source: lib/libtrace.h.in @ 77f79c7

/*
 * 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
 *
 * $Id$
 *
 */

#ifndef LIBTRACE_H
#define LIBTRACE_H

/** @file
 *
 * @brief Trace file processing library header
 *
 * @author Daniel Lawson
 * @author Perry Lorier
 * @author Shane Alcock
 *
 * @version $Id$
 *
 * This library provides a per packet interface into a trace file, or a live 
 * captures.  It supports ERF, DAG cards, PCAP, Linux and BSD native sockets,
 * legacy ERF formats 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>
#ifndef WIN32
#include <sys/time.h>
#endif

#ifdef _MSC_VER
    /* define the following from MSVC's internal types */
    typedef             __int8  int8_t;
    typedef             __int16 int16_t;
    typedef             __int32 int32_t;
    typedef             __int64 int64_t;
    typedef unsigned    __int8  uint8_t;
    typedef unsigned    __int16 uint16_t;
    typedef unsigned    __int32 uint32_t;
    typedef unsigned    __int64 uint64_t;
    #ifdef LT_BUILDING_DLL
        #define DLLEXPORT __declspec(dllexport)
    #else
        #define DLLEXPORT __declspec(dllimport)
    #endif
    #define DLLLOCAL
    /* Windows pads bitfields out to to the size of their parent type
     * however gcc warns that this doesn't meet with the iso C specification
     * so produces warnings for this behaviour.  sigh.
     */
    #define LT_BITFIELD8        uint8_t
    #define LT_BITFIELD16       uint16_t
    #define LT_BITFIELD32       uint32_t
    #define LT_BITFIELD64       uint64_t
#else
    #ifdef HAVE_STDINT_H
        #   include <stdint.h>
    #endif
    #if __GNUC__ >= 4
        #ifdef LT_BUILDING_DLL
                #define DLLEXPORT __attribute__ ((visibility("default")))
                #define DLLLOCAL __attribute__ ((visibility("hidden")))
        #else
                #define DLLEXPORT
                #define DLLLOCAL
        #endif
    #else
        #define DLLEXPORT
        #define DLLLOCAL
    #endif
    /* GCC warns if the bitfield type is not "unsigned int", however windows
     * generates incorrect code for this (see above), so we define these
     * macros.  How Hideous.  So much for C's portability.
     */
    #define LT_BITFIELD8        unsigned int
    #define LT_BITFIELD16       unsigned int
    #define LT_BITFIELD32       unsigned int
    #define LT_BITFIELD64       unsigned int
#endif

#ifdef WIN32
#   include <winsock2.h>
#   include <ws2tcpip.h>
    typedef short sa_family_t;
    /* Make up for a lack of stdbool.h */
#    define bool signed char
#    define false 0
#    define true 1
#    if !defined(ssize_t)
     /* XXX: Not 64-bit safe! */
#    define ssize_t int
#    endif    
#else
#    include <netinet/in.h>

#ifndef __cplusplus
#    include <stdbool.h>
#endif

#    include <sys/types.h>
#    include <sys/socket.h>
#endif

/** API version as 2 byte hex digits, eg 0xXXYYZZ */
#define LIBTRACE_API_VERSION \
            ((@LIBTRACE_MAJOR@<<16)|(@LIBTRACE_MID@<<8)|(@LIBTRACE_MINOR@))

/** Replaced with the current SVN revision number when 'make dist' is invoked
 *  to create a distributable tarball */
#define LIBTRACE_SVN_REVISION 0

/** DAG driver version installed on the current system */
#define DAG_DRIVER_V "@DAG_VERSION_NUM@"
    
#ifdef __cplusplus 
extern "C" { 
#endif

/* Function does not depend on anything but its
 * parameters, used to hint gcc's optimisations
 */
#if __GNUC__ >= 3 
#  define DEPRECATED __attribute__((deprecated))
#  define SIMPLE_FUNCTION __attribute__((pure))
#  define UNUSED __attribute__((unused))
#  define PACKED __attribute__((packed))
#  define PRINTF(formatpos,argpos) __attribute__((format(printf,formatpos,argpos)))
#else
#  define DEPRECATED
#  define SIMPLE_FUNCTION
#  define UNUSED
#  define PACKED 
#  define PRINTF(formatpos,argpos) 
#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;

/** If the packet has allocated its own memory the buffer_control should be
 * set to TRACE_CTRL_PACKET, so that the memory will be freed when the packet
 * is destroyed. If the packet has been zerocopied out of memory owned by
 * something else, e.g. a DAG card, it should be TRACE_CTRL_EXTERNAL.
 *
 * @note The letters p and e are magic numbers used to detect if the packet
 * wasn't created properly.
 */
typedef enum {
        TRACE_CTRL_PACKET='p',  /**< Buffer memory is owned by the packet */
        TRACE_CTRL_EXTERNAL='e' /**< Buffer memory is owned by an external source */
} buf_control_t;

/** The size of a packet's buffer when managed by libtrace */
#define LIBTRACE_PACKET_BUFSIZE 65536

/** Libtrace error information */
typedef struct trace_err_t{
        int err_num;            /**< error code */
        char problem[255];      /**< the format, uri etc that caused the error for reporting purposes */
} libtrace_err_t;

/** Enumeration of error codes */
enum {
        /** No Error has occured.... yet. */
        TRACE_ERR_NOERROR       = 0,
        /** The URI passed to trace_create() is unsupported, or badly formed */
        TRACE_ERR_BAD_FORMAT    = -1,
        /** The trace failed to initialise */
        TRACE_ERR_INIT_FAILED   = -2,
        /** Unknown config option */
        TRACE_ERR_UNKNOWN_OPTION= -3,
        /** This output uri cannot write packets of this type */
        TRACE_ERR_NO_CONVERSION = -4,
        /** This packet is corrupt, or unusable for the action required */ 
        TRACE_ERR_BAD_PACKET    = -5,
        /** Option known, but unsupported by this format */
        TRACE_ERR_OPTION_UNAVAIL= -6,
        /** This feature is unsupported */
        TRACE_ERR_UNSUPPORTED   = -7,
        /** Illegal use of the API */
        TRACE_ERR_BAD_STATE     = -8,
        /** Failed to compile a BPF filter */
        TRACE_ERR_BAD_FILTER    = -9,
        /** RT communication breakdown */
        TRACE_ERR_RT_FAILURE    = -10,
        /** Compression format unsupported */
        TRACE_ERR_UNSUPPORTED_COMPRESS  = -11
};

/** Enumeration of DLTs supported by libtrace 
 */
typedef enum {
        /** pcap documents this as having the Address Family value in host byte order as the 
          * framing.  Ugly? Yes.
          */
        TRACE_DLT_NULL = 0, 
        TRACE_DLT_EN10MB = 1,
        TRACE_DLT_PPP = 9,
        TRACE_DLT_ATM_RFC1483 = 11,
        
        /** Ok, so OpenBSD has a different value for DLT_RAW as the rest of the planet, so detect
          * this.  When reading to/from files we should be using TRACE_DLT_LINKTYPE_RAW instead.
          * When talking about DLT's inside libtrace tho, we should be using /these/ DLT's.
          */
#ifdef __OpenBSD__
        TRACE_DLT_RAW = 14,     
#else
        TRACE_DLT_RAW = 12,
#endif
        TRACE_DLT_PPP_SERIAL = 50,
        TRACE_DLT_LINKTYPE_RAW = 101, /**< See TRACE_DLT_RAW for explainations of pain. */
        TRACE_DLT_C_HDLC = 104,
        TRACE_DLT_IEEE802_11 = 105,
        TRACE_DLT_OPENBSD_LOOP = 108,
        TRACE_DLT_LINUX_SLL = 113,
        TRACE_DLT_PFLOG = 117,
        TRACE_DLT_IEEE802_11_RADIO = 127 /**< Radiotap */
} libtrace_dlt_t ;

/** Enumeration of link layer types supported by libtrace */
typedef enum { 
    /* TRACE_TYPE_LEGACY = 0            Obsolete */
       TRACE_TYPE_HDLC_POS = 1,         /**< HDLC over POS */
       TRACE_TYPE_ETH = 2,              /**< 802.3 style Ethernet */
       TRACE_TYPE_ATM = 3,              /**< ATM frame */
       TRACE_TYPE_80211 = 4,            /**< 802.11 frames */
       TRACE_TYPE_NONE = 5,             /**< Raw IP frames */
       TRACE_TYPE_LINUX_SLL = 6,        /**< Linux "null" framing */
       TRACE_TYPE_PFLOG = 7,            /**< FreeBSD's PFlog */
    /* TRACE_TYPE_LEGACY_DEFAULT        Obsolete */
       TRACE_TYPE_POS = 9,              /**< Packet-over-SONET */
    /* TRACE_TYPE_LEGACY_ATM            Obsolete */
    /* TRACE_TYPE_LEGACY_ETH            Obsolete */
       TRACE_TYPE_80211_PRISM = 12,     /**< 802.11 Prism frames */
       TRACE_TYPE_AAL5 = 13,            /**< ATM Adaptation Layer 5 frames */
       TRACE_TYPE_DUCK = 14,         /**< Pseudo link layer for DUCK packets */
       TRACE_TYPE_80211_RADIO = 15,  /**< Radiotap + 802.11 */
       TRACE_TYPE_LLCSNAP = 16,      /**< Raw LLC/SNAP */
       TRACE_TYPE_PPP = 17,          /**< PPP frames */
       TRACE_TYPE_METADATA = 18,        /**< WDCAP-style meta-data */
       TRACE_TYPE_NONDATA = 19,         /**< Not a data packet */
       TRACE_TYPE_OPENBSD_LOOP = 20     /**< OpenBSD loopback */
} libtrace_linktype_t;

/** RT protocol base format identifiers.
 * This is used to describe the capture format of the packet is being sent 
 * using the RT protocol.
 */ 
enum base_format_t {
        TRACE_FORMAT_ERF          =1,   /**< ERF (DAG capture format) */
        TRACE_FORMAT_PCAP         =2,   /**< Live PCAP capture */
        TRACE_FORMAT_PCAPFILE     =3,   /**< PCAP trace file */ 
        TRACE_FORMAT_WAG          =4,   /**< WAG live capture (Obsolete) */
        TRACE_FORMAT_RT           =5,   /**< RT network protocol */
        TRACE_FORMAT_LEGACY_ATM   =6,   /**< Legacy ERF for ATM capture */
        TRACE_FORMAT_LEGACY_POS   =7,   /**< Legacy ERF for POS capture */
        TRACE_FORMAT_LEGACY_ETH   =8,   /**< Legacy ERF for ETH capture */
        TRACE_FORMAT_LINUX_NATIVE =9,   /**< Linux native interface capture */
        TRACE_FORMAT_DUCK         =10,  /**< DAG Clock information */
        TRACE_FORMAT_BPF          =11,  /**< BSD native interface capture */
        TRACE_FORMAT_TSH          =12,  /**< TSH trace format */
        TRACE_FORMAT_ATMHDR       =13,  /**< Legacy ATM header capture */
        TRACE_FORMAT_LEGACY_NZIX  =14,  /**< Legacy format used for NZIX traces */
        TRACE_FORMAT_LINUX_RING   =15   /**< Linux native interface capture PACKET_MMAP */
};

/** RT protocol packet types */
typedef enum {
        TRACE_RT_HELLO          =1, /**< Connection accepted */
        TRACE_RT_START          =2, /**< Request for data transmission to begin 
                                    */
        TRACE_RT_ACK            =3, /**< Data acknowledgement */
        TRACE_RT_STATUS         =4, /**< Fifo status packet */
        TRACE_RT_DUCK           =5, /**< Dag duck info packet */
        TRACE_RT_END_DATA       =6, /**< Server is exiting message */
        TRACE_RT_CLOSE          =7, /**< Client is exiting message */
        TRACE_RT_DENY_CONN      =8, /**< Connection has been denied */
        TRACE_RT_PAUSE          =9, /**< Request server to suspend sending data 
                                     */
        TRACE_RT_PAUSE_ACK      =10,/**< Server is paused message */
        TRACE_RT_OPTION         =11,/**< Option request */
        TRACE_RT_KEYCHANGE      =12,/**< Anonymisation key has changed */ 
        TRACE_RT_DUCK_2_4       =13,/**< Dag 2.4 Duck */
        TRACE_RT_DUCK_2_5       =14,/**< Dag 2.5 Duck */
        TRACE_RT_LOSTCONN       =15,/**< Lost connection to server */
        TRACE_RT_SERVERSTART    =16,/**< Reliable server has been restarted */
        TRACE_RT_CLIENTDROP     =17,/**< Reliable client was lost */
        TRACE_RT_METADATA       =18,/**< Packet contains server meta-data */

        /** Not actually used - all DATA types begin from this value */
        TRACE_RT_DATA_SIMPLE    = 1000, 
        
        /** RT is encapsulating an ERF capture record */
        TRACE_RT_DATA_ERF       =TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_ERF, 
        /** RT is encapsulating a WAG capture record */
        TRACE_RT_DATA_WAG       =TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_WAG, 
        /** RT is encapsulating a Legacy ATM capture record */
        TRACE_RT_DATA_LEGACY_ATM=TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_LEGACY_ATM, 
        /** RT is encapsulating a Legacy POS capture record */
        TRACE_RT_DATA_LEGACY_POS=TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_LEGACY_POS, 
        /** RT is encapsulating a Legacy ETH capture record */
        TRACE_RT_DATA_LEGACY_ETH=TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_LEGACY_ETH, 
        /** RT is encapsulating a Linux native capture record */
        TRACE_RT_DATA_LINUX_NATIVE=TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_LINUX_NATIVE,
        /** RT is encapsulating a BSD native capture record */
        //TRACE_RT_DATA_BPF       =TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_BPF,
        /** RT is encapsulating a TSH capture record */
        TRACE_RT_DATA_TSH       =TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_TSH,
        /** RT is encapsulating an ATM header capture record */
        TRACE_RT_DATA_ATMHDR = TRACE_RT_DATA_SIMPLE + TRACE_FORMAT_ATMHDR,
        /** RT is encapsulating a Legacy NZIX capture record */
        TRACE_RT_DATA_LEGACY_NZIX=TRACE_RT_DATA_SIMPLE + TRACE_FORMAT_LEGACY_NZIX,
        /** RT is encapsulating a Linux native PACKET_MMAP capture record */
        TRACE_RT_DATA_LINUX_RING=TRACE_RT_DATA_SIMPLE+TRACE_FORMAT_LINUX_RING,

