/*
 * Copyright (c) 2008-2017 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
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 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
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 */
/*!
 *       @header kpi_mbuf.h
 *       This header defines an API for interacting with mbufs. mbufs are the
 *       primary method of storing packets in the networking stack.
 *
 *       mbufs are used to store various items in the networking stack. The
 *       most common usage of an mbuf is to store a packet or data on a
 *       socket waiting to be sent or received. The mbuf is a contiguous
 *       structure with some header followed by some data. To store more data
 *       than would fit in an mbuf, external data is used. Most mbufs with
 *       external data use clusters to store the external data.
 *
 *       mbufs can be chained, contiguous data in a packet can be found by
 *       following the m_next chain. Packets may be bundled together using
 *       m_nextpacket. Many parts of the stack do not properly handle chains
 *       of packets. When in doubt, don't chain packets.
 */

#ifndef __KPI_MBUF__
#define __KPI_MBUF__
#include <sys/kernel_types.h>
#include <mach/vm_types.h>
#ifdef KERNEL_PRIVATE
#include <mach/kern_return.h>
#endif /* KERNEL_PRIVATE */

/*!
 *       @enum mbuf_flags_t
 *       @abstract Constants defining mbuf flags. Only the flags listed below
 *               can be set or retrieved.
 *       @constant MBUF_EXT Indicates this mbuf has external data.
 *       @constant MBUF_PKTHDR Indicates this mbuf has a packet header.
 *       @constant MBUF_EOR Indicates this mbuf is the end of a record.
 *       @constant MBUF_LOOP Indicates this packet is looped back.
 *       @constant MBUF_BCAST Indicates this packet will be sent or was
 *               received as a brodcast.
 *       @constant MBUF_MCAST Indicates this packet will be sent or was
 *               received as a multicast.
 *       @constant MBUF_FRAG Indicates this packet is a fragment of a larger
 *               packet.
 *       @constant MBUF_FIRSTFRAG Indicates this packet is the first fragment.
 *       @constant MBUF_LASTFRAG Indicates this packet is the last fragment.
 *       @constant MBUF_PROMISC Indicates this packet was only received
 *               because the interface is in promiscuous mode. This should be set
 *               by the demux function. These packets will be discarded after
 *               being passed to any interface filters.
 */
enum {
	MBUF_EXT        = 0x0001,       /* has associated external storage */
	MBUF_PKTHDR     = 0x0002,       /* start of record */
	MBUF_EOR        = 0x0004,       /* end of record */
	MBUF_LOOP       = 0x0040,       /* packet is looped back */

	MBUF_BCAST      = 0x0100,       /* send/received as link-level broadcast */
	MBUF_MCAST      = 0x0200,       /* send/received as link-level multicast */
	MBUF_FRAG       = 0x0400,       /* packet is a fragment of a larger packet */
	MBUF_FIRSTFRAG  = 0x0800,       /* packet is first fragment */
	MBUF_LASTFRAG   = 0x1000,       /* packet is last fragment */
	MBUF_PROMISC    = 0x2000,       /* packet is promiscuous */
	MBUF_HASFCS     = 0x4000        /* packet has FCS */
};
typedef u_int32_t mbuf_flags_t;

/*!
 *       @enum mbuf_type_t
 *       @abstract Types of mbufs.
 *       @discussion Some mbufs represent packets, some represnt data waiting
 *               on sockets. Other mbufs store control data or other various
 *               structures. The mbuf type is used to store what sort of data the
 *               mbuf contains.
 *       @constant MBUF_MT_FREE Indicates the mbuf is free and is
 *               sitting on the queue of free mbufs. If you find that an mbuf you
 *               have a reference to has this type, something has gone terribly
 *               wrong.
 *       @constant MBUF_MT_DATA Indicates this mbuf is being used to store
 *               data.
 *       @constant MBUF_MT_HEADER Indicates this mbuf has a packet header,
 *               this is probably a packet.
 *       @constant MBUF_MT_SOCKET Socket structure.
 *       @constant MBUF_MT_PCB Protocol control block.
 *       @constant MBUF_MT_RTABLE Routing table entry.
 *       @constant MBUF_MT_HTABLE IMP host tables???.
 *       @constant MBUF_MT_ATABLE Address resolution table data.
 *       @constant MBUF_MT_SONAME Socket name, usually a sockaddr of some
 *               sort.
 *       @constant MBUF_MT_FTABLE Fragment reassembly header.
 *       @constant MBUF_MT_RIGHTS Access rights.
 *       @constant MBUF_MT_IFADDR Interface address.
 *       @constant MBUF_MT_CONTROL Extra-data protocol message (control
 *               message).
 *       @constant MBUF_MT_OOBDATA Out of band data.
 */
enum {
	MBUF_TYPE_FREE          = 0,    /* should be on free list */
	MBUF_TYPE_DATA          = 1,    /* dynamic (data) allocation */
	MBUF_TYPE_HEADER        = 2,    /* packet header */
	MBUF_TYPE_SOCKET        = 3,    /* socket structure */
	MBUF_TYPE_PCB           = 4,    /* protocol control block */
	MBUF_TYPE_RTABLE        = 5,    /* routing tables */
	MBUF_TYPE_HTABLE        = 6,    /* IMP host tables */
	MBUF_TYPE_ATABLE        = 7,    /* address resolution tables */
	MBUF_TYPE_SONAME        = 8,    /* socket name */
	MBUF_TYPE_SOOPTS        = 10,   /* socket options */
	MBUF_TYPE_FTABLE        = 11,   /* fragment reassembly header */
	MBUF_TYPE_RIGHTS        = 12,   /* access rights */
	MBUF_TYPE_IFADDR        = 13,   /* interface address */
	MBUF_TYPE_CONTROL       = 14,   /* extra-data protocol message */
	MBUF_TYPE_OOBDATA       = 15    /* expedited data  */
};
typedef u_int32_t mbuf_type_t;

/*!
 *       @enum mbuf_csum_request_flags_t
 *       @abstract Checksum performed/requested flags.
 *       @discussion Mbufs often contain packets. Some hardware supports
 *               performing checksums in hardware. The stack uses these flags to
 *               indicate to the driver what sort of checksumming should be
 *               handled in by the driver/hardware. These flags will only be set
 *               if the driver indicates that it supports the corresponding
 *               checksums using ifnet_set_offload.
 *       @constant MBUF_CSUM_REQ_IP Indicates the IP checksum has not been
 *               calculated yet.
 *       @constant MBUF_CSUM_REQ_TCP Indicates the TCP checksum has not been
 *               calculated yet.
 *       @constant MBUF_CSUM_REQ_UDP Indicates the UDP checksum has not been
 *               calculated yet.
 *       @constant MBUF_CSUM_REQ_TCPIPV6 Indicates the TCP checksum for IPv6
 *               has not been calculated yet.
 *       @constant MBUF_CSUM_REQ_UDPIPV6 Indicates the UDP checksum for IPv6
 *               has not been calculated yet.
 */
enum {
	MBUF_TSO_IPV4           = 0x100000,
	MBUF_TSO_IPV6           = 0x200000
};
typedef u_int32_t mbuf_tso_request_flags_t;

enum {
#ifdef KERNEL_PRIVATE
	MBUF_CSUM_PARTIAL       = 0x1000,       /* 16-bit 1's complement sum */
	MBUF_CSUM_REQ_SUM16     = MBUF_CSUM_PARTIAL,
	MBUF_CSUM_REQ_ZERO_INVERT = 0x2000,
#endif /* KERNEL_PRIVATE */
	MBUF_CSUM_REQ_IP        = 0x0001,
	MBUF_CSUM_REQ_TCP       = 0x0002,
	MBUF_CSUM_REQ_UDP       = 0x0004,
	MBUF_CSUM_REQ_TCPIPV6   = 0x0020,
	MBUF_CSUM_REQ_UDPIPV6   = 0x0040
};
typedef u_int32_t mbuf_csum_request_flags_t;

/*!
 *       @enum mbuf_csum_performed_flags_t
 *       @abstract Checksum performed/requested flags.
 *       @discussion Mbufs often contain packets. Some hardware supports
 *               performing checksums in hardware. The driver uses these flags to
 *               communicate to the stack the checksums that were calculated in
 *               hardware.
 *       @constant MBUF_CSUM_DID_IP Indicates that the driver/hardware verified
 *               the IP checksum in hardware.
 *       @constant MBUF_CSUM_IP_GOOD Indicates whether or not the IP checksum
 *               was good or bad. Only valid when MBUF_CSUM_DID_IP is set.
 *       @constant MBUF_CSUM_DID_DATA Indicates that the TCP or UDP checksum
 *               was calculated. The value for the checksum calculated in
 *               hardware should be passed as the second parameter of
 *               mbuf_set_csum_performed. The hardware calculated checksum value
 *               can be retrieved using the second parameter passed to
 *               mbuf_get_csum_performed. This should be done for IPv4 or IPv6.
 *       @constant MBUF_CSUM_PSEUDO_HDR If set, this indicates that the
 *               checksum value for MBUF_CSUM_DID_DATA includes the pseudo header
 *               value. If this is not set, the stack will calculate the pseudo
 *               header value and add that to the checksum. The value of this bit
 *               is only valid when MBUF_CSUM_DID_DATA is set.
 */
enum {
#ifdef KERNEL_PRIVATE
	MBUF_CSUM_TCP_SUM16     = MBUF_CSUM_PARTIAL,
#endif /* KERNEL_PRIVATE */
	MBUF_CSUM_DID_IP        = 0x0100,
	MBUF_CSUM_IP_GOOD       = 0x0200,
	MBUF_CSUM_DID_DATA      = 0x0400,
	MBUF_CSUM_PSEUDO_HDR    = 0x0800
};
typedef u_int32_t mbuf_csum_performed_flags_t;

/*!
 *       @enum mbuf_how_t
 *       @abstract Method of allocating an mbuf.
 *       @discussion Blocking on the input or output path can impact
 *               performance. There are some cases where making a blocking call
 *               is acceptable. When in doubt, use MBUF_DONTWAIT.
 *       @constant MBUF_WAITOK Allow a call to allocate an mbuf to block.
 *       @constant MBUF_DONTWAIT Don't allow the mbuf allocation call to
 *               block, if blocking is necessary fail and return immediately.
 */
enum {
	MBUF_WAITOK     = 0,    /* Ok to block to get memory */
	MBUF_DONTWAIT   = 1     /* Don't block, fail if blocking would be required */
};
typedef u_int32_t mbuf_how_t;

typedef u_int32_t mbuf_tag_id_t;
typedef u_int16_t mbuf_tag_type_t;

