480 lines
12 KiB
C
480 lines
12 KiB
C
/*
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* Copyright (c) 1993, 1994, 1995, 1996, 1998
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that: (1) source code distributions
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* retain the above copyright notice and this paragraph in its entirety, (2)
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* distributions including binary code include the above copyright notice and
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* this paragraph in its entirety in the documentation or other materials
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* provided with the distribution, and (3) all advertising materials mentioning
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* features or use of this software display the following acknowledgement:
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* ``This product includes software developed by the University of California,
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* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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* the University nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef lint
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static const char rcsid[] =
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"@(#) $Header: /tcpdump/master/libpcap/pcap-bpf.c,v 1.53 2002-10-08 07:18:08 guy Exp $ (LBL)";
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#endif
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <sys/param.h> /* optionally get BSD define */
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#include <sys/time.h>
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#include <sys/timeb.h>
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#include <sys/socket.h>
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#include <sys/file.h>
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#include <sys/ioctl.h>
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#include <net/if.h>
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#ifdef _AIX
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#include <net/if_types.h> /* for IFT_ values */
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#endif
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#include <ctype.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "pcap-int.h"
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#ifdef HAVE_OS_PROTO_H
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#include "os-proto.h"
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#endif
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#include "gencode.h"
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int
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pcap_stats(pcap_t *p, struct pcap_stat *ps)
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{
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struct bpf_stat s;
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/*
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* "ps_recv" counts packets handed to the filter, not packets
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* that passed the filter. This includes packets later dropped
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* because we ran out of buffer space.
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*
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* "ps_drop" counts packets dropped inside the BPF device
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* because we ran out of buffer space. It doesn't count
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* packets dropped by the interface driver. It counts
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* only packets that passed the filter.
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*
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* Both statistics include packets not yet read from the kernel
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* by libpcap, and thus not yet seen by the application.
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*/
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if (ioctl(p->fd, BIOCGSTATS, (caddr_t)&s) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCGSTATS: %s",
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pcap_strerror(errno));
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return (-1);
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}
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ps->ps_recv = s.bs_recv;
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ps->ps_drop = s.bs_drop;
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return (0);
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}
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int
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pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
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{
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int cc;
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int n = 0;
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register u_char *bp, *ep;
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again:
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cc = p->cc;
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if (p->cc == 0) {
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cc = read(p->fd, (char *)p->buffer, p->bufsize);
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if (cc < 0) {
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/* Don't choke when we get ptraced */
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switch (errno) {
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case EINTR:
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goto again;
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#ifdef _AIX
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case EFAULT:
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/*
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* Sigh. More AIX wonderfulness.
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*
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* It appears, according to Don
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* Ebright, that a read from a BPF
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* device returns -1 with "errno"
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* set to EFAULT as an indication
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* that packets have been dropped
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* since the last successful read.
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*
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* This means that we shouldn't treat
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* EFAULT as a fatal error; as we
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* don't have an API for returning
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* a "some packets were dropped since
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* the last packet you saw" indication,
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* we just ignore EFAULT and keep reading.
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*/
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goto again;
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#endif
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case EWOULDBLOCK:
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return (0);
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#if defined(sun) && !defined(BSD)
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/*
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* Due to a SunOS bug, after 2^31 bytes, the kernel
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* file offset overflows and read fails with EINVAL.
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* The lseek() to 0 will fix things.
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*/
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case EINVAL:
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if (lseek(p->fd, 0L, SEEK_CUR) +
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p->bufsize < 0) {
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(void)lseek(p->fd, 0L, SEEK_SET);
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goto again;
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}
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/* fall through */
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#endif
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}
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read: %s",
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pcap_strerror(errno));
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return (-1);
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}
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bp = p->buffer;
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} else
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bp = p->bp;
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/*
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* Loop through each packet.
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*/
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#define bhp ((struct bpf_hdr *)bp)
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ep = bp + cc;
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while (bp < ep) {
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register int caplen, hdrlen;
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caplen = bhp->bh_caplen;
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hdrlen = bhp->bh_hdrlen;
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/*
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* XXX A bpf_hdr matches a pcap_pkthdr.
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*/
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#ifdef _AIX
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/*
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* AIX's BPF returns seconds/nanoseconds time stamps, not
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* seconds/microseconds time stamps.