        /** As PCAP does not store the linktype with the packet, we need to 
         * create a separate RT type for each supported DLT, starting from
         * this value */
        TRACE_RT_DATA_DLT               = 2000, 
        /** RT is encapsulating a PCAP capture record with a NULL linktype */ 
        TRACE_RT_DLT_NULL               =TRACE_RT_DATA_DLT+TRACE_DLT_NULL,
        /** RT is encapsulating a PCAP capture record with an Ethernet 
         * linktype */ 
        TRACE_RT_DLT_EN10MB             =TRACE_RT_DATA_DLT+TRACE_DLT_EN10MB,
        /** RT is encapsulating a PCAP capture record with an 802.11 
         * linktype */ 
        TRACE_RT_DLT_IEEE802_11         =TRACE_RT_DATA_DLT+TRACE_DLT_IEEE802_11,
        /** RT is encapsulating a PCAP capture record with a Linux SLL 
         * linktype */ 
        TRACE_RT_DLT_LINUX_SLL          =TRACE_RT_DATA_DLT+TRACE_DLT_LINUX_SLL,
        /** RT is encapsulating a PCAP capture record with a PFlog linktype */ 
        TRACE_RT_DLT_PFLOG              =TRACE_RT_DATA_DLT+TRACE_DLT_PFLOG,
        /** RT is encapsulating a PCAP capture record with an AAL5 linktype */ 
        TRACE_RT_DLT_ATM_RFC1483        =TRACE_RT_DATA_DLT+TRACE_DLT_ATM_RFC1483,
        /** Unused value marking the end of the valid range for PCAP RT 
         * encapsulation */
        TRACE_RT_DATA_DLT_END           = 2999,
        /** BPF does not store the linktype with the packet, so we need a
         * separate RT type for each supported DLT. This value represents the
         * starting point */
        TRACE_RT_DATA_BPF               = 3000,

        TRACE_RT_BPF_NULL               = TRACE_RT_DATA_BPF+TRACE_DLT_NULL,
        TRACE_RT_BPF_EN10MB             = TRACE_RT_DATA_BPF+TRACE_DLT_EN10MB,
        TRACE_RT_BPF_IEEE802_11         = TRACE_RT_DATA_BPF+TRACE_DLT_IEEE802_11,
        TRACE_RT_BPF_PFLOG              =TRACE_RT_DATA_BPF+TRACE_DLT_PFLOG,
        TRACE_RT_BPF_ATM_RFC1483        =TRACE_RT_DATA_BPF+TRACE_DLT_ATM_RFC1483,

        TRACE_RT_DATA_BPF_END           = 3999,
        /** Unused value marking the end of the valid range for all RT packet
         * types */
        TRACE_RT_LAST                   = 4000
} libtrace_rt_types_t;

/** IP Protocol values */
typedef enum {
        TRACE_IPPROTO_IP        = 0,    /**< IP pseudo protocol number */
        TRACE_IPPROTO_ICMP      = 1,    /**< Internet Control Message protocol */
        TRACE_IPPROTO_IGMP      = 2,    /**< Internet Group Management Protocol */
        TRACE_IPPROTO_IPIP      = 4,    /**< IP encapsulated in IP */
        TRACE_IPPROTO_TCP       = 6,    /**< Transmission Control Protocol */
        TRACE_IPPROTO_UDP       = 17,   /**< User Datagram Protocol */
        TRACE_IPPROTO_IPV6      = 41,   /**< IPv6 over IPv4 */
        TRACE_IPPROTO_ROUTING   = 43,   /**< IPv6 Routing header */
        TRACE_IPPROTO_FRAGMENT  = 44,   /**< IPv6 Fragmentation header */
        TRACE_IPPROTO_RSVP      = 46,   /**< Resource Reservation Protocol */
        TRACE_IPPROTO_GRE       = 47,   /**< General Routing Encapsulation */
        TRACE_IPPROTO_ESP       = 50,   /**< Encapsulated Security Payload [RFC2406] */
        TRACE_IPPROTO_AH        = 51,   /**< Authentication Header [RFC2402] */
        TRACE_IPPROTO_ICMPV6    = 58,   /**< ICMPv6 */
        TRACE_IPPROTO_NONE      = 59,   /**< IPv6 no next header */
        TRACE_IPPROTO_DSTOPTS   = 60,   /**< IPv6 destination options */
        TRACE_IPPROTO_OSPF      = 89,   /**< Open Shortest Path First routing protocol */
        TRACE_IPPROTO_PIM       = 103,  /**< Protocol Independant Multicast */
        TRACE_IPPROTO_SCTP      = 132   /**< Stream Control Transmission Protocol */
} libtrace_ipproto_t;

/** Ethertypes supported by Libtrace */
typedef enum {
        /* Numbers <=1500 are of course, LLC/SNAP */
        TRACE_ETHERTYPE_LOOPBACK= 0x0060,       /**< Ethernet Loopback */
        TRACE_ETHERTYPE_IP      = 0x0800,       /**< IPv4 */
        TRACE_ETHERTYPE_ARP     = 0x0806,       /**< Address resolution protocol */
        TRACE_ETHERTYPE_RARP    = 0x8035,       /**< Reverse ARP */
        TRACE_ETHERTYPE_8021Q   = 0x8100,       /**< 802.1q VLAN Extended Header */
        TRACE_ETHERTYPE_IPV6    = 0x86DD,       /**< IPv6 */
        TRACE_ETHERTYPE_MPLS    = 0x8847,       /**< MPLS Unicast traffic */
        TRACE_ETHERTYPE_MPLS_MC = 0x8848,       /**< MPLS Multicast traffic */
        TRACE_ETHERTYPE_PPP_DISC= 0x8863,       /**< PPPoE Service Discovery */
        TRACE_ETHERTYPE_PPP_SES = 0x8864        /**< PPPoE Session Messages */
} libtrace_ethertype_t;

/** The libtrace packet structure. Applications shouldn't be 
 * meddling around in here 
 */
typedef struct libtrace_packet_t {
        struct libtrace_t *trace;       /**< Pointer to the trace */
        void *header;                   /**< Pointer to the framing header */
        void *payload;                  /**< Pointer to the link layer */
        void *buffer;                   /**< Allocated buffer */
        libtrace_rt_types_t  type;      /**< RT protocol type for the packet */
        buf_control_t buf_control;      /**< Describes memory ownership */
        int capture_length;             /**< Cached capture length */
        int wire_length;                /**< Cached wire length */
        int payload_length;             /**< Cached payload length */
        void *l2_header;                /**< Cached link header */
        libtrace_linktype_t link_type;  /**< Cached link type */
        uint32_t l2_remaining;          /**< Cached link remaining */
        void *l3_header;                /**< Cached l3 header */
        uint16_t l3_ethertype;          /**< Cached l3 ethertype */
        uint32_t l3_remaining;          /**< Cached l3 remaining */
        void *l4_header;                /**< Cached transport header */
        uint8_t transport_proto;        /**< Cached transport protocol */
        uint32_t l4_remaining;          /**< Cached transport remaining */
} libtrace_packet_t;


/** Trace directions. 
 * Note that these are the directions used by convention. More directions 
 * are possible, not just these 3, and that they may not conform to this
 * convention.
 */
typedef enum {
        TRACE_DIR_OUTGOING = 0,         /**< Packets originating "inside" */
        TRACE_DIR_INCOMING = 1,         /**< Packets originating "outside" */
        TRACE_DIR_OTHER    = 2          /**< Packets with an unknown direction, or one that's unknown */
} libtrace_direction_t;

/** Enumeration of Radiotap fields */
typedef enum {
    TRACE_RADIOTAP_TSFT = 0, /**< Timer synchronisation function, in microseconds (uint64) */
    TRACE_RADIOTAP_FLAGS = 1, /**< Wireless flags (uint8) */
    TRACE_RADIOTAP_RATE = 2, /**< Bitrate in units of 500kbps (uint8) */
    TRACE_RADIOTAP_CHANNEL = 3, /**< Frequency in MHz (uint16) and channel flags (uint16) */
    TRACE_RADIOTAP_FHSS = 4, /**< FHSS hop set (uint8) and hopping pattern (uint8) */
    TRACE_RADIOTAP_DBM_ANTSIGNAL = 5, /**< Signal power in dBm (int8) */
    TRACE_RADIOTAP_DBM_ANTNOISE = 6, /**< Noise power in dBm (int8) */
    TRACE_RADIOTAP_LOCK_QUALITY = 7, /**< Barker Code lock quality (uint16) */
    TRACE_RADIOTAP_TX_ATTENUATION = 8, /**< TX attenuation as unitless distance from max power (uint16) */
    TRACE_RADIOTAP_DB_TX_ATTENUATION = 9, /**< TX attenutation as dB from max power (uint16) */
    TRACE_RADIOTAP_DBM_TX_POWER = 10, /**< TX Power in dBm (int8) */
    TRACE_RADIOTAP_ANTENNA = 11, /**< Antenna frame was rx'd or tx'd on (uint8) */
    TRACE_RADIOTAP_DB_ANTSIGNAL = 12, /**< Signal power in dB from a fixed reference (uint8) */
    TRACE_RADIOTAP_DB_ANTNOISE = 13, /**< Noise power in dB from a fixed reference (uint8) */
    TRACE_RADIOTAP_RX_FLAGS = 14, /** Properties of received frame (uint16) */
    TRACE_RADIOTAP_TX_FLAGS = 15, /** Properties of transmitted frame (uint16) */
    TRACE_RADIOTAP_RTS_RETRIES = 16, /** Number of rts retries frame used (uint8) */
    TRACE_RADIOTAP_DATA_RETRIES = 17, /** Number of unicast retries a transmitted frame used (uint8) */
    TRACE_RADIOTAP_EXT = 31
} libtrace_radiotap_field_t;


/** @name Protocol structures
 * These convenience structures provide portable versions of the headers
 * for a variety of protocols.
 * @{
 */

#ifdef WIN32
#pragma pack(push)
#pragma pack(1)
#endif

/** Generic IP header structure */
typedef struct libtrace_ip
{
#if BYTE_ORDER == LITTLE_ENDIAN
    LT_BITFIELD8 ip_hl:4;               /**< Header Length */
    LT_BITFIELD8 ip_v:4;                /**< Version */
#elif BYTE_ORDER == BIG_ENDIAN
    LT_BITFIELD8 ip_v:4;                /**< Version */
    LT_BITFIELD8 ip_hl:4;               /**< Header Length */
#else
#   error "Adjust your <bits/endian.h> defines"
#endif
    uint8_t  ip_tos;                    /**< Type of Service */
    uint16_t ip_len;                    /**< Total Length */
    int16_t  ip_id;                     /**< Identification */
    uint16_t ip_off;                    /**< IP Fragment offset (and flags) */
    uint8_t  ip_ttl;                    /**< Time to Live */
    uint8_t  ip_p;                      /**< Protocol */
    uint16_t ip_sum;                    /**< Checksum */
    struct in_addr ip_src;              /**< Source Address */
    struct in_addr ip_dst;              /**< Destination Address */
} PACKED libtrace_ip_t;

/** IPv6 header extension structure */
typedef struct libtrace_ip6_ext
{
        uint8_t nxt;    /**< Next header */
        uint8_t len;    /**< Length of the current header */
} PACKED libtrace_ip6_ext_t;

typedef struct libtrace_ip6_frag 
{
        uint8_t nxt;    /**< Next header */
        uint8_t res;    /**< Reserved */
        uint16_t frag_off;      /**< Fragment Offset (includes M flag) */
        uint32_t ident; /** Fragment identification */
} PACKED libtrace_ip6_frag_t;

/** Generic IPv6 header structure
 *
 * @note The flow label field also includes the Version and Traffic Class
 * fields, because we haven't figured out a nice way to deal with fields
 * crossing byte boundaries on both Big and Little Endian machines */
typedef struct libtrace_ip6
{ 
    uint32_t flow;                      /**< Flow label */
    uint16_t plen;                      /**< Payload length */
    uint8_t nxt;                        /**< Next header */
    uint8_t hlim;                       /**< Hop limit */
    struct in6_addr ip_src;             /**< Source address */
    struct in6_addr ip_dst;             /**< Destination address */
} PACKED libtrace_ip6_t;

/** Generic TCP header structure */
typedef struct libtrace_tcp
  {
    uint16_t source;            /**< Source Port */
    uint16_t dest;              /**< Destination port */
    uint32_t seq;               /**< Sequence number */
    uint32_t ack_seq;           /**< Acknowledgement Number */
#  if BYTE_ORDER == LITTLE_ENDIAN
    LT_BITFIELD8 ecn_ns:1;      /**< ECN Nonce Sum */
    LT_BITFIELD8 res1:3;        /**< Reserved bits */
    LT_BITFIELD8 doff:4;        /**< Data Offset */
    LT_BITFIELD8 fin:1;         /**< FIN */
    LT_BITFIELD8 syn:1;         /**< SYN flag */
    LT_BITFIELD8 rst:1;         /**< RST flag */
    LT_BITFIELD8 psh:1;         /**< PuSH flag */
    LT_BITFIELD8 ack:1;         /**< ACK flag */
    LT_BITFIELD8 urg:1;         /**< URG flag */
    LT_BITFIELD8 ece:1;         /**< ECN Echo */
    LT_BITFIELD8 cwr:1;         /**< ECN CWR */
#  elif BYTE_ORDER == BIG_ENDIAN
    LT_BITFIELD8 doff:4;        /**< Data offset */
    LT_BITFIELD8 res1:3;        /**< Reserved bits */
    LT_BITFIELD8 ecn_ns:1;      /**< ECN Nonce Sum */
    LT_BITFIELD8 cwr:1;         /**< ECN CWR */
    LT_BITFIELD8 ece:1;         /**< ECN Echo */
    LT_BITFIELD8 urg:1;         /**< URG flag */
    LT_BITFIELD8 ack:1;         /**< ACK flag */
    LT_BITFIELD8 psh:1;         /**< PuSH flag */
    LT_BITFIELD8 rst:1;         /**< RST flag */
    LT_BITFIELD8 syn:1;         /**< SYN flag */
    LT_BITFIELD8 fin:1;         /**< FIN flag */
#  else
#   error "Adjust your <bits/endian.h> defines"
#  endif
    uint16_t window;            /**< Window Size */
    uint16_t check;             /**< Checksum */
    uint16_t urg_ptr;           /**< Urgent Pointer */
} PACKED libtrace_tcp_t;

/** Generic UDP header structure */
typedef struct libtrace_udp {
  uint16_t      source;         /**< Source port */
  uint16_t      dest;           /**< Destination port */
  uint16_t      len;            /**< Length */
  uint16_t      check;          /**< Checksum */
} PACKED libtrace_udp_t;