/*!
 *       @struct mbuf_stat
 *       @discussion The mbuf_stat contains mbuf statistics.
 *       @field mbufs Number of mbufs (free or otherwise).
 *       @field clusters Number of clusters (free or otherwise).
 *       @field clfree Number of free clusters.
 *       @field drops Number of times allocation failed.
 *       @field wait Number of times allocation blocked.
 *       @field drain Number of times protocol drain functions were called.
 *       @field mtypes An array of counts of each type of mbuf allocated.
 *       @field mcfail Number of times m_copym failed.
 *       @field mpfail Number of times m_pullup failed.
 *       @field msize Length of an mbuf.
 *       @field mclbytes Length of an mbuf cluster.
 *       @field minclsize Minimum length of data to allocate a cluster.
 *               Anything smaller than this should be placed in chained mbufs.
 *       @field mlen Length of data in an mbuf.
 *       @field mhlen Length of data in an mbuf with a packet header.
 *       @field bigclusters Number of big clusters.
 *       @field bigclfree Number of unused big clusters.
 *       @field bigmclbytes Length of a big mbuf cluster.
 */
struct mbuf_stat {
	u_int32_t       mbufs;          /* mbufs obtained from page pool */
	u_int32_t       clusters;       /* clusters obtained from page pool */
	u_int32_t       clfree;         /* free clusters */
	u_int32_t       drops;          /* times failed to find space */
	u_int32_t       wait;           /* times waited for space */
	u_int32_t       drain;          /* times drained protocols for space */
	u_short         mtypes[256];    /* type specific mbuf allocations */
	u_int32_t       mcfail;         /* times m_copym failed */
	u_int32_t       mpfail;         /* times m_pullup failed */
	u_int32_t       msize;          /* length of an mbuf */
	u_int32_t       mclbytes;       /* length of an mbuf cluster */
	u_int32_t       minclsize;      /* min length of data to allocate a cluster */
	u_int32_t       mlen;           /* length of data in an mbuf */
	u_int32_t       mhlen;          /* length of data in a header mbuf */
	u_int32_t       bigclusters;    /* number of big clusters */
	u_int32_t       bigclfree;      /* number of big clustser free */
	u_int32_t       bigmclbytes;    /* length of data in a big cluster */
};

/* Parameter for m_copym to copy all bytes */
#define MBUF_COPYALL    1000000000

__BEGIN_DECLS
/* Data access */
/*!
 *       @function mbuf_data
 *       @discussion Returns a pointer to the start of data in this mbuf.
 *               There may be additional data on chained mbufs. The data you're
 *               looking for may not be virtually contiguous if it spans more
 *               than one mbuf.  In addition, data that is virtually contiguous
 *               might not be represented by physically contiguous pages; see
 *               further comments in mbuf_data_to_physical.  Use mbuf_len to
 *               determine the length of data available in this mbuf. If a data
 *               structure you want to access stradles two mbufs in a chain,
 *               either use mbuf_pullup to get the data contiguous in one mbuf
 *               or copy the pieces of data from each mbuf in to a contiguous
 *               buffer. Using mbuf_pullup has the advantage of not having to
 *               copy the data. On the other hand, if you don't make sure there
 *               is space in the mbuf, mbuf_pullup may fail and free the mbuf.
 *       @param mbuf The mbuf.
 *       @result A pointer to the data in the mbuf.
 */
extern void *mbuf_data(mbuf_t mbuf);

/*!
 *       @function mbuf_datastart
 *       @discussion Returns the start of the space set aside for storing
 *               data in an mbuf. An mbuf's data may come from a cluster or be
 *               embedded in the mbuf structure itself. The data pointer
 *               retrieved by mbuf_data may not be at the start of the data
 *               (mbuf_leadingspace will be non-zero). This function will return
 *               a pointer that matches mbuf_data() - mbuf_leadingspace().
 *       @param mbuf The mbuf.
 *       @result A pointer to smallest possible value for data.
 */
extern void *mbuf_datastart(mbuf_t mbuf);

/*!
 *       @function mbuf_setdata
 *       @discussion Sets the data and length values for an mbuf. The data
 *       value must be in a valid range. In the case of an mbuf with a cluster,
 *       the data value must point to a location in the cluster and the data
 *       value plus the length, must be less than the end of the cluster. For
 *       data embedded directly in an mbuf (no cluster), the data value must
 *       fall somewhere between the start and end of the data area in the
 *       mbuf and the data + length must also be in the same range.
 *       @param mbuf The mbuf.
 *       @param data The new pointer value for data.
 *       @param len The new length of data in the mbuf.
 *       @result 0 on success, errno error on failure.
 */
extern errno_t mbuf_setdata(mbuf_t mbuf, void *data, size_t len);

/*!
 *       @function mbuf_align_32
 *       @discussion mbuf_align_32 is a replacement for M_ALIGN and MH_ALIGN.
 *               mbuf_align_32 will set the data pointer to a location aligned on
 *               a four byte boundry with at least 'len' bytes between the data
 *               pointer and the end of the data block.
 *       @param mbuf The mbuf.
 *       @param len The minimum length of space that should follow the new
 *               data location.
 *       @result 0 on success, errno error on failure.
 */
extern errno_t mbuf_align_32(mbuf_t mbuf, size_t len);

/*!
 *       @function mbuf_data_to_physical
 *       @discussion mbuf_data_to_physical is a replacement for mcl_to_paddr.
 *               Given a pointer returned from mbuf_data of mbuf_datastart,
 *               mbuf_data_to_physical will return the phyical address for that
 *               block of data.  Note that even though the data is in virtually
 *               contiguous span, the underlying physical pages might not be
 *               physically contiguous.  Because of this, callers must ensure
 *               to call this routine for each page boundary.  Device drivers
 *               that deal with DMA are strongly encouraged to utilize the
 *               IOMbufNaturalMemoryCursor and walk down the list of vectors
 *               instead of using this interface to obtain the physical address.
 *               Use of this routine is therefore discouraged.
 *       @param ptr A pointer to data stored in an mbuf.
 *       @result The 64 bit physical address of the mbuf data or NULL if ptr
 *               does not point to data stored in an mbuf.
 */
extern addr64_t mbuf_data_to_physical(void *ptr);


/* Allocation */

/*!
 *       @function mbuf_get
 *       @discussion Allocates an mbuf without a cluster for external data.
 *       @param how Blocking or non-blocking.
 *       @param type The type of the mbuf.
 *       @param mbuf The mbuf.
 *       @result 0 on success, errno error on failure.
 */
extern errno_t mbuf_get(mbuf_how_t how, mbuf_type_t type, mbuf_t *mbuf);

/*!
 *       @function mbuf_gethdr
 *       @discussion Allocates an mbuf without a cluster for external data.
 *               Sets a flag to indicate there is a packet header and initializes
 *               the packet header.
 *       @param how Blocking or non-blocking.
 *       @param type The type of the mbuf.
 *       @param mbuf The mbuf.
 *       @result 0 on success, errno error on failure.
 */
extern errno_t mbuf_gethdr(mbuf_how_t how, mbuf_type_t type, mbuf_t *mbuf);

/*!
 *       @function mbuf_attachcluster
 *       @discussion Attach an external buffer as a cluster for an mbuf.  If mbuf
 *               points to a NULL mbuf_t, an mbuf will be allocated for you.  If
 *               mbuf points to a non-NULL mbuf_t, the user-supplied mbuf will
 *               be used instead.  The caller is responsible for allocating the
 *               external buffer by calling mbuf_alloccluster().
 *       @param how Blocking or non-blocking.
 *       @param type The type of the mbuf if mbuf is non-NULL; otherwise ignored.
 *       @param mbuf Pointer to the address of the mbuf; if NULL, an mbuf will
 *               be allocated, otherwise, it must point to a valid mbuf address.
 *               If the user-supplied mbuf is already attached to a cluster, the
 *               current cluster will be freed before the mbuf gets attached to
 *               the supplied external buffer.  Note that this routine may return
 *               a different mbuf_t than the one you passed in.
 *       @param extbuf Address of the external buffer.
 *       @param extfree Free routine for the external buffer; the caller is
 *               required to defined a routine that will be invoked when the
 *               mbuf is freed.
 *       @param extsize Size of the external buffer.
 *       @param extarg Private value that will be passed to the free routine
 *               when it is called at the time the mbuf is freed.
 *       @result 0 on success
 *               EINVAL - Invalid parameter
 *               ENOMEM - Not enough memory available
 */
extern errno_t mbuf_attachcluster(mbuf_how_t how, mbuf_type_t type,
    mbuf_t *mbuf, caddr_t extbuf, void (*extfree)(caddr_t, u_int, caddr_t),
    size_t extsize, caddr_t extarg);

/*!
 *       @function mbuf_alloccluster
 *       @discussion Allocate a cluster that can be later attached to an
 *               mbuf by calling mbuf_attachcluster().  The allocated cluster
 *               can also be freed (without being attached to an mbuf) by
 *               calling mbuf_freecluster().  At the moment this routine
 *               will either return a cluster of 2048, 4096 or 16384 bytes
 *               depending on the requested size.  Note that clusters greater
 *               than 4096 bytes might not be available in all configurations;
 *               the caller must additionally check for ENOTSUP (see below).
 *       @param how Blocking or non-blocking.
 *       @param size Pointer to size of requested cluster.  Sizes up to 2048
 *               will be rounded up to 2048; sizes greater than 2048 and up
 *               to 4096 will be rounded up to 4096.  Sizes greater than 4096
 *               will be rounded up to 16384.
 *       @param addr Pointer to the address of the requested cluster.
 *       @result 0 on success or ENOMEM if failure.  If the caller requests
 *               greater than 4096 bytes and the system is unable to fulfill
 *               the request due to the lack of jumbo clusters support based
 *               on the configuration, this routine will return ENOTSUP.
 *               In this case, the caller is advised to use 4096 bytes or
 *               smaller during subseqent requests.
 */
extern errno_t mbuf_alloccluster(mbuf_how_t how, size_t *size, caddr_t *addr);

/*!
 *       @function mbuf_freecluster
 *       @discussion Free a cluster that was previously allocated by a call
 *               to mbuf_alloccluster().  The caller must pass the actual
 *               size of the cluster as returned by mbuf_alloccluster(),
 *               which at this point must be either 2048, 4096 or 16384 bytes.
 *       @param addr The address of the cluster.
 *       @param size The actual size of the cluster.
 */
extern void mbuf_freecluster(caddr_t addr, size_t size);

#ifdef BSD_KERNEL_PRIVATE
/*
 * For now, restrict these to BSD kernel privates, since they are
 * used only by the Nexus netif compatibility code.
 */
extern errno_t mbuf_ring_cluster_alloc(mbuf_how_t how, mbuf_type_t type,
    mbuf_t *mbuf, void (*extfree)(caddr_t, u_int, caddr_t), size_t *size);
extern int mbuf_ring_cluster_is_active(mbuf_t mbuf);
extern errno_t mbuf_ring_cluster_activate(mbuf_t mbuf);
extern errno_t mbuf_cluster_set_prop(mbuf_t mbuf, u_int32_t oldprop,
    u_int32_t newprop);
extern errno_t mbuf_cluster_get_prop(mbuf_t mbuf, u_int32_t *prop);
#endif /* BSD_KERNEL_PRIVATE */

/*!
 *       @function mbuf_getcluster
 *       @discussion Allocate a cluster of the requested size and attach it to
 *               an mbuf for use as external data. If mbuf points to a NULL
 *               mbuf_t, an mbuf will be allocated for you. If mbuf points to
 *               a non-NULL mbuf_t, mbuf_getcluster may return a different
 *               mbuf_t than the one you passed in.
 *       @param how Blocking or non-blocking.
 *       @param type The type of the mbuf.
 *       @param size The size of the cluster to be allocated. Supported sizes
 *               for a cluster are be 2048, 4096, or 16384. Any other value
 *               with return EINVAL.  Note that clusters greater than 4096
 *               bytes might not be available in all configurations; the
 *               caller must additionally check for ENOTSUP (see below).
 *       @param mbuf The mbuf the cluster will be attached to.
 *       @result 0 on success, errno error on failure. If you specified NULL
 *               for the mbuf, any intermediate mbuf that may have been allocated
 *               will be freed. If you specify an mbuf value in *mbuf,
 *               mbuf_mclget will not free it.
 *               EINVAL - Invalid parameter
 *               ENOMEM - Not enough memory available
 *               ENOTSUP - The caller had requested greater than 4096 bytes
 *                   cluster and the system is unable to fulfill it due to the
 *                   lack of jumbo clusters support based on the configuration.
 *                   In this case, the caller is advised to use 4096 bytes or
 *                   smaller during subsequent requests.
 */
extern errno_t mbuf_getcluster(mbuf_how_t how, mbuf_type_t type, size_t size,
    mbuf_t *mbuf);

/*!
 *       @function mbuf_mclget
 *       @discussion Allocate a cluster and attach it to an mbuf for use as
 *               external data. If mbuf points to a NULL mbuf_t, an mbuf will be
 *               allocated for you. If mbuf points to a non-NULL mbuf_t,
 *               mbuf_mclget may return a different mbuf_t than the one you
 *               passed in.
 *       @param how Blocking or non-blocking.
 *       @param type The type of the mbuf.
 *       @param mbuf The mbuf the cluster will be attached to.
 *       @result 0 on success, errno error on failure. If you specified NULL
 *               for the mbuf, any intermediate mbuf that may have been allocated
 *               will be freed. If you specify an mbuf value in *mbuf,
 *               mbuf_mclget will not free it.
 */
extern errno_t mbuf_mclget(mbuf_how_t how, mbuf_type_t type, mbuf_t *mbuf);

/*!
 *       @function mbuf_allocpacket
 *       @discussion Allocate an mbuf chain to store a single packet of the
 *               requested length.  According to the requested length, a chain
 *               of mbufs will be created. The mbuf type will be set to
 *               MBUF_TYPE_DATA. The caller may specify the maximum number of
 *               buffer.
 *       @param how Blocking or non-blocking
 *       @param packetlen The total length of the packet mbuf to be allocated.
 *               The length must be greater than zero.
 *       @param maxchunks An input/output pointer to the maximum number of mbufs
 *               segments making up the chain.  On input, if maxchunks is NULL,
 *               or the value pointed to by maxchunks is zero, the packet will
 *               be made up of as few or as many buffer segments as necessary
 *               to fit the length.  The allocation will fail with ENOBUFS if
 *               the number of segments requested is too small and the sum of
 *               the maximum size of each individual segment is less than the
 *               packet length.  On output, if the allocation succeed and
 *               maxchunks is non-NULL, it will point to the actual number
 *               of segments allocated.
 *               Additional notes for packetlen greater than 4096 bytes:
 *               the caller may pass a non-NULL maxchunks and initialize it
 *               with zero such that upon success, it can find out whether
 *               or not the system configuration allows for larger than
 *               4096 bytes cluster allocations, by checking on the value
 *               pointed to by maxchunks.  E.g. a request for 9018 bytes may
 *               result in 1 chunk when jumbo clusters are available, or
 *               3 chunks otherwise.
 *       @param mbuf Upon success, *mbuf will be a reference to the new mbuf.
 *       @result Returns 0 upon success or the following error code:
 *               EINVAL - Invalid parameter
 *               ENOMEM - Not enough memory available
 *               ENOBUFS - Buffers not big enough for the maximum number of
 *                   chunks requested
 */
extern errno_t mbuf_allocpacket(mbuf_how_t how, size_t packetlen,
    unsigned int * maxchunks, mbuf_t *mbuf);

/*!
 *       @function mbuf_allocpacket_list
 *       @discussion Allocate a linked list of packets.  According to the
 *               requested length, each packet will made of a chain of one
 *               or more mbufs.  The mbuf type will be set to MBUF_TYPE_DATA.
 *               The caller may specify the maximum number of element for
 *               each mbuf chain making up a packet.
 *       @param numpkts Number of packets to allocate
 *       @param how Blocking or non-blocking
 *       @param packetlen The total length of the packet mbuf to be allocated.
 *               The length must be greater than zero.
 *       @param maxchunks An input/output pointer to the maximum number of
 *               mbufs segments making up the chain.  On input, if maxchunks is
 *               zero, or the value pointed to by maxchunks is zero, the packet
 *               will be made of as few or as many buffer segments as necessary
 *               to fit the length.  The allocation will fail with ENOBUFS if
 *               the number of segments requested is too small and the sum of
 *               the maximum size of each individual segment is less than the
 *               packet length.  On output, if the allocation succeed and
 *               maxchunks is non zero, it will point to the actual number
 *               of segments allocated.
 *               Additional notes for packetlen greater than 4096 bytes:
 *               the caller may pass a non-NULL maxchunks and initialize it
 *               with zero such that upon success, it can find out whether
 *               or not the system configuration allows for larger than
 *               4096 bytes cluster allocations, by checking on the value
 *               pointed to by maxchunks.  E.g. a request for 9018 bytes may
 *               result in 1 chunk when jumbo clusters are available, or
 *               3 chunks otherwise.
 *       @param mbuf Upon success, *mbuf will be a reference to the new mbuf.
 *       @result Returns 0 upon success or the following error code:
 *               EINVAL - Invalid parameter
 *               ENOMEM - Not enough memory available
 *               ENOBUFS - Buffers not big enough for the maximum number of
 *                   chunks requested
 */
extern errno_t mbuf_allocpacket_list(unsigned int numpkts, mbuf_how_t how,
    size_t packetlen, unsigned int * maxchunks, mbuf_t *mbuf);


/*!
 *       @function mbuf_getpacket
 *       @discussion Allocate an mbuf, allocate and attach a cluster, and set
 *               the packet header flag.
 *       @param how Blocking or non-blocking.
 *       @param mbuf Upon success, *mbuf will be a reference to the new mbuf.
 *       @result 0 on success, errno error on failure.
 */
extern errno_t mbuf_getpacket(mbuf_how_t how, mbuf_t *mbuf);

/*!
 *       @function mbuf_free
 *       @discussion Frees a single mbuf. Not commonly used because it
 *               doesn't touch the rest of the mbufs on the chain.
 *       @param mbuf The mbuf to free.
 *       @result The next mbuf in the chain.
 */
extern mbuf_t mbuf_free(mbuf_t mbuf);

/*!
 *       @function mbuf_freem
 *       @discussion Frees a chain of mbufs link through mnext.
 *       @param mbuf The first mbuf in the chain to free.
 */
extern void mbuf_freem(mbuf_t mbuf);

/*!
 *       @function mbuf_freem_list
 *       @discussion Frees linked list of mbuf chains. Walks through
 *               mnextpackt and does the equivalent of mbuf_freem to each.
 *       @param mbuf The first mbuf in the linked list to free.
 *       @result The number of mbufs freed.
 */
extern int mbuf_freem_list(mbuf_t mbuf);

/*!
 *       @function mbuf_leadingspace
 *       @discussion Determines the space available in the mbuf proceeding
 *               the current data.
 *       @param mbuf The mbuf.
 *       @result The number of unused bytes at the start of the mbuf.
 */
extern size_t mbuf_leadingspace(const mbuf_t mbuf);

/*!
 *       @function mbuf_trailingspace
 *       @discussion Determines the space available in the mbuf following
 *               the current data.
 *       @param mbuf The mbuf.
 *       @result The number of unused bytes following the current data.
 */
extern size_t mbuf_trailingspace(const mbuf_t mbuf);

/* Manipulation */

/*!
 *       @function mbuf_copym
 *       @discussion Copies len bytes from offset from src to a new mbuf.  If
 *           the original mbuf contains a packet header, the new mbuf will
 *           contain similar packet header except for any tags which may be
 *           associated with the original mbuf.  mbuf_dup() should be used
 *           instead if tags are to be copied to the new mbuf.
 *       @param src The source mbuf.
 *       @param offset The offset in the mbuf to start copying from.
 *       @param len The the number of bytes to copy.
 *       @param how To block or not to block, that is a question.
 *       @param new_mbuf Upon success, the newly allocated mbuf.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_copym(const mbuf_t src, size_t offset, size_t len,
    mbuf_how_t how, mbuf_t *new_mbuf);

