NetBSD-5.0.2/dist/libpcap/pcap-bpf.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[] _U_ =
"@(#) $Header: /cvsroot/src/dist/libpcap/pcap-bpf.c,v 1.2 2006/02/27 15:51:38 drochner 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 <sys/utsname.h>
#ifdef __NetBSD__
#include <paths.h>
#endif
#include <net/if.h>
#ifdef _AIX
/*
* Make "pcap.h" not include "pcap-bpf.h"; we are going to include the
* native OS version, as we need "struct bpf_config" from it.
*/
#define PCAP_DONT_INCLUDE_PCAP_BPF_H
#include <sys/types.h>
/*
* Prevent bpf.h from redefining the DLT_ values to their
* IFT_ values, as we're going to return the standard libpcap
* values, not IBM's non-standard IFT_ values.
*/
#undef _AIX
#include <net/bpf.h>
#define _AIX
#include <net/if_types.h> /* for IFT_ values */
#include <sys/sysconfig.h>
#include <sys/device.h>
#include <sys/cfgodm.h>
#include <cf.h>
#ifdef __64BIT__
#define domakedev makedev64
#define getmajor major64
#define bpf_hdr bpf_hdr32
#else /* __64BIT__ */
#define domakedev makedev
#define getmajor major
#endif /* __64BIT__ */
#define BPF_NAME "bpf"
#define BPF_MINORS 4
#define DRIVER_PATH "/usr/lib/drivers"
#define BPF_NODE "/dev/bpf"
static int bpfloadedflag = 0;
static int odmlockid = 0;
#else /* _AIX */
#include <net/bpf.h>
#endif /* _AIX */
#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_DAG_API
#include "pcap-dag.h"
#endif /* HAVE_DAG_API */
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "gencode.h" /* for "no_optimize" */
static int pcap_setfilter_bpf(pcap_t *p, struct bpf_program *fp);
static int pcap_setdirection_bpf(pcap_t *, pcap_direction_t);
static int pcap_set_datalink_bpf(pcap_t *p, int dlt);
static int
pcap_stats_bpf(pcap_t *p, struct pcap_stat *ps)
{
struct bpf_stat s;
/*
* "ps_recv" counts packets handed to the filter, not packets
* that passed the filter. This includes packets later dropped
* because we ran out of buffer space.
*
* "ps_drop" counts packets dropped inside the BPF device
* because we ran out of buffer space. It doesn't count
* packets dropped by the interface driver. It counts
* only packets that passed the filter.
*
* Both statistics include packets not yet read from the kernel
* by libpcap, and thus not yet seen by the application.
*/
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);
}
static int
pcap_read_bpf(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
int cc;
int n = 0;
register u_char *bp, *ep;
u_char *datap;
struct bpf_insn *fcode;
#ifdef PCAP_FDDIPAD
register int pad;
#endif
fcode = p->md.use_bpf ? NULL : p->fcode.bf_insns;
again:
/*
* Has "pcap_breakloop()" been called?
*/
if (p->break_loop) {
/*
* Yes - clear the flag that indicates that it
* has, and return -2 to indicate that we were
* told to break out of the loop.
*/
p->break_loop = 0;
return (-2);
}
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;
#ifdef _AIX
case EFAULT:
/*
* Sigh. More AIX wonderfulness.
*
* For some unknown reason the uiomove()
* operation in the bpf kernel extension
* used to copy the buffer into user
* space sometimes returns EFAULT. I have
* no idea why this is the case given that
* a kernel debugger shows the user buffer
* is correct. This problem appears to
* be mostly mitigated by the memset of
* the buffer before it is first used.
* Very strange.... Shaun Clowes
*
* In any case this means that we shouldn't
* treat EFAULT as a fatal error; as we
* don't have an API for returning
* a "some packets were dropped since
* the last packet you saw" indication,
* we just ignore EFAULT and keep reading.
*/
goto again;
#endif
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;
#ifdef PCAP_FDDIPAD
pad = p->fddipad;
#endif
while (bp < ep) {
register int caplen, hdrlen;
/*
* 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);
}
}
caplen = bhp->bh_caplen;
hdrlen = bhp->bh_hdrlen;
datap = bp + hdrlen;
/*
* Short-circuit evaluation: if using BPF filter
* in kernel, no need to do it now.
*
#ifdef PCAP_FDDIPAD
* Note: the filter code was generated assuming
* that p->fddipad was the amount of padding
* before the header, as that's what's required
* in the kernel, so we run the filter before
* skipping that padding.