/** Generic ICMP header structure */
typedef struct libtrace_icmp
{
  uint8_t type;         /**< Message Type */
  uint8_t code;         /**< Type Sub-code */
  uint16_t checksum;            /**< Checksum */
  union
  {
    struct
    {
      uint16_t  id;             /**< ID of the Echo request */
      uint16_t  sequence;       /**< Sequence number of the Echo request */
    } echo;                     /**< Echo Datagram */
    uint32_t    gateway;        /**< Gateway Address */
    struct
    {
      uint16_t  unused;         /**< Unused */
      uint16_t  mtu;            /**< Next-hop MTU */
    } frag;                     /**< Path MTU Discovery */
  } un;                         /**< Union for Payloads of Various ICMP Codes */
} PACKED libtrace_icmp_t;

typedef struct libtrace_icmp6 {
  uint8_t type;         /**< Message Type */
  uint8_t code;         /**< Type Sub-code */
  uint16_t checksum;    /**< Checksum */

  union {
    struct {
        uint8_t length;   /**< Length of original datagram content in 64 bit words */
        uint8_t unused;   /**< Unused */        
        uint8_t unused1;  /**< Unused */
    } extend;   /**< Extensions added in RFC 4884 for Time Exceeded and Destination Unreachable Messages */

    uint32_t mtu;       /**< MTU from Packet Too Big Message */
    uint32_t pointer;   /**< Pointer from Parameter Problem Message */
    struct {
        uint16_t id;    /**< Echo Identifier */
        uint16_t sequence; /**< Echo Sequence Number */
    } echo; /**< Data required for Echo Request and Reply messages */
  } un;
} PACKED libtrace_icmp6_t;

/** Generic LLC/SNAP header structure */
typedef struct libtrace_llcsnap
{
/* LLC */
  uint8_t dsap;                 /**< Destination Service Access Point */
  uint8_t ssap;                 /**< Source Service Access Point */
  uint8_t control;              /**< Control field */
/* SNAP */
  LT_BITFIELD32 oui:24;         /**< Organisationally Unique Identifier (scope)*/
  uint16_t type;                /**< Protocol within OUI */
} PACKED libtrace_llcsnap_t;

/** 802.3 frame */
typedef struct libtrace_ether
{
  uint8_t ether_dhost[6];       /**< Destination Ether Addr */
  uint8_t ether_shost[6];       /**< Source Ether Addr */
  uint16_t ether_type;          /**< Packet Type ID Field (next-header) */
} PACKED libtrace_ether_t;

/** 802.1Q frame */
typedef struct libtrace_8021q 
{
  LT_BITFIELD16 vlan_pri:3;      /**< VLAN User Priority */
  LT_BITFIELD16 vlan_cfi:1;      /**< VLAN Format Indicator, 
                                   * 0 for ethernet, 1 for token ring */
  LT_BITFIELD16 vlan_id:12;      /**< VLAN Id */
  uint16_t vlan_ether_type;      /**< VLAN Sub-packet Type ID Field 
                                   * (next-header)*/
} PACKED libtrace_8021q_t;

/** ATM User Network Interface (UNI) Cell. */
typedef struct libtrace_atm_cell
{
  LT_BITFIELD32 gfc:4;          /**< Generic Flow Control */
  LT_BITFIELD32 vpi:8;          /**< Virtual Path Identifier */
  LT_BITFIELD32 vci:16;         /**< Virtual Channel Identifier */
  LT_BITFIELD32 pt:3;           /**< Payload Type */
  LT_BITFIELD32 clp:1;          /**< Cell Loss Priority */
  LT_BITFIELD32 hec:8;          /**< Header Error Control */
} PACKED libtrace_atm_cell_t;

/** ATM Network Node/Network Interface (NNI) Cell. */
typedef struct libtrace_atm_nni_cell
{
  LT_BITFIELD32 vpi:12;         /**< Virtual Path Identifier */
  LT_BITFIELD32 vci:16;         /**< Virtual Channel Identifier */
  LT_BITFIELD32 pt:3;           /**< Payload Type */
  LT_BITFIELD32 clp:1;          /**< Cell Loss Priority */
  LT_BITFIELD32 hec:8;          /**< Header Error Control */
} PACKED libtrace_atm_nni_cell_t;

/** Captured UNI cell.
 *
 * Endace don't capture the HEC, presumably to keep alignment.  This 
 * version of the \ref libtrace_atm_cell is used when dealing with DAG 
 * captures of uni cells.
 *
 */
typedef struct libtrace_atm_capture_cell
{
  LT_BITFIELD32 gfc:4;          /**< Generic Flow Control */
  LT_BITFIELD32 vpi:8;          /**< Virtual Path Identifier */
  LT_BITFIELD32 vci:16;         /**< Virtual Channel Identifier */
  LT_BITFIELD32 pt:3;           /**< Payload Type */
  LT_BITFIELD32 clp:1;          /**< Cell Loss Priority */
} PACKED libtrace_atm_capture_cell_t;

/** Captured NNI cell.
 *
 * Endace don't capture the HEC, presumably to keep alignment.  This 
 * version of the \ref libtrace_atm_nni_cell is used when dealing with DAG
 * captures of nni cells.
 *
 */
typedef struct libtrace_atm_nni_capture_cell
{
  LT_BITFIELD32 vpi:12;         /**< Virtual Path Identifier */
  LT_BITFIELD32 vci:16;         /**< Virtual Channel Identifier */
  LT_BITFIELD32 pt:3;           /**< Payload Type */
  LT_BITFIELD32 clp:1;          /**< Cell Loss Priority */
  LT_BITFIELD32 hec:8;          /**< Header Error Control */
} PACKED libtrace_atm_nni_capture_cell_t;

/** PPP header */
typedef struct libtrace_ppp
{
 /* I can't figure out where the hell these two variables come from. They're
  * definitely not in RFC 1661 which defines PPP. Probably some weird thing
  * relating to the lack of distinction between PPP, HDLC and CHDLC */
        
/* uint8_t address; */          /**< PPP Address (0xFF - All stations) */
/* uint8_t header;  */          /**< PPP Control (0x03 - Unnumbered info) */
 uint16_t protocol;             /**< PPP Protocol (htons(0x0021) - IPv4 */
} PACKED libtrace_ppp_t;

/** PPPoE header */
typedef struct libtrace_pppoe
{
 LT_BITFIELD8 version:4;        /**< Protocol version number */
 LT_BITFIELD8 type:4;           /**< PPPoE Type */
 uint8_t code;                  /**< PPPoE Code */
 uint16_t session_id;           /**< Session Identifier */
 uint16_t length;               /**< Total Length of the PPP packet */
} PACKED libtrace_pppoe_t;

/** 802.11 header */
typedef struct libtrace_80211_t {
#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD32      protocol:2;  /**< Protocol Version */
        LT_BITFIELD32      type:2;      /**< Frame Type */
        LT_BITFIELD32      subtype:4;   /**< Frame Subtype */
#else
        LT_BITFIELD32      subtype:4;   /**< Frame Subtype */
        LT_BITFIELD32      type:2;      /**< Frame Type */
        LT_BITFIELD32      protocol:2;  /**< Protocol Version */
#endif

#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD32      to_ds:1;     /**< Packet to Distribution Service */
        LT_BITFIELD32      from_ds:1;   /**< Packet from Distribution Service */
        LT_BITFIELD32      more_frag:1; /**< Packet has more fragments */
        LT_BITFIELD32      retry:1;     /**< Packet is a retry */
        LT_BITFIELD32      power:1;     /**< Power Management mode */
        LT_BITFIELD32      more_data:1; /**< More data is buffered at station */
        LT_BITFIELD32      wep:1;       /**< WEP encryption indicator */
        LT_BITFIELD32      order:1;     /**< Strictly-Ordered class indicator */
#else
        LT_BITFIELD32      order:1;     /**< Strictly-Ordered class indicator */
        LT_BITFIELD32      wep:1;       /**< WEP encryption indicator */
        LT_BITFIELD32      more_data:1; /**< More data is buffered at station */
        LT_BITFIELD32      power:1;     /**< Power Management mode */
        LT_BITFIELD32      retry:1;     /**< Packet is a retry */
        LT_BITFIELD32      more_frag:1; /**< Packet has more fragments */
        LT_BITFIELD32      from_ds:1;   /**< Packet from Distribution Service */
        LT_BITFIELD32      to_ds:1;     /**< Packet to Distribution Service */
#endif
        
        uint16_t     duration;  /**< Duration value for NAV calculation */
        uint8_t      mac1[6];   /**< MAC Address 1 */
        uint8_t      mac2[6];   /**< MAC Address 2 */
        uint8_t      mac3[6];   /**< MAC Address 3 */
        uint16_t     SeqCtl;    /**< Sequence Control */        
        uint8_t      mac4[6];   /**< MAC Address 4 */
} PACKED libtrace_80211_t;

/** The Radiotap header pre-amble
 *
 * All Radiotap headers start with this pre-amble, followed by the fields
 * specified in the it_present bitmask. If bit 31 of it_present is set, then
 * another bitmask follows.
 * @note All of the radiotap data fields are in little-endian byte-order.
 */
typedef struct libtrace_radiotap_t {
    uint8_t     it_version; /**< Radiotap version */
    uint8_t     it_pad; /**< Padding for natural alignment */
    uint16_t    it_len; /**< Length in bytes of the entire Radiotap header */
    uint32_t    it_present; /**< Which Radiotap fields are present */
} PACKED libtrace_radiotap_t;

/** OSPF header */
typedef struct libtrace_ospf_v2_t
{
        uint8_t ospf_v;         /**< OSPF Version, should be 2 */
        uint8_t type;           /**< OSPF Packet Type */
        uint16_t len;           /**< Packet length, including OSPF header */
        struct in_addr router;  /**< Router ID of the packet source */
        struct in_addr area;    /**< Area the packet belongs to */
        uint16_t sum;           /**< Checksum */
        uint16_t au_type;       /**< Authentication procedure */
        uint16_t zero;          /**< Always zero */
        uint8_t au_key_id;      /**< Authentication Key ID */
        uint8_t au_data_len;    /**< Authentication Data Length */
        uint32_t au_seq_num;    /**< Cryptographic Sequence Number */
} PACKED libtrace_ospf_v2_t;

/** Options Field present in some OSPFv2 packets */
typedef struct libtrace_ospf_options_t {
#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD8 unused1:1;
        LT_BITFIELD8 e_bit:1;
        LT_BITFIELD8 mc_bit:1;
        LT_BITFIELD8 np_bit:1;
        LT_BITFIELD8 ea_bit:1;
        LT_BITFIELD8 dc_bit:1;
        LT_BITFIELD8 unused2:2;
#elif BYTE_ORDER == BIG_ENDIAN
        LT_BITFIELD8 unused2:2;
        LT_BITFIELD8 dc_bit:1;
        LT_BITFIELD8 ea_bit:1;
        LT_BITFIELD8 np_bit:1;
        LT_BITFIELD8 mc_bit:1;
        LT_BITFIELD8 e_bit:1;
        LT_BITFIELD8 unused1:1;
#endif
} PACKED libtrace_ospf_options_t;

/** LSA Header for OSPFv2 */
typedef struct libtrace_ospf_lsa_v2_t
{
        uint16_t age;           /**< Time in seconds since LSA originated */
        libtrace_ospf_options_t lsa_options;    /**< Options */
        uint8_t lsa_type;       /**< LSA type */
        struct in_addr ls_id;   /**< Link State ID */
        struct in_addr adv_router; /**< Router that originated this LSA */
        uint32_t seq;           /**< LS sequence number */
        uint16_t checksum;      /**< Checksum */ 
        uint16_t length;        /**< Length of the LSA including LSA header */
} PACKED libtrace_ospf_lsa_v2_t;

/** OSPFv2 Hello Packet */
typedef struct libtrace_ospf_hello_v2_t
{
        struct in_addr mask;    /**< Network mask for this interface */
        uint16_t interval;      /**< Interval between Hello packets (secs) */
        libtrace_ospf_options_t hello_options;  /**< Options */
        uint8_t priority;       /**< Router Priority */
        uint32_t deadint;       /**< Interval before declaring a router down */
        struct in_addr designated;      /**< Designated router for the network */
        struct in_addr backup;  /**< Backup designated router */

        /** Neighbors follow from here, but there can be anywhere from 1 to N
         * neighbors so I can't include that here */
} PACKED libtrace_ospf_hello_v2_t;

/** OSPFv2 Database Description packet */
typedef struct libtrace_ospf_db_desc_v2_t
{
        uint16_t mtu;           /**< Interface MTU */
        libtrace_ospf_options_t db_desc_options;        /**< Options */
#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD8 db_desc_ms:1;      /**< If set, this router is the master */
        LT_BITFIELD8 db_desc_m:1;       /**< If set, more packets to follow */
        LT_BITFIELD8 db_desc_i:1;       /**< If set, this is the first packet in sequence */
        LT_BITFIELD8 zero:5;
#elif BYTE_ORDER == BIG_ENDIAN
        LT_BITFIELD8 zero:5;
        LT_BITFIELD8 db_desc_i:1;       /**< If set, this is the first packet in sequence */
        LT_BITFIELD8 db_desc_m:1;       /**< If set, more packets to follow */
        LT_BITFIELD8 db_desc_ms:1;      /**< If set, this router is the master */
#endif
        uint32_t seq;           /**< Sequence number for DD packets */
} PACKED libtrace_ospf_db_desc_v2_t;

/** OSPF Link State Request Packet */
typedef struct libtrace_ospf_ls_req_t
{
        uint32_t ls_type;       /**< Link State Type */
        uint32_t ls_id;         /**< Link State Id */
        uint32_t advertising_router;    /**< Advertising Router */
} PACKED libtrace_ospf_ls_req_t;

/** OSPF Link State Update Packet */
typedef struct libtrace_ospf_ls_update_t
{
        uint32_t ls_num_adv;    /**< Number of LSAs in this packet */

        /* Followed by LSAs, use API functions to access these */
} PACKED libtrace_ospf_ls_update_t;

/** OSPFv2 AS External LSA Body */
typedef struct libtrace_ospf_as_external_lsa_t
{
        struct in_addr netmask; /**< Netmask for the destination */
#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD8 tos:7;
        LT_BITFIELD8 e:1;       /**< If set, metric is Type 2. Else, Type 1 */
#elif BYTE_ORDER == BIG_ENDIAN
        LT_BITFIELD8 e:1;       /**< If set, metric is Type 2. Else, Type 1 */
        LT_BITFIELD8 tos:7;
#endif
        uint8_t metric_a;       /**< Byte 1 of the Metric field */
        uint8_t metric_b;       /**< Byte 2 of the Metric field */
        uint8_t metric_c;       /**< Byte 3 of the Metric field */
        struct in_addr forwarding;      /**< Forwarding address */
        uint32_t external_tag;          /**< External Route Tag */
} PACKED libtrace_ospf_as_external_lsa_v2_t;

/** OSPFv2 Summary LSA Body */
typedef struct libtrace_ospf_summary_lsa
{
        struct in_addr netmask; /**< Netmask for the destination */
        uint8_t zero;           /**< Always zero */
        uint8_t metric_a;       /**< Byte 1 of the Metric field */
        uint8_t metric_b;       /**< Byte 2 of the Metric field */
        uint8_t metric_c;       /**< Byte 3 of the Metric field */
        
} PACKED libtrace_ospf_summary_lsa_v2_t;