/*!
 *       @function mbuf_dup
 *       @discussion Exactly duplicates an mbuf chain.  If the original mbuf
 *           contains a packet header (including tags), the new mbuf will have
 *           the same packet header contents and a copy of each tag associated
 *           with the original mbuf.
 *       @param src The source mbuf.
 *       @param how Blocking or non-blocking.
 *       @param new_mbuf Upon success, the newly allocated mbuf.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_dup(const mbuf_t src, mbuf_how_t how, mbuf_t *new_mbuf);

/*!
 *       @function mbuf_prepend
 *       @discussion Prepend len bytes to an mbuf. If there is space
 *               (mbuf_leadingspace >= len), the mbuf's data ptr is changed and
 *               the same mbuf is returned. If there is no space, a new mbuf may
 *               be allocated and prepended to the mbuf chain. If the operation
 *               fails, the mbuf may be freed (*mbuf will be NULL).
 *       @param mbuf The mbuf to prepend data to. This may change if a new
 *               mbuf must be allocated or may be NULL if the operation fails.
 *       @param len The length, in bytes, to be prepended to the mbuf.
 *       @param how Blocking or non-blocking.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_prepend(mbuf_t *mbuf, size_t len, mbuf_how_t how);

/*!
 *       @function mbuf_split
 *       @discussion Split an mbuf chain at a specific offset.
 *       @param src The mbuf to be split.
 *       @param offset The offset in the buffer where the mbuf should be
 *               split.
 *       @param how Blocking or non-blocking.
 *       @param new_mbuf Upon success, the second half of the split mbuf
 *               chain.
 *       @result 0 upon success otherwise the errno error. In the case of
 *               failure, the original mbuf chain passed in to src will be
 *               preserved.
 */
extern errno_t mbuf_split(mbuf_t src, size_t offset, mbuf_how_t how,
    mbuf_t *new_mbuf);

/*!
 *       @function mbuf_pullup
 *       @discussion Move the next len bytes in to mbuf from other mbufs in
 *               the chain. This is commonly used to get the IP and TCP or UDP
 *               header contiguous in the first mbuf. If mbuf_pullup fails, the
 *               entire mbuf chain will be freed.
 *       @param mbuf The mbuf in the chain the data should be contiguous in.
 *       @param len The number of bytes to pull from the next mbuf(s).
 *       @result 0 upon success otherwise the errno error. In the case of an
 *               error, the mbuf chain has been freed.
 */
extern errno_t mbuf_pullup(mbuf_t *mbuf, size_t len);

/*!
 *       @function mbuf_pulldown
 *       @discussion Make length bytes at offset in the mbuf chain
 *               contiguous. Nothing before offset bytes in the chain will be
 *               modified. Upon return, location will be the mbuf the data is
 *               contiguous in and offset will be the offset in that mbuf at
 *               which the data is located.  In the case of a failure, the mbuf
 *               chain will be freed.
 *       @param src The start of the mbuf chain.
 *       @param offset Pass in a pointer to a value with the offset of the
 *               data you're interested in making contiguous. Upon success, this
 *               will be overwritten with the offset from the mbuf returned in
 *               location.
 *       @param length The length of data that should be made contiguous.
 *       @param location Upon success, *location will be the mbuf the data is
 *               in.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_pulldown(mbuf_t src, size_t *offset, size_t length,
    mbuf_t *location);

/*!
 *       @function mbuf_adj
 *       @discussion Trims len bytes from the mbuf. If the length is greater
 *               than zero, the bytes are trimmed from the front of the mbuf. If
 *               the length is less than zero, the bytes are trimmed from the end
 *               of the mbuf chain.
 *       @param mbuf The mbuf chain to trim.
 *       @param len The number of bytes to trim from the mbuf chain.
 */
extern void mbuf_adj(mbuf_t mbuf, int len);

/*!
 *       @function mbuf_adjustlen
 *       @discussion Adds amount to the mbuf len. Verifies that the new
 *               length is valid (greater than or equal to zero and less than
 *               maximum amount of data that may be stored in the mbuf). This
 *               function will not adjust the packet header length field or
 *               affect any other mbufs in a chain.
 *       @param mbuf The mbuf to adjust.
 *       @param amount The number of bytes increment the length by.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_adjustlen(mbuf_t mbuf, int amount);

/*!
 *       @function mbuf_concatenate
 *       @discussion Concatenate mbuf chain src to dst using m_next and return
 *               a chain which represents the concatenated chain.  The routine
 *               does not prevent two chains of different mbuf types to be
 *               concatenated, nor does it modify any packet header in the
 *               destination chain.  Therefore, it's the responsibility of the
 *               caller to ensure that the resulted concatenated mbuf chain is
 *               correct for further usages.
 *       @param dst The destination mbuf chain.
 *       @param src The source mbuf chain.
 *       @result A pointer to the head of the concatenated mbuf chain.  This
 *               should be treated as the updated destination mbuf chain; the
 *               caller must no longer refer to the original src or dst mbuf
 *               chain.  Otherwise it returns NULL if the original dst mbuf
 *               chain is NULL.
 */
extern mbuf_t mbuf_concatenate(mbuf_t dst, mbuf_t src);

/*!
 *       @function mbuf_copydata
 *       @discussion Copies data out of an mbuf in to a specified buffer. If
 *               the data is stored in a chain of mbufs, the data will be copied
 *               from each mbuf in the chain until length bytes have been copied.
 *       @param mbuf The mbuf chain to copy data out of.
 *       @param offset The offset in to the mbuf to start copying.
 *       @param length The number of bytes to copy.
 *       @param out_data A pointer to the location where the data will be
 *               copied.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_copydata(const mbuf_t mbuf, size_t offset, size_t length,
    void *out_data);

/*!
 *       @function mbuf_copyback
 *       @discussion Copies data from a buffer to an mbuf chain.
 *               mbuf_copyback will grow the chain to fit the specified buffer.
 *
 *               If mbuf_copydata is unable to allocate enough mbufs to grow the
 *               chain, ENOBUFS will be returned. The mbuf chain will be shorter
 *               than expected but all of the data up to the end of the mbuf
 *               chain will be valid.
 *
 *               If an offset is specified, mbuf_copyback will skip that many
 *               bytes in the mbuf chain before starting to write the buffer in
 *               to the chain. If the mbuf chain does not contain this many
 *               bytes, mbufs will be allocated to create the space.
 *       @param mbuf The first mbuf in the chain to copy the data in to.
 *       @param offset Offset in bytes to skip before copying data.
 *       @param length The length, in bytes, of the data to copy in to the mbuf
 *               chain.
 *       @param data A pointer to data in the kernel's address space.
 *       @param how Blocking or non-blocking.
 *       @result 0 upon success, EINVAL or ENOBUFS upon failure.
 */
extern errno_t mbuf_copyback(mbuf_t mbuf, size_t offset, size_t length,
    const void *data, mbuf_how_t how);

/*!
 *       @function mbuf_mclhasreference
 *       @discussion Check if a cluster of an mbuf is referenced by another mbuf.
 *               References may be taken, for example, as a result of a call to
 *               mbuf_split or mbuf_copym
 *       @param mbuf The mbuf with the cluster to test.
 *       @result 0 if there is no reference by another mbuf, 1 otherwise.
 */
extern int mbuf_mclhasreference(mbuf_t mbuf);


/* mbuf header */

/*!
 *       @function mbuf_next
 *       @discussion Returns the next mbuf in the chain.
 *       @param mbuf The mbuf.
 *       @result The next mbuf in the chain.
 */
extern mbuf_t mbuf_next(const mbuf_t mbuf);

/*!
 *       @function mbuf_setnext
 *       @discussion Sets the next mbuf in the chain.
 *       @param mbuf The mbuf.
 *       @param next The new next mbuf.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_setnext(mbuf_t mbuf, mbuf_t next);

/*!
 *       @function mbuf_nextpkt
 *       @discussion Gets the next packet from the mbuf.
 *       @param mbuf The mbuf.
 *       @result The nextpkt.
 */
extern mbuf_t mbuf_nextpkt(const mbuf_t mbuf);

/*!
 *       @function mbuf_setnextpkt
 *       @discussion Sets the next packet attached to this mbuf.
 *       @param mbuf The mbuf.
 *       @param nextpkt The new next packet.
 */
extern void mbuf_setnextpkt(mbuf_t mbuf, mbuf_t nextpkt);

/*!
 *       @function mbuf_len
 *       @discussion Gets the length of data in this mbuf.
 *       @param mbuf The mbuf.
 *       @result The length.
 */
extern size_t mbuf_len(const mbuf_t mbuf);

/*!
 *       @function mbuf_setlen
 *       @discussion Sets the length of data in this packet. Be careful to
 *               not set the length over the space available in the mbuf.
 *       @param mbuf The mbuf.
 *       @param len The new length.
 */
extern void mbuf_setlen(mbuf_t mbuf, size_t len);

/*!
 *       @function mbuf_maxlen
 *       @discussion Retrieves the maximum length of data that may be stored
 *               in this mbuf. This value assumes that the data pointer was set
 *               to the start of the possible range for that pointer
 *               (mbuf_data_start).
 *       @param mbuf The mbuf.
 *       @result The maximum lenght of data for this mbuf.
 */
extern size_t mbuf_maxlen(const mbuf_t mbuf);

/*!
 *       @function mbuf_type
 *       @discussion Gets the type of mbuf.
 *       @param mbuf The mbuf.
 *       @result The type.
 */
extern mbuf_type_t mbuf_type(const mbuf_t mbuf);

/*!
 *       @function mbuf_settype
 *       @discussion Sets the type of mbuf.
 *       @param mbuf The mbuf.
 *       @param new_type The new type.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_settype(mbuf_t mbuf, mbuf_type_t new_type);

/*!
 *       @function mbuf_flags
 *       @discussion Returns the set flags.
 *       @param mbuf The mbuf.
 *       @result The flags.
 */
extern mbuf_flags_t mbuf_flags(const mbuf_t mbuf);

/*!
 *       @function mbuf_setflags
 *       @discussion Sets the set of set flags.
 *       @param mbuf The mbuf.
 *       @param flags The flags that should be set, all other flags will be
 *               cleared.  Certain flags such as MBUF_EXT cannot be altered.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_setflags(mbuf_t mbuf, mbuf_flags_t flags);

