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<
/*
* pcap-linux.c: Packet capture interface to the Linux kernel
*
* Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
* Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
*
* License: BSD
*
* 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. The names of the authors may not 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.
*
* Modifications: Added PACKET_MMAP support
* Paolo Abeni <paolo.abeni@email.it>
* Added TPACKET_V3 support
* Gabor Tatarka <gabor.tatarka@ericsson.com>
*
* based on previous works of:
* Simon Patarin <patarin@cs.unibo.it>
* Phil Wood <cpw@lanl.gov>
*
* Monitor-mode support for mac80211 includes code taken from the iw
* command; the copyright notice for that code is
*
* Copyright (c) 2007, 2008 Johannes Berg
* Copyright (c) 2007 Andy Lutomirski
* Copyright (c) 2007 Mike Kershaw
* Copyright (c) 2008 Gábor Stefanik
*
* 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/*
* Known problems with 2.0[.x] kernels:
*
* - The loopback device gives every packet twice; on 2.2[.x] kernels,
* if we use PF_PACKET, we can filter out the transmitted version
* of the packet by using data in the "sockaddr_ll" returned by
* "recvfrom()", but, on 2.0[.x] kernels, we have to use
* PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
* "sockaddr_pkt" which doesn't give us enough information to let
* us do that.
*
* - We have to set the interface's IFF_PROMISC flag ourselves, if
* we're to run in promiscuous mode, which means we have to turn
* it off ourselves when we're done; the kernel doesn't keep track
* of how many sockets are listening promiscuously, which means
* it won't get turned off automatically when no sockets are
* listening promiscuously. We catch "pcap_close()" and, for
* interfaces we put into promiscuous mode, take them out of
* promiscuous mode - which isn't necessarily the right thing to
* do, if another socket also requested promiscuous mode between
* the time when we opened the socket and the time when we close
* the socket.
*
* - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
* return the amount of data that you could have read, rather than
* the amount that was returned, so we can't just allocate a buffer
* whose size is the snapshot length and pass the snapshot length
* as the byte count, and also pass MSG_TRUNC, so that the return
* value tells us how long the packet was on the wire.
*
* This means that, if we want to get the actual size of the packet,
* so we can return it in the "len" field of the packet header,
* we have to read the entire packet, not just the part that fits
* within the snapshot length, and thus waste CPU time copying data
* from the kernel that our caller won't see.
*
* We have to get the actual size, and supply it in "len", because
* otherwise, the IP dissector in tcpdump, for example, will complain
* about "truncated-ip", as the packet will appear to have been
* shorter, on the wire, than the IP header said it should have been.
*/
#define _GNU_SOURCE
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <sys/mman.h>
#include <linux/if.h>
#include <linux/if_packet.h>
#include <linux/sockios.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <net/if_arp.h>
#include <poll.h>
#include <dirent.h>
#include "pcap-int.h"
#include "pcap/sll.h"
#include "pcap/vlan.h"
/*
* If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
* sockets rather than SOCK_PACKET sockets.
*
* To use them, we include <linux/if_packet.h> rather than
* <netpacket/packet.h>; we do so because
*
* some Linux distributions (e.g., Slackware 4.0) have 2.2 or
* later kernels and libc5, and don't provide a <netpacket/packet.h>
* file;
*
* not all versions of glibc2 have a <netpacket/packet.h> file
* that defines stuff needed for some of the 2.4-or-later-kernel
* features, so if the system has a 2.4 or later kernel, we
* still can't use those features.
*
* We're already including a number of other <linux/XXX.h> headers, and
* this code is Linux-specific (no other OS has PF_PACKET sockets as
* a raw packet capture mechanism), so it's not as if you gain any
* useful portability by using <netpacket/packet.h>
*
* XXX - should we just include <linux/if_packet.h> even if PF_PACKET
* isn't defined? It only defines one data structure in 2.0.x, so
* it shouldn't cause any problems.
*/
#ifdef PF_PACKET
# include <linux/if_packet.h>
/*
* On at least some Linux distributions (for example, Red Hat 5.2),
* there's no <netpacket/packet.h> file, but PF_PACKET is defined if
* you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
* any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
* the PACKET_xxx stuff.
*
* So we check whether PACKET_HOST is defined, and assume that we have
* PF_PACKET sockets only if it is defined.
*/
# ifdef PACKET_HOST
# define HAVE_PF_PACKET_SOCKETS
# ifdef PACKET_AUXDATA
# define HAVE_PACKET_AUXDATA
# endif /* PACKET_AUXDATA */
# endif /* PACKET_HOST */
/* check for memory mapped access avaibility. We assume every needed
* struct is defined if the macro TPACKET_HDRLEN is defined, because it
* uses many ring related structs and macros */
# ifdef TPACKET_HDRLEN
# define HAVE_PACKET_RING
# ifdef TPACKET3_HDRLEN
# define HAVE_TPACKET3
# endif /* TPACKET3_HDRLEN */
# ifdef TPACKET2_HDRLEN
# define HAVE_TPACKET2
# else /* TPACKET2_HDRLEN */
# define TPACKET_V1 0 /* Old kernel with only V1, so no TPACKET_Vn defined */
# endif /* TPACKET2_HDRLEN */
# endif /* TPACKET_HDRLEN */
#endif /* PF_PACKET */
#ifdef SO_ATTACH_FILTER
#include <linux/types.h>
#include <linux/filter.h>
#endif
#ifdef HAVE_LINUX_NET_TSTAMP_H
#include <linux/net_tstamp.h>
#endif
/*
* Got Wireless Extensions?
*/
#ifdef HAVE_LINUX_WIRELESS_H
#include <linux/wireless.h>
#endif /* HAVE_LINUX_WIRELESS_H */
/*
* Got libnl?
*/
#ifdef HAVE_LIBNL
#include <linux/nl80211.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#endif /* HAVE_LIBNL */
/*
* Got ethtool support?
*/
#ifdef HAVE_LINUX_ETHTOOL_H
#include <linux/ethtool.h>
#endif
#ifndef HAVE_SOCKLEN_T
typedef int socklen_t;
#endif
#ifndef MSG_TRUNC
/*
* This is being compiled on a system that lacks MSG_TRUNC; define it
* with the value it has in the 2.2 and later kernels, so that, on
* those kernels, when we pass it in the flags argument to "recvfrom()"
* we're passing the right value and thus get the MSG_TRUNC behavior
* we want. (We don't get that behavior on 2.0[.x] kernels, because
* they didn't support MSG_TRUNC.)
*/
#define MSG_TRUNC 0x20
#endif
#ifndef SOL_PACKET
/*
* This is being compiled on a system that lacks SOL_PACKET; define it
* with the value it has in the 2.2 and later kernels, so that we can
* set promiscuous mode in the good modern way rather than the old
* 2.0-kernel crappy way.
*/
#define SOL_PACKET 263
#endif
#define MAX_LINKHEADER_SIZE 256
/*
* When capturing on all interfaces we use this as the buffer size.
* Should be bigger then all MTUs that occur in real life.
* 64kB should be enough for now.
*/
#define BIGGER_THAN_ALL_MTUS (64*1024)
/*
* Private data for capturing on Linux SOCK_PACKET or PF_PACKET sockets.
*/
struct pcap_linux {
u_int packets_read; /* count of packets read with recvfrom() */
long proc_dropped; /* packets reported dropped by /proc/net/dev */
struct pcap_stat stat;
char *device; /* device name */
int filter_in_userland; /* must filter in userland */
int blocks_to_filter_in_userland;
int must_do_on_close; /* stuff we must do when we close */
int timeout; /* timeout for buffering */
int sock_packet; /* using Linux 2.0 compatible interface */
int cooked; /* using SOCK_DGRAM rather than SOCK_RAW */
int ifindex; /* interface index of device we're bound to */
int lo_ifindex; /* interface index of the loopback device */
bpf_u_int32 oldmode; /* mode to restore when turning monitor mode off */
char *mondevice; /* mac80211 monitor device we created */
u_char *mmapbuf; /* memory-mapped region pointer */
size_t mmapbuflen; /* size of region */
int vlan_offset; /* offset at which to insert vlan tags; if -1, don't insert */
u_int tp_version; /* version of tpacket_hdr for mmaped ring */
u_int tp_hdrlen; /* hdrlen of tpacket_hdr for mmaped ring */
u_char *oneshot_buffer; /* buffer for copy of packet */
#ifdef HAVE_TPACKET3
unsigned char *current_packet; /* Current packet within the TPACKET_V3 block. Move to next block if NULL. */
int packets_left; /* Unhandled packets left within the block from previous call to pcap_read_linux_mmap_v3 in case of TPACKET_V3. */
#endif
};
/*
* Stuff to do when we close.
*/
#define MUST_CLEAR_PROMISC 0x00000001 /* clear promiscuous mode */
#define MUST_CLEAR_RFMON 0x00000002 /* clear rfmon (monitor) mode */
#define MUST_DELETE_MONIF 0x00000004 /* delete monitor-mode interface */
/*
* Prototypes for internal functions and methods.
*/
static void map_arphrd_to_dlt(pcap_t *, int, const char *, int);
#ifdef HAVE_PF_PACKET_SOCKETS
static short int map_packet_type_to_sll_type(short int);
#endif
static int pcap_activate_linux(pcap_t *);
static int activate_old(pcap_t *);
static int activate_new(pcap_t *);
static int activate_mmap(pcap_t *, int *);
static int pcap_can_set_rfmon_linux(pcap_t *);
static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
static int pcap_inject_linux(pcap_t *, const void *, size_t);
static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
static int pcap_set_datalink_linux(pcap_t *, int);
static void pcap_cleanup_linux(pcap_t *);
union thdr {
struct tpacket_hdr *h1;
#ifdef HAVE_TPACKET2
struct tpacket2_hdr *h2;
#endif
#ifdef HAVE_TPACKET3
struct tpacket_block_desc *h3;
#endif
void *raw;
};
#ifdef HAVE_PACKET_RING
#define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset])
static void destroy_ring(pcap_t *handle);
static int create_ring(pcap_t *handle, int *status);
static int prepare_tpacket_socket(pcap_t *handle);
static void pcap_cleanup_linux_mmap(pcap_t *);
static int pcap_read_linux_mmap_v1(pcap_t *, int, pcap_handler , u_char *);
#ifdef HAVE_TPACKET2
static int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *);
#endif
#ifdef HAVE_TPACKET3
static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *);
#endif
static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *);
static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf);
static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf);
static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
const u_char *bytes);
#endif
/*
* Wrap some ioctl calls
*/
#ifdef HAVE_PF_PACKET_SOCKETS
static int iface_get_id(int fd, const char *device, char *ebuf);
#endif /* HAVE_PF_PACKET_SOCKETS */
static int iface_get_mtu(int fd, const char *device, char *ebuf);
static int iface_get_arptype(int fd, const char *device, char *ebuf);
#ifdef HAVE_PF_PACKET_SOCKETS
static int iface_bind(int fd, int ifindex, char *ebuf);
#ifdef IW_MODE_MONITOR
static int has_wext(int sock_fd, const char *device, char *ebuf);
#endif /* IW_MODE_MONITOR */
static int enter_rfmon_mode(pcap_t *handle, int sock_fd,
const char *device);
#endif /* HAVE_PF_PACKET_SOCKETS */
static int iface_get_offload(pcap_t *handle);
static int iface_bind_old(int fd, const char *device, char *ebuf);
#ifdef SO_ATTACH_FILTER
static int fix_program(pcap_t *handle, struct sock_fprog *fcode,
int is_mapped);
static int fix_offset(struct bpf_insn *p);
static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
static int reset_kernel_filter(pcap_t *handle);
static struct sock_filter total_insn
= BPF_STMT(BPF_RET | BPF_K, 0);
static struct sock_fprog total_fcode
= { 1, &total_insn };
#endif /* SO_ATTACH_FILTER */
pcap_t *
pcap_create_interface(const char *device, char *ebuf)
{
pcap_t *handle;
handle = pcap_create_common(device, ebuf, sizeof (struct pcap_linux));
if (handle == NULL)
return NULL;
handle->activate_op = pcap_activate_linux;
handle->can_set_rfmon_op = pcap_can_set_rfmon_linux;
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
/*
* We claim that we support:
*
* software time stamps, with no details about their precision;
* hardware time stamps, synced to the host time;
* hardware time stamps, not synced to the host time.
*
* XXX - we can't ask a device whether it supports
* hardware time stamps, so we just claim all devices do.
*/
handle->tstamp_type_count = 3;
handle->tstamp_type_list = malloc(3 * sizeof(u_int));
if (handle->tstamp_type_list == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
free(handle);
return NULL;
}
handle->tstamp_type_list[0] = PCAP_TSTAMP_HOST;
handle->tstamp_type_list[1] = PCAP_TSTAMP_ADAPTER;
handle->tstamp_type_list[2] = PCAP_TSTAMP_ADAPTER_UNSYNCED;
#endif
#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS)
/*
* We claim that we support microsecond and nanosecond time
* stamps.