/** OSPFv2 Network LSA Body */
typedef struct libtrace_ospf_network_lsa_t
{
        struct in_addr netmask; /**< Netmask for the network */
        /* Followed by IDs of attached routers */
} PACKED libtrace_ospf_network_lsa_v2_t;

/** OSPFv2 Router Link structure */
typedef struct libtrace_ospf_link_t
{
        struct in_addr link_id;         /**< Object that link connects to */
        struct in_addr link_data;       /**< Link Data field */
        uint8_t type;                   /**< Link Type */
        uint8_t num_tos;                /**< Number of TOS metrics */
        uint16_t tos_metric;            /**< Cost of router link */
} PACKED libtrace_ospf_link_v2_t;

/** OSPFv2 Router LSA */
typedef struct libtrace_ospf_router_lsa_t
{
#if BYTE_ORDER == LITTLE_ENDIAN
        LT_BITFIELD8 b:1;       /**< Area Border Router Flag */
        LT_BITFIELD8 e:1;       /**< External Router Flag */
        LT_BITFIELD8 v:1;       /**< Virtual Endpoint Flag */
        LT_BITFIELD8 zero:5;
#elif BYTE_ORDER == BIG_ENDIAN
        LT_BITFIELD8 zero:5;
        LT_BITFIELD8 v:1;       /**< Virtual Endpoint Flag */
        LT_BITFIELD8 e:1;       /**< External Router Flag */
        LT_BITFIELD8 b:1;       /**< Area Border Router Flag */
#endif
        uint8_t zero2;          /**< Always zero */
        uint16_t num_links;     /**< Number of links in LSA */
} PACKED libtrace_ospf_router_lsa_v2_t;

typedef enum {
        TRACE_OSPF_HELLO = 1,           /**< OSPF Hello */
        TRACE_OSPF_DATADESC = 2,        /**< OSPF Database Description */
        TRACE_OSPF_LSREQ = 3,           /**< OSPF Link State Request */
        TRACE_OSPF_LSUPDATE = 4,        /**< OSPF Link State Update */
        TRACE_OSPF_LSACK = 5            /**< OSPF Link State Acknowledgement */
} libtrace_ospf_types_t;

typedef enum {
        TRACE_OSPF_LS_ROUTER = 1,       /**< OSPF Router LSA */
        TRACE_OSPF_LS_NETWORK = 2,      /**< OSPF Network LSA */
        TRACE_OSPF_LS_SUMMARY = 3,      /**< OSPF Summary LSA */
        TRACE_OSPF_LS_ASBR_SUMMARY = 4, /**< OSPF Summary LSA (ASBR) */
        TRACE_OSPF_LS_EXTERNAL = 5      /**< OSPF AS External LSA */
} libtrace_ospf_ls_types_t;

/** A local definition of an SLL header */
typedef struct libtrace_sll_header_t {
        uint16_t pkttype;               /**< Packet type */
        uint16_t hatype;                /**< Link-layer address type */
        uint16_t halen;                 /**< Link-layer address length */
        unsigned char addr[8];          /**< Link-layer address */
        uint16_t protocol;              /**< Protocol */
} libtrace_sll_header_t;


/* SLL packet types */

/** Packet was addressed for the local host */
#define TRACE_SLL_HOST          0
/** Packet was addressed for a broadcast address */
#define TRACE_SLL_BROADCAST     1
/** Packet was addressed for a multicast address */
#define TRACE_SLL_MULTICAST     2
/** Packet was addressed for another host but was captured by a promiscuous
 * device */
#define TRACE_SLL_OTHERHOST     3
/** Packet originated from the local host */
#define TRACE_SLL_OUTGOING      4


#ifdef WIN32
#pragma pack(pop)
#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);

/** Causes a libtrace reader to stop blocking whilst waiting on new packets
 * and immediately return EOF.
 *
 * This function is useful if you are handling signals within your libtrace
 * program. If a live source is not receiving any packets (or they are being
 * filtered), a call to trace_read_packet will result in an infinite loop as
 * it will block until a packet is received. Normally, a SIGINT would cause the
 * program to end and thus break the loop, but if you are handling the signal
 * yourself then that signal will never reach libtrace.
 *
 * Instead this function sets a global variable within libtrace that will 
 * cause a blocking live capture to break on the next internal timeout, 
 * allowing control to be returned to the user and their own signal handling
 * to kick in.
 */
DLLEXPORT void trace_interrupt(void); 

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

/** Takes a uri and splits it into a format and uridata component. 
 * @param uri           The uri to be parsed
 * @param [out] format  A pointer that will be updated to point to an allocated 
 *                      string holding the format component of the URI
 * @return NULL if an error occured, otherwise return a pointer to the uridata 
 * component
 *
 * @note The format component is strdup'd by this function, so be sure to free
 * it when you are done with the split URI. Similarly, do not pass a pointer
 * to an allocated string into this function as the 'format' parameter, as
 * that memory will be leaked and replaced with the strdup'd format.
 */
DLLEXPORT const char *trace_parse_uri(const char *uri, char **format);

/** Create an input trace from a URI
 * 
 * @param uri A valid libtrace URI to be opened
 * @return An opaque pointer to a libtrace_t
 *
 * Some valid URI's are:
 *  - erf:/path/to/erf/file
 *  - erf:-  (stdin)
 *  - dag:/dev/dagcard                  
 *  - pcapint:pcapinterface                (eg: pcap:eth0)
 *  - pcap:/path/to/pcap/file
 *  - pcap:-
 *  - rt:hostname
 *  - rt:hostname:port
 *
 *  If an error occured when attempting to open the trace file, a
 *  trace is still returned so trace_is_err() should be called to find out
 *  if an error occured. The trace is created in the configuration state, you 
 *  must call trace_start before attempting to read packets from the trace.
 */
DLLEXPORT libtrace_t *trace_create(const char *uri);

/** Creates a "dummy" trace file that has only the format type set.
 *
 * @param uri A valid (but fake) URI indicating the format of the dummy trace that is to be created.
 * @return An opaque pointer to a (sparsely initialised) libtrace_t
 *
 * Only the format portion of the uri parameter matters - the 'file' being
 * opened does not have to exist.
 *
 * @note IMPORTANT: Do not attempt to call trace_read_packet or other such 
 * functions with the dummy trace. Its intended purpose is to provide access
 * to the format functions where the original trace may no longer exist or is
 * not the correct format, e.g. reading ERF packets from an RT input.
 */
DLLEXPORT 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 An opaque pointer to a libtrace_output_t
 *
 * Valid URIs include:
 *  - erf:/path/to/erf/file
 *  - pcap:/path/to/pcap/file
 *
 *  If an error occured when attempting to open the output trace, a trace is 
 *  still returned but trace_errno will be set. Use trace_is_err_out() and 
 *  trace_perror_output() to get more information.
 */
DLLEXPORT libtrace_out_t *trace_create_output(const char *uri);

/** Start an input trace
 * @param libtrace      The trace to start
 * @return 0 on success, -1 on failure
 *
 * This does the actual work of starting the input trace and applying
 * all the config options.  This may fail, returning -1. The libtrace error
 * handling functions can be used to get more information about what 
 * specifically went wrong.
 */
DLLEXPORT int trace_start(libtrace_t *libtrace);

/** Pauses an input trace
 * @param libtrace      The trace to pause
 * @return 0 on success, -1 on failure
 *
 * This stops an input trace that is in progress and returns you to the 
 * configuration state.  Any packets that arrive on a live capture after 
 * trace_pause() has been called will be discarded.  To resume the trace, call 
 * trace_start().
 */
DLLEXPORT int trace_pause(libtrace_t *libtrace);

/** Start an output trace
 * @param libtrace      The trace to start
 * @return 0 on success, -1 on failure
 *
 * This does the actual work with starting a trace capable of writing packets.  
 * This generally creates the output file.
 */
DLLEXPORT int trace_start_output(libtrace_out_t *libtrace);

/** Valid configuration options for input traces */
typedef enum {
        /** Maximum number of bytes to be captured for any given packet */
        TRACE_OPTION_SNAPLEN,   

        /** If enabled, places a live capture interface into promiscuous mode */
        TRACE_OPTION_PROMISC,   

        /** Apply this filter to all packets read from this trace */
        TRACE_OPTION_FILTER,    

        /** Defines the frequency of meta-data reporting, e.g. DUCK packets */
        TRACE_OPTION_META_FREQ, 

        /** If enabled, the libtrace event API will ignore time gaps between
         * packets when reading from a trace file */
        TRACE_OPTION_EVENT_REALTIME
} 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
 */
DLLEXPORT int trace_config(libtrace_t *libtrace,
                trace_option_t option,
                void *value);

/** Valid compression types 
 * Note, this must be kept in sync with WANDIO_COMPRESS_* numbers in wandio.h
 */ 
typedef enum {
        TRACE_OPTION_COMPRESSTYPE_NONE = 0, /**< No compression */
        TRACE_OPTION_COMPRESSTYPE_ZLIB = 1, /**< GZip Compression */
        TRACE_OPTION_COMPRESSTYPE_BZ2  = 2, /**< BZip2 Compression */
        TRACE_OPTION_COMPRESSTYPE_LZO  = 3  /**< LZO Compression */
} trace_option_compresstype_t;

/** Valid configuration options for output traces */
typedef enum {
        /** File flags to use when opening an output file, e.g. O_APPEND */
        TRACE_OPTION_OUTPUT_FILEFLAGS,
        /** Compression level: 0 = no compression, 1 = faster compression,
         * 9 = better compression */
        TRACE_OPTION_OUTPUT_COMPRESS,
        /** Compression type, see trace_option_compresstype_t */
        TRACE_OPTION_OUTPUT_COMPRESSTYPE
} 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
 */
DLLEXPORT int trace_config_output(libtrace_out_t *libtrace, 
                trace_option_output_t option,
                void *value
                );

/** Close an input trace, freeing up any resources it may have been using
 *
 * @param trace         The input trace to be destroyed
 *
 */
DLLEXPORT void trace_destroy(libtrace_t *trace);

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

/** Close an output trace, freeing up any resources it may have been using
 * @param trace         The output trace to be destroyed
 */
DLLEXPORT void trace_destroy_output(libtrace_out_t *trace);

/** Check (and clear) the current error state of an input trace
 * @param trace         The input trace to check the error state on
 * @return The current error status and message
 *
 * This reads and returns the current error state and sets the current error 
 * to "no error".
 */
DLLEXPORT libtrace_err_t trace_get_err(libtrace_t *trace);

/** Indicate if there has been an error on an input trace
 * @param trace         The input trace to check the error state on
 * @return true if an error has occurred, false otherwise
 *
 * @note This does not clear the error status, and only returns true or false.
 */
DLLEXPORT bool trace_is_err(libtrace_t *trace);

/** Outputs the error message for an input trace to stderr and clear the error 
 * status.
 * @param trace         The input trace with the error to output
 * @param msg           The message to prepend to the error
 *
 * This function does clear the error status.
 */
DLLEXPORT void trace_perror(libtrace_t *trace, const char *msg,...) PRINTF(2,3);

/** Checks (and clears) the current error state for an output trace
 * @param trace         The output trace to check the error state on
 * @return The current error status and message
 * 
 * This reads and returns the current error state and sets the current error 
 * to "no error".
 */
DLLEXPORT libtrace_err_t trace_get_err_output(libtrace_out_t *trace);

/** Indicates if there is an error on an output trace
 * @param trace         The output trace to check the error state on
 * @return true if an error has occurred, false otherwise.
 *
 * This does not clear the error status, and only returns true or false.
 */
DLLEXPORT bool trace_is_err_output(libtrace_out_t *trace);

/** Outputs the error message for an output trace to stderr and clear the error
 * status.
 * @param trace         The output trace with the error to output
 * @param msg           The message to prepend to the error
 * This function does clear the error status.
 */
DLLEXPORT void trace_perror_output(libtrace_out_t *trace, const char *msg,...)
        PRINTF(2,3);

/** Returns the number of packets observed on an input trace. 
 * Includes the number of packets counted as early as possible, before
 * filtering, and includes dropped packets.
 *
 * @param trace         The input trace to examine
 * @returns The number of packets seen at the capture point before filtering.
 *
 * If the number is not known, this function will return UINT64_MAX
 */
DLLEXPORT
uint64_t trace_get_received_packets(libtrace_t *trace);

/** Returns the number of packets that were captured, but discarded for not
 * matching a provided filter. 
 *
 * @param trace         The input trace to examine
 * @returns The number of packets that were successfully captured, but filtered
 *
 * If the number is not known, this function will return UINT64_MAX
 */
DLLEXPORT
uint64_t trace_get_filtered_packets(libtrace_t *trace);

/** Returns the number of packets that have been dropped on an input trace due 
 * to lack of buffer space on the capturing device.
 *
 * @param trace         The input trace to examine
 * @returns The number of packets captured, but dropped due to buffer overruns
 *
 * If the number is not known, this function will return UINT64_MAX
 */
DLLEXPORT
uint64_t trace_get_dropped_packets(libtrace_t *trace);

/** Returns the number of packets that have been read from the input trace using
 * trace_read_packet().
 *
 * @param trace         The input trace to examine
 * @returns The number of packets that have been read by the libtrace user.
 *
 * If the number is not known, this function will return UINT64_MAX
 */
DLLEXPORT
uint64_t trace_get_accepted_packets(libtrace_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
 */
DLLEXPORT libtrace_packet_t *trace_create_packet(void);

/** Copy a packet object
 * @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 will be stored using memory owned by the device which
 * may be a limited resource. Copying the packet will ensure that the packet
 * is now stored in memory owned and managed by libtrace.
 */
DLLEXPORT libtrace_packet_t *trace_copy_packet(const libtrace_packet_t *packet);

/** Destroy a packet object
 * @param packet        The packet to be destroyed
 *
 */
DLLEXPORT void trace_destroy_packet(libtrace_packet_t *packet);


/** Read the next packet from an input trace 
 *
 * @param trace         The libtrace opaque pointer for the input trace
 * @param packet        The packet opaque pointer
 * @return 0 on EOF, negative value on error, number of bytes read when successful.
 *
 * @note The number of bytes read is usually (but not always) the same as
 * trace_get_framing_length()+trace_get_capture_length() depending on the
 * trace format.
 *
 * @note The trace must have been started with trace_start before calling
 * this function
 *
 * @note When reading from a live capture, this function will block until a
 * packet is observed on the capture interface. The libtrace event API 
 * (e.g. trace_event()) should be used if non-blocking operation is required.
 */
DLLEXPORT 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,     /**< Wait on the given file descriptor */
        TRACE_EVENT_SLEEP,      /**< Sleep for the given amount of time */
        TRACE_EVENT_PACKET,     /**< Packet has been read from input trace */
        TRACE_EVENT_TERMINATE   /**< End of input 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) */
        
        /** If the event is IOWAIT, the file descriptor to wait on */
        int fd;                
        /** If the event is SLEEP, the amount of time to sleep for in seconds */
        double seconds;        
        /** If the event is PACKET, the value returned by trace_read_packet() */
        int size; 
} libtrace_eventobj_t;

