source: vbox/trunk/src/VBox/Devices/Network/SrvIntNetR0.cpp@ 10734

/* $Id: SrvIntNetR0.cpp 10734 2008-07-17 23:04:13Z vboxsync $ */
/** @file
 * Internal networking - The ring 0 service.
 */

/*
 * Copyright (C) 2006-2007 Sun Microsystems, Inc.
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 USA or visit http://www.sun.com if you need
 * additional information or have any questions.
 */


/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#define LOG_GROUP LOG_GROUP_SRV_INTNET
#include <VBox/intnet.h>
#include <VBox/sup.h>
#include <VBox/pdm.h>
#include <VBox/log.h>
#include <iprt/asm.h>
#include <iprt/alloc.h>
#include <iprt/semaphore.h>
#include <iprt/spinlock.h>
#include <iprt/thread.h>
#include <iprt/assert.h>
#include <iprt/string.h>
#include <iprt/time.h>


/*******************************************************************************
*   Structures and Typedefs                                                    *
*******************************************************************************/
/**
 * A network interface.
 *
 * Unless explicitly stated, all members are protect by the network semaphore.
 */
typedef struct INTNETIF
{
    /** Pointer to the next interface.
     * This is protected by the INTNET::FastMutex. */
    struct INTNETIF        *pNext;
    /** The current MAC address for the interface. */
    PDMMAC                  Mac;
    /** Set if the INTNET::Mac member is valid. */
    bool                    fMacSet;
    /** Set if the interface is in promiscuous mode.
     * In promiscuous mode the interface will receive all packages except the one it's sending. */
    bool                    fPromiscuous;
    /** Whether the interface is active or not. */
    bool                    fActive;
    /** Number of yields done to try make the interface read pending data.
     * We will stop yeilding when this reaches a threshold assuming that the VM is paused or
     * that it simply isn't worth all the delay. It is cleared when a successful send has been done.
     */
    uint32_t                cYields;
    /** Pointer to the current exchange buffer (ring-0). */
    PINTNETBUF              pIntBuf;
    /** Pointer to ring-3 mapping of the current exchange buffer. */
    R3PTRTYPE(PINTNETBUF)   pIntBufR3;
    /** Pointer to the default exchange buffer for the interface. */
    PINTNETBUF              pIntBufDefault;
    /** Pointer to ring-3 mapping of the default exchange buffer. */
    R3PTRTYPE(PINTNETBUF)   pIntBufDefaultR3;
    /** Event semaphore which a receiver thread will sleep on while waiting for data to arrive. */
    RTSEMEVENT              Event;
    /** Number of threads sleeping on the Event semaphore. */
    uint32_t                cSleepers;
    /** The interface handle.
     * When this is INTNET_HANDLE_INVALID a sleeper which is waking up
     * should return with the appropriate error condition. */
    INTNETIFHANDLE          hIf;
    /** Pointer to the network this interface is connected to.
     * This is protected by the INTNET::FastMutex. */
    struct INTNETNETWORK   *pNetwork;
    /** The session this interface is associated with. */
    PSUPDRVSESSION          pSession;
    /** The SUPR0 object id. */
    void                   *pvObj;
} INTNETIF;
/** Pointer to an internal network interface. */
typedef INTNETIF *PINTNETIF;


/**
 * A trunk interface.
 */
typedef struct INTNETTRUNKIF
{
    /** The port interface we present to the component. */
    INTNETTRUNKSWPORT       SwitchPort;
    /** The port interface we get from the component. */
    PINTNETTRUNKIFPORT      pIfPort;
    /** The trunk mutex that serializes all calls <b>to</b> the component. */
    RTSEMFASTMUTEX          FastMutex;
    /** Pointer to the network we're connect to.
     * This may be NULL if we're orphaned? */
    struct INTNETNETWORK   *pNetwork;
    /** Whether to supply physical addresses with the outbound SGs. */
    bool volatile           fPhysSG;
    /** Set if the 'wire' is in promiscuous mode.
     * The state of the 'host' is queried each time. */
    bool                    fPromiscuousWire;
} INTNETTRUNKIF;
/** Pointer to a trunk interface. */
typedef INTNETTRUNKIF *PINTNETTRUNKIF;

/** Converts a pointer to INTNETTRUNKIF::SwitchPort to a PINTNETTRUNKIF. */
#define INTNET_SWITCHPORT_2_TRUNKIF(pSwitchPort) ((PINTNETTRUNKIF)(pSwitchPort))


/**
 * Internal representation of a network.
 */
typedef struct INTNETNETWORK
{
    /** The Next network in the chain.
     * This is protected by the INTNET::FastMutex. */
    struct INTNETNETWORK   *pNext;
    /** List of interfaces connected to the network.
     * This is protected by the INTNET::FastMutex. */
    PINTNETIF               pIFs;
    /** Pointer to the trunk interface.
     * Can be NULL if there is no trunk connection. */
    PINTNETTRUNKIF          pTrunkIF;
    /** The network mutex.
     * It protects everything dealing with this network. */
    RTSEMFASTMUTEX          FastMutex;
    /** Pointer to the instance data. */
    struct INTNET          *pIntNet;
    /** The SUPR0 object id. */
    void                   *pvObj;
    /** Network creation flags (INTNET_OPEN_FLAGS_*). */
    uint32_t                fFlags;
    /** The number of active interfaces (excluding the trunk). */
    uint32_t                cActiveIFs;
    /** The length of the network name. */
    uint8_t                 cchName;
    /** The network name. */
    char                    szName[INTNET_MAX_NETWORK_NAME];
    /** The trunk type. */
    INTNETTRUNKTYPE         enmTrunkType;
    /** The trunk name. */
    char                    szTrunk[INTNET_MAX_TRUNK_NAME];
} INTNETNETWORK;
/** Pointer to an internal network. */
typedef INTNETNETWORK *PINTNETNETWORK;


/**
 * Handle table entry.
 * @todo move to IPRT.
 */
typedef union INTNETHTE
{
    /** Pointer to the object we're a handle for. */
    PINTNETIF               pIF;
    /** Index to the next free entry. */
    uintptr_t               iNext;
} INTNETHTE;
/** Pointer to a handle table entry. */
typedef INTNETHTE *PINTNETHTE;


/**
 * Handle table.
 * @todo move to IPRT (RTHandleTableCreate/Destroy/Add/Delete/Lookup).
 */
typedef struct INTNETHT
{
    /** Spinlock protecting all access. */
    RTSPINLOCK              Spinlock;
    /** Pointer to the handle table. */
    PINTNETHTE              paEntries;
    /** The number of allocated handles. */
    uint32_t                cAllocated;
    /** The index of the first free handle entry.
     * UINT32_MAX means empty list. */
    uint32_t volatile       iHead;
    /** The index of the last free handle entry.
     * UINT32_MAX means empty list. */
    uint32_t volatile       iTail;
} INTNETHT;
/** Pointer to a handle table. */
typedef INTNETHT *PINTNETHT;


/**
 * Internal networking instance.
 */
typedef struct INTNET
{
    /** Mutex protecting the network creation, opening and destruction.
     * (This means all operations affecting the pNetworks list.) */
    RTSEMFASTMUTEX          FastMutex;
    /** List of networks. Protected by INTNET::Spinlock. */
    PINTNETNETWORK volatile pNetworks;
    /** Handle table for the interfaces. */
    INTNETHT                IfHandles;
} INTNET;


/*******************************************************************************
*   Internal Functions                                                         *
*******************************************************************************/
static PINTNETTRUNKIF intnetR0TrunkIfRetain(PINTNETTRUNKIF pThis);
static void intnetR0TrunkIfRelease(PINTNETTRUNKIF pThis);
static bool intnetR0TrunkIfOutLock(PINTNETTRUNKIF pThis);
static void intnetR0TrunkIfOutUnlock(PINTNETTRUNKIF pThis);



/**
 * Validates and translates an interface handle to a interface pointer.
 *
 * The caller already owns the spinlock, which means this is
 * for internal use only.
 *
 * @returns Pointer to interface.
 * @returns NULL if the handle is invalid.
 * @param   pHT         Pointer to the handle table.
 * @param   hIF         The interface handle to validate and translate.
 *
 * @internal
 */
DECLINLINE(PINTNETIF) intnetR0Handle2IFPtrLocked(PINTNETHT pHT, INTNETIFHANDLE hIF)
{
    if (RT_LIKELY((hIF & INTNET_HANDLE_MAGIC) == INTNET_HANDLE_MAGIC))
    {
        const uint32_t i = hIF & INTNET_HANDLE_INDEX_MASK;
        if (RT_LIKELY(   i < pHT->cAllocated
                      && pHT->paEntries[i].iNext >= INTNET_HANDLE_MAX
                      && pHT->paEntries[i].iNext != UINT32_MAX))
            return pHT->paEntries[i].pIF;
    }
    return NULL;
}


/**
 * Validates and translates an interface handle to a interface pointer.
 *
 * @returns Pointer to interface.
 * @returns NULL if the handle is invalid.
 * @param   pHT         Pointer to the handle table.
 * @param   hIF         The interface handle to validate and translate.
 */
DECLINLINE(PINTNETIF) intnetR0Handle2IFPtr(PINTNETHT pHT, INTNETIFHANDLE hIF)
{
    AssertPtr(pHT);
    RTSPINLOCKTMP   Tmp = RTSPINLOCKTMP_INITIALIZER;
    RTSpinlockAcquire(pHT->Spinlock, &Tmp);
    PINTNETIF pIF = intnetR0Handle2IFPtrLocked(pHT, hIF);
    RTSpinlockRelease(pHT->Spinlock, &Tmp);

    return pIF;
}


/**
 * Allocates a handle for an interface.
 *
 * @returns Handle on success.
 * @returns Invalid handle on failure.
 * @param   pIntNet     Pointer to the instance data.
 * @param   pIF         The interface which we're allocating a handle for.
 */
static INTNETIFHANDLE intnetR0HandleAllocate(PINTNET pIntNet, PINTNETIF pIF)
{
    Assert(pIF);
    Assert(pIntNet);
    unsigned    cTries = 10;
    PINTNETHT   pHT = &pIntNet->IfHandles;
    PINTNETHTE  paNew = NULL;

    RTSPINLOCKTMP Tmp = RTSPINLOCKTMP_INITIALIZER;
    RTSpinlockAcquire(pHT->Spinlock, &Tmp);
    for (;;)
    {
        /*
         * Check the free list.
         */
        uint32_t i = pHT->iHead;
        if (i != UINT32_MAX)
        {
            pHT->iHead = pHT->paEntries[i].iNext;
            if (pHT->iHead == UINT32_MAX)
                pHT->iTail = UINT32_MAX;

            pHT->paEntries[i].pIF = pIF;
            RTSpinlockRelease(pHT->Spinlock, &Tmp);
            if (paNew)
                RTMemFree(paNew);
            return i | INTNET_HANDLE_MAGIC;
        }

        /*
         * Leave the spinlock and allocate a new array.
         */
        const unsigned cNew = pHT->cAllocated + 128;
        RTSpinlockRelease(pHT->Spinlock, &Tmp);
        if (--cTries <= 0)
        {
            AssertMsgFailed(("Giving up!\n"));
            break;
        }
        paNew = (PINTNETHTE)RTMemAlloc(sizeof(*paNew) * cNew);
        if (!paNew)
            break;

        /*
         * Acquire the spinlock and check if someone raced us.
         */
        RTSpinlockAcquire(pHT->Spinlock, &Tmp);
        if (pHT->cAllocated < cNew)
        {
            /* copy the current table. */
            memcpy(paNew, pHT->paEntries, pHT->cAllocated * sizeof(*paNew));

            /* link the new entries into the free chain. */
            i = pHT->cAllocated;
            uint32_t iTail = pHT->iTail;
            if (iTail == UINT32_MAX)
                pHT->iHead = iTail = i++;
            while (i < cNew)
            {
                paNew[iTail].iNext = i;
                iTail = i++;
            }
            paNew[iTail].iNext = UINT32_MAX;
            pHT->iTail = iTail;

            /* update the handle table. */
            pHT->cAllocated = cNew;
            paNew = (PINTNETHTE)ASMAtomicXchgPtr((void * volatile *)&pHT->paEntries, paNew);
        }
    }

    if (paNew)
        RTMemFree(paNew);
    return INTNET_HANDLE_INVALID;
}


/**
 * Validates and frees a handle.
 *
 * @returns Pointer to interface.
 * @returns NULL if the handle is invalid.
 * @param   pHT         Pointer to the handle table.
 * @param   h           The handle we're freeing.
 */
static PINTNETIF intnetR0HandleFree(PINTNETHT pHT, INTNETIFHANDLE h)
{
    RTSPINLOCKTMP   Tmp = RTSPINLOCKTMP_INITIALIZER;
    RTSpinlockAcquire(pHT->Spinlock, &Tmp);

    /*
     * Validate and get it, then insert the handle table entry
     * at the end of the free list.
     */
    PINTNETIF pIF = intnetR0Handle2IFPtrLocked(pHT, h);
    if (pIF)
    {
        const uint32_t i = h & INTNET_HANDLE_INDEX_MASK;
        pHT->paEntries[i].iNext = UINT32_MAX;
        const uint32_t iTail = pHT->iTail;
        if (iTail != UINT32_MAX)
            pHT->paEntries[iTail].iNext = i;
        else
            pHT->iHead = i;
        pHT->iTail = i;
    }

    RTSpinlockRelease(pHT->Spinlock, &Tmp);

    AssertMsg(pIF, ("%d >= %d\n", h & INTNET_HANDLE_INDEX_MASK, pHT->cAllocated));
    return pIF;
}


/**
 * Initializes a scatter / gather buffer from a simple linear buffer.
 *
 * @returns Pointer to the start of the frame.
 * @param   pSG         Pointer to the scatter / gather structure.
 *                      (The pvOwnerData, fFlags, cUsers, and cSegsAlloc members are left untouched.)
 * @param   pvFrame     Pointer to the frame
 * @param   cbFrame     The size of the frame.
 */
DECLINLINE(void) intnetR0SgInitTemp(PINTNETSG pSG, void *pvFrame, uint32_t cbFrame)
{
    pSG->pvOwnerData = NULL;
    pSG->pvUserData = NULL;
    pSG->pvUserData2 = NULL;
    pSG->cbTotal = cbFrame;
    pSG->cUsers = 1;
    pSG->fFlags = INTNETSG_FLAGS_TEMP;
    pSG->cSegsAlloc = 1;
    pSG->cSegsUsed = 1;
    pSG->aSegs[0].Phys = NIL_RTHCPHYS;
    pSG->aSegs[0].pv = pvFrame;
    pSG->aSegs[0].cb = cbFrame;
}


/**
 * Initializes a scatter / gather buffer from a internal networking packet.
 *
 * @returns Pointer to the start of the frame.
 * @param   pSG         Pointer to the scatter / gather structure.
 *                      (The pvOwnerData, fFlags, cUsers, and cSegsAlloc members are left untouched.)
 * @param   pHdr        Pointer to the packet header.
 * @param   pBuf        The buffer the header is within. Only used in strict builds.
 */
DECLINLINE(void) intnetR0SgInitFromPkt(PINTNETSG pSG, PCINTNETHDR pPktHdr, PCINTNETBUF pBuf)
{
    pSG->cSegsUsed = 1;
    pSG->cbTotal = pSG->aSegs[0].cb = pPktHdr->cbFrame;
    pSG->aSegs[0].pv = INTNETHdrGetFramePtr(pPktHdr, pBuf);
    pSG->aSegs[0].Phys = NIL_RTHCPHYS;
}


#ifdef IN_INTNET_TESTCASE
/**
 * Reads the next frame in the buffer.
 * The caller is responsible for ensuring that there is a valid frame in the buffer.
 *
 * @returns Size of the frame in bytes.
 * @param   pBuf        The buffer.
 * @param   pRingBuff   The ring buffer to read from.
 * @param   pvFrame     Where to put the frame. The caller is responsible for
 *                      ensuring that there is sufficient space for the frame.
 */
static unsigned intnetR0RingReadFrame(PINTNETBUF pBuf, PINTNETRINGBUF pRingBuf, void *pvFrame)
{
    Assert(pRingBuf->offRead < pBuf->cbBuf);
    Assert(pRingBuf->offRead >= pRingBuf->offStart);
    Assert(pRingBuf->offRead < pRingBuf->offEnd);
    uint32_t    offRead   = pRingBuf->offRead;
    PINTNETHDR  pHdr      = (PINTNETHDR)((uint8_t *)pBuf + offRead);
    const void *pvFrameIn = INTNETHdrGetFramePtr(pHdr, pBuf);
    unsigned    cb        = pHdr->cbFrame;
    memcpy(pvFrame, pvFrameIn, cb);

    /* skip the frame */
    offRead += pHdr->offFrame + cb;
    offRead = RT_ALIGN_32(offRead, sizeof(INTNETHDR));
    Assert(offRead <= pRingBuf->offEnd && offRead >= pRingBuf->offStart);
    if (offRead >= pRingBuf->offEnd)
        offRead = pRingBuf->offStart;
    ASMAtomicXchgU32(&pRingBuf->offRead, offRead);
    return cb;
}
#endif /* IN_INTNET_TESTCASE */


/**
 * Reads an entire SG into a fittingly size buffer.
 *
 * @param   pSG         The SG list to read.
 * @param   pvBuf       The buffer to read into (at least pSG->cbTotal in size).
 */
DECLINLINE(void) intnetR0SgRead(PCINTNETSG pSG, void *pvBuf)
{
    if (pSG->cSegsUsed == 1)
    {
        Assert(pSG->cbTotal == pSG->aSegs[0].cb);
        memcpy(pvBuf, pSG->aSegs[0].pv, pSG->cbTotal);
    }
    else
    {
        uint8_t       *pbDst = (uint8_t *)pvBuf;
        unsigned const cSegs = pSG->cSegsUsed; Assert(cSegs == pSG->cSegsUsed);
        for (unsigned iSeg = 0; iSeg < cSegs; iSeg++)
        {
            uint32_t cbSeg = pSG->aSegs[iSeg].cb;
            Assert(cbSeg <= pSG->cbTotal && (uintptr_t)(pbDst - (uint8_t *)pvBuf) + cbSeg <= pSG->cbTotal);
            memcpy(pbDst, pSG->aSegs[iSeg].pv, cbSeg);
            pbDst += cbSeg;
        }
    }
}


/**
 * Writes a frame packet to the buffer.
 *
 * @returns VBox status code.
 * @param   pBuf        The buffer.
 * @param   pRingBuf    The ring buffer to read from.
 * @param   pSG         The gatter list.
 */
static int intnetR0RingWriteFrame(PINTNETBUF pBuf, PINTNETRINGBUF pRingBuf, PCINTNETSG pSG)
{
    /*
     * Validate input.
     */
    AssertPtr(pBuf);
    AssertPtr(pRingBuf);
    AssertPtr(pSG);
    Assert(pSG->cbTotal >= sizeof(PDMMAC) * 2);
    uint32_t offWrite = pRingBuf->offWrite;
    Assert(offWrite == RT_ALIGN_32(offWrite, sizeof(INTNETHDR)));
    uint32_t offRead = pRingBuf->offRead;
    Assert(offRead == RT_ALIGN_32(offRead, sizeof(INTNETHDR)));

    const uint32_t cb = RT_ALIGN_32(pSG->cbTotal, sizeof(INTNETHDR));
    if (offRead <= offWrite)
    {
        /*
         * Try fit it all before the end of the buffer.
         */
        if (pRingBuf->offEnd - offWrite >= cb + sizeof(INTNETHDR))
        {
            PINTNETHDR pHdr = (PINTNETHDR)((uint8_t *)pBuf + offWrite);
            pHdr->u16Type  = INTNETHDR_TYPE_FRAME;
            pHdr->cbFrame  = pSG->cbTotal;
            pHdr->offFrame = sizeof(INTNETHDR);

            intnetR0SgRead(pSG, pHdr + 1);

            offWrite += cb + sizeof(INTNETHDR);
            Assert(offWrite <= pRingBuf->offEnd && offWrite >= pRingBuf->offStart);
            if (offWrite >= pRingBuf->offEnd)
                offWrite = pRingBuf->offStart;
            Log2(("WriteFrame: offWrite: %#x -> %#x (1)\n", pRingBuf->offWrite, offWrite));
            ASMAtomicXchgU32(&pRingBuf->offWrite, offWrite);
            return VINF_SUCCESS;
        }

        /*
         * Try fit the frame at the start of the buffer.
         * (The header fits before the end of the buffer because of alignment.)
         */
        AssertMsg(pRingBuf->offEnd - offWrite >= sizeof(INTNETHDR), ("offEnd=%x offWrite=%x\n", pRingBuf->offEnd, offWrite));
        if (offRead - pRingBuf->offStart > cb) /* not >= ! */
        {
            PINTNETHDR  pHdr = (PINTNETHDR)((uint8_t *)pBuf + offWrite);
            void       *pvFrameOut = (PINTNETHDR)((uint8_t *)pBuf + pRingBuf->offStart);
            pHdr->u16Type  = INTNETHDR_TYPE_FRAME;
            pHdr->cbFrame  = pSG->cbTotal;
            pHdr->offFrame = (intptr_t)pvFrameOut - (intptr_t)pHdr;

            intnetR0SgRead(pSG, pvFrameOut);

            offWrite = pRingBuf->offStart + cb;
            ASMAtomicXchgU32(&pRingBuf->offWrite, offWrite);
            Log2(("WriteFrame: offWrite: %#x -> %#x (2)\n", pRingBuf->offWrite, offWrite));
            return VINF_SUCCESS;
        }
    }
    /*
     * The reader is ahead of the writer, try fit it into that space.
     */
    else if (offRead - offWrite > cb + sizeof(INTNETHDR)) /* not >= ! */
    {
        PINTNETHDR pHdr = (PINTNETHDR)((uint8_t *)pBuf + offWrite);
        pHdr->u16Type  = INTNETHDR_TYPE_FRAME;
        pHdr->cbFrame  = pSG->cbTotal;
        pHdr->offFrame = sizeof(INTNETHDR);

        intnetR0SgRead(pSG, pHdr + 1);

        offWrite += cb + sizeof(INTNETHDR);
        ASMAtomicXchgU32(&pRingBuf->offWrite, offWrite);
        Log2(("WriteFrame: offWrite: %#x -> %#x (3)\n", pRingBuf->offWrite, offWrite));
        return VINF_SUCCESS;
    }

    /* (it didn't fit) */
    /** @todo stats */
    return VERR_BUFFER_OVERFLOW;
}


/**
 * Ethernet header.
 */
#pragma pack(1)
typedef struct INTNETETHERHDR
{
    PDMMAC  MacDst;
    PDMMAC  MacSrc;
} INTNETETHERHDR;
#pragma pack()
typedef INTNETETHERHDR *PINTNETETHERHDR;
typedef INTNETETHERHDR const *PCINTNETETHERHDR;


/**
 * Sends a frame to a specific interface.
 *
 * @param   pIf         The interface.
 * @param   pSG         The gather buffer which data is being sent to the interface.
 */
static void intnetR0IfSend(PINTNETIF pIf, PINTNETSG pSG)
{
    LogFlow(("intnetR0IfSend: pIf=%p:{.hIf=%RX32}\n", pIf, pIf->hIf));
    int rc = intnetR0RingWriteFrame(pIf->pIntBuf, &pIf->pIntBuf->Recv, pSG);
    if (RT_SUCCESS(rc))
    {
        pIf->cYields = 0;
        STAM_REL_COUNTER_INC(&pIf->pIntBuf->cStatRecvs);
        STAM_REL_COUNTER_ADD(&pIf->pIntBuf->cbStatRecv, pSG->cbTotal);
        RTSemEventSignal(pIf->Event);
        return;
    }

/** @todo we'll have to drop this I'm afraid since it'll screw up the host networking otherwise... */
    /*
     * Retry a few times, yielding the CPU in between.
     * But don't let a unresponsive VM harm performance, so give up after a short while.
     */
    if (pIf->cYields < 100)
    {
        unsigned cYields = 10;
        do
        {
            RTSemEventSignal(pIf->Event);
            RTThreadYield();
            rc = intnetR0RingWriteFrame(pIf->pIntBuf, &pIf->pIntBuf->Recv, pSG);
            if (RT_SUCCESS(rc))
            {
                STAM_REL_COUNTER_INC(&pIf->pIntBuf->cStatYieldsOk);
                STAM_REL_COUNTER_INC(&pIf->pIntBuf->cStatRecvs);
                STAM_REL_COUNTER_ADD(&pIf->pIntBuf->cbStatRecv, pSG->cbTotal);
                RTSemEventSignal(pIf->Event);
                return;
            }
            pIf->cYields++;
        } while (--cYields > 0);
        STAM_REL_COUNTER_INC(&pIf->pIntBuf->cStatYieldsNok);
    }

    /* ok, the frame is lost. */
    STAM_REL_COUNTER_INC(&pIf->pIntBuf->cStatLost);
    RTSemEventSignal(pIf->Event);
}


/**
 * Sends a frame down the trunk.
 *
 * The caller must own the network mutex, might be abandond temporarily.
 * The fTrunkLock parameter indicates whether the trunk lock is held.
 *
 * @param   pThis           The trunk.
 * @param   pNetwork        The network the frame is being sent to.
 * @param   fDst            The destination flags.
 * @param   pSG             Pointer to the gather list.
 * @param   fTrunkLocked    Whether the caller owns the out-bound trunk lock.
 */
static void intnetR0TrunkIfSend(PINTNETTRUNKIF pThis, PINTNETNETWORK pNetwork, uint32_t fDst, PINTNETSG pSG, bool fTrunkLocked)
{
    /*
     * Quick sanity check.
     */
    AssertPtr(pThis);
    AssertPtr(pNetwork);
    AssertPtr(pSG);
    Assert(fDst);
    AssertReturnVoid(pThis->pIfPort);

    /*
     * Temporarily leave the network lock while transmitting the frame.
     *
     * Note that we're relying on the out-bound lock to serialize threads down
     * in INTNETR0IfSend. It's theoretically possible for there to be race now
     * because I didn't implement async SG handling yet. Which is why we currently
     * require the trunk to be locked, well, one of the reasons.
     */
    AssertReturnVoid(fTrunkLocked); /* to be removed. */

    int rc;
    if (    fTrunkLocked
        ||  intnetR0TrunkIfRetain(pThis))
    {
        rc = RTSemFastMutexRelease(pNetwork->FastMutex);
        AssertRC(rc);
        if (RT_SUCCESS(rc))
        {
            if (    fTrunkLocked
                ||  intnetR0TrunkIfOutLock(pThis))
            {
                rc = pThis->pIfPort->pfnXmit(pThis->pIfPort, pSG, fDst);

                if (!fTrunkLocked)
                    intnetR0TrunkIfOutUnlock(pThis);
            }
            else
            {
                AssertFailed();
                rc = VERR_SEM_DESTROYED;
            }

            int rc2 = RTSemFastMutexRequest(pNetwork->FastMutex);
            AssertRC(rc2);
        }

        if (!fTrunkLocked)
            intnetR0TrunkIfRelease(pThis);
    }
    else
    {
        AssertFailed();
        rc = VERR_SEM_DESTROYED;
    }

    /** @todo failure statistics? */
}


/**
 * Sends a broadcast frame.
 *
 * The caller must own the network mutex, might be abandond temporarily.
 * When pIfSender is not NULL, the caller must also own the trunk semaphore.
 *
 * @returns true if it's addressed to someone on the network, otherwise false.
 * @param   pNetwork        The network the frame is being sent to.
 * @param   pIfSender       The interface sending the frame. This is NULL if it's the trunk.
 * @param   fSrc            The source flags. This 0 if it's not from the trunk.
 * @param   pSG             Pointer to the gather list.
 * @param   fTrunkLocked    Whether the caller owns the out-bound trunk lock.
 */
static bool intnetR0NetworkSendBroadcast(PINTNETNETWORK pNetwork, PINTNETIF pIfSender, PINTNETSG pSG, bool fTrunkLocked)
{
    /*
     * This is a broadcast or multicast address. For the present we treat those
     * two as the same - investigating multicast is left for later.
     *
     * Write the packet to all the interfaces and signal them.
     */
    Log2(("Broadcast\n"));
    for (PINTNETIF pIf = pNetwork->pIFs; pIf; pIf = pIf->pNext)
        if (pIf != pIfSender)
            intnetR0IfSend(pIf, pSG);

    /*
     * Unless the trunk is the origin, broadcast it to both the wire
     * and the host as well.
     */
    PINTNETTRUNKIF pTrunkIf = pNetwork->pTrunkIF;
    if (    pIfSender
        &&  pTrunkIf)
        intnetR0TrunkIfSend(pTrunkIf, pNetwork, INTNETTRUNKDIR_HOST | INTNETTRUNKDIR_WIRE, pSG, fTrunkLocked);
    return false; /* broadcast frames are never dropped */
}


/**
 * Sends a multicast frame.
 *
 * The caller must own the network mutex, might be abandond temporarily.
 *
 * @returns true if it's addressed to someone on the network, otherwise false.
 * @param   pNetwork        The network the frame is being sent to.
 * @param   pIfSender       The interface sending the frame. This is NULL if it's the trunk.
 * @param   fSrc            The source flags. This 0 if it's not from the trunk.
 * @param   pSG             Pointer to the gather list.
 * @param   fTrunkLocked    Whether the caller owns the out-bound trunk lock.
 * @param   pEthHdr         Pointer to the ethernet header.
 */
static bool intnetR0NetworkSendMulticast(PINTNETNETWORK pNetwork, PINTNETIF pIfSender, uint32_t fSrc, PINTNETSG pSG, bool fTrunkLocked, PCINTNETETHERHDR pEthHdr)
{
    /** @todo implement multicast */
    return intnetR0NetworkSendBroadcast(pNetwork, pIfSender, pSG, fTrunkLocked);
}


/**
 * Sends a unicast frame.
 *
 * The caller must own the network mutex, might be abandond temporarily.
 *
 * @returns true if it's addressed to someone on the network, otherwise false.
 * @param   pNetwork        The network the frame is being sent to.
 * @param   pIfSender       The interface sending the frame. This is NULL if it's the trunk.
 * @param   fSrc            The source flags. This 0 if it's not from the trunk.
 * @param   pSG             Pointer to the gather list.
 * @param   fTrunkLocked    Whether the caller owns the out-bound trunk lock.
 * @param   pEthHdr         Pointer to the ethernet header.
 */
static bool intnetR0NetworkSendUnicast(PINTNETNETWORK pNetwork, PINTNETIF pIfSender, uint32_t fSrc, PINTNETSG pSG, bool fTrunkLocked, PCINTNETETHERHDR pEthHdr)
{
    /*
     * Only send to the interfaces with matching a MAC address.
     */
    Log2(("Dst=%.6Rhxs\n", &pEthHdr->MacDst));
    bool fExactIntNetRecipient = false;
    for (PINTNETIF pIf = pNetwork->pIFs; pIf; pIf = pIf->pNext)
    {
        Log2(("Dst=%.6Rhxs ?==? %.6Rhxs\n", &pEthHdr->MacDst, &pIf->Mac));
        bool fIt = false;
        if (    (   !pIf->fMacSet
                 || (fIt = !memcmp(&pIf->Mac, &pEthHdr->MacDst, sizeof(pIf->Mac))) )
            ||  (   pIf->fPromiscuous
                 && !(pNetwork->fFlags & (INTNET_OPEN_FLAGS_IGNORE_PROMISC | INTNET_OPEN_FLAGS_QUIETLY_IGNORE_PROMISC))
                 && pIf != pIfSender /* promiscuous mode: omit the sender */))
        {
            fExactIntNetRecipient |= fIt;
            intnetR0IfSend(pIf, pSG);
        }
    }

    /*
     * Send it to the trunk? Only consider this if we didn't find an recipient
     * or if the trunk is in some form or promiscuous mode.
     */
    PINTNETTRUNKIF pTrunkIf = pNetwork->pTrunkIF;
    if (    pIfSender
        &&  pTrunkIf
        &&  pTrunkIf->pIfPort)
    {
        uint32_t fDst = 0;
        if (    pTrunkIf->fPromiscuousWire
            &&  !(pNetwork->fFlags & (INTNET_OPEN_FLAGS_IGNORE_PROMISC | INTNET_OPEN_FLAGS_QUIETLY_IGNORE_PROMISC | INTNET_OPEN_FLAGS_IGNORE_PROMISC_TRUNK_WIRE | INTNET_OPEN_FLAGS_QUIETLY_IGNORE_PROMISC_TRUNK_WIRE)) )
            fDst |= INTNETTRUNKDIR_WIRE;
        if (    !(pNetwork->fFlags & (INTNET_OPEN_FLAGS_IGNORE_PROMISC | INTNET_OPEN_FLAGS_QUIETLY_IGNORE_PROMISC | INTNET_OPEN_FLAGS_IGNORE_PROMISC_TRUNK_HOST | INTNET_OPEN_FLAGS_QUIETLY_IGNORE_PROMISC_TRUNK_HOST))
            ||  pTrunkIf->pIfPort->pfnIsPromiscuous(pTrunkIf->pIfPort) )
            fDst |= INTNETTRUNKDIR_HOST;
        else if (   !fExactIntNetRecipient      /* if you have duplicate mac addresses, you're screwed. */
                 && pTrunkIf->pIfPort->pfnIsHostMac(pTrunkIf->pIfPort, &pEthHdr->MacDst))
            fDst |= INTNETTRUNKDIR_HOST;
        if (fDst)
            intnetR0TrunkIfSend(pTrunkIf, pNetwork, fDst, pSG, fTrunkLocked);
    }

    return fExactIntNetRecipient;
}


/**
 * Sends a frame.
 *
 * This function will distribute the frame to the interfaces it is addressed to.
 * It will also update the MAC address of the sender.
 *
 * The caller must own the network mutex.
 *
 * @returns true if it's addressed to someone on the network, otherwise false.
 * @param   pNetwork        The network the frame is being sent to.
 * @param   pIfSender       The interface sending the frame. This is NULL if it's the trunk.
 * @param   fSrc            The source flags. This 0 if it's not from the trunk.
 * @param   pSG             Pointer to the gather list.
 * @param   fTrunkLocked    Whether the caller owns the out-bound trunk lock.
 */
static bool intnetR0NetworkSend(PINTNETNETWORK pNetwork, PINTNETIF pIfSender, uint32_t fSrc, PINTNETSG pSG, bool fTrunkLocked)
{
    bool fRc = false;

    /*
     * Assert reality.
     */
    AssertPtr(pNetwork);
    AssertPtrNull(pIfSender);
    Assert(pIfSender ? fSrc == 0 : fSrc != 0);
    Assert(pNetwork == pIfSender->pNetwork);
    AssertPtr(pSG);
    Assert(pSG->cSegsUsed >= 1);
    Assert(pSG->cSegsUsed <= pSG->cSegsAlloc);
    if (pSG->cbTotal < sizeof(INTNETETHERHDR))
        return fRc;

    /*
     * Send statistics.
     */
    STAM_REL_COUNTER_INC(&pIfSender->pIntBuf->cStatSends);
    STAM_REL_COUNTER_ADD(&pIfSender->pIntBuf->cbStatSend, pSG->cbTotal);

    /*
     * Get the ethernet header (might theoretically involve multiple segments).
     */
    INTNETETHERHDR EthHdr;
    if (RT_LIKELY(pSG->aSegs[0].cb >= sizeof(EthHdr)))
        EthHdr = *(PCINTNETETHERHDR)pSG->aSegs[0].pv;
    else
    {
        uint8_t *pbDst = (uint8_t *)&EthHdr;
        size_t   cbLeft = sizeof(EthHdr);
        for (unsigned iSeg = 0; cbLeft && iSeg < pSG->cSegsUsed; iSeg++)
        {
            size_t cb = RT_MIN(cbLeft, pSG->aSegs[iSeg].cb);
            memcpy(pbDst, pSG->aSegs[iSeg].pv, cb);
            pbDst += cb;
            cbLeft -= cb;
        }
        AssertReturn(!cbLeft, false);
    }

    /*
     * Inspect the header updating the mac address of the sender in the process.
     */
    if (    pIfSender
        &&  memcmp(&EthHdr.MacSrc, &pIfSender->Mac, sizeof(pIfSender->Mac)))
    {
        /** @todo stats */
        Log2(("IF MAC: %.6Rhxs -> %.6Rhxs\n", &pIfSender->Mac, &EthHdr.MacSrc));
        pIfSender->Mac = EthHdr.MacSrc;
        pIfSender->fMacSet = true;
    }

    /*
     * Distribute the frame.
     */
    if (RT_UNLIKELY(EthHdr.MacDst.au8[0] & 1))      /* multicast address */
        fRc = intnetR0NetworkSendMulticast(pNetwork, pIfSender, fSrc, pSG, fTrunkLocked, &EthHdr);
    else if (   EthHdr.MacDst.au16[0] == 0xffff     /* broadcast address. */
             && EthHdr.MacDst.au16[1] == 0xffff
             && EthHdr.MacDst.au16[2] == 0xffff)
        fRc = intnetR0NetworkSendBroadcast(pNetwork, pIfSender, pSG, fTrunkLocked);
    else
        fRc = intnetR0NetworkSendUnicast(pNetwork, pIfSender, fSrc, pSG, fTrunkLocked, &EthHdr);
    return fRc;
}


/**
 * Sends one or more frames.
 *
 * The function will first the frame which is passed as the optional
 * arguments pvFrame and cbFrame. These are optional since it also
 * possible to chain together one or more frames in the send buffer
 * which the function will process after considering it's arguments.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance data.
 * @param   hIf         The interface handle.
 * @param   pvFrame     Pointer to the frame. Optional, please don't use.
 * @param   cbFrame     Size of the frame. Optional, please don't use.
 */
INTNETR0DECL(int) INTNETR0IfSend(PINTNET pIntNet, INTNETIFHANDLE hIf, const void *pvFrame, unsigned cbFrame)
{
    LogFlow(("INTNETR0IfSend: pIntNet=%p hIf=%RX32 pvFrame=%p cbFrame=%u\n", pIntNet, hIf, pvFrame, cbFrame));

    /*
     * Validate input and translate the handle.
     */
    /** @todo add an exctra reference to the interface! */
    AssertReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
        return VERR_INVALID_HANDLE;
    if (pvFrame && cbFrame)
    {
        AssertReturn(cbFrame < 0x8000, VERR_INVALID_PARAMETER);
        AssertPtrReturn(pvFrame, VERR_INVALID_PARAMETER);
        AssertPtrReturn((uint8_t *)pvFrame + cbFrame - 1, VERR_INVALID_PARAMETER);

        /* This is the better place to crash, probe the buffer. */
        ASMProbeReadBuffer(pvFrame, cbFrame);
    }

    /*
     * Lock the network. If there is a trunk retain it and grab its
     * out-bound lock (this requires leaving the network lock first).
     * Grabbing the out-bound lock here simplifies things quite a bit
     * later on, so while this is excessive and a bit expensive it's
     * not worth caring about right now.
     */
    PINTNETNETWORK pNetwork = pIf->pNetwork;
    int rc = RTSemFastMutexRequest(pNetwork->FastMutex);
    if (RT_FAILURE(rc))
        return rc;
    PINTNETTRUNKIF pTrunkIf = intnetR0TrunkIfRetain(pNetwork->pTrunkIF);
    if (pTrunkIf)
    {
        RTSemFastMutexRelease(pIf->pNetwork->FastMutex);

        if (!intnetR0TrunkIfOutLock(pTrunkIf))
        {
            intnetR0TrunkIfRelease(pTrunkIf);
            return VERR_SEM_DESTROYED;
        }

        rc = RTSemFastMutexRequest(pNetwork->FastMutex);
        if (RT_FAILURE(rc))
        {
            intnetR0TrunkIfOutUnlock(pTrunkIf);
            intnetR0TrunkIfRelease(pTrunkIf);
            return rc;
        }
    }

    INTNETSG Sg; /** @todo this will have to be changed if we're going to use async sending
                  * with buffer sharing for some OS or service. Darwin copies everything so
                  * I won't bother allocating and managing SGs rigth now. Sorry. */

    /*
     * Process the argument.
     */
    if (pvFrame && cbFrame)
    {
        intnetR0SgInitTemp(&Sg, (void *)pvFrame, cbFrame);
        intnetR0NetworkSend(pIf->pNetwork, pIf, 0, &Sg, !!pTrunkIf);
    }

    /*
     * Process the send buffer.
     */
    while (pIf->pIntBuf->Send.offRead != pIf->pIntBuf->Send.offWrite)
    {
        /* Send the frame if the type is sane. */
        PINTNETHDR pHdr = (PINTNETHDR)((uintptr_t)pIf->pIntBuf + pIf->pIntBuf->Send.offRead);
        if (pHdr->u16Type == INTNETHDR_TYPE_FRAME)
        {
            void *pvCurFrame = INTNETHdrGetFramePtr(pHdr, pIf->pIntBuf);
            if (pvCurFrame)
            {
                intnetR0SgInitTemp(&Sg, pvCurFrame, pHdr->cbFrame);
                intnetR0NetworkSend(pIf->pNetwork, pIf, 0, &Sg, !!pTrunkIf);
            }
        }
        /* else: ignore the frame */

        /* Skip to the next frame. */
        INTNETRingSkipFrame(pIf->pIntBuf, &pIf->pIntBuf->Send);
    }

    /*
     * Release the semaphore(s) and release references.
     */
    rc = RTSemFastMutexRelease(pIf->pNetwork->FastMutex);
    if (pTrunkIf)
    {
        intnetR0TrunkIfOutUnlock(pTrunkIf);
        intnetR0TrunkIfRelease(pTrunkIf);
    }

    return rc;
}


/**
 * VMMR0 request wrapper for INTNETR0IfSend.
 *
 * @returns see INTNETR0IfSend.
 * @param   pIntNet         The internal networking instance.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0IfSendReq(PINTNET pIntNet, PINTNETIFSENDREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0IfSend(pIntNet, pReq->hIf, NULL, 0);
}


/**
 * Maps the default buffer into ring 3.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance data.
 * @param   hIf         The interface handle.
 * @param   ppRing3Buf  Where to store the address of the ring-3 mapping.
 */
INTNETR0DECL(int) INTNETR0IfGetRing3Buffer(PINTNET pIntNet, INTNETIFHANDLE hIf, R3PTRTYPE(PINTNETBUF) *ppRing3Buf)
{
    LogFlow(("INTNETR0IfGetRing3Buffer: pIntNet=%p hIf=%RX32 ppRing3Buf=%p\n", pIntNet, hIf, ppRing3Buf));

    /*
     * Validate input.
     */
    AssertReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
        return VERR_INVALID_HANDLE;
    AssertPtrReturn(ppRing3Buf, VERR_INVALID_PARAMETER);

    /*
     * ASSUMES that only the process that created an interface can use it.
     * ASSUMES that we created the ring-3 mapping when selecting or
     * allocating the buffer.
     */
    int rc = RTSemFastMutexRequest(pIf->pNetwork->FastMutex);
    if (RT_FAILURE(rc))
        return rc;

    *ppRing3Buf = pIf->pIntBufR3;

    rc = RTSemFastMutexRelease(pIf->pNetwork->FastMutex);
    LogFlow(("INTNETR0IfGetRing3Buffer: returns %Rrc *ppRing3Buf=%p\n", rc, *ppRing3Buf));
    return rc;
}


/**
 * VMMR0 request wrapper for INTNETR0IfGetRing3Buffer.
 *
 * @returns see INTNETR0IfGetRing3Buffer.
 * @param   pIntNet         The internal networking instance.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0IfGetRing3BufferReq(PINTNET pIntNet, PINTNETIFGETRING3BUFFERREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0IfGetRing3Buffer(pIntNet, pReq->hIf, &pReq->pRing3Buf);
}


/**
 * Gets the ring-0 address of the current buffer.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance data.
 * @param   hIf         The interface handle.
 * @param   ppRing0Buf  Where to store the address of the ring-3 mapping.
 */
INTNETR0DECL(int) INTNETR0IfGetRing0Buffer(PINTNET pIntNet, INTNETIFHANDLE hIf, PINTNETBUF *ppRing0Buf)
{
    LogFlow(("INTNETR0IfGetRing0Buffer: pIntNet=%p hIf=%RX32 ppRing0Buf=%p\n", pIntNet, hIf, ppRing0Buf));

    /*
     * Validate input.
     */
    AssertPtrReturn(ppRing0Buf, VERR_INVALID_PARAMETER);
    *ppRing0Buf = NULL;
    AssertPtrReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
        return VERR_INVALID_HANDLE;

    /*
     * Grab the lock and get the data.
     * ASSUMES that the handle isn't closed while we're here.
     */
    int rc = RTSemFastMutexRequest(pIf->pNetwork->FastMutex);
    if (RT_FAILURE(rc))
        return rc;

    *ppRing0Buf = pIf->pIntBuf;

    rc = RTSemFastMutexRelease(pIf->pNetwork->FastMutex);
    LogFlow(("INTNETR0IfGetRing0Buffer: returns %Rrc *ppRing0Buf=%p\n", rc, *ppRing0Buf));
    return rc;
}


#if 0
/**
 * Gets the physical addresses of the default interface buffer.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance data.
 * @param   hIF         The interface handle.
 * @param   paPages     Where to store the addresses. (The reserved fields will be set to zero.)
 * @param   cPages
 */
INTNETR0DECL(int) INTNETR0IfGetPhysBuffer(PINTNET pIntNet, INTNETIFHANDLE hIf, PSUPPAGE paPages, unsigned cPages)
{
    /*
     * Validate input.
     */
    AssertReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
        return VERR_INVALID_HANDLE;
    AssertPtrReturn(paPages, VERR_INVALID_PARAMETER);
    AssertPtrReturn((uint8_t *)&paPages[cPages] - 1, VERR_INVALID_PARAMETER);

    /*
     * Grab the lock and get the data.
     * ASSUMES that the handle isn't closed while we're here.
     */
    int rc = RTSemFastMutexRequest(pIf->pNetwork->FastMutex);
    if (RT_FAILURE(rc))
        return rc;

    /** @todo make a SUPR0 api for obtaining the array. SUPR0/IPRT is keeping track of everything, there
     * is no need for any extra bookkeeping here.. */
    //*ppRing0Buf = pIf->pIntBuf;

    //return RTSemFastMutexRelease(pIf->pNetwork->FastMutex);
    RTSemFastMutexRelease(pIf->pNetwork->FastMutex);
    return VERR_NOT_IMPLEMENTED;
}
#endif


/**
 * Sets the promiscuous mode property of an interface.
 *
 * @returns VBox status code.
 * @param   pIntNet         The instance handle.
 * @param   hIf             The interface handle.
 * @param   fPromiscuous    Set if the interface should be in promiscuous mode, clear if not.
 */
INTNETR0DECL(int) INTNETR0IfSetPromiscuousMode(PINTNET pIntNet, INTNETIFHANDLE hIf, bool fPromiscuous)
{
    LogFlow(("INTNETR0IfSetPromiscuousMode: pIntNet=%p hIf=%RX32 fPromiscuous=%d\n", pIntNet, hIf, fPromiscuous));

    /*
     * Validate & translate input.
     */
    AssertReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
    {
        LogFlow(("INTNETR0IfSetPromiscuousMode: returns VERR_INVALID_HANDLE\n"));
        return VERR_INVALID_HANDLE;
    }

    /*
     * Grab the network semaphore and make the change.
     */
    PINTNETNETWORK pNetwork = pIf->pNetwork;
    if (!pNetwork)
        return VERR_WRONG_ORDER;
    int rc = RTSemFastMutexRequest(pNetwork->FastMutex);
    if (RT_FAILURE(rc))
        return rc;

    if (pIf->fPromiscuous != fPromiscuous)
    {
        Log(("INTNETR0IfSetPromiscuousMode: hIf=%RX32: Changed from %d -> %d\n",
             hIf, !fPromiscuous, !!fPromiscuous));
        ASMAtomicUoWriteBool(&pIf->fPromiscuous, fPromiscuous);
    }

    RTSemFastMutexRelease(pNetwork->FastMutex);
    return VINF_SUCCESS;
}


/**
 * VMMR0 request wrapper for INTNETR0IfSetPromiscuousMode.
 *
 * @returns see INTNETR0IfSetPromiscuousMode.
 * @param   pIntNet         The internal networking instance.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0IfSetPromiscuousModeReq(PINTNET pIntNet, PINTNETIFSETPROMISCUOUSMODEREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0IfSetPromiscuousMode(pIntNet, pReq->hIf, pReq->fPromiscuous);
}


/**
 * Worker for intnetR0IfSetActive.
 *
 * This function will update the active interface count on the network and
 * activate or deactivate the trunk connection if necessary. Note that in
 * order to do this it is necessary to abandond the network semaphore.
 *
 * @returns VBox status code.
 * @param   pNetwork        The network.
 * @param   fIf             The interface.
 * @param   fActive         What to do.
 */
static int intnetR0NetworkSetIfActive(PINTNETNETWORK pNetwork, PINTNETIF pIf, bool fActive)
{
    /* quick santiy check */
    AssertPtr(pNetwork);
    AssertPtr(pIf);

    /*
     * If we've got a trunk, lock it now in case we need to call out, and
     * then lock the network.
     */
    PINTNETTRUNKIF pTrunkIf = pNetwork->pTrunkIF;
    if (pTrunkIf && !intnetR0TrunkIfOutLock(pTrunkIf))
        return VERR_SEM_DESTROYED;

    int rc = RTSemFastMutexRequest(pNetwork->FastMutex); AssertRC(rc);
    if (RT_SUCCESS(rc))
    {
        bool fNetworkLocked = true;

        /*
         * Make the change if necessary.
         */
        if (pIf->fActive != fActive)
        {
            pIf->fActive = fActive;

            uint32_t const cActiveIFs = pNetwork->cActiveIFs;
            Assert((int32_t)cActiveIFs + (fActive ? 1 : -1) >= 0);
            pNetwork->cActiveIFs += fActive ? 1 : -1;

            if (    pTrunkIf
                &&  (   !pNetwork->cActiveIFs
                     || !cActiveIFs))
            {
                /*
                 * We'll have to change the trunk status, so, leave
                 * the network semaphore so we don't create any deadlocks.
                 */
                int rc2 = RTSemFastMutexRelease(pNetwork->FastMutex); AssertRC(rc2);
                fNetworkLocked = false;

                if (pTrunkIf->pIfPort)
                    pTrunkIf->pIfPort->pfnSetActive(pTrunkIf->pIfPort, fActive);
            }
        }

        if (fNetworkLocked)
            RTSemFastMutexRelease(pNetwork->FastMutex);
    }
    if (pTrunkIf)
        intnetR0TrunkIfOutUnlock(pTrunkIf);
    return rc;
}


/**
 * Activates or deactivates a interface.
 *
 * This is used to enable and disable the trunk connection on demans as well as
 * know when not to expect an interface to want to receive packets.
 *
 * @returns VBox status code.
 * @param   pIf         The interface.
 * @param   fActive     What to do.
 */
static int intnetR0IfSetActive(PINTNETIF pIf, bool fActive)
{
    /* quick sanity check */
    AssertPtrReturn(pIf, VERR_INVALID_POINTER);

    /*
     * Hand it to the network since it might involve the trunk
     * and things are tricky there wrt to locking order.
     */
    PINTNETNETWORK pNetwork = pIf->pNetwork;
    if (!pNetwork)
        return VERR_WRONG_ORDER;
    return intnetR0NetworkSetIfActive(pNetwork, pIf, fActive);
}


/**
 * Wait for the interface to get signaled.
 * The interface will be signaled when is put into the receive buffer.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance handle.
 * @param   hIf         The interface handle.
 * @param   cMillies    Number of milliseconds to wait. RT_INDEFINITE_WAIT should be
 *                      used if indefinite wait is desired.
 */
INTNETR0DECL(int) INTNETR0IfWait(PINTNET pIntNet, INTNETIFHANDLE hIf, uint32_t cMillies)
{
    LogFlow(("INTNETR0IfWait: pIntNet=%p hIf=%RX32 cMillies=%u\n", pIntNet, hIf, cMillies));

    /*
     * Get and validate essential handles.
     */
    AssertReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0Handle2IFPtr(&pIntNet->IfHandles, hIf);
    if (!pIf)
    {
        LogFlow(("INTNETR0IfWait: returns VERR_INVALID_HANDLE\n"));
        return VERR_INVALID_HANDLE;
    }
    const INTNETIFHANDLE    hIfSelf = pIf->hIf;
    const RTSEMEVENT        Event = pIf->Event;
    if (    hIfSelf != hIf
        &&  Event != NIL_RTSEMEVENT)
    {
        LogFlow(("INTNETR0IfWait: returns VERR_SEM_DESTROYED\n"));
        return VERR_SEM_DESTROYED;
    }

    /*
     * It is tempting to check if there is data to be read here,
     * but the problem with such an approach is that it will cause
     * one unnecessary supervisor->user->supervisor trip. There is
     * already a slight risk for such, so no need to increase it.
     */

    /*
     * Increment the number of waiters before starting the wait.
     * Upon wakeup we must assert reality checking that we're not
     * already destroyed or in the process of being destroyed.
     */
    ASMAtomicIncU32(&pIf->cSleepers);
    int rc = RTSemEventWaitNoResume(Event, cMillies);
    if (pIf->Event == Event)
    {
        ASMAtomicDecU32(&pIf->cSleepers);
        if (pIf->hIf != hIf)
            rc = VERR_SEM_DESTROYED;
    }
    else
        rc = VERR_SEM_DESTROYED;
    LogFlow(("INTNETR0IfWait: returns %Rrc\n", rc));
    return rc;
}


/**
 * VMMR0 request wrapper for INTNETR0IfWait.
 *
 * @returns see INTNETR0IfWait.
 * @param   pIntNet         The internal networking instance.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0IfWaitReq(PINTNET pIntNet, PINTNETIFWAITREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0IfWait(pIntNet, pReq->hIf, pReq->cMillies);
}


/**
 * Close an interface.
 *
 * @returns VBox status code.
 * @param   pIntNet     The instance handle.
 * @param   hIf         The interface handle.
 */
INTNETR0DECL(int) INTNETR0IfClose(PINTNET pIntNet, INTNETIFHANDLE hIf)
{
    LogFlow(("INTNETR0IfClose: pIntNet=%p hIf=%RX32\n", pIntNet, hIf));

    /*
     * Validate, get and free the handle.
     */
    AssertPtrReturn(pIntNet, VERR_INVALID_PARAMETER);
    PINTNETIF pIf = intnetR0HandleFree(&pIntNet->IfHandles, hIf);
    if (!pIf)
        return VERR_INVALID_HANDLE;
    ASMAtomicWriteU32(&pIf->hIf, INTNET_HANDLE_INVALID);

    /*
     * Release our reference to the interface object.
     */
    int rc = SUPR0ObjRelease(pIf->pvObj, pIf->pSession);
    LogFlow(("INTNETR0IfClose: returns %Rrc\n", rc));
    return rc;
}


/**
 * VMMR0 request wrapper for INTNETR0IfCloseReq.
 *
 * @returns see INTNETR0IfClose.
 * @param   pIntNet         The internal networking instance.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0IfCloseReq(PINTNET pIntNet, PINTNETIFCLOSEREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0IfClose(pIntNet, pReq->hIf);
}


/**
 * Interface destructor callback.
 * This is called for reference counted objectes when the count reaches 0.
 *
 * @param   pvObj       The object pointer.
 * @param   pvUser1     Pointer to the interface.
 * @param   pvUser2     Pointer to the INTNET instance data.
 */
static DECLCALLBACK(void) intnetR0IfDestruct(void *pvObj, void *pvUser1, void *pvUser2)
{
    LogFlow(("intnetR0IfDestruct: pvObj=%p pvUser1=%p pvUser2=%p\n", pvObj, pvUser1, pvUser2));
    PINTNETIF pIf = (PINTNETIF)pvUser1;
    PINTNET   pIntNet = (PINTNET)pvUser2;

    RTSemFastMutexRequest(pIntNet->FastMutex);

    /*
     * Delete the interface handle so the object no longer can be opened.
     */
    INTNETIFHANDLE hIf = ASMAtomicXchgU32(&pIf->hIf, INTNET_HANDLE_INVALID);
    if (hIf != INTNET_HANDLE_INVALID)
        intnetR0HandleFree(&pIntNet->IfHandles, hIf);

    /*
     * If we've got a network deactivate and unlink ourselves from it.
     * Because of cleanup order we might be an orphan now.
     */
    PINTNETNETWORK pNetwork = pIf->pNetwork;
    if (pNetwork)
    {
        intnetR0IfSetActive(pIf, false);

        if (pNetwork->pIFs == pIf)
            pNetwork->pIFs = pIf->pNext;
        else
        {
            PINTNETIF pPrev = pNetwork->pIFs;
            while (pPrev)
            {
                if (pPrev->pNext == pIf)
                {
                    pPrev->pNext = pIf->pNext;
                    break;
                }
                pPrev = pPrev->pNext;
            }
            Assert(pPrev);
        }
        pIf->pNext = NULL;

        /*
         * Release our reference to the network.
         */
        RTSemFastMutexRelease(pIntNet->FastMutex);

        SUPR0ObjRelease(pNetwork->pvObj, pIf->pSession);
        pIf->pNetwork = NULL;
    }
    else
        RTSemFastMutexRelease(pIntNet->FastMutex);

    /*
     * Wakeup anyone waiting on this interface.
     *
     * We *must* make sure they have woken up properly and realized
     * that the interface is no longer valid.
     */
    if (pIf->Event != NIL_RTSEMEVENT)
    {
        RTSEMEVENT Event = pIf->Event;
        ASMAtomicXchgSize(&pIf->Event, NIL_RTSEMEVENT);
        unsigned cMaxWait = 0x1000;
        while (pIf->cSleepers && cMaxWait-- > 0)
        {
            RTSemEventSignal(Event);
            RTThreadYield();
        }
        if (pIf->cSleepers)
        {
            RTThreadSleep(1);

            cMaxWait = pIf->cSleepers;
            while (pIf->cSleepers && cMaxWait-- > 0)
            {
                RTSemEventSignal(Event);
                RTThreadSleep(10);
            }
        }
        RTSemEventDestroy(Event);
    }

    /*
     * Unmap user buffer.
     */
    if (pIf->pIntBuf != pIf->pIntBufDefault)
    {
        /** @todo user buffer */
    }

    /*
     * Unmap and Free the default buffer.
     */
    if (pIf->pIntBufDefault)
    {
        SUPR0MemFree(pIf->pSession, (RTHCUINTPTR)pIf->pIntBufDefault);
        pIf->pIntBufDefault = NULL;
        pIf->pIntBufDefaultR3 = 0;
        pIf->pIntBuf = NULL;
        pIf->pIntBufR3 = 0;
    }

    /*
     * The interface.
     */
    pIf->pvObj = NULL;
    RTMemFree(pIf);
}


/**
 * Creates a new network interface.
 *
 * The call must have opened the network for the new interface
 * and is responsible for closing it on failure. On success
 * it must leave the network opened so the interface destructor
 * can close it.
 *
 * @returns VBox status code.
 * @param   pNetwork    The network.
 * @param   pSession    The session handle.
 * @param   cbSend      The size of the send buffer.
 * @param   cbRecv      The size of the receive buffer.
 * @param   phIf        Where to store the interface handle.
 */
static int intnetR0NetworkCreateIf(PINTNETNETWORK pNetwork, PSUPDRVSESSION pSession, unsigned cbSend, unsigned cbRecv, bool *pfCloseNetwork, PINTNETIFHANDLE phIf)
{
    LogFlow(("intnetR0NetworkCreateIf: pNetwork=%p pSession=%p cbSend=%u cbRecv=%u phIf=%p\n",
             pNetwork, pSession, cbSend, cbRecv, phIf));

    /*
     * Assert input.
     */
    AssertPtr(pNetwork);
    AssertPtr(phIf);
    AssertPtr(pfCloseNetwork);
    *pfCloseNetwork = false;

    /*
     * Allocate and initialize the interface structure.
     */
    PINTNETIF pIf = (PINTNETIF)RTMemAllocZ(sizeof(*pIf));
    if (!pIf)
        return VERR_NO_MEMORY;
    //pIf->pNext = NULL;
    memset(&pIf->Mac, 0xff, sizeof(pIf->Mac)); /* broadcast */
    //pIf->fMacSet = false;
    //pIf->fPromiscuous = false;
    //pIf->fActive = false;
    //pIf->pIntBuf = 0;
    //pIf->pIntBufR3 = NIL_RTR3PTR;
    //pIf->pIntBufDefault = 0;
    //pIf->pIntBufDefaultR3 = NIL_RTR3PTR;
    //pIf->cYields = 0;
    pIf->Event = NIL_RTSEMEVENT;
    //pIf->cSleepers = 0;
    pIf->hIf = INTNET_HANDLE_INVALID;
    pIf->pNetwork = pNetwork;
    pIf->pSession = pSession;
    //pIf->pvObj = NULL;
    int rc = RTSemEventCreate(&pIf->Event);
    if (RT_SUCCESS(rc))
    {
        /*
         * Create the default buffer.
         */
        cbRecv = RT_ALIGN(RT_MAX(cbRecv, sizeof(INTNETHDR) * 4), sizeof(INTNETHDR));
        cbSend = RT_ALIGN(RT_MAX(cbSend, sizeof(INTNETHDR) * 4), sizeof(INTNETHDR));
        const unsigned cbBuf = RT_ALIGN(sizeof(*pIf->pIntBuf), sizeof(INTNETHDR)) + cbRecv + cbSend;
        rc = SUPR0MemAlloc(pIf->pSession, cbBuf, (PRTR0PTR)&pIf->pIntBufDefault, (PRTR3PTR)&pIf->pIntBufDefaultR3);
        if (RT_SUCCESS(rc))
        {
            pIf->pIntBuf = pIf->pIntBufDefault;
            pIf->pIntBufR3 = pIf->pIntBufDefaultR3;
            pIf->pIntBuf->cbBuf = cbBuf;
            pIf->pIntBuf->cbRecv = cbRecv;
            pIf->pIntBuf->cbSend = cbSend;
            /* receive ring buffer. */
            pIf->pIntBuf->Recv.offStart = RT_ALIGN_32(sizeof(*pIf->pIntBuf), sizeof(INTNETHDR));
            pIf->pIntBuf->Recv.offRead  = pIf->pIntBuf->Recv.offStart;
            pIf->pIntBuf->Recv.offWrite = pIf->pIntBuf->Recv.offStart;
            pIf->pIntBuf->Recv.offEnd   = pIf->pIntBuf->Recv.offStart + cbRecv;
            /* send ring buffer. */
            pIf->pIntBuf->Send.offStart = pIf->pIntBuf->Recv.offEnd;
            pIf->pIntBuf->Send.offRead  = pIf->pIntBuf->Send.offStart;
            pIf->pIntBuf->Send.offWrite = pIf->pIntBuf->Send.offStart;
            pIf->pIntBuf->Send.offEnd   = pIf->pIntBuf->Send.offStart + cbSend;

            /*
             * Link the interface to the network.
             */
            rc = RTSemFastMutexRequest(pNetwork->FastMutex);
            if (RT_SUCCESS(rc))
            {
                pIf->pNext = pNetwork->pIFs;
                pNetwork->pIFs = pIf;
                RTSemFastMutexRelease(pNetwork->FastMutex);

                /*
                 * Register the interface with the session.
                 */
                pIf->pvObj = SUPR0ObjRegister(pSession, SUPDRVOBJTYPE_INTERNAL_NETWORK_INTERFACE, intnetR0IfDestruct, pIf, pNetwork->pIntNet);
                if (pIf->pvObj)
                {
                    pIf->hIf = intnetR0HandleAllocate(pNetwork->pIntNet, pIf);
                    if (pIf->hIf != INTNET_HANDLE_INVALID)
                    {
                        /* auto activation */ /** @todo do this manually in the future, ditto for setting the MAC address. */
                        rc = intnetR0IfSetActive(pIf, true /* activate */);
                        AssertRC(rc);

                        *phIf = pIf->hIf;
                        LogFlow(("intnetR0NetworkCreateIf: returns VINF_SUCCESS *phIf=%p\n", *phIf));
                        return VINF_SUCCESS;
                    }
                    rc = VERR_NO_MEMORY;

                    SUPR0ObjRelease(pIf->pvObj, pSession);
                    LogFlow(("intnetR0NetworkCreateIf: returns %Rrc\n", rc));
                    return rc;
                }

                rc = VERR_NO_MEMORY;
                RTSemFastMutexDestroy(pNetwork->FastMutex);
                pNetwork->FastMutex = NIL_RTSEMFASTMUTEX;
            }

            SUPR0MemFree(pIf->pSession, (RTHCUINTPTR)pIf->pIntBufDefault);
            pIf->pIntBufDefault = NULL;
            pIf->pIntBuf = NULL;
        }

        RTSemEventDestroy(pIf->Event);
        pIf->Event = NIL_RTSEMEVENT;
    }
    RTMemFree(pIf);
    LogFlow(("intnetR0NetworkCreateIf: returns %Rrc\n", rc));
    *pfCloseNetwork = true;
    return rc;
}





/** @copydoc INTNETTRUNKSWPORT::pfnSetSGPhys */
static DECLCALLBACK(bool) intnetR0TrunkIfPortSetSGPhys(PINTNETTRUNKSWPORT pSwitchPort, bool fEnable)
{
    PINTNETTRUNKIF pThis = INTNET_SWITCHPORT_2_TRUNKIF(pSwitchPort);
    AssertMsgFailed(("Not implemented because it wasn't required on Darwin\n"));
    return ASMAtomicXchgBool(&pThis->fPhysSG, fEnable);
}


/** @copydoc INTNETTRUNKSWPORT::pfnRecv */
static DECLCALLBACK(bool) intnetR0TrunkIfPortRecv(PINTNETTRUNKSWPORT pSwitchPort, PINTNETSG pSG, uint32_t fSrc)
{
    PINTNETTRUNKIF pThis = INTNET_SWITCHPORT_2_TRUNKIF(pSwitchPort);
    PINTNETNETWORK pNetwork = pThis->pNetwork;

    /* assert some sanity */
    AssertPtrReturn(pNetwork, false);
    AssertReturn(pNetwork->FastMutex != NIL_RTSEMFASTMUTEX, false);
    AssertPtr(pSG);
    Assert(fSrc);

    /*
     * Lock the network and send the frame to it.
     */
    int rc = RTSemFastMutexRequest(pNetwork->FastMutex);
    AssertRCReturn(rc, false);

    bool fRc;
    if (RT_LIKELY(pNetwork->cActiveIFs > 0))
        fRc = intnetR0NetworkSend(pNetwork, NULL, fSrc, pSG, false /* fTrunkLocked */);
    else
        fRc = false; /* don't drop it */

    rc = RTSemFastMutexRelease(pNetwork->FastMutex);
    AssertRC(rc);

    return fRc;
}


/** @copydoc INTNETTRUNKSWPORT::pfnSGRetain */
static DECLCALLBACK(void) intnetR0TrunkIfPortSGRetain(PINTNETTRUNKSWPORT pSwitchPort, PINTNETSG pSG)
{
    PINTNETTRUNKIF pThis = INTNET_SWITCHPORT_2_TRUNKIF(pSwitchPort);
    PINTNETNETWORK pNetwork = pThis->pNetwork;

    /* assert some sanity */
    AssertPtrReturnVoid(pNetwork);
    AssertReturnVoid(pNetwork->FastMutex != NIL_RTSEMFASTMUTEX);
    AssertPtr(pSG);
    Assert(pSG->cUsers > 0);

    /* do it. */
    ++pSG->cUsers;
}


/** @copydoc INTNETTRUNKSWPORT::pfnSGRelease */
static DECLCALLBACK(void) intnetR0TrunkIfPortSGRelease(PINTNETTRUNKSWPORT pSwitchPort, PINTNETSG pSG)
{
    PINTNETTRUNKIF pThis = INTNET_SWITCHPORT_2_TRUNKIF(pSwitchPort);
    PINTNETNETWORK pNetwork = pThis->pNetwork;

    /* assert some sanity */
    AssertPtrReturnVoid(pNetwork);
    AssertReturnVoid(pNetwork->FastMutex != NIL_RTSEMFASTMUTEX);
    AssertPtr(pSG);
    Assert(pSG->cUsers > 0);

    /*
     * Free it?
     */
    if (!--pSG->cUsers)
    {
        /** @todo later */
    }
}


/**
 * Retain the trunk interface.
 *
 * @returns pThis if retained.
 *
 * @param   pThis       The trunk.
 *
 * @remarks Any locks.
 */
static PINTNETTRUNKIF intnetR0TrunkIfRetain(PINTNETTRUNKIF pThis)
{
    if (pThis && pThis->pIfPort)
    {
        pThis->pIfPort->pfnRetain(pThis->pIfPort);
        return pThis;
    }
    return NULL;
}


/**
 * Release the trunk interface.
 *
 * @param   pThis       The trunk.
 */
static void intnetR0TrunkIfRelease(PINTNETTRUNKIF pThis)
{
    if (pThis && pThis->pIfPort)
        pThis->pIfPort->pfnRelease(pThis->pIfPort);
}


/**
 * Takes the out-bound trunk lock.
 *
 * This will ensure that pIfPort is valid.
 *
 * @returns success indicator.
 * @param   pThis       The trunk.
 *
 * @remarks No locks other than the create/destroy one.
 */
static bool intnetR0TrunkIfOutLock(PINTNETTRUNKIF pThis)
{
    AssertPtrReturn(pThis, false);
    int rc = RTSemFastMutexRequest(pThis->FastMutex);
    if (RT_SUCCESS(rc))
    {
        if (RT_LIKELY(pThis->pIfPort))
            return true;
        RTSemFastMutexRelease(pThis->FastMutex);
    }
    else
        AssertMsg(rc == VERR_SEM_DESTROYED, ("%Rrc\n", rc));
    return false;
}


/**
 * Releases the out-bound trunk lock.
 *
 * @param   pThis       The trunk.
 */
static void intnetR0TrunkIfOutUnlock(PINTNETTRUNKIF pThis)
{
    if (pThis)
    {
        int rc = RTSemFastMutexRelease(pThis->FastMutex);
        AssertRC(rc);
    }
}


/**
 * Activates the trunk interface.
 *
 * @param   pThis       The trunk.
 * @param   fActive     What to do with it.
 *
 * @remarks Caller may only own the create/destroy lock.
 */
static void intnetR0TrunkIfActivate(PINTNETTRUNKIF pThis, bool fActive)
{
    if (intnetR0TrunkIfOutLock(pThis))
    {
        pThis->pIfPort->pfnSetActive(pThis->pIfPort, fActive);
        intnetR0TrunkIfOutUnlock(pThis);
    }
}


/**
 * Shutdown the trunk interface.
 *
 * @param   pThis       The trunk.
 * @param   pNetworks   The network.
 *
 * @remarks The caller must *NOT* hold the network lock. The global
 *          create/destroy lock is fine though.
 */
static void intnetR0TrunkIfDestroy(PINTNETTRUNKIF pThis, PINTNETNETWORK pNetwork)
{
    /* assert sanity */
    if (!pThis)
        return;
    AssertPtr(pThis);
    Assert(pThis->pNetwork == pNetwork);
    AssertPtrNull(pThis->pIfPort);

    /*
     * The interface has already been deactivated, we just to wait for
     * it to become idle before we can disconnect and release it.
     */
    PINTNETTRUNKIFPORT pIfPort = pThis->pIfPort;
    if (pIfPort)
    {
        intnetR0TrunkIfOutLock(pThis);

        /* unset it */
        pThis->pIfPort = NULL;

        /* wait in portions so we can complain ever now an then. */
        uint64_t StartTS = RTTimeSystemNanoTS();
        int rc = pIfPort->pfnWaitForIdle(pIfPort, 10*1000);
        if (RT_FAILURE(rc))
        {
            LogRel(("intnet: '%s' did't become idle in %RU64 ns (%Rrc).\n",
                    pNetwork->szName, RTTimeSystemNanoTS() - StartTS, rc));
            Assert(rc == VERR_TIMEOUT);
            while (     RT_FAILURE(rc)
                   &&   RTTimeSystemNanoTS() - StartTS < UINT64_C(30000000000)) /* 30 sec */
                rc = pIfPort->pfnWaitForIdle(pIfPort, 10*1000);
            if (rc == VERR_TIMEOUT)
            {
                LogRel(("intnet: '%s' did't become idle in %RU64 ns (%Rrc).\n",
                        pNetwork->szName, RTTimeSystemNanoTS() - StartTS, rc));
                while (     rc == VERR_TIMEOUT
                       &&   RTTimeSystemNanoTS() - StartTS < UINT64_C(360000000000)) /* 360 sec */
                    rc = pIfPort->pfnWaitForIdle(pIfPort, 30*1000);
                if (RT_FAILURE(rc))
                {
                    LogRel(("intnet: '%s' did't become idle in %RU64 ns (%Rrc), giving up.\n",
                            pNetwork->szName, RTTimeSystemNanoTS() - StartTS, rc));
                    AssertRC(rc);
                }
            }
        }

        /* disconnect & release it. */
        pIfPort->pfnDisconnectAndRelease(pIfPort);
    }

    /*
     * Free up the resources.
     */
    RTSEMFASTMUTEX FastMutex = pThis->FastMutex;
    pThis->FastMutex = NIL_RTSEMFASTMUTEX;
    pThis->pNetwork = NULL;
    RTSemFastMutexRelease(FastMutex);
    RTSemFastMutexDestroy(FastMutex);
    RTMemFree(pThis);
}


/**
 * Creates the trunk connection (if any).
 *
 * @returns VBox status code.
 *
 * @param   pNetwork    The newly created network.
 * @param   pSession    The session handle.
 */
static int intnetR0NetworkCreateTrunkIf(PINTNETNETWORK pNetwork, PSUPDRVSESSION pSession)
{
    const char *pszName;
    switch (pNetwork->enmTrunkType)
    {
        /*
         * The 'None' case, simple.
         */
        case kIntNetTrunkType_None:
        case kIntNetTrunkType_WhateverNone:
            return VINF_SUCCESS;

        /* Can't happen, but makes GCC happy. */
        default:
            return VERR_NOT_IMPLEMENTED;

        /*
         * Translate enum to component factory name.
         */
        case kIntNetTrunkType_NetFlt:
            pszName = "VBoxNetFlt";
            break;
        case kIntNetTrunkType_NetTap:
            pszName = "VBoxNetTap";
            break;
        case kIntNetTrunkType_SrvNat:
            pszName = "VBoxSrvNat";
            break;
    }

    /*
     * Allocate the trunk interface.
     */
    PINTNETTRUNKIF pTrunkIF = (PINTNETTRUNKIF)RTMemAllocZ(sizeof(*pTrunkIF));
    if (!pTrunkIF)
        return VERR_NO_MEMORY;
    pTrunkIF->SwitchPort.u32Version     = INTNETTRUNKSWPORT_VERSION;
    pTrunkIF->SwitchPort.pfnSetSGPhys   = intnetR0TrunkIfPortSetSGPhys;
    pTrunkIF->SwitchPort.pfnRecv        = intnetR0TrunkIfPortRecv;
    pTrunkIF->SwitchPort.pfnSGRetain    = intnetR0TrunkIfPortSGRetain;
    pTrunkIF->SwitchPort.pfnSGRelease   = intnetR0TrunkIfPortSGRelease;
    pTrunkIF->SwitchPort.u32VersionEnd  = INTNETTRUNKSWPORT_VERSION;
    //pTrunkIF->pIfPort = NULL;
    pTrunkIF->pNetwork = pNetwork;
    //pTrunkIF->fPhysSG = false;
    //pTrunkIF->fPromiscuousWire = false;
    int rc = RTSemFastMutexCreate(&pTrunkIF->FastMutex);
    if (RT_SUCCESS(rc))
    {
#ifdef IN_RING0 /* (testcase is ring-3) */
        /*
         * Query the factory we want, then use it create and connect the trunk.
         */
        PINTNETTRUNKFACTORY pTrunkFactory = NULL;
        rc = SUPR0ComponentQueryFactory(pSession, pszName, INTNETTRUNKFACTORY_UUID_STR, (void **)&pTrunkFactory);
        if (RT_SUCCESS(rc))
        {
            rc = pTrunkFactory->pfnCreateAndConnect(pTrunkFactory, pNetwork->szTrunk, &pTrunkIF->SwitchPort, &pTrunkIF->pIfPort);
            pTrunkFactory->pfnRelease(pTrunkFactory);
            if (RT_SUCCESS(rc))
            {
                Assert(pTrunkIF->pIfPort);
                pNetwork->pTrunkIF = pTrunkIF;
                LogFlow(("intnetR0NetworkCreateTrunkIf: VINF_SUCCESS - pszName=%s szTrunk=%s Network=%s\n",
                         rc, pszName, pNetwork->szTrunk, pNetwork->szName));
                return VINF_SUCCESS;
            }
        }
#endif /* IN_RING0 */
        RTSemFastMutexDestroy(pTrunkIF->FastMutex);
    }
    RTMemFree(pTrunkIF);
    LogFlow(("intnetR0NetworkCreateTrunkIf: %Rrc - pszName=%s szTrunk=%s Network=%s\n",
             rc, pszName, pNetwork->szTrunk, pNetwork->szName));
    return rc;
}



/**
 * Close a network which was opened/created using intnetR0OpenNetwork()/intnetR0CreateNetwork().
 *
 * @param   pNetwork    The network to close.
 * @param   pSession    The session handle.
 */
static int intnetR0NetworkClose(PINTNETNETWORK pNetwork, PSUPDRVSESSION pSession)
{
    LogFlow(("intnetR0NetworkClose: pNetwork=%p pSession=%p\n", pNetwork, pSession));
    AssertPtrReturn(pSession, VERR_INVALID_PARAMETER);
    AssertPtrReturn(pNetwork, VERR_INVALID_PARAMETER);

    int rc = SUPR0ObjRelease(pNetwork->pvObj, pSession);
    LogFlow(("intnetR0NetworkClose: return %Rrc\n", rc));
    return rc;
}


/**
 * Object destructor callback.
 * This is called for reference counted objectes when the count reaches 0.
 *
 * @param   pvObj       The object pointer.
 * @param   pvUser1     Pointer to the network.
 * @param   pvUser2     Pointer to the INTNET instance data.
 */
static DECLCALLBACK(void) intnetR0NetworkDestruct(void *pvObj, void *pvUser1, void *pvUser2)
{
    LogFlow(("intnetR0NetworkDestruct: pvObj=%p pvUser1=%p pvUser2=%p\n", pvObj, pvUser1, pvUser2));
    PINTNETNETWORK  pNetwork = (PINTNETNETWORK)pvUser1;
    PINTNET         pIntNet = (PINTNET)pvUser2;
    Assert(pNetwork->pIntNet == pIntNet);

    /* take the create/destroy sem. */
    RTSemFastMutexRequest(pIntNet->FastMutex);

    /*
     * Deactivate the trunk connection first (if any).
     */
    if (pNetwork->pTrunkIF)
        intnetR0TrunkIfActivate(pNetwork->pTrunkIF, false /* fActive */);

    /*
     * Unlink the network.
     * Note that it needn't be in the list if we failed during creation.
     */
    PINTNETNETWORK pPrev = pIntNet->pNetworks;
    if (pPrev == pNetwork)
        pIntNet->pNetworks = pNetwork->pNext;
    else
    {
        for (; pPrev; pPrev = pPrev->pNext)
            if (pPrev->pNext == pNetwork)
            {
                pPrev->pNext = pNetwork->pNext;
                break;
            }
    }
    pNetwork->pNext = NULL;
    pNetwork->pvObj = NULL;

    /*
     * Because of the undefined order of the per session object dereferencing when closing a session,
     * we have to handle the case where the network is destroyed before the interfaces. We'll
     * deal with this by simply orphaning the interfaces.
     */
    RTSemFastMutexRequest(pNetwork->FastMutex);

    PINTNETIF pCur = pNetwork->pIFs;
    while (pCur)
    {
        PINTNETIF pNext = pCur->pNext;
        pCur->pNext    = NULL;
        pCur->pNetwork = NULL;
        pCur = pNext;
    }

    /* Grab and zap the trunk pointer before leaving the mutex. */
    PINTNETTRUNKIF pTrunkIF = pNetwork->pTrunkIF;
    pNetwork->pTrunkIF = NULL;

    RTSemFastMutexRelease(pNetwork->FastMutex);

    /*
     * If there is a trunk, delete it.
     * Note that this may tak a while if we're unlucky...
     */
    if (pTrunkIF)
        intnetR0TrunkIfDestroy(pTrunkIF, pNetwork);

    /*
     * Free resources.
     */
    RTSemFastMutexDestroy(pNetwork->FastMutex);
    pNetwork->FastMutex = NIL_RTSEMFASTMUTEX;
    RTMemFree(pNetwork);

    /* release the create/destroy sem. (can be done before trunk destruction.) */
    RTSemFastMutexRelease(pIntNet->FastMutex);
}


/**
 * Opens an existing network.
 *
 * @returns VBox status code.
 * @param   pIntNet         The instance data.
 * @param   pSession        The current session.
 * @param   pszNetwork      The network name. This has a valid length.
 * @param   enmTrunkType    The trunk type.
 * @param   pszTrunk        The trunk name. Its meaning is specfic to the type.
 * @param   fFlags          Flags, see INTNET_OPEN_FLAGS_*.
 * @param   ppNetwork       Where to store the pointer to the network on success.
 */
static int intnetR0OpenNetwork(PINTNET pIntNet, PSUPDRVSESSION pSession, const char *pszNetwork, INTNETTRUNKTYPE enmTrunkType,
                               const char *pszTrunk, uint32_t fFlags, PINTNETNETWORK *ppNetwork)
{
    LogFlow(("intnetR0OpenNetwork: pIntNet=%p pSession=%p pszNetwork=%p:{%s} enmTrunkType=%d pszTrunk=%p:{%s} fFlags=%#x ppNetwork=%p\n",
             pIntNet, pSession, pszNetwork, pszNetwork, enmTrunkType, pszTrunk, pszTrunk, fFlags, ppNetwork));

    /* just pro forma validation, the caller is internal. */
    AssertPtr(pIntNet);
    AssertPtr(pSession);
    AssertPtr(pszNetwork);
    Assert(enmTrunkType > kIntNetTrunkType_Invalid && enmTrunkType < kIntNetTrunkType_End);
    AssertPtr(pszTrunk);
    Assert(!(fFlags & ~(INTNET_OPEN_FLAGS_MASK)));
    AssertPtr(ppNetwork);
    *ppNetwork = NULL;

    /*
     * Search networks by name.
     */
    PINTNETNETWORK pCur;
    uint8_t cchName = strlen(pszNetwork);
    Assert(cchName && cchName < sizeof(pCur->szName)); /* caller ensures this */

    pCur = pIntNet->pNetworks;
    while (pCur)
    {
        if (    pCur->cchName == cchName
            &&  !memcmp(pCur->szName, pszNetwork, cchName))
        {
            /*
             * Found the network, now check that we have the same ideas
             * about the trunk setup and security.
             */
            int rc;
            if (    enmTrunkType == kIntNetTrunkType_WhateverNone
                ||  (   pCur->enmTrunkType == enmTrunkType
                     && !strcmp(pCur->szTrunk, pszTrunk)))
            {
                if (!((pCur->fFlags ^ fFlags) & INTNET_OPEN_FLAGS_SECURITY_XOR_MASK))
                {

                    /*
                     * Increment the reference and check that the session
                     * can access this network.
                     */
                    rc = SUPR0ObjAddRef(pCur->pvObj, pSession);
                    if (RT_SUCCESS(rc))
                    {
                        if (!(pCur->fFlags & INTNET_OPEN_FLAGS_PUBLIC))
                            rc = SUPR0ObjVerifyAccess(pCur->pvObj, pSession, pCur->szName);
                        if (RT_SUCCESS(rc))
                        {
                            pCur->fFlags |= fFlags & INTNET_OPEN_FLAGS_SECURITY_OR_MASK;

                            *ppNetwork = pCur;
                        }
                        else
                            SUPR0ObjRelease(pCur->pvObj, pSession);
                    }
                    else if (rc == VERR_WRONG_ORDER)
                        rc = VERR_NOT_FOUND; /* destruction race, pretend the other isn't there. */
                }
                else
                    rc = VERR_INTNET_INCOMPATIBLE_FLAGS;
            }
            else
                rc = VERR_INTNET_INCOMPATIBLE_TRUNK;

            LogFlow(("intnetR0OpenNetwork: returns %Rrc *ppNetwork=%p\n", rc, *ppNetwork));
            return rc;
        }
        pCur = pCur->pNext;
    }

    LogFlow(("intnetR0OpenNetwork: returns VERR_NOT_FOUND\n"));
    return VERR_NOT_FOUND;
}


/**
 * Creates a new network.
 *
 * The call must own the INTNET::FastMutex and has already attempted
 * opening the network and found it to be non-existing.
 *
 * @returns VBox status code.
 * @param   pIntNet         The instance data.
 * @param   pSession        The session handle.
 * @param   pszNetwork      The name of the network. This must be at least one character long and no longer
 *                          than the INTNETNETWORK::szName.
 * @param   enmTrunkType    The trunk type.
 * @param   pszTrunk        The trunk name. Its meaning is specfic to the type.
 * @param   fFlags          Flags, see INTNET_OPEN_FLAGS_*.
 * @param   ppNetwork       Where to store the network. In the case of failure whatever is returned
 *                          here should be dereferenced outside the INTNET::FastMutex.
 */
static int intnetR0CreateNetwork(PINTNET pIntNet, PSUPDRVSESSION pSession, const char *pszNetwork, INTNETTRUNKTYPE enmTrunkType,
                                 const char *pszTrunk, uint32_t fFlags, PINTNETNETWORK *ppNetwork)
{
    LogFlow(("intnetR0CreateNetwork: pIntNet=%p pSession=%p pszNetwork=%p:{%s} enmTrunkType=%d pszTrunk=%p:{%s} fFlags=%#x ppNetwork=%p\n",
             pIntNet, pSession, pszNetwork, pszNetwork, enmTrunkType, pszTrunk, pszTrunk, fFlags, ppNetwork));

    /* just pro forma validation, the caller is internal. */
    AssertPtr(pIntNet);
    AssertPtr(pSession);
    AssertPtr(pszNetwork);
    Assert(enmTrunkType > kIntNetTrunkType_Invalid && enmTrunkType < kIntNetTrunkType_End);
    AssertPtr(pszTrunk);
    Assert(!(fFlags & ~INTNET_OPEN_FLAGS_MASK));
    AssertPtr(ppNetwork);
    *ppNetwork = NULL;

    /*
     * Allocate and initialize.
     */
    PINTNETNETWORK pNew = (PINTNETNETWORK)RTMemAllocZ(sizeof(*pNew));
    if (!pNew)
        return VERR_NO_MEMORY;
    int rc = RTSemFastMutexCreate(&pNew->FastMutex);
    if (RT_SUCCESS(rc))
    {
        //pNew->pIFs = NULL;
        pNew->pIntNet = pIntNet;
        //pNew->cActiveIFs = 0;
        pNew->fFlags = fFlags;
        size_t cchName = strlen(pszNetwork);
        pNew->cchName = cchName;
        Assert(cchName && cchName < sizeof(pNew->szName));  /* caller's responsibility. */
        memcpy(pNew->szName, pszNetwork, cchName);          /* '\0' by alloc. */
        pNew->enmTrunkType = enmTrunkType;
        Assert(strlen(pszTrunk) < sizeof(pNew->szTrunk));   /* caller's responsibility. */
        strcpy(pNew->szTrunk, pszTrunk);

        /*
         * Register the object in the current session and link it into the network list.
         */
        pNew->pvObj = SUPR0ObjRegister(pSession, SUPDRVOBJTYPE_INTERNAL_NETWORK, intnetR0NetworkDestruct, pNew, pIntNet);
        if (pNew->pvObj)
        {
            pNew->pNext = pIntNet->pNetworks;
            pIntNet->pNetworks = pNew;

            /*
             * Check if the current session is actually allowed to create and open
             * the network. It is possible to implement network name based policies
             * and these must be checked now. SUPR0ObjRegister does no such checks.
             */
            rc = SUPR0ObjVerifyAccess(pNew->pvObj, pSession, pNew->szName);
            if (RT_SUCCESS(rc))
            {
                /*
                 * Connect the trunk.
                 */
                rc = intnetR0NetworkCreateTrunkIf(pNew, pSession);
                if (RT_SUCCESS(rc))
                {
                    *ppNetwork = pNew;
                    LogFlow(("intnetR0CreateNetwork: returns VINF_SUCCESS *ppNetwork=%p\n", pNew));
                    return VINF_SUCCESS;
                }
            }

            /*
             * We unlink it here so it cannot be opened when the caller leaves
             * INTNET::FastMutex before dereferencing it.
             */
            Assert(pIntNet->pNetworks == pNew);
            pIntNet->pNetworks = pNew->pNext;
            pNew->pNext = NULL;

            *ppNetwork = pNew;
            LogFlow(("intnetR0CreateNetwork: returns %Rrc\n", rc));
            return rc;
        }
        rc = VERR_NO_MEMORY;

        RTSemFastMutexDestroy(pNew->FastMutex);
        pNew->FastMutex = NIL_RTSEMFASTMUTEX;
    }
    RTMemFree(pNew);
    LogFlow(("intnetR0CreateNetwork: returns %Rrc\n", rc));
    return rc;
}


/**
 * Opens a network interface and connects it to the specified network.
 *
 * @returns VBox status code.
 * @param   pIntNet         The internal network instance.
 * @param   pSession        The session handle.
 * @param   pszNetwork      The network name.
 * @param   enmTrunkType    The trunk type.
 * @param   pszTrunk        The trunk name. Its meaning is specfic to the type.
 * @param   fFlags          Flags, see INTNET_OPEN_FLAGS_*.
 * @param   fRestrictAccess Whether new participants should be subjected to access check or not.
 * @param   cbSend          The send buffer size.
 * @param   cbRecv          The receive buffer size.
 * @param   phIf            Where to store the handle to the network interface.
 */
INTNETR0DECL(int) INTNETR0Open(PINTNET pIntNet, PSUPDRVSESSION pSession, const char *pszNetwork,
                               INTNETTRUNKTYPE enmTrunkType, const char *pszTrunk, uint32_t fFlags,
                               unsigned cbSend, unsigned cbRecv, PINTNETIFHANDLE phIf)
{
    LogFlow(("INTNETR0Open: pIntNet=%p pSession=%p pszNetwork=%p:{%s} enmTrunkType=%d pszTrunk=%p:{%s} fFlags=%#x cbSend=%u cbRecv=%u phIf=%p\n",
             pIntNet, pSession, pszNetwork, pszNetwork, pszTrunk, pszTrunk, enmTrunkType, fFlags, