source: lib/format_dag25.c

/*
 *
 * Copyright (c) 2007-2016 The University of Waikato, Hamilton, New Zealand.
 * All rights reserved.
 *
 * This file is part of libtrace.
 *
 * 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 Lesser General Public License as published by
 * the Free Software Foundation; either version 3 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */
#define _GNU_SOURCE

#include "config.h"
#include "common.h"
#include "libtrace.h"
#include "libtrace_int.h"
#include "format_helper.h"
#include "format_erf.h"

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>

#include <sys/mman.h>
/* XXX: Windows doesn't have pthreads, but this code doesn't compile under
 * Windows anyway so we'll worry about this more later :] */
#include <pthread.h>


#ifdef HAVE_DAG_CONFIG_API_H
#include <dag_config_api.h>
#endif

#ifdef WIN32
#  include <io.h>
#  include <share.h>
#  define PATH_MAX _MAX_PATH
#  define snprintf sprintf_s
#else
#  include <netdb.h>
#  ifndef PATH_MAX
#       define PATH_MAX 4096
#  endif
#  include <sys/ioctl.h>
#endif

/* This format deals with DAG cards that are using drivers from the 2.5 version
 * onwards, including 3.X.
 *
 * DAG is a LIVE capture format.
 *
 * This format does support writing, provided the DAG card that you are using
 * has transmit (Tx) support. Additionally, packets read using this format
 * are in the ERF format, so can easily be written as ERF traces without
 * losing any data.
 */

#define DATA(x) ((struct dag_format_data_t *)x->format_data)
#define DATA_OUT(x) ((struct dag_format_data_out_t *)x->format_data)
#define STREAM_DATA(x) ((struct dag_per_stream_t *)x->data)

#define FORMAT_DATA DATA(libtrace)
#define FORMAT_DATA_OUT DATA_OUT(libtrace)

#define DUCK FORMAT_DATA->duck

#define FORMAT_DATA_HEAD FORMAT_DATA->per_stream->head
#define FORMAT_DATA_FIRST ((struct dag_per_stream_t *)FORMAT_DATA_HEAD->data)

static struct libtrace_format_t dag;

/* A DAG device - a DAG device can support multiple streams (and therefore
 * multiple input traces) so each trace needs to refer to a device */
struct dag_dev_t {
        char * dev_name;                /* Device name */
        int fd;                         /* File descriptor */
        uint16_t ref_count;             /* Number of input / output traces
                                           that are using this device */
        struct dag_dev_t *prev;         /* Pointer to the previous device in
                                           the device list */
        struct dag_dev_t *next;         /* Pointer to the next device in the
                                           device list */
};

/* "Global" data that is stored for each DAG output trace */
struct dag_format_data_out_t {
        /* The DAG device being used for writing */
        struct dag_dev_t *device;
        /* The DAG stream that is being written on */
        unsigned int dagstream;
        /* Boolean flag indicating whether the stream is currently attached */
        int stream_attached;
        /* The amount of data waiting to be transmitted, in bytes */
        uint64_t waiting;
        /* A buffer to hold the data to be transmittted */
        uint8_t *txbuffer;
};

/* Data that is stored against each input stream */
struct dag_per_stream_t {
        /* DAG stream number */
        uint16_t dagstream;
        /* Pointer to the last unread byte in the DAG memory */
        uint8_t *top;
        /* Pointer to the first unread byte in the DAG memory */
        uint8_t *bottom;
        /* Amount of data processed from the bottom pointer */
        uint32_t processed;
        /* Number of packets seen by the stream */
        uint64_t pkt_count;
        /* Drop count for this particular stream */
        uint64_t drops;
        /* Boolean values to indicate if a particular interface has been seen
         * or not. This is limited to four interfaces, which is enough to
         * support all current DAG cards */
        uint8_t seeninterface[4];
};

/* "Global" data that is stored for each DAG input trace */
struct dag_format_data_t {
        /* DAG device */
        struct dag_dev_t *device;
        /* Boolean flag indicating whether the trace is currently attached */
        int stream_attached;
        /* Data stored against each DAG input stream */
        libtrace_list_t *per_stream;

        /* Data required for regular DUCK reporting.
         * We put this on a new cache line otherwise we have a lot of false
         * sharing caused by updating the last_pkt.
         * This should only ever be accessed by the first thread stream,
         * that includes both read and write operations.
         */
        struct {
                /* Timestamp of the last DUCK report */
                uint32_t last_duck;
                /* The number of seconds between each DUCK report */
                uint32_t duck_freq;
                /* Timestamp of the last packet read from the DAG card */
                uint32_t last_pkt;
                /* Dummy trace to ensure DUCK packets are dealt with using the
                 * DUCK format functions */
                libtrace_t *dummy_duck;
        } duck ALIGN_STRUCT(CACHE_LINE_SIZE);
};

/* To be thread-safe, we're going to need a mutex for operating on the list
 * of DAG devices */
pthread_mutex_t open_dag_mutex;

/* The list of DAG devices that have been opened by libtrace.
 *
 * We can only open each DAG device once, but we might want to read from
 * multiple streams. Therefore, we need to maintain a list of devices that we
 * have opened (with ref counts!) so that we don't try to open a device too
 * many times or close a device that we're still using */
struct dag_dev_t *open_dags = NULL;

static bool dag_can_write(libtrace_packet_t *packet) {
        /* Get the linktype */
        libtrace_linktype_t ltype = trace_get_link_type(packet);

        if (ltype == TRACE_TYPE_CONTENT_INVALID) {
                return false;
        }

        /* TODO erf meta should definitely be writable, pcapng meta
         * could probably be converted into erf meta */
        if (ltype == TRACE_TYPE_ERF_META
                        || ltype == TRACE_TYPE_NONDATA
                        || ltype == TRACE_TYPE_PCAPNG_META) {
                return false;
        }

        return true;
}

/* Returns the amount of padding between the ERF header and the start of the
 * captured packet data */
static int dag_get_padding(const libtrace_packet_t *packet)
{
        /* ERF Ethernet records have a 2 byte padding before the packet itself
         * so that the IP header is aligned on a 32 bit boundary.
         */
        if (packet->trace->format->type==TRACE_FORMAT_ERF) {
                dag_record_t *erfptr = (dag_record_t *)packet->header;
                switch(erfptr->type) {
                        case TYPE_ETH:
                        case TYPE_COLOR_ETH:
                        case TYPE_DSM_COLOR_ETH:
                        case TYPE_COLOR_HASH_ETH:
                                return 2;
                        default:                return 0;
                }
        }
        else {
                switch(trace_get_link_type(packet)) {
                        case TRACE_TYPE_ETH:    return 2;
                        default:                return 0;
                }
        }
}

/* Attempts to determine if the given filename refers to a DAG device */
static int dag_probe_filename(const char *filename)
{
        struct stat statbuf;
        /* Can we stat the file? */
        if (stat(filename, &statbuf) != 0) {
                return 0;
        }
        /* Is it a character device? */
        if (!S_ISCHR(statbuf.st_mode)) {
                return 0;
        }
        /* Yeah, it's probably us. */
        return 1;
}