/** Processes the next libtrace event from an input trace.
 * @param trace The libtrace opaque pointer for the input trace
 * @param packet The libtrace_packet opaque pointer to use for reading packets
 * @return A libtrace_event struct containing the event type and details of the event.
 *
 * Type can be:
 *  TRACE_EVENT_IOWAIT  Waiting on I/O on a file descriptor
 *  TRACE_EVENT_SLEEP   Wait a specified amount of time for the next event
 *  TRACE_EVENT_PACKET  Packet was read from the trace
 *  TRACE_EVENT_TERMINATE Trace terminated (perhaps with an error condition)
 */
DLLEXPORT 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 for the output trace
 * @param packet        The packet opaque pointer of the packet to be written
 * @return The number of bytes written out, if zero or negative then an error has occured.
 */
DLLEXPORT int trace_write_packet(libtrace_out_t *trace, libtrace_packet_t *packet);

/** Gets the capture format for a given packet.
 * @param packet        The packet to get the capture format for.
 * @return The capture format of the packet
 *
 * @note Due to ability to convert packets between formats relatively easily
 * in Libtrace, the format of the packet right now may not be the format that
 * the packet was originally captured with.
 */
DLLEXPORT 
enum base_format_t trace_get_format(struct libtrace_packet_t *packet);

/** Construct a libtrace packet from a buffer containing the packet payload.
 * @param[in,out] packet        Libtrace Packet object to update with the new 
 *                              data.
 * @param linktype              The linktype of the packet data.
 * @param[in] data              The packet data (including linklayer).
 * @param len                   Length of packet data provided in the buffer.
 *
 * @note The constructed packet will be in the PCAP format.
 *
 * @note To be useful, the provided buffer must start with the layer 2 header
 * (or a metadata header, if desired).
 */
DLLEXPORT
void trace_construct_packet(libtrace_packet_t *packet,
                libtrace_linktype_t linktype, const void *data, uint16_t len);

/*@}*/

/** @name Protocol decodes
 * These functions locate and return a pointer to various headers inside a
 * packet
 * 
 * A packet is divided up into several "layers.":
 *
 * @li Framing header -- This is the header provided by the capture format 
 * itself rather than anything that was sent over the network. This provides
 * basic details about the packet record including capture lengths, wire 
 * lengths, timestamps, direction information and any other metadata that is 
 * part of the capture format.  
 * 
 * @li Metadata header (optional) -- A header containing metadata about a 
 * packet that was captured, but the metadata was not transmitted over the 
 * wire.  Some examples include RadioTap and Linux_sll headers.  This can be 
 * retrieved by trace_get_packet_meta(), or skipped using 
 * trace_get_payload_from_meta(). There may be multiple "metadata" headers on 
 * a packet.
 *
 * @li Layer 2/Link layer/Datalink header -- This can be retrieved by 
 * trace_get_layer2(), or skipped using trace_get_payload_from_layer2().
 *
 * @li Layer 3/IP/IPv6 -- This can be retrieved by trace_get_layer3().  As a 
 * convenience trace_get_ip()/trace_get_ip6() can be used to find an IPv4/IPv6 
 * header.
 *
 * @li Layer 5/transport -- These are protocols carried in IPv4/IPv6 frames. 
 * These can be retrieved using trace_get_transport().
 * 
 * @{
 */


/** Gets a pointer to the first byte of the packet as it was captured and
 * returns its corresponding linktype and capture length.
 *
 * Use this function instead of the deprecated trace_get_link().
 *
 * @param packet The packet to get the buffer from
 * @param[out] linktype The linktype of the returned pointer
 * @param[out] remaining The capture length (the number of captured bytes from
 * the returned pointer)
 * @return A pointer to the first byte of the packet
 */
DLLEXPORT void *trace_get_packet_buffer(const libtrace_packet_t *packet,
                libtrace_linktype_t *linktype, uint32_t *remaining);

/** Get a pointer to the link layer for a given packet
 * @param packet        The packet to get the link layer for
 *
 * @return A pointer to the link layer, or NULL if there is no link layer
 *
 * @deprecated This function is deprecated: Use trace_get_packet_buffer() or
 * one of the trace_get_layer*() functions instead.
 * @note You should call trace_get_link_type to find out what type of link
 * layer has been returned to you.
 */
DLLEXPORT SIMPLE_FUNCTION DEPRECATED
void *trace_get_link(const libtrace_packet_t *packet);

/** Get a pointer to the IPv4 header (if any) for a given packet
 * @param packet        The packet to get the IPv4 header for
 *
 * @return A pointer to the IPv4 header, or NULL if there is no IPv4 header
 *
 * If a partial IP header is present, i.e. the packet has been truncated before
 * the end of the IP header, this function will return NULL.
 *
 * You should consider using \ref trace_get_layer3 instead of this function.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_ip_t *trace_get_ip(libtrace_packet_t *packet);

/** get a pointer to the IPv6 header (if any)
 * @param packet        The packet to get the IPv6 header for
 *
 * @return A pointer to the IPv6 header, or NULL if there is no IPv6 header
 *
 * If a partial IPv6 header is present, i.e. the packet has been truncated
 * before the end of the IP header, this function will return NULL.
 *
 * You should consider using \ref trace_get_layer3 instead of this function.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_ip6_t *trace_get_ip6(libtrace_packet_t *packet);

/** Return a pointer to the first metadata header in a packet, if present.
 *
 * This function takes a pointer to a libtrace packet and if any metadata
 * headers exist, returns a pointer to the first one, along with its
 * corresponding linktype. 
 *
 * If no metadata headers exist in the packet, NULL is returned.
 *
 * A metadata header is a header that was prepended by the capturing device,
 * such as a Linux SLL header, or a Radiotap wireless monitoring header.
 * Subsequent metadata headers may be accessed with the
 * trace_get_payload_from_meta(...) function. 
 *
 * @param packet The libtrace packet
 * @param[out] linktype The linktype of the returned metadata header
 * @param[out] remaining The number of bytes captured after the returned
 * pointer.
 * @return A pointer to the first metadata header, or NULL if there are no
 * metadata headers present.
 *
 * remaining may be NULL, however linktype must be provided.
 */
DLLEXPORT void *trace_get_packet_meta(const libtrace_packet_t *packet,
                libtrace_linktype_t *linktype,
                uint32_t *remaining);

/** Returns the payload of a metadata header.
 * 
 * This function takes a pointer to the start of a metadata header (either
 * obtained via trace_get_packet_meta(...) or by a previous call to
 * trace_get_payload_from_meta(...)) along with its corresponding linktype and
 * returns the payload, i.e. the next header. It will also update the linktype
 * parameter to indicate the type of payload.
 *  
 * If the linktype indicates that the header passed in is not a metadata
 * header, the function returns NULL to indicate this. The linktype remains
 * unchanged in this case.
 *
 * This function allows the user to iterate through metadata headers which are
 * sometimes present before the actual packet as it was received on the wire.
 * Examples of metadata headers include the Linux SLL header and the Radiotap
 * wireless monitoring header.
 *
 * If the metadata header passed into this function is truncated, this 
 * function will return NULL, and remaining will be set to 0.
 *
 * If there are 0 bytes of payload following the provided metadata header, the 
 * function will return a pointer to where the header would otherwise be and 
 * remaining will be 0.
 *
 * Therefore, be sure to check the value of remaining after calling this
 * function!
 *
 * @param[in] meta A pointer to a metadata header
 * @param[in,out] linktype The linktype of meta (updated to indicate the
 * linktype of the returned header if applicable).
 * @param[in,out] remaining The number of bytes after the meta pointer.
 * @return A pointer to the payload of the metadata header. If meta is not a
 * pointer to a metadata header, NULL is returned and linktype remains
 * unchanged.
 *
 * All parameters are mandatory. 
 */
DLLEXPORT void *trace_get_payload_from_meta(const void *meta,
                libtrace_linktype_t *linktype,
                uint32_t *remaining);


/** Get a pointer to the layer 2 header. Generally this is the first byte of the
 * packet as it was seen on the wire.
 * 
 * This function takes a libtrace packet and skips over any metadata headers if
 * present (such as Linux SLL or Radiotap) and returns a pointer to the first
 * byte of the packet that was actually received by the network interface.
 *
 * @param packet The libtrace packet to find the layer 2 header for
 * @param[out] linktype The linktype of the returned layer 2 header
 * @param[out] remaining The number of bytes left in the packet after the
 * returned pointer.
 * @return A pointer to the first byte of the packet as it was seen on the
 * wire. If no layer 2 header is present, this function will return NULL.
 *
 * remaining may be NULL, otherwise it will be filled in by the function.
 */
DLLEXPORT void *trace_get_layer2(const libtrace_packet_t *packet,
                libtrace_linktype_t *linktype,
                uint32_t *remaining);

/** Gets a pointer to the next header following a layer 2 header
 *
 * @param l2                    The pointer to the current layer 2 header
 * @param linktype              The type of the layer 2 header
 * @param[out] ethertype        An optional output variable of the ethernet type of the new header
 * @param[in,out] remaining     Updated with the number of captured bytes 
                                remaining
 *
 * @return A pointer to the header following the provided layer 2 header, or 
 * NULL if no subsequent header is present.
 *
 * Remaining must point to the number of bytes captured from the layer 2 header
 * and beyond.  It will be decremented by the number of bytes skipped to find
 * the payload.
 *
 * If the layer 2 header is complete but there are zero bytes of payload after 
 * the end of the header, a pointer to where the payload would be is returned 
 * and remaining will be set to 0.  If the layer 2 header is incomplete 
 * (truncated), then NULL is returned and remaining will be set to 0. 
 * Therefore, it is very important to check the value of remaining after
 * calling this function. 
 *
 */
DLLEXPORT void *trace_get_payload_from_layer2(void *l2,
                libtrace_linktype_t linktype,
                uint16_t *ethertype,
                uint32_t *remaining);


/** Get a pointer to the layer 3 (e.g. IP) header.
 * @param packet  The libtrace packet to find the layer 3 header for
 * @param[out] ethertype The ethertype of the layer 3 header
 * @param[out] remaining The amount of captured data remaining in the packet starting from the returned pointer, i.e. including the layer 3 header.
 *
 * @return A pointer to the layer 3 header. If no layer 3 header is present in
 * the packet, NULL is returned. If the layer 3 header is truncated, a valid 
 * pointer will still be returned so be sure to check the value of remaining
 * before attempting to process the returned header.
 *
 * remaining may be NULL, otherwise it will be set to the number of captured
 * bytes after the pointer returned.
 */
DLLEXPORT 
void *trace_get_layer3(const libtrace_packet_t *packet,
                uint16_t *ethertype, uint32_t *remaining);

/** Calculates the expected IP checksum for a packet.
 * @param packet        The libtrace packet to calculate the checksum for
 * @param[out] csum     The checksum that is calculated by this function. This
 *                      may not be NULL.
 * 
 * @return A pointer to the original checksum field within the IP
 * header. If the checksum field is not present in the packet, NULL is returned.
 *
 * @note The return value points to the checksum that exists within the current
 * packet. The value in csum is the value that the checksum should be, given
 * the current packet contents.  
 *
 * @note This function involves the use of a memcpy, so be careful about
 * calling it excessively if performance is a concern for you.
 * 
 * New in libtrace 3.0.17
 */
DLLEXPORT uint16_t *trace_checksum_layer3(libtrace_packet_t *packet, 
                uint16_t *csum);

/** Calculates the expected checksum for the transport header in a packet.
 * @param packet        The libtrace packet to calculate the checksum for
 * @param[out] csum     The checksum that is calculated by this function. This
 *                      may not be NULL.
 * 
 * @return A pointer to the original checksum field within the transport 
 * header. If the checksum field is not present in the packet, NULL is returned.
 *
 * @note The return value points to the checksum that exists within the current
 * packet. The value in csum is the value that the checksum should be, given
 * the current packet contents.  
 *
 * @note This function involves the use of a memcpy, so be careful about
 * calling it excessively if performance is a concern for you.
 * 
 * @note Because transport checksums are calculated across the entire payload,
 * truncated packets will result in NULL being returned.
 *
 * This function will determine the appropriate checksum for whatever transport
 * layer header is present in the provided packet. At this stage, this only
 * currently works for TCP, UDP and ICMP packets.
 *
 * Be wary of TCP checksum offloading if you are examining the checksum of
 * packets captured on the same host that generated them!
 *
 * New in libtrace 3.0.17
 */
DLLEXPORT uint16_t *trace_checksum_transport(libtrace_packet_t *packet,
                uint16_t *csum);

/** Gets a pointer to the transport layer header (if any)
 * @param packet   The libtrace packet to find the transport header for
 * @param[out] proto    The protocol present at the transport layer.
 * @param[out] remaining The amount of captured data remaining in the packet 
 * starting from the returned pointer, i.e. including the transport header.
 *
 * @return A pointer to the transport layer header. If no transport header is
 * present in the packet, NULL is returned. If the transport header is 
 * truncated, a valid pointer will still be returned so be sure to check the
 * value of remaining before attempting to process the returned header.
 *
 * remaining may be NULL, otherwise it will be set to the number of captured
 * bytes after the returned pointer.
 *
 * @note proto may be NULL if proto is unneeded.
 */
DLLEXPORT void *trace_get_transport(const libtrace_packet_t *packet, 
                uint8_t *proto, uint32_t *remaining);

/** Gets a pointer to the payload following an IPv4 header
 * @param ip            The IPv4 Header
 * @param[out] proto    The protocol of the header following the IPv4 header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the transport layer header, or NULL if no subsequent 
 * header is present.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the IPv4 header (including the
 * IPv4 header itself).
 *
 * remaining will be decremented by the size of the IPv4 header (including any 
 * options). If the IPv4 header is complete but there are zero bytes of payload
 * after the IPv4 header, a pointer to where the payload would be is returned 
 * and remaining will be set to 0.  If the IPv4 header is incomplete, NULL will
 * be returned and remaining will be set to 0. Therefore, it is very important
 * to check the value of remaining after calling this function.
 *
 * proto may be NULL, in which case it won't be updated.
 *
 * @note This is similar to trace_get_transport_from_ip in libtrace2
 */
DLLEXPORT void *trace_get_payload_from_ip(libtrace_ip_t *ip, uint8_t *proto,
                uint32_t *remaining);

/** Gets a pointer to the payload following an IPv6 header
 * @param ipptr         The IPv6 Header
 * @param[out] proto    The protocol of the header following the IPv6 header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the transport layer header, or NULL if no subsequent 
 * header is present.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the IPv6 header (including the
 * IPv6 header itself).
 *
 * remaining will be decremented by the size of the IPv6 header (including any 
 * options). If the IPv6 header is complete but there are zero bytes of payload
 * after the IPv6 header, a pointer to where the payload would be is returned 
 * and remaining will be set to 0.  If the IPv6 header is incomplete, NULL will
 * be returned and remaining will be set to 0. Therefore, it is very important
 * to check the value of remaining after calling this function.
 *
 * proto may be NULL, in which case it won't be updated.
 *
 */
DLLEXPORT void *trace_get_payload_from_ip6(libtrace_ip6_t *ipptr,
                uint8_t *proto, uint32_t *remaining);