#endif
*/
if (fcode == NULL ||
bpf_filter(fcode, datap, bhp->bh_datalen, caplen)) {
struct pcap_pkthdr pkthdr;
pkthdr.ts.tv_sec = bhp->bh_tstamp.tv_sec;
#ifdef _AIX
/*
* AIX's BPF returns seconds/nanoseconds time
* stamps, not seconds/microseconds time stamps.
*/
pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec/1000;
#else
pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec;
#endif
#ifdef PCAP_FDDIPAD
if (caplen > pad)
pkthdr.caplen = caplen - pad;
else
pkthdr.caplen = 0;
if (bhp->bh_datalen > pad)
pkthdr.len = bhp->bh_datalen - pad;
else
pkthdr.len = 0;
datap += pad;
#else
pkthdr.caplen = caplen;
pkthdr.len = bhp->bh_datalen;
#endif
(*callback)(user, &pkthdr, datap);
bp += BPF_WORDALIGN(caplen + hdrlen);
if (++n >= cnt && cnt > 0) {
p->bp = bp;
p->cc = ep - bp;
return (n);
}
} else {
/*
* Skip this packet.
*/
bp += BPF_WORDALIGN(caplen + hdrlen);
}
}
#undef bhp
p->cc = 0;
return (n);
}
static int
pcap_inject_bpf(pcap_t *p, const void *buf, size_t size)
{
int ret;
ret = write(p->fd, buf, size);
#ifdef __APPLE__
if (ret == -1 && errno == EAFNOSUPPORT) {
/*
* In Mac OS X, there's a bug wherein setting the
* BIOCSHDRCMPLT flag causes writes to fail; see,
* for example:
*
* http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/BIOCSHDRCMPLT-10.3.3.patch
*
* So, if, on OS X, we get EAFNOSUPPORT from the write, we
* assume it's due to that bug, and turn off that flag
* and try again. If we succeed, it either means that
* somebody applied the fix from that URL, or other patches
* for that bug from
*
* http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/
*
* and are running a Darwin kernel with those fixes, or
* that Apple fixed the problem in some OS X release.
*/
u_int spoof_eth_src = 0;
if (ioctl(p->fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) {
(void)snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"send: can't turn off BIOCSHDRCMPLT: %s",
pcap_strerror(errno));
return (-1);
}
/*
* Now try the write again.
*/
ret = write(p->fd, buf, size);
}
#endif /* __APPLE__ */
if (ret == -1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
pcap_strerror(errno));
return (-1);
}
return (ret);
}
#ifdef _AIX
static int
bpf_odminit(char *errbuf)
{
char *errstr;
if (odm_initialize() == -1) {
if (odm_err_msg(odmerrno, &errstr) == -1)
errstr = "Unknown error";
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: odm_initialize failed: %s",
errstr);
return (-1);
}
if ((odmlockid = odm_lock("/etc/objrepos/config_lock", ODM_WAIT)) == -1) {
if (odm_err_msg(odmerrno, &errstr) == -1)
errstr = "Unknown error";
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: odm_lock of /etc/objrepos/config_lock failed: %s",
errstr);
return (-1);
}
return (0);
}
static int
bpf_odmcleanup(char *errbuf)
{
char *errstr;
if (odm_unlock(odmlockid) == -1) {
if (odm_err_msg(odmerrno, &errstr) == -1)
errstr = "Unknown error";
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: odm_unlock failed: %s",
errstr);
return (-1);
}
if (odm_terminate() == -1) {
if (odm_err_msg(odmerrno, &errstr) == -1)
errstr = "Unknown error";
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: odm_terminate failed: %s",
errstr);
return (-1);
}
return (0);
}
static int
bpf_load(char *errbuf)
{
long major;
int *minors;
int numminors, i, rc;
char buf[1024];
struct stat sbuf;
struct bpf_config cfg_bpf;
struct cfg_load cfg_ld;
struct cfg_kmod cfg_km;
/*
* This is very very close to what happens in the real implementation
* but I've fixed some (unlikely) bug situations.
*/
if (bpfloadedflag)
return (0);
if (bpf_odminit(errbuf) != 0)
return (-1);
major = genmajor(BPF_NAME);
if (major == -1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: genmajor failed: %s", pcap_strerror(errno));
return (-1);
}
minors = getminor(major, &numminors, BPF_NAME);
if (!minors) {
minors = genminor("bpf", major, 0, BPF_MINORS, 1, 1);
if (!minors) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: genminor failed: %s",
pcap_strerror(errno));
return (-1);
}
}
if (bpf_odmcleanup(errbuf))
return (-1);
rc = stat(BPF_NODE "0", &sbuf);
if (rc == -1 && errno != ENOENT) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: can't stat %s: %s",
BPF_NODE "0", pcap_strerror(errno));
return (-1);
}
if (rc == -1 || getmajor(sbuf.st_rdev) != major) {
for (i = 0; i < BPF_MINORS; i++) {
sprintf(buf, "%s%d", BPF_NODE, i);
unlink(buf);
if (mknod(buf, S_IRUSR | S_IFCHR, domakedev(major, i)) == -1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: can't mknod %s: %s",
buf, pcap_strerror(errno));
return (-1);
}
}
}
/* Check if the driver is loaded */
memset(&cfg_ld, 0x0, sizeof(cfg_ld));
cfg_ld.path = buf;
sprintf(cfg_ld.path, "%s/%s", DRIVER_PATH, BPF_NAME);
if ((sysconfig(SYS_QUERYLOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) ||
(cfg_ld.kmid == 0)) {
/* Driver isn't loaded, load it now */
if (sysconfig(SYS_SINGLELOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: could not load driver: %s",
strerror(errno));
return (-1);
}
}
/* Configure the driver */
cfg_km.cmd = CFG_INIT;
cfg_km.kmid = cfg_ld.kmid;
cfg_km.mdilen = sizeof(cfg_bpf);
cfg_km.mdiptr = (void *)&cfg_bpf;
for (i = 0; i < BPF_MINORS; i++) {
cfg_bpf.devno = domakedev(major, i);
if (sysconfig(SYS_CFGKMOD, (void *)&cfg_km, sizeof(cfg_km)) == -1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bpf_load: could not configure driver: %s",
strerror(errno));
return (-1);
}
}
bpfloadedflag = 1;
return (0);
}
#endif
static inline int
bpf_open(pcap_t *p, char *errbuf)
{
int fd;
#ifndef _PATH_BPF
int n = 0;
char device[sizeof "/dev/bpf0000000000"];
#else
const char *device = _PATH_BPF;
#endif
#ifdef _AIX
/*
* Load the bpf driver, if it isn't already loaded,
* and create the BPF device entries, if they don't
* already exist.
*/
if (bpf_load(errbuf) == -1)
return (-1);
#endif
#ifndef _PATH_BPF
/*
* Go through all the minors and find one that isn't in use.
*/
do {
(void)snprintf(device, sizeof(device), "/dev/bpf%d", n++);
/*
* 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.
*/
fd = open(device, O_RDWR);
if (fd == -1 && errno == EACCES)
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));
#else
if ((fd = open(device, O_RDWR)) == -1 &&
(errno != EACCES || (fd = open(device, O_RDONLY)) == -1))
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"(cannot open device) %s: %s", device, pcap_strerror(errno));
#endif
return (fd);
}
/*
* We include the OS's <net/bpf.h>, not our "pcap-bpf.h", so we probably
* don't get DLT_DOCSIS defined.
*/
#ifndef DLT_DOCSIS
#define DLT_DOCSIS 143
#endif
pcap_t *
pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
char *ebuf)
{
int fd;
struct ifreq ifr;
struct bpf_version bv;
#ifdef BIOCGDLTLIST
struct bpf_dltlist bdl;
#endif
#if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT)
u_int spoof_eth_src = 1;
#endif
u_int v;
pcap_t *p;
struct bpf_insn total_insn;
struct bpf_program total_prog;
struct utsname osinfo;
#ifdef HAVE_DAG_API
if (strstr(device, "dag")) {
return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
}
#endif /* HAVE_DAG_API */
#ifdef BIOCGDLTLIST
memset(&bdl, 0, sizeof(bdl));
#endif
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. If the default
* is larger, don't make it smaller.
*
* XXX - there should be a user-accessible hook to set the
* initial buffer size.
*/
if ((ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) || v < 32768)
v = 32768;
for ( ; 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 _AIX
/*
* AIX's BPF returns IFF_ types, not DLT_ types, in BIOCGDLT.
*/
switch (v) {
case IFT_ETHER:
case IFT_ISO88023:
v = DLT_EN10MB;
break;
case IFT_FDDI:
v = DLT_FDDI;
break;
case IFT_ISO88025:
v = DLT_IEEE802;
break;
case IFT_LOOP:
v = DLT_NULL;
break;
default:
/*
* We don't know what to map this to yet.