/*!
 *       @function mbuf_setflags_mask
 *       @discussion Useful for setting or clearing individual flags. Easier
 *               than calling mbuf_setflags(m, mbuf_flags(m) | M_FLAG).
 *       @param mbuf The mbuf.
 *       @param flags The flags that should be set or cleared.  Certain flags
 *               such as MBUF_EXT cannot be altered.
 *       @param mask The mask controlling which flags will be modified.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_setflags_mask(mbuf_t mbuf, mbuf_flags_t flags,
    mbuf_flags_t mask);

/*!
 *       @function mbuf_copy_pkthdr
 *       @discussion Copies the packet header from src to dest.
 *       @param src The mbuf from which the packet header will be copied.
 *       @param dest The mbuf to which the packet header will be copied.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_copy_pkthdr(mbuf_t dest, const mbuf_t src);

/*!
 *       @function mbuf_pkthdr_len
 *       @discussion Returns the length as reported by the packet header.
 *       @param mbuf The mbuf containing the packet header
 *       @result The length, in bytes, of the packet.
 */
extern size_t mbuf_pkthdr_len(const mbuf_t mbuf);

/*!
 *       @function mbuf_pkthdr_setlen
 *       @discussion Sets the length of the packet in the packet header.
 *       @param mbuf The mbuf containing the packet header.
 *       @param len The new length of the packet.
 */
extern void mbuf_pkthdr_setlen(mbuf_t mbuf, size_t len);

#ifdef XNU_KERNEL_PRIVATE
/*!
 *       @function mbuf_pkthdr_maxlen
 *       @discussion Retrieves the maximum length of data that may be stored
 *               in this mbuf packet. This value assumes that the data pointer
 *                was set to the start of the possible range for that pointer
 *               for each mbuf in the packet chain
 *       @param mbuf The mbuf.
 *       @result The maximum lenght of data for this mbuf.
 */
extern size_t mbuf_pkthdr_maxlen(const mbuf_t mbuf);
#endif /* XNU_KERNEL_PRIVATE */

/*!
 *       @function mbuf_pkthdr_adjustlen
 *       @discussion Adjusts the length of the packet in the packet header.
 *       @param mbuf The mbuf containing the packet header.
 *       @param amount The number of bytes to adjust the packet header length
 *               field by.
 */
extern void mbuf_pkthdr_adjustlen(mbuf_t mbuf, int amount);

/*!
 *       @function mbuf_pkthdr_rcvif
 *       @discussion Returns the interface the packet was received on. This
 *               funciton does not modify the reference count of the interface.
 *               The interface is only valid for as long as the mbuf is not freed
 *               and the rcvif for the mbuf is not changed. Take a reference on
 *               the interface that you will release later before doing any of
 *               the following: free the mbuf, change the rcvif, pass the mbuf to
 *               any function that may free the mbuf or change the rcvif.
 *       @param mbuf The mbuf containing the packet header.
 *       @result A reference to the interface.
 */
extern ifnet_t mbuf_pkthdr_rcvif(const mbuf_t mbuf);

/*!
 *       @function mbuf_pkthdr_setrcvif
 *       @discussion Sets the interface the packet was received on.
 *       @param mbuf The mbuf containing the packet header.
 *       @param ifp A reference to an interface.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_pkthdr_setrcvif(mbuf_t mbuf, ifnet_t ifp);

/*!
 *       @function mbuf_pkthdr_header
 *       @discussion Returns a pointer to the packet header.
 *       @param mbuf The mbuf containing the packet header.
 *       @result A pointer to the packet header.
 */
extern void *mbuf_pkthdr_header(const mbuf_t mbuf);

/*!
 *       @function mbuf_pkthdr_setheader
 *       @discussion Sets the pointer to the packet header.
 *       @param mbuf The mbuf containing the packet header.
 *       @param header A pointer to the header.
 */
extern void mbuf_pkthdr_setheader(mbuf_t mbuf, void *header);

/* Checksums */

/*!
 *       @function mbuf_inbound_modified
 *       @discussion This function will clear the checksum flags to indicate
 *               that a hardware checksum should not be used. Any filter
 *               modifying data should call this function on an mbuf before
 *               passing the packet up the stack. If a filter modifies a packet
 *               in a way that affects any checksum, the filter is responsible
 *               for either modifying the checksum to compensate for the changes
 *               or verifying the checksum before making the changes and then
 *               modifying the data and calculating a new checksum only if the
 *               original checksum was valid.
 *       @param mbuf The mbuf that has been modified.
 */
extern void mbuf_inbound_modified(mbuf_t mbuf);

/*!
 *       @function mbuf_outbound_finalize
 *       @discussion This function will "finalize" the packet allowing your
 *               code to inspect the final packet.
 *
 *               There are a number of operations that are performed in hardware,
 *               such as calculating checksums. This function will perform in
 *               software the various opterations that were scheduled to be done
 *               in hardware. Future operations may include IPsec processing or
 *               vlan support. If you are redirecting a packet to a new interface
 *               which may not have the same hardware support or encapsulating
 *               the packet, you should call this function to force the stack to
 *               calculate and fill out the checksums. This will bypass hardware
 *               checksums but give you a complete packet to work with. If you
 *               need to inspect aspects of the packet which may be generated by
 *               hardware, you must call this function to get an aproximate final
 *               packet. If you plan to modify the packet in any way, you should
 *               call this function.
 *
 *               This function should be called before modifying any outbound
 *               packets.
 *
 *               This function may be called at various levels, in some cases
 *               additional headers may have already been prepended, such as the
 *               case of a packet seen by an interface filter. To handle this,
 *               the caller must pass the protocol family of the packet as well
 *               as the offset from the start of the packet to the protocol
 *               header.
 *       @param mbuf The mbuf that should be finalized.
 *       @param protocol_family The protocol family of the packet in the
 *               mbuf.
 *       @param protocol_offset The offset from the start of the mbuf to the
 *               protocol header. For an IP packet with an ethernet header, this
 *               would be the length of an ethernet header.
 */
extern void mbuf_outbound_finalize(mbuf_t mbuf, u_int32_t protocol_family,
    size_t protocol_offset);

/*!
 *       @function mbuf_set_vlan_tag
 *       @discussion This function is used by interfaces that support vlan
 *               tagging in hardware. This function will set properties in the
 *               mbuf to indicate which vlan the packet was received for.
 *       @param mbuf The mbuf containing the packet.
 *       @param vlan The protocol family of the aux data to add.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_set_vlan_tag(mbuf_t mbuf, u_int16_t vlan);

/*!
 *       @function mbuf_get_vlan_tag
 *       @discussion This function is used by drivers that support hardware
 *               vlan tagging to determine which vlan this packet belongs to. To
 *               differentiate between the case where the vlan tag is zero and
 *               the case where there is no vlan tag, this function will return
 *               ENXIO when there is no vlan.
 *       @param mbuf The mbuf containing the packet.
 *       @param vlan The protocol family of the aux data to add.
 *       @result 0 upon success otherwise the errno error. ENXIO indicates
 *               that the vlan tag is not set.
 */
extern errno_t mbuf_get_vlan_tag(mbuf_t mbuf, u_int16_t *vlan);

/*!
 *       @function mbuf_clear_vlan_tag
 *       @discussion This function will clear any vlan tag associated with
 *               the mbuf.
 *       @param mbuf The mbuf containing the packet.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_clear_vlan_tag(mbuf_t mbuf);

#ifdef KERNEL_PRIVATE
/*!
 *       @function mbuf_set_csum_requested
 *       @discussion This function is used by the stack to indicate which
 *               checksums should be calculated in hardware. The stack normally
 *               sets these flags as the packet is processed in the outbound
 *               direction. Just before send the packe to the interface, the
 *               stack will look at these flags and perform any checksums in
 *               software that are not supported by the interface.
 *       @param mbuf The mbuf containing the packet.
 *       @param request Flags indicating which checksums are being requested
 *               for this packet.
 *       @param value This parameter is currently unsupported.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_set_csum_requested(mbuf_t mbuf,
    mbuf_csum_request_flags_t request, u_int32_t value);
#endif /* KERNEL_PRIVATE */

/*!
 *       @function mbuf_get_csum_requested
 *       @discussion This function is used by the driver to determine which
 *               checksum operations should be performed in hardware.
 *       @param mbuf The mbuf containing the packet.
 *       @param request Flags indicating which checksums are being requested
 *               for this packet.
 *       @param value This parameter is currently unsupported.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_get_csum_requested(mbuf_t mbuf,
    mbuf_csum_request_flags_t *request, u_int32_t *value);

/*!
 *       @function mbuf_get_tso_requested
 *       @discussion This function is used by the driver to determine which
 *               checksum operations should be performed in hardware.
 *       @param mbuf The mbuf containing the packet.
 *       @param request Flags indicating which values are being requested
 *               for this packet.
 *       @param value The requested value.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_get_tso_requested(mbuf_t mbuf,
    mbuf_tso_request_flags_t *request, u_int32_t *value);

/*!
 *       @function mbuf_clear_csum_requested
 *       @discussion This function clears the checksum request flags.
 *       @param mbuf The mbuf containing the packet.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_clear_csum_requested(mbuf_t mbuf);

/*!
 *       @function mbuf_set_csum_performed
 *       @discussion This is used by the driver to indicate to the stack which
 *               checksum operations were performed in hardware.
 *       @param mbuf The mbuf containing the packet.
 *       @param flags Flags indicating which hardware checksum operations
 *               were performed.
 *       @param value If the MBUF_CSUM_DID_DATA flag is set, value should be
 *               set to the value of the TCP or UDP header as calculated by the
 *               hardware.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_set_csum_performed(mbuf_t mbuf,
    mbuf_csum_performed_flags_t flags, u_int32_t value);

#ifdef KERNEL_PRIVATE
/*
 *       @function mbuf_get_csum_performed
 *       @discussion This is used by the stack to determine which checksums
 *               were calculated in hardware on the inbound path.
 *       @param mbuf The mbuf containing the packet.
 *       @param flags Flags indicating which hardware checksum operations
 *               were performed.
 *       @param value If the MBUF_CSUM_DID_DATA flag is set, value will be
 *               set to the value of the TCP or UDP header as calculated by the
 *               hardware.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_get_csum_performed(mbuf_t mbuf,
    mbuf_csum_performed_flags_t *flags, u_int32_t *value);
#endif /* KERNEL_PRIVATE */