/** Gets a pointer to the payload following a link header
 * @param linkptr       A pointer to the link layer header
 * @param linktype      The linktype of the link header being examined
 * @param[out] type     An output variable for the ethernet type
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the header following the link header, or NULL if no
 * subsequent header is present.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the link header (including the
 * link header itself). remaining will be updated to contain the number of 
 * bytes remaining after the link header has been skipped.
 *
 * @deprecated This function is deprecated: you should be using 
 * trace_get_payload_from_layer2() or trace_get_payload_from_meta() instead.
 *
 */
DLLEXPORT void *trace_get_payload_from_link(void *linkptr,
                libtrace_linktype_t linktype, 
                uint16_t *type, uint32_t *remaining);

/** Gets a pointer to the payload following an 802.1q (VLAN) header.
 * @param vlan      A pointer to the VLAN header
 * @param[out] type  The ethernet type, replaced with the VLAN ether type
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the header beyond the VLAN header, if one is present.
 * Otherwise, returns NULL.  
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the VLAN header (including the
 * VLAN header itself). remaining will be updated to contain the number of 
 * bytes remaining after the VLAN header has been skipped.
 *
 * If the VLAN header is complete but there are zero bytes of payload after 
 * the VLAN header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the VLAN header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * type will be set to the ethertype of the VLAN payload. This parameter is not
 * mandatory, but is highly recommended.
 *
 */
DLLEXPORT void *trace_get_payload_from_vlan(
                void *vlan, uint16_t *type, uint32_t *remaining);

/** Gets a pointer to the payload following an MPLS header.
 * @param mpls      A pointer to the MPLS header
 * @param[out] type  The ethernet type, replaced by the ether type of the
 * returned header - 0x0000 if an Ethernet header is returned
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the header beyond the MPLS label, if one is present. 
 * Will return NULL if there is not enough bytes remaining to skip past the 
 * MPLS label.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the MPLS header (including the
 * MPLS header itself). remaining will be updated to contain the number of 
 * bytes remaining after the MPLS header has been skipped.
 *
 * If the MPLS header is complete but there are zero bytes of payload after 
 * the MPLS header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the MPLS header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * type will be set to the ethertype of the MPLS payload. This parameter is
 * mandatory - it may not be NULL.
 *
 * @note This function will only remove one MPLS label at a time - the type
 * will be set to 0x8847 if there is another MPLS label following the one
 * skipped by this function.
 *
 */
DLLEXPORT void *trace_get_payload_from_mpls(
                void *mpls, uint16_t *type, uint32_t *remaining);

/** Gets a pointer to the payload following a PPPoE header
 * @param pppoe      A pointer to the PPPoE header
 * @param[out] type  The ethernet type, replaced by the ether type of the
 * returned header - 0x0000 if an Ethernet header is returned
 * @param[in,out] remaining  Updated with the number of captured bytes remaining
 *
 * @return A pointer to the header beyond the PPPoE header. NOTE that this
 * function will also skip over the PPP header that will immediately follow
 * the PPPoE header. This function will return NULL if there are not enough
 * bytes remaining to skip past both the PPPoE and PPP headers.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the PPPoE header (including the
 * PPPoE header itself). remaining will be updated to contain the number of 
 * bytes remaining after the PPPoE and PPP headers have been removed.
 *
 * If the PPPoE and PPP headers are complete but there are zero bytes of 
 * payload after the PPP header, a pointer to where the payload would be is 
 * returned and remaining will be set to 0.  If the PPPoE or PPP header is 
 * incomplete, NULL will be returned and remaining will be set to 0. Therefore, 
 * it is important to check the value of remaining after calling this function.
 *
 * type will be set to the ether type of the PPP payload. This parameter is
 * mandatory - it may not be NULL.
 *
 */
DLLEXPORT void *trace_get_payload_from_pppoe(
                void *pppoe, uint16_t *type, uint32_t *remaining);

/** Gets a pointer to the payload following a TCP header
 * @param tcp           A pointer to the TCP header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the TCP payload, or NULL if the TCP header is truncated.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the TCP header (including the
 * TCP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the TCP header has been skipped.
 *
 * If the TCP header is complete but there are zero bytes of payload after 
 * the TCP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the TCP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 */
DLLEXPORT void *trace_get_payload_from_tcp(libtrace_tcp_t *tcp, 
                uint32_t *remaining);

/** Gets a pointer to the payload following a UDP header
 * @param udp           A pointer to the UDP header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the UDP payload, or NULL if the UDP header is truncated.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the UDP header (including the
 * UDP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the UDP header has been skipped.
 *
 * If the UDP header is complete but there are zero bytes of payload after 
 * the UDP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the UDP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 */
DLLEXPORT void *trace_get_payload_from_udp(libtrace_udp_t *udp, uint32_t *remaining);

/** Gets a pointer to the payload following a ICMP header
 * @param icmp           A pointer to the ICMP header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the ICMP payload, or NULL if the ICMP header is 
 * truncated.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the ICMP header (including the
 * ICMP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the ICMP header has been skipped.
 *
 * If the ICMP header is complete but there are zero bytes of payload after 
 * the ICMP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the ICMP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * @note In the case of some ICMP messages, the payload may be the IP header
 * from the packet that triggered the ICMP message. 
 *
 */
DLLEXPORT void *trace_get_payload_from_icmp(libtrace_icmp_t *icmp, 
                uint32_t *remaining);

/** Gets a pointer to the payload following a ICMPv6 header
 * @param icmp           A pointer to the ICMPv6 header
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the ICMPv6 payload, or NULL if the ICMPv6 header is 
 * truncated.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the ICMPv6 header (including the
 * ICMP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the ICMPv6 header has been skipped.
 *
 * If the ICMPv6 header is complete but there are zero bytes of payload after 
 * the header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the ICMPv6 header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * @note In the case of some ICMPv6 messages, the payload may be the IP header
 * from the packet that triggered the ICMP message. 
 *
 */
DLLEXPORT void *trace_get_payload_from_icmp6(libtrace_icmp6_t *icmp, 
                uint32_t *remaining);

/** Get a pointer to the TCP header (if present)
 * @param packet        The packet to get the TCP header from
 *
 * @return A pointer to the TCP header, or NULL if there is not a complete TCP
 * header present in the packet.
 *
 * This is a short-cut function enabling quick and easy access to the TCP
 * header if that is all you care about. However, we recommend the use of the
 * more generic trace_get_transport() function instead.
 *
 * @note Unlike trace_get_transport(), this function will return NULL if the
 * TCP header is incomplete or truncated.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_tcp_t *trace_get_tcp(libtrace_packet_t *packet);

/** Get a pointer to the TCP header following an IPv4 header (if present)
 * @param ip            The IP header to find the subsequent TCP header for
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the TCP header, or NULL if no TCP header is present in 
 * the packet.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the IP header (including the
 * IP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the IP header has been skipped.
 *
 * If the IP header is complete but there are zero bytes of payload after 
 * the IP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the IP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * @note This function is rather redundant now that the layer 3 header is
 * cached. There should be no performance advantage for the user to call this
 * function over just calling trace_get_transport().
 *
 * @note The last parameter has changed from libtrace2
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_tcp_t *trace_get_tcp_from_ip(libtrace_ip_t *ip, uint32_t *remaining);

/** Get a pointer to the UDP header (if present)
 * @param packet        The packet to get the UDP header from
 *
 * @return A pointer to the UDP header, or NULL if there is not a complete UDP
 * header present in the packet.
 *
 * This is a short-cut function enabling quick and easy access to the UDP
 * header if that is all you care about. However, we recommend the use of the
 * more generic trace_get_transport() function instead.
 *
 * @note Unlike trace_get_transport(), this function will return NULL if the
 * UDP header is incomplete or truncated.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_udp_t *trace_get_udp(libtrace_packet_t *packet);

/** Get a pointer to the UDP header following an IPv4 header (if present)
 * @param ip            The IP header to find the subsequent UDP header for
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the UDP header, or NULL if no UDP header is present in 
 * the packet.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the IP header (including the
 * IP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the IP header has been skipped.
 *
 * If the IP header is complete but there are zero bytes of payload after 
 * the IP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the IP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * @note This function is rather redundant now that the layer 3 header is
 * cached. There should be no performance advantage for the user to call this
 * function over just calling trace_get_transport().
 *
 * @note The last parameter has changed from libtrace2
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_udp_t *trace_get_udp_from_ip(libtrace_ip_t *ip,uint32_t *remaining);

/** Get a pointer to the ICMP header (if present)
 * @param packet        The packet to get the ICMP header from
 *
 * @return A pointer to the ICMP header, or NULL if there is not a complete 
 * ICMP header present in the packet.
 *
 * This is a short-cut function enabling quick and easy access to the ICMP
 * header if that is all you care about. However, we recommend the use of the
 * more generic trace_get_transport() function instead.
 *
 * @note Unlike trace_get_transport(), this function will return NULL if the
 * ICMP header is incomplete or truncated.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_icmp_t *trace_get_icmp(libtrace_packet_t *packet);

/** Get a pointer to the ICMPv6 header (if present)
 * @param packet        The packet to get the ICMPv6 header from
 *
 * @return A pointer to the ICMPv6 header, or NULL if there is not a complete 
 * ICMP header present in the packet.
 *
 * This is a short-cut function enabling quick and easy access to the ICMPv6
 * header if that is all you care about. However, we recommend the use of the
 * more generic trace_get_transport() function instead.
 *
 * @note Unlike trace_get_transport(), this function will return NULL if the
 * ICMPv6 header is incomplete or truncated.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_icmp6_t *trace_get_icmp6(libtrace_packet_t *packet);

/** Get a pointer to the ICMP header following an IPv4 header (if present)
 * @param ip            The IP header to find the subsequent ICMP header for
 * @param[in,out] remaining Updated with the number of captured bytes remaining
 *
 * @return A pointer to the ICMP header, or NULL if no UDP header is present in 
 * the packet.
 *
 * When calling this function, remaining must contain the number of captured
 * bytes remaining in the packet starting from the IP header (including the
 * IP header itself). remaining will be updated to contain the number of 
 * bytes remaining after the IP header has been skipped.
 *
 * If the IP header is complete but there are zero bytes of payload after 
 * the IP header, a pointer to where the payload would be is returned and 
 * remaining will be set to 0.  If the IP header is incomplete, NULL will be 
 * returned and remaining will be set to 0. Therefore, it is important to check
 * the value of remaining after calling this function.
 *
 * @note This function is rather redundant now that the layer 3 header is
 * cached. There should be no performance advantage for the user to call this
 * function over just calling trace_get_transport().
 *
 * @note The last parameter has changed from libtrace2
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_icmp_t *trace_get_icmp_from_ip(libtrace_ip_t *ip,uint32_t *remaining);

/** Get a pointer to the OSPF header (if present)
 * @param packet        The packet to get the OSPF header from
 * @param[out] version  The OSPF version number
 * @param[out] remaining        Updated with the number of captured bytes remaining
 * @return A pointer to the start of the OSPF header or NULL if there is no 
 * complete OSPF header present in the packet
 *
 * This is a short-cut function enabling quick and easy access to the OSPF
 * header. If you only care about the OSPF header, this function may be useful
 * but we otherwise recommend the use of the more generic trace_get_transport()
 * function instead.
 *
 * Upon return, 'version' is updated to contain the OSPF version number for the
 * packet so that the returned pointer may be cast to the correct type.
 * The version parameter MUST contain a valid pointer; it MUST NOT be NULL.
 *
 * 'remaining' is also set to contain the number of captured bytes remaining
 * starting from the pointer returned by this function. 
 *
 * @note Unlike trace_get_transport(), this function will return NULL if the
 * OSPF header is incomplete or truncated.
 */
DLLEXPORT SIMPLE_FUNCTION
void *trace_get_ospf_header(libtrace_packet_t *packet, uint8_t *version,
                uint32_t *remaining);

/** Get a pointer to the contents of the OSPF packet *after* the OSPF header
 * @param header        The OSPF header to get the OSPF contents from
 * @param[out] ospf_type        The OSPF packet type
 * @param[in, out] remaining    Updated with the number of captured bytes remaining
 * @return A pointer to the first byte after the OSPF header.
 *
 * This function returns a void pointer that can be cast appropriately
 * based on the ospf_type. For example, if the ospf_type is TRACE_OSPF_HELLO 
 * then the return pointer should be cast as a libtrace_ospf_hello_v2_t 
 * structure.
 *
 * If the OSPF header is truncated, then NULL will be returned. If the OSPF 
 * contents are missing or truncated, the pointer to the start of the content 
 * will still be returned so be careful to check the value of remaining.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the OSPF header. It will be updated
 * to contain the number of bytes remaining from the start of the OSPF contents.
 *
 * @note This function only works for OSPF version 2 packets.
 * @note Use trace_get_first_ospf_lsa_v2_from_X() and trace_get_next_ospf_lsa_v2() to read the LSAs from Link State Update packets.
 * @note Use trace_get_first_ospf_lsa_v2_from_X() and trace_get_next_ospf_lsa_header_v2() to read the LSA headers from Link State Ack packets.
 * 
 */ 
DLLEXPORT SIMPLE_FUNCTION
void *trace_get_ospf_contents_v2(libtrace_ospf_v2_t *header,
                uint8_t *ospf_type, uint32_t *remaining);

/** Get a pointer to the start of the first LSA contained within an LS Update packet
 * @param ls_update     Pointer to the LS Update header
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @return A pointer to the first LSA in the packet.
 *
 * This function simply skips past the LS Update header to provide a suitable
 * pointer to pass into trace_get_next_ospf_lsa_v2.
 *
 * If the OSPF packet is truncated, then NULL will be returned.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the LS Update header. It will be 
 * updated to contain the number of bytes remaining from the start of the 
 * first LSA.
 *
 * @note This function only works for OSPF version 2 packets.
 * @note trace_get_next_ospf_lsa_v2() should be subequently used to process the LSAs
 */
DLLEXPORT SIMPLE_FUNCTION 
unsigned char *trace_get_first_ospf_lsa_from_update_v2(
                libtrace_ospf_ls_update_t *ls_update,
                uint32_t *remaining);

/** Get a pointer to the start of the first LSA contained within an Database Description packet
 * @param db_desc       Pointer to the Database Description header
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @return A pointer to the first LSA in the packet.
 *
 * This function simply skips past the Database Description header to provide a 
 * suitable pointer to pass into trace_get_next_ospf_lsa_header_v2.
 *
 * If the OSPF packet is truncated, then NULL will be returned.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the Database Description header. It 
 * will be updated to contain the number of bytes remaining from the start of 
 * the first LSA.
 *
 * @note This function only works for OSPF version 2 packets.
 * @note trace_get_next_ospf_lsa_header_v2() should be subequently used to process the LSA headers
 */
DLLEXPORT SIMPLE_FUNCTION 
unsigned char *trace_get_first_ospf_lsa_from_db_desc_v2(
                libtrace_ospf_db_desc_v2_t *db_desc,
                uint32_t *remaining);

