source: trunk/lib/trace.c @ 1602

/*
 * 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 
 *          
 * 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
 *
 * $Id$
 *
 */


#define _GNU_SOURCE
#include "common.h"
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifndef WIN32
#include <sys/socket.h>
#endif
#include <stdarg.h>

#ifdef HAVE_LIMITS_H
#  include <limits.h>
#endif

#ifdef HAVE_SYS_LIMITS_H
#  include <sys/limits.h>
#endif

#ifdef HAVE_NET_IF_ARP_H
#  include <net/if_arp.h>
#endif

#ifdef HAVE_NET_IF_H
#  include <net/if.h>
#endif

#ifdef HAVE_NETINET_IN_H
#  include <netinet/in.h>
#endif

#ifdef HAVE_NET_ETHERNET_H
#  include <net/ethernet.h>
#endif

#ifdef HAVE_NETINET_IF_ETHER_H
#  include <netinet/if_ether.h>
#endif

#include <time.h>
#ifdef WIN32
#include <sys/timeb.h>
#endif

#include "libtrace.h"
#include "libtrace_int.h"

#ifdef HAVE_PCAP_BPF_H
#  include <pcap-bpf.h>
#else
#  ifdef HAVE_NET_BPF_H
#    include <net/bpf.h>
#  endif
#endif


#include "libtrace_int.h"
#include "format_helper.h"
#include "rt_protocol.h"

#define MAXOPTS 1024

/* This file contains much of the implementation of the libtrace API itself. */

static struct libtrace_format_t *formats_list = NULL;

/* strncpy is not assured to copy the final \0, so we
 * will use our own one that does
 */
static void xstrncpy(char *dest, const char *src, size_t n)
{
        strncpy(dest,src,n);
        dest[n]='\0';
}
 
static char *xstrndup(const char *src,size_t n)
{       
        char *ret=(char*)malloc(n+1);
        if (ret==NULL) {
                fprintf(stderr,"Out of memory");
                exit(EXIT_FAILURE);
        }
        xstrncpy(ret,src,n);
        return ret;
}


/* call all the constructors if they haven't yet all been called */
static void trace_init(void)
{
        if (!formats_list) {
                duck_constructor();
                erf_constructor();
                tsh_constructor();
                legacy_constructor();
                atmhdr_constructor();
#ifdef HAVE_NETPACKET_PACKET_H
                linuxnative_constructor();
#endif
#ifdef HAVE_LIBPCAP
                pcap_constructor();
#endif
#if HAVE_DECL_BIOCSETIF
                bpf_constructor();
#endif
                pcapfile_constructor();
                rt_constructor();
#ifdef HAVE_DAG
                dag_constructor();
#endif
        }
}

/* Prints help information for libtrace 
 *
 * Function prints out some basic help information regarding libtrace,
 * and then prints out the help() function registered with each input module
 */
DLLEXPORT void trace_help(void) {
        struct libtrace_format_t *tmp;
        trace_init();
        printf("libtrace %s\n\n",PACKAGE_VERSION);
        printf("Following this are a list of the format modules supported in this build of libtrace\n\n");
        for(tmp=formats_list;tmp;tmp=tmp->next) {
                if (tmp->help)
                        tmp->help();
        }
}

#define URI_PROTO_LINE 16U

/* Try to guess which format module is appropriate for a given trace file or
 * device */
static void guess_format(libtrace_t *libtrace, const char *filename)
{
        struct libtrace_format_t *tmp;
        
        /* Try and guess based on filename */
        for(tmp = formats_list; tmp; tmp=tmp->next) {
                if (tmp->probe_filename && tmp->probe_filename(filename)) {
                        libtrace->format = tmp;
                        libtrace->uridata = strdup(filename);
                        return;
                }
        }

        libtrace->io = wandio_create(filename);
        if (!libtrace->io)
                return;

        /* Try and guess based on file magic */
        for(tmp = formats_list; tmp; tmp=tmp->next) {
                if (tmp->probe_magic && tmp->probe_magic(libtrace->io)) {
                        libtrace->format = tmp;
                        libtrace->uridata = strdup(filename);
                        return;
                }
        }
        
        /* Oh well */
        return;
}

/* Creates an input trace from a URI
 *
 * @params char * containing a valid libtrace URI
 * @returns opaque pointer to a libtrace_t
 *
 * Some valid URI's are:
 *  erf:/path/to/erf/file
 *  erf:/path/to/erf/file.gz
 *  erf:-                       (stdin)
 *  dag:/dev/dagcard
 *  pcapint:pcapinterface               (eg: pcapint:eth0)
 *  pcapfile:/path/to/pcap/file
 *  pcapfile:-
 *  int:interface                       (eg: int:eth0) only on Linux
 *  rt:hostname
 *  rt:hostname:port
 *
 * If an error occured when attempting to open a trace, NULL is returned
 * and an error is output to stdout.
 */
DLLEXPORT libtrace_t *trace_create(const char *uri) {
        libtrace_t *libtrace = 
                        (libtrace_t *)malloc(sizeof(libtrace_t));
        char *scan = 0;
        const char *uridata = 0;                  

        trace_init();

        assert(uri && "Passing NULL to trace_create makes me a very sad program");

        if (!libtrace) {
                /* Out of memory */
                return NULL;
        }
        
        libtrace->err.err_num = TRACE_ERR_NOERROR;
        libtrace->format=NULL;
        
        libtrace->event.tdelta = 0.0;
        libtrace->event.packet = NULL;
        libtrace->event.psize = 0;
        libtrace->event.trace_last_ts = 0.0;
        libtrace->filter = NULL;
        libtrace->snaplen = 0;
        libtrace->started=false;
        libtrace->uridata = NULL;
        libtrace->io = NULL;
        libtrace->filtered_packets = 0;

        /* Parse the URI to determine what sort of trace we are dealing with */
        if ((uridata = trace_parse_uri(uri, &scan)) == 0) {
                /* Could not parse the URI nicely */
                guess_format(libtrace,uri);
                if (!libtrace->format) {
                        trace_set_err(libtrace,TRACE_ERR_BAD_FORMAT,"Unable to guess format (%s)",uri);
                        return libtrace;
                }
        }
        else {
                struct libtrace_format_t *tmp;

                /* Find a format that matches the first part of the URI */
                for (tmp=formats_list;tmp;tmp=tmp->next) {
                        if (strlen(scan) == strlen(tmp->name) &&
                                        strncasecmp(scan, tmp->name, strlen(scan)) == 0
                                        ) {
                                libtrace->format=tmp;
                                break;
                        }
                }

                if (libtrace->format == 0) {
                        trace_set_err(libtrace, TRACE_ERR_BAD_FORMAT,
                                        "Unknown format (%s)",scan);
                        return libtrace;
                }

                libtrace->uridata = strdup(uridata);
        }
        /* libtrace->format now contains the type of uri
         * libtrace->uridata contains the appropriate data for this
         */
       
        /* Call the init_input function for the matching capture format */ 
        if (libtrace->format->init_input) {
                int err=libtrace->format->init_input(libtrace);
                assert (err==-1 || err==0);
                if (err==-1) {
                        /* init_input should call trace_set_err to set 
                         * the error message
                         */
                        return libtrace;
                }
        } else {
                trace_set_err(libtrace,TRACE_ERR_UNSUPPORTED,
                                "Format does not support input (%s)",scan);
                return libtrace;
        }
        

        free(scan);
        libtrace->err.err_num=TRACE_ERR_NOERROR;
        libtrace->err.problem[0]='\0';
        return libtrace;
}