/* Initialises the DAG output data structure */
static void dag_init_format_out_data(libtrace_out_t *libtrace)
{
        libtrace->format_data = (struct dag_format_data_out_t *)
                malloc(sizeof(struct dag_format_data_out_t));
        // no DUCK on output
        FORMAT_DATA_OUT->stream_attached = 0;
        FORMAT_DATA_OUT->device = NULL;
        FORMAT_DATA_OUT->dagstream = 0;
        FORMAT_DATA_OUT->waiting = 0;

}

/* Initialises the DAG input data structure */
static void dag_init_format_data(libtrace_t *libtrace)
{
        struct dag_per_stream_t stream_data;

        libtrace->format_data = (struct dag_format_data_t *)
                malloc(sizeof(struct dag_format_data_t));
        DUCK.last_duck = 0;
        DUCK.duck_freq = 0;
        DUCK.last_pkt = 0;
        DUCK.dummy_duck = NULL;

        FORMAT_DATA->per_stream =
                libtrace_list_init(sizeof(stream_data));
        if (FORMAT_DATA->per_stream == NULL) {
                trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                        "Unable to create list for stream in dag_init_format_data()");
                return;
        }

        /* We'll start with just one instance of stream_data, and we'll
         * add more later if we need them */
        memset(&stream_data, 0, sizeof(stream_data));
        libtrace_list_push_back(FORMAT_DATA->per_stream, &stream_data);
}

/* Determines if there is already an entry for the given DAG device in the
 * device list and increments the reference count for that device, if found.
 *
 * NOTE: This function assumes the open_dag_mutex is held by the caller */
static struct dag_dev_t *dag_find_open_device(char *dev_name)
{
        struct dag_dev_t *dag_dev;

        dag_dev = open_dags;

        /* XXX: Not exactly zippy, but how often are we going to be dealing
         * with multiple dag cards? */
        while (dag_dev != NULL) {
                if (strcmp(dag_dev->dev_name, dev_name) == 0) {
                        dag_dev->ref_count ++;
                        return dag_dev;
                }
                dag_dev = dag_dev->next;
        }
        return NULL;
}

/* Closes a DAG device and removes it from the device list.
 *
 * Attempting to close a DAG device that has a non-zero reference count will
 * cause an assertion failure!
 *
 * NOTE: This function assumes the open_dag_mutex is held by the caller */
static void dag_close_device(struct dag_dev_t *dev)
{
        /* Need to remove from the device list */
        if (dev->ref_count != 0) {
                fprintf(stderr, "Cannot close DAG device with non zero reference in dag_close_device()\n");
                return;
        }

        if (dev->prev == NULL) {
                open_dags = dev->next;
                if (dev->next)
                        dev->next->prev = NULL;
        } else {
                dev->prev->next = dev->next;
                if (dev->next)
                        dev->next->prev = dev->prev;
        }

        dag_close(dev->fd);
        free(dev);
}


/* Opens a new DAG device for writing and adds it to the DAG device list
 *
 * NOTE: this function should only be called when opening a DAG device for
 * writing - there is little practical difference between this and the
 * function below that covers the reading case, but we need the output trace
 * object to report errors properly so the two functions take slightly
 * different arguments. This is really lame and there should be a much better
 * way of doing this.
 *
 * NOTE: This function assumes the open_dag_mutex is held by the caller
 */
static struct dag_dev_t *dag_open_output_device(libtrace_out_t *libtrace,
                                                char *dev_name)
{
        struct stat buf;
        int fd;
        struct dag_dev_t *new_dev;

        /* Make sure the device exists */
        if (stat(dev_name, &buf) == -1) {
                trace_set_err_out(libtrace,errno,"stat(%s)",dev_name);
                return NULL;
        }

        /* Make sure it is the appropriate type of device */
        if (S_ISCHR(buf.st_mode)) {
                /* Try opening the DAG device */
                if((fd = dag_open(dev_name)) < 0) {
                        trace_set_err_out(libtrace,errno,"Cannot open DAG %s",
                                        dev_name);
                        return NULL;
                }
        } else {
                trace_set_err_out(libtrace,errno,"Not a valid dag device: %s",
                                dev_name);
                return NULL;
        }

        /* Add the device to our device list - it is just a doubly linked
         * list with no inherent ordering; just tack the new one on the front
         */
        new_dev = (struct dag_dev_t *)malloc(sizeof(struct dag_dev_t));
        new_dev->fd = fd;
        new_dev->dev_name = dev_name;
        new_dev->ref_count = 1;

        new_dev->prev = NULL;
        new_dev->next = open_dags;
        if (open_dags)
                open_dags->prev = new_dev;

        open_dags = new_dev;

        return new_dev;
}

/* Opens a new DAG device for reading and adds it to the DAG device list
 *
 * NOTE: this function should only be called when opening a DAG device for
 * reading - there is little practical difference between this and the
 * function above that covers the writing case, but we need the input trace
 * object to report errors properly so the two functions take slightly
 * different arguments. This is really lame and there should be a much better
 * way of doing this.
 *
 * NOTE: This function assumes the open_dag_mutex is held by the caller */
static struct dag_dev_t *dag_open_device(libtrace_t *libtrace, char *dev_name) {
        struct stat buf;
        int fd;
        struct dag_dev_t *new_dev;

        /* Make sure the device exists */
        if (stat(dev_name, &buf) == -1) {
                trace_set_err(libtrace,errno,"stat(%s)",dev_name);
                return NULL;
        }

        /* Make sure it is the appropriate type of device */
        if (S_ISCHR(buf.st_mode)) {
                /* Try opening the DAG device */
                if((fd = dag_open(dev_name)) < 0) {
                        trace_set_err(libtrace,errno,"Cannot open DAG %s",
                                      dev_name);
                        return NULL;
                }
        } else {
                trace_set_err(libtrace,errno,"Not a valid dag device: %s",
                              dev_name);
                return NULL;
        }

        /* Add the device to our device list - it is just a doubly linked
         * list with no inherent ordering; just tack the new one on the front
         */
        new_dev = (struct dag_dev_t *)malloc(sizeof(struct dag_dev_t));
        new_dev->fd = fd;
        new_dev->dev_name = dev_name;
        new_dev->ref_count = 1;

        new_dev->prev = NULL;
        new_dev->next = open_dags;
        if (open_dags)
                open_dags->prev = new_dev;

        open_dags = new_dev;

        return new_dev;
}

/* Creates and initialises a DAG output trace */
static int dag_init_output(libtrace_out_t *libtrace)
{
        /* Upon successful creation, the device name is stored against the
         * device and free when it is free()d */
        char *dag_dev_name = NULL;
        char *scan = NULL;
        struct dag_dev_t *dag_device = NULL;
        int stream = 1;