/** Get a pointer to the start of the first link contained within a Router LSA
 * @param lsa   Pointer to the Router LSA
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @return A pointer to the first link in the packet.
 *
 * This function simply skips past the Router LSA header to provide a 
 * suitable pointer to pass into trace_get_next_ospf_link_v2.
 *
 * If the OSPF packet is truncated, then NULL will be returned.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the Router LSA (not including the LSA 
 * header) header. It will be updated to contain the number of bytes remaining 
 * from the start of the first Link.
 *
 * @note This function only works for OSPF version 2 packets.
 * @note trace_get_next_ospf_link_v2() should be subequently used to process
 * the links
 */
DLLEXPORT SIMPLE_FUNCTION
unsigned char *trace_get_first_ospf_link_from_router_lsa_v2(
                libtrace_ospf_router_lsa_v2_t *lsa,
                uint32_t *remaining);

/** Parses an OSPF Router LSA Link and finds the next Link (if there is one)
 * @param[in,out] current       Pointer to the next Link (updated by this function)
 * @param[out] link             Set to point to the Link located at the original value of current
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @param[out] link_len         Set to the size of the Link pointed to by 'link'
 * @return 0 if there are no more links after the current one, 1 otherwise.
 *
 * When called, 'current' MUST point to an OSPF Router LSA link. Ideally, this
 * would come from either a call to 
 * trace_get_first_ospf_link_from_router_lsa_v2() or a previous call of this
 * function. 
 *
 * 'link' will be set to the value of 'current', so that the caller may then
 * do any processing they wish on that particular link. 'current' is advanced
 * to point to the next link and 'link_len' is updated to report the size of
 * the original link.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the Link pointed to by 'current'.
 * It will be updated to contain the number of bytes remaining from the start 
 * of the next link.
 *
 * If this function returns 0 but 'link' is NOT NULL, that link is still valid
 * but there are no more links after this one.
 * If this function returns 0 AND link is NULL, the link is obviously not 
 * suitable for processing. 
 *
 * @note This function only works for OSPF version 2 packets.
 */
DLLEXPORT SIMPLE_FUNCTION
int trace_get_next_ospf_link_v2(unsigned char **current,
                libtrace_ospf_link_v2_t **link,
                uint32_t *remaining,
                uint32_t *link_len);

/** Parses an OSPF LSA and finds the next LSA (if there is one)
 * @param[in,out] current       Pointer to the next LSA (updated by this function)
 * @param[out] lsa_hdr          Set to point to the header of the LSA located at the original value of current
 * @param[out] lsa_body         Set to point to the body of the LSA located at the original value of current
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @param[out] lsa_type         Set to the type of the LSA located at the original value of current
 * @param[out] lsa_length       Set to the size of the LSA located at the original value of current
 * @return 1 if there are more LSAs after the current one, 0 if there are no more LSAs to come, and -1 if the current LSA is incomplete, truncated or invalid.
 *
 * When called, 'current' MUST point to an OSPF LSA. Ideally, this would come 
 * from either a call to trace_get_first_ospf_lsa_from_update_v2() or a 
 * previous call of this function. 
 *
 * This function should only be used to access COMPLETE LSAs, i.e. LSAs that
 * have both a header and a body. In OSPFv2, only the LSAs contained within
 * LSA Update packets meet this requirement. trace_get_next_ospf_lsa_header_v2
 * should be used to read header-only LSAs, e.g. those present in LS Acks.
 *
 * 'lsa_hdr' will be set to the value of 'current', so that the caller may then
 * do any processing they wish on that particular LSA. 'lsa_body' will be set
 * to point to the first byte after the LSA header. 'current' is advanced
 * to point to the next LSA. 'lsa_length' is updated to contain the size of
 * the parsed LSA, while 'lsa_type' is set to indicate the LSA type.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the LSA pointed to by 'current'.
 * It will be updated to contain the number of bytes remaining from the start 
 * of the next LSA.
 *
 * If this function returns 0 but 'lsa_hdr' is NOT NULL, that LSA is still 
 * valid but there are no more LSAs after this one.
 * If this function returns 0 AND 'lsa_hdr' is NULL, the LSA is obviously not 
 * suitable for processing. 
 *
 * It is also recommended to check the value of 'lsa_body' before 
 * de-referencing it. 'lsa_body' will be set to NULL if there is only an LSA
 * header present.
 * 
 * @note This function only works for OSPF version 2 packets.
 *
 */
DLLEXPORT SIMPLE_FUNCTION
int trace_get_next_ospf_lsa_v2(unsigned char **current,
                libtrace_ospf_lsa_v2_t **lsa_hdr,
                unsigned char **lsa_body,
                uint32_t *remaining,
                uint8_t *lsa_type,
                uint16_t *lsa_length);

/** Parses an OSPF LSA header and finds the next LSA (if there is one)
 * @param[in,out] current       Pointer to the next LSA (updated by this function)
 * @param[out] lsa_hdr          Set to point to the header of the LSA located at the original value of current
 * @param[in,out] remaining     Updated with the number of captured bytes remaining
 * @param[out] lsa_length       Set to the size of the LSA located at the original value of current
 * @return 1 if there are more LSAs after the current one, 0 if there are no more LSAs to come, and -1 if the current LSA is incomplete, truncated or invalid.
 *
 * When called, 'current' MUST point to an OSPF LSA. Ideally, this would come 
 * from either a call to trace_get_first_ospf_lsa_from_db_desc_v2() or a 
 * previous call of this function. 
 *
 * This function should only be used to access LSA headers, i.e. LSAs that
 * have a header only. In OSPFv2, the LSAs contained within LSA Ack and 
 * Database Description packets meet this requirement. 
 * trace_get_next_ospf_lsa_v2 should be used to read full LSAs, e.g. those 
 * present in LS Updates.
 *
 * 'lsa_hdr' will be set to the value of 'current', so that the caller may then
 * do any processing they wish on that particular LSA header. 'current' is 
 * advanced to point to the next LSA header. 'lsa_length' is updated to contain 
 * the size of the parsed LSA header.
 *
 * 'remaining' MUST be set to the amount of bytes remaining in the captured
 * packet starting from the beginning of the LSA pointed to by 'current'.
 * It will be updated to contain the number of bytes remaining from the start 
 * of the next LSA.
 *
 * If this function returns 0 but 'lsa_hdr' is NOT NULL, that LSA is still 
 * valid but there are no more LSAs after this one.
 * If this function returns 0 AND 'lsa_hdr' is NULL, the LSA is obviously not 
 * suitable for processing. 
 *
 * @note This function only works for OSPF version 2 packets.
 *
 */
DLLEXPORT SIMPLE_FUNCTION
int trace_get_next_ospf_lsa_header_v2(unsigned char **current,
                libtrace_ospf_lsa_v2_t **lsa_hdr,
                uint32_t *remaining,
                uint8_t *lsa_type,
                uint16_t *lsa_length); 

/** Extracts the metric field from an AS External LSA packet
 *
 * @param as_lsa        The AS External LSA
 * @returns The value of the metric field
 *
 * The metric field in the AS External LSA packet is a 24-bit value, which
 * is difficult to extract correctly. To avoid byte-ordering issues, use this
 * function which will extract the correct value for you.
 */
DLLEXPORT SIMPLE_FUNCTION
uint32_t trace_get_ospf_metric_from_as_external_lsa_v2(
                libtrace_ospf_as_external_lsa_v2_t *as_lsa);

/** Extracts the metric field from a Summary LSA packet
 *
 * @param sum_lsa       The Summary LSA
 * @returns The value of the metric field
 *
 * The metric field in the Summary LSA packet is a 24-bit value, which
 * is difficult to extract correctly. To avoid byte-ordering issues, use this
 * function which will extract the correct value for you.
 */
DLLEXPORT SIMPLE_FUNCTION
uint32_t trace_get_ospf_metric_from_summary_lsa_v2(
                libtrace_ospf_summary_lsa_v2_t *sum_lsa);


/** Gets the destination MAC address for a given packet
 * @param packet        The packet to extract the destination MAC address from
 *
 * @return A pointer to the destination MAC address field in the layer 2 
 * header, (or NULL if there is no destination MAC address or layer 2 header
 * available)
 *
 * @note This is a zero-copy function, so the memory that the returned pointer
 * points to is part of the packet itself. 
 */
DLLEXPORT SIMPLE_FUNCTION
uint8_t *trace_get_destination_mac(libtrace_packet_t *packet);

/** Gets the source MAC address for a given packet
 * @param packet        The packet to extract the source MAC address from
 *
 * @return A pointer to the source MAC address field in the layer 2 
 * header, (or NULL if there is no source MAC address or layer 2 header
 * available)
 *
 * @note This is a zero-copy function, so the memory that the returned pointer
 * points to is part of the packet itself. 
 */
DLLEXPORT SIMPLE_FUNCTION
uint8_t *trace_get_source_mac(libtrace_packet_t *packet);

/** Get the source IP address for a given packet
 * @param packet        The packet to extract the source IP address from
 * @param addr          A pointer to a sockaddr structure to store the address 
 *                      in. If NULL, static storage is used instead.
 * @return A pointer to a sockaddr holding a v4 or v6 IP address or on some 
 * platforms a sockaddr holding a MAC address. Returns NULL if no source IP
 * address was available.
 *
 * @note The best way to use this function is to pass in a pointer to the
 * struct sockaddr_storage for the addr parameter. This will avoid problems
 * with trying to shoe-horn an IPv6 address into a sockaddr that only supports
 * IPv4.
 */
DLLEXPORT SIMPLE_FUNCTION
struct sockaddr *trace_get_source_address(const libtrace_packet_t *packet,
                struct sockaddr *addr);

/** Get the source IP address for a packet and convert it into a string
 * @param packet        The packet to extract the source IP address from
 * @param space         A pointer to a character buffer to store the address 
 *                      in. If NULL, static storage is used instead.
 * @param spacelen      The size of the buffer passed in via 'space'. Set this
 *                      to zero if you are going to pass in a NULL buffer.
 * @return A pointer to a character buffer containing the string representation
 * of the source IP address. For packets where there is no suitable IP address,
 * the source MAC will be returned instead. Returns NULL if no valid address
 * is available.
 *
 * @note Be wary of the possibility of the address being an IPv6 address - make
 * sure your buffer is large enough!
 *
 * New in libtrace 3.0.17.
 */
DLLEXPORT SIMPLE_FUNCTION
char *trace_get_source_address_string(const libtrace_packet_t *packet,
                char *space, int spacelen);

/** Get the destination IP address for a given packet
 * @param packet        The packet to extract the destination IP address from
 * @param addr          A pointer to a sockaddr structure to store the address 
 *                      in. If NULL, static storage is used instead.
 * @return A pointer to a sockaddr holding a v4 or v6 IP address or on some 
 * platforms a sockaddr holding a MAC address. Returns NULL if no destination 
 * IP address was available.
 *
 * @note The best way to use this function is to pass in a pointer to the
 * struct sockaddr_storage for the addr parameter. This will avoid problems
 * with trying to shoe-horn an IPv6 address into a sockaddr that only supports
 * IPv4.
 */
DLLEXPORT SIMPLE_FUNCTION
struct sockaddr *trace_get_destination_address(const libtrace_packet_t *packet,
                struct sockaddr *addr);

/** Get the destination IP address for a packet and convert it into a string
 * @param packet        The packet to extract the destination IP address from
 * @param space         A pointer to a character buffer to store the address 
 *                      in. If NULL, static storage is used instead.
 * @param spacelen      The size of the buffer passed in via 'space'. Set this
 *                      to zero if you are going to pass in a NULL buffer.
 * @return A pointer to a character buffer containing the string representation
 * of the destination IP address. For packets where there is no suitable IP 
 * address, the destination MAC will be returned instead. Returns NULL if no 
 * valid address is available.
 *
 * @note Be wary of the possibility of the address being an IPv6 address - make
 * sure your buffer is large enough!
 *
 * New in libtrace 3.0.17.
 */
DLLEXPORT SIMPLE_FUNCTION
char *trace_get_destination_address_string(const libtrace_packet_t *packet,
                char *space, int spacelen);

/** Parses an IP or TCP option
 * @param[in,out] ptr   The pointer to the current option
 * @param[in,out] len   The total length of all the remaining options
 * @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.
 */
DLLEXPORT 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 the timestamp describing when a packet was 
 * captured and can convert it into various formats
 * @{
 */

/** Get the packet timestamp in the DAG time format 
 * @param packet        The packet to extract the timestamp from
 *
 * @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)
 */
DLLEXPORT SIMPLE_FUNCTION
uint64_t trace_get_erf_timestamp(const libtrace_packet_t *packet);

/** Get the packet timestamp as a struct timeval
 * @param packet        The packet to extract the timestamp from
 *
 * @return The time that this packet was captured in a struct timeval
 */ 
DLLEXPORT SIMPLE_FUNCTION
struct timeval trace_get_timeval(const libtrace_packet_t *packet);

/** Get the packet timestamp as a struct timespec
 * @param packet        The packet to extract the timestamp from
 *
 * @return The time that this packet was captured in a struct timespec
 */ 
DLLEXPORT SIMPLE_FUNCTION
struct timespec trace_get_timespec(const libtrace_packet_t *packet);

/** Get the packet timestamp in floating point seconds
 * @param packet        The packet to extract the timestamp from
 *
 * @return time that this packet was seen in 64-bit floating point seconds from
 * the UNIX epoch (1970-01-01 00:00:00 UTC).
 */
DLLEXPORT SIMPLE_FUNCTION
double trace_get_seconds(const libtrace_packet_t *packet);

/** Seek within an input trace to a time specified in floating point seconds
 * @param trace         The input trace to seek within
 * @param seconds       The time to seek to, in floating point seconds
 * @return 0 on success, -1 if the seek fails. Use trace_perror() to determine
 * the error that occurred.
 *
 * This will make the next packet read to be the first packet to occur at or 
 * after the specified time.  This must be called in the configuration state 
 * (i.e. before trace_start() or after trace_pause()).
 *
 * The time format accepted by this function is 64-bit floating point seconds
 * since the UNIX epoch (1970-01-01 00:00:00 UTC), i.e. the same format as
 * trace_get_seconds().
 *
 * @note This function may be extremely slow.
 */
DLLEXPORT int trace_seek_seconds(libtrace_t *trace, double seconds);

