source: lib/format_linux_common.c @ 526d9d0

/*
 * This file is part of libtrace
 *
 * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton,
 * New Zealand.
 *
 * Authors: Daniel Lawson
 *          Perry Lorier
 *          Shane Alcock
 *          Richard Sanger
 *
 * All rights reserved.
 *
 * This code has been developed by the University of Waikato WAND
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libtrace is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * libtrace is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with libtrace; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id$
 *
 */

/* This file contains the common functions used by both the ring and int
 * formats.
 *
 * Typically these deal with the socket descriptor or common conversions.
 */

#include "config.h"
#include "libtrace.h"
#include "libtrace_int.h"
#include "format_helper.h"
#include "libtrace_arphrd.h"
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

#ifdef HAVE_INTTYPES_H
#  include <inttypes.h>
#else
# error "Can't find inttypes.h"
#endif

#include "format_linux_common.h"

#ifdef HAVE_NETPACKET_PACKET_H

int linuxcommon_probe_filename(const char *filename)
{
        /* Is this an interface? */
        return (if_nametoindex(filename) != 0);
}

/* Compiles a libtrace BPF filter for use with a linux native socket */
static int linuxnative_configure_bpf(libtrace_t *libtrace,
                libtrace_filter_t *filter) {
#ifdef HAVE_LIBPCAP
        struct ifreq ifr;
        unsigned int arphrd;
        libtrace_dlt_t dlt;
        libtrace_filter_t *f;
        int sock;
        pcap_t *pcap;

        /* Take a copy of the filter object as it was passed in */
        f = (libtrace_filter_t *) malloc(sizeof(libtrace_filter_t));
        memcpy(f, filter, sizeof(libtrace_filter_t));

        /* If we are passed a filter with "flag" set to zero, then we must
         * compile the filterstring before continuing. This involves
         * determining the linktype, passing the filterstring to libpcap to
         * compile, and saving the result for trace_start() to push into the
         * kernel.
         * If flag is set to one, then the filter was probably generated using
         * trace_create_filter_from_bytecode() and so we don't need to do
         * anything (we've just copied it above).
         */
        if (f->flag == 0) {
                sock = socket(PF_INET, SOCK_STREAM, 0);
                memset(&ifr, 0, sizeof(struct ifreq));
                strncpy(ifr.ifr_name, libtrace->uridata, IF_NAMESIZE);
                if (ioctl(sock, SIOCGIFHWADDR, &ifr) != 0) {
                        perror("Can't get HWADDR for interface");
                        return -1;
                }
                close(sock);

                arphrd = ifr.ifr_hwaddr.sa_family;
                dlt = libtrace_to_pcap_dlt(arphrd_type_to_libtrace(arphrd));

                pcap = pcap_open_dead(dlt,
                                FORMAT_DATA->snaplen);

                if (pcap_compile(pcap, &f->filter, f->filterstring, 0, 0) == -1) {
                        /* Filter didn't compile, set flag to 0 so we can
                         * detect this when trace_start() is called and
                         * produce a useful error
                         */
                        f->flag = 0;
                        trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                                      "Failed to compile BPF filter (%s): %s",
                                      f->filterstring, pcap_geterr(pcap));
                } else {
                        /* Set the "flag" to indicate that the filterstring
                         * has been compiled
                         */
                        f->flag = 1;
                }

                pcap_close(pcap);

        }

        if (FORMAT_DATA->filter != NULL)
                free(FORMAT_DATA->filter);

        FORMAT_DATA->filter = f;

        return 0;
#else
        return -1
#endif
}

int linuxcommon_config_input(libtrace_t *libtrace,
                trace_option_t option,
                void *data)
{
        switch(option) {
                case TRACE_OPTION_SNAPLEN:
                        FORMAT_DATA->snaplen=*(int*)data;
                        return 0;
                case TRACE_OPTION_PROMISC:
                        FORMAT_DATA->promisc=*(int*)data;
                        return 0;
                case TRACE_OPTION_FILTER:
                        return linuxnative_configure_bpf(libtrace,
                                        (libtrace_filter_t *) data);
                case TRACE_OPTION_META_FREQ:
                        /* No meta-data for this format */
                        break;
                case TRACE_OPTION_EVENT_REALTIME:
                        /* Live captures are always going to be in trace time */
                        break;
                /* Avoid default: so that future options will cause a warning
                 * here to remind us to implement it, or flag it as
                 * unimplementable
                 */
        }