/*!
 *       @function mbuf_get_mlen
 *       @discussion This routine returns the number of data bytes in a normal
 *               mbuf, i.e. an mbuf that is not a packet header, nor one with
 *               an external cluster attached to it.  This is equivalent to the
 *               legacy MLEN macro.
 *       @result	The number of bytes of available data.
 */
extern u_int32_t mbuf_get_mlen(void);

/*!
 *       @function mbuf_get_mhlen
 *       @discussion This routine returns the number of data bytes in a packet
 *               header mbuf.  This is equivalent to the legacy MHLEN macro.
 *       @result	The number of bytes of available data.
 */
extern u_int32_t mbuf_get_mhlen(void);

/*!
 *       @function mbuf_get_minclsize
 *       @discussion This routine returns the minimum number of data bytes
 *               before an external cluster is used.  This is equivalent to the
 *               legacy MINCLSIZE macro.
 *       @result	The minimum number of bytes before a cluster will be used.
 */
extern u_int32_t mbuf_get_minclsize(void);

/*!
 *       @function mbuf_clear_csum_performed
 *       @discussion Clears the hardware checksum flags and values.
 *       @param mbuf The mbuf containing the packet.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_clear_csum_performed(mbuf_t mbuf);

/*!
 *       @function mbuf_inet_cksum
 *       @discussion Calculates 16-bit 1's complement Internet checksum of the
 *               transport segment with or without the pseudo header checksum
 *               of a given IPv4 packet.  If the caller specifies a non-zero
 *               transport protocol, the checksum returned will also include
 *               the pseudo header checksum for the corresponding transport
 *               header.  Otherwise, no header parsing will be done and the
 *               caller may use this to calculate the Internet checksum of
 *               an arbitrary span of data.
 *
 *               This routine does not modify the contents of the packet.  If
 *               the caller specifies a non-zero protocol and/or offset, the
 *               routine expects the complete protocol header to be present
 *               at the beginning of the first mbuf.
 *       @param mbuf The mbuf (or chain of mbufs) containing the packet.
 *       @param protocol A zero or non-zero value.  A non-zero value specifies
 *               the transport protocol used for pseudo header checksum.
 *       @param offset A zero or non-zero value; if the latter, it specifies
 *               the offset of the transport header from the beginning of mbuf.
 *       @param length The total (non-zero) length of the transport segment.
 *       @param csum Pointer to the checksum variable; upon success, this
 *               routine will return the calculated Internet checksum through
 *               this variable.  The caller must set it to a non-NULL value.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_inet_cksum(mbuf_t mbuf, int protocol, u_int32_t offset,
    u_int32_t length, u_int16_t *csum);

/*!
 *       @function mbuf_inet6_cksum
 *       @discussion Calculates 16-bit 1's complement Internet checksum of the
 *               transport segment with or without the pseudo header checksum
 *               of a given IPv6 packet.  If the caller specifies a non-zero
 *               transport protocol, the checksum returned will also include
 *               the pseudo header checksum for the corresponding transport
 *               header.  Otherwise, no header parsing will be done and the
 *               caller may use this to calculate the Internet checksum of
 *               an arbitrary span of data.
 *
 *               This routine does not modify the contents of the packet.  If
 *               the caller specifies a non-zero protocol and/or offset, the
 *               routine expects the complete protocol header(s) to be present
 *               at the beginning of the first mbuf.
 *       @param mbuf The mbuf (or chain of mbufs) containing the packet.
 *       @param protocol A zero or non-zero value.  A non-zero value specifies
 *               the transport protocol used for pseudo header checksum.
 *       @param offset A zero or non-zero value; if the latter, it specifies
 *               the offset of the transport header from the beginning of mbuf.
 *       @param length The total (non-zero) length of the transport segment.
 *       @param csum Pointer to the checksum variable; upon success, this
 *               routine will return the calculated Internet checksum through
 *               this variable.  The caller must set it to a non-NULL value.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_inet6_cksum(mbuf_t mbuf, int protocol, u_int32_t offset,
    u_int32_t length, u_int16_t *csum);

/* mbuf tags */

/*!
 *       @function mbuf_tag_id_find
 *       @discussion Lookup the module id for a string. If there is no module
 *               id assigned to this string, a new module id will be assigned.
 *               The string should be the bundle id of the kext. In the case of a
 *               tag that will be shared across multiple kexts, a common bundle
 *               id style string should be used.
 *
 *               The lookup operation is not optimized. A module should call this
 *               function once during startup and chache the module id. The
 *               module id will not be resassigned until the machine reboots.
 *       @param module_string A unique string identifying your module.
 *               Example: com.apple.nke.SharedIP.
 *       @param module_id Upon return, a unique identifier for use with
 *               mbuf_tag_* functions. This identifier is valid until the machine
 *               is rebooted.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_tag_id_find(const char *module_string,
    mbuf_tag_id_t *module_id);

/*!
 *       @function mbuf_tag_allocate
 *       @discussion Allocate an mbuf tag. Mbuf tags allow various portions
 *               of the stack to tag mbufs with data that will travel with the
 *               mbuf through the stack.
 *
 *               Tags may only be added to mbufs with packet headers
 *               (MBUF_PKTHDR flag is set). Mbuf tags are freed when the mbuf is
 *               freed or when mbuf_tag_free is called.
 *       @param mbuf The mbuf to attach this tag to.
 *       @param module_id A module identifier returned by mbuf_tag_id_find.
 *       @param type A 16 bit type value. For a given module_id, you can use
 *               a number of different tag types.
 *       @param length The length, in bytes, to allocate for storage that
 *               will be associated with this tag on this mbuf.
 *       @param how Indicate whether you want to block and wait for memory if
 *               memory is not immediately available.
 *       @param data_p Upon successful return, *data_p will point to the
 *               buffer allocated for the mtag.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_tag_allocate(mbuf_t mbuf, mbuf_tag_id_t module_id,
    mbuf_tag_type_t type, size_t length, mbuf_how_t how, void **data_p);

/*!
 *       @function mbuf_tag_find
 *       @discussion Find the data associated with an mbuf tag.
 *       @param mbuf The mbuf the tag is attached to.
 *       @param module_id A module identifier returned by mbuf_tag_id_find.
 *       @param type The 16 bit type of the tag to find.
 *       @param length Upon success, the length of data will be store in
 * length.
 *       @param data_p Upon successful return, *data_p will point to the
 *               buffer allocated for the mtag.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_tag_find(mbuf_t mbuf, mbuf_tag_id_t module_id,
    mbuf_tag_type_t type, size_t *length, void **data_p);

/*!
 *       @function mbuf_tag_free
 *       @discussion Frees a previously allocated mbuf tag.
 *       @param mbuf The mbuf the tag was allocated on.
 *       @param module_id The ID of the tag to free.
 *       @param type The type of the tag to free.
 */
extern void mbuf_tag_free(mbuf_t mbuf, mbuf_tag_id_t module_id,
    mbuf_tag_type_t type);

#ifdef KERNEL_PRIVATE
/*!
 *       @function mbuf_add_drvaux
 *       @discussion Allocate space for driver auxiliary data and attach it
 *               to the packet (MBUF_PKTHDR is required.)  This space is freed
 *               when the mbuf is freed or when mbuf_del_drvaux is called.
 *               Only one instance of driver auxiliary data may be attached to
 *               a packet. Any attempt to add it to a packet already associated
 *               with one will yield an error, and the existing one must first
 *               be removed via mbuf_del_drvaux.  The format and length of the
 *               data depend largely on the family and sub-family.  The system
 *               makes no attempt to define and/or interpret the contents of
 *               the data, and simply acts as a conduit between its producer
 *               and consumer.
 *       @param mbuf The mbuf to attach the auxiliary data to.
 *       @param how Indicate whether you are willing to block and wait for
 *               memory, if memory is not immediately available.
 *       @param family The interface family as defined in net/kpi_interface.h.
 *       @param subfamily The interface sub-family as defined in
 *               net/kpi_interface.h.
 *       @param length The length of the auxiliary data, must be greater than 0.
 *       @param data_p Upon successful return, *data_p will point to the
 *               space allocated for the data.  Caller may set this to NULL.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_add_drvaux(mbuf_t mbuf, mbuf_how_t how,
    u_int32_t family, u_int32_t subfamily, size_t length, void **data_p);

/*!
 *       @function mbuf_find_drvaux
 *       @discussion Find the driver auxiliary data associated with a packet.
 *       @param mbuf The mbuf the auxiliary data is attached to.
 *       @param family_p Upon successful return, *family_p will contain
 *               the interface family associated with the data, as defined
 *               in net/kpi_interface.h.  Caller may set this to NULL.
 *       @param subfamily_p Upon successful return, *subfamily_p will contain
 *               the interface family associated with the data, as defined
 *               in net/kpi_interface.h.  Caller may set this to NULL.
 *       @param length_p Upon successful return, *length_p will contain
 *               the length of the driver auxiliary data.  Caller may
 *               set this to NULL.
 *       @param data_p Upon successful return, *data_p will point to the
 *               space allocated for the data.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_find_drvaux(mbuf_t mbuf, u_int32_t *family_p,
    u_int32_t *subfamily_p, u_int32_t *length_p, void **data_p);

/*!
 *       @function mbuf_del_drvaux
 *       @discussion Remove and free any driver auxility data associated
 *               with the packet.
 *       @param mbuf The mbuf the auxiliary data is attached to.
 */
extern void mbuf_del_drvaux(mbuf_t mbuf);
#endif /* KERNEL_PRIVATE */

/* mbuf stats */

/*!
 *       @function mbuf_stats
 *       @discussion Get the mbuf statistics.
 *       @param stats Storage to copy the stats in to.
 */
extern void mbuf_stats(struct mbuf_stat *stats);


