source: lib/libtrace.h @ d3b2234

/*
 * This file is part of libtrace
 *
 * Copyright (c) 2004 The University of Waikato, Hamilton, New Zealand.
 * Authors: Daniel Lawson 
 *          Perry Lorier 
 *          
 * 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
 *
 * $Id$
 *
 */

#ifndef LIBTRACE_H
#define LIBTRACE_H

/** @file
 *
 * @brief Trace file processing library header
 *
 * @author Daniel Lawson
 * @author Perry Lorier
 *
 * @version $Id$
 *
 * This library provides a per packet interface into a trace file, or a live 
 * captures.  It supports ERF, DAG cards, WAG cards, WAG's event format,
 * pcap etc.
 *
 * @par Usage
 * See the example/ directory in the source distribution for some simple examples
 * @par Linking
 * To use this library you need to link against libtrace by passing -ltrace
 * to your linker. You may also need to link against a version of libpcap 
 * and of zlib which are compiled for largefile support (if you wish to access
 * traces larger than 2 GB). This is left as an exercise for the reader. Debian
 * Woody, at least, does not support large file offsets.
 *
 */

#include <sys/types.h>
#include <netinet/in.h>
/** API version as 2 byte hex digits, eg 0xXXYYZZ */
#define LIBTRACE_API_VERSION 0x030000  /* 3.0.00 */

#ifdef __cplusplus 
extern "C" { 
#endif

/* Function does not depend on anything but its
 * parameters, used to hint gcc's optimisations
 */
#if __GNUC__ >= 3 
#  define SIMPLE_FUNCTION __attribute__((pure))
#  define UNUSED __attribute__((unused))
#  define PACKED __attribute__((packed))
#else
#  define SIMPLE_FUNCTION
#  define UNUSED
#endif
        
/** Opaque structure holding information about an output trace */
typedef struct libtrace_out_t libtrace_out_t;
        
/** Opaque structure holding information about a trace */
typedef struct libtrace_t libtrace_t;
        
/** Opaque structure holding information about a bpf filter */
typedef struct libtrace_filter_t libtrace_filter_t;

/* the letters p and e are magic numbers used to detect if the packet
 * wasn't created properly
 */
typedef enum {TRACE_CTRL_PACKET='p', TRACE_CTRL_EXTERNAL='e' } buf_control_t;
/** Structure holding information about a packet */
#define LIBTRACE_PACKET_BUFSIZE 65536

/** The libtrace structure, applications shouldn't be meddling around in here 
 */
typedef struct libtrace_packet_t {
        struct libtrace_t *trace;
        void *header;
        void *payload;
        buf_control_t buf_control; 
        void *buffer;
        size_t size;            /**< trace_get_framing_length()
                                 * +trace_get_capture_length() */
        uint8_t type;           /**< rt protocol type for the packet */
} libtrace_packet_t;
                     

/** Enumeration of error codes */
enum {
        TRACE_ERR_NOERROR       = 0,
        TRACE_ERR_BAD_FORMAT    = -1,
        TRACE_ERR_NO_INIT       = -2,
        TRACE_ERR_NO_INIT_OUT   = -3,
        TRACE_ERR_URI_LONG      = -4,
        TRACE_ERR_URI_NOCOLON   = -5,
        TRACE_ERR_INIT_FAILED   = -6,
        TRACE_ERR_UNKNOWN_OPTION= -7,
        TRACE_ERR_NO_CONVERSION = -8,
        TRACE_ERR_BAD_PACKET    = -9,
        TRACE_ERR_OPTION_UNAVAIL= -10
};

/** @name Protocol structures
 * These convenience structures are here as they are portable ways of dealing
 * with various protocols.
 * @{
 */