        /* XXX I don't know if this is important or not, but this function
         * isn't present in all of the driver releases that this code is
         * supposed to support! */
        /*
        unsigned long wake_time;
        dagutil_sleep_get_wake_time(&wake_time,0);
        */

        dag_init_format_out_data(libtrace);
        /* Grab the mutex while we're likely to be messing with the device
         * list */
        pthread_mutex_lock(&open_dag_mutex);

        /* Specific streams are signified using a comma in the libtrace URI,
         * e.g. dag:/dev/dag0,1 refers to stream 1 on the dag0 device.
         *
         * If no stream is specified, we will write using stream 1 */
        if ((scan = strchr(libtrace->uridata,',')) == NULL) {
                dag_dev_name = strdup(libtrace->uridata);
        } else {
                dag_dev_name = (char *)strndup(libtrace->uridata,
                                (size_t)(scan - libtrace->uridata));
                stream = atoi(++scan);
        }
        FORMAT_DATA_OUT->dagstream = stream;

        /* See if our DAG device is already open */
        dag_device = dag_find_open_device(dag_dev_name);

        if (dag_device == NULL) {
                /* Device not yet opened - open it ourselves */
                dag_device = dag_open_output_device(libtrace, dag_dev_name);
        } else {
                /* Otherwise, just use the existing one */
                free(dag_dev_name);
                dag_dev_name = NULL;
        }

        /* Make sure we have successfully opened a DAG device */
        if (dag_device == NULL) {
                if (dag_dev_name) {
                        free(dag_dev_name);
                }
                pthread_mutex_unlock(&open_dag_mutex);
                return -1;
        }

        FORMAT_DATA_OUT->device = dag_device;
        pthread_mutex_unlock(&open_dag_mutex);
        return 0;
}

/* Creates and initialises a DAG input trace */
static int dag_init_input(libtrace_t *libtrace) {
        /* Upon successful creation, the device name is stored against the
         * device and free when it is free()d */
        char *dag_dev_name = NULL;
        char *scan = NULL;
        int stream = 0;
        struct dag_dev_t *dag_device = NULL;

        dag_init_format_data(libtrace);
        /* Grab the mutex while we're likely to be messing with the device
         * list */
        pthread_mutex_lock(&open_dag_mutex);


        /* DAG cards support multiple streams. In a single threaded capture,
         * these are specified using a comma in the libtrace URI,
         * e.g. dag:/dev/dag0,2 refers to stream 2 on the dag0 device.
         *
         * If no stream is specified, we will read from stream 0 with
         * one thread
         */
        if ((scan = strchr(libtrace->uridata,',')) == NULL) {
                dag_dev_name = strdup(libtrace->uridata);
        } else {
                dag_dev_name = (char *)strndup(libtrace->uridata,
                                (size_t)(scan - libtrace->uridata));
                stream = atoi(++scan);
        }

        FORMAT_DATA_FIRST->dagstream = stream;

        /* See if our DAG device is already open */
        dag_device = dag_find_open_device(dag_dev_name);

        if (dag_device == NULL) {
                /* Device not yet opened - open it ourselves */
                dag_device = dag_open_device(libtrace, dag_dev_name);
        } else {
                /* Otherwise, just use the existing one */
                free(dag_dev_name);
                dag_dev_name = NULL;
        }

        /* Make sure we have successfully opened a DAG device */
        if (dag_device == NULL) {
                if (dag_dev_name)
                        free(dag_dev_name);
                dag_dev_name = NULL;
                pthread_mutex_unlock(&open_dag_mutex);
                trace_set_err(libtrace, TRACE_ERR_INIT_FAILED, "Unable to open DAG device %s", dag_dev_name);
                return -1;
        }

        FORMAT_DATA->device = dag_device;

        /* See Config_Status_API_Programming_Guide.pdf from the Endace
           Dag Documentation */
        /* Check kBooleanAttributeActive is true -- no point capturing
         * on an interface that's disabled
         *
         * The symptom of the port being disabled is that libtrace
         * will appear to hang. */
        /* Check kBooleanAttributeFault is false */
        /* Check kBooleanAttributeLocalFault is false */
        /* Check kBooleanAttributeLock is true ? */
        /* Check kBooleanAttributePeerLink ? */

        /* Set kBooleanAttributePromisc/kBooleanPromiscuousMode based
           on libtrace promisc attribute?*/
        /* Set kUint32AttributeSnapLength to the snaplength */

        pthread_mutex_unlock(&open_dag_mutex);
        return 0;
}

#ifdef HAVE_DAG_CONFIG_API_H
static int dag_csapi_set_snaplen(libtrace_t *libtrace, int slen) {
        dag_card_ref_t card_ref = NULL;
        dag_component_t root = NULL;
        attr_uuid_t uuid = 0;

        if (slen < 0)
                slen = 0; 

        card_ref = dag_config_init(FORMAT_DATA->device->dev_name);
        root = dag_config_get_root_component(card_ref);
        
        uuid = dag_component_get_config_attribute_uuid(root, kBooleanAttributeVarlen);
        dag_config_set_boolean_attribute(card_ref, uuid, true);

        uuid = dag_component_get_config_attribute_uuid(root, kUint32AttributeSnaplength);
        dag_config_set_uint32_attribute(card_ref, uuid, (uint32_t)slen);

        return 0;
        

} 
#endif /* HAVE_DAG_CONFIG_API_H */

/* Configures a DAG input trace */
static int dag_config_input(libtrace_t *libtrace, trace_option_t option,
                            void *data)
{
        switch(option) {
        case TRACE_OPTION_META_FREQ:
                /* This option is used to specify the frequency of DUCK
                 * updates */
                DUCK.duck_freq = *(int *)data;
                return 0;
        case TRACE_OPTION_SNAPLEN:
#ifdef HAVE_DAG_CONFIG_API_H
                return dag_csapi_set_snaplen(libtrace, *(int *)data);
#else
                /* Tell the card our new snap length */
        {
                char conf_str[4096];
                snprintf(conf_str, 4096, "varlen slen=%i", *(int *)data);
                if (dag_configure(FORMAT_DATA->device->fd,
                                  conf_str) != 0) {
                        trace_set_err(libtrace, errno, "Failed to configure "
                                      "snaplen on DAG card: %s",
                                      libtrace->uridata);
                        return -1;
                }
        }
#endif /* HAVE_DAG_CONFIG_API_H */

                return 0;
        case TRACE_OPTION_PROMISC:
                /* DAG already operates in a promisc fashion */
                return -1;
        case TRACE_OPTION_FILTER:
                /* We don't yet support pushing filters into DAG
                 * cards */
                return -1;
        case TRACE_OPTION_EVENT_REALTIME:
        case TRACE_OPTION_REPLAY_SPEEDUP:
                /* Live capture is always going to be realtime */
                return -1;
        case TRACE_OPTION_HASHER:
                /* Lets just say we did this, it's currently still up to
                 * the user to configure this correctly. */
                return 0;
        case TRACE_OPTION_CONSTANT_ERF_FRAMING:
                return -1;
        }
        return -1;
}

