode = mtod(m, struct bpf_insn *); if (copyin((caddr_t)(fp->bf_insns), (caddr_t)fcode, size)) return EINVAL; if (bpf_validate(fcode, (int)flen)) { s = splimp(); if (d->bd_filterm) m_freem(d->bd_filterm); d->bd_filterm = m; d->bd_filter = fcode; reset_d(d); splx(s); return 0; } m_freem(m); return EINVAL; } /* * Detach 'd' from its current interface (if attached at all) and attach to * the interface named 'name'. Return ioctl error code or 0. */ static int bpf_setif(d, ifr) struct bpf_d *d; struct ifreq *ifr; { struct bpf_if *bp; char *cp; int unit, i, s; /* * 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. */ 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. */ bp = bpf_iftab; for (i = 0; i < NBPFILTER; ++bp, ++i) { 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 we're * already attached to it, just flush the buffer. * If it's not up, return an error. */ if ((ifp->if_flags & IFF_UP) == 0) return ENETDOWN; 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; } /* * Lookup the name of the 'ifp' interface and return it in 'ifr->ifr_name'. * We augment the ifp's base name with its unit number. */ 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++) ; /* Assume that unit number is less than 10. */ *d++ = ifp->if_unit + '0'; *d = '\0'; } /* * Support for select() system call * Inspired by the code in tty.c for the same purpose. * * bpfselect - returns true iff the specific operation * will not block indefinitely. Otherwise, return * false but make a note that a selwakeup() must be done. */ int bpfselect(dev, rw) register dev_t dev; int rw; { 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_sbuf->m_len || d->bd_hbuf && d->bd_hbuf->m_len) { /* * There is data waiting. */ splx(s); return 1; } /* * 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 = u.u_procp; splx(s); return 0; } /* * bpf_tap - incoming linkage from device drivers */ void bpf_tap(arg, pbuf, plen) caddr_t arg; register u_char *pbuf; register u_int plen; { struct bpf_if *bp; register struct bpf_d *d; register u_int slen; extern bcopy(); /* * 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, pbuf, plen, plen); if (slen != 0) catchpacket(d, pbuf, plen, slen, (void (*)())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_m_copydata(src, dst, len) u_char *src; u_char *dst; register int len; { register struct mbuf *m = (struct mbuf *)src; register unsigned count; while (len > 0) { if (m == 0) panic("bpf_m_copydata"); count = MIN(m->m_len, len); (void)bcopy(mtod(m, caddr_t), (caddr_t)dst, count); len -= count; dst += count; m = m->m_next; } } /* * Length of ethernet and TCP/IP header header with no IP options. */ #define BPF_MIN_SNAPLEN 50 /* * bpf_mtap - incoming linkage from device drivers, when packet * is in an mbuf chain */ void bpf_mtap(arg, m0) caddr_t arg; struct mbuf *m0; { static u_char buf[BPF_MIN_SNAPLEN]; struct bpf_if *bp = (struct bpf_if *)arg; struct bpf_d *d; u_char *cp; u_int slen, plen; int nbytes; struct mbuf *m; if (m0->m_len >= BPF_MIN_SNAPLEN) { slen = m0->m_len; cp = mtod(m0, u_char *); } else { nbytes = BPF_MIN_SNAPLEN; cp = buf; m = m0; while (m && nbytes > 0) { slen = MIN(m->m_len, nbytes); bcopy(mtod(m, char *), (char *)cp, slen); cp += slen; nbytes -= slen; m = m->m_next; } if (nbytes > 0) /* Packet too small? */ return; slen = BPF_MIN_SNAPLEN; cp = buf; } plen = 0; m = m0; while (m) { plen += m->m_len; m = m->m_next; } for (d = bp->bif_dlist; d != 0; d = d->bd_next) { ++d->bd_rcount; slen = bpf_filter(d->bd_filter, cp, plen, slen); if (slen != 0) catchpacket(d, (u_char *)m0, plen, slen, bpf_m_copydata); } } /* * Move the packet data from interface memory ('pbuf') 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_m_copydata' is passed in to copy mbuf chains. In the latter * case, 'pbuf' is really an mbuf. */ static void catchpacket(d, pbuf, plen, snaplen, cpfn) struct bpf_d *d; u_char *pbuf; u_int plen, snaplen; void (*cpfn)(); { struct mbuf *m; struct bpf_hdr *hp; int totlen, curlen; 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 cluster limit). */ if (snaplen <= plen) totlen = snaplen + hdrlen; else { totlen = plen + hdrlen; if (totlen > MCLBYTES) totlen = MCLBYTES; } m = d->bd_sbuf; /* * Round up the end of the previous packet to the next longword. */ curlen = BPF_WORDALIGN(m->m_len); if (curlen + totlen > MCLBYTES) { /* * This packet will overflow the storage buffer. * Move the current cluster buffer to the hold slot, * and grab the free one. */ if (d->bd_fbuf == 0) { /* * We haven't completed the previous read yet? * Drop the packet. */ ++d->bd_dcount; return; } /* * Rotate the buffers. Move the 'store' buffer * into the 'hold' slot, and the 'free' buffer * into the 'store' slot. Zero out the length of * the new 'store' buffer. */ d->bd_hbuf = d->bd_sbuf; m = d->bd_sbuf = d->bd_fbuf; d->bd_fbuf = 0; curlen = m->m_len = 0; /* * Wake up anyone sleeping on this descriptor. */ wakeup((caddr_t)d); bpf_wakeup(d); } else if (d->bd_immediate) { /* * Immediate mode is set. A packet arrived so any * reads should be woken up. */ wakeup((caddr_t)d); bpf_wakeup(d); } /* * Append the bpf header. */ hp = (struct bpf_hdr *)(mtod(m, u_char *) + curlen); #ifdef sun uniqtime(&hp->bh_tstamp); #else #ifdef hp300 microtime(&hp->bh_tstamp); #else hp->bh_tstamp = time; #endif #endif hp->bh_datalen = plen; hp->bh_hdrlen = hdrlen; /* * Copy the packet data into the 'store' buffer and * update the cluster length. */ (*cpfn)(pbuf, (u_char *)hp + hdrlen, hp->bh_caplen = totlen - hdrlen); m->m_len = curlen + totlen; } /* * Allocate an mbuf cluster and clear its length field. * If resources unavaiable, return 0. * We can wait in MGET since we assume that we are called * at a low priority. */ static struct mbuf * bpf_mcluster() { struct mbuf *m; MGET(m, M_WAIT, MT_DATA); if (m == 0) return 0; MCLGET(m); if (m->m_len == MCLBYTES) { m->m_len = 0; return m; } m_freem(m); return 0; } /* * Initialize all nonzero fields of a descriptor. */ static int bpf_initd(d) register struct bpf_d *d; { struct mbuf *m; /* Get the buffer space. */ m = bpf_mcluster(); if (m == 0) return ENOBUFS; d->bd_fbuf = m; m = bpf_mcluster(); if (m == 0) { m_freem(d->bd_fbuf); return ENOBUFS; } d->bd_sbuf = m; return 0; } /* * Register 'ifp' with bpf. 'devp' is the link-level device descriptor * and 'driverp' is a pointer to the 'struct bpf_if *' in the driver's softc. */ void bpfattach(driverp, ifp, devp) caddr_t *driverp; struct ifnet *ifp; struct bpf_devp *devp; { struct bpf_if *bp; int i; if (bpf_units >= NBPFILTER) { printf("bpf: too many interfaces: %s%d not attached\n", ifp->if_name, ifp->if_unit); return; } bp = &bpf_iftab[bpf_units++]; bp->bif_dlist = 0; bp->bif_driverp = (struct bpf_if **)driverp; bp->bif_ifp = ifp; bp->bif_devp = *devp; /* * 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). */ i = devp->bdev_hdrlen; bp->bif_hdrlen = BPF_WORDALIGN(i + SIZEOF_BPF_HDR) - i; /* * 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); } #endif (NBPFILTER > 0)