        /* Don't set an error - trace_config will try to deal with the
         * option and will set an error if it fails */
        return -1;
}

int linuxcommon_init_input(libtrace_t *libtrace)
{
        struct linux_per_stream_t stream_data = ZERO_LINUX_STREAM;

        libtrace->format_data = (struct linux_format_data_t *)
                malloc(sizeof(struct linux_format_data_t));
        assert(libtrace->format_data != NULL);

        FORMAT_DATA->per_stream =
                libtrace_list_init(sizeof(stream_data));
        assert(FORMAT_DATA->per_stream != NULL);

        libtrace_list_push_back(FORMAT_DATA->per_stream, &stream_data);

        FORMAT_DATA->promisc = -1;
        FORMAT_DATA->snaplen = LIBTRACE_PACKET_BUFSIZE;
        FORMAT_DATA->filter = NULL;
        FORMAT_DATA->stats_valid = 0;
        FORMAT_DATA->stats.tp_drops = 0;
        FORMAT_DATA->stats.tp_packets = 0;
        FORMAT_DATA->max_order = MAX_ORDER;
        FORMAT_DATA->fanout_flags = PACKET_FANOUT_LB;
        /* Some examples use pid for the group however that would limit a single
         * application to use only int/ring format, instead using rand */
        FORMAT_DATA->fanout_group = (uint16_t) rand();
        return 0;
}

int linuxcommon_init_output(libtrace_out_t *libtrace)
{
        libtrace->format_data = (struct linux_format_data_out_t*)
                malloc(sizeof(struct linux_format_data_out_t));
        assert(libtrace->format_data != NULL);

        FORMAT_DATA_OUT->fd = -1;
        FORMAT_DATA_OUT->tx_ring = NULL;
        FORMAT_DATA_OUT->txring_offset = 0;
        FORMAT_DATA_OUT->queue = 0;
        FORMAT_DATA_OUT->max_order = MAX_ORDER;
        return 0;
}

/* Close an input stream, this is safe to be called part way through
 * initilisation as a cleanup function assuming streams were set to
 * ZERO_LINUX_STREAM to begin with.
 *
 * This works correctly with both int and ring
 */
void linuxcommon_close_input_stream(libtrace_t *libtrace,
                                    struct linux_per_stream_t *stream) {
        if (stream->fd != -1)
                close(stream->fd);
        stream->fd = -1;
        if (stream->rx_ring != MAP_FAILED)
                munmap(stream->rx_ring,
                       stream->req.tp_block_size *
                       stream->req.tp_block_nr);
        stream->rx_ring = MAP_FAILED;
        FORMAT_DATA->dev_stats.if_name[0] = 0;
}

#define REPEAT_16(x) x x x x x x x x x x x x x x x x
#define xstr(s) str(s)
#define str(s) #s

/* These don't typically reset however an interface does exist to reset them */
static int linuxcommon_get_dev_statisitics(libtrace_t *libtrace, struct linux_dev_stats *stats) {
        FILE *file;
        char line[1024];
        struct linux_dev_stats tmp_stats;

        file = fopen("/proc/net/dev","r");
        if (file == NULL) {
                return -1;
        }

        /* Skip 2 header lines */
        fgets(line, sizeof(line), file);
        fgets(line, sizeof(line), file);

        while (!(feof(file)||ferror(file))) {
                int tot;
                fgets(line, sizeof(line), file);
                tot = sscanf(line, " %"xstr(IF_NAMESIZE)"[^:]:" REPEAT_16(" %"SCNd64),
                             tmp_stats.if_name,
                             &tmp_stats.rx_bytes,
                             &tmp_stats.rx_packets,
                             &tmp_stats.rx_errors,
                             &tmp_stats.rx_drops,
                             &tmp_stats.rx_fifo,
                             &tmp_stats.rx_frame,
                             &tmp_stats.rx_compressed,
                             &tmp_stats.rx_multicast,
                             &tmp_stats.tx_bytes,
                             &tmp_stats.tx_packets,
                             &tmp_stats.tx_errors,
                             &tmp_stats.tx_drops,
                             &tmp_stats.tx_fifo,
                             &tmp_stats.tx_colls,
                             &tmp_stats.tx_carrier,
                             &tmp_stats.tx_compressed);
                if (tot != 17)
                        continue;
                if (strncmp(tmp_stats.if_name, libtrace->uridata, IF_NAMESIZE) == 0) {
                        *stats = tmp_stats;
                        fclose(file);
                        return 0;
                }
        }
        fclose(file);
        return -1;
}

/* Start an input stream
 * - Opens the file descriptor
 * - Sets promiscuous correctly
 * - Sets socket option
 * - Add BPF filter
 *
 * The output is ready for int directly, for ring the conversion to ring still
 * needs to take place.
 */
int linuxcommon_start_input_stream(libtrace_t *libtrace,
                                   struct linux_per_stream_t *stream)
{
        struct sockaddr_ll addr;
        const int one = 1;
        memset(&addr,0,sizeof(addr));
        libtrace_filter_t *filter = FORMAT_DATA->filter;

        /* Create a raw socket for reading packets on */
        stream->fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
        if (stream->fd==-1) {
                trace_set_err(libtrace, errno, "Could not create raw socket");
                return -1;
        }

        /* Bind to the capture interface */
        addr.sll_family = AF_PACKET;
        addr.sll_protocol = htons(ETH_P_ALL);
        if (strlen(libtrace->uridata)) {
                addr.sll_ifindex = if_nametoindex(libtrace->uridata);
                if (addr.sll_ifindex == 0) {
                        linuxcommon_close_input_stream(libtrace, stream);
                        trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                                      "Failed to find interface %s",
                                      libtrace->uridata);
                        return -1;
                }
        } else {
                addr.sll_ifindex = 0;
        }
        if (bind(stream->fd,
                 (struct sockaddr*)&addr,
                 (socklen_t)sizeof(addr))==-1) {
                linuxcommon_close_input_stream(libtrace, stream);
                trace_set_err(libtrace, errno,
                              "Failed to bind to interface %s",
                              libtrace->uridata);
                return -1;
        }

        /* If promisc hasn't been specified, set it to "true" if we're
         * capturing on one interface, or "false" if we're capturing on
         * all interfaces.
         */
        if (FORMAT_DATA->promisc==-1) {
                if (addr.sll_ifindex!=0)
                        FORMAT_DATA->promisc=1;
                else
                        FORMAT_DATA->promisc=0;
        }

        /* Enable promiscuous mode, if requested */
        if (FORMAT_DATA->promisc) {
                struct packet_mreq mreq;
                socklen_t socklen = sizeof(mreq);
                memset(&mreq,0,sizeof(mreq));
                mreq.mr_ifindex = addr.sll_ifindex;
                mreq.mr_type = PACKET_MR_PROMISC;
                if (setsockopt(stream->fd,
                               SOL_PACKET,
                               PACKET_ADD_MEMBERSHIP,
                               &mreq,
                               socklen)==-1) {
                        perror("setsockopt(PROMISC)");
                }
        }

        /* Set the timestamp option on the socket - aim for the most detailed
         * clock resolution possible */
#ifdef SO_TIMESTAMPNS
        if (setsockopt(stream->fd,
                       SOL_SOCKET,
                       SO_TIMESTAMPNS,
                       &one,
                       (socklen_t)sizeof(one))!=-1) {
                FORMAT_DATA->timestamptype = TS_TIMESPEC;
        }
        else
        /* DANGER: This is a dangling else to only do the next setsockopt()
         * if we fail the first! */
#endif
                if (setsockopt(stream->fd,
                               SOL_SOCKET,
                               SO_TIMESTAMP,
                               &one,
                               (socklen_t)sizeof(one))!=-1) {
                        FORMAT_DATA->timestamptype = TS_TIMEVAL;
                }
                else
                        FORMAT_DATA->timestamptype = TS_NONE;

        /* Push BPF filter into the kernel. At this stage we can safely assume
         * that the filterstring has been compiled, or the filter was supplied
         * pre-compiled.
         */
        if (filter != NULL) {
                /* Check if the filter was successfully compiled. If not,
                 * it is probably a bad filter and we should return an error
                 * before the caller tries to read any packets */
                if (filter->flag == 0) {
                        linuxcommon_close_input_stream(libtrace, stream);
                        trace_set_err(libtrace, TRACE_ERR_BAD_FILTER,
                                      "Cannot attach a bad filter to %s",
                                      libtrace->uridata);
                        return -1;
                }

                if (setsockopt(stream->fd,
                               SOL_SOCKET,
                               SO_ATTACH_FILTER,
                               &filter->filter,
                               sizeof(filter->filter)) == -1) {
                        perror("setsockopt(SO_ATTACH_FILTER)");
                }
        }

        /* Consume any buffered packets that were received before the socket
         * was properly setup, including those which missed the filter and
         * bind()ing to an interface.
         *
         * If packet rate is high this could therotically hang forever. 4K
         * should be a large enough limit.
         */
        int count = 0;
        void *buf = malloc((size_t)LIBTRACE_PACKET_BUFSIZE);
        while(count < 4096 &&
                recv(stream->fd,
                   buf,
                   (size_t)LIBTRACE_PACKET_BUFSIZE,
                   MSG_DONTWAIT) != -1) { count++; }
        free(buf);

        /* Mark that the stats are valid and apply an offset */
        FORMAT_DATA->stats_valid = 1;
        /* Offset by number we ate for each stream */
        FORMAT_DATA->stats.tp_packets -= count;


        if (linuxcommon_get_dev_statisitics(libtrace, &FORMAT_DATA->dev_stats) != 0) {
                /* Mark this as bad */
                FORMAT_DATA->dev_stats.if_name[0] = 0;
        }

        return 0;
}

/**
 * Converts a socket, either packet_mmap or standard raw socket into a
 * fanout socket.
 * NOTE: This means we can read from the socket with multiple queues,
 * each must be setup (identically) and then this called upon them
 *
 * @return 0 success, -1 error
 */
inline int linuxcommon_to_packet_fanout(libtrace_t *libtrace,
                                        struct linux_per_stream_t *stream)
{
        int fanout_opt = ((int)FORMAT_DATA->fanout_flags << 16) |
                         (int)FORMAT_DATA->fanout_group;
        if (setsockopt(stream->fd, SOL_PACKET, PACKET_FANOUT,
                        &fanout_opt, sizeof(fanout_opt)) == -1) {
                trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                              "Converting the fd to a socket fanout failed %s",
                              libtrace->uridata);
                return -1;
        }
        return 0;
}

int linuxcommon_pause_input(libtrace_t *libtrace)
{
        size_t i;

        /* Stop and detach each stream */
        for (i = 0; i < libtrace_list_get_size(FORMAT_DATA->per_stream); ++i) {
                struct linux_per_stream_t *stream;
                stream = libtrace_list_get_index(FORMAT_DATA->per_stream, i)->data;
                linuxcommon_close_input_stream(libtrace, stream);
        }

        return 0;
}

int linuxcommon_fin_input(libtrace_t *libtrace)
{
        if (libtrace->format_data) {
                if (FORMAT_DATA->filter != NULL)
                        free(FORMAT_DATA->filter);

                if (FORMAT_DATA->per_stream)
                        libtrace_list_deinit(FORMAT_DATA->per_stream);

                free(libtrace->format_data);
        }

        return 0;
}

int linuxcommon_pregister_thread(libtrace_t *libtrace,
                                 libtrace_thread_t *t,
                                 bool reading) {
        if (reading) {
                /* XXX TODO remove this oneday make sure hasher thread still works */
                struct linux_per_stream_t *stream;
                stream = libtrace_list_get_index(FORMAT_DATA->per_stream,
                                                 t->perpkt_num)->data;
                t->format_data = stream;
                if (!stream) {
                        /* This should never happen and indicates an
                         * internal libtrace bug */
                        trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                                      "Failed to attached thread %d to a stream",
                                      t->perpkt_num);
                        return -1;
                }
        }
        return 0;
}

int linuxcommon_pconfig_input(libtrace_t *libtrace,
                              trace_parallel_option_t option,
                              void *data)
{
        switch(option) {
                case TRACE_OPTION_SET_HASHER:
                        switch (*((enum hasher_types *)data)) {
                                case HASHER_BALANCE:
                                        // Do fanout
                                        FORMAT_DATA->fanout_flags = PACKET_FANOUT_LB;
                                        // Or we could balance to the CPU
                                        return 0;
                                case HASHER_BIDIRECTIONAL:
                                case HASHER_UNIDIRECTIONAL:
                                        FORMAT_DATA->fanout_flags = PACKET_FANOUT_HASH;
                                        return 0;
                                case HASHER_CUSTOM:
                                case HASHER_HARDWARE:
                                        return -1;
                        }
                        break;
                /* Avoid default: so that future options will cause a warning
                 * here to remind us to implement it, or flag it as
                 * unimplementable
                 */
        }

        /* Don't set an error - trace_config will try to deal with the
         * option and will set an error if it fails */
        return -1;
}

/* These counters reset with each read */
static void linuxcommon_update_socket_statistics(libtrace_t *libtrace) {
        struct tpacket_stats stats;
        size_t i;
        socklen_t len = sizeof(stats);

        for (i = 0; i < libtrace_list_get_size(FORMAT_DATA->per_stream); ++i) {
                struct linux_per_stream_t *stream;
                stream = libtrace_list_get_index(FORMAT_DATA->per_stream, i)->data;
                if (stream->fd != -1) {
                        if (getsockopt(stream->fd,
                                   SOL_PACKET,
                                   PACKET_STATISTICS,
                                   &stats,
                                   &len) == 0) {
                                if (FORMAT_DATA->stats_valid==0) {
                                        FORMAT_DATA->stats.tp_drops = stats.tp_drops;
                                        FORMAT_DATA->stats.tp_packets = stats.tp_packets;
                                        FORMAT_DATA->stats_valid = 1;
                                } else {
                                        FORMAT_DATA->stats.tp_drops += stats.tp_drops;
                                        FORMAT_DATA->stats.tp_packets += stats.tp_packets;
                                }
                        } else {
                                perror("getsockopt PACKET_STATISTICS failed");
                        }
                }
        }
}

#define DEV_DIFF(x) (dev_stats.x - FORMAT_DATA->dev_stats.x)
/* Note these statistics come from two different sources, the socket itself and
 * the linux device. As such this means it is highly likely that their is some
 * margin of error in the returned statisitics, we perform basic sanitising so
 * that these are not too noticable.
 */
void linuxcommon_get_statistics(libtrace_t *libtrace, libtrace_stat_t *stat) {
        struct linux_dev_stats dev_stats;
        if (libtrace->format_data == NULL)
                return;
        /* Do we need to consider the case after the trace is closed? */
        if (FORMAT_DATA_FIRST->fd == -1) {
                /* This is probably a 'dead' trace so obviously we can't query
                 * the socket for capture counts, can we? */
                return;
        }

        dev_stats.if_name[0] = 0; /* This will be set if we retrive valid stats */
        /* Do we have starting stats to compare to? */
        if (FORMAT_DATA->dev_stats.if_name[0] != 0) {
                linuxcommon_get_dev_statisitics(libtrace, &dev_stats);
        }
        linuxcommon_update_socket_statistics(libtrace);

        /* filtered count == dev received - socket received */
        if (FORMAT_DATA->filter != NULL &&
            FORMAT_DATA->stats_valid &&
            dev_stats.if_name[0]) {
                uint64_t filtered = DEV_DIFF(rx_packets) -
                                    FORMAT_DATA->stats.tp_packets;
                /* Check the value is sane, due to timing it could be below 0 */
                if (filtered < UINT64_MAX - 100000) {
                        stat->filtered += filtered;
                }
        }

        /* dropped count == socket dropped + dev dropped */
        if (FORMAT_DATA->stats_valid) {
                stat->dropped_valid = 1;
                stat->dropped = FORMAT_DATA->stats.tp_drops;
                if (dev_stats.if_name[0]) {
                        stat->dropped += DEV_DIFF(rx_drops);
                }
        }

        /* received count - All good packets even those dropped or filtered */
        if (dev_stats.if_name[0]) {
                stat->received_valid = 1;
                stat->received = DEV_DIFF(rx_packets) + DEV_DIFF(rx_drops);
        }

        /* captured count - received and but not dropped */
        if (dev_stats.if_name[0] && FORMAT_DATA->stats_valid) {
                stat->captured_valid = 1;
                stat->captured = DEV_DIFF(rx_packets) - FORMAT_DATA->stats.tp_drops;
        }

        /* errors */
        if (dev_stats.if_name[0]) {
                stat->errors_valid = 1;
                stat->errors = DEV_DIFF(rx_errors);
        }