/* Starts a DAG output trace */
static int dag_start_output(libtrace_out_t *libtrace)
{
        struct timeval zero, nopoll;

        zero.tv_sec = 0;
        zero.tv_usec = 0;
        nopoll = zero;

        /* Attach and start the DAG stream */
        if (dag_attach_stream64(FORMAT_DATA_OUT->device->fd,
                        FORMAT_DATA_OUT->dagstream, 0, 4 * 1024 * 1024) < 0) {
                trace_set_err_out(libtrace, errno, "Cannot attach DAG stream");
                return -1;
        }

        if (dag_start_stream(FORMAT_DATA_OUT->device->fd,
                        FORMAT_DATA_OUT->dagstream) < 0) {
                trace_set_err_out(libtrace, errno, "Cannot start DAG stream");
                return -1;
        }
        FORMAT_DATA_OUT->stream_attached = 1;

        /* We don't want the dag card to do any sleeping */
        dag_set_stream_poll64(FORMAT_DATA_OUT->device->fd,
                        FORMAT_DATA_OUT->dagstream, 0, &zero,
                        &nopoll);

        return 0;
}

static int dag_start_input_stream(libtrace_t *libtrace,
                                  struct dag_per_stream_t * stream) {
        struct timeval zero, nopoll;
        uint8_t *top, *bottom, *starttop;
        top = bottom = NULL;

        zero.tv_sec = 0;
        zero.tv_usec = 10000;
        nopoll = zero;

        /* Attach and start the DAG stream */
        if (dag_attach_stream64(FORMAT_DATA->device->fd,
                              stream->dagstream, 0, 0) < 0) {
                trace_set_err(libtrace, errno, "Cannot attach DAG stream #%u",
                              stream->dagstream);
                return -1;
        }

        if (dag_start_stream(FORMAT_DATA->device->fd,
                             stream->dagstream) < 0) {
                trace_set_err(libtrace, errno, "Cannot start DAG stream #%u",
                              stream->dagstream);
                return -1;
        }
        FORMAT_DATA->stream_attached = 1;

        /* We don't want the dag card to do any sleeping */
        if (dag_set_stream_poll64(FORMAT_DATA->device->fd,
                            stream->dagstream, 0, &zero,
                            &nopoll) < 0) {
                trace_set_err(libtrace, errno,
                              "dag_set_stream_poll failed!");
                return -1;
        }

        starttop = dag_advance_stream(FORMAT_DATA->device->fd,
                                      stream->dagstream,
                                      &bottom);

        /* Should probably flush the memory hole now */
        top = starttop;
        while (starttop - bottom > 0) {
                bottom += (starttop - bottom);
                top = dag_advance_stream(FORMAT_DATA->device->fd,
                                         stream->dagstream,
                                         &bottom);
        }
        stream->top = top;
        stream->bottom = bottom;
        stream->processed = 0;
        stream->drops = 0;

        return 0;

}

/* Starts a DAG input trace */
static int dag_start_input(libtrace_t *libtrace)
{
        return dag_start_input_stream(libtrace, FORMAT_DATA_FIRST);
}

static int dag_pstart_input(libtrace_t *libtrace)
{
        char *scan, *tok;
        uint16_t stream_count = 0, max_streams;
        int iserror = 0;
        struct dag_per_stream_t stream_data;

        /* Check we aren't trying to create more threads than the DAG card can
         * handle */
        max_streams = dag_rx_get_stream_count(FORMAT_DATA->device->fd);
        if (libtrace->perpkt_thread_count > max_streams) {
                fprintf(stderr,
                              "WARNING: DAG has only %u streams available, "
                              "capping total number of threads at this value.",
                              max_streams);
                libtrace->perpkt_thread_count = max_streams;
        }

        /* Get the stream names from the uri */
        if ((scan = strchr(libtrace->uridata, ',')) == NULL) {
                trace_set_err(libtrace, TRACE_ERR_BAD_FORMAT,
                              "Format uri doesn't specify the DAG streams");
                iserror = 1;
                goto cleanup;
        }

        scan++;

        tok = strtok(scan, ",");
        while (tok != NULL) {
                /* Ensure we haven't specified too many streams */
                if (stream_count >= libtrace->perpkt_thread_count) {
                        fprintf(stderr,
                                      "WARNING: Format uri specifies too many "
                                      "streams. Maximum is %u, so only using "
                                      "the first %u from the uri.",
                                      libtrace->perpkt_thread_count, 
                                      libtrace->perpkt_thread_count);
                        break;
                }

                /* Save the stream details */
                if (stream_count == 0) {
                        /* Special case where we update the existing stream
                         * data structure */
                        FORMAT_DATA_FIRST->dagstream = (uint16_t)atoi(tok);
                } else {
                        memset(&stream_data, 0, sizeof(stream_data));
                        stream_data.dagstream = (uint16_t)atoi(tok);
                        libtrace_list_push_back(FORMAT_DATA->per_stream,
                                                &stream_data);
                }

                stream_count++;
                tok = strtok(NULL, ",");
        }

        if (stream_count < libtrace->perpkt_thread_count) {
                libtrace->perpkt_thread_count = stream_count;
        }
        
        FORMAT_DATA->stream_attached = 1;

 cleanup:
        if (iserror) {
                return -1;
        } else {
                return 0;
        }
}

/* Pauses a DAG output trace */
static int dag_pause_output(libtrace_out_t *libtrace)
{
        /* Stop and detach the stream */
        if (dag_stop_stream(FORMAT_DATA_OUT->device->fd,
                            FORMAT_DATA_OUT->dagstream) < 0) {
                trace_set_err_out(libtrace, errno, "Could not stop DAG stream");
                return -1;
        }
        if (dag_detach_stream(FORMAT_DATA_OUT->device->fd,
                              FORMAT_DATA_OUT->dagstream) < 0) {
                trace_set_err_out(libtrace, errno,
                                  "Could not detach DAG stream");
                return -1;
        }
        FORMAT_DATA_OUT->stream_attached = 0;
        return 0;
}

/* Pauses a DAG input trace */
static int dag_pause_input(libtrace_t *libtrace)
{
        libtrace_list_node_t *tmp = FORMAT_DATA_HEAD;

        /* Stop and detach each stream */
        while (tmp != NULL) {
                if (dag_stop_stream(FORMAT_DATA->device->fd,
                                    STREAM_DATA(tmp)->dagstream) < 0) {
                        trace_set_err(libtrace, errno,
                                      "Could not stop DAG stream");
                        return -1;
                }
                if (dag_detach_stream(FORMAT_DATA->device->fd,
                                      STREAM_DATA(tmp)->dagstream) < 0) {
                        trace_set_err(libtrace, errno,
                                      "Could not detach DAG stream");
                        return -1;
                }

                tmp = tmp->next;
        }

        FORMAT_DATA->stream_attached = 0;
        return 0;
}



/* Closes a DAG input trace */
static int dag_fin_input(libtrace_t *libtrace)
{
        /* Need the lock, since we're going to be handling the device list */
        pthread_mutex_lock(&open_dag_mutex);