/** Structure for dealing with IP packets */
typedef PACKED struct libtrace_ip
{
#if BYTE_ORDER == LITTLE_ENDIAN
    unsigned int ip_hl:4;               /**< header length */
    unsigned int ip_v:4;                /**< version */
#elif BYTE_ORDER == BIG_ENDIAN
    unsigned int ip_v:4;                /**< version */
    unsigned int ip_hl:4;               /**< header length */
#else
#   error "Adjust your <bits/endian.h> defines"
#endif
    u_int8_t ip_tos;                    /**< type of service */
    u_short ip_len;                     /**< total length */
    u_short ip_id;                      /**< identification */
#if BYTE_ORDER == LITTLE_ENDIAN
    unsigned int ip_off:12;             /**< fragment offset */
    unsigned int ip_mf:1;               /**< more fragments flag */
    unsigned int ip_df:1;               /**< dont fragment flag */
    unsigned int ip_rf:1;               /**< reserved fragment flag */
#elif BYTE_ORDER == BIG_ENDIAN
    unsigned int ip_rf:1;
    unsigned int ip_df:1;
    unsigned int ip_mf:1;
    unsigned int ip_off:12;
#else
#   error "Adjust your <bits/endian.h> defines"
#endif
    u_int8_t ip_ttl;                    /**< time to live */
    u_int8_t ip_p;                      /**< protocol */
    u_short ip_sum;                     /**< checksum */
    struct in_addr ip_src;              /**< source address */
    struct in_addr ip_dst;              /**< dest address */
} libtrace_ip_t
;

/** Structure for dealing with TCP packets */
typedef struct libtrace_tcp
  {
    u_int16_t source;           /**< Source Port */
    u_int16_t dest;             /**< Destination port */
    u_int32_t seq;              /**< Sequence number */
    u_int32_t ack_seq;          /**< Acknowledgement Number */
#  if BYTE_ORDER == LITTLE_ENDIAN
    unsigned int res1:4;        /**< Reserved bits */
    unsigned int doff:4;        /**< data offset */     
    unsigned int fin:1;         /**< FIN */
    unsigned int syn:1;         /**< SYN flag */
    unsigned int rst:1;         /**< RST flag */
    unsigned int psh:1;         /**< PuSH flag */
    unsigned int ack:1;         /**< ACK flag */
    unsigned int urg:1;         /**< URG flag */
    unsigned int res2:2;        /**< Reserved */
#  elif BYTE_ORDER == BIG_ENDIAN
    unsigned int doff:4;        /**< Data offset */
    unsigned int res1:4;        /**< Reserved bits */
    unsigned int res2:2;        /**< Reserved */
    unsigned int urg:1;         /**< URG flag */
    unsigned int ack:1;         /**< ACK flag */
    unsigned int psh:1;         /**< PuSH flag */
    unsigned int rst:1;         /**< RST flag */
    unsigned int syn:1;         /**< SYN flag */
    unsigned int fin:1;         /**< FIN flag */
#  else
#   error "Adjust your <bits/endian.h> defines"
#  endif
    u_int16_t window;           /**< Window Size */
    u_int16_t check;            /**< Checksum */
    u_int16_t urg_ptr;          /**< Urgent Pointer */
} __attribute__ ((packed)) libtrace_tcp_t;

/** UDP Header for dealing with UDP packets */
typedef struct libtrace_udp {
  u_int16_t     source;         /**< Source port */
  u_int16_t     dest;           /**< Destination port */
  u_int16_t     len;            /**< Length */
  u_int16_t     check;          /**< Checksum */
} __attribute__ ((packed)) libtrace_udp_t;

/** ICMP Header for dealing with icmp packets */
typedef struct libtrace_icmp
{
  u_int8_t type;                /**< message type */
  u_int8_t code;                /**< type sub-code */
  u_int16_t checksum;           /**< checksum */
  union
  {
    struct
    {
      u_int16_t id;
      u_int16_t sequence;
    } echo;                     /**< echo datagram */
    u_int32_t   gateway;        /**< gateway address */
    struct
    {
      u_int16_t unused;
      u_int16_t mtu;
    } frag;                     /**< path mtu discovery */
  } un;                         /**< Union for payloads of various icmp codes */
} __attribute__ ((packed)) libtrace_icmp_t;