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*
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* XXX - I'm guessing here that it's a "struct timestamp";
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* if not, this code won't compile, but, if not, you
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* want to send us a bug report and fall back on using
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* DLPI. It's not as if BPF used to work right on
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* AIX before this change; this change attempts to fix
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* the fact that it didn't....
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*/
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bhp->bh_tstamp.tv_usec = bhp->bh_tstamp.tv_usec/1000;
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#endif
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(*callback)(user, (struct pcap_pkthdr*)bp, bp + hdrlen);
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bp += BPF_WORDALIGN(caplen + hdrlen);
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if (++n >= cnt && cnt > 0) {
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p->bp = bp;
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p->cc = ep - bp;
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return (n);
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}
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}
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#undef bhp
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p->cc = 0;
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return (n);
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}
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static inline int
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bpf_open(pcap_t *p, char *errbuf)
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{
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int fd;
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int n = 0;
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char device[sizeof "/dev/bpf0000000000"];
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/*
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* Go through all the minors and find one that isn't in use.
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*/
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do {
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(void)snprintf(device, sizeof(device), "/dev/bpf%d", n++);
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fd = open(device, O_RDONLY);
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} while (fd < 0 && errno == EBUSY);
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/*
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* XXX better message for all minors used
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*/
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if (fd < 0)
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snprintf(errbuf, PCAP_ERRBUF_SIZE, "(no devices found) %s: %s",
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device, pcap_strerror(errno));
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return (fd);
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}
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/*
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* XXX - on AIX, IBM's tcpdump (and perhaps the incompatible-with-everybody-
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* else's libpcap in AIX 5.1) appears to forcibly load the BPF driver
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* if it's not already loaded, and to create the BPF devices if they
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* don't exist.
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*
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* It'd be nice if we could do the same, although the code to do so
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* might be version-dependent, alas (the way to do it isn't necessarily
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* documented).
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*/
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pcap_t *
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pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
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{
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int fd;
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struct ifreq ifr;
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struct bpf_version bv;
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u_int v;
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pcap_t *p;
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p = (pcap_t *)malloc(sizeof(*p));
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if (p == NULL) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
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pcap_strerror(errno));
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return (NULL);
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}
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memset(p, 0, sizeof(*p));
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fd = bpf_open(p, ebuf);
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if (fd < 0)
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goto bad;
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p->fd = fd;
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p->snapshot = snaplen;
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if (ioctl(fd, BIOCVERSION, (caddr_t)&bv) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCVERSION: %s",
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pcap_strerror(errno));
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goto bad;
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}
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if (bv.bv_major != BPF_MAJOR_VERSION ||
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bv.bv_minor < BPF_MINOR_VERSION) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE,
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"kernel bpf filter out of date");
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goto bad;
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}
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/*
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* Try finding a good size for the buffer; 32768 may be too
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* big, so keep cutting it in half until we find a size
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* that works, or run out of sizes to try.
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*
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* XXX - there should be a user-accessible hook to set the
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* initial buffer size.
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*/
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for (v = 32768; v != 0; v >>= 1) {
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/* Ignore the return value - this is because the call fails
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* on BPF systems that don't have kernel malloc. And if
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* the call fails, it's no big deal, we just continue to
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* use the standard buffer size.
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*/
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(void) ioctl(fd, BIOCSBLEN, (caddr_t)&v);
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(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
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if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0)
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break; /* that size worked; we're done */
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if (errno != ENOBUFS) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s",
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device, pcap_strerror(errno));
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goto bad;
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}
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}
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if (v == 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE,
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"BIOCSBLEN: %s: No buffer size worked", device);
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goto bad;
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}
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/* Get the data link layer type. */
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if (ioctl(fd, BIOCGDLT, (caddr_t)&v) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGDLT: %s",
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pcap_strerror(errno));
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goto bad;
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}
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#ifdef _AIX
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/*
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* AIX's BPF returns IFF_ types, not DLT_ types, in BIOCGDLT.
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*/
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switch (v) {
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case IFT_ETHER:
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case IFT_ISO88023:
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v = DLT_EN10MB;
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break;
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case IFT_FDDI:
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v = DLT_FDDI;
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break;
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case IFT_ISO88025:
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v = DLT_IEEE802;
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break;
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default:
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/*
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* We don't know what to map this to yet.
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*/
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown interface type %u",
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v);
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goto bad;
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}
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#endif
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#if _BSDI_VERSION - 0 >= 199510
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/* The SLIP and PPP link layer header changed in BSD/OS 2.1 */
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switch (v) {
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case DLT_SLIP:
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v = DLT_SLIP_BSDOS;
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break;
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case DLT_PPP:
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v = DLT_PPP_BSDOS;
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break;
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case 11: /*DLT_FR*/
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v = DLT_FRELAY;
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break;
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case 12: /*DLT_C_HDLC*/
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v = DLT_CHDLC;
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break;
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}
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#endif
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p->linktype = v;
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/* set timeout */
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if (to_ms != 0) {
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/*
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* XXX - is this seconds/nanoseconds in AIX?
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* (Treating it as such doesn't fix the timeout
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* problem described below.)
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*/
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struct timeval to;
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to.tv_sec = to_ms / 1000;
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to.tv_usec = (to_ms * 1000) % 1000000;
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if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s",
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pcap_strerror(errno));
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goto bad;
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}
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}
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#ifdef _AIX
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#ifdef BIOCIMMEDIATE
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/*
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* Darren Reed notes that
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*
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* On AIX (4.2 at least), if BIOCIMMEDIATE is not set, the
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* timeout appears to be ignored and it waits until the buffer
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* is filled before returning. The result of not having it
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* set is almost worse than useless if your BPF filter
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* is reducing things to only a few packets (i.e. one every
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* second or so).
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*
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* so we turn BIOCIMMEDIATE mode on if this is AIX.
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*
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* We don't turn it on for other platforms, as that means we
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* get woken up for every packet, which may not be what we want;
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* in the Winter 1993 USENIX paper on BPF, they say:
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*
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* Since a process might want to look at every packet on a
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* network and the time between packets can be only a few
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* microseconds, it is not possible to do a read system call
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* per packet and BPF must collect the data from several
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* packets and return it as a unit when the monitoring
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* application does a read.
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*
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* which I infer is the reason for the timeout - it means we
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* wait that amount of time, in the hopes that more packets
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* will arrive and we'll get them all with one read.
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*
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* Setting BIOCIMMEDIATE mode on FreeBSD (and probably other
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* BSDs) causes the timeout to be ignored.
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*
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* On the other hand, some platforms (e.g., Linux) don't support
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* timeouts, they just hand stuff to you as soon as it arrives;
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* if that doesn't cause a problem on those platforms, it may
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* be OK to have BIOCIMMEDIATE mode on BSD as well.
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*
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* (Note, though, that applications may depend on the read
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* completing, even if no packets have arrived, when the timeout
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* expires, e.g. GUI applications that have to check for input
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* while waiting for packets to arrive; a non-zero timeout
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* prevents "select()" from working right on FreeBSD and
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* possibly other BSDs, as the timer doesn't start until a
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* "read()" is done, so the timer isn't in effect if the
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* application is blocked on a "select()", and the "select()"
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* doesn't get woken up for a BPF device until the buffer
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* fills up.)
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*/
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v = 1;
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if (ioctl(p->fd, BIOCIMMEDIATE, &v) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCIMMEDIATE: %s",
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pcap_strerror(errno));
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goto bad;
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}
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#endif /* BIOCIMMEDIATE */
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#endif /* _AIX */
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if (promisc) {
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/* set promiscuous mode, okay if it fails */
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if (ioctl(p->fd, BIOCPROMISC, NULL) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCPROMISC: %s",
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pcap_strerror(errno));
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}
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}
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if (ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGBLEN: %s",
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pcap_strerror(errno));
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goto bad;
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}
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p->bufsize = v;
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p->buffer = (u_char *)malloc(p->bufsize);
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if (p->buffer == NULL) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
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pcap_strerror(errno));
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goto bad;
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}
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return (p);
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bad:
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(void)close(fd);
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free(p);
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return (NULL);
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}
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int
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pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
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{
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return (0);
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}
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int
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pcap_setfilter(pcap_t *p, struct bpf_program *fp)
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{
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/*
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* It looks that BPF code generated by gen_protochain() is not
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* compatible with some of kernel BPF code (for example BSD/OS 3.1).
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* Take a safer side for now.
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*/
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if (no_optimize) {
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if (install_bpf_program(p, fp) < 0)
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return (-1);
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} else if (p->sf.rfile != NULL) {
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if (install_bpf_program(p, fp) < 0)
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return (-1);
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} else if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
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pcap_strerror(errno));
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return (-1);
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}
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return (0);
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}
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