freebsd-dev/contrib/libpcap/pcap-bpf.c
2001-04-03 04:18:09 +00:00

388 lines
9.9 KiB
C

/*
* Copyright (c) 1993, 1994, 1995, 1996, 1998
* 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.
*/
#ifndef lint
static const char rcsid[] =
"@(#) $Header: /tcpdump/master/libpcap/pcap-bpf.c,v 1.44 2000/10/28 00:01:28 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/param.h> /* optionally get BSD define */
#include <sys/time.h>
#include <sys/timeb.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "pcap-int.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "gencode.h"
int
pcap_stats(pcap_t *p, struct pcap_stat *ps)
{
struct bpf_stat s;
if (ioctl(p->fd, BIOCGSTATS, (caddr_t)&s) < 0) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCGSTATS: %s",
pcap_strerror(errno));
return (-1);
}
ps->ps_recv = s.bs_recv;
ps->ps_drop = s.bs_drop;
return (0);
}
int
pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
int cc;
int n = 0;
register u_char *bp, *ep;
again:
cc = p->cc;
if (p->cc == 0) {
cc = read(p->fd, (char *)p->buffer, p->bufsize);
if (cc < 0) {
/* Don't choke when we get ptraced */
switch (errno) {
case EINTR:
goto again;
case EWOULDBLOCK:
return (0);
#if defined(sun) && !defined(BSD)
/*
* Due to a SunOS bug, after 2^31 bytes, the kernel
* file offset overflows and read fails with EINVAL.
* The lseek() to 0 will fix things.
*/
case EINVAL:
if (lseek(p->fd, 0L, SEEK_CUR) +
p->bufsize < 0) {
(void)lseek(p->fd, 0L, SEEK_SET);
goto again;
}
/* fall through */
#endif
}
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read: %s",
pcap_strerror(errno));
return (-1);
}
bp = p->buffer;
} else
bp = p->bp;
/*
* Loop through each packet.
*/
#define bhp ((struct bpf_hdr *)bp)
ep = bp + cc;
while (bp < ep) {
register int caplen, hdrlen;
caplen = bhp->bh_caplen;
hdrlen = bhp->bh_hdrlen;
/*
* XXX A bpf_hdr matches a pcap_pkthdr.
*/
(*callback)(user, (struct pcap_pkthdr*)bp, bp + hdrlen);
bp += BPF_WORDALIGN(caplen + hdrlen);
if (++n >= cnt && cnt > 0) {
p->bp = bp;
p->cc = ep - bp;
return (n);
}
}
#undef bhp
p->cc = 0;
return (n);
}
static inline int
bpf_open(pcap_t *p, char *errbuf)
{
int fd;
int n = 0;
char device[sizeof "/dev/bpf0000000000"];
/*
* Go through all the minors and find one that isn't in use.
*/
do {
(void)snprintf(device, sizeof(device), "/dev/bpf%d", n++);
fd = open(device, O_RDONLY);
} while (fd < 0 && errno == EBUSY);
/*
* XXX better message for all minors used
*/
if (fd < 0)
snprintf(errbuf, PCAP_ERRBUF_SIZE, "(no devices found) %s: %s",
device, pcap_strerror(errno));
return (fd);
}
pcap_t *
pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
{
int fd;
struct ifreq ifr;
struct bpf_version bv;
u_int v;
pcap_t *p;
p = (pcap_t *)malloc(sizeof(*p));
if (p == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
return (NULL);
}
memset(p, 0, sizeof(*p));
fd = bpf_open(p, ebuf);
if (fd < 0)
goto bad;
p->fd = fd;
p->snapshot = snaplen;
if (ioctl(fd, BIOCVERSION, (caddr_t)&bv) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCVERSION: %s",
pcap_strerror(errno));
goto bad;
}
if (bv.bv_major != BPF_MAJOR_VERSION ||
bv.bv_minor < BPF_MINOR_VERSION) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"kernel bpf filter out of date");
goto bad;
}
/*
* Try finding a good size for the buffer; 32768 may be too
* big, so keep cutting it in half until we find a size
* that works, or run out of sizes to try.
*
* XXX - there should be a user-accessible hook to set the
* initial buffer size.
*/
for (v = 32768; v != 0; v >>= 1) {
/* Ignore the return value - this is because the call fails
* on BPF systems that don't have kernel malloc. And if
* the call fails, it's no big deal, we just continue to
* use the standard buffer size.