/* Creates a "dummy" trace file that has only the format type set.
 *
 * @returns opaque pointer to a (sparsely initialised) libtrace_t
 *
 * IMPORTANT: Do not attempt to call trace_read_packet or other such functions
 * with the dummy trace. Its intended purpose is to act as a packet->trace for
 * libtrace_packet_t's that are not associated with a libtrace_t structure.
 */
DLLEXPORT libtrace_t * trace_create_dead (const char *uri) {
        libtrace_t *libtrace = (libtrace_t *) malloc(sizeof(libtrace_t));
        char *scan = (char *)calloc(sizeof(char),URI_PROTO_LINE);
        char *uridata;
        struct libtrace_format_t *tmp;

        trace_init();
        
        libtrace->err.err_num = TRACE_ERR_NOERROR;

        if((uridata = strchr(uri,':')) == NULL) {
                xstrncpy(scan, uri, strlen(uri));
        } else {
                xstrncpy(scan,uri, (size_t)(uridata - uri));
        }
        
        libtrace->err.err_num = TRACE_ERR_NOERROR;
        libtrace->format=NULL;
        
        libtrace->event.tdelta = 0.0;
        libtrace->event.packet = NULL;
        libtrace->event.psize = 0;
        libtrace->event.trace_last_ts = 0.0;
        libtrace->filter = NULL;
        libtrace->snaplen = 0;
        libtrace->started=false;
        libtrace->uridata = NULL;
        libtrace->io = NULL;
        libtrace->filtered_packets = 0;
        
        for(tmp=formats_list;tmp;tmp=tmp->next) {
                if (strlen(scan) == strlen(tmp->name) &&
                                !strncasecmp(scan,
                                        tmp->name,
                                        strlen(scan))) {
                                libtrace->format=tmp;
                                break;
                                }
        }
        if (libtrace->format == 0) {
                trace_set_err(libtrace,TRACE_ERR_BAD_FORMAT,
                                "Unknown format (%s)",scan);
        }

        libtrace->format_data = NULL;
        free(scan);
        return libtrace;

}

/* Creates an output trace from a URI. 
 *
 * @param uri   the uri string describing the output format and destination
 * @returns opaque pointer to a libtrace_output_t 
 *
 *  If an error occured when attempting to open the output trace, NULL is
 *  returned and trace_errno is set. 
 */
        
DLLEXPORT libtrace_out_t *trace_create_output(const char *uri) {
        libtrace_out_t *libtrace = 
                        (libtrace_out_t*)malloc(sizeof(libtrace_out_t));
        
        char *scan = 0;
        const char *uridata = 0;
        struct libtrace_format_t *tmp;

        trace_init();

        libtrace->err.err_num = TRACE_ERR_NOERROR;
        strcpy(libtrace->err.problem,"Error message set\n");
        libtrace->format = NULL;
        libtrace->uridata = NULL;
        
        /* Parse the URI to determine what capture format we want to write */

        if ((uridata = trace_parse_uri(uri, &scan)) == 0) {
                trace_set_err_out(libtrace,TRACE_ERR_BAD_FORMAT,
                                "Bad uri format (%s)",uri);
                return libtrace;
        }
        
        /* Attempt to find the format in the list of supported formats */
        for(tmp=formats_list;tmp;tmp=tmp->next) {
                if (strlen(scan) == strlen(tmp->name) &&
                                !strncasecmp(scan,
                                        tmp->name,
                                        strlen(scan))) {
                                libtrace->format=tmp;
                                break;
                                }
        }
        free(scan);

        if (libtrace->format == NULL) {
                trace_set_err_out(libtrace,TRACE_ERR_BAD_FORMAT,
                                "Unknown output format (%s)",scan);
                return libtrace;
        }
        libtrace->uridata = strdup(uridata);

        /* libtrace->format now contains the type of uri
         * libtrace->uridata contains the appropriate data for this
         */

        if (libtrace->format->init_output) {
                /* 0 on success, -1 on failure */
                switch(libtrace->format->init_output(libtrace)) {
                        case -1: /* failure */
                                return libtrace;
                        case 0: /* success */
                                break;
                        default:
                                assert(!"Internal error: init_output() should return -1 for failure, or 0 for success");
                }
        } else {
                trace_set_err_out(libtrace,TRACE_ERR_UNSUPPORTED,
                                "Format does not support writing (%s)",scan);
                return libtrace;
        }


        libtrace->started=false;
        return libtrace;
}

/* Start an input trace
 * @param libtrace      the input trace to start
 * @returns 0 on success
 *
 * This does the work associated with actually starting up
 * the trace.  it may fail.
 */
DLLEXPORT int trace_start(libtrace_t *libtrace)
{
        assert(libtrace);
        if (trace_is_err(libtrace))
                return -1;
        if (libtrace->format->start_input) {
                int ret=libtrace->format->start_input(libtrace);
                if (ret < 0) {
                        return ret;
                }
        }

        libtrace->started=true;
        return 0;
}

/* Start an output trace */
DLLEXPORT int trace_start_output(libtrace_out_t *libtrace) 
{
        assert(libtrace);
        if (libtrace->format->start_output) {
                int ret=libtrace->format->start_output(libtrace);
                if (ret < 0) {
                        return ret;
                }
        }

        libtrace->started=true;
        return 0;
}

DLLEXPORT int trace_pause(libtrace_t *libtrace)
{
        assert(libtrace);
        if (!libtrace->started) {
                trace_set_err(libtrace,TRACE_ERR_BAD_STATE, "You must call trace_start() before calling trace_pause()");
                return -1;
        }
        if (libtrace->format->pause_input)
                libtrace->format->pause_input(libtrace);
        libtrace->started=false;
        return 0;
}

DLLEXPORT int trace_config(libtrace_t *libtrace,
                trace_option_t option,
                void *value)
{
        int ret;
        libtrace_err_t err;

        if (trace_is_err(libtrace)) {
                return -1;
        }
        
        /* If the capture format supports configuration, try using their
         * native configuration first */
        if (libtrace->format->config_input) {
                ret=libtrace->format->config_input(libtrace,option,value);
                if (ret==0)
                        return 0;
        }

        /* If we get here, either the native configuration failed or the
         * format did not support configuration. However, libtrace can 
         * deal with some options itself, so give that a go */
        switch(option) {
                case TRACE_OPTION_SNAPLEN:
                        /* Clear the error if there was one */
                        if (trace_is_err(libtrace)) {
                                err = trace_get_err(libtrace);
                        }
                        if (*(int*)value<0 
                                || *(int*)value>LIBTRACE_PACKET_BUFSIZE) {
                                trace_set_err(libtrace,TRACE_ERR_BAD_STATE,
                                        "Invalid snap length");
                        }
                        libtrace->snaplen=*(int*)value;
                        return 0;
                case TRACE_OPTION_FILTER:
                        /* Clear the error if there was one */
                        if (trace_is_err(libtrace)) {
                                err = trace_get_err(libtrace);
                        }
                        libtrace->filter=(libtrace_filter_t *)value;
                        return 0;
                case TRACE_OPTION_PROMISC:
                        if (!trace_is_err(libtrace)) {
                                trace_set_err(libtrace,TRACE_ERR_OPTION_UNAVAIL,
                                                "Promisc mode is not supported by this format module");
                        }
                        return -1;
                case TRACE_OPTION_META_FREQ:
                        if (!trace_is_err(libtrace)) {
                                trace_set_err(libtrace, 
                                                TRACE_ERR_OPTION_UNAVAIL,
                                                "This format does not support meta-data gathering");
                        }
                        return -1;
                case TRACE_OPTION_EVENT_REALTIME:
                        if (!trace_is_err(libtrace)) {
                                trace_set_err(libtrace, 
                                                TRACE_ERR_OPTION_UNAVAIL,
                                                "This format does not support realtime events");
                        }
                        return -1;
                        
        }
        if (!trace_is_err(libtrace)) {
                trace_set_err(libtrace,TRACE_ERR_UNKNOWN_OPTION,
                        "Unknown option %i", option);
        }
        return -1;
}

DLLEXPORT int trace_config_output(libtrace_out_t *libtrace, 
                trace_option_output_t option,
                void *value) {
        
        /* Unlike the input options, libtrace does not natively support any of
         * the output options - the format module must be able to deal with
         * them. */
        if (libtrace->format->config_output) {
                return libtrace->format->config_output(libtrace, option, value);
        }
        return -1;
}

/* Close an input trace file, freeing up any resources it may have been using
 *
 */
DLLEXPORT void trace_destroy(libtrace_t *libtrace) {
        assert(libtrace);
        if (libtrace->format) {
                if (libtrace->started && libtrace->format->pause_input)
                        libtrace->format->pause_input(libtrace);
                libtrace->format->fin_input(libtrace);
        }
        /* Need to free things! */
        if (libtrace->uridata)
                free(libtrace->uridata);
        free(libtrace);
}


DLLEXPORT void trace_destroy_dead(libtrace_t *libtrace) {
        assert(libtrace);

        /* Don't call pause_input or fin_input, because we should never have
         * used this trace to do any reading anyway. Do make sure we free
         * any format_data that has been created, though. */
        if (libtrace->format_data)
                free(libtrace->format_data);
        free(libtrace);
}
/* Close an output trace file, freeing up any resources it may have been using
 *
 * @param libtrace      the output trace file to be destroyed
 */
DLLEXPORT void trace_destroy_output(libtrace_out_t *libtrace) 
{
        assert(libtrace);
        if (libtrace->format && libtrace->format->fin_output)
                libtrace->format->fin_output(libtrace);
        if (libtrace->uridata)
                free(libtrace->uridata);
        free(libtrace);
}

DLLEXPORT libtrace_packet_t *trace_create_packet(void) 
{
        libtrace_packet_t *packet = 
                (libtrace_packet_t*)calloc((size_t)1,sizeof(libtrace_packet_t));

        packet->buf_control=TRACE_CTRL_PACKET;
        packet->capture_length=-1;
        return packet;
}

DLLEXPORT libtrace_packet_t *trace_copy_packet(const libtrace_packet_t *packet) {
        libtrace_packet_t *dest = 
                (libtrace_packet_t *)malloc(sizeof(libtrace_packet_t));
        if (!dest) {
                printf("Out of memory constructing packet\n");
                abort();
        }
        dest->trace=packet->trace;
        dest->buffer=malloc(65536);
        if (!dest->buffer) {
                printf("Out of memory allocating buffer memory\n");
                abort();
        }
        dest->header=dest->buffer;
        dest->payload=(void*)
                ((char*)dest->buffer+trace_get_framing_length(packet));
        dest->type=packet->type;
        dest->buf_control=TRACE_CTRL_PACKET;
        /* Reset the cache - better to recalculate than try to convert
         * the values over to the new packet */
        dest->capture_length = -1;
        dest->l3_header = NULL;
        dest->l3_ethertype = 0;
        
        /* Ooooh nasty memcpys! This is why we want to avoid copying packets
         * as much as possible */
        memcpy(dest->header,packet->header,trace_get_framing_length(packet));
        memcpy(dest->payload,packet->payload,trace_get_capture_length(packet));

        return dest;
}

/** Destroy a packet object
 */
DLLEXPORT void trace_destroy_packet(libtrace_packet_t *packet) {
        if (packet->buf_control == TRACE_CTRL_PACKET) {
                free(packet->buffer);
        }
        packet->buf_control=(buf_control_t)'\0'; 
                                /* A "bad" value to force an assert
                                 * if this packet is ever reused
                                 */
        free(packet);
}       

/* Read one packet from the trace into buffer. Note that this function will
 * block until a packet is read (or EOF is reached).
 *
 * @param libtrace      the libtrace opaque pointer
 * @param packet        the packet opaque pointer
 * @returns 0 on EOF, negative value on error
 *
 */
DLLEXPORT int trace_read_packet(libtrace_t *libtrace, libtrace_packet_t *packet) {

        assert(libtrace && "You called trace_read_packet() with a NULL libtrace parameter!\n");
        if (trace_is_err(libtrace))
                return -1;
        if (!libtrace->started) {
                trace_set_err(libtrace,TRACE_ERR_BAD_STATE,"You must call libtrace_start() before trace_read_packet()\n");
                return -1;
        }
        if (!(packet->buf_control==TRACE_CTRL_PACKET || packet->buf_control==TRACE_CTRL_EXTERNAL)) {
                trace_set_err(libtrace,TRACE_ERR_BAD_STATE,"Packet passed to trace_read_packet() is invalid\n");
                return -1;
        }
        assert(packet);
      
        /* Store the trace we are reading from into the packet opaque 
         * structure */
        packet->trace = libtrace;

        /* Finalise the packet, freeing any resources the format module
         * may have allocated it
         */
        if (libtrace->format->fin_packet) {
                libtrace->format->fin_packet(packet);
        }


        if (libtrace->format->read_packet) {
                do {
                        size_t ret;
                        /* Clear the packet cache */
                        packet->capture_length = -1;
                        packet->l3_header = NULL;
                        packet->l3_ethertype = 0;

                        ret=libtrace->format->read_packet(libtrace,packet);
                        if (ret==(size_t)-1 || ret==0) {
                                return ret;
                        }
                        if (libtrace->filter) {
                                /* If the filter doesn't match, read another
                                 * packet
                                 */
                                if (!trace_apply_filter(libtrace->filter,packet)){
                                        ++libtrace->filtered_packets;
                                        continue;
                                }
                        }
                        if (libtrace->snaplen>0) {
                                /* Snap the packet */
                                trace_set_capture_length(packet,
                                                libtrace->snaplen);
                        }
                        ++libtrace->accepted_packets;
                        return ret;
                } while(1);
        }
        trace_set_err(libtrace,TRACE_ERR_UNSUPPORTED,"This format does not support reading packets\n");
        return ~0U;
}

/* Converts the provided buffer into a libtrace packet of the given type.
 *
 * Unlike trace_construct_packet, the buffer is expected to begin with the
 * appropriate capture format header for the format type that the packet is
 * being converted to. This also allows for a packet to be converted into
 * just about capture format that is supported by libtrace, provided the 
 * format header is present in the buffer.
 *
 * This function is primarily used to convert packets received via the RT
 * protocol back into their original capture format. The RT header encapsulates
 * the original capture format header, so after removing it the packet must 
 * have it's header and payload pointers updated and the packet format and type
 * changed, amongst other things.
 *
 * Intended only for internal use at this point - this function is not 
 * available through the external libtrace API.
 */
int trace_prepare_packet(libtrace_t *trace, libtrace_packet_t *packet,
                void *buffer, libtrace_rt_types_t rt_type, uint32_t flags) {

        assert(packet);
        assert(trace);
        
        /* XXX Proper error handling?? */
        if (buffer == NULL)
                return -1;

        if (!(packet->buf_control==TRACE_CTRL_PACKET || packet->buf_control==TRACE_CTRL_EXTERNAL)) {
                trace_set_err(trace,TRACE_ERR_BAD_STATE,"Packet passed to trace_read_packet() is invalid\n");
                return -1;
        }
        
        packet->trace = trace;
        
        /* Clear packet cache */
        packet->capture_length = -1;
        packet->l3_header = NULL;
        packet->l3_ethertype = 0;

        if (trace->format->prepare_packet) {
                return trace->format->prepare_packet(trace, packet,
                                buffer, rt_type, flags);
        }
        trace_set_err(trace, TRACE_ERR_UNSUPPORTED, 
                        "This format does not support preparing packets\n");
        return -1;

}

/* Writes a packet to the specified output trace
 *
 * @param libtrace      describes the output format, destination, etc.
 * @param packet        the packet to be written out
 * @returns the number of bytes written, -1 if write failed
 */
DLLEXPORT int trace_write_packet(libtrace_out_t *libtrace, libtrace_packet_t *packet) {
        assert(libtrace);
        assert(packet); 
        /* Verify the packet is valid */
        if (!libtrace->started) {
                trace_set_err_out(libtrace,TRACE_ERR_BAD_STATE,
                        "Trace is not started before trace_write_packet");
                return -1;
        }

        if (libtrace->format->write_packet) {
                return libtrace->format->write_packet(libtrace, packet);
        }
        trace_set_err_out(libtrace,TRACE_ERR_UNSUPPORTED,
                "This format does not support writing packets");
        return -1;
}

/* Get a pointer to the first byte of the packet payload */
DLLEXPORT void *trace_get_packet_buffer(const libtrace_packet_t *packet,
                libtrace_linktype_t *linktype, uint32_t *remaining) {
        int cap_len;
        int wire_len;

        assert(packet != NULL);
        if (linktype) *linktype = trace_get_link_type(packet);
        if (remaining) {
                /* I think we should choose the minimum of the capture and
                 * wire lengths to be the "remaining" value. If the packet has
                 * been padded to increase the capture length, we don't want
                 * to allow subsequent protocol decoders to consider the 
                 * padding as part of the packet.
                 *
                 * For example, in Auck 4 there is a trace where the IP header
                 * length is incorrect (24 bytes) followed by a 20 byte TCP
                 * header. Total IP length is 40 bytes. As a result, the
                 * legacyatm padding gets treated as the "missing" bytes of
                 * the TCP header, which isn't the greatest. We're probably
                 * better off returning an incomplete TCP header in that case.
                 */
                
                cap_len = trace_get_capture_length(packet);
                wire_len = trace_get_wire_length(packet);

                assert(cap_len >= 0 && wire_len >= 0);
                if (wire_len < cap_len)
                        *remaining = wire_len;
                else
                        *remaining = cap_len;
                /* *remaining = trace_get_capture_length(packet); */
        }
        return (void *) packet->payload;
}


/* Get a pointer to the first byte of the packet payload 
 *
 * DEPRECATED - use trace_get_packet_buffer() instead */
DLLEXPORT void *trace_get_link(const libtrace_packet_t *packet) {
        return (void *)packet->payload;
}

/* Get the current time in DAG time format 
 * @param packet        a pointer to a libtrace_packet structure
 * @returns a 64 bit timestamp in DAG ERF format (upper 32 bits are the seconds
 * past 1970-01-01, the lower 32bits are partial seconds)
 */ 
DLLEXPORT uint64_t trace_get_erf_timestamp(const libtrace_packet_t *packet) {
        if (packet->trace->format->get_erf_timestamp) {
                /* timestamp -> timestamp */
                return packet->trace->format->get_erf_timestamp(packet);
        } else if (packet->trace->format->get_timespec) {
                /* timespec -> timestamp */
                struct timespec ts;
                ts = packet->trace->format->get_timespec(packet);
                return ((((uint64_t)ts.tv_sec) << 32) +
                                (((uint64_t)ts.tv_nsec << 32)/1000000000));
        } else if (packet->trace->format->get_timeval) {
                /* timeval -> timestamp */
                struct timeval tv;
                tv = packet->trace->format->get_timeval(packet);
                return ((((uint64_t)tv.tv_sec) << 32) +
                                (((uint64_t)tv.tv_usec << 32)/1000000));
        } else if (packet->trace->format->get_seconds) {
                /* seconds -> timestamp */
                double seconds = packet->trace->format->get_seconds(packet);
                return (((uint64_t)seconds)<<32)
                          + (uint64_t)((seconds-(uint64_t)seconds)*UINT_MAX);
        }
        else {
                return (uint64_t)0;
        }
                      
}

/* Get the current time in struct timeval
 * @param packet        a pointer to a libtrace_packet structure
 *
 * @returns time that this packet was seen in a struct timeval
 * @author Daniel Lawson
 * @author Perry Lorier
 */ 
DLLEXPORT struct timeval trace_get_timeval(const libtrace_packet_t *packet) {
        struct timeval tv;
        uint64_t ts = 0;
        if (packet->trace->format->get_timeval) {
                /* timeval -> timeval */
                tv = packet->trace->format->get_timeval(packet);
        } else if (packet->trace->format->get_erf_timestamp) {
                /* timestamp -> timeval */
                ts = packet->trace->format->get_erf_timestamp(packet);
#if __BYTE_ORDER == __BIG_ENDIAN
                tv.tv_sec = ts & 0xFFFFFFFF;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
                tv.tv_sec = ts >> 32;
#else
#error "What on earth are you running this on?"
#endif
                tv.tv_usec = ((ts&0xFFFFFFFF)*1000000)>>32;
                if (tv.tv_usec >= 1000000) {
                        tv.tv_usec -= 1000000;
                        tv.tv_sec += 1;
                }
        } else if (packet->trace->format->get_timespec) {
                struct timespec ts = packet->trace->format->get_timespec(packet);
                tv.tv_sec = ts.tv_sec;
                tv.tv_usec = ts.tv_nsec/1000;
        } else if (packet->trace->format->get_seconds) {
                /* seconds -> timeval */
                double seconds = packet->trace->format->get_seconds(packet);
                tv.tv_sec = (uint32_t)seconds;
                tv.tv_usec = (uint32_t)(((seconds - tv.tv_sec) * 1000000)/UINT_MAX);
        }
        else {
                tv.tv_sec=-1;
                tv.tv_usec=-1;
        }

        return tv;
}

DLLEXPORT struct timespec trace_get_timespec(const libtrace_packet_t *packet) {
        struct timespec ts;

        if (packet->trace->format->get_timespec) {
                return packet->trace->format->get_timespec(packet);
        } else if (packet->trace->format->get_erf_timestamp) {
                /* timestamp -> timeval */
                uint64_t erfts = packet->trace->format->get_erf_timestamp(packet);
#if __BYTE_ORDER == __BIG_ENDIAN
                ts.tv_sec = erfts & 0xFFFFFFFF;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
                ts.tv_sec = erfts >> 32;
#else
#error "What on earth are you running this on?"
#endif
                ts.tv_nsec = ((erfts&0xFFFFFFFF)*1000000000)>>32;
                if (ts.tv_nsec >= 1000000000) {
                        ts.tv_nsec -= 1000000000;
                        ts.tv_sec += 1;
                }
                return ts;
        } else if (packet->trace->format->get_timeval) {
                /* timeval -> timespec */
                struct timeval tv = packet->trace->format->get_timeval(packet);
                ts.tv_sec = tv.tv_sec;
                ts.tv_nsec = tv.tv_usec*1000;
                return ts;
        } else if (packet->trace->format->get_seconds) {
                /* seconds -> timespec */
                double seconds = packet->trace->format->get_seconds(packet);
                ts.tv_sec = (uint32_t)seconds;
                ts.tv_nsec = (long)(((seconds - ts.tv_sec) * 1000000000)/UINT_MAX);
                return ts;
        }
        else {
                ts.tv_sec=-1;
                ts.tv_nsec=-1;
                return ts;
        }
}


/* Get the current time in floating point seconds
 * @param packet        a pointer to a libtrace_packet structure
 * @returns time that this packet was seen in 64bit floating point seconds
 */ 
DLLEXPORT double trace_get_seconds(const libtrace_packet_t *packet) {
        double seconds = 0.0;

        if (packet->trace->format->get_seconds) {
                /* seconds->seconds */
                seconds = packet->trace->format->get_seconds(packet);
        } else if (packet->trace->format->get_erf_timestamp) {
                /* timestamp -> seconds */
                uint64_t ts = 0;
                ts = packet->trace->format->get_erf_timestamp(packet);
                seconds =  (ts>>32) + ((ts & UINT_MAX)*1.0 / UINT_MAX);
        } else if (packet->trace->format->get_timespec) {
                /* timespec -> seconds */
                struct timespec ts;
                ts = packet->trace->format->get_timespec(packet);
                seconds = ts.tv_sec + ((ts.tv_nsec * 1.0) / 1000000000);
        } else if (packet->trace->format->get_timeval) {
                /* timeval -> seconds */
                struct timeval tv;
                tv = packet->trace->format->get_timeval(packet);
                seconds = tv.tv_sec + ((tv.tv_usec * 1.0) / 1000000);
        }

        return seconds;
}

DLLEXPORT size_t trace_get_capture_length(const libtrace_packet_t *packet) 
{
        /* Cache the capture length */
        if (packet->capture_length == -1) {
                if (!packet->trace->format->get_capture_length)
                        return ~0U;
                /* Cast away constness because this is "just" a cache */
                ((libtrace_packet_t*)packet)->capture_length = 
                        packet->trace->format->get_capture_length(packet);
        }

        assert(packet->capture_length < LIBTRACE_PACKET_BUFSIZE);

        return packet->capture_length;
}
        
/* Get the size of the packet as it was seen on the wire.
 * @param packet        a pointer to a libtrace_packet structure
 *
 * @returns the size of the packet as it was on the wire.
 * @note Due to the trace being a header capture, or anonymisation this may
 * not be the same as the Capture Len.
 */ 
DLLEXPORT size_t trace_get_wire_length(const libtrace_packet_t *packet){
        if (packet->trace->format->get_wire_length) {
                return packet->trace->format->get_wire_length(packet);
        }
        return ~0U;

}

/* Get the length of the capture framing headers.
 * @param packet        the packet opaque pointer
 * @returns the size of the packet as it was on the wire.
 * @note this length corresponds to the difference between the size of a 
 * captured packet in memory, and the captured length of the packet
 */ 
DLLEXPORT SIMPLE_FUNCTION
size_t trace_get_framing_length(const libtrace_packet_t *packet) {
        if (packet->trace->format->get_framing_length) {
                return packet->trace->format->get_framing_length(packet);
        }
        return ~0U;
}


/* Get the type of the link layer
 * @param packet        a pointer to a libtrace_packet structure
 * @returns libtrace_linktype_t
 */
DLLEXPORT libtrace_linktype_t trace_get_link_type(const libtrace_packet_t *packet ) {
        if (packet->trace->format->get_link_type) {
                return packet->trace->format->get_link_type(packet);
        }
        return (libtrace_linktype_t)-1;
}

/* process a libtrace event
 * @param trace the libtrace opaque pointer
 * @param packet the libtrace_packet opaque pointer
 * @returns
 *  TRACE_EVENT_IOWAIT  Waiting on I/O on fd
 *  TRACE_EVENT_SLEEP   Next event in seconds
 *  TRACE_EVENT_PACKET  Packet arrived in buffer with size size
 *  TRACE_EVENT_TERMINATE Trace terminated (perhaps with an error condition)
 * FIXME currently keeps a copy of the packet inside the trace pointer,
 * which in turn is stored inside the new packet object...
 */
DLLEXPORT libtrace_eventobj_t trace_event(libtrace_t *trace, 
                libtrace_packet_t *packet) {
        libtrace_eventobj_t event = {TRACE_EVENT_IOWAIT,0,0.0,0};

        if (!trace) {
                fprintf(stderr,"You called trace_event() with a NULL trace object!\n");
        }
        assert(trace);
        assert(packet);

        /* Clear the packet cache */
        packet->capture_length = -1;
        packet->l3_header = NULL;
        packet->l3_ethertype = 0;
        
        /* Store the trace we are reading from into the packet opaque
         * structure */
        packet->trace = trace;

        if (packet->trace->format->trace_event) {
                event=packet->trace->format->trace_event(trace,packet);
                if (event.type == TRACE_EVENT_PACKET) {
                        ++trace->accepted_packets;
                }
        }
        return event;

}

/** Setup a BPF filter based on pre-compiled byte-code.
 * @param bf_insns      A pointer to the start of the byte-code
 * @param bf_len        The number of BPF instructions
 * @returns             an opaque pointer to a libtrace_filter_t object
 * @note                The supplied byte-code is not checked for correctness.
 * @author              Scott Raynel
 */
DLLEXPORT libtrace_filter_t *
trace_create_filter_from_bytecode(void *bf_insns, unsigned int bf_len)
{
#ifndef HAVE_BPF_FILTER
        fprintf(stderr, "This version of libtrace does not have BPF support\n");
        return NULL;
#else
        struct libtrace_filter_t *filter = (struct libtrace_filter_t *)
                malloc(sizeof(struct libtrace_filter_t));
        filter->filter.bf_insns = (struct bpf_insn *)
                malloc(sizeof(struct bpf_insn) * bf_len);
        
        memcpy(filter->filter.bf_insns, bf_insns,
                        bf_len * sizeof(struct bpf_insn));
        
        filter->filter.bf_len = bf_len;
        filter->filterstring = NULL;
        filter->jitfilter = NULL;
        /* "flag" indicates that the filter member is valid */
        filter->flag = 1; 
        
        return filter;
#endif
}

/* Create a BPF filter
 * @param filterstring a char * containing the bpf filter string
 * @returns opaque pointer pointer to a libtrace_filter_t object
 */
DLLEXPORT libtrace_filter_t *trace_create_filter(const char *filterstring) {
#ifdef HAVE_BPF_FILTER
        libtrace_filter_t *filter = (libtrace_filter_t*)
                                malloc(sizeof(libtrace_filter_t));
        filter->filterstring = strdup(filterstring);
        filter->jitfilter = NULL;
        filter->flag = 0;
        return filter;
#else
        fprintf(stderr,"This version of libtrace does not have bpf filter support\n");
        return NULL;
#endif
}

DLLEXPORT void trace_destroy_filter(libtrace_filter_t *filter)
{
#ifdef HAVE_BPF_FILTER
        free(filter->filterstring);
        if (filter->flag)
                pcap_freecode(&filter->filter);
#ifdef HAVE_LLVM
        if (filter->jitfilter) 
                destroy_program(filter->jitfilter);
#endif
        free(filter);
#else

#endif
}

/* Compile a bpf filter, now we know the link type for the trace that we're
 * applying it to.
 *
 * @internal
 *
 * @returns -1 on error, 0 on success
 */
static int trace_bpf_compile(libtrace_filter_t *filter,
                const libtrace_packet_t *packet ) {
#ifdef HAVE_BPF_FILTER
        void *linkptr = 0;
        libtrace_linktype_t linktype;
        assert(filter);

        /* If this isn't a real packet, then fail */
        linkptr = trace_get_packet_buffer(packet,&linktype,NULL);
        if (!linkptr) {
                trace_set_err(packet->trace,
                                TRACE_ERR_BAD_PACKET,"Packet has no payload");
                return -1;
        }
        
        if (filter->filterstring && ! filter->flag) {
                pcap_t *pcap = NULL;
                if (linktype==(libtrace_linktype_t)-1) {
                        trace_set_err(packet->trace,
                                        TRACE_ERR_BAD_PACKET,
                                        "Packet has an unknown linktype");
                        return -1;
                }
                if (libtrace_to_pcap_dlt(linktype) == ~1U) {
                        trace_set_err(packet->trace,TRACE_ERR_BAD_PACKET,
                                        "Unknown pcap equivalent linktype");
                        return -1;
                }
                pcap=(pcap_t *)pcap_open_dead(
                                (int)libtrace_to_pcap_dlt(linktype),
                                1500U);
                /* build filter */
                assert(pcap);
                if (pcap_compile( pcap, &filter->filter, filter->filterstring, 
                                        1, 0)) {
                        trace_set_err(packet->trace,TRACE_ERR_BAD_PACKET,
                                        "Unable to compile the filter \"%s\": %s", 
                                        filter->filterstring,
                                        pcap_geterr(pcap));
                        pcap_close(pcap);
                        return -1;
                }
                pcap_close(pcap);
                filter->flag=1;
        }
        return 0;
#else
        assert(!"Internal bug: This should never be called when BPF not enabled");
        trace_set_err(packet->trace,TRACE_ERR_OPTION_UNAVAIL,
                                "Feature unavailable");
        return -1;
#endif
}

DLLEXPORT int trace_apply_filter(libtrace_filter_t *filter,
                        const libtrace_packet_t *packet) {
#ifdef HAVE_BPF_FILTER
        void *linkptr = 0;
        uint32_t clen = 0;
        bool free_packet_needed = false;
        int ret;
        libtrace_packet_t *packet_copy = (libtrace_packet_t*)packet;

        assert(filter);
        assert(packet);

        if (libtrace_to_pcap_dlt(trace_get_link_type(packet))==~0U) {
                
                /* If we cannot get a suitable DLT for the packet, it may
                 * be because the packet is encapsulated in a link type that
                 * does not correspond to a DLT. Therefore, we should try
                 * popping off headers until we either can find a suitable
                 * link type or we can't do any more sensible decapsulation. */
                
                /* Copy the packet, as we don't want to trash the one we
                 * were passed in */
                packet_copy=trace_copy_packet(packet);
                free_packet_needed=true;

                while (libtrace_to_pcap_dlt(trace_get_link_type(packet_copy))==
                                ~0U) {
                        if (!demote_packet(packet_copy)) {
                                trace_set_err(packet->trace, 
                                                TRACE_ERR_NO_CONVERSION,
                                                "pcap does not support this format");
                                if (free_packet_needed) {
                                        trace_destroy_packet(packet_copy);
                                }
                                return -1;
                        }
                }
        }
        
        linkptr = trace_get_packet_buffer(packet_copy,NULL,&clen);
        if (!linkptr) {
                if (free_packet_needed) {
                        trace_destroy_packet(packet_copy);
                }
                return 0;
        }

        /* We need to compile the filter now, because before we didn't know 
         * what the link type was
         */
        if (trace_bpf_compile(filter,packet_copy)==-1) {
                if (free_packet_needed) {
                        trace_destroy_packet(packet_copy);
                }
                return -1;
        }

        /* If we're jitting, we may need to JIT the BPF code now too */
#if HAVE_LLVM
        if (!filter->jitfilter) {
                filter->jitfilter = compile_program(filter->filter.bf_insns, filter->filter.bf_len);
        }
#endif

        assert(filter->flag);
        /* Now execute the filter */
#if HAVE_LLVM
        ret=filter->jitfilter->bpf_run((unsigned char *)linkptr, clen);
#else
        ret=bpf_filter(filter->filter.bf_insns,(u_char*)linkptr,(unsigned int)clen,(unsigned int)clen);
#endif

        /* If we copied the packet earlier, make sure that we free it */
        if (free_packet_needed) {
                trace_destroy_packet(packet_copy);
        }
        return ret;
#else
        fprintf(stderr,"This version of libtrace does not have bpf filter support\n");
        return 0;
#endif
}

/* Set the direction flag, if it has one
 * @param packet the packet opaque pointer
 * @param direction the new direction (0,1,2,3)
 * @returns a signed value containing the direction flag, or -1 if this is not supported
 */
DLLEXPORT libtrace_direction_t trace_set_direction(libtrace_packet_t *packet, 
                libtrace_direction_t direction) 
{
        assert(packet);
        if (packet->trace->format->set_direction) {
                return packet->trace->format->set_direction(packet,direction);
        }
        return (libtrace_direction_t)~0U;
}

/* Get the direction flag, if it has one
 * @param packet a pointer to a libtrace_packet structure
 * @returns a signed value containing the direction flag, or -1 if this is not supported
 * The direction is defined as 0 for packets originating locally (ie, outbound)
 * and 1 for packets originating remotely (ie, inbound).
 * Other values are possible, which might be overloaded to mean special things
 * for a special trace.
 */
DLLEXPORT libtrace_direction_t trace_get_direction(const libtrace_packet_t *packet) 
{
        assert(packet);
        if (packet->trace->format->get_direction) {
                return packet->trace->format->get_direction(packet);
        }
        return (libtrace_direction_t)~0U;
}

#define ROOT_SERVER(x) ((x) < 512)
#define ROOT_CLIENT(x) ((512 <= (x)) && ((x) < 1024))
#define NONROOT_SERVER(x) ((x) >= 5000)
#define NONROOT_CLIENT(x) ((1024 <= (x)) && ((x) < 5000))
#define DYNAMIC(x) ((49152 < (x)) && ((x) < 65535))
#define SERVER(x) ROOT_SERVER(x) || NONROOT_SERVER(x)
#define CLIENT(x) ROOT_CLIENT(x) || NONROOT_CLIENT(x) 

/* Attempt to deduce the 'server' port
 * @param protocol the IP protocol (eg, 6 or 17 for TCP or UDP)
 * @param source the TCP or UDP source port
 * @param dest the TCP or UDP destination port
 * @returns a hint as to which port is the server port
 */
DLLEXPORT int8_t trace_get_server_port(UNUSED uint8_t protocol, 
                uint16_t source, uint16_t dest) 
{
        /*
         * * If the ports are equal, return DEST
         * * Check for well-known ports in the given protocol
         * * Root server ports: 0 - 511
         * * Root client ports: 512 - 1023
         * * non-root client ports: 1024 - 4999
         * * non-root server ports: 5000+
         * * Check for static ranges: 1024 - 49151
         * * Check for dynamic ranges: 49152 - 65535
         * * flip a coin.
         */
        
        /* equal */
        if (source == dest)
                return USE_DEST;

        /* root server port, 0 - 511 */
        if (ROOT_SERVER(source) && ROOT_SERVER(dest)) {
                if (source < dest)
                        return USE_SOURCE;
                return USE_DEST;
        }

        if (ROOT_SERVER(source) && !ROOT_SERVER(dest))
                return USE_SOURCE;
        if (!ROOT_SERVER(source) && ROOT_SERVER(dest))
                return USE_DEST;

        /* non-root server */
        if (NONROOT_SERVER(source) && NONROOT_SERVER(dest)) {
                if (source < dest)
                        return USE_SOURCE;
                return USE_DEST;
        }
        if (NONROOT_SERVER(source) && !NONROOT_SERVER(dest))
                return USE_SOURCE;
        if (!NONROOT_SERVER(source) && NONROOT_SERVER(dest))
                return USE_DEST;

        /* root client */
        if (ROOT_CLIENT(source) && ROOT_CLIENT(dest)) {
                if (source < dest)
                        return USE_SOURCE;
                return USE_DEST;
        }
        if (ROOT_CLIENT(source) && !ROOT_CLIENT(dest)) {
                /* prefer root-client over nonroot-client */
                if (NONROOT_CLIENT(dest))
                        return USE_SOURCE;
                return USE_DEST;
        }
        if (!ROOT_CLIENT(source) && ROOT_CLIENT(dest)) {
                /* prefer root-client over nonroot-client */
                if (NONROOT_CLIENT(source))
                        return USE_DEST;
                return USE_SOURCE;
        }
        
        /* nonroot client */
        if (NONROOT_CLIENT(source) && NONROOT_CLIENT(dest)) {
                if (source < dest) 
                        return USE_SOURCE;
                return USE_DEST;
        }
        if (NONROOT_CLIENT(source) && !NONROOT_CLIENT(dest))
                return USE_DEST;
        if (!NONROOT_CLIENT(source) && NONROOT_CLIENT(dest))
                return USE_SOURCE;

        /* dynamic range */
        if (DYNAMIC(source) && DYNAMIC(dest)) {
                if (source < dest)
                        return USE_SOURCE;
                return USE_DEST;
        }
        if (DYNAMIC(source) && !DYNAMIC(dest))
                return USE_DEST;
        if (!DYNAMIC(source) && DYNAMIC(dest))
                return USE_SOURCE;
        /*
        if (SERVER(source) && CLIENT(dest)) 
                return USE_SOURCE;
        
        if (SERVER(dest) && CLIENT(source)) 
                return USE_DEST;
        if (ROOT_SERVER(source) && !ROOT_SERVER(dest)) 
                return USE_SOURCE;
        if (ROOT_SERVER(dest) && !ROOT_SERVER(source)) 
                return USE_DEST;
        */
        /* failing that test... */
        if (source < dest) {
                return USE_SOURCE;
        } 
        return USE_DEST;
        
}

/* Truncate the packet at the suggested length
 * @param packet        the packet opaque pointer
 * @param size          the new length of the packet
 * @returns the new size of the packet
 * @note size and the return size refer to the network-level payload of the
 * packet, and do not include any capture headers. For example, to truncate a
 * packet after the IP header, set size to sizeof(ethernet_header) +
 * sizeof(ip_header)
 * @note If the original network-level payload is smaller than size, then the
 * original size is returned and the packet is left unchanged.
 */
DLLEXPORT size_t trace_set_capture_length(libtrace_packet_t *packet, size_t size) {
        assert(packet);

        if (packet->trace->format->set_capture_length) {
                return packet->trace->format->set_capture_length(packet,size);
        }

        return ~0U;
}

/* Splits a URI into two components - the format component which is seen before
 * the ':', and the uridata which follows the ':'.
 *
 * Returns a pointer to the URI data, but updates the format parameter to
 * point to a copy of the format component. 
 */

DLLEXPORT const char * trace_parse_uri(const char *uri, char **format) {
        const char *uridata = 0;
        
        if((uridata = strchr(uri,':')) == NULL) {
                /* Badly formed URI - needs a : */
                return 0;
        }

        if ((unsigned)(uridata - uri) > URI_PROTO_LINE) {
                /* Badly formed URI - uri type is too long */
                return 0;
        }

        /* NOTE: this is allocated memory - it should be freed by the caller
         * once they are done with it */
        *format=xstrndup(uri, (size_t)(uridata - uri));

        /* Push uridata past the delimiter */
        uridata++;
        
        return uridata;
}

enum base_format_t trace_get_format(libtrace_packet_t *packet) 
{
        assert(packet);

        return packet->trace->format->type;
}
        
DLLEXPORT libtrace_err_t trace_get_err(libtrace_t *trace)
{
        libtrace_err_t err = trace->err;
        trace->err.err_num = 0; /* "OK" */
        trace->err.problem[0]='\0';
        return err;
}

DLLEXPORT bool trace_is_err(libtrace_t *trace)
{
        return trace->err.err_num != 0;
}

/* Prints the input error status to standard error and clears the error state */
DLLEXPORT void trace_perror(libtrace_t *trace,const char *msg,...)
{
        char buf[256];
        va_list va;
        va_start(va,msg);
        vsnprintf(buf,sizeof(buf),msg,va);
        va_end(va);
        if(trace->err.err_num) {
                if (trace->uridata) {
                        fprintf(stderr,"%s(%s): %s\n",
                                        buf,trace->uridata,trace->err.problem);
                } else {
                        fprintf(stderr,"%s: %s\n", buf, trace->err.problem);
                }
        } else {
                if (trace->uridata) {
                        fprintf(stderr,"%s(%s): No error\n",buf,trace->uridata);
                } else {
                        fprintf(stderr,"%s: No error\n", buf);
                }
        }
        trace->err.err_num = 0; /* "OK" */
        trace->err.problem[0]='\0';
}

DLLEXPORT libtrace_err_t trace_get_err_output(libtrace_out_t *trace)
{
        libtrace_err_t err = trace->err;
        trace->err.err_num = TRACE_ERR_NOERROR; /* "OK" */
        trace->err.problem[0]='\0';
        return err;
}

DLLEXPORT bool trace_is_err_output(libtrace_out_t *trace)
{
        return trace->err.err_num != 0;
}

/* Prints the output error status to standard error and clears the error state
 */
DLLEXPORT void trace_perror_output(libtrace_out_t *trace,const char *msg,...)
{
        char buf[256];
        va_list va;
        va_start(va,msg);
        vsnprintf(buf,sizeof(buf),msg,va);
        va_end(va);
        if(trace->err.err_num) {
                fprintf(stderr,"%s(%s): %s\n",
                                buf,
                                trace->uridata?trace->uridata:"no uri",
                                trace->err.problem);
        } else {
                fprintf(stderr,"%s(%s): No error\n",buf,trace->uridata);
        }
        trace->err.err_num = TRACE_ERR_NOERROR; /* "OK" */
        trace->err.problem[0]='\0';
}

DLLEXPORT int trace_seek_erf_timestamp(libtrace_t *trace, uint64_t ts)
{
        if (trace->format->seek_erf) {
                return trace->format->seek_erf(trace,ts);
        }
        else {
                if (trace->format->seek_timeval) {
                        struct timeval tv;
#if __BYTE_ORDER == __BIG_ENDIAN
                        tv.tv_sec = ts & 0xFFFFFFFF;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
                        tv.tv_sec = ts >> 32;
#else
#error "What on earth are you running this on?"
#endif
                        tv.tv_usec = ((ts&0xFFFFFFFF)*1000000)>>32;
                        if (tv.tv_usec >= 1000000) {
                                tv.tv_usec -= 1000000;
                                tv.tv_sec += 1;
                        }
                        return trace->format->seek_timeval(trace,tv);
                }
                if (trace->format->seek_seconds) {
                        double seconds =  
                                (ts>>32) + ((ts & UINT_MAX)*1.0 / UINT_MAX);
                        return trace->format->seek_seconds(trace,seconds);
                }
                trace_set_err(trace,
                                TRACE_ERR_OPTION_UNAVAIL,
                                "Feature unimplemented");
                return -1;
        }
}

DLLEXPORT int trace_seek_seconds(libtrace_t *trace, double seconds)
{
        if (trace->format->seek_seconds) {
                return trace->format->seek_seconds(trace,seconds);
        }
        else {
                if (trace->format->seek_timeval) {
                        struct timeval tv;
                        tv.tv_sec = (uint32_t)seconds;
                        tv.tv_usec = (uint32_t)(((seconds - tv.tv_sec) * 1000000)/UINT_MAX);
                        return trace->format->seek_timeval(trace,tv);
                }
                if (trace->format->seek_erf) {
                        uint64_t timestamp = 
                                ((uint64_t)((uint32_t)seconds) << 32) + \
                            (uint64_t)(( seconds - (uint32_t)seconds   ) * UINT_MAX);
                        return trace->format->seek_erf(trace,timestamp);
                }
                trace_set_err(trace,
                                TRACE_ERR_OPTION_UNAVAIL,
                                "Feature unimplemented");
                return -1;
        }
}

DLLEXPORT int trace_seek_timeval(libtrace_t *trace, struct timeval tv)
{
        if (trace->format->seek_timeval) {
                return trace->format->seek_timeval(trace,tv);
        }
        else {
                if (trace->format->seek_erf) {
                        uint64_t timestamp = ((((uint64_t)tv.tv_sec) << 32) + \
                                (((uint64_t)tv.tv_usec * UINT_MAX)/1000000));
                        return trace->format->seek_erf(trace,timestamp);
                }
                if (trace->format->seek_seconds) {
                        double seconds = tv.tv_sec + ((tv.tv_usec * 1.0)/1000000);
                        return trace->format->seek_seconds(trace,seconds);
                }
                trace_set_err(trace,
                                TRACE_ERR_OPTION_UNAVAIL,
                                "Feature unimplemented");
                return -1;
        }
}

/* Converts a binary ethernet MAC address into a printable string */
DLLEXPORT char *trace_ether_ntoa(const uint8_t *addr, char *buf)
{
        static char staticbuf[18]={0,};
        if (!buf)
                buf=staticbuf;
        snprintf(buf,(size_t)18,"%02x:%02x:%02x:%02x:%02x:%02x",
                        addr[0],addr[1],addr[2],
                        addr[3],addr[4],addr[5]);
        return buf;
}

/* Converts a printable ethernet MAC address into a binary format */
DLLEXPORT uint8_t *trace_ether_aton(const char *buf, uint8_t *addr)
{
        uint8_t *buf2 = addr;
        unsigned int tmp[6];
        static uint8_t staticaddr[6];
        if (!buf2)
                buf2=staticaddr;
        sscanf(buf,"%x:%x:%x:%x:%x:%x",
                        &tmp[0],&tmp[1],&tmp[2],
                        &tmp[3],&tmp[4],&tmp[5]);
        buf2[0]=tmp[0]; buf2[1]=tmp[1]; buf2[2]=tmp[2];
        buf2[3]=tmp[3]; buf2[4]=tmp[4]; buf2[5]=tmp[5];
        return buf2;
}


/* Creates a libtrace packet from scratch using the contents of the provided 
 * buffer as the packet payload.
 *
 * Unlike trace_prepare_packet(), the buffer should not contain any capture
 * format headers; instead this function will add the PCAP header to the 
 * packet record. This also means only PCAP packets can be constructed using
 * this function.
 *
 */
DLLEXPORT
void trace_construct_packet(libtrace_packet_t *packet,
                libtrace_linktype_t linktype,
                const void *data,
                uint16_t len)
{
        size_t size;
        static libtrace_t *deadtrace=NULL;
        libtrace_pcapfile_pkt_hdr_t hdr;
#ifdef WIN32
        struct _timeb tstruct;
#else
        struct timeval tv;
#endif

        /* We need a trace to attach the constructed packet to (and it needs
         * to be PCAP) */
        if (NULL == deadtrace) 
                deadtrace=trace_create_dead("pcapfile");

        /* Fill in the new PCAP header */
#ifdef WIN32
        _ftime(&tstruct);
        hdr.ts_sec=tstruct.time;
        hdr.ts_usec=tstruct.millitm * 1000;
#else
        gettimeofday(&tv,NULL);
        hdr.ts_sec=tv.tv_sec;
        hdr.ts_usec=tv.tv_usec;
#endif

        hdr.caplen=len;
        hdr.wirelen=len;

        /* Now fill in the libtrace packet itself */
        packet->trace=deadtrace;
        size=len+sizeof(hdr);
        if (packet->buf_control==TRACE_CTRL_PACKET) {
                packet->buffer=realloc(packet->buffer,size);
        }
        else {
                packet->buffer=malloc(size);
        }
        packet->buf_control=TRACE_CTRL_PACKET;
        packet->header=packet->buffer;
        packet->payload=(void*)((char*)packet->buffer+sizeof(hdr));
        
        /* Ugh, memcpy - sadly necessary */
        memcpy(packet->header,&hdr,sizeof(hdr));
        memcpy(packet->payload,data,(size_t)len);
        packet->type=pcap_linktype_to_rt(libtrace_to_pcap_linktype(linktype));
}


uint64_t trace_get_received_packets(libtrace_t *trace)
{
        assert(trace);
        if (trace->format->get_received_packets) {
                return trace->format->get_received_packets(trace);
        }
        return (uint64_t)-1;
}

uint64_t trace_get_filtered_packets(libtrace_t *trace)
{
        assert(trace);
        if (trace->format->get_filtered_packets) {
                return trace->format->get_filtered_packets(trace)+
                        trace->filtered_packets;
        }
        if (trace->format->get_received_packets
                && trace->format->get_dropped_packets) {
                return 
                        ((trace_get_received_packets(trace)
                        -trace_get_accepted_packets(trace))
                        -trace_get_dropped_packets(trace))
                        +trace->filtered_packets;
        }
        return trace->filtered_packets;
}

uint64_t trace_get_dropped_packets(libtrace_t *trace)
{
        assert(trace);
        if (trace->format->get_dropped_packets) {
                return trace->format->get_dropped_packets(trace);
        }
        return (uint64_t)-1;
}

uint64_t trace_get_accepted_packets(libtrace_t *trace)
{
        assert(trace);
        return trace->accepted_packets;
}

void register_format(struct libtrace_format_t *f) {
        assert(f->next==NULL); /* Can't register a format twice */
        f->next=formats_list;
        formats_list=f;

        /* Now, verify that the format has at least the minimum functionality.
         * 
         * This #if can be changed to a 1 to output warnings about inconsistent
         * functions being provided by format modules.  This generally is very
         * noisy, as almost all modules don't implement one or more functions
         * for various reasons.  This is very useful when checking a new 
         * format module is sane.
         */ 
#if 0
        if (f->init_input) {
#define REQUIRE(x) \
                if (!f->x) \
                        fprintf(stderr,"%s: Input format should provide " #x "\n",f->name)
                REQUIRE(read_packet);
                REQUIRE(start_input);
                REQUIRE(fin_input);
                REQUIRE(get_link_type);
                REQUIRE(get_capture_length);
                REQUIRE(get_wire_length);
                REQUIRE(get_framing_length);
                REQUIRE(trace_event);
                if (!f->get_erf_timestamp 
                        && !f->get_seconds
                        && !f->get_timeval) {
                        fprintf(stderr,"%s: A trace format capable of input, should provide at least one of\n"
"get_erf_timestamp, get_seconds or trace_timeval\n",f->name);
                }
                if (f->trace_event!=trace_event_trace) {
                        /* Theres nothing that a trace file could optimise with
                         * config_input
                         */
                        REQUIRE(pause_input);
                        REQUIRE(config_input);
                        REQUIRE(get_fd);
                }
                else {
                        if (f->get_fd) {
                                fprintf(stderr,"%s: Unnecessary get_fd\n",
                                                f->name);
                        }
                }
#undef REQUIRE
        }
        else {
#define REQUIRE(x) \
                if (f->x) \
                        fprintf(stderr,"%s: Non Input format shouldn't need " #x "\n",f->name)
                REQUIRE(read_packet);
                REQUIRE(start_input);
                REQUIRE(pause_input);
                REQUIRE(fin_input);
                REQUIRE(get_link_type);
                REQUIRE(get_capture_length);
                REQUIRE(get_wire_length);
                REQUIRE(get_framing_length);
                REQUIRE(trace_event);
                REQUIRE(get_seconds);
                REQUIRE(get_timeval);
                REQUIRE(get_erf_timestamp);
#undef REQUIRE
        }
        if (f->init_output) {
#define REQUIRE(x) \
                if (!f->x) \
                        fprintf(stderr,"%s: Output format should provide " #x "\n",f->name)
                REQUIRE(write_packet);
                REQUIRE(start_output);
                REQUIRE(config_output);
                REQUIRE(fin_output);
#undef REQUIRE
        }
        else {
#define REQUIRE(x) \
                if (f->x) \
                        fprintf(stderr,"%s: Non Output format shouldn't need " #x "\n",f->name)
                REQUIRE(write_packet);
                REQUIRE(start_output);
                REQUIRE(config_output);
                REQUIRE(fin_output);
#undef REQUIRE
        }
#endif
}