        /* Detach the stream if we are not paused */
        if (FORMAT_DATA->stream_attached)
                dag_pause_input(libtrace);
        FORMAT_DATA->device->ref_count--;

        /* Close the DAG device if there are no more references to it */
        if (FORMAT_DATA->device->ref_count == 0)
                dag_close_device(FORMAT_DATA->device);

        if (DUCK.dummy_duck)
                trace_destroy_dead(DUCK.dummy_duck);

        /* Clear the list */
        libtrace_list_deinit(FORMAT_DATA->per_stream);
        free(libtrace->format_data);
        pthread_mutex_unlock(&open_dag_mutex);
        return 0; /* success */
}

/* Closes a DAG output trace */
static int dag_fin_output(libtrace_out_t *libtrace)
{

        /* Commit any outstanding traffic in the txbuffer */
        if (FORMAT_DATA_OUT->waiting) {
                dag_tx_stream_commit_bytes(FORMAT_DATA_OUT->device->fd,
                                           FORMAT_DATA_OUT->dagstream,
                                           FORMAT_DATA_OUT->waiting );
        }

        /* Wait until the buffer is nearly clear before exiting the program,
         * as we will lose packets otherwise */
        dag_tx_get_stream_space64
                (FORMAT_DATA_OUT->device->fd,
                 FORMAT_DATA_OUT->dagstream,
                 dag_get_stream_buffer_size64(FORMAT_DATA_OUT->device->fd,
                                            FORMAT_DATA_OUT->dagstream) - 8);

        /* Need the lock, since we're going to be handling the device list */
        pthread_mutex_lock(&open_dag_mutex);

        /* Detach the stream if we are not paused */
        if (FORMAT_DATA_OUT->stream_attached)
                dag_pause_output(libtrace);
        FORMAT_DATA_OUT->device->ref_count --;

        /* Close the DAG device if there are no more references to it */
        if (FORMAT_DATA_OUT->device->ref_count == 0)
                dag_close_device(FORMAT_DATA_OUT->device);
        free(libtrace->format_data);
        pthread_mutex_unlock(&open_dag_mutex);
        return 0; /* success */
}

#ifdef DAGIOC_CARD_DUCK
#define LIBTRACE_DUCK_IOCTL DAGIOC_CARD_DUCK
#define LIBTRACE_DUCK_VERSION TRACE_RT_DUCK_5_0
#else 
#ifdef DAGIOCDUCK
#define LIBTRACE_DUCK_IOCTL DAGIOCDUCK
#define LIBTRACE_DUCK_VERSION TRACE_RT_DUCK_2_5
#else
#warning "DAG appears to be missing DUCK support"
#endif
#endif

/* Extracts DUCK information from the DAG card and produces a DUCK packet */
static int dag_get_duckinfo(libtrace_t *libtrace,
                                libtrace_packet_t *packet) {

        if (DUCK.duck_freq == 0)
                return 0;

#ifndef LIBTRACE_DUCK_IOCTL
        trace_set_err(libtrace, errno, 
                "Requested DUCK information but unable to determine the correct ioctl for DUCK");
        DUCK.duck_freq = 0;
        return -1;
#endif

        if (DUCK.last_pkt - DUCK.last_duck < DUCK.duck_freq)
                return 0;

        /* Allocate memory for the DUCK data */
        if (packet->buf_control == TRACE_CTRL_EXTERNAL ||
            !packet->buffer) {
                packet->buffer = malloc(LIBTRACE_PACKET_BUFSIZE);
                packet->buf_control = TRACE_CTRL_PACKET;
                if (!packet->buffer) {
                        trace_set_err(libtrace, errno,
                                      "Cannot allocate packet buffer");
                        return -1;
                }
        }

        /* DUCK doesn't have a format header */
        packet->header = 0;
        packet->payload = packet->buffer;

        /* No need to check if we can get DUCK or not - we're modern
         * enough so just grab the DUCK info */
        if ((ioctl(FORMAT_DATA->device->fd, LIBTRACE_DUCK_IOCTL,
                   (duckinf_t *)packet->payload) < 0)) {
                trace_set_err(libtrace, errno, "Error using DUCK ioctl");
                DUCK.duck_freq = 0;
                return -1;
        }

        packet->type = LIBTRACE_DUCK_VERSION;

        /* Set the packet's trace to point at a DUCK trace, so that the
         * DUCK format functions will be called on the packet rather than the
         * DAG ones */
        if (!DUCK.dummy_duck)
                DUCK.dummy_duck = trace_create_dead("duck:dummy");
        packet->trace = DUCK.dummy_duck;
        DUCK.last_duck = DUCK.last_pkt;
        packet->error = sizeof(duckinf_t);
        return sizeof(duckinf_t);
}

/* Determines the amount of data available to read from the DAG card */
static int dag_available(libtrace_t *libtrace,
                         struct dag_per_stream_t *stream_data)
{
        uint32_t diff = stream_data->top - stream_data->bottom;

        /* If we've processed more than 4MB of data since we last called
         * dag_advance_stream, then we should call it again to allow the
         * space occupied by that 4MB to be released */
        if (diff >= dag_record_size && stream_data->processed < 4 * 1024 * 1024)
                return diff;

        /* Update the top and bottom pointers */
        stream_data->top = dag_advance_stream(FORMAT_DATA->device->fd,
                                              stream_data->dagstream,
                                              &(stream_data->bottom));

        if (stream_data->top == NULL) {
                trace_set_err(libtrace, errno, "dag_advance_stream failed!");
                return -1;
        }
        stream_data->processed = 0;
        diff = stream_data->top - stream_data->bottom;
        return diff;
}

/* Returns a pointer to the start of the next complete ERF record */
static dag_record_t *dag_get_record(struct dag_per_stream_t *stream_data)
{
        dag_record_t *erfptr = NULL;
        uint16_t size;

        erfptr = (dag_record_t *)stream_data->bottom;
        if (!erfptr)
                return NULL;

        size = ntohs(erfptr->rlen);
        if (size < dag_record_size) {
                fprintf(stderr, "DAG2.5 rlen is invalid (rlen %u, must be at least %u\n",
                        size, dag_record_size);
                return NULL;
        }

        /* Make certain we have the full packet available */
        if (size > (stream_data->top - stream_data->bottom))
                return NULL;

        stream_data->bottom += size;
        stream_data->processed += size;
        return erfptr;
}

/* Converts a buffer containing a recently read DAG packet record into a
 * libtrace packet */
static int dag_prepare_packet_stream(libtrace_t *libtrace,
                                     struct dag_per_stream_t *stream_data,
                                     libtrace_packet_t *packet,
                                     void *buffer, libtrace_rt_types_t rt_type,
                                     uint32_t flags)
{
        dag_record_t *erfptr;