*/
snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown interface type %u",
v);
goto bad;
}
#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_FRELAY;
break;
case 12: /*DLT_C_HDLC*/
v = DLT_CHDLC;
break;
}
#endif
#ifdef PCAP_FDDIPAD
if (v == DLT_FDDI)
p->fddipad = PCAP_FDDIPAD;
else
p->fddipad = 0;
#endif
p->linktype = v;
#ifdef BIOCGDLTLIST
/*
* We know the default link type -- now determine all the DLTs
* this interface supports. If this fails with EINVAL, it's
* not fatal; we just don't get to use the feature later.
*/
if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) == 0) {
u_int i;
int is_ethernet;
bdl.bfl_list = (u_int *) malloc(sizeof(u_int) * bdl.bfl_len + 1);
if (bdl.bfl_list == NULL) {
(void)snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
goto bad;
}
if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) < 0) {
(void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
"BIOCGDLTLIST: %s", pcap_strerror(errno));
free(bdl.bfl_list);
goto bad;
}
/*
* OK, for real Ethernet devices, add DLT_DOCSIS to the
* list, 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).
*
* A "real Ethernet device" is defined here as a device
* that has a link-layer type of DLT_EN10MB and that has
* no alternate link-layer types; that's done to exclude
* 802.11 interfaces (which might or might not be the
* right thing to do, but I suspect it is - Ethernet <->
* 802.11 bridges would probably badly mishandle frames
* that don't have Ethernet headers).
*/
if (p->linktype == DLT_EN10MB) {
is_ethernet = 1;
for (i = 0; i < bdl.bfl_len; i++) {
if (bdl.bfl_list[i] != DLT_EN10MB) {
is_ethernet = 0;
break;
}
}
if (is_ethernet) {
/*
* We reserved one more slot at the end of
* the list.
*/
bdl.bfl_list[bdl.bfl_len] = DLT_DOCSIS;
bdl.bfl_len++;
}
}
p->dlt_count = bdl.bfl_len;
p->dlt_list = bdl.bfl_list;
} else {
if (errno != EINVAL) {
(void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
"BIOCGDLTLIST: %s", pcap_strerror(errno));
goto bad;
}
}
#endif
/*
* If this is an Ethernet device, and we don't have a DLT_ list,
* give it a list with DLT_EN10MB and DLT_DOCSIS. (That'd give
* 802.11 interfaces DLT_DOCSIS, which isn't the right thing to
* do, but there's not much we can do about that without finding
* some other way of determining whether it's an Ethernet or 802.11
* device.)
*/
if (p->linktype == DLT_EN10MB && p->dlt_count == 0) {
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;
}
}
#if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT)
/*
* Do a BIOCSHDRCMPLT, if defined, to turn that flag on, so
* the link-layer source address isn't forcibly overwritten.
* (Should we ignore errors? Should we do this only if
* we're open for writing?)
*
* XXX - I seem to remember some packet-sending bug in some
* BSDs - check CVS log for "bpf.c"?
*/
if (ioctl(fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) {
(void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
"BIOCSHDRCMPLT: %s", pcap_strerror(errno));
goto bad;
}
#endif
/* set timeout */
if (to_ms != 0) {
/*
* XXX - is this seconds/nanoseconds in AIX?
* (Treating it as such doesn't fix the timeout
* problem described below.)
*/
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 */
if (ioctl(p->fd, BIOCPROMISC, NULL) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCPROMISC: %s",
pcap_strerror(errno));
}
}
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;
}
#ifdef _AIX
/* For some strange reason this seems to prevent the EFAULT
* problems we have experienced from AIX BPF. */
memset(p->buffer, 0x0, p->bufsize);
#endif
/*
* If there's no filter program installed, there's
* no indication to the kernel of what the snapshot
* length should be, so no snapshotting is done.
*
* Therefore, when we open the device, we install
* an "accept everything" filter with the specified
* snapshot length.
*/
total_insn.code = (u_short)(BPF_RET | BPF_K);
total_insn.jt = 0;
total_insn.jf = 0;
total_insn.k = snaplen;
total_prog.bf_len = 1;
total_prog.bf_insns = &total_insn;
if (ioctl(p->fd, BIOCSETF, (caddr_t)&total_prog) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
pcap_strerror(errno));
goto bad;
}
/*
* On most BPF platforms, either you can do a "select()" or
* "poll()" on a BPF file descriptor and it works correctly,
* or you can do it and it will return "readable" if the
* hold buffer is full but not if the timeout expires *and*
* a non-blocking read will, if the hold buffer is empty
* but the store buffer isn't empty, rotate the buffers
* and return what packets are available.