/** Seek within an input trace to a time specified as a timeval
 * @param trace         The input trace to seek within
 * @param tv            The time to seek to, as a timeval
 *
 * @return 0 on success, -1 if the seek fails. Use trace_perror() to determine
 * the error that occurred.
 *
 * This will make the next packet read to be the first packet to occur at or 
 * after the specified time.  This must be called in the configuration state 
 * (i.e. before trace_start() or after trace_pause()).
 *
 * @note This function may be extremely slow.
 */
DLLEXPORT int trace_seek_timeval(libtrace_t *trace, struct timeval tv);

/** Seek within an input trace to a time specified as an ERF timestamp
 * @param trace         The input trace to seek within
 * @param ts            The time to seek to, as an ERF timestamp
 *
 * @return 0 on success, -1 if the seek fails. Use trace_perror() to determine
 * the error that occurred.
 *
 * This will make the next packet read to be the first packet to occur at or 
 * after the specified time.  This must be called in the configuration state 
 * (i.e. before trace_start() or after trace_pause()).
 *
 * The time format accepted by this function is the ERF timestamp, which is a
 * 64-bit value where the upper 32 bits are seconds since the UNIX epoch and
 * the lower 32 bits are partial seconds.
 *
 * @note This function may be extremely slow.
 */
DLLEXPORT int trace_seek_erf_timestamp(libtrace_t *trace, uint64_t ts);

/*@}*/

/** @name Sizes
 * This section deals with finding or setting the various different lengths
 * that a packet can have, e.g. capture lengths, wire lengths, etc.
 * @{
 */
/** Get the current size of the packet (in bytes), taking into account any 
 * truncation or snapping that may have previously been performed. 
 *
 * @param packet        The packet to determine the capture length for
 * @return The size of the packet read from the input trace, i.e. what is
 * actually available to libtrace at the moment.
 *
 * @note Most traces are header captures, so this value may not be the same
 * as the size of the packet when it was captured. Use trace_get_wire_length()
 * to get 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 framing headers. For example, an Ethernet 
 * packet with an empty TCP packet will return sizeof(ethernet_header) + 
 * sizeof(ip_header) + sizeof(tcp_header), but not the capture format
 * (pcap/erf/etc) header.
 */
DLLEXPORT SIMPLE_FUNCTION
size_t trace_get_capture_length(const libtrace_packet_t *packet);

/** Get the size of the packet as it was originally seen on the wire (in bytes).
 * @param packet        The packet to determine the wire length for
 * @return The size of the packet as it was on the wire.
 *
 * @note This value may not be the same as the capture length, due to 
 * truncation.
 *
 * @note trace_get_wire_length \em includes  the Frame Check Sequence. This is 
 * different behaviour compared to most PCAP-based tools.
 *
 * @note The return size refers to the network-level payload of the packet and
 * does not include any capture framing headers. For example, an Ethernet 
 * packet with an empty TCP packet will return sizeof(ethernet_header) + 
 * sizeof(ip_header) + sizeof(tcp_header), but not the capture format
 * (pcap/erf/etc) header.
 */ 
DLLEXPORT SIMPLE_FUNCTION
size_t trace_get_wire_length(const libtrace_packet_t *packet);

/** Get the length of the capture framing headers (in bytes).
 * @param packet        The packet to determine the framing length for
 * @return The size of the capture format header encapsulating the packet.
 *
 * @note This length corresponds to the difference between the amount of
 * memory required to store a captured packet and the capture length reported
 * by trace_capture_length()
 */ 
DLLEXPORT SIMPLE_FUNCTION
size_t trace_get_framing_length(const libtrace_packet_t *packet);

/** Get the length of the original payload content of the packet (in bytes).
 * @param packet        The packet to determine the payload length for
 * @return The size of the packet payload (without headers). Returns 0 if
 * unable to calculate payload length correctly.
 *
 * This function reports the amount of data that followed the transport header
 * when the packet was originally captured, i.e. prior to any snapping. Best
 * described as the wire length minus the packet headers. 
 *
 * Currently only supports some protocols and will return 0 if an unsupported
 * protocol header is encountered, or if one of the headers is truncated. 
 *
 * @note Supports IPv4, IPv6, TCP, UDP and ICMP.
 */ 
DLLEXPORT SIMPLE_FUNCTION
size_t trace_get_payload_length(const libtrace_packet_t *packet);

/** Truncate ("snap") the packet to the suggested length
 * @param packet        The packet to truncate
 * @param size          The new length of the packet (in bytes)
 *
 * @return The new capture length of the packet or the original capture
 * length of the packet if unchanged.
 *
 * This function will modify the capture length of the given packet. The wire
 * length will not be changed, so you can always determine what the original
 * packet size was, prior to the truncation.
 *
 * @note You can only use this function to decrease the capture length. Any
 * attempt to increase capture length will have no effect.
 */
DLLEXPORT size_t trace_set_capture_length(libtrace_packet_t *packet, size_t size);

/*@}*/


/** Gets the link layer type for a packet
 * @param packet        The packet to extract the link layer type for
 * @return A libtrace_linktype_t describing the link layer protocol being used
 * by this packet.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_linktype_t trace_get_link_type(const libtrace_packet_t *packet);

/** Set the direction flag for a packet, if the capture format supports
 * direction tagging.
 *
 * @param packet        The packet to set the direction for
 * @param direction     The new direction 
 * @returns -1 on error, or the direction that was set.
 *
 * @note Few capture formats actually support direction tagging. Most notably,
 * we cannot set the direction on PCAP packets.
 */
DLLEXPORT libtrace_direction_t trace_set_direction(libtrace_packet_t *packet, libtrace_direction_t direction);

/** Get the direction flag for a packet, if it has one.
 * @param packet  The packet to get the direction for
 *
 * @return A value representing the direction flag, or -1 if this is not 
 * supported by the capture format.
 * 
 * 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 certain 
 * traces, e.g. in the Waikato traces, 2 is used to represent an "Unknown"
 * direction.
 *
 * For DAG/ERF traces, the direction is extracted from the "Interface" bits in 
 * the ERF header, which can range from 0 - 3.
 */
DLLEXPORT SIMPLE_FUNCTION
libtrace_direction_t trace_get_direction(const libtrace_packet_t *packet);

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

/** Create 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  
 * @return              An opaque pointer to a libtrace_filter_t object
 * @note                The supplied byte-code is not checked for correctness.
 *                      Instead, incorrect byte-code will generate an error
 *                      once the filter is actually used.
 * @author              Scott Raynel
 */
DLLEXPORT libtrace_filter_t *
trace_create_filter_from_bytecode(void *bf_insns, unsigned int bf_len);

/** Apply a BPF filter to a packet
 * @param filter        The filter to be applied        
 * @param packet        The packet to be matched against the filter
 * @return >0 if the filter matches, 0 if it doesn't, -1 on error.
 * 
 * @note Due to the way BPF filters are built, the filter is not actually
 * compiled until the first time trace_create_filter is called. If your filter
 * is incorrect, it will generate an error message and assert, exiting the
 * program. This behaviour may change to a more graceful handling of this error
 * in the future.
 */
DLLEXPORT int trace_apply_filter(libtrace_filter_t *filter,
                const libtrace_packet_t *packet);

/** Destroy a BPF filter
 * @param filter        The filter to be destroyed
 * 
 * Deallocates all the resources associated with a BPF filter.
 */
DLLEXPORT void trace_destroy_filter(libtrace_filter_t *filter);
/*@}*/

/** @name Portability
 * This section contains functions that deal with portability issues, e.g. byte
 * ordering.
 * @{
 */

/** Converts an ethernet address to a printable string 
 * @param addr  Ethernet address in network byte order
 * @param buf   Buffer to store the ascii representation, or NULL to indicate
 * that static storage should be used.
 * @return buf, or if buf is NULL then a statically allocated buffer.
 *
 * This function is similar to the GNU ether_ntoa_r function, with a few
 * minor differences.  If NULL is passed as buf, then the function will
 * use an internal static buffer. If NULL isn't passed then the function
 * will use that buffer instead.
 *
 * The address pointers returned by trace_get_source_mac() and 
 * trace_get_destination_mac() can be passed directly into this function.
 *
 * @note The type of addr isn't struct ether_addr as it is with ether_ntoa_r,
 * however it is bit compatible so that a cast will work.
 */ 
DLLEXPORT char *trace_ether_ntoa(const uint8_t *addr, char *buf);

/** Convert a string to an ethernet address
 * @param buf   A string containing an Ethernet address in hex format 
 * delimited with :'s.
 * @param addr  Buffer to store the binary representation, or NULL to indicate
 * that static storage should be used.
 * @return addr, or if addr is NULL then a statically allocated buffer.
 *
 * This function is similar to the GNU ether_aton_r function, with a few
 * minor differences.  If NULL is passed as addr, then the function will
 * use an internal static buffer. If NULL isn't passed then the function will 
 * use that buffer instead.
 * 
 * The address returned by this function will be in network byte order.
 *
 * @note the type of addr isn't struct ether_addr as it is with ether_aton_r,
 * however it is bit compatible so that a cast will work.
 */
DLLEXPORT uint8_t *trace_ether_aton(const char *buf, uint8_t *addr);

/*@}*/

/** @name Ports
 * This section contains functions for dealing with port numbers at the 
 * transport layer.
 *
 * @{
 */

/** An indication of which port is the "server" port for a given port pair */
typedef enum {
        USE_DEST,       /**< Destination port is the server port */
        USE_SOURCE      /**< Source port is the server port */
} serverport_t;

/** Gets the source port for a given packet
 * @param packet        The packet to get the source port from
 * @return The source port in HOST byte order or 0 if no suitable port number
 * can be extracted from the packet.
 *
 * This function will return 0 if the transport protocol is known not to
 * use port numbers, e.g. ICMP. 0 is also returned if no transport header is
 * present in the packet or the transport header has been truncated such that
 * the port fields are not readable.
 *
 * @note If the transport protocol is not known by libtrace, the first two
 * bytes of the transport header will be treated as the source port field.
 */
DLLEXPORT SIMPLE_FUNCTION
uint16_t trace_get_source_port(const libtrace_packet_t *packet);

/** Gets the destination port for a given packet
 * @param packet        The packet to get the destination port from
 * @return The destination port in HOST byte order or 0 if no suitable port
 * number can be extracted from the packet.
 *
 * This function will return 0 if the transport protocol is known not to
 * use port numbers, e.g. ICMP. 0 is also returned if no transport header is
 * present in the packet or the transport header has been truncated such that
 * the port fields are not readable.
 *
 * @note If the transport protocol is not known by libtrace, the third and
 * fourth bytes of the transport header will be treated as the destination 
 * port field.
 *
 */
DLLEXPORT SIMPLE_FUNCTION
uint16_t trace_get_destination_port(const libtrace_packet_t *packet);

/** Hint at which of the two provided ports is the server port.
 *
 * @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 describing on which of the two ports
 * is most likely to be the server port.
 *
 * @note Ports must be provided in HOST byte order!
 *
 * This function is based almost entirely on heuristics and should not be
 * treated as a definitive means of identifying the server port. However, it
 * is deterministic, so it is very handy for identifying both halves of the
 * same flow. 
 */
DLLEXPORT SIMPLE_FUNCTION
int8_t trace_get_server_port(uint8_t protocol, uint16_t source, uint16_t dest);

/*@}*/

/** @name Wireless trace support
 * Functions to access wireless information from packets that have wireless
 * monitoring headers such as Radiotap or Prism.
 * 
 * The trace_get_wireless_* functions provide an abstract interface for
 * retrieving information from wireless traces. They take a pointer to the
 * wireless monitoring header (usually found with trace_get_packet_meta()) and
 * the linktype of the header passed in.
 * 
 * All of the trace_get_wireless_* functions return false if the requested
 * information was unavailable, or true if it was. The actual data is stored
 * in an output variable supplied by the caller. Values returned into the 
 * output variable will always be returned in host byte order.
 * @{
 */


#ifndef ARPHRD_80211_RADIOTAP
/** libc doesn't define this yet, so we have to do so ourselves */
#define ARPHRD_80211_RADIOTAP 803
#endif

/** Get the wireless Timer Synchronisation Function
 *
 * Gets the value of the timer synchronisation function for this frame, which
 * is a value in microseconds indicating the time that the first bit of the
 * MPDU was received by the MAC.
 *
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in 
 * @param[out] tsft The value of the timer synchronisation function. 
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_tsft(void *linkptr,
        libtrace_linktype_t linktype, uint64_t *tsft);

/** Get the wireless data rate 
 *
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] rate The data-rate of the frame in units of 500kbps
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_rate(void *linkptr,
        libtrace_linktype_t linktype, uint8_t *rate);

/** Get the wireless channel frequency
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] freq The frequency in MHz of the channel the frame was 
 * transmitted or received on.
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_freq(void *linkptr,
        libtrace_linktype_t linktype, uint16_t *freq);

/** Get the wireless signal strength in dBm 
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] strength The RF signal power at the antenna, in dB difference
 * from 1mW.
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_signal_strength_dbm(void *linkptr,
        libtrace_linktype_t linktype, int8_t *strength);

/** Get the wireless noise strength in dBm
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] strength The RF noise power at the antenna, in dB difference 
 * from 1mW. 
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_noise_strength_dbm(void *linkptr,
        libtrace_linktype_t linktype, int8_t *strength);

/** Get the wireless signal strength in dB
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] strength The RF signal power at the antenna, in dB difference 
 * from a fixed reference. 
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_signal_strength_db(void *linkptr,
        libtrace_linktype_t linktype, uint8_t *strength);

/** Get the wireless noise strength in dB 
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] strength The RF noise power at the antenna, in dB difference 
 * from a fixed reference. 
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_noise_strength_db(void *linkptr,
        libtrace_linktype_t linktype, uint8_t *strength);

/** Get the wireless transmit attenuation 
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] attenuation The transmit power as a unitless distance from 
 * maximum power set at factory calibration. 0 indicates maximum transmission 
 * power.
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_tx_attenuation(void *linkptr,
        libtrace_linktype_t linktype, uint16_t *attenuation);

/** Get the wireless transmit attenuation in dB
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] attenuation The transmit power as dB difference from maximum 
 * power set at factory calibration. 0 indicates maximum power.
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_tx_attenuation_db(void *linkptr,
        libtrace_linktype_t linktype, uint16_t *attenuation);

/** Get the wireless transmit power in dBm 
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in 
 * @param[out] txpower The transmit power as dB from a 1mW reference. This is 
 * the absolute power level measured at the antenna port.  
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_tx_power_dbm(void *linkptr, 
                libtrace_linktype_t linktype, int8_t *txpower);

/** Get the wireless antenna 
 * @param linkptr The wireless meta header
 * @param linktype The linktype of the wireless meta header passed in
 * @param[out] antenna The antenna that was used to transmit or receive the 
 * frame.
 * @return true if the field was available, false if not.
 */
DLLEXPORT bool trace_get_wireless_antenna(void *linkptr,
        libtrace_linktype_t linktype, uint8_t *antenna);

/*@}*/

#ifdef __cplusplus
} /* extern "C" */
#endif /* #ifdef __cplusplus */
#endif /* LIBTRACE_H_ */