/*!
 *       @enum mbuf_traffic_class_t
 *       @abstract Traffic class of a packet
 *       @discussion Property that represent the category of traffic of a packet.
 *               This information may be used by the driver and at the link level.
 *       @constant MBUF_TC_BE Best effort, normal class.
 *       @constant MBUF_TC_BK Background, low priority or bulk traffic.
 *       @constant MBUF_TC_VI Interactive video, constant bit rate, low latency.
 *       @constant MBUF_TC_VO Interactive voice, constant bit rate, lowest latency.
 */
typedef enum {
#ifdef XNU_KERNEL_PRIVATE
	MBUF_TC_UNSPEC  = -1,           /* Internal: not specified */
#endif
	MBUF_TC_BE              = 0,
	MBUF_TC_BK              = 1,
	MBUF_TC_VI              = 2,
	MBUF_TC_VO              = 3
#ifdef XNU_KERNEL_PRIVATE
	,
	MBUF_TC_MAX             = 4     /* Internal: traffic class count */
#endif
} mbuf_traffic_class_t;

/*!
 *       @function mbuf_get_traffic_class
 *       @discussion Get the traffic class of an mbuf packet
 *       @param mbuf The mbuf to get the traffic class of.
 *       @result The traffic class
 */
extern mbuf_traffic_class_t mbuf_get_traffic_class(mbuf_t mbuf);

/*!
 *       @function mbuf_set_traffic_class
 *       @discussion Set the traffic class of an mbuf packet.
 *       @param mbuf The mbuf to set the traffic class on.
 *       @param tc The traffic class
 *       @result 0 on success, EINVAL if bad parameter is passed
 */
extern errno_t mbuf_set_traffic_class(mbuf_t mbuf, mbuf_traffic_class_t tc);

/*!
 *       @function mbuf_is_traffic_class_privileged
 *       @discussion Returns the privileged status of the traffic class
 *               of the packet specified by the mbuf.
 *       @param mbuf The mbuf to retrieve the status from.
 *       @result Non-zero if privileged, 0 otherwise.
 */
extern int mbuf_is_traffic_class_privileged(mbuf_t mbuf);

#ifdef KERNEL_PRIVATE

/*!
 *       @function mbuf_get_traffic_class_max_count
 *       @discussion Returns the maximum number of mbuf traffic class types
 *       @result The total count of mbuf traffic classes
 */
extern u_int32_t mbuf_get_traffic_class_max_count(void);

/*!
 *       @function mbuf_get_traffic_class_index
 *       @discussion Returns the zero-based index of an mbuf traffic class value
 *       @param tc The traffic class
 *       @param index Pointer to the index value
 *       @result 0 on success, EINVAL if bad parameter is passed
 */
extern errno_t mbuf_get_traffic_class_index(mbuf_traffic_class_t tc,
    u_int32_t *index);

/*!
 *       @enum mbuf_svc_class_t
 *       @abstract Service class of a packet
 *       @discussion Property that represents the category of service
 *               of a packet. This information may be used by the driver
 *               and at the link level.
 *       @constant MBUF_SC_BK_SYS "Background System-Initiated", high delay
 *               tolerant, high loss tolerant, elastic flow, variable size &
 *               long-lived.
 *       @constant MBUF_SC_BK "Background", user-initiated, high delay tolerant,
 *               high loss tolerant, elastic flow, variable size.  This level
 *               corresponds to WMM access class "BG", or MBUF_TC_BK.
 *       @constant MBUF_SC_BE "Best Effort", unclassified/standard.  This is
 *               the default service class; pretty much a mix of everything.
 *               This level corresponds to WMM access class "BE" or MBUF_TC_BE.
 *       @constant MBUF_SC_RD
 *               "Responsive Data", a notch higher than "Best Effort", medium
 *               delay tolerant, medium loss tolerant, elastic flow, bursty,
 *               long-lived.
 *       @constant MBUF_SC_OAM "Operations, Administration, and Management",
 *               medium delay tolerant, low-medium loss tolerant, elastic &
 *               inelastic flows, variable size.
 *       @constant MBUF_SC_AV "Multimedia Audio/Video Streaming", medium delay
 *               tolerant, low-medium loss tolerant, elastic flow, constant
 *               packet interval, variable rate & size.
 *       @constant MBUF_SC_RV "Responsive Multimedia Audio/Video", low delay
 *               tolerant, low-medium loss tolerant, elastic flow, variable
 *               packet interval, rate and size.
 *       @constant MBUF_SC_VI "Interactive Video", low delay tolerant, low-
 *               medium loss tolerant, elastic flow, constant packet interval,
 *               variable rate & size.  This level corresponds to WMM access
 *               class "VI" or MBUF_TC_VI.
 *       @constant MBUF_SC_SIG "Signaling", low delay tolerant, low loss
 *               tolerant, inelastic flow, jitter tolerant, rate is bursty but
 *               short, variable size. e.g. SIP.  This level corresponds to WMM
 *               access class "VI" or MBUF_TC_VI.
 *       @constant MBUF_SC_VO "Interactive Voice", low delay tolerant, low loss
 *               tolerant, inelastic flow, constant packet rate, somewhat fixed
 *               size.  This level corresponds to WMM access class "VO" or
 *               MBUF_TC_VO.
 *       @constant MBUF_SC_CTL "Network Control", low delay tolerant, low loss
 *               tolerant, inelastic flow, rate is short & burst, variable size.
 */
typedef enum {
#ifdef XNU_KERNEL_PRIVATE
	MBUF_SC_UNSPEC          = -1,           /* Internal: not specified */
#endif
	MBUF_SC_BK_SYS          = 0x00080090,   /* lowest class */
	MBUF_SC_BK              = 0x00100080,

	MBUF_SC_BE              = 0x00000000,
	MBUF_SC_RD              = 0x00180010,
	MBUF_SC_OAM             = 0x00200020,

	MBUF_SC_AV              = 0x00280120,
	MBUF_SC_RV              = 0x00300110,
	MBUF_SC_VI              = 0x00380100,
	MBUF_SC_SIG             = 0x00380130,

	MBUF_SC_VO              = 0x00400180,
	MBUF_SC_CTL             = 0x00480190,   /* highest class */
} mbuf_svc_class_t;

/*!
 *       @function mbuf_get_service_class_max_count
 *       @discussion Returns the maximum number of mbuf service class types.
 *       @result The total count of mbuf service classes.
 */
extern u_int32_t mbuf_get_service_class_max_count(void);

/*!
 *       @function mbuf_get_service_class_index
 *       @discussion Returns the zero-based index of an mbuf service class value
 *       @param sc The service class
 *       @param index Pointer to the index value
 *       @result 0 on success, EINVAL if bad parameter is passed
 */
extern errno_t mbuf_get_service_class_index(mbuf_svc_class_t sc,
    u_int32_t *index);

/*!
 *       @function mbuf_get_service_class
 *       @discussion Get the service class of an mbuf packet
 *       @param mbuf The mbuf to get the service class of.
 *       @result The service class
 */
extern mbuf_svc_class_t mbuf_get_service_class(mbuf_t mbuf);

/*!
 *       @function mbuf_set_servicec_class
 *       @discussion Set the service class of an mbuf packet.
 *       @param mbuf The mbuf to set the service class on.
 *       @param sc The service class
 *       @result 0 on success, EINVAL if bad parameter is passed
 */
extern errno_t mbuf_set_service_class(mbuf_t mbuf, mbuf_svc_class_t sc);

/*!
 *       @function mbuf_is_service_class_privileged
 *       @discussion Returns the privileged status of the service class
 *               of the packet specified by the mbuf.
 *       @param mbuf The mbuf to retrieve the status from.
 *       @result Non-zero if privileged, 0 otherwise.
 */
extern int mbuf_is_service_class_privileged(mbuf_t mbuf);

/*!
 *       @enum mbuf_pkthdr_aux_flags_t
 *       @abstract Constants defining mbuf auxiliary flags.  Only the flags
 *               listed below can be retrieved.
 *       @constant MBUF_PKTAUXF_INET_RESOLVE_RTR Indicates this is an ARP
 *               request packet, whose target is the address of the default
 *               IPv4 router.
 *       @constant MBUF_PKTAUXF_INET6_RESOLVE_RTR Indicates this is an ICMPv6
 *               Neighbor Solicitation packet, whose target is the address of
 *               the default IPv6 router.
 */
enum {
	MBUF_PKTAUXF_INET_RESOLVE_RTR   = 0x0004,
	MBUF_PKTAUXF_INET6_RESOLVE_RTR  = 0x0008,
};
typedef u_int32_t mbuf_pkthdr_aux_flags_t;

/*!
 *       @function mbuf_pkthdr_aux_flags
 *       @discussion Returns the auxiliary flags of a packet.
 *       @param mbuf The mbuf containing the packet header.
 *       @param paux_flags Pointer to mbuf_pkthdr_aux_flags_t variable.
 *       @result 0 upon success otherwise the errno error.
 */
extern errno_t mbuf_pkthdr_aux_flags(mbuf_t mbuf,
    mbuf_pkthdr_aux_flags_t *paux_flags);

/*!
 *       @function mbuf_get_driver_scratch
 *       @discussion Returns a pointer to a driver specific area in the mbuf
 *       @param m The mbuf whose driver scratch space is to be returned
 *       @param area A pointer to a location to store the address of the
 *               driver scratch space.  This value is guaranteed to be 32-bit
 *               aligned.
 *       @param area_ln A pointer to a location to store the total length of
 *               the memory location.
 */
extern errno_t mbuf_get_driver_scratch(mbuf_t m, u_int8_t **area,
    size_t *area_ln);

/*!
 *       @function mbuf_get_unsent_data_bytes
 *       @discussion Returns the amount of data that is waiting to be sent
 *               on this interface. This is a private SPI used by cellular
 *               interface as an indication of future activity on that
 *               interface.
 *       @param m The mbuf containing the packet header
 *       @param unsent_data A pointer to an integer where the value of
 *               unsent data will be set.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_unsent_data_bytes(const mbuf_t m,
    u_int32_t *unsent_data);

typedef struct {
	int32_t buf_interface; /* data to send at interface */
	int32_t buf_sndbuf; /* data to send at socket buffer */
} mbuf_buffer_status_t;

/*!
 *       @function mbuf_get_buffer_status
 *       @discussion Returns the amount of data that is waiting to be sent
 *               on this interface. This is a private SPI used by cellular
 *               interface as an indication of future activity on that
 *               interface.
 *       @param m The mbuf containing the packet header
 *       @param buf_status A pointer to the structure where the value of
 *               unsent data will be set.
 *       @result 0 upon success. If any of the arguments is NULL or if the
 *               mbuf packet header does not have valid data bytes,
 *               EINVAL will be returned
 */
extern errno_t mbuf_get_buffer_status(const mbuf_t m,
    mbuf_buffer_status_t *buf_status);

/*!
 *       @function mbuf_pkt_new_flow
 *       @discussion This function is used to check if the packet is from a
 *               new flow that can be treated with higher priority. This is
 *               a private SPI.
 *       @param m The mbuf containing the packet header
 *       @param retval A pointer to an integer used as an out argument. The
 *               value is set to 1 if the packet is from a new flow,
 *               otherwise it is set to 0.
 *       @result	0 upon success otherwise the errno error. If any of the
 *               arguments is NULL or if the mbuf does not have valid packet
 *               header, the error code will be EINVAL
 */
extern errno_t mbuf_pkt_new_flow(const mbuf_t m, u_int32_t *retval);

/*!
 *       @function mbuf_last_pkt
 *       @discussion This function is used to check if the packet is the
 *               last one sent on a TCP socket. This is an advisory
 *               for the underlying layers.
 *       @param m The mbuf containing the packet header
 *       @param retval A pointer to an integer whose value will be set to
 *               1 if the packet is the last packet, otherwise it will
 *               be set to 0.
 *       @result 0 upon success otherwise the errno error. If any of the
 *               arguments is NULL or if the mbuf does not have valid
 *               packet header, the error code will be EINVAL
 */
extern errno_t mbuf_last_pkt(const mbuf_t m, u_int32_t *retval);

#endif /* KERNEL_PRIVATE */

#ifdef XNU_KERNEL_PRIVATE
/*!
 *       @function mbuf_pkt_list_len
 *       @discussion Retrieves the length of the list of mbuf packets.
 *       @param mbuf The mbuf.
 *       @result The length of the mbuf packet list.
 */
extern size_t mbuf_pkt_list_len(const mbuf_t mbuf);

/*!
 *       @function mbuf_pkt_list_maxlen
 *       @discussion Retrieves the maximum length of data that may be stored
 *               in the list of mbuf packet. This value assumes that the data pointer
 *               was set to the start of the possible range for that pointer
 *               for each mbuf in the packet chain
 *       @param mbuf The mbuf.
 *       @result The maximum length of data for this mbuf.
 */
extern size_t mbuf_pkt_list_maxlen(const mbuf_t mbuf);
#endif /* XNU_KERNEL_PRIVATE */

#ifdef KERNEL_PRIVATE
/*!
 *       @function mbuf_get_timestamp
 *       @discussion Retrieves the timestamp of the packet.
 *       @param mbuf The mbuf representing the packet.
 *       @param ts A pointer where the value of the timestamp will be copied
 *               to.
 *       @param valid A pointer to a boolean value that indicate if the
 *               timestamp is valid (i.e. the packet timestamp has been set).
 *               If "false" the value of "ts" is undetermined.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_timestamp(mbuf_t mbuf, u_int64_t *ts, boolean_t *valid);

/*!
 *       @function mbuf_set_timestamp
 *       @discussion Set the timestamp of the packet.
 *       @param mbuf The mbuf representing the packet.
 *       @param ts The value of the timestamp to be stored in the mbuf packet
 *               header
 *       @param valid A boolean value that indicate if the timestamp is valid.
 *               Passing false clears any previous timestamp value.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_set_timestamp(mbuf_t mbuf, u_int64_t ts, boolean_t valid);

/*!
 *       @typedef mbuf_tx_compl_func
 *       @discussion This callback is used to indicate when a driver has
 *               transmitted a packet.
 *       @param pktid The packet indentifier that was returned by
 *               mbuf_set_timestamp_requested()
 *       @param ifp The outgoing interface or NULL if the packet was dropped
 *               before reaching the driver
 *       @param ts The timestamp in nanoseconds when the packet was transmitted
 *       @param tx_compl_arg An argument set by the driver
 *       @param tx_compl_data Additional data set by the driver
 *       @param tx_compl_val The transmission status is expected to be an
 *               IOReturn value -- see <IOKit/IOReturn.h>
 */

typedef void (*mbuf_tx_compl_func)(uintptr_t pktid, ifnet_t ifp, u_int64_t ts,
    uintptr_t tx_compl_arg, uintptr_t tx_compl_data, kern_return_t tx_compl_val);

/*!
 *       @function mbuf_register_tx_compl_callback
 *       @discussion Register a transmit completion callback function. The
 *               callback function must be unregistered before the calling
 *               module unloads.
 *       @param callback The completion callback function to register
 *       @result 0 upon success otherwise the errno error. ENOSPC is returned
 *               if too many callbacks are registered. EINVAL is returned when
 *               the function pointer is invalid. EEXIST is returned when
 *               the function pointer is already registered.
 */
extern errno_t mbuf_register_tx_compl_callback(
	mbuf_tx_compl_func callback);

/*!
 *       @function mbuf_unregister_tx_compl_callback
 *       @discussion Unregister a transmit completion callback function. The
 *               callback function must be unregistered before the calling
 *               module unloads.
 *       @param callback The completion callback function to unregister
 *       @result 0 upon success otherwise the errno error. EINVAL is returned
 *               when the function pointer is invalid. ENOENT is returned when
 *               the function pointer is not registered.
 */
extern errno_t mbuf_unregister_tx_compl_callback(
	mbuf_tx_compl_func callback);

/*!
 *       @function mbuf_get_timestamp_requested
 *       @discussion Tell if the packet timestamp needs to be set. This is meant
 *               to be used by a driver on egress packets.
 *       @param mbuf The mbuf representing the packet.
 *       @param requested A pointer to a boolean value that indicate if the
 *               timestamp was requested to be set.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_timestamp_requested(mbuf_t mbuf, boolean_t *requested);

/*!
 *       @function mbuf_set_timestamp_requested
 *       @discussion Indicate the callback is expected to be called with the
 *               transmission complete timestamp. This is meant to be used
 *               on egress packet by the driver.
 *       @param mbuf The mbuf representing the packet.
 *       @param callback A previously registered completion callback function.
 *       @param pktid An output parameter with an opaque value that can be used
 *               to identify the packet.
 *       @result 0 upon success otherwise the errno error. EINVAL is retuned
 *               if the mbuf is not a valid packet or if one of the parameter
 *               is NULL. ENOENT if the callback is not registred.
 */
extern errno_t mbuf_set_timestamp_requested(mbuf_t mbuf,
    uintptr_t *pktid, mbuf_tx_compl_func callback);

/*!
 *       @function mbuf_get_status
 *       @discussion Retrieves the packet completion status.
 *       @param mbuf The mbuf representing the packet.
 *       @param status A pointer where the value of the completion status will
 *               be copied to.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_status(mbuf_t mbuf, kern_return_t *status);

/*!
 *       @function mbuf_set_status
 *       @discussion Store the packet completion status in the mbuf packet
 *               header.
 *       @param mbuf The mbuf representing the packet.
 *       @param status The value of the completion status.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_set_status(mbuf_t mbuf, kern_return_t status);

/*!
 *       @function mbuf_get_tx_compl_data
 *       @discussion Retrieves the packet completion status.
 *       @param m The mbuf representing the packet.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_tx_compl_data(mbuf_t m, uintptr_t *arg,
    uintptr_t *data);

/*!
 *       @function mbuf_set_tx_compl_data
 *       @discussion Retrieves the packet completion status.
 *       @param m The mbuf representing the packet.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_set_tx_compl_data(mbuf_t m, uintptr_t arg,
    uintptr_t data);

/*!
 *       @function mbuf_get_flowid
 *       @discussion Retrieve the flow ID of the packet .
 *       @param mbuf The mbuf representing the packet.
 *       @param flowid The flow ID of the packet.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_flowid(mbuf_t mbuf, u_int16_t *flowid);

/*!
 *       @function mbuf_set_flowid
 *       @discussion Set the flow ID of the packet .
 *       @param mbuf The mbuf representing the packet.
 *       @param flowid The flow ID to be set.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_set_flowid(mbuf_t mbuf, u_int16_t flowid);

/*!
 *       @function mbuf_get_keepalive_flag
 *       @discussion Tell if it's a keep alive packet.
 *       @param mbuf The mbuf representing the packet.
 *       @param is_keepalive A pointer that returns the truth value.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_get_keepalive_flag(mbuf_t mbuf, boolean_t *is_keepalive);

/*!
 *       @function mbuf_set_keepalive_flag
 *       @discussion Set or clear the packet keep alive flag.
 *       @param mbuf The mbuf representing the packet.
 *       @param is_keepalive The boolean value.
 *       @result 0 upon success otherwise the errno error. If the mbuf
 *               packet header does not have valid data bytes, the error
 *               code will be EINVAL
 */
extern errno_t mbuf_set_keepalive_flag(mbuf_t mbuf, boolean_t is_keepalive);

#endif /* KERNEL_PRIVATE */

/* IF_QUEUE interaction */

#define IF_ENQUEUE_MBUF(ifq, m) {                                       \
	mbuf_setnextpkt((m), 0);                                        \
	if ((ifq)->ifq_tail == 0)                                       \
	        (ifq)->ifq_head = (m);                                  \
	else                                                            \
	        mbuf_setnextpkt((mbuf_t)(ifq)->ifq_tail, (m));          \
	(ifq)->ifq_tail = (m);                                          \
	(ifq)->ifq_len++;                                               \
}

#define IF_PREPEND_MBUF(ifq, m) {                                       \
	mbuf_setnextpkt((m), (ifq)->ifq_head);                          \
	if ((ifq)->ifq_tail == 0)                                       \
	        (ifq)->ifq_tail = (m);                                  \
	(ifq)->ifq_head = (m);                                          \
	(ifq)->ifq_len++;                                               \
}

#define IF_DEQUEUE_MBUF(ifq, m) {                                       \
	(m) = (ifq)->ifq_head;                                          \
	if (m) {                                                        \
	        if (((ifq)->ifq_head = mbuf_nextpkt((m))) == 0)         \
	                (ifq)->ifq_tail = 0;                            \
	        mbuf_setnextpkt((m), 0);                                \
	        (ifq)->ifq_len--;                                       \
	}                                                               \
}

__END_DECLS
#endif /* __KPI_MBUF__ */