        /* If the packet previously owned a buffer that is not the buffer
         * that contains the new packet data, we're going to need to free the
         * old one to avoid memory leaks */
        if (packet->buffer != buffer &&
            packet->buf_control == TRACE_CTRL_PACKET) {
                free(packet->buffer);
        }

        /* Set the buffer owner appropriately */
        if ((flags & TRACE_PREP_OWN_BUFFER) == TRACE_PREP_OWN_BUFFER) {
                packet->buf_control = TRACE_CTRL_PACKET;
        } else
                packet->buf_control = TRACE_CTRL_EXTERNAL;

        /* Update the packet pointers and type appropriately */
        erfptr = (dag_record_t *)buffer;
        packet->buffer = erfptr;
        packet->header = erfptr;
        packet->type = rt_type;

        if (erfptr->flags.rxerror == 1) {
                /* rxerror means the payload is corrupt - drop the payload
                 * by tweaking rlen */
                packet->payload = NULL;
                erfptr->rlen = htons(erf_get_framing_length(packet));
        } else {
                packet->payload = (char*)packet->buffer
                        + erf_get_framing_length(packet);
        }

        if (libtrace->format_data == NULL) {
                dag_init_format_data(libtrace);
        }

        /* Update the dropped packets counter */
        /* No loss counter for DSM coloured records - have to use some
         * other API */
        if (erf_is_color_type(erfptr->type)) {
                /* TODO */
        } else {
                /* Use the ERF loss counter */
                if (stream_data->seeninterface[erfptr->flags.iface]
                    == 0) {
                        stream_data->seeninterface[erfptr->flags.iface]
                                = 1;
                } else {
                        stream_data->drops += ntohs(erfptr->lctr);
                }
        }

        return 0;
}

static int dag_prepare_packet(libtrace_t *libtrace, libtrace_packet_t *packet,
                              void *buffer, libtrace_rt_types_t rt_type,
                              uint32_t flags)
{
        return dag_prepare_packet_stream(libtrace, FORMAT_DATA_FIRST, packet,
                                       buffer, rt_type, flags);
}

/*
 * dag_write_packet() at this stage attempts to improve tx performance
 * by delaying sending a dag_tx_stream_commit_bytes() until a threshold
 * has been met. I observed approximately 270% performance increase
 * through this relatively naive tweak. No optimisation of buffer sizes
 * was attempted.
 */

/* Pushes an ERF record onto the transmit stream */
static int dag_dump_packet(libtrace_out_t *libtrace,
                           dag_record_t *erfptr, unsigned int pad,
                           void *buffer)
{
        int size;

        /*
         * If we've got 0 bytes waiting in the txqueue, assume that we
         * haven't requested any space yet, and request some, storing
         * the pointer at FORMAT_DATA_OUT->txbuffer.
         *
         * The amount to request is slightly magical at the moment - it's
         * 16Mebibytes + 128 kibibytes to ensure that we can copy a packet into
         * the buffer and handle overruns.
         */
        if (FORMAT_DATA_OUT->waiting == 0) {
                FORMAT_DATA_OUT->txbuffer =
                        dag_tx_get_stream_space64(FORMAT_DATA_OUT->device->fd,
                                                FORMAT_DATA_OUT->dagstream,
                                                16908288);
        }

        /*
         * Copy the header separately to the body, as we can't guarantee they 
         * are in contiguous memory
         */
        memcpy(FORMAT_DATA_OUT->txbuffer + FORMAT_DATA_OUT->waiting, erfptr,
               (dag_record_size + pad));
        FORMAT_DATA_OUT->waiting += (dag_record_size + pad);

        /*
         * Copy our incoming packet into the outgoing buffer, and increment 
         * our waiting count
         */
        size = ntohs(erfptr->rlen)-(dag_record_size + pad);
        memcpy(FORMAT_DATA_OUT->txbuffer + FORMAT_DATA_OUT->waiting, buffer,
               size);
        FORMAT_DATA_OUT->waiting += size;

        /*
         * If our output buffer has more than 16 Mebibytes in it, commit those 
         * bytes and reset the waiting count to 0.
         * Note: dag_fin_output will also call dag_tx_stream_commit_bytes() in 
         * case there is still data in the buffer at program exit.
         */
        if (FORMAT_DATA_OUT->waiting >= 16*1024*1024) {
                FORMAT_DATA_OUT->txbuffer =
                        dag_tx_stream_commit_bytes(FORMAT_DATA_OUT->device->fd,
                                                   FORMAT_DATA_OUT->dagstream,
                                                   FORMAT_DATA_OUT->waiting);
                FORMAT_DATA_OUT->waiting = 0;
        }

        return size + pad + dag_record_size;
}

/* Attempts to determine a suitable ERF type for a given packet. Returns true
 * if one is found, false otherwise */
static bool find_compatible_linktype(libtrace_out_t *libtrace,
                                     libtrace_packet_t *packet, char *type)
{
        /* Keep trying to simplify the packet until we can find
         * something we can do with it */

        do {
                *type = libtrace_to_erf_type(trace_get_link_type(packet));

                /* Success */
                if (*type != (char)-1)
                        return true;

                if (!demote_packet(packet)) {
                        trace_set_err_out(libtrace,
                                          TRACE_ERR_NO_CONVERSION,
                                          "No erf type for packet (%i)",
                                          trace_get_link_type(packet));
                        return false;
                }

        } while(1);

        return true;
}

/* Writes a packet to the provided DAG output trace */
static int dag_write_packet(libtrace_out_t *libtrace, libtrace_packet_t *packet)
{
        /* Check dag can write this type of packet */
        if (!dag_can_write(packet)) {
                return 0;
        }

        /* This is heavily borrowed from erf_write_packet(). Yes, CnP
         * coding sucks, sorry about that.
         */
        unsigned int pad = 0;
        int numbytes;
        void *payload = packet->payload;
        dag_record_t *header = (dag_record_t *)packet->header;
        char erf_type = 0;

        if(!packet->header) {
                /* No header, probably an RT packet. Lifted from
                 * erf_write_packet(). */
                return -1;
        }

        pad = dag_get_padding(packet);

        /*
         * If the payload is null, adjust the rlen. Discussion of this is
         * attached to erf_write_packet()
         */
        if (payload == NULL) {
                header->rlen = htons(dag_record_size + pad);
        }

        if (packet->type == TRACE_RT_DATA_ERF) {
                numbytes = dag_dump_packet(libtrace, header, pad, payload);
        } else {
                /* Build up a new packet header from the existing header */

                /* Simplify the packet first - if we can't do this, break
                 * early */
                if (!find_compatible_linktype(libtrace,packet,&erf_type))
                        return -1;

                dag_record_t erfhdr;

                erfhdr.ts = bswap_host_to_le64(trace_get_erf_timestamp(packet));
                payload=packet->payload;
                pad = dag_get_padding(packet);