*
* In the latter case, the fact that a non-blocking read
* will give you the available packets means you can work
* around the failure of "select()" and "poll()" to wake up
* and return "readable" when the timeout expires by using
* the timeout as the "select()" or "poll()" timeout, putting
* the BPF descriptor into non-blocking mode, and read from
* it regardless of whether "select()" reports it as readable
* or not.
*
* However, in FreeBSD 4.3 and 4.4, "select()" and "poll()"
* won't wake up and return "readable" if the timer expires
* and non-blocking reads return EWOULDBLOCK if the hold
* buffer is empty, even if the store buffer is non-empty.
*
* This means the workaround in question won't work.
*
* Therefore, on FreeBSD 4.3 and 4.4, we set "p->selectable_fd"
* to -1, which means "sorry, you can't use 'select()' or 'poll()'
* here". On all other BPF platforms, we set it to the FD for
* the BPF device; in NetBSD, OpenBSD, and Darwin, a non-blocking
* read will, if the hold buffer is empty and the store buffer
* isn't empty, rotate the buffers and return what packets are
* there (and in sufficiently recent versions of OpenBSD
* "select()" and "poll()" should work correctly).
*
* XXX - what about AIX?
*/
p->selectable_fd = p->fd; /* assume select() works until we know otherwise */
if (uname(&osinfo) == 0) {
/*
* We can check what OS this is.
*/
if (strcmp(osinfo.sysname, "FreeBSD") == 0) {
if (strncmp(osinfo.release, "4.3-", 4) == 0 ||
strncmp(osinfo.release, "4.4-", 4) == 0)
p->selectable_fd = -1;
}
}
p->read_op = pcap_read_bpf;
p->inject_op = pcap_inject_bpf;
p->setfilter_op = pcap_setfilter_bpf;
p->setdirection_op = pcap_setdirection_bpf;
p->set_datalink_op = pcap_set_datalink_bpf;
p->getnonblock_op = pcap_getnonblock_fd;
p->setnonblock_op = pcap_setnonblock_fd;
p->stats_op = pcap_stats_bpf;
p->close_op = pcap_close_common;
return (p);
bad:
(void)close(fd);
if (p->dlt_list != NULL)
free(p->dlt_list);
free(p);
return (NULL);
}
int
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
{
#ifdef HAVE_DAG_API
if (dag_platform_finddevs(alldevsp, errbuf) < 0)
return (-1);
#endif /* HAVE_DAG_API */
return (0);
}
static int
pcap_setfilter_bpf(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) {
/*
* XXX - what if we already have a filter in the kernel?
*/
if (install_bpf_program(p, fp) < 0)
return (-1);
p->md.use_bpf = 0; /* filtering in userland */
return (0);
}
/*
* Free any user-mode filter we might happen to have installed.
*/
pcap_freecode(&p->fcode);
/*
* Try to install the kernel filter.
*/
if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
pcap_strerror(errno));
return (-1);
}
p->md.use_bpf = 1; /* filtering in the kernel */
/*
* Discard any previously-received packets, as they might have
* passed whatever filter was formerly in effect, but might
* not pass this filter (BIOCSETF discards packets buffered
* in the kernel, so you can lose packets in any case).
*/
p->cc = 0;
return (0);
}
/*
* Set direction flag: Which packets do we accept on a forwarding
* single device? IN, OUT or both?
*/
static int
pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
{
#ifdef BIOCSSEESENT
u_int seesent;
#endif
/*
* We don't support PCAP_D_OUT.
*/
if (d == PCAP_D_OUT) {
snprintf(p->errbuf, sizeof(p->errbuf),
"Setting direction to PCAP_D_OUT is not supported on BPF");
return -1;
}
#ifdef BIOCSSEESENT
seesent = (d == PCAP_D_INOUT);
if (ioctl(p->fd, BIOCSSEESENT, &seesent) == -1) {
(void) snprintf(p->errbuf, sizeof(p->errbuf),
"Cannot set direction to %s: %s",
(d == PCAP_D_INOUT) ? "PCAP_D_INOUT" : "PCAP_D_IN",
strerror(errno));
return (-1);
}
return (0);
#else
(void) snprintf(p->errbuf, sizeof(p->errbuf),
"This system doesn't support BIOCSSEESENT, so the direction can't be set");
return (-1);
#endif
}
static int
pcap_set_datalink_bpf(pcap_t *p, int dlt)
{
#ifdef BIOCSDLT
if (ioctl(p->fd, BIOCSDLT, &dlt) == -1) {
(void) snprintf(p->errbuf, sizeof(p->errbuf),
"Cannot set DLT %d: %s", dlt, strerror(errno));
return (-1);
}
#endif
return (0);
}