*
* XXX - with adapter-supplied time stamps, can we choose
* microsecond or nanosecond time stamps on arbitrary
* adapters?
*/
handle->tstamp_precision_count = 2;
handle->tstamp_precision_list = malloc(2 * sizeof(u_int));
if (handle->tstamp_precision_list == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
pcap_strerror(errno));
if (handle->tstamp_type_list != NULL)
free(handle->tstamp_type_list);
free(handle);
return NULL;
}
handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO;
handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO;
#endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */
return handle;
}
#ifdef HAVE_LIBNL
/*
* If interface {if} is a mac80211 driver, the file
* /sys/class/net/{if}/phy80211 is a symlink to
* /sys/class/ieee80211/{phydev}, for some {phydev}.
*
* On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
* least, has a "wmaster0" device and a "wlan0" device; the
* latter is the one with the IP address. Both show up in
* "tcpdump -D" output. Capturing on the wmaster0 device
* captures with 802.11 headers.
*
* airmon-ng searches through /sys/class/net for devices named
* monN, starting with mon0; as soon as one *doesn't* exist,
* it chooses that as the monitor device name. If the "iw"
* command exists, it does "iw dev {if} interface add {monif}
* type monitor", where {monif} is the monitor device. It
* then (sigh) sleeps .1 second, and then configures the
* device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
* is a file, it writes {mondev}, without a newline, to that file,
* and again (sigh) sleeps .1 second, and then iwconfig's that
* device into monitor mode and configures it up. Otherwise,
* you can't do monitor mode.
*
* All these devices are "glued" together by having the
* /sys/class/net/{device}/phy80211 links pointing to the same
* place, so, given a wmaster, wlan, or mon device, you can
* find the other devices by looking for devices with
* the same phy80211 link.
*
* To turn monitor mode off, delete the monitor interface,
* either with "iw dev {monif} interface del" or by sending
* {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
*
* Note: if you try to create a monitor device named "monN", and
* there's already a "monN" device, it fails, as least with
* the netlink interface (which is what iw uses), with a return
* value of -ENFILE. (Return values are negative errnos.) We
* could probably use that to find an unused device.
*
* Yes, you can have multiple monitor devices for a given
* physical device.
*/
/*
* Is this a mac80211 device? If so, fill in the physical device path and
* return 1; if not, return 0. On an error, fill in handle->errbuf and
* return PCAP_ERROR.
*/
static int
get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path,
size_t phydev_max_pathlen)
{
char *pathstr;
ssize_t bytes_read;
/*
* Generate the path string for the symlink to the physical device.
*/
if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't generate path name string for /sys/class/net device",
device);
return PCAP_ERROR;
}
bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen);
if (bytes_read == -1) {
if (errno == ENOENT || errno == EINVAL) {
/*
* Doesn't exist, or not a symlink; assume that
* means it's not a mac80211 device.
*/
free(pathstr);
return 0;
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't readlink %s: %s", device, pathstr,
strerror(errno));
free(pathstr);
return PCAP_ERROR;
}
free(pathstr);
phydev_path[bytes_read] = '\0';
return 1;
}
#ifdef HAVE_LIBNL_SOCKETS
#define get_nl_errmsg nl_geterror
#else
/* libnl 2.x compatibility code */
#define nl_sock nl_handle
static inline struct nl_handle *
nl_socket_alloc(void)
{
return nl_handle_alloc();
}
static inline void
nl_socket_free(struct nl_handle *h)
{
nl_handle_destroy(h);
}
#define get_nl_errmsg strerror
static inline int
__genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache)
{
struct nl_cache *tmp = genl_ctrl_alloc_cache(h);
if (!tmp)
return -ENOMEM;
*cache = tmp;
return 0;
}
#define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache
#endif /* !HAVE_LIBNL_SOCKETS */
struct nl80211_state {
struct nl_sock *nl_sock;
struct nl_cache *nl_cache;
struct genl_family *nl80211;
};
static int
nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device)
{
int err;
state->nl_sock = nl_socket_alloc();
if (!state->nl_sock) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink handle", device);
return PCAP_ERROR;
}
if (genl_connect(state->nl_sock)) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to connect to generic netlink", device);
goto out_handle_destroy;
}
err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate generic netlink cache: %s",
device, get_nl_errmsg(-err));
goto out_handle_destroy;
}
state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
if (!state->nl80211) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl80211 not found", device);
goto out_cache_free;
}
return 0;
out_cache_free:
nl_cache_free(state->nl_cache);
out_handle_destroy:
nl_socket_free(state->nl_sock);
return PCAP_ERROR;
}
static void
nl80211_cleanup(struct nl80211_state *state)
{
genl_family_put(state->nl80211);
nl_cache_free(state->nl_cache);
nl_socket_free(state->nl_sock);
}
static int
add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, device, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_NEW_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
#if defined HAVE_LIBNL_NLE
if (err == -NLE_FAILURE) {
#else
if (err == -ENFILE) {
#endif
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
#if defined HAVE_LIBNL_NLE
if (err == -NLE_FAILURE) {
#else
if (err == -ENFILE) {
#endif
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
/*
* Success.
*/
nlmsg_free(msg);
return 1;
nla_put_failure:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed adding %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
static int
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_DEL_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed deleting %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, get_nl_errmsg(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
/*
* Success.
*/
nlmsg_free(msg);
return 1;
nla_put_failure:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed deleting %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
static int
enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device)
{
struct pcap_linux *handlep = handle->priv;
int ret;
char phydev_path[PATH_MAX+1];
struct nl80211_state nlstate;
struct ifreq ifr;
u_int n;
/*
* Is this a mac80211 device?
*/
ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX);
if (ret < 0)
return ret; /* error */
if (ret == 0)
return 0; /* no error, but not mac80211 device */
/*
* XXX - is this already a monN device?
* If so, we're done.
* Is that determined by old Wireless Extensions ioctls?
*/
/*
* OK, it's apparently a mac80211 device.
* Try to find an unused monN device for it.
*/
ret = nl80211_init(handle, &nlstate, device);
if (ret != 0)
return ret;
for (n = 0; n < UINT_MAX; n++) {
/*
* Try mon{n}.
*/
char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */
snprintf(mondevice, sizeof mondevice, "mon%u", n);
ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice);
if (ret == 1) {
handlep->mondevice = strdup(mondevice);
goto added;
}
if (ret < 0) {
/*
* Hard failure. Just return ret; handle->errbuf
* has already been set.
*/
nl80211_cleanup(&nlstate);
return ret;
}
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: No free monN interfaces", device);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
added:
#if 0
/*
* Sleep for .1 seconds.
*/
delay.tv_sec = 0;
delay.tv_nsec = 500000000;
nanosleep(&delay, NULL);
#endif
/*
* If we haven't already done so, arrange to have
* "pcap_close_all()" called when we exit.
*/
if (!pcap_do_addexit(handle)) {
/*
* "atexit()" failed; don't put the interface
* in rfmon mode, just give up.
*/
return PCAP_ERROR_RFMON_NOTSUP;
}
/*
* Now configure the monitor interface up.
*/
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name));
if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't get flags for %s: %s", device,
handlep->mondevice, strerror(errno));
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
ifr.ifr_flags |= IFF_UP|IFF_RUNNING;
if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't set flags for %s: %s", device,
handlep->mondevice, strerror(errno));
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
/*
* Success. Clean up the libnl state.
*/
nl80211_cleanup(&nlstate);
/*
* Note that we have to delete the monitor device when we close
* the handle.
*/
handlep->must_do_on_close |= MUST_DELETE_MONIF;
/*
* Add this to the list of pcaps to close when we exit.
*/
pcap_add_to_pcaps_to_close(handle);
return 1;
}
#endif /* HAVE_LIBNL */
static int
pcap_can_set_rfmon_linux(pcap_t *handle)
{
#ifdef HAVE_LIBNL
char phydev_path[PATH_MAX+1];
int ret;
#endif
#ifdef IW_MODE_MONITOR
int sock_fd;
struct iwreq ireq;
#endif
if (strcmp(handle->opt.source, "any") == 0) {
/*
* Monitor mode makes no sense on the "any" device.
*/
return 0;
}
#ifdef HAVE_LIBNL
/*
* Bleah. There doesn't seem to be a way to ask a mac80211
* device, through libnl, whether it supports monitor mode;
* we'll just check whether the device appears to be a
* mac80211 device and, if so, assume the device supports
* monitor mode.
*
* wmaster devices don't appear to support the Wireless
* Extensions, but we can create a mon device for a
* wmaster device, so we don't bother checking whether
* a mac80211 device supports the Wireless Extensions.
*/
ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path,
PATH_MAX);
if (ret < 0)
return ret; /* error */
if (ret == 1)
return 1; /* mac80211 device */
#endif
#ifdef IW_MODE_MONITOR
/*
* Bleah. There doesn't appear to be an ioctl to use to ask
* whether a device supports monitor mode; we'll just do
* SIOCGIWMODE and, if it succeeds, assume the device supports
* monitor mode.
*
* Open a socket on which to attempt to get the mode.
* (We assume that if we have Wireless Extensions support
* we also have PF_PACKET support.)
*/
sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (sock_fd == -1) {
(void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
return PCAP_ERROR;
}
/*
* Attempt to get the current mode.
*/
strlcpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source,
sizeof ireq.ifr_ifrn.ifrn_name);
if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) {
/*
* Well, we got the mode; assume we can set it.
*/
close(sock_fd);
return 1;
}
if (errno == ENODEV) {
/* The device doesn't even exist. */
(void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"SIOCGIWMODE failed: %s", pcap_strerror(errno));
close(sock_fd);
return PCAP_ERROR_NO_SUCH_DEVICE;
}
close(sock_fd);
#endif
return 0;
}
/*
* Grabs the number of dropped packets by the interface from /proc/net/dev.
*
* XXX - what about /sys/class/net/{interface name}/rx_*? There are
* individual devices giving, in ASCII, various rx_ and tx_ statistics.
*
* Or can we get them in binary form from netlink?
*/
static long int
linux_if_drops(const char * if_name)
{
char buffer[512];
char * bufptr;
FILE * file;
int field_to_convert = 3, if_name_sz = strlen(if_name);
long int dropped_pkts = 0;
file = fopen("/proc/net/dev", "r");
if (!file)
return 0;
while (!dropped_pkts && fgets( buffer, sizeof(buffer), file ))
{
/* search for 'bytes' -- if its in there, then
that means we need to grab the fourth field. otherwise
grab the third field. */
if (field_to_convert != 4 && strstr(buffer, "bytes"))
{
field_to_convert = 4;
continue;
}
/* find iface and make sure it actually matches -- space before the name and : after it */
if ((bufptr = strstr(buffer, if_name)) &&
(bufptr == buffer || *(bufptr-1) == ' ') &&
*(bufptr + if_name_sz) == ':')
{
bufptr = bufptr + if_name_sz + 1;
/* grab the nth field from it */
while( --field_to_convert && *bufptr != '\0')
{
while (*bufptr != '\0' && *(bufptr++) == ' ');
while (*bufptr != '\0' && *(bufptr++) != ' ');
}
/* get rid of any final spaces */
while (*bufptr != '\0' && *bufptr == ' ') bufptr++;
if (*bufptr != '\0')
dropped_pkts = strtol(bufptr, NULL, 10);
break;
}
}
fclose(file);
return dropped_pkts;
}
/*
* With older kernels promiscuous mode is kind of interesting because we
* have to reset the interface before exiting. The problem can't really
* be solved without some daemon taking care of managing usage counts.
* If we put the interface into promiscuous mode, we set a flag indicating
* that we must take it out of that mode when the interface is closed,
* and, when closing the interface, if that flag is set we take it out
* of promiscuous mode.
*
* Even with newer kernels, we have the same issue with rfmon mode.
*/
static void pcap_cleanup_linux( pcap_t *handle )
{
struct pcap_linux *handlep = handle->priv;
struct ifreq ifr;
#ifdef HAVE_LIBNL
struct nl80211_state nlstate;
int ret;
#endif /* HAVE_LIBNL */
#ifdef IW_MODE_MONITOR
int oldflags;
struct iwreq ireq;
#endif /* IW_MODE_MONITOR */
if (handlep->must_do_on_close != 0) {
/*
* There's something we have to do when closing this
* pcap_t.
*/
if (handlep->must_do_on_close & MUST_CLEAR_PROMISC) {
/*
* We put the interface into promiscuous mode;
* take it out of promiscuous mode.
*
* XXX - if somebody else wants it in promiscuous
* mode, this code cannot know that, so it'll take
* it out of promiscuous mode. That's not fixable
* in 2.0[.x] kernels.