                /* Flags. Can't do this */
                memset(&erfhdr.flags,1,sizeof(erfhdr.flags));
                if (trace_get_direction(packet)!=(int)~0U)
                        erfhdr.flags.iface = trace_get_direction(packet);

                erfhdr.type = erf_type;

                /* Packet length (rlen includes format overhead) */
                if (trace_get_capture_length(packet) <= 0
                       || trace_get_capture_length(packet) > 65536) {
                        trace_set_err_out(libtrace, TRACE_ERR_BAD_PACKET,
                                "Capture length is out of range in dag_write_packet()");
                        return -1;
                }
                if (erf_get_framing_length(packet) <= 0
                       || trace_get_framing_length(packet) > 65536) {
                        trace_set_err_out(libtrace, TRACE_ERR_BAD_PACKET,
                                "Framing length is out of range in dag_write_packet()");
                        return -1;
                }
                if (trace_get_capture_length(packet) +
                       erf_get_framing_length(packet) <= 0
                       || trace_get_capture_length(packet) +
                       erf_get_framing_length(packet) > 65536) {
                        trace_set_err_out(libtrace, TRACE_ERR_BAD_PACKET,
                                "Capture + framing length is out of range in dag_write_packet()");
                        return -1;
                }

                erfhdr.rlen = htons(trace_get_capture_length(packet)
                                    + erf_get_framing_length(packet));


                /* Loss counter. Can't do this */
                erfhdr.lctr = 0;
                /* Wire length, does not include padding! */
                erfhdr.wlen = htons(trace_get_wire_length(packet));

                /* Write it out */
                numbytes = dag_dump_packet(libtrace, &erfhdr, pad, payload);
        }

        return numbytes;
}

/* Reads the next available packet from a DAG card, in a BLOCKING fashion
 *
 * If DUCK reporting is enabled, the packet returned may be a DUCK update
 */
static int dag_read_packet_stream(libtrace_t *libtrace,
                                struct dag_per_stream_t *stream_data,
                                libtrace_thread_t *t, /* Optional */
                                libtrace_packet_t *packet)
{
        int size = 0;
        dag_record_t *erfptr = NULL;
        struct timeval tv;
        int numbytes = 0;
        uint32_t flags = 0;
        struct timeval maxwait, pollwait;

        pollwait.tv_sec = 0;
        pollwait.tv_usec = 10000;
        maxwait.tv_sec = 0;
        maxwait.tv_usec = 250000;

        /* Check if we're due for a DUCK report - only report on the first thread */
        if (stream_data == FORMAT_DATA_FIRST) {
                size = dag_get_duckinfo(libtrace, packet);
                if (size != 0)
                        return size;
        }


        /* Don't let anyone try to free our DAG memory hole! */
        flags |= TRACE_PREP_DO_NOT_OWN_BUFFER;

        /* If the packet buffer is currently owned by libtrace, free it so
         * that we can set the packet to point into the DAG memory hole */
        if (packet->buf_control == TRACE_CTRL_PACKET) {
                free(packet->buffer);
                packet->buffer = 0;
        }

        if (dag_set_stream_poll64(FORMAT_DATA->device->fd, stream_data->dagstream,
                                sizeof(dag_record_t), &maxwait,
                                &pollwait) == -1) {
                trace_set_err(libtrace, errno, "dag_set_stream_poll");
                return -1;
        }

        /* Grab a full ERF record */
        do {
                numbytes = dag_available(libtrace, stream_data);
                if (numbytes < 0)
                        return numbytes;
                if (numbytes < dag_record_size) {
                        /* Check the message queue if we have one to check */
                        if (t != NULL &&
                            libtrace_message_queue_count(&t->messages) > 0)
                                return -2;

                        if ((numbytes=is_halted(libtrace)) != -1)
                                return numbytes;
                        /* Block until we see a packet */
                        continue;
                }
                erfptr = dag_get_record(stream_data);
        } while (erfptr == NULL);

        packet->trace = libtrace;

        /* Prepare the libtrace packet */
        if (dag_prepare_packet_stream(libtrace, stream_data, packet, erfptr,
                                    TRACE_RT_DATA_ERF, flags))
                return -1;

        /* Update the DUCK timer - don't re-order this check (false-sharing) */
        if (stream_data == FORMAT_DATA_FIRST && DUCK.duck_freq != 0) {
                tv = trace_get_timeval(packet);
                DUCK.last_pkt = tv.tv_sec;
        }

        packet->order = erf_get_erf_timestamp(packet);
        packet->error = packet->payload ? htons(erfptr->rlen) :
                                          erf_get_framing_length(packet);

        return packet->error;
}

static int dag_read_packet(libtrace_t *libtrace, libtrace_packet_t *packet)
{
        return dag_read_packet_stream(libtrace, FORMAT_DATA_FIRST, NULL, packet);
}

static int dag_pread_packets(libtrace_t *libtrace, libtrace_thread_t *t,
                             libtrace_packet_t **packets, size_t nb_packets)
{
        int ret;
        size_t read_packets = 0;
        int numbytes = 0;

        struct dag_per_stream_t *stream_data =
                (struct dag_per_stream_t *)t->format_data;

        /* Read as many packets as we can, but read atleast one packet */
        do {
                ret = dag_read_packet_stream(libtrace, stream_data, t,
                                           packets[read_packets]);
                if (ret < 0)
                        return ret;

                read_packets++;

                /* Make sure we don't read too many packets..! */
                if (read_packets >= nb_packets)
                        break;

                numbytes = dag_available(libtrace, stream_data);
        } while (numbytes >= dag_record_size);

        return read_packets;
}

/* Attempts to read a packet from a DAG card in a NON-BLOCKING fashion. If a
 * packet is available, we will return a packet event. Otherwise we will
 * return a SLEEP event (as we cannot select on the DAG file descriptor).
 */
static libtrace_eventobj_t trace_event_dag(libtrace_t *libtrace,
                                           libtrace_packet_t *packet)
{
        libtrace_eventobj_t event = {0,0,0.0,0};
        dag_record_t *erfptr = NULL;
        int numbytes;
        uint32_t flags = 0;
        struct timeval minwait, tv;
        
        minwait.tv_sec = 0;
        minwait.tv_usec = 10000;

        /* Check if we're meant to provide a DUCK update */
        numbytes = dag_get_duckinfo(libtrace, packet);
        if (numbytes < 0) {
                event.type = TRACE_EVENT_TERMINATE;
                return event;
        } else if (numbytes > 0) {
                event.type = TRACE_EVENT_PACKET;
                return event;
        }
        
        if (dag_set_stream_poll64(FORMAT_DATA->device->fd,
                                FORMAT_DATA_FIRST->dagstream, 0, &minwait,
                                &minwait) == -1) {
                trace_set_err(libtrace, errno, "dag_set_stream_poll");
                event.type = TRACE_EVENT_TERMINATE;
                return event;
        }

        do {
                erfptr = NULL;
                numbytes = 0;

