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pcap.c
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/*
* Copyright (c) 1993, 1994, 1995, 1996, 1997, 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 the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the Computer Systems
* Engineering Group at Lawrence Berkeley Laboratory.
* 4. Neither the name of the University nor of the Laboratory may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif
#include <sys/types.h>
#endif /* WIN32 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if !defined(_MSC_VER) && !defined(__BORLANDC__) && !defined(__MINGW32__)
#include <unistd.h>
#endif
#include <fcntl.h>
#include <errno.h>
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#ifdef MSDOS
#include "pcap-dos.h"
#endif
#include "pcap-int.h"
#ifdef HAVE_DAG_API
#include "pcap-dag.h"
#endif /* HAVE_DAG_API */
#ifdef HAVE_SEPTEL_API
#include "pcap-septel.h"
#endif /* HAVE_SEPTEL_API */
#ifdef HAVE_SNF_API
#include "pcap-snf.h"
#endif /* HAVE_SNF_API */
#ifdef PCAP_SUPPORT_USB
#include "pcap-usb-linux.h"
#endif
#ifdef PCAP_SUPPORT_BT
#include "pcap-bt-linux.h"
#endif
#ifdef PCAP_SUPPORT_BT_MONITOR
#include "pcap-bt-monitor-linux.h"
#endif
#ifdef PCAP_SUPPORT_CAN
#include "pcap-can-linux.h"
#endif
#ifdef PCAP_SUPPORT_CANUSB
#include "pcap-canusb-linux.h"
#endif
#ifdef PCAP_SUPPORT_NETFILTER
#include "pcap-netfilter-linux.h"
#endif
#ifdef PCAP_SUPPORT_DBUS
#include "pcap-dbus.h"
#endif
#ifdef PCAP_SUPPORT_NETMAP
pcap_t* pcap_netmap_create(const char *device, char *ebuf, int *is_ours);
#endif
int
pcap_not_initialized(pcap_t *pcap _U_)
{
/* this means 'not initialized' */
return (PCAP_ERROR_NOT_ACTIVATED);
}
#ifdef WIN32
Adapter *
pcap_no_adapter(pcap_t *pcap _U_)
{
return (NULL);
}
#endif
/*
* Returns 1 if rfmon mode can be set on the pcap_t, 0 if it can't,
* a PCAP_ERROR value on an error.
*/
int
pcap_can_set_rfmon(pcap_t *p)
{
return (p->can_set_rfmon_op(p));
}
/*
* For systems where rfmon mode is never supported.
*/
static int
pcap_cant_set_rfmon(pcap_t *p _U_)
{
return (0);
}
/*
* Sets *tstamp_typesp to point to an array 1 or more supported time stamp
* types; the return value is the number of supported time stamp types.
* The list should be freed by a call to pcap_free_tstamp_types() when
* you're done with it.
*
* A return value of 0 means "you don't get a choice of time stamp type",
* in which case *tstamp_typesp is set to null.
*
* PCAP_ERROR is returned on error.
*/
int
pcap_list_tstamp_types(pcap_t *p, int **tstamp_typesp)
{
if (p->tstamp_type_count == 0) {
/*
* We don't support multiple time stamp types.
*/
*tstamp_typesp = NULL;
} else {
*tstamp_typesp = (int*)calloc(sizeof(**tstamp_typesp),
p->tstamp_type_count);
if (*tstamp_typesp == NULL) {
(void)snprintf(p->errbuf, sizeof(p->errbuf),
"malloc: %s", pcap_strerror(errno));
return (PCAP_ERROR);
}
(void)memcpy(*tstamp_typesp, p->tstamp_type_list,
sizeof(**tstamp_typesp) * p->tstamp_type_count);
}
return (p->tstamp_type_count);
}
/*
* In Windows, you might have a library built with one version of the
* C runtime library and an application built with another version of
* the C runtime library, which means that the library might use one
* version of malloc() and free() and the application might use another
* version of malloc() and free(). If so, that means something
* allocated by the library cannot be freed by the application, so we
* need to have a pcap_free_tstamp_types() routine to free up the list
* allocated by pcap_list_tstamp_types(), even though it's just a wrapper
* around free().
*/
void
pcap_free_tstamp_types(int *tstamp_type_list)
{
free(tstamp_type_list);
}
/*
* Default one-shot callback; overridden for capture types where the
* packet data cannot be guaranteed to be available after the callback
* returns, so that a copy must be made.
*/
void
pcap_oneshot(u_char *user, const struct pcap_pkthdr *h, const u_char *pkt)
{
struct oneshot_userdata *sp = (struct oneshot_userdata *)user;
*sp->hdr = *h;
*sp->pkt = pkt;
}
const u_char *
pcap_next(pcap_t *p, struct pcap_pkthdr *h)
{
struct oneshot_userdata s;
const u_char *pkt;
s.hdr = h;
s.pkt = &pkt;
s.pd = p;
if (pcap_dispatch(p, 1, p->oneshot_callback, (u_char *)&s) <= 0)
return (0);
return (pkt);
}
int
pcap_next_ex(pcap_t *p, struct pcap_pkthdr **pkt_header,
const u_char **pkt_data)
{
struct oneshot_userdata s;
s.hdr = &p->pcap_header;
s.pkt = pkt_data;
s.pd = p;
/* Saves a pointer to the packet headers */
*pkt_header= &p->pcap_header;
if (p->rfile != NULL) {
int status;
/* We are on an offline capture */
status = pcap_offline_read(p, 1, p->oneshot_callback,
(u_char *)&s);
/*
* Return codes for pcap_offline_read() are:
* - 0: EOF
* - -1: error
* - >1: OK
* The first one ('0') conflicts with the return code of
* 0 from pcap_read() meaning "no packets arrived before
* the timeout expired", so we map it to -2 so you can
* distinguish between an EOF from a savefile and a
* "no packets arrived before the timeout expired, try
* again" from a live capture.
*/
if (status == 0)
return (-2);
else
return (status);
}
/*
* Return codes for pcap_read() are:
* - 0: timeout
* - -1: error
* - -2: loop was broken out of with pcap_breakloop()
* - >1: OK
* The first one ('0') conflicts with the return code of 0 from
* pcap_offline_read() meaning "end of file".
*/
return (p->read_op(p, 1, p->oneshot_callback, (u_char *)&s));
}
#if defined(DAG_ONLY)
int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
return (dag_findalldevs(alldevsp, errbuf));
}
pcap_t *
pcap_create(const char *source, char *errbuf)
{
int is_ours;
return (dag_create(source, errbuf, &is_ours));
}
#elif defined(SEPTEL_ONLY)
int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
return (septel_findalldevs(alldevsp, errbuf));
}
pcap_t *
pcap_create(const char *source, char *errbuf)
{
int is_ours;
return (septel_create(source, errbuf, &is_ours));
}
#elif defined(SNF_ONLY)
int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
return (snf_findalldevs(alldevsp, errbuf));
}
pcap_t *
pcap_create(const char *source, char *errbuf)
{
int is_ours;
return (snf_create(source, errbuf, &is_ours));
}
#else /* regular pcap */
struct capture_source_type {
int (*findalldevs_op)(pcap_if_t **, char *);
pcap_t *(*create_op)(const char *, char *, int *);
} capture_source_types[] = {
#ifdef PCAP_SUPPORT_NETMAP
{ NULL, pcap_netmap_create },
#endif
#ifdef HAVE_DAG_API
{ dag_findalldevs, dag_create },
#endif
#ifdef HAVE_SEPTEL_API
{ septel_findalldevs, septel_create },
#endif
#ifdef HAVE_SNF_API
{ snf_findalldevs, snf_create },
#endif
#ifdef PCAP_SUPPORT_BT
{ bt_findalldevs, bt_create },
#endif
#ifdef PCAP_SUPPORT_BT_MONITOR
{ bt_monitor_findalldevs, bt_monitor_create },
#endif
#if PCAP_SUPPORT_CANUSB
{ canusb_findalldevs, canusb_create },
#endif
#ifdef PCAP_SUPPORT_CAN
{ can_findalldevs, can_create },
#endif
#ifdef PCAP_SUPPORT_USB
{ usb_findalldevs, usb_create },
#endif
#ifdef PCAP_SUPPORT_NETFILTER
{ netfilter_findalldevs, netfilter_create },
#endif
#ifdef PCAP_SUPPORT_DBUS
{ dbus_findalldevs, dbus_create },
#endif
{ NULL, NULL }
};
/*
* Get a list of all capture sources that are up and that we can open.