*/
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, handlep->device,
sizeof(ifr.ifr_name));
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
fprintf(stderr,
"Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n"
"Please adjust manually.\n"
"Hint: This can't happen with Linux >= 2.2.0.\n",
handlep->device, strerror(errno));
} else {
if (ifr.ifr_flags & IFF_PROMISC) {
/*
* Promiscuous mode is currently on;
* turn it off.
*/
ifr.ifr_flags &= ~IFF_PROMISC;
if (ioctl(handle->fd, SIOCSIFFLAGS,
&ifr) == -1) {
fprintf(stderr,
"Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n"
"Please adjust manually.\n"
"Hint: This can't happen with Linux >= 2.2.0.\n",
handlep->device,
strerror(errno));
}
}
}
}
#ifdef HAVE_LIBNL
if (handlep->must_do_on_close & MUST_DELETE_MONIF) {
ret = nl80211_init(handle, &nlstate, handlep->device);
if (ret >= 0) {
ret = del_mon_if(handle, handle->fd, &nlstate,
handlep->device, handlep->mondevice);
nl80211_cleanup(&nlstate);
}
if (ret < 0) {
fprintf(stderr,
"Can't delete monitor interface %s (%s).\n"
"Please delete manually.\n",
handlep->mondevice, handle->errbuf);
}
}
#endif /* HAVE_LIBNL */
#ifdef IW_MODE_MONITOR
if (handlep->must_do_on_close & MUST_CLEAR_RFMON) {
/*
* We put the interface into rfmon mode;
* take it out of rfmon mode.
*
* XXX - if somebody else wants it in rfmon
* mode, this code cannot know that, so it'll take
* it out of rfmon mode.
*/
/*
* First, take the interface down if it's up;
* otherwise, we might get EBUSY.
* If we get errors, just drive on and print
* a warning if we can't restore the mode.
*/
oldflags = 0;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, handlep->device,
sizeof(ifr.ifr_name));
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) {
if (ifr.ifr_flags & IFF_UP) {
oldflags = ifr.ifr_flags;
ifr.ifr_flags &= ~IFF_UP;
if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1)
oldflags = 0; /* didn't set, don't restore */
}
}
/*
* Now restore the mode.
*/
strlcpy(ireq.ifr_ifrn.ifrn_name, handlep->device,
sizeof ireq.ifr_ifrn.ifrn_name);
ireq.u.mode = handlep->oldmode;
if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) {
/*
* Scientist, you've failed.
*/
fprintf(stderr,
"Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n"
"Please adjust manually.\n",
handlep->device, strerror(errno));
}
/*
* Now bring the interface back up if we brought
* it down.
*/
if (oldflags != 0) {
ifr.ifr_flags = oldflags;
if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
fprintf(stderr,
"Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n"
"Please adjust manually.\n",
handlep->device, strerror(errno));
}
}
}
#endif /* IW_MODE_MONITOR */
/*
* Take this pcap out of the list of pcaps for which we
* have to take the interface out of some mode.
*/
pcap_remove_from_pcaps_to_close(handle);
}
if (handlep->mondevice != NULL) {
free(handlep->mondevice);
handlep->mondevice = NULL;
}
if (handlep->device != NULL) {
free(handlep->device);
handlep->device = NULL;
}
pcap_cleanup_live_common(handle);
}
/*
* Get a handle for a live capture from the given device. You can
* pass NULL as device to get all packages (without link level
* information of course). If you pass 1 as promisc the interface
* will be set to promiscous mode (XXX: I think this usage should
* be deprecated and functions be added to select that later allow
* modification of that values -- Torsten).
*/
static int
pcap_activate_linux(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
const char *device;
struct ifreq ifr;
int status = 0;
int ret;
device = handle->opt.source;
/*
* Make sure the name we were handed will fit into the ioctls we
* might perform on the device; if not, return a "No such device"
* indication, as the Linux kernel shouldn't support creating
* a device whose name won't fit into those ioctls.
*
* "Will fit" means "will fit, complete with a null terminator",
* so if the length, which does *not* include the null terminator,
* is greater than *or equal to* the size of the field into which
* we'll be copying it, that won't fit.
*/
if (strlen(device) >= sizeof(ifr.ifr_name)) {
status = PCAP_ERROR_NO_SUCH_DEVICE;
goto fail;
}
handle->inject_op = pcap_inject_linux;
handle->setfilter_op = pcap_setfilter_linux;
handle->setdirection_op = pcap_setdirection_linux;
handle->set_datalink_op = pcap_set_datalink_linux;
handle->getnonblock_op = pcap_getnonblock_fd;
handle->setnonblock_op = pcap_setnonblock_fd;
handle->cleanup_op = pcap_cleanup_linux;
handle->read_op = pcap_read_linux;
handle->stats_op = pcap_stats_linux;
/*
* The "any" device is a special device which causes us not
* to bind to a particular device and thus to look at all
* devices.
*/
if (strcmp(device, "any") == 0) {
if (handle->opt.promisc) {
handle->opt.promisc = 0;
/* Just a warning. */
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Promiscuous mode not supported on the \"any\" device");
status = PCAP_WARNING_PROMISC_NOTSUP;
}
}
handlep->device = strdup(device);
if (handlep->device == NULL) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s",
pcap_strerror(errno) );
return PCAP_ERROR;
}
/* copy timeout value */
handlep->timeout = handle->opt.timeout;
/*
* If we're in promiscuous mode, then we probably want
* to see when the interface drops packets too, so get an
* initial count from /proc/net/dev
*/
if (handle->opt.promisc)
handlep->proc_dropped = linux_if_drops(handlep->device);
/*
* Current Linux kernels use the protocol family PF_PACKET to
* allow direct access to all packets on the network while
* older kernels had a special socket type SOCK_PACKET to
* implement this feature.
* While this old implementation is kind of obsolete we need
* to be compatible with older kernels for a while so we are
* trying both methods with the newer method preferred.
*/
ret = activate_new(handle);
if (ret < 0) {
/*
* Fatal error with the new way; just fail.
* ret has the error return; if it's PCAP_ERROR,
* handle->errbuf has been set appropriately.
*/
status = ret;
goto fail;
}
if (ret == 1) {
/*
* Success.
* Try to use memory-mapped access.
*/
switch (activate_mmap(handle, &status)) {
case 1:
/*
* We succeeded. status has been
* set to the status to return,
* which might be 0, or might be
* a PCAP_WARNING_ value.
*/
return status;
case 0:
/*
* Kernel doesn't support it - just continue
* with non-memory-mapped access.
*/
break;
case -1:
/*
* We failed to set up to use it, or the kernel
* supports it, but we failed to enable it.
* ret has been set to the error status to
* return and, if it's PCAP_ERROR, handle->errbuf
* contains the error message.
*/
status = ret;
goto fail;
}
}
else if (ret == 0) {
/* Non-fatal error; try old way */
if ((ret = activate_old(handle)) != 1) {
/*
* Both methods to open the packet socket failed.
* Tidy up and report our failure (handle->errbuf
* is expected to be set by the functions above).
*/
status = ret;
goto fail;
}
}
/*
* We set up the socket, but not with memory-mapped access.
*/
if (handle->opt.buffer_size != 0) {
/*
* Set the socket buffer size to the specified value.
*/
if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF,
&handle->opt.buffer_size,
sizeof(handle->opt.buffer_size)) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"SO_RCVBUF: %s", pcap_strerror(errno));
status = PCAP_ERROR;
goto fail;
}
}
/* Allocate the buffer */
handle->buffer = malloc(handle->bufsize + handle->offset);
if (!handle->buffer) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"malloc: %s", pcap_strerror(errno));
status = PCAP_ERROR;
goto fail;
}
/*
* "handle->fd" is a socket, so "select()" and "poll()"
* should work on it.
*/
handle->selectable_fd = handle->fd;
return status;
fail:
pcap_cleanup_linux(handle);
return status;
}
/*
* Read at most max_packets from the capture stream and call the callback
* for each of them. Returns the number of packets handled or -1 if an
* error occured.
*/
static int
pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
{
/*
* Currently, on Linux only one packet is delivered per read,
* so we don't loop.
*/
return pcap_read_packet(handle, callback, user);
}
static int
pcap_set_datalink_linux(pcap_t *handle, int dlt)
{
handle->linktype = dlt;
return 0;
}
/*
* linux_check_direction()
*
* Do checks based on packet direction.
*/
static inline int
linux_check_direction(const pcap_t *handle, const struct sockaddr_ll *sll)
{
struct pcap_linux *handlep = handle->priv;
if (sll->sll_pkttype == PACKET_OUTGOING) {
/*
* Outgoing packet.
* If this is from the loopback device, reject it;
* we'll see the packet as an incoming packet as well,
* and we don't want to see it twice.
*/
if (sll->sll_ifindex == handlep->lo_ifindex)
return 0;
/*
* If the user only wants incoming packets, reject it.
*/
if (handle->direction == PCAP_D_IN)
return 0;
} else {
/*
* Incoming packet.
* If the user only wants outgoing packets, reject it.
*/
if (handle->direction == PCAP_D_OUT)
return 0;
}
return 1;
}
/*
* Read a packet from the socket calling the handler provided by
* the user. Returns the number of packets received or -1 if an
* error occured.
*/
static int
pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
{
struct pcap_linux *handlep = handle->priv;
u_char *bp;
int offset;
#ifdef HAVE_PF_PACKET_SOCKETS
struct sockaddr_ll from;
struct sll_header *hdrp;
#else
struct sockaddr from;
#endif
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
union {
struct cmsghdr cmsg;
char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
} cmsg_buf;
#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
socklen_t fromlen;
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
int packet_len, caplen;
struct pcap_pkthdr pcap_header;
#ifdef HAVE_PF_PACKET_SOCKETS
/*
* If this is a cooked device, leave extra room for a
* fake packet header.
*/
if (handlep->cooked)
offset = SLL_HDR_LEN;
else
offset = 0;
#else
/*
* This system doesn't have PF_PACKET sockets, so it doesn't
* support cooked devices.
*/
offset = 0;
#endif
/*
* Receive a single packet from the kernel.
* We ignore EINTR, as that might just be due to a signal
* being delivered - if the signal should interrupt the
* loop, the signal handler should call pcap_breakloop()
* to set handle->break_loop (we ignore it on other
* platforms as well).
* We also ignore ENETDOWN, so that we can continue to
* capture traffic if the interface goes down and comes
* back up again; comments in the kernel indicate that
* we'll just block waiting for packets if we try to
* receive from a socket that delivered ENETDOWN, and,
* if we're using a memory-mapped buffer, we won't even
* get notified of "network down" events.
*/
bp = handle->buffer + handle->offset;
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
msg.msg_name = &from;
msg.msg_namelen = sizeof(from);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &cmsg_buf;
msg.msg_controllen = sizeof(cmsg_buf);
msg.msg_flags = 0;
iov.iov_len = handle->bufsize - offset;
iov.iov_base = bp + offset;
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
do {
/*
* Has "pcap_breakloop()" been called?
*/
if (handle->break_loop) {
/*
* Yes - clear the flag that indicates that it has,
* and return PCAP_ERROR_BREAK as an indication that
* we were told to break out of the loop.
*/
handle->break_loop = 0;
return PCAP_ERROR_BREAK;
}
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC);
#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
fromlen = sizeof(from);
packet_len = recvfrom(
handle->fd, bp + offset,
handle->bufsize - offset, MSG_TRUNC,
(struct sockaddr *) &from, &fromlen);
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
} while (packet_len == -1 && errno == EINTR);
/* Check if an error occured */
if (packet_len == -1) {
switch (errno) {
case EAGAIN:
return 0; /* no packet there */
case ENETDOWN:
/*
* The device on which we're capturing went away.
*
* XXX - we should really return
* PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch()
* etc. aren't defined to return that.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"The interface went down");
return PCAP_ERROR;
default:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"recvfrom: %s", pcap_strerror(errno));
return PCAP_ERROR;
}
}
#ifdef HAVE_PF_PACKET_SOCKETS
if (!handlep->sock_packet) {
/*
* Unfortunately, there is a window between socket() and
* bind() where the kernel may queue packets from any
* interface. If we're bound to a particular interface,
* discard packets not from that interface.
*
* (If socket filters are supported, we could do the
* same thing we do when changing the filter; however,
* that won't handle packet sockets without socket
* filter support, and it's a bit more complicated.
* It would save some instructions per packet, however.)
*/
if (handlep->ifindex != -1 &&
from.sll_ifindex != handlep->ifindex)
return 0;
/*
* Do checks based on packet direction.
* We can only do this if we're using PF_PACKET; the
* address returned for SOCK_PACKET is a "sockaddr_pkt"
* which lacks the relevant packet type information.
*/
if (!linux_check_direction(handle, &from))
return 0;
}
#endif
#ifdef HAVE_PF_PACKET_SOCKETS
/*
* If this is a cooked device, fill in the fake packet header.
*/
if (handlep->cooked) {
/*
* Add the length of the fake header to the length
* of packet data we read.
*/
packet_len += SLL_HDR_LEN;
hdrp = (struct sll_header *)bp;
hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype);
hdrp->sll_hatype = htons(from.sll_hatype);
hdrp->sll_halen = htons(from.sll_halen);
memcpy(hdrp->sll_addr, from.sll_addr,
(from.sll_halen > SLL_ADDRLEN) ?
SLL_ADDRLEN :
from.sll_halen);
hdrp->sll_protocol = from.sll_protocol;
}
#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
if (handlep->vlan_offset != -1) {
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
struct tpacket_auxdata *aux;
unsigned int len;
struct vlan_tag *tag;
if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) ||
cmsg->cmsg_level != SOL_PACKET ||
cmsg->cmsg_type != PACKET_AUXDATA)
continue;
aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
#if defined(TP_STATUS_VLAN_VALID)
if ((aux->tp_vlan_tci == 0) && !(aux->tp_status & TP_STATUS_VLAN_VALID))
#else
if (aux->tp_vlan_tci == 0) /* this is ambigious but without the
TP_STATUS_VLAN_VALID flag, there is
nothing that we can do */
#endif
continue;
len = packet_len > iov.iov_len ? iov.iov_len : packet_len;
if (len < (unsigned int) handlep->vlan_offset)
break;
bp -= VLAN_TAG_LEN;
memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset);
tag = (struct vlan_tag *)(bp + handlep->vlan_offset);
tag->vlan_tpid = htons(ETH_P_8021Q);
tag->vlan_tci = htons(aux->tp_vlan_tci);
packet_len += VLAN_TAG_LEN;
}
}
#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
#endif /* HAVE_PF_PACKET_SOCKETS */
/*
* XXX: According to the kernel source we should get the real
* packet len if calling recvfrom with MSG_TRUNC set. It does
* not seem to work here :(, but it is supported by this code
* anyway.
* To be honest the code RELIES on that feature so this is really
* broken with 2.2.x kernels.
* I spend a day to figure out what's going on and I found out
* that the following is happening:
*
* The packet comes from a random interface and the packet_rcv
* hook is called with a clone of the packet. That code inserts
* the packet into the receive queue of the packet socket.
* If a filter is attached to that socket that filter is run
* first - and there lies the problem. The default filter always
* cuts the packet at the snaplen:
*
* # tcpdump -d
* (000) ret #68
*
* So the packet filter cuts down the packet. The recvfrom call
* says "hey, it's only 68 bytes, it fits into the buffer" with
* the result that we don't get the real packet length. This
* is valid at least until kernel 2.2.17pre6.
*
* We currently handle this by making a copy of the filter
* program, fixing all "ret" instructions with non-zero
* operands to have an operand of MAXIMUM_SNAPLEN so that the
* filter doesn't truncate the packet, and supplying that modified
* filter to the kernel.
*/
caplen = packet_len;
if (caplen > handle->snapshot)
caplen = handle->snapshot;
/* Run the packet filter if not using kernel filter */
if (handlep->filter_in_userland && handle->fcode.bf_insns) {
if (bpf_filter(handle->fcode.bf_insns, bp,
packet_len, caplen) == 0)
{
/* rejected by filter */
return 0;
}
}
/* Fill in our own header data */
/* get timestamp for this packet */
#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS)
if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) {
if (ioctl(handle->fd, SIOCGSTAMPNS, &pcap_header.ts) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"SIOCGSTAMPNS: %s", pcap_strerror(errno));
return PCAP_ERROR;
}
} else
#endif
{
if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"SIOCGSTAMP: %s", pcap_strerror(errno));
return PCAP_ERROR;
}
}
pcap_header.caplen = caplen;
pcap_header.len = packet_len;
/*
* Count the packet.
*
* Arguably, we should count them before we check the filter,
* as on many other platforms "ps_recv" counts packets
* handed to the filter rather than packets that passed
* the filter, but if filtering is done in the kernel, we
* can't get a count of packets that passed the filter,
* and that would mean the meaning of "ps_recv" wouldn't
* be the same on all Linux systems.
*
* XXX - it's not the same on all systems in any case;
* ideally, we should have a "get the statistics" call
* that supplies more counts and indicates which of them
* it supplies, so that we supply a count of packets
* handed to the filter only on platforms where that
* information is available.
*
* We count them here even if we can get the packet count
* from the kernel, as we can only determine at run time
* whether we'll be able to get it from the kernel (if
* HAVE_TPACKET_STATS isn't defined, we can't get it from
* the kernel, but if it is defined, the library might
* have been built with a 2.4 or later kernel, but we
* might be running on a 2.2[.x] kernel without Alexey
* Kuznetzov's turbopacket patches, and thus the kernel
* might not be able to supply those statistics). We
* could, I guess, try, when opening the socket, to get
* the statistics, and if we can not increment the count
* here, but it's not clear that always incrementing
* the count is more expensive than always testing a flag
* in memory.
*
* We keep the count in "handlep->packets_read", and use that
* for "ps_recv" if we can't get the statistics from the kernel.
* We do that because, if we *can* get the statistics from
* the kernel, we use "handlep->stat.ps_recv" and
* "handlep->stat.ps_drop" as running counts, as reading the
* statistics from the kernel resets the kernel statistics,
* and if we directly increment "handlep->stat.ps_recv" here,
* that means it will count packets *twice* on systems where
* we can get kernel statistics - once here, and once in
* pcap_stats_linux().
*/
handlep->packets_read++;
/* Call the user supplied callback function */
callback(userdata, &pcap_header, bp);
return 1;
}
static int
pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
{
struct pcap_linux *handlep = handle->priv;
int ret;
#ifdef HAVE_PF_PACKET_SOCKETS
if (!handlep->sock_packet) {
/* PF_PACKET socket */
if (handlep->ifindex == -1) {
/*
* We don't support sending on the "any" device.
*/
strlcpy(handle->errbuf,
"Sending packets isn't supported on the \"any\" device",
PCAP_ERRBUF_SIZE);
return (-1);
}
if (handlep->cooked) {
/*
* We don't support sending on the "any" device.
*
* XXX - how do you send on a bound cooked-mode
* socket?
* Is a "sendto()" required there?
*/
strlcpy(handle->errbuf,
"Sending packets isn't supported in cooked mode",
PCAP_ERRBUF_SIZE);
return (-1);
}
}
#endif
ret = send(handle->fd, buf, size, 0);
if (ret == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
pcap_strerror(errno));
return (-1);
}
return (ret);
}
/*
* Get the statistics for the given packet capture handle.
* Reports the number of dropped packets iff the kernel supports
* the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
* kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
* patches); otherwise, that information isn't available, and we lie
* and report 0 as the count of dropped packets.
*/
static int
pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
{
struct pcap_linux *handlep = handle->priv;
#ifdef HAVE_TPACKET_STATS
#ifdef HAVE_TPACKET3
/*
* For sockets using TPACKET_V1 or TPACKET_V2, the extra
* stuff at the end of a struct tpacket_stats_v3 will not
* be filled in, and we don't look at it so this is OK even
* for those sockets. In addition, the PF_PACKET socket
* code in the kernel only uses the length parameter to
* compute how much data to copy out and to indicate how
* much data was copied out, so it's OK to base it on the
* size of a struct tpacket_stats.
*
* XXX - it's probably OK, in fact, to just use a
* struct tpacket_stats for V3 sockets, as we don't
* care about the tp_freeze_q_cnt stat.
*/
struct tpacket_stats_v3 kstats;
#else /* HAVE_TPACKET3 */
struct tpacket_stats kstats;
#endif /* HAVE_TPACKET3 */
socklen_t len = sizeof (struct tpacket_stats);
#endif /* HAVE_TPACKET_STATS */
long if_dropped = 0;
/*
* To fill in ps_ifdrop, we parse /proc/net/dev for the number
*/
if (handle->opt.promisc)
{
if_dropped = handlep->proc_dropped;
handlep->proc_dropped = linux_if_drops(handlep->device);
handlep->stat.ps_ifdrop += (handlep->proc_dropped - if_dropped);
}
#ifdef HAVE_TPACKET_STATS
/*
* Try to get the packet counts from the kernel.
*/
if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
&kstats, &len) > -1) {
/*
* On systems where the PACKET_STATISTICS "getsockopt()"
* argument is supported on PF_PACKET sockets:
*
* "ps_recv" counts only packets that *passed* the
* filter, not packets that didn't pass the filter.
* This includes packets later dropped because we
* ran out of buffer space.
*
* "ps_drop" counts packets dropped 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.
*
* See above for ps_ifdrop.
*
* Both statistics include packets not yet read from
* the kernel by libpcap, and thus not yet seen by
* the application.
*
* In "linux/net/packet/af_packet.c", at least in the
* 2.4.9 kernel, "tp_packets" is incremented for every
* packet that passes the packet filter *and* is
* successfully queued on the socket; "tp_drops" is
* incremented for every packet dropped because there's
* not enough free space in the socket buffer.
*
* When the statistics are returned for a PACKET_STATISTICS
* "getsockopt()" call, "tp_drops" is added to "tp_packets",
* so that "tp_packets" counts all packets handed to
* the PF_PACKET socket, including packets dropped because
* there wasn't room on the socket buffer - but not
* including packets that didn't pass the filter.
*
* In the BSD BPF, the count of received packets is
* incremented for every packet handed to BPF, regardless
* of whether it passed the filter.
*
* We can't make "pcap_stats()" work the same on both
* platforms, but the best approximation is to return
* "tp_packets" as the count of packets and "tp_drops"
* as the count of drops.
*
* Keep a running total because each call to
* getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
* resets the counters to zero.
*/
handlep->stat.ps_recv += kstats.tp_packets;
handlep->stat.ps_drop += kstats.tp_drops;
*stats = handlep->stat;
return 0;
}
else
{
/*
* If the error was EOPNOTSUPP, fall through, so that
* if you build the library on a system with
* "struct tpacket_stats" and run it on a system
* that doesn't, it works as it does if the library
* is built on a system without "struct tpacket_stats".
*/
if (errno != EOPNOTSUPP) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"pcap_stats: %s", pcap_strerror(errno));
return -1;
}
}
#endif
/*
* On systems where the PACKET_STATISTICS "getsockopt()" argument
* is not supported on PF_PACKET sockets:
*
* "ps_recv" counts only packets that *passed* the filter,
* not packets that didn't pass the filter. It does not
* count packets dropped because we ran out of buffer
* space.
*
* "ps_drop" is not supported.
*
* "ps_ifdrop" is supported. It will return the number
* of drops the interface reports in /proc/net/dev,
* if that is available.
*
* "ps_recv" doesn't include packets not yet read from
* the kernel by libpcap.
*
* We maintain the count of packets processed by libpcap in
* "handlep->packets_read", for reasons described in the comment
* at the end of pcap_read_packet(). We have no idea how many
* packets were dropped by the kernel buffers -- but we know
* how many the interface dropped, so we can return that.
*/
stats->ps_recv = handlep->packets_read;
stats->ps_drop = 0;
stats->ps_ifdrop = handlep->stat.ps_ifdrop;
return 0;
}
static int
add_linux_if(pcap_if_t **devlistp, const char *ifname, int fd, char *errbuf)
{
const char *p;
char name[512]; /* XXX - pick a size */
char *q, *saveq;
struct ifreq ifrflags;
/*
* Get the interface name.
*/
p = ifname;
q = &name[0];
while (*p != '\0' && isascii(*p) && !isspace(*p)) {
if (*p == ':') {
/*
* This could be the separator between a
* name and an alias number, or it could be
* the separator between a name with no
* alias number and the next field.
*
* If there's a colon after digits, it
* separates the name and the alias number,
* otherwise it separates the name and the
* next field.
*/
saveq = q;
while (isascii(*p) && isdigit(*p))
*q++ = *p++;
if (*p != ':') {
/*
* That was the next field,
* not the alias number.
*/
q = saveq;
}
break;
} else
*q++ = *p++;
}
*q = '\0';
/*
* Get the flags for this interface.
*/
strlcpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
if (errno == ENXIO || errno == ENODEV)
return (0); /* device doesn't actually exist - ignore it */
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"SIOCGIFFLAGS: %.*s: %s",
(int)sizeof(ifrflags.ifr_name),
ifrflags.ifr_name,
pcap_strerror(errno));
return (-1);
}
/*
* Add an entry for this interface, with no addresses.
*/
if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
errbuf) == -1) {
/*
* Failure.
*/
return (-1);
}
return (0);
}
/*
* Get from "/sys/class/net" all interfaces listed there; if they're
* already in the list of interfaces we have, that won't add another
* instance, but if they're not, that'll add them.
*
* We don't bother getting any addresses for them; it appears you can't
* use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
* although some other types of addresses can be fetched with SIOCGIFADDR,
* we don't bother with them for now.
*
* We also don't fail if we couldn't open "/sys/class/net"; we just leave
* the list of interfaces as is, and return 0, so that we can try
* scanning /proc/net/dev.
*
* Otherwise, we return 1 if we don't get an error and -1 if we do.
*/
static int
scan_sys_class_net(pcap_if_t **devlistp, char *errbuf)
{
DIR *sys_class_net_d;
int fd;
struct dirent *ent;
char subsystem_path[PATH_MAX+1];
struct stat statb;
int ret = 1;
sys_class_net_d = opendir("/sys/class/net");
if (sys_class_net_d == NULL) {
/*
* Don't fail if it doesn't exist at all.
*/
if (errno == ENOENT)
return (0);
/*
* Fail if we got some other error.
*/
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Can't open /sys/class/net: %s", pcap_strerror(errno));
return (-1);
}
/*
* Create a socket from which to fetch interface information.
*/
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
(void)closedir(sys_class_net_d);
return (-1);
}
for (;;) {
errno = 0;
ent = readdir(sys_class_net_d);
if (ent == NULL) {
/*
* Error or EOF; if errno != 0, it's an error.
*/
break;
}
/*
* Ignore "." and "..".
*/
if (strcmp(ent->d_name, ".") == 0 ||
strcmp(ent->d_name, "..") == 0)
continue;
/*
* Ignore plain files; they do not have subdirectories
* and thus have no attributes.
*/
if (ent->d_type == DT_REG)
continue;
/*
* Is there an "ifindex" file under that name?
* (We don't care whether it's a directory or
* a symlink; older kernels have directories
* for devices, newer kernels have symlinks to
* directories.)
*/
snprintf(subsystem_path, sizeof subsystem_path,
"/sys/class/net/%s/ifindex", ent->d_name);
if (lstat(subsystem_path, &statb) != 0) {
/*
* Stat failed. Either there was an error
* other than ENOENT, and we don't know if
* this is an interface, or it's ENOENT,
* and either some part of "/sys/class/net/{if}"
* disappeared, in which case it probably means
* the interface disappeared, or there's no
* "ifindex" file, which means it's not a
* network interface.
*/
continue;
}
/*
* Attempt to add the interface.
*/
if (add_linux_if(devlistp, &ent->d_name[0], fd, errbuf) == -1) {
/* Fail. */
ret = -1;
break;
}
}
if (ret != -1) {
/*
* Well, we didn't fail for any other reason; did we
* fail due to an error reading the directory?
*/
if (errno != 0) {
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Error reading /sys/class/net: %s",
pcap_strerror(errno));
ret = -1;
}
}
(void)close(fd);
(void)closedir(sys_class_net_d);
return (ret);
}
/*
* Get from "/proc/net/dev" all interfaces listed there; if they're
* already in the list of interfaces we have, that won't add another
* instance, but if they're not, that'll add them.
*
* See comments from scan_sys_class_net().
*/
static int
scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf)
{
FILE *proc_net_f;
int fd;
char linebuf[512];
int linenum;
char *p;
int ret = 0;
proc_net_f = fopen("/proc/net/dev", "r");
if (proc_net_f == NULL) {
/*
* Don't fail if it doesn't exist at all.
*/
if (errno == ENOENT)
return (0);
/*
* Fail if we got some other error.
*/
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Can't open /proc/net/dev: %s", pcap_strerror(errno));
return (-1);
}
/*
* Create a socket from which to fetch interface information.
*/
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
(void)fclose(proc_net_f);
return (-1);
}
for (linenum = 1;
fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
/*
* Skip the first two lines - they're headers.
*/
if (linenum <= 2)
continue;
p = &linebuf[0];
/*
* Skip leading white space.
*/
while (*p != '\0' && isascii(*p) && isspace(*p))
p++;
if (*p == '\0' || *p == '\n')
continue; /* blank line */
/*
* Attempt to add the interface.
*/
if (add_linux_if(devlistp, p, fd, errbuf) == -1) {
/* Fail. */
ret = -1;
break;
}
}
if (ret != -1) {
/*
* Well, we didn't fail for any other reason; did we
* fail due to an error reading the file?
*/
if (ferror(proc_net_f)) {
(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Error reading /proc/net/dev: %s",
pcap_strerror(errno));
ret = -1;
}
}
(void)close(fd);
(void)fclose(proc_net_f);
return (ret);
}
/*
* Description string for the "any" device.
*/
static const char any_descr[] = "Pseudo-device that captures on all interfaces";
int
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
{
int ret;
/*
* Read "/sys/class/net", and add to the list of interfaces all
* interfaces listed there that we don't already have, because,
* on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses,
* and even getifaddrs() won't return information about
* interfaces with no addresses, so you need to read "/sys/class/net"
* to get the names of the rest of the interfaces.
*/
ret = scan_sys_class_net(alldevsp, errbuf);
if (ret == -1)
return (-1); /* failed */
if (ret == 0) {
/*
* No /sys/class/net; try reading /proc/net/dev instead.
*/
if (scan_proc_net_dev(alldevsp, errbuf) == -1)
return (-1);
}
/*
* Add the "any" device.
*/
if (pcap_add_if(alldevsp, "any", IFF_UP|IFF_RUNNING,
any_descr, errbuf) < 0)
return (-1);
return (0);
}
/*
* Attach the given BPF code to the packet capture device.
*/
static int
pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter,
int is_mmapped)
{
struct pcap_linux *handlep;
#ifdef SO_ATTACH_FILTER
struct sock_fprog fcode;
int can_filter_in_kernel;
int err = 0;
#endif
if (!handle)
return -1;
if (!filter) {
strlcpy(handle->errbuf, "setfilter: No filter specified",
PCAP_ERRBUF_SIZE);
return -1;
}
handlep = handle->priv;
/* Make our private copy of the filter */
if (install_bpf_program(handle, filter) < 0)
/* install_bpf_program() filled in errbuf */
return -1;
/*
* Run user level packet filter by default. Will be overriden if
* installing a kernel filter succeeds.
*/
handlep->filter_in_userland = 1;
/* Install kernel level filter if possible */
#ifdef SO_ATTACH_FILTER
#ifdef USHRT_MAX
if (handle->fcode.bf_len > USHRT_MAX) {
/*
* fcode.len is an unsigned short for current kernel.
* I have yet to see BPF-Code with that much
* instructions but still it is possible. So for the
* sake of correctness I added this check.
*/
fprintf(stderr, "Warning: Filter too complex for kernel\n");
fcode.len = 0;
fcode.filter = NULL;
can_filter_in_kernel = 0;
} else
#endif /* USHRT_MAX */
{
/*
* Oh joy, the Linux kernel uses struct sock_fprog instead
* of struct bpf_program and of course the length field is
* of different size. Pointed out by Sebastian
*
* Oh, and we also need to fix it up so that all "ret"
* instructions with non-zero operands have MAXIMUM_SNAPLEN
* as the operand if we're not capturing in memory-mapped
* mode, and so that, if we're in cooked mode, all memory-
* reference instructions use special magic offsets in
* references to the link-layer header and assume that the
* link-layer payload begins at 0; "fix_program()" will do
* that.
*/
switch (fix_program(handle, &fcode, is_mmapped)) {
case -1:
default:
/*
* Fatal error; just quit.
* (The "default" case shouldn't happen; we
* return -1 for that reason.)
*/
return -1;
case 0:
/*
* The program performed checks that we can't make
* work in the kernel.
*/
can_filter_in_kernel = 0;
break;
case 1:
/*
* We have a filter that'll work in the kernel.
*/
can_filter_in_kernel = 1;
break;
}
}
/*
* NOTE: at this point, we've set both the "len" and "filter"
* fields of "fcode". As of the 2.6.32.4 kernel, at least,
* those are the only members of the "sock_fprog" structure,
* so we initialize every member of that structure.
*
* If there is anything in "fcode" that is not initialized,
* it is either a field added in a later kernel, or it's
* padding.
*
* If a new field is added, this code needs to be updated
* to set it correctly.
*
* If there are no other fields, then:
*
* if the Linux kernel looks at the padding, it's
* buggy;
*
* if the Linux kernel doesn't look at the padding,
* then if some tool complains that we're passing
* uninitialized data to the kernel, then the tool
* is buggy and needs to understand that it's just
* padding.
*/
if (can_filter_in_kernel) {
if ((err = set_kernel_filter(handle, &fcode)) == 0)
{
/*
* Installation succeded - using kernel filter,
* so userland filtering not needed.
*/
handlep->filter_in_userland = 0;
}
else if (err == -1) /* Non-fatal error */
{
/*
* Print a warning if we weren't able to install
* the filter for a reason other than "this kernel
* isn't configured to support socket filters.
*/
if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
fprintf(stderr,
"Warning: Kernel filter failed: %s\n",
pcap_strerror(errno));
}
}
}
/*
* If we're not using the kernel filter, get rid of any kernel
* filter that might've been there before, e.g. because the
* previous filter could work in the kernel, or because some other
* code attached a filter to the socket by some means other than
* calling "pcap_setfilter()". Otherwise, the kernel filter may
* filter out packets that would pass the new userland filter.
*/
if (handlep->filter_in_userland) {
if (reset_kernel_filter(handle) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't remove kernel filter: %s",
pcap_strerror(errno));
err = -2; /* fatal error */
}
}
/*
* Free up the copy of the filter that was made by "fix_program()".
*/
if (fcode.filter != NULL)
free(fcode.filter);
if (err == -2)
/* Fatal error */
return -1;
#endif /* SO_ATTACH_FILTER */
return 0;
}
static int
pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
{
return pcap_setfilter_linux_common(handle, filter, 0);
}
/*
* Set direction flag: Which packets do we accept on a forwarding
* single device? IN, OUT or both?
*/
static int
pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
{
#ifdef HAVE_PF_PACKET_SOCKETS
struct pcap_linux *handlep = handle->priv;
if (!handlep->sock_packet) {
handle->direction = d;
return 0;
}
#endif
/*
* We're not using PF_PACKET sockets, so we can't determine
* the direction of the packet.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Setting direction is not supported on SOCK_PACKET sockets");
return -1;
}
#ifdef HAVE_PF_PACKET_SOCKETS
/*
* Map the PACKET_ value to a LINUX_SLL_ value; we
* want the same numerical value to be used in
* the link-layer header even if the numerical values
* for the PACKET_ #defines change, so that programs
* that look at the packet type field will always be
* able to handle DLT_LINUX_SLL captures.
*/
static short int
map_packet_type_to_sll_type(short int sll_pkttype)
{
switch (sll_pkttype) {
case PACKET_HOST:
return htons(LINUX_SLL_HOST);
case PACKET_BROADCAST:
return htons(LINUX_SLL_BROADCAST);
case PACKET_MULTICAST:
return htons(LINUX_SLL_MULTICAST);
case PACKET_OTHERHOST:
return htons(LINUX_SLL_OTHERHOST);
case PACKET_OUTGOING:
return htons(LINUX_SLL_OUTGOING);
default:
return -1;
}
}
#endif
/*
* Linux uses the ARP hardware type to identify the type of an
* interface. pcap uses the DLT_xxx constants for this. This
* function takes a pointer to a "pcap_t", and an ARPHRD_xxx
* constant, as arguments, and sets "handle->linktype" to the
* appropriate DLT_XXX constant and sets "handle->offset" to
* the appropriate value (to make "handle->offset" plus link-layer
* header length be a multiple of 4, so that the link-layer payload
* will be aligned on a 4-byte boundary when capturing packets).
* (If the offset isn't set here, it'll be 0; add code as appropriate
* for cases where it shouldn't be 0.)
*
* If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
* in cooked mode; otherwise, we can't use cooked mode, so we have
* to pick some type that works in raw mode, or fail.
*
* Sets the link type to -1 if unable to map the type.
*/
static void map_arphrd_to_dlt(pcap_t *handle, int arptype, const char *device,
int cooked_ok)
{
static const char cdma_rmnet[] = "cdma_rmnet";
switch (arptype) {
case ARPHRD_ETHER:
/*
* For various annoying reasons having to do with DHCP
* software, some versions of Android give the mobile-
* phone-network interface an ARPHRD_ value of
* ARPHRD_ETHER, even though the packet supplied by
* that interface have no link-layer header, and begin
* with an IP header, so that the ARPHRD_ value should
* be ARPHRD_NONE.
*
* Detect those devices by checking the device name, and
* use DLT_RAW for them.
*/
if (strncmp(device, cdma_rmnet, sizeof cdma_rmnet - 1) == 0) {
handle->linktype = DLT_RAW;
return;
}
/*
* This is (presumably) a real Ethernet capture; give it a
* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, 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).
*
* XXX - are there any sorts of "fake Ethernet" that have
* ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
* a Cisco CMTS won't put traffic onto it or get traffic
* bridged onto it? ISDN is handled in "activate_new()",
* as we fall back on cooked mode there; are there any
* others?
*/
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
/*
* If that fails, just leave the list empty.
*/
if (handle->dlt_list != NULL) {
handle->dlt_list[0] = DLT_EN10MB;
handle->dlt_list[1] = DLT_DOCSIS;
handle->dlt_count = 2;
}
/* FALLTHROUGH */
case ARPHRD_METRICOM:
case ARPHRD_LOOPBACK:
handle->linktype = DLT_EN10MB;
handle->offset = 2;
break;
case ARPHRD_EETHER:
handle->linktype = DLT_EN3MB;
break;
case ARPHRD_AX25:
handle->linktype = DLT_AX25_KISS;
break;
case ARPHRD_PRONET:
handle->linktype = DLT_PRONET;
break;
case ARPHRD_CHAOS:
handle->linktype = DLT_CHAOS;
break;
#ifndef ARPHRD_CAN
#define ARPHRD_CAN 280
#endif
case ARPHRD_CAN:
handle->linktype = DLT_CAN_SOCKETCAN;
break;
#ifndef ARPHRD_IEEE802_TR
#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
#endif
case ARPHRD_IEEE802_TR:
case ARPHRD_IEEE802:
handle->linktype = DLT_IEEE802;
handle->offset = 2;
break;
case ARPHRD_ARCNET:
handle->linktype = DLT_ARCNET_LINUX;
break;
#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
#define ARPHRD_FDDI 774
#endif
case ARPHRD_FDDI:
handle->linktype = DLT_FDDI;
handle->offset = 3;
break;
#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
#define ARPHRD_ATM 19
#endif
case ARPHRD_ATM:
/*
* The Classical IP implementation in ATM for Linux
* supports both what RFC 1483 calls "LLC Encapsulation",
* in which each packet has an LLC header, possibly
* with a SNAP header as well, prepended to it, and
* what RFC 1483 calls "VC Based Multiplexing", in which
* different virtual circuits carry different network
* layer protocols, and no header is prepended to packets.
*
* They both have an ARPHRD_ type of ARPHRD_ATM, so
* you can't use the ARPHRD_ type to find out whether
* captured packets will have an LLC header, and,
* while there's a socket ioctl to *set* the encapsulation
* type, there's no ioctl to *get* the encapsulation type.
*
* This means that
*
* programs that dissect Linux Classical IP frames
* would have to check for an LLC header and,
* depending on whether they see one or not, dissect
* the frame as LLC-encapsulated or as raw IP (I
* don't know whether there's any traffic other than
* IP that would show up on the socket, or whether
* there's any support for IPv6 in the Linux
* Classical IP code);
*
* filter expressions would have to compile into
* code that checks for an LLC header and does
* the right thing.
*
* Both of those are a nuisance - and, at least on systems
* that support PF_PACKET sockets, we don't have to put
* up with those nuisances; instead, we can just capture
* in cooked mode. That's what we'll do, if we can.
* Otherwise, we'll just fail.
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else
handle->linktype = -1;
break;
#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
#define ARPHRD_IEEE80211 801
#endif
case ARPHRD_IEEE80211:
handle->linktype = DLT_IEEE802_11;
break;
#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
#define ARPHRD_IEEE80211_PRISM 802
#endif
case ARPHRD_IEEE80211_PRISM:
handle->linktype = DLT_PRISM_HEADER;
break;
#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
#define ARPHRD_IEEE80211_RADIOTAP 803
#endif
case ARPHRD_IEEE80211_RADIOTAP:
handle->linktype = DLT_IEEE802_11_RADIO;
break;
case ARPHRD_PPP:
/*
* Some PPP code in the kernel supplies no link-layer
* header whatsoever to PF_PACKET sockets; other PPP
* code supplies PPP link-layer headers ("syncppp.c");
* some PPP code might supply random link-layer
* headers (PPP over ISDN - there's code in Ethereal,
* for example, to cope with PPP-over-ISDN captures
* with which the Ethereal developers have had to cope,
* heuristically trying to determine which of the
* oddball link-layer headers particular packets have).
*
* As such, we just punt, and run all PPP interfaces
* in cooked mode, if we can; otherwise, we just treat
* it as DLT_RAW, for now - if somebody needs to capture,
* on a 2.0[.x] kernel, on PPP devices that supply a
* link-layer header, they'll have to add code here to
* map to the appropriate DLT_ type (possibly adding a
* new DLT_ type, if necessary).
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else {
/*
* XXX - handle ISDN types here? We can't fall
* back on cooked sockets, so we'd have to
* figure out from the device name what type of
* link-layer encapsulation it's using, and map
* that to an appropriate DLT_ value, meaning
* we'd map "isdnN" devices to DLT_RAW (they
* supply raw IP packets with no link-layer
* header) and "isdY" devices to a new DLT_I4L_IP
* type that has only an Ethernet packet type as
* a link-layer header.
*
* But sometimes we seem to get random crap
* in the link-layer header when capturing on
* ISDN devices....
*/
handle->linktype = DLT_RAW;
}
break;
#ifndef ARPHRD_CISCO
#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
#endif
case ARPHRD_CISCO:
handle->linktype = DLT_C_HDLC;
break;
/* Not sure if this is correct for all tunnels, but it
* works for CIPE */
case ARPHRD_TUNNEL:
#ifndef ARPHRD_SIT
#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
#endif
case ARPHRD_SIT:
case ARPHRD_CSLIP:
case ARPHRD_SLIP6:
case ARPHRD_CSLIP6:
case ARPHRD_ADAPT:
case ARPHRD_SLIP:
#ifndef ARPHRD_RAWHDLC
#define ARPHRD_RAWHDLC 518
#endif
case ARPHRD_RAWHDLC:
#ifndef ARPHRD_DLCI
#define ARPHRD_DLCI 15
#endif
case ARPHRD_DLCI:
/*
* XXX - should some of those be mapped to DLT_LINUX_SLL
* instead? Should we just map all of them to DLT_LINUX_SLL?
*/
handle->linktype = DLT_RAW;
break;
#ifndef ARPHRD_FRAD
#define ARPHRD_FRAD 770
#endif
case ARPHRD_FRAD:
handle->linktype = DLT_FRELAY;
break;
case ARPHRD_LOCALTLK:
handle->linktype = DLT_LTALK;
break;
case 18:
/*
* RFC 4338 defines an encapsulation for IP and ARP
* packets that's compatible with the RFC 2625
* encapsulation, but that uses a different ARP
* hardware type and hardware addresses. That
* ARP hardware type is 18; Linux doesn't define
* any ARPHRD_ value as 18, but if it ever officially
* supports RFC 4338-style IP-over-FC, it should define
* one.
*
* For now, we map it to DLT_IP_OVER_FC, in the hopes
* that this will encourage its use in the future,
* should Linux ever officially support RFC 4338-style
* IP-over-FC.
*/
handle->linktype = DLT_IP_OVER_FC;
break;
#ifndef ARPHRD_FCPP
#define ARPHRD_FCPP 784
#endif
case ARPHRD_FCPP:
#ifndef ARPHRD_FCAL
#define ARPHRD_FCAL 785
#endif
case ARPHRD_FCAL:
#ifndef ARPHRD_FCPL
#define ARPHRD_FCPL 786
#endif
case ARPHRD_FCPL:
#ifndef ARPHRD_FCFABRIC
#define ARPHRD_FCFABRIC 787
#endif
case ARPHRD_FCFABRIC:
/*
* Back in 2002, Donald Lee at Cray wanted a DLT_ for
* IP-over-FC:
*
* http://www.mail-archive.com/tcpdump-workers@sandelman.ottawa.on.ca/msg01043.html
*
* and one was assigned.
*
* In a later private discussion (spun off from a message
* on the ethereal-users list) on how to get that DLT_
* value in libpcap on Linux, I ended up deciding that
* the best thing to do would be to have him tweak the
* driver to set the ARPHRD_ value to some ARPHRD_FCxx
* type, and map all those types to DLT_IP_OVER_FC:
*
* I've checked into the libpcap and tcpdump CVS tree
* support for DLT_IP_OVER_FC. In order to use that,
* you'd have to modify your modified driver to return
* one of the ARPHRD_FCxxx types, in "fcLINUXfcp.c" -
* change it to set "dev->type" to ARPHRD_FCFABRIC, for
* example (the exact value doesn't matter, it can be
* any of ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL, or
* ARPHRD_FCFABRIC).
*
* 11 years later, Christian Svensson wanted to map
* various ARPHRD_ values to DLT_FC_2 and
* DLT_FC_2_WITH_FRAME_DELIMS for raw Fibre Channel
* frames:
*
* https://github.com/mcr/libpcap/pull/29
*
* There doesn't seem to be any network drivers that uses
* any of the ARPHRD_FC* values for IP-over-FC, and
* it's not exactly clear what the "Dummy types for non
* ARP hardware" are supposed to mean (link-layer
* header type? Physical network type?), so it's
* not exactly clear why the ARPHRD_FC* types exist
* in the first place.
*
* For now, we map them to DLT_FC_2, and provide an
* option of DLT_FC_2_WITH_FRAME_DELIMS, as well as
* DLT_IP_OVER_FC just in case there's some old
* driver out there that uses one of those types for
* IP-over-FC on which somebody wants to capture
* packets.
*/
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
/*
* If that fails, just leave the list empty.
*/
if (handle->dlt_list != NULL) {
handle->dlt_list[0] = DLT_FC_2;
handle->dlt_list[1] = DLT_FC_2_WITH_FRAME_DELIMS;
handle->dlt_list[2] = DLT_IP_OVER_FC;
handle->dlt_count = 3;
}
handle->linktype = DLT_FC_2;
break;
#ifndef ARPHRD_IRDA
#define ARPHRD_IRDA 783
#endif
case ARPHRD_IRDA:
/* Don't expect IP packet out of this interfaces... */
handle->linktype = DLT_LINUX_IRDA;
/* We need to save packet direction for IrDA decoding,
* so let's use "Linux-cooked" mode. Jean II
*
* XXX - this is handled in activate_new(). */
//handlep->cooked = 1;
break;
/* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
* is needed, please report it to <daniele@orlandi.com> */
#ifndef ARPHRD_LAPD
#define ARPHRD_LAPD 8445
#endif
case ARPHRD_LAPD:
/* Don't expect IP packet out of this interfaces... */
handle->linktype = DLT_LINUX_LAPD;
break;
#ifndef ARPHRD_NONE
#define ARPHRD_NONE 0xFFFE
#endif
case ARPHRD_NONE:
/*
* No link-layer header; packets are just IP
* packets, so use DLT_RAW.
*/
handle->linktype = DLT_RAW;
break;
#ifndef ARPHRD_IEEE802154
#define ARPHRD_IEEE802154 804
#endif
case ARPHRD_IEEE802154:
handle->linktype = DLT_IEEE802_15_4_NOFCS;
break;
#ifndef ARPHRD_NETLINK
#define ARPHRD_NETLINK 824
#endif
case ARPHRD_NETLINK:
handle->linktype = DLT_NETLINK;
/*
* We need to use cooked mode, so that in sll_protocol we
* pick up the netlink protocol type such as NETLINK_ROUTE,
* NETLINK_GENERIC, NETLINK_FIB_LOOKUP, etc.
*
* XXX - this is handled in activate_new().
*/
//handlep->cooked = 1;
break;
default:
handle->linktype = -1;
break;
}
}
/* ===== Functions to interface to the newer kernels ================== */
/*
* Try to open a packet socket using the new kernel PF_PACKET interface.
* Returns 1 on success, 0 on an error that means the new interface isn't
* present (so the old SOCK_PACKET interface should be tried), and a
* PCAP_ERROR_ value on an error that means that the old mechanism won't
* work either (so it shouldn't be tried).
*/
static int
activate_new(pcap_t *handle)
{
#ifdef HAVE_PF_PACKET_SOCKETS
struct pcap_linux *handlep = handle->priv;
const char *device = handle->opt.source;
int is_any_device = (strcmp(device, "any") == 0);
int sock_fd = -1, arptype;
#ifdef HAVE_PACKET_AUXDATA
int val;
#endif
int err = 0;
struct packet_mreq mr;
/*
* Open a socket with protocol family packet. If the
* "any" device was specified, we open a SOCK_DGRAM
* socket for the cooked interface, otherwise we first
* try a SOCK_RAW socket for the raw interface.
*/
sock_fd = is_any_device ?
socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) :
socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (sock_fd == -1) {
if (errno == EINVAL || errno == EAFNOSUPPORT) {
/*
* We don't support PF_PACKET/SOCK_whatever
* sockets; try the old mechanism.
*/
return 0;
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
pcap_strerror(errno) );
if (errno == EPERM || errno == EACCES) {
/*
* You don't have permission to open the
* socket.
*/
return PCAP_ERROR_PERM_DENIED;
} else {
/*
* Other error.
*/
return PCAP_ERROR;
}
}
/* It seems the kernel supports the new interface. */
handlep->sock_packet = 0;
/*
* Get the interface index of the loopback device.
* If the attempt fails, don't fail, just set the
* "handlep->lo_ifindex" to -1.
*
* XXX - can there be more than one device that loops
* packets back, i.e. devices other than "lo"? If so,
* we'd need to find them all, and have an array of
* indices for them, and check all of them in
* "pcap_read_packet()".
*/
handlep->lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf);
/*
* Default value for offset to align link-layer payload
* on a 4-byte boundary.
*/
handle->offset = 0;
/*
* What kind of frames do we have to deal with? Fall back
* to cooked mode if we have an unknown interface type
* or a type we know doesn't work well in raw mode.
*/
if (!is_any_device) {
/* Assume for now we don't need cooked mode. */
handlep->cooked = 0;
if (handle->opt.rfmon) {
/*
* We were asked to turn on monitor mode.
* Do so before we get the link-layer type,
* because entering monitor mode could change
* the link-layer type.
*/
err = enter_rfmon_mode(handle, sock_fd, device);
if (err < 0) {
/* Hard failure */
close(sock_fd);
return err;
}
if (err == 0) {
/*
* Nothing worked for turning monitor mode
* on.
*/
close(sock_fd);
return PCAP_ERROR_RFMON_NOTSUP;
}
/*
* Either monitor mode has been turned on for
* the device, or we've been given a different
* device to open for monitor mode. If we've
* been given a different device, use it.
*/
if (handlep->mondevice != NULL)
device = handlep->mondevice;
}
arptype = iface_get_arptype(sock_fd, device, handle->errbuf);
if (arptype < 0) {
close(sock_fd);
return arptype;
}
map_arphrd_to_dlt(handle, arptype, device, 1);
if (handle->linktype == -1 ||
handle->linktype == DLT_LINUX_SLL ||
handle->linktype == DLT_LINUX_IRDA ||
handle->linktype == DLT_LINUX_LAPD ||
handle->linktype == DLT_NETLINK ||
(handle->linktype == DLT_EN10MB &&
(strncmp("isdn", device, 4) == 0 ||
strncmp("isdY", device, 4) == 0))) {
/*
* Unknown interface type (-1), or a
* device we explicitly chose to run
* in cooked mode (e.g., PPP devices),
* or an ISDN device (whose link-layer
* type we can only determine by using
* APIs that may be different on different
* kernels) - reopen in cooked mode.
*/
if (close(sock_fd) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"close: %s", pcap_strerror(errno));
return PCAP_ERROR;
}
sock_fd = socket(PF_PACKET, SOCK_DGRAM,
htons(ETH_P_ALL));
if (sock_fd == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
if (errno == EPERM || errno == EACCES) {
/*
* You don't have permission to
* open the socket.
*/
return PCAP_ERROR_PERM_DENIED;
} else {
/*
* Other error.
*/
return PCAP_ERROR;
}
}
handlep->cooked = 1;
/*
* Get rid of any link-layer type list
* we allocated - this only supports cooked
* capture.
*/
if (handle->dlt_list != NULL) {
free(handle->dlt_list);
handle->dlt_list = NULL;
handle->dlt_count = 0;
}
if (handle->linktype == -1) {
/*
* Warn that we're falling back on
* cooked mode; we may want to
* update "map_arphrd_to_dlt()"
* to handle the new type.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"arptype %d not "
"supported by libpcap - "
"falling back to cooked "
"socket",
arptype);
}
/*
* IrDA capture is not a real "cooked" capture,
* it's IrLAP frames, not IP packets. The
* same applies to LAPD capture.
*/
if (handle->linktype != DLT_LINUX_IRDA &&
handle->linktype != DLT_LINUX_LAPD &&
handle->linktype != DLT_NETLINK)
handle->linktype = DLT_LINUX_SLL;
}
handlep->ifindex = iface_get_id(sock_fd, device,
handle->errbuf);
if (handlep->ifindex == -1) {
close(sock_fd);
return PCAP_ERROR;
}
if ((err = iface_bind(sock_fd, handlep->ifindex,
handle->errbuf)) != 1) {
close(sock_fd);
if (err < 0)
return err;
else
return 0; /* try old mechanism */
}
} else {
/*
* The "any" device.
*/
if (handle->opt.rfmon) {
/*
* It doesn't support monitor mode.
*/
close(sock_fd);
return PCAP_ERROR_RFMON_NOTSUP;
}
/*
* It uses cooked mode.
*/
handlep->cooked = 1;
handle->linktype = DLT_LINUX_SLL;
/*
* We're not bound to a device.
* For now, we're using this as an indication
* that we can't transmit; stop doing that only
* if we figure out how to transmit in cooked
* mode.
*/
handlep->ifindex = -1;
}
/*
* Select promiscuous mode on if "promisc" is set.
*
* Do not turn allmulti mode on if we don't select
* promiscuous mode - on some devices (e.g., Orinoco
* wireless interfaces), allmulti mode isn't supported
* and the driver implements it by turning promiscuous
* mode on, and that screws up the operation of the
* card as a normal networking interface, and on no
* other platform I know of does starting a non-
* promiscuous capture affect which multicast packets
* are received by the interface.
*/
/*
* Hmm, how can we set promiscuous mode on all interfaces?
* I am not sure if that is possible at all. For now, we
* silently ignore attempts to turn promiscuous mode on
* for the "any" device (so you don't have to explicitly
* disable it in programs such as tcpdump).
*/
if (!is_any_device && handle->opt.promisc) {
memset(&mr, 0, sizeof(mr));
mr.mr_ifindex = handlep->ifindex;
mr.mr_type = PACKET_MR_PROMISC;
if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
&mr, sizeof(mr)) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"setsockopt: %s", pcap_strerror(errno));
close(sock_fd);
return PCAP_ERROR;
}
}
/* Enable auxillary data if supported and reserve room for
* reconstructing VLAN headers. */
#ifdef HAVE_PACKET_AUXDATA
val = 1;
if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val,
sizeof(val)) == -1 && errno != ENOPROTOOPT) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"setsockopt: %s", pcap_strerror(errno));
close(sock_fd);
return PCAP_ERROR;
}
handle->offset += VLAN_TAG_LEN;
#endif /* HAVE_PACKET_AUXDATA */
/*
* This is a 2.2[.x] or later kernel (we know that
* because we're not using a SOCK_PACKET socket -
* PF_PACKET is supported only in 2.2 and later
* kernels).
*
* We can safely pass "recvfrom()" a byte count
* based on the snapshot length.
*
* If we're in cooked mode, make the snapshot length
* large enough to hold a "cooked mode" header plus
* 1 byte of packet data (so we don't pass a byte
* count of 0 to "recvfrom()").
*/
if (handlep->cooked) {
if (handle->snapshot < SLL_HDR_LEN + 1)
handle->snapshot = SLL_HDR_LEN + 1;
}
handle->bufsize = handle->snapshot;
/*
* Set the offset at which to insert VLAN tags.
*/
switch (handle->linktype) {
case DLT_EN10MB:
handlep->vlan_offset = 2 * ETH_ALEN;
break;
case DLT_LINUX_SLL:
handlep->vlan_offset = 14;
break;
default:
handlep->vlan_offset = -1; /* unknown */
break;
}
#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS)
if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) {
int nsec_tstamps = 1;
if (setsockopt(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, &nsec_tstamps, sizeof(nsec_tstamps)) < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: unable to set SO_TIMESTAMPNS");
close(sock_fd);
return PCAP_ERROR;
}
}
#endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */
/*
* We've succeeded. Save the socket FD in the pcap structure.
*/
handle->fd = sock_fd;
return 1;
#else /* HAVE_PF_PACKET_SOCKETS */
strlcpy(ebuf,
"New packet capturing interface not supported by build "
"environment", PCAP_ERRBUF_SIZE);
return 0;
#endif /* HAVE_PF_PACKET_SOCKETS */
}
#ifdef HAVE_PACKET_RING
/*
* Attempt to activate with memory-mapped access.
*
* On success, returns 1, and sets *status to 0 if there are no warnings
* or to a PCAP_WARNING_ code if there is a warning.
*
* On failure due to lack of support for memory-mapped capture, returns
* 0.
*
* On error, returns -1, and sets *status to the appropriate error code;
* if that is PCAP_ERROR, sets handle->errbuf to the appropriate message.
*/
static int
activate_mmap(pcap_t *handle, int *status)
{
struct pcap_linux *handlep = handle->priv;
int ret;
/*
* Attempt to allocate a buffer to hold the contents of one
* packet, for use by the oneshot callback.
*/
handlep->oneshot_buffer = malloc(handle->snapshot);
if (handlep->oneshot_buffer == NULL) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't allocate oneshot buffer: %s",
pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
if (handle->opt.buffer_size == 0) {
/* by default request 2M for the ring buffer */
handle->opt.buffer_size = 2*1024*1024;
}
ret = prepare_tpacket_socket(handle);
if (ret == -1) {
free(handlep->oneshot_buffer);
*status = PCAP_ERROR;
return ret;
}
ret = create_ring(handle, status);
if (ret == 0) {
/*
* We don't support memory-mapped capture; our caller
* will fall back on reading from the socket.
*/
free(handlep->oneshot_buffer);
return 0;
}
if (ret == -1) {
/*
* Error attempting to enable memory-mapped capture;
* fail. create_ring() has set *status.
*/
free(handlep->oneshot_buffer);
return -1;
}
/*
* Success. *status has been set either to 0 if there are no
* warnings or to a PCAP_WARNING_ value if there is a warning.
*
* Override some defaults and inherit the other fields from
* activate_new.
* handle->offset is used to get the current position into the rx ring.
* handle->cc is used to store the ring size.
*/
switch (handlep->tp_version) {
case TPACKET_V1:
handle->read_op = pcap_read_linux_mmap_v1;
break;
#ifdef HAVE_TPACKET2
case TPACKET_V2:
handle->read_op = pcap_read_linux_mmap_v2;
break;
#endif
#ifdef HAVE_TPACKET3
case TPACKET_V3:
handle->read_op = pcap_read_linux_mmap_v3;
break;
#endif
}
handle->cleanup_op = pcap_cleanup_linux_mmap;
handle->setfilter_op = pcap_setfilter_linux_mmap;
handle->setnonblock_op = pcap_setnonblock_mmap;
handle->getnonblock_op = pcap_getnonblock_mmap;
handle->oneshot_callback = pcap_oneshot_mmap;
handle->selectable_fd = handle->fd;
return 1;
}
#else /* HAVE_PACKET_RING */
static int
activate_mmap(pcap_t *handle _U_, int *status _U_)
{
return 0;
}
#endif /* HAVE_PACKET_RING */
#ifdef HAVE_PACKET_RING
#if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3)
/*
* Attempt to set the socket to the specified version of the memory-mapped
* header.
*
* Return 0 if we succeed; return 1 if we fail because that version isn't
* supported; return -1 on any other error, and set handle->errbuf.
*/
static int
init_tpacket(pcap_t *handle, int version, const char *version_str)
{
struct pcap_linux *handlep = handle->priv;
int val = version;
socklen_t len = sizeof(val);
/* Probe whether kernel supports the specified TPACKET version */
if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) {
if (errno == ENOPROTOOPT || errno == EINVAL)
return 1; /* no */
/* Failed to even find out; this is a fatal error. */
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't get %s header len on packet socket: %s",
version_str,
pcap_strerror(errno));
return -1;
}
handlep->tp_hdrlen = val;
val = version;
if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val,
sizeof(val)) < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't activate %s on packet socket: %s",
version_str,
pcap_strerror(errno));
return -1;
}
handlep->tp_version = version;
/* Reserve space for VLAN tag reconstruction */
val = VLAN_TAG_LEN;
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val,
sizeof(val)) < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't set up reserve on packet socket: %s",
pcap_strerror(errno));
return -1;
}
return 0;
}
#endif /* defined HAVE_TPACKET2 || defined HAVE_TPACKET3 */
/*
* Attempt to set the socket to version 3 of the memory-mapped header and,
* if that fails because version 3 isn't supported, attempt to fall
* back to version 2. If version 2 isn't supported, just leave it at
* version 1.
*
* Return 1 if we succeed or if we fail because neither version 2 nor 3 is
* supported; return -1 on any other error, and set handle->errbuf.
*/
static int
prepare_tpacket_socket(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
#if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3)
int ret;
#endif
handlep->tp_version = TPACKET_V1;
handlep->tp_hdrlen = sizeof(struct tpacket_hdr);
#ifdef HAVE_TPACKET3
/*
* The only mode in which buffering is done on PF_PACKET
* sockets, so that packets might not be delivered
* immediately, is TPACKET_V3 mode.
*
* The buffering cannot be disabled in that mode, so
* if the user has requested immediate mode, we don't
* use TPACKET_V3.
*/
if (handle->opt.immediate)
ret = 1; /* pretend TPACKET_V3 couldn't be set */
else
ret = init_tpacket(handle, TPACKET_V3, "TPACKET_V3");
if (-1 == ret) {
/* Error during setting up TPACKET_V3. */
return -1;
} else if (1 == ret) {
/* TPACKET_V3 not supported - fall back to TPACKET_V2. */
#endif /* HAVE_TPACKET3 */
#ifdef HAVE_TPACKET2
ret = init_tpacket(handle, TPACKET_V2, "TPACKET_V2");
if (-1 == ret) {
/* Error during setting up TPACKET_V2. */
return -1;
}
#endif /* HAVE_TPACKET2 */
#ifdef HAVE_TPACKET3
}
#endif /* HAVE_TPACKET3 */
return 1;
}
/*
* Attempt to set up memory-mapped access.
*
* On success, returns 1, and sets *status to 0 if there are no warnings
* or to a PCAP_WARNING_ code if there is a warning.
*
* On failure due to lack of support for memory-mapped capture, returns
* 0.
*
* On error, returns -1, and sets *status to the appropriate error code;
* if that is PCAP_ERROR, sets handle->errbuf to the appropriate message.
*/
static int
create_ring(pcap_t *handle, int *status)
{
struct pcap_linux *handlep = handle->priv;
unsigned i, j, frames_per_block;
#ifdef HAVE_TPACKET3
/*
* For sockets using TPACKET_V1 or TPACKET_V2, the extra
* stuff at the end of a struct tpacket_req3 will be
* ignored, so this is OK even for those sockets.
*/
struct tpacket_req3 req;
#else
struct tpacket_req req;
#endif
socklen_t len;
unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff;
unsigned int frame_size;
/*
* Start out assuming no warnings or errors.
*/
*status = 0;
switch (handlep->tp_version) {
case TPACKET_V1:
#ifdef HAVE_TPACKET2
case TPACKET_V2:
#endif
/* Note that with large snapshot length (say 64K, which is
* the default for recent versions of tcpdump, the value that
* "-s 0" has given for a long time with tcpdump, and the
* default in Wireshark/TShark/dumpcap), if we use the snapshot
* length to calculate the frame length, only a few frames
* will be available in the ring even with pretty
* large ring size (and a lot of memory will be unused).
*
* Ideally, we should choose a frame length based on the
* minimum of the specified snapshot length and the maximum
* packet size. That's not as easy as it sounds; consider,
* for example, an 802.11 interface in monitor mode, where
* the frame would include a radiotap header, where the
* maximum radiotap header length is device-dependent.
*
* So, for now, we just do this for Ethernet devices, where
* there's no metadata header, and the link-layer header is
* fixed length. We can get the maximum packet size by
* adding 18, the Ethernet header length plus the CRC length
* (just in case we happen to get the CRC in the packet), to
* the MTU of the interface; we fetch the MTU in the hopes
* that it reflects support for jumbo frames. (Even if the
* interface is just being used for passive snooping, the
* driver might set the size of buffers in the receive ring
* based on the MTU, so that the MTU limits the maximum size
* of packets that we can receive.)
*
* We don't do that if segmentation/fragmentation or receive
* offload are enabled, so we don't get rudely surprised by
* "packets" bigger than the MTU. */
frame_size = handle->snapshot;
if (handle->linktype == DLT_EN10MB) {
int mtu;
int offload;
offload = iface_get_offload(handle);
if (offload == -1) {
*status = PCAP_ERROR;
return -1;
}
if (!offload) {
mtu = iface_get_mtu(handle->fd, handle->opt.source,
handle->errbuf);
if (mtu == -1) {
*status = PCAP_ERROR;
return -1;
}
if (frame_size > mtu + 18)
frame_size = mtu + 18;
}
}
/* NOTE: calculus matching those in tpacket_rcv()
* in linux-2.6/net/packet/af_packet.c
*/
len = sizeof(sk_type);
if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type,
&len) < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"getsockopt: %s", pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
#ifdef PACKET_RESERVE
len = sizeof(tp_reserve);
if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE,
&tp_reserve, &len) < 0) {
if (errno != ENOPROTOOPT) {
/*
* ENOPROTOOPT means "kernel doesn't support
* PACKET_RESERVE", in which case we fall back
* as best we can.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"getsockopt: %s", pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
tp_reserve = 0; /* older kernel, reserve not supported */
}
#else
tp_reserve = 0; /* older kernel, reserve not supported */
#endif
maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE;
/* XXX: in the kernel maclen is calculated from
* LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len
* in: packet_snd() in linux-2.6/net/packet/af_packet.c
* then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c
* then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c
* but I see no way to get those sizes in userspace,
* like for instance with an ifreq ioctl();
* the best thing I've found so far is MAX_HEADER in
* the kernel part of linux-2.6/include/linux/netdevice.h
* which goes up to 128+48=176; since pcap-linux.c
* defines a MAX_LINKHEADER_SIZE of 256 which is
* greater than that, let's use it.. maybe is it even
* large enough to directly replace macoff..
*/
tp_hdrlen = TPACKET_ALIGN(handlep->tp_hdrlen) + sizeof(struct sockaddr_ll) ;
netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve;
/* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN
* of netoff, which contradicts
* linux-2.6/Documentation/networking/packet_mmap.txt
* documenting that:
* "- Gap, chosen so that packet data (Start+tp_net)
* aligns to TPACKET_ALIGNMENT=16"
*/
/* NOTE: in linux-2.6/include/linux/skbuff.h:
* "CPUs often take a performance hit
* when accessing unaligned memory locations"
*/
macoff = netoff - maclen;
req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size);
req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size;
break;
#ifdef HAVE_TPACKET3
case TPACKET_V3:
/* The "frames" for this are actually buffers that
* contain multiple variable-sized frames.
*
* We pick a "frame" size of 128K to leave enough
* room for at least one reasonably-sized packet
* in the "frame". */
req.tp_frame_size = MAXIMUM_SNAPLEN;
req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size;
break;
#endif
}
/* compute the minumum block size that will handle this frame.
* The block has to be page size aligned.
* The max block size allowed by the kernel is arch-dependent and
* it's not explicitly checked here. */
req.tp_block_size = getpagesize();
while (req.tp_block_size < req.tp_frame_size)
req.tp_block_size <<= 1;
frames_per_block = req.tp_block_size/req.tp_frame_size;
/*
* PACKET_TIMESTAMP was added after linux/net_tstamp.h was,
* so we check for PACKET_TIMESTAMP. We check for
* linux/net_tstamp.h just in case a system somehow has
* PACKET_TIMESTAMP but not linux/net_tstamp.h; that might
* be unnecessary.
*
* SIOCSHWTSTAMP was introduced in the patch that introduced
* linux/net_tstamp.h, so we don't bother checking whether
* SIOCSHWTSTAMP is defined (if your Linux system has
* linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your
* Linux system is badly broken).
*/
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
/*
* If we were told to do so, ask the kernel and the driver
* to use hardware timestamps.
*
* Hardware timestamps are only supported with mmapped
* captures.
*/
if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER ||
handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) {
struct hwtstamp_config hwconfig;
struct ifreq ifr;
int timesource;
/*
* Ask for hardware time stamps on all packets,
* including transmitted packets.
*/
memset(&hwconfig, 0, sizeof(hwconfig));
hwconfig.tx_type = HWTSTAMP_TX_ON;
hwconfig.rx_filter = HWTSTAMP_FILTER_ALL;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name));
ifr.ifr_data = (void *)&hwconfig;
if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) {
switch (errno) {
case EPERM:
/*
* Treat this as an error, as the
* user should try to run this
* with the appropriate privileges -
* and, if they can't, shouldn't
* try requesting hardware time stamps.
*/
*status = PCAP_ERROR_PERM_DENIED;
return -1;
case EOPNOTSUPP:
/*
* Treat this as a warning, as the
* only way to fix the warning is to
* get an adapter that supports hardware
* time stamps. We'll just fall back
* on the standard host time stamps.
*/
*status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP;
break;
default:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"SIOCSHWTSTAMP failed: %s",
pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
} else {
/*
* Well, that worked. Now specify the type of
* hardware time stamp we want for this
* socket.
*/
if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) {
/*
* Hardware timestamp, synchronized
* with the system clock.
*/
timesource = SOF_TIMESTAMPING_SYS_HARDWARE;
} else {
/*
* PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware
* timestamp, not synchronized with the
* system clock.
*/
timesource = SOF_TIMESTAMPING_RAW_HARDWARE;
}
if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP,
(void *)&timesource, sizeof(timesource))) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't set PACKET_TIMESTAMP: %s",
pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
}
}
#endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */
/* ask the kernel to create the ring */
retry:
req.tp_block_nr = req.tp_frame_nr / frames_per_block;
/* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */
req.tp_frame_nr = req.tp_block_nr * frames_per_block;
#ifdef HAVE_TPACKET3
/* timeout value to retire block - use the configured buffering timeout, or default if <0. */
req.tp_retire_blk_tov = (handlep->timeout>=0)?handlep->timeout:0;
/* private data not used */
req.tp_sizeof_priv = 0;
/* Rx ring - feature request bits - none (rxhash will not be filled) */
req.tp_feature_req_word = 0;
#endif
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
(void *) &req, sizeof(req))) {
if ((errno == ENOMEM) && (req.tp_block_nr > 1)) {
/*
* Memory failure; try to reduce the requested ring
* size.
*
* We used to reduce this by half -- do 5% instead.
* That may result in more iterations and a longer
* startup, but the user will be much happier with
* the resulting buffer size.
*/
if (req.tp_frame_nr < 20)
req.tp_frame_nr -= 1;
else
req.tp_frame_nr -= req.tp_frame_nr/20;
goto retry;
}
if (errno == ENOPROTOOPT) {
/*
* We don't have ring buffer support in this kernel.
*/
return 0;
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't create rx ring on packet socket: %s",
pcap_strerror(errno));
*status = PCAP_ERROR;
return -1;
}
/* memory map the rx ring */
handlep->mmapbuflen = req.tp_block_nr * req.tp_block_size;
handlep->mmapbuf = mmap(0, handlep->mmapbuflen,
PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0);
if (handlep->mmapbuf == MAP_FAILED) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't mmap rx ring: %s", pcap_strerror(errno));
/* clear the allocated ring on error*/
destroy_ring(handle);
*status = PCAP_ERROR;
return -1;
}
/* allocate a ring for each frame header pointer*/
handle->cc = req.tp_frame_nr;
handle->buffer = malloc(handle->cc * sizeof(union thdr *));
if (!handle->buffer) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"can't allocate ring of frame headers: %s",
pcap_strerror(errno));
destroy_ring(handle);
*status = PCAP_ERROR;
return -1;
}
/* fill the header ring with proper frame ptr*/
handle->offset = 0;
for (i=0; i<req.tp_block_nr; ++i) {
void *base = &handlep->mmapbuf[i*req.tp_block_size];
for (j=0; j<frames_per_block; ++j, ++handle->offset) {
RING_GET_FRAME(handle) = base;
base += req.tp_frame_size;
}
}
handle->bufsize = req.tp_frame_size;
handle->offset = 0;
return 1;
}
/* free all ring related resources*/
static void
destroy_ring(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
/* tell the kernel to destroy the ring*/
struct tpacket_req req;
memset(&req, 0, sizeof(req));
/* do not test for setsockopt failure, as we can't recover from any error */
(void)setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
(void *) &req, sizeof(req));
/* if ring is mapped, unmap it*/
if (handlep->mmapbuf) {
/* do not test for mmap failure, as we can't recover from any error */
(void)munmap(handlep->mmapbuf, handlep->mmapbuflen);
handlep->mmapbuf = NULL;
}
}
/*
* Special one-shot callback, used for pcap_next() and pcap_next_ex(),
* for Linux mmapped capture.
*
* The problem is that pcap_next() and pcap_next_ex() expect the packet
* data handed to the callback to be valid after the callback returns,
* but pcap_read_linux_mmap() has to release that packet as soon as
* the callback returns (otherwise, the kernel thinks there's still
* at least one unprocessed packet available in the ring, so a select()
* will immediately return indicating that there's data to process), so,
* in the callback, we have to make a copy of the packet.
*
* Yes, this means that, if the capture is using the ring buffer, using
* pcap_next() or pcap_next_ex() requires more copies than using