/** LLC/SNAP header */
typedef struct libtrace_llcsnap
{
  u_int8_t dsap;
  u_int8_t ssap;
  u_int8_t control;
  u_int32_t oui:24;
  u_int16_t type;
} __attribute__ ((packed)) libtrace_llcsnap_t;

/** 802.3 frame */
typedef struct libtrace_ether
{
  u_int8_t ether_dhost[6];      /* destination ether addr */
  u_int8_t ether_shost[6];      /* source ether addr */
  u_int16_t ether_type;         /* packet type ID field (next-header) */
} __attribute__ ((packed)) libtrace_ether_t;

/** 802.1Q frame */
typedef struct libtrace_8021q 
{
  u_int8_t  ether_dhost[6];      /* destination eth addr */
  u_int8_t  ether_shost[6];      /* source ether addr    */
  u_int16_t ether_type;          /* packet type ID field , 0x8100 for VLAN */
  unsigned int vlan_pri:3;       /* vlan user priority */
  unsigned int vlan_cfi:1;       /* vlan format indicator, 0 for ethernet, 1 for token ring */
  unsigned int vlan_id:12;       /* vlan id */
  u_int16_t vlan_ether_type;     /* vlan sub-packet type ID field (next-header)*/
} __attribute__ ((packed)) libtrace_8021q_t;

/** ATM cell */
typedef struct libtrace_atm_cell
{
  unsigned int gfc:4;
  u_int8_t vpi;
  u_int16_t vci;
  unsigned int pt:3;
  unsigned int clp:1;
  unsigned int hec;
} __attribute__ ((packed)) libtrace_atm_cell;

/** POS header */
typedef struct libtrace_pos
{
 u_int16_t header;
 u_int16_t ether_type;
} __attribute__ ((packed)) libtrace_pos;
/*@}*/

/** 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
 */
void trace_help();

/** Gets the output format for a given output trace
 *
 * @param libtrace      the output trace to get the name of the format fo
 * @return callee-owned null-terminated char* containing the output format
 *
 */
SIMPLE_FUNCTION
char *trace_get_output_format(const libtrace_out_t *libtrace);

/** @name Trace management
 * These members deal with creating, configuring, starting, pausing and
 * cleaning up a trace object
 *@{
 */

/** Create a trace file from a URI
 * 
 * @param uri containing a valid libtrace URI
 * @return opaque pointer to a libtrace_t
 *
 * Valid URI's are:
 *  - erf:/path/to/erf/file
 *  - erf:/path/to/erf/file.gz
 *  - erf:/path/to/rtclient/socket
 *  - erf:-  (stdin)
 *  - dag:/dev/dagcard                  
 *  - pcapint:pcapinterface                (eg: pcap:eth0)
 *  - pcap:/path/to/pcap/file
 *  - pcap:-
 *  - rtclient:hostname
 *  - rtclient:hostname:port
 *  - wag:-
 *  - wag:/path/to/wag/file
 *  - wag:/path/to/wag/file.gz
 *  - wag:/path/to/wag/socket
 *
 *  If an error occured when attempting to open the trace file, NULL is returned
 *  and trace_errno is set. Use trace_perror() to get more information.  
 *  The trace is created in the configuration state, you must call trace_start
 *  to start the capture.
 */
struct libtrace_t *trace_create(const char *uri);

/** Creates a "dummy" trace file that has only the format type set.
 *
 * @return 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.
 */
struct libtrace_t *trace_create_dead(const char *uri);

/** Creates a trace output file from a URI. 
 *
 * @param uri   the uri string describing the output format and destination
 * @return opaque pointer to a libtrace_output_t
 * @author Shane Alcock
 *
 * Valid URI's are:
 *  - gzerf:/path/to/erf/file.gz
 *  - gzerf:/path/to/erf/file
 *  - rtserver:hostname
 *  - rtserver:hostname:port
 *
 *  If an error occured when attempting to open the output trace, NULL is returned 
 *  and trace_errno is set. Use trace_perror() to get more information
 */
libtrace_out_t *trace_create_output(const char *uri);

/** Start the capture
 * @param libtrace      The trace to start
 * @return 0 on success
 *
 * This does the actual work with starting the trace capture, and applying
 * all the config options.  This may fail.
 */
int trace_start(libtrace_t *libtrace);

/** Pause the capture
 * @param libtrace      The trace to pause
 * @return 0 on success
 *
 * This stops a capture in progress and returns you to the configuration
 * state.  Any packets that arrive after trace_pause() has been called
 * will be discarded.  To resume capture, call trace_start().
 */
int trace_pause(libtrace_t *libtrace);

/** Start an output trace
 * @param libtrace      The trace to start
 * @return 0 on success
 *
 * This does the actual work with starting a trace for write.  This generally
 * creates the file.
 */
int trace_start_output(libtrace_out_t *libtrace);

/** Valid trace capture options */
typedef enum {
        TRACE_OPTION_SNAPLEN, /**< Number of bytes captured */
        TRACE_OPTION_PROMISC, /**< Capture packets to other hosts */
        TRACE_OPTION_FILTER   /**< Apply this filter to all packets recieved */
} trace_option_t;

/** Sets an input config option
 * @param libtrace      the trace object to apply the option to
 * @param option        the option to set
 * @param value         the value to set the option to
 * @return -1 if option configuration failed, 0 otherwise
 * This should be called after trace_create, and before trace_start
 */
int trace_config(libtrace_t *libtrace,
                trace_option_t option,
                void *value);

typedef enum {
        TRACE_OPTION_OUTPUT_FILEFLAGS, /**< File flags to open the trace file
                                        * with.  eg O_APPEND
                                        */
        TRACE_OPTION_OUTPUT_COMPRESS   /**< Compression level, eg 6. */
} trace_option_output_t;

/** Sets an output config option
 *
 * @param libtrace      the output trace object to apply the option to
 * @param option        the option to set
 * @param value         the value to set the option to
 * @return -1 if option configuration failed, 0 otherwise
 * This should be called after trace_create_output, and before 
 * trace_start_output
 */
int trace_config_output(libtrace_out_t *libtrace, 
                trace_option_output_t option,
                void *value
                );

/** Close a trace file, freeing up any resources it may have been using
 *
 */
void trace_destroy(libtrace_t *trace);

/** Close a trace file, freeing up any resources it may have been using
 * @param trace         trace file to be destroyed
 */
void trace_destroy_dead(libtrace_t *trace);

/** Close a trace output file, freeing up any resources it may have been using
 *
 * @param trace         the output trace file to be destroyed
 *
 * @author Shane Alcock
 */
void trace_destroy_output(libtrace_out_t *trace);

/*@}*/

/** @name Reading/Writing packets
 * These members deal with creating, reading and writing packets
 *
 * @{
 */

/** Create a new packet object
 *
 * @return a pointer to an initialised libtrace_packet_t object
 */
libtrace_packet_t *trace_create_packet();

/** Copy a packet
 * @param packet        the source packet to copy
 * @return a new packet which has the same content as the source packet
 * @note This always involves a copy, which can be slow.  Use of this 
 * function should be avoided where possible.
 * @par The reason you would want to use this function is that a zerocopied
 * packet from a device is using the devices memory which may be a limited
 * resource.  Copying the packet will cause it to be copied into the systems
 * memory.
 */
libtrace_packet_t *trace_copy_packet(const libtrace_packet_t *packet);

/** Destroy a packet object
 *
 * sideeffect: sets packet to NULL
 */
void trace_destroy_packet(libtrace_packet_t **packet);


/** Read one packet from the trace into buffer
 *
 * @param trace         the libtrace opaque pointer
 * @param packet        the packet opaque pointer
 * @return 0 on EOF, negative value on error
 *
 * @note the trace must have been started with trace_start before calling
 * this function
 */
int trace_read_packet(libtrace_t *trace, libtrace_packet_t *packet);

/** Event types 
 * see \ref libtrace_eventobj_t and \ref trace_event
 */
typedef enum {
        TRACE_EVENT_IOWAIT,     /**< Need to block on fd */
        TRACE_EVENT_SLEEP,      /**< Sleep for some time */
        TRACE_EVENT_PACKET,     /**< packet has arrived */
        TRACE_EVENT_TERMINATE   /**< End of trace */
} libtrace_event_t;

/** structure returned by libtrace_event explaining what the current event is */
typedef struct libtrace_eventobj_t {
        libtrace_event_t type; /**< event type (iowait,sleep,packet) */
        int fd;                /**< if IOWAIT, the fd to sleep on */
        double seconds;        /**< if SLEEP, the amount of time to sleep for 
                                */
        int size;              /**< if PACKET, the value returned from 
                                *  trace_read_packet 
                                */
} libtrace_eventobj_t;

/** process a libtrace event
 * @param trace the libtrace opaque pointer
 * @param packet the libtrace_packet opaque pointer
 * @return libtrace_event struct containing the type, and potential
 *      fd or seconds to sleep on
 *
 * Type can be:
 *  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)
 */
libtrace_eventobj_t trace_event(libtrace_t *trace,
                libtrace_packet_t *packet);


/** Write one packet out to the output trace
 *
 * @param trace         the libtrace_out opaque pointer
 * @param packet        the packet opaque pointer
 * @return the number of bytes written out, if zero or negative then an error has occured.
 */
int trace_write_packet(libtrace_out_t *trace, const libtrace_packet_t *packet);
/*@}*/

/** @name Protocol decodes
 * These functions locate and return a pointer to various headers inside a
 * packet
 * @{
 */

/** get a pointer to the link layer
 * @param packet        the packet opaque pointer
 *
 * @return a pointer to the link layer, or NULL if there is no link layer
 *
 * @note you should call getLinkType() to find out what type of link layer 
 * this is
 */
SIMPLE_FUNCTION
void *trace_get_link(const libtrace_packet_t *packet);

/** get a pointer to the IP header (if any)
 * @param packet        the packet opaque pointer
 *
 * @return a pointer to the IP header, or NULL if there is not an IP packet
 */
SIMPLE_FUNCTION
libtrace_ip_t *trace_get_ip(const libtrace_packet_t *packet);

/** Gets a pointer to the transport layer header (if any)
 * @param packet        a pointer to a libtrace_packet structure
 *
 * @return a pointer to the transport layer header, or NULL if there is no header
 */
void *trace_get_transport(const libtrace_packet_t *packet);

/** Gets a pointer to the transport layer header (if any) given a pointer to the
 * IP header
 * @param ip            The IP Header
 * @param[out] skipped  An output variable of the number of bytes skipped
 *
 * @return a pointer to the transport layer header, or NULL if there is no header
 *
 * Skipped can be NULL, in which case it will be ignored
 */
void *trace_get_transport_from_ip(const libtrace_ip_t *ip, int *skipped);

/** get a pointer to the TCP header (if any)
 * @param packet        the packet opaque pointer
 *
 * @return a pointer to the TCP header, or NULL if there is not a TCP packet
 */
SIMPLE_FUNCTION
libtrace_tcp_t *trace_get_tcp(const libtrace_packet_t *packet);

/** get a pointer to the TCP header (if any) given a pointer to the IP header
 * @param ip            The IP header
 * @param[out] skipped  An output variable of the number of bytes skipped
 *
 * @return a pointer to the TCP header, or NULL if this is not a TCP packet
 *
 * Skipped can be NULL, in which case it will be ignored by the program.
 *
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
libtrace_tcp_t *trace_get_tcp_from_ip(const libtrace_ip_t *ip,int *skipped);

/** get a pointer to the UDP header (if any)
 * @param packet        the packet opaque pointer
 *
 * @return a pointer to the UDP header, or NULL if this is not a UDP packet
 */
SIMPLE_FUNCTION
libtrace_udp_t *trace_get_udp(const libtrace_packet_t *packet);

/** get a pointer to the UDP header (if any) given a pointer to the IP header
 * @param       ip      The IP header
 * @param[out]  skipped An output variable of the number of bytes skipped
 *
 * @return a pointer to the UDP header, or NULL if this is not an UDP packet
 *
 * Skipped may be NULL, in which case it will be ignored by this function.
 */
SIMPLE_FUNCTION
libtrace_udp_t *trace_get_udp_from_ip(const libtrace_ip_t *ip,int *skipped);

/** get a pointer to the ICMP header (if any)
 * @param packet        the packet opaque pointer
 *
 * @return a pointer to the ICMP header, or NULL if this is not a ICMP packet
 */
SIMPLE_FUNCTION
libtrace_icmp_t *trace_get_icmp(const libtrace_packet_t *packet);

/** get a pointer to the ICMP header (if any) given a pointer to the IP header
 * @param ip            The IP header
 * @param[out] skipped  An output variable of the number of bytes skipped
 *
 * @return a pointer to the ICMP header, or NULL if this is not an ICMP packet
 *
 * Skipped may be NULL, in which case it will be ignored by this function
 */
SIMPLE_FUNCTION
libtrace_icmp_t *trace_get_icmp_from_ip(const libtrace_ip_t *ip,int *skipped);
/*@}*/

/** parse an ip or tcp option
 * @param[in,out] ptr   the pointer to the current option
 * @param[in,out] len   the length of the remaining buffer
 * @param[out] type     the type of the option
 * @param[out] optlen   the length of the option
 * @param[out] data     the data of the option
 *
 * @return bool true if there is another option (and the fields are filled in)
 *               or false if this was the last option.
 *
 * This updates ptr to point to the next option after this one, and updates
 * len to be the number of bytes remaining in the options area.  Type is updated
 * to be the code of this option, and data points to the data of this option,
 * with optlen saying how many bytes there are.
 *
 * @note Beware of fragmented packets.
 */
int trace_get_next_option(unsigned char **ptr,int *len,
                        unsigned char *type,
                        unsigned char *optlen,
                        unsigned char **data);


/** @name Time
 * These functions deal with time that a packet arrived and return it
 * in various formats
 * @{
 */
/** Get the current time in DAG time format 
 * @param packet        the packet opaque pointer
 *
 * @return a 64 bit timestamp in DAG ERF format (upper 32 bits are the seconds
 * past 1970-01-01, the lower 32bits are partial seconds)
 * @author Daniel Lawson
 */
SIMPLE_FUNCTION
uint64_t trace_get_erf_timestamp(const libtrace_packet_t *packet);

/** Get the current time in struct timeval
 * @param packet        the packet opaque pointer
 *
 * @return time that this packet was seen in a struct timeval
 * @author Daniel Lawson
 * @author Perry Lorier
 */ 
SIMPLE_FUNCTION
struct timeval trace_get_timeval(const libtrace_packet_t *packet);

/** Get the current time in floating point seconds
 * @param packet        the packet opaque pointer
 *
 * @return time that this packet was seen in 64bit floating point seconds
 * @author Daniel Lawson
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
double trace_get_seconds(const libtrace_packet_t *packet);

/** Seek within a trace
 * @param trace         trace to seek
 * @param seconds       time to seek to
 * @return 0 on success.
 * Make the next packet read to be the first packet to occur at or after the
 * time searched for.  This must be called in the configuration state (ie,
 * before trace_start() or after trace_pause().
 * @note This function may be extremely slow.
 */
int trace_seek_seconds(libtrace_t *trace, double seconds);

/** Seek within a trace
 * @param trace         trace to seek
 * @param tv            time to seek to
 * @return 0 on success.
 * Make the next packet read to be the first packet to occur at or after the
 * time searched for.  This must be called in the configuration state (ie,
 * before trace_start() or after trace_pause().
 * @note This function may be extremely slow.
 */
int trace_seek_timeval(libtrace_t *trace, struct timeval tv);

/*@}*/

/** @name Sizes
 * This section deals with finding or setting the various different lengths
 * a packet can have
 * @{
 */
/** Get the size of the packet in the trace
 * @param packet        the packet opaque pointer
 * @return the size of the packet in the trace
 * @author Perry Lorier
 * @note Due to this being a header capture, or anonymisation, this may not
 * be the same size as the original packet.  See get_wire_length() for the
 * original size of the packet.
 * @note This can (and often is) different for different packets in a trace!
 * @note This is sometimes called the "snaplen".
 * @note The return size refers to the network-level payload of the packet and
 * does not include any capture headers. For example, an Ethernet packet with
 * an empty TCP packet will return sizeof(ethernet_header) + sizeof(ip_header)
 * + sizeof(tcp_header).
 */
SIMPLE_FUNCTION
int trace_get_capture_length(const libtrace_packet_t *packet);

/** Get the size of the packet as it was seen on the wire.
 * @param packet        the packet opaque pointer
 * @return 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.
 */ 
SIMPLE_FUNCTION
int trace_get_wire_length(const libtrace_packet_t *packet);

/** Get the length of the capture framing headers.
 * @param packet        the packet opaque pointer
 * @return the size of the packet as it was on the wire.
 * @author Perry Lorier
 * @author Daniel Lawson
 * @note this length corresponds to the difference between the size of a 
 * captured packet in memory, and the captured length of the packet
 */ 
SIMPLE_FUNCTION
int trace_get_framing_length(const libtrace_packet_t *packet);

/** Truncate ("snap") the packet at the suggested length
 * @param packet        the packet opaque pointer
 * @param size          the new length of the packet
 * @return the new capture length of the packet, or the original capture
 * length of the packet if unchanged
 */
size_t trace_set_capture_length(libtrace_packet_t *packet, size_t size);

/*@}*/


/** Link layer types
 * This enumates the various different link types that libtrace understands
 */
typedef enum { 
       TRACE_TYPE_LEGACY,       
       TRACE_TYPE_HDLC_POS, 
       TRACE_TYPE_ETH,                  /**< 802.3 style Ethernet */
       TRACE_TYPE_ATM,
       TRACE_TYPE_80211,                /**< 802.11 frames */
       TRACE_TYPE_NONE,
       TRACE_TYPE_LINUX_SLL,            /**< Linux "null" framing */
       TRACE_TYPE_PFLOG,                /**< FreeBSD's PFlug */
       TRACE_TYPE_LEGACY_DEFAULT,
       TRACE_TYPE_LEGACY_POS,
       TRACE_TYPE_LEGACY_ATM,
       TRACE_TYPE_LEGACY_ETH,
       TRACE_TYPE_80211_PRISM
     } libtrace_linktype_t;

/** Get the type of the link layer
 * @param packet        the packet opaque pointer
 * @return libtrace_linktype_t
 * @author Perry Lorier
 * @author Daniel Lawson
 */
SIMPLE_FUNCTION
inline libtrace_linktype_t trace_get_link_type(const libtrace_packet_t *packet);

/** Get the destination MAC addres
 * @param packet        the packet opaque pointer
 * @return a pointer to the destination mac, (or NULL if there is no 
 * destination MAC)
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
uint8_t *trace_get_destination_mac(const libtrace_packet_t *packet);

/** Get the source MAC addres
 * @param packet        the packet opaque pointer
 * @return a pointer to the source mac, (or NULL if there is no source MAC)
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
uint8_t *trace_get_source_mac(const libtrace_packet_t *packet);

/** Set the direction flag, if it has one
 * @param packet        the packet opaque pointer
 * @param direction     the new direction (0,1,2,3)
 * @return a signed value containing the direction flag, or -1 if this is not supported
 * @author Daniel Lawson
 */
int8_t trace_set_direction(libtrace_packet_t *packet, int8_t direction);

/** Get the direction flag, if it has one
 * @param packet        the packet opaque pointer
 * @return 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.
 * @author Daniel Lawson
 */
SIMPLE_FUNCTION
int8_t trace_get_direction(const libtrace_packet_t *packet);

/** @name BPF
 * This section deals with using Berkley Packet Filters
 * @{
 */
/** setup a BPF filter
 * @param filterstring a char * containing the bpf filter string
 * @return opaque pointer pointer to a libtrace_filter_t object
 * @author Daniel Lawson
 * @note The filter is not actually compiled at this point, so no correctness
 * tests are performed here. trace_bpf_setfilter will always return ok, but
 * if the filter is poorly constructed an error will be generated when the 
 * filter is actually used
 */
SIMPLE_FUNCTION
libtrace_filter_t *trace_bpf_setfilter(const char *filterstring);

/** apply a BPF filter
 * @param filter        the filter opaque pointer
 * @param packet        the packet opaque pointer
 * @return 1 if the filter matches, 0 if it doesn't.
 * @note Due to the way BPF filters are built, the filter is not actually
 * compiled until the first time trace_bpf_filter is called. If your filter is
 * incorrect, it will generate an error message and assert, exiting the
 * program. This behaviour may change to more graceful handling of this error
 * in the future.
 */
int trace_bpf_filter(libtrace_filter_t *filter,
                const libtrace_packet_t *packet);
/*@}*/

/** Which port is the server port */
typedef enum {
        USE_DEST,       /**< Destination port is the server port */
        USE_SOURCE      /**< Source port is the server port */
} serverport_t;

/** Get the source port
 * @param packet        the packet to read from
 * @return a port in \em HOST byte order, or equivilent to ports for this
 * protocol, or 0 if this protocol has no ports.
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
uint16_t trace_get_source_port(const libtrace_packet_t *packet);

/** Get the destination port
 * @param packet        the packet to read from
 * @return a port in \em HOST byte order, or equivilent to ports for this
 * protocol, or 0 if this protocol has no ports.
 * @author Perry Lorier
 */
SIMPLE_FUNCTION
uint16_t trace_get_destination_port(const libtrace_packet_t *packet);

/** hint at the server port in specified protocol
 * @param protocol      the IP layer protocol, eg 6 (tcp), 17 (udp)
 * @param source        the source port from the packet
 * @param dest          the destination port from the packet
 * @return one of USE_SOURCE or USE_DEST depending on which one you should use
 * @note ports must be in \em HOST byte order!
 * @author Daniel Lawson
 */
SIMPLE_FUNCTION
int8_t trace_get_server_port(uint8_t protocol, uint16_t source, uint16_t dest);

/** Takes a uri and splits it into a format and uridata component. 
 * Primarily for internal use but made available for external use.
 * @param uri           the uri to be parsed
 * @param format        destination location for the format component of the uri 
 * @return 0 if an error occured, otherwise return the uridata component
 * @author Shane Alcock
 */
const char *trace_parse_uri(const char *uri, char **format);

/* Base format type definitions */
enum base_format_t {
        TRACE_FORMAT_ERF          =1,
        TRACE_FORMAT_PCAP         =2,
        TRACE_FORMAT_WAG          =3,
        TRACE_FORMAT_RT           =4,
        TRACE_FORMAT_LEGACY_ATM   =5,
        TRACE_FORMAT_LEGACY_POS   =6,
        TRACE_FORMAT_LEGACY_ETH   =7
};

/** Gets the framing header type for a given packet.
 * @param packet        the packet opaque pointer
 * @return the format of the packet
 */
enum base_format_t trace_get_format(struct libtrace_packet_t *packet);


/** libtrace error information */
extern struct trace_err_t{
        int err_num;            /**< error code */
        char problem[255];      /**< the format, uri etc that caused the error for reporting purposes */
} trace_err;
#ifdef __cplusplus
} /* extern "C" */
#endif /* #ifdef __cplusplus */
#endif /* LIBTRACE_H_ */