* Returns -1 on error, 0 otherwise.
* The list, as returned through "alldevsp", may be null if no interfaces
* were up and could be opened.
*/
int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
size_t i;
/*
* Get the list of regular interfaces first.
*/
if (pcap_findalldevs_interfaces(alldevsp, errbuf) == -1)
return (-1); /* failure */
/*
* Add any interfaces that need a platform-specific mechanism
* to find.
*/
if (pcap_platform_finddevs(alldevsp, errbuf) == -1) {
/*
* We had an error; free the list we've been
* constructing.
*/
if (*alldevsp != NULL) {
pcap_freealldevs(*alldevsp);
*alldevsp = NULL;
}
return (-1);
}
/*
* Ask each of the non-local-network-interface capture
* source types what interfaces they have.
*/
for (i = 0; capture_source_types[i].findalldevs_op != NULL; i++) {
if (capture_source_types[i].findalldevs_op(alldevsp, errbuf) == -1) {
/*
* We had an error; free the list we've been
* constructing.
*/
if (*alldevsp != NULL) {
pcap_freealldevs(*alldevsp);
*alldevsp = NULL;
}
return (-1);
}
}
return (0);
}
pcap_t *
pcap_create(const char *source, char *errbuf)
{
size_t i;
int is_theirs;
pcap_t *p;
/*
* A null source name is equivalent to the "any" device -
* which might not be supported on this platform, but
* this means that you'll get a "not supported" error
* rather than, say, a crash when we try to dereference
* the null pointer.
*/
if (source == NULL)
source = "any";
/*
* Try each of the non-local-network-interface capture
* source types until we find one that works for this
* device or run out of types.
*/
for (i = 0; capture_source_types[i].create_op != NULL; i++) {
is_theirs = 0;
p = capture_source_types[i].create_op(source, errbuf, &is_theirs);
if (is_theirs) {
/*
* The device name refers to a device of the
* type in question; either it succeeded,
* in which case p refers to a pcap_t to
* later activate for the device, or it
* failed, in which case p is null and we
* should return that to report the failure
* to create.
*/
return (p);
}
}
/*
* OK, try it as a regular network interface.
*/
return (pcap_create_interface(source, errbuf));
}
#endif
static void
initialize_ops(pcap_t *p)
{
/*
* Set operation pointers for operations that only work on
* an activated pcap_t to point to a routine that returns
* a "this isn't activated" error.
*/
p->read_op = (read_op_t)pcap_not_initialized;
p->inject_op = (inject_op_t)pcap_not_initialized;
p->setfilter_op = (setfilter_op_t)pcap_not_initialized;
p->setdirection_op = (setdirection_op_t)pcap_not_initialized;
p->set_datalink_op = (set_datalink_op_t)pcap_not_initialized;
p->getnonblock_op = (getnonblock_op_t)pcap_not_initialized;
p->setnonblock_op = (setnonblock_op_t)pcap_not_initialized;
p->stats_op = (stats_op_t)pcap_not_initialized;
#ifdef WIN32
p->setbuff_op = (setbuff_op_t)pcap_not_initialized;
p->setmode_op = (setmode_op_t)pcap_not_initialized;
p->setmintocopy_op = (setmintocopy_op_t)pcap_not_initialized;
p->getadapter_op = pcap_no_adapter;
#endif
/*
* Default cleanup operation - implementations can override
* this, but should call pcap_cleanup_live_common() after
* doing their own additional cleanup.
*/
p->cleanup_op = pcap_cleanup_live_common;
/*
* In most cases, the standard one-shot callback can
* be used for pcap_next()/pcap_next_ex().
*/
p->oneshot_callback = pcap_oneshot;
}
static pcap_t *
pcap_alloc_pcap_t(char *ebuf, size_t size)
{
char *chunk;
pcap_t *p;
/*
* Allocate a chunk of memory big enough for a pcap_t
* plus a structure following it of size "size". The
* structure following it is a private data structure
* for the routines that handle this pcap_t.
*/
chunk = malloc(sizeof (pcap_t) + size);
if (chunk == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
return (NULL);
}
memset(chunk, 0, sizeof (pcap_t) + size);
/*
* Get a pointer to the pcap_t at the beginning.
*/
p = (pcap_t *)chunk;
#ifndef WIN32
p->fd = -1; /* not opened yet */
p->selectable_fd = -1;
#endif
if (size == 0) {
/* No private data was requested. */
p->priv = NULL;
} else {
/*
* Set the pointer to the private data; that's the structure
* of size "size" following the pcap_t.
*/
p->priv = (void *)(chunk + sizeof (pcap_t));
}
return (p);
}
pcap_t *
pcap_create_common(const char *source, char *ebuf, size_t size)
{
pcap_t *p;
p = pcap_alloc_pcap_t(ebuf, size);
if (p == NULL)
return (NULL);
p->opt.source = strdup(source);
if (p->opt.source == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
free(p);
return (NULL);
}
/*
* Default to "can't set rfmon mode"; if it's supported by
* a platform, the create routine that called us can set
* the op to its routine to check whether a particular
* device supports it.
*/
p->can_set_rfmon_op = pcap_cant_set_rfmon;
initialize_ops(p);
/* put in some defaults*/
pcap_set_snaplen(p, MAXIMUM_SNAPLEN); /* max packet size */
p->opt.timeout = 0; /* no timeout specified */
p->opt.buffer_size = 0; /* use the platform's default */
p->opt.promisc = 0;
p->opt.rfmon = 0;
p->opt.immediate = 0;
p->opt.tstamp_type = -1; /* default to not setting time stamp type */
p->opt.tstamp_precision = PCAP_TSTAMP_PRECISION_MICRO;
/*
* Start out with no BPF code generation flags set.
*/
p->bpf_codegen_flags = 0;
return (p);
}
int
pcap_check_activated(pcap_t *p)
{
if (p->activated) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "can't perform "
" operation on activated capture");
return (-1);
}
return (0);
}
int
pcap_set_snaplen(pcap_t *p, int snaplen)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->snapshot = snaplen;
return (0);
}
int
pcap_set_promisc(pcap_t *p, int promisc)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.promisc = promisc;
return (0);
}
int
pcap_set_rfmon(pcap_t *p, int rfmon)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.rfmon = rfmon;
return (0);
}
int
pcap_set_timeout(pcap_t *p, int timeout_ms)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.timeout = timeout_ms;
return (0);
}
int
pcap_set_tstamp_type(pcap_t *p, int tstamp_type)
{
int i;
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
/*
* If p->tstamp_type_count is 0, we only support PCAP_TSTAMP_HOST;
* the default time stamp type is PCAP_TSTAMP_HOST.
*/
if (p->tstamp_type_count == 0) {
if (tstamp_type == PCAP_TSTAMP_HOST) {
p->opt.tstamp_type = tstamp_type;
return (0);
}
} else {
/*
* Check whether we claim to support this type of time stamp.
*/
for (i = 0; i < p->tstamp_type_count; i++) {
if (p->tstamp_type_list[i] == tstamp_type) {
/*
* Yes.
*/
p->opt.tstamp_type = tstamp_type;
return (0);
}
}
}
/*
* We don't support this type of time stamp.