}

int linuxcommon_get_fd(const libtrace_t *libtrace) {
        if (libtrace->format_data == NULL)
                return -1;
        return FORMAT_DATA_FIRST->fd;
}

int linuxcommon_pstart_input(libtrace_t *libtrace,
                             int (*start_stream)(libtrace_t *, struct linux_per_stream_t*)) {
        int i = 0;
        int tot = libtrace->perpkt_thread_count;
        int iserror = 0;
        struct linux_per_stream_t empty_stream = ZERO_LINUX_STREAM;

        printf("Calling native pstart packet\n");
        for (i = 0; i < tot; ++i)
        {
                struct linux_per_stream_t *stream;
                /* Add storage for another stream */
                if (libtrace_list_get_size(FORMAT_DATA->per_stream) <= (size_t) i)
                        libtrace_list_push_back(FORMAT_DATA->per_stream, &empty_stream);

                stream = libtrace_list_get_index(FORMAT_DATA->per_stream, i)->data;
                if (start_stream(libtrace, stream) != 0) {
                        iserror = 1;
                        break;
                }
                if (linuxcommon_to_packet_fanout(libtrace, stream) != 0)
                {
                        iserror = 1;
                        close(stream->fd);
                        stream->fd = -1;
                        break;
                }
        }

        if (iserror) {
                /* Free those that succeeded */
                for (i = i - 1; i >= 0; i--) {
                        struct linux_per_stream_t *stream;
                        stream = libtrace_list_get_index(FORMAT_DATA->per_stream, i)->data;
                        linuxcommon_close_input_stream(libtrace, stream);
                }
                libtrace_list_deinit(FORMAT_DATA->per_stream);
                free(libtrace->format_data);
                libtrace->format_data = NULL;
                return -1;
        }

        return 0;
}

#else /* HAVE_NETPACKET_PACKET_H */

/* No NETPACKET - So this format is not live */
void linuxcommon_get_statistics(libtrace_t *libtrace UNUSED,
                                libtrace_stat_t *stat UNUSED) {
        return;
}

#endif /* HAVE_NETPACKET_PACKET_H */


inline libtrace_direction_t linuxcommon_get_direction(uint8_t pkttype)
{
        switch (pkttype) {
                case PACKET_OUTGOING:
                case PACKET_LOOPBACK:
                        return TRACE_DIR_OUTGOING;
                case PACKET_OTHERHOST:
                        return TRACE_DIR_OTHER;
                default:
                        return TRACE_DIR_INCOMING;
        }
}

inline libtrace_direction_t
linuxcommon_set_direction(struct sockaddr_ll * skadr,
                          libtrace_direction_t direction)
{
        switch (direction) {
                case TRACE_DIR_OUTGOING:
                        skadr->sll_pkttype = PACKET_OUTGOING;
                        return TRACE_DIR_OUTGOING;
                case TRACE_DIR_INCOMING:
                        skadr->sll_pkttype = PACKET_HOST;
                        return TRACE_DIR_INCOMING;
                case TRACE_DIR_OTHER:
                        skadr->sll_pkttype = PACKET_OTHERHOST;
                        return TRACE_DIR_OTHER;
                default:
                        return -1;
        }
}

inline libtrace_linktype_t linuxcommon_get_link_type(uint16_t linktype)
{
        /* Convert the ARPHRD type into an appropriate libtrace link type */
        switch (linktype) {
                case LIBTRACE_ARPHRD_ETHER:
                case LIBTRACE_ARPHRD_LOOPBACK:
                        return TRACE_TYPE_ETH;
                case LIBTRACE_ARPHRD_PPP:
                        return TRACE_TYPE_NONE;
                case LIBTRACE_ARPHRD_IEEE80211_RADIOTAP:
                        return TRACE_TYPE_80211_RADIO;
                case LIBTRACE_ARPHRD_IEEE80211:
                        return TRACE_TYPE_80211;
                case LIBTRACE_ARPHRD_SIT:
                case LIBTRACE_ARPHRD_NONE:
                        return TRACE_TYPE_NONE;
                default: /* shrug, beyond me! */
                        printf("unknown Linux ARPHRD type 0x%04x\n",linktype);
                        return (libtrace_linktype_t)~0U;
        }
}