                /* Need to call dag_available so that the top pointer will get
                 * updated, otherwise we'll never see any data! */
                numbytes = dag_available(libtrace, FORMAT_DATA_FIRST);

                /* May as well not bother calling dag_get_record if
                 * dag_available suggests that there's no data */
                if (numbytes != 0)
                        erfptr = dag_get_record(FORMAT_DATA_FIRST);
                if (erfptr == NULL) {
                        /* No packet available - sleep for a very short time */
                        if (libtrace_halt) {
                                event.type = TRACE_EVENT_TERMINATE;
                        } else {
                                event.type = TRACE_EVENT_SLEEP;
                                event.seconds = 0.0001;
                        }
                        break;
                }
                if (dag_prepare_packet_stream(libtrace, FORMAT_DATA_FIRST, packet,
                                            erfptr, TRACE_RT_DATA_ERF, flags)) {
                        event.type = TRACE_EVENT_TERMINATE;
                        break;
                }


                event.size = trace_get_capture_length(packet) +
                        trace_get_framing_length(packet);

                /* XXX trace_read_packet() normally applies the following
                 * config options for us, but this function is called via
                 * trace_event() so we have to do it ourselves */

                if (libtrace->filter) {
                        int filtret = trace_apply_filter(libtrace->filter,
                                                         packet);
                        if (filtret == -1) {
                                trace_set_err(libtrace, TRACE_ERR_BAD_FILTER,
                                              "Bad BPF Filter");
                                event.type = TRACE_EVENT_TERMINATE;
                                break;
                        }

                        if (filtret == 0) {
                                /* This packet isn't useful so we want to
                                 * immediately see if there is another suitable
                                 * one - we definitely DO NOT want to return
                                 * a sleep event in this case, like we used to
                                 * do! */
                                libtrace->filtered_packets ++;
                                trace_clear_cache(packet);
                                continue;
                        }

                        event.type = TRACE_EVENT_PACKET;
                } else {
                        event.type = TRACE_EVENT_PACKET;
                }

                /* Update the DUCK timer */
                tv = trace_get_timeval(packet);
                DUCK.last_pkt = tv.tv_sec;
                
                if (libtrace->snaplen > 0) {
                        trace_set_capture_length(packet, libtrace->snaplen);
                }
                libtrace->accepted_packets ++;
                break;
        } while(1);

        return event;
}

static void dag_get_statistics(libtrace_t *libtrace, libtrace_stat_t *stat)
{
        libtrace_list_node_t *tmp;
        if (!libtrace) {
                fprintf(stderr, "NULL trace passed into dag_get_statistics()\n");
                return;
        }
        if (!stat) {
                trace_set_err(libtrace, TRACE_ERR_STAT, "NULL stat passed into dag_get_statistics()");
                return;
        }
        tmp = FORMAT_DATA_HEAD;

        /* Dropped packets */
        stat->dropped_valid = 1;
        stat->dropped = 0;
        while (tmp != NULL) {
                stat->dropped += STREAM_DATA(tmp)->drops;
                tmp = tmp->next;
        }

}

static void dag_get_thread_statistics(libtrace_t *libtrace, libtrace_thread_t *t,
                                       libtrace_stat_t *stat) {
        struct dag_per_stream_t *stream_data = t->format_data;
        if (!libtrace) {
                fprintf(stderr, "NULL trace passed into dag_get_thread_statistics()\n");
                return;
        }
        if (!stat) {
                trace_set_err(libtrace, TRACE_ERR_STAT, "NULL stat passed into dag_get_thread_statistics()");
                return;
        }
        stat->dropped_valid = 1;
        stat->dropped = stream_data->drops;

        stat->filtered_valid = 1;
        stat->filtered = 0;
}

/* Prints some semi-useful help text about the DAG format module */
static void dag_help(void) {
        printf("dag format module: $Revision: 1755 $\n");
        printf("Supported input URIs:\n");
        printf("\tdag:/dev/dagn\n");
        printf("\n");
        printf("\te.g.: dag:/dev/dag0\n");
        printf("\n");
        printf("Supported output URIs:\n");
        printf("\tnone\n");
        printf("\n");
}

static int dag_pregister_thread(libtrace_t *libtrace, libtrace_thread_t *t,
                                bool reader)
{
        struct dag_per_stream_t *stream_data;
        libtrace_list_node_t *node;

        if (reader && t->type == THREAD_PERPKT) {
                node = libtrace_list_get_index(FORMAT_DATA->per_stream,
                                                t->perpkt_num);
                if (node == NULL) {
                        return -1;
                }
                stream_data = node->data;

                /* Pass the per thread data to the thread */
                t->format_data = stream_data;

                /* Attach and start the DAG stream */
                if (dag_start_input_stream(libtrace, stream_data) < 0)
                        return -1;
        }

        return 0;
}

static struct libtrace_format_t dag = {
        "dag",
        "$Id$",
        TRACE_FORMAT_ERF,
        dag_probe_filename,             /* probe filename */
        NULL,                           /* probe magic */
        dag_init_input,                 /* init_input */
        dag_config_input,               /* config_input */
        dag_start_input,                /* start_input */
        dag_pause_input,                /* pause_input */
        dag_init_output,                /* init_output */
        NULL,                           /* config_output */
        dag_start_output,               /* start_output */
        dag_fin_input,                  /* fin_input */
        dag_fin_output,                 /* fin_output */
        dag_read_packet,                /* read_packet */
        dag_prepare_packet,             /* prepare_packet */
        NULL,                           /* fin_packet */
        dag_write_packet,               /* write_packet */
        NULL,                           /* flush_output */
        erf_get_link_type,              /* get_link_type */
        erf_get_direction,              /* get_direction */
        erf_set_direction,              /* set_direction */
        erf_get_erf_timestamp,          /* get_erf_timestamp */
        NULL,                           /* get_timeval */
        NULL,                           /* get_seconds */
        NULL,                           /* get_timespec */
        NULL,                           /* get_meta_section */
        NULL,                           /* seek_erf */
        NULL,                           /* seek_timeval */
        NULL,                           /* seek_seconds */
        erf_get_capture_length,         /* get_capture_length */
        erf_get_wire_length,            /* get_wire_length */
        erf_get_framing_length,         /* get_framing_length */
        erf_set_capture_length,         /* set_capture_length */
        NULL,                           /* get_received_packets */
        NULL,                           /* get_filtered_packets */
        NULL,                           /* get_dropped_packets */
        dag_get_statistics,             /* get_statistics */
        NULL,                           /* get_fd */
        trace_event_dag,                /* trace_event */
        dag_help,                       /* help */
        NULL,                            /* next pointer */
        {true, 0}, /* live packet capture, thread limit TBD */
        dag_pstart_input,
        dag_pread_packets,
        dag_pause_input,
        NULL,
        dag_pregister_thread,
        NULL,
        dag_get_thread_statistics       /* get thread stats */
};

void dag_constructor(void)
{
        register_format(&dag);
}