*/
return (PCAP_WARNING_TSTAMP_TYPE_NOTSUP);
}
int
pcap_set_immediate_mode(pcap_t *p, int immediate)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.immediate = immediate;
return (0);
}
int
pcap_set_buffer_size(pcap_t *p, int buffer_size)
{
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.buffer_size = buffer_size;
return (0);
}
int
pcap_set_tstamp_precision(pcap_t *p, int tstamp_precision)
{
int i;
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
/*
* If p->tstamp_precision_count is 0, we only support setting
* the time stamp precision to microsecond precision; every
* pcap module *MUST* support microsecond precision, even if
* it does so by converting the native precision to
* microseconds.
*/
if (p->tstamp_precision_count == 0) {
if (tstamp_precision == PCAP_TSTAMP_PRECISION_MICRO) {
p->opt.tstamp_precision = tstamp_precision;
return (0);
}
} else {
/*
* Check whether we claim to support this precision of
* time stamp.
*/
for (i = 0; i < p->tstamp_precision_count; i++) {
if (p->tstamp_precision_list[i] == tstamp_precision) {
/*
* Yes.
*/
p->opt.tstamp_precision = tstamp_precision;
return (0);
}
}
}
/*
* We don't support this time stamp precision.
*/
return (PCAP_ERROR_TSTAMP_PRECISION_NOTSUP);
}
int
pcap_get_tstamp_precision(pcap_t *p)
{
return (p->opt.tstamp_precision);
}
int
pcap_activate(pcap_t *p)
{
int status;
/*
* Catch attempts to re-activate an already-activated
* pcap_t; this should, for example, catch code that
* calls pcap_open_live() followed by pcap_activate(),
* as some code that showed up in a Stack Exchange
* question did.
*/
if (pcap_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
status = p->activate_op(p);
if (status >= 0)
p->activated = 1;
else {
if (p->errbuf[0] == '\0') {
/*
* No error message supplied by the activate routine;
* for the benefit of programs that don't specially
* handle errors other than PCAP_ERROR, return the
* error message corresponding to the status.
*/
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s",
pcap_statustostr(status));
}
/*
* Undo any operation pointer setting, etc. done by
* the activate operation.
*/
initialize_ops(p);
}
return (status);
}
pcap_t *
pcap_open_live(const char *source, int snaplen, int promisc, int to_ms, char *errbuf)
{
pcap_t *p;
int status;
p = pcap_create(source, errbuf);
if (p == NULL)
return (NULL);
status = pcap_set_snaplen(p, snaplen);
if (status < 0)
goto fail;
status = pcap_set_promisc(p, promisc);
if (status < 0)
goto fail;
status = pcap_set_timeout(p, to_ms);
if (status < 0)
goto fail;
/*
* Mark this as opened with pcap_open_live(), so that, for
* example, we show the full list of DLT_ values, rather
* than just the ones that are compatible with capturing
* when not in monitor mode. That allows existing applications
* to work the way they used to work, but allows new applications
* that know about the new open API to, for example, find out the
* DLT_ values that they can select without changing whether
* the adapter is in monitor mode or not.
*/
p->oldstyle = 1;
status = pcap_activate(p);
if (status < 0)
goto fail;
return (p);
fail:
if (status == PCAP_ERROR)
snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", source,
p->errbuf);
else if (status == PCAP_ERROR_NO_SUCH_DEVICE ||
status == PCAP_ERROR_PERM_DENIED ||
status == PCAP_ERROR_PROMISC_PERM_DENIED)
snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s (%s)", source,
pcap_statustostr(status), p->errbuf);
else
snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", source,
pcap_statustostr(status));
pcap_close(p);
return (NULL);
}
pcap_t *
pcap_open_offline_common(char *ebuf, size_t size)
{
pcap_t *p;
p = pcap_alloc_pcap_t(ebuf, size);
if (p == NULL)
return (NULL);
p->opt.tstamp_precision = PCAP_TSTAMP_PRECISION_MICRO;
p->opt.source = strdup("(savefile)");
if (p->opt.source == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
free(p);
return (NULL);
}
return (p);
}
int
pcap_dispatch(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
return (p->read_op(p, cnt, callback, user));
}
/*
* XXX - is this necessary?
*/
int
pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
return (p->read_op(p, cnt, callback, user));
}
int
pcap_loop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
register int n;
for (;;) {
if (p->rfile != NULL) {
/*
* 0 means EOF, so don't loop if we get 0.
*/
n = pcap_offline_read(p, cnt, callback, user);
} else {
/*
* XXX keep reading until we get something
* (or an error occurs)
*/
do {
n = p->read_op(p, cnt, callback, user);
} while (n == 0);
}
if (n <= 0)
return (n);
if (!PACKET_COUNT_IS_UNLIMITED(cnt)) {
cnt -= n;
if (cnt <= 0)
return (0);
}
}
}
/*
* Force the loop in "pcap_read()" or "pcap_read_offline()" to terminate.
*/
void
pcap_breakloop(pcap_t *p)
{
p->break_loop = 1;
}
int
pcap_datalink(pcap_t *p)
{
if (!p->activated)
return (PCAP_ERROR_NOT_ACTIVATED);
return (p->linktype);
}
int
pcap_datalink_ext(pcap_t *p)
{
if (!p->activated)
return (PCAP_ERROR_NOT_ACTIVATED);
return (p->linktype_ext);
}
int
pcap_list_datalinks(pcap_t *p, int **dlt_buffer)
{
if (!p->activated)
return (PCAP_ERROR_NOT_ACTIVATED);
if (p->dlt_count == 0) {
/*
* We couldn't fetch the list of DLTs, which means
* this platform doesn't support changing the
* DLT for an interface. Return a list of DLTs
* containing only the DLT this device supports.
*/
*dlt_buffer = (int*)malloc(sizeof(**dlt_buffer));
if (*dlt_buffer == NULL) {
(void)snprintf(p->errbuf, sizeof(p->errbuf),
"malloc: %s", pcap_strerror(errno));
return (PCAP_ERROR);
}
**dlt_buffer = p->linktype;
return (1);
} else {
*dlt_buffer = (int*)calloc(sizeof(**dlt_buffer), p->dlt_count);
if (*dlt_buffer == NULL) {
(void)snprintf(p->errbuf, sizeof(p->errbuf),
"malloc: %s", pcap_strerror(errno));
return (PCAP_ERROR);
}
(void)memcpy(*dlt_buffer, p->dlt_list,
sizeof(**dlt_buffer) * p->dlt_count);
return (p->dlt_count);
}
}
/*
* In Windows, you might have a library built with one version of the
* C runtime library and an application built with another version of
* the C runtime library, which means that the library might use one
* version of malloc() and free() and the application might use another
* version of malloc() and free(). If so, that means something
* allocated by the library cannot be freed by the application, so we
* need to have a pcap_free_datalinks() routine to free up the list
* allocated by pcap_list_datalinks(), even though it's just a wrapper
* around free().
*/
void
pcap_free_datalinks(int *dlt_list)
{
free(dlt_list);
}
int
pcap_set_datalink(pcap_t *p, int dlt)
{
int i;
const char *dlt_name;
if (p->dlt_count == 0 || p->set_datalink_op == NULL) {
/*
* We couldn't fetch the list of DLTs, or we don't
* have a "set datalink" operation, which means
* this platform doesn't support changing the
* DLT for an interface. Check whether the new
* DLT is the one this interface supports.
*/
if (p->linktype != dlt)
goto unsupported;
/*
* It is, so there's nothing we need to do here.
*/
return (0);
}
for (i = 0; i < p->dlt_count; i++)
if (p->dlt_list[i] == dlt)
break;
if (i >= p->dlt_count)
goto unsupported;
if (p->dlt_count == 2 && p->dlt_list[0] == DLT_EN10MB &&
dlt == DLT_DOCSIS) {
/*
* This is presumably an Ethernet device, as the first
* link-layer type it offers is DLT_EN10MB, and the only
* other type it offers is DLT_DOCSIS. That means that
* we can't tell the driver to supply DOCSIS link-layer
* headers - we're just pretending that's what we're
* getting, as, presumably, we're capturing on a dedicated
* link to a Cisco Cable Modem Termination System, and
* it's putting raw DOCSIS frames on the wire inside low-level