*/
(void) ioctl(fd, BIOCSBLEN, (caddr_t)&v);
(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0)
break; /* that size worked; we're done */
if (errno != ENOBUFS) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s",
device, pcap_strerror(errno));
goto bad;
}
}
if (v == 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"BIOCSBLEN: %s: No buffer size worked", device);
goto bad;
}
/* Get the data link layer type. */
if (ioctl(fd, BIOCGDLT, (caddr_t)&v) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGDLT: %s",
pcap_strerror(errno));
goto bad;
}
#ifdef __OpenBSD__
switch (v) {
case DLT_LOOP:
/*
* XXX - DLT_LOOP has a network-byte-order, rather than
* a host-byte-order, AF_ value as the link-layer
* header; will the BPF code generator handle that
* correctly on little-endian machines?
*/
v = DLT_NULL;
break;
}
#endif
#if _BSDI_VERSION - 0 >= 199510
/* The SLIP and PPP link layer header changed in BSD/OS 2.1 */
switch (v) {
case DLT_SLIP:
v = DLT_SLIP_BSDOS;
break;
case DLT_PPP:
v = DLT_PPP_BSDOS;
break;
case 11: /*DLT_FR*/
v = DLT_RAW; /*XXX*/
break;
case 12: /*DLT_C_HDLC*/
v = DLT_CHDLC;
break;
}
#endif
p->linktype = v;
/* set timeout */
if (to_ms != 0) {
struct timeval to;
to.tv_sec = to_ms / 1000;
to.tv_usec = (to_ms * 1000) % 1000000;
if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s",
pcap_strerror(errno));
goto bad;
}
}
#ifdef _AIX
#ifdef BIOCIMMEDIATE
/*
* Darren Reed notes that
*
* On AIX (4.2 at least), if BIOCIMMEDIATE is not set, the
* timeout appears to be ignored and it waits until the buffer
* is filled before returning. The result of not having it
* set is almost worse than useless if your BPF filter
* is reducing things to only a few packets (i.e. one every
* second or so).
*
* so we turn BIOCIMMEDIATE mode on if this is AIX.
*
* We don't turn it on for other platforms, as that means we
* get woken up for every packet, which may not be what we want;
* in the Winter 1993 USENIX paper on BPF, they say:
*
* Since a process might want to look at every packet on a
* network and the time between packets can be only a few
* microseconds, it is not possible to do a read system call
* per packet and BPF must collect the data from several
* packets and return it as a unit when the monitoring
* application does a read.
*
* which I infer is the reason for the timeout - it means we
* wait that amount of time, in the hopes that more packets
* will arrive and we'll get them all with one read.
*
* Setting BIOCIMMEDIATE mode on FreeBSD (and probably other
* BSDs) causes the timeout to be ignored.
*
* On the other hand, some platforms (e.g., Linux) don't support
* timeouts, they just hand stuff to you as soon as it arrives;
* if that doesn't cause a problem on those platforms, it may
* be OK to have BIOCIMMEDIATE mode on BSD as well.
*
* (Note, though, that applications may depend on the read
* completing, even if no packets have arrived, when the timeout
* expires, e.g. GUI applications that have to check for input
* while waiting for packets to arrive; a non-zero timeout
* prevents "select()" from working right on FreeBSD and
* possibly other BSDs, as the timer doesn't start until a
* "read()" is done, so the timer isn't in effect if the
* application is blocked on a "select()", and the "select()"
* doesn't get woken up for a BPF device until the buffer
* fills up.)
*/
v = 1;
if (ioctl(p->fd, BIOCIMMEDIATE, &v) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCIMMEDIATE: %s",
pcap_strerror(errno));
goto bad;
}
#endif /* BIOCIMMEDIATE */
#endif /* _AIX */
if (promisc)
/* set promiscuous mode, okay if it fails */
(void)ioctl(p->fd, BIOCPROMISC, NULL);
if (ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGBLEN: %s",
pcap_strerror(errno));
goto bad;
}
p->bufsize = v;
p->buffer = (u_char *)malloc(p->bufsize);
if (p->buffer == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
goto bad;
}
return (p);
bad:
(void)close(fd);
free(p);
return (NULL);
}
int
pcap_setfilter(pcap_t *p, struct bpf_program *fp)
{
/*
* It looks that BPF code generated by gen_protochain() is not
* compatible with some of kernel BPF code (for example BSD/OS 3.1).
* Take a safer side for now.
*/
if (no_optimize) {
if (install_bpf_program(p, fp) < 0)
return (-1);
} else if (p->sf.rfile != NULL) {
if (install_bpf_program(p, fp) < 0)
return (-1);
} else if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
pcap_strerror(errno));
return (-1);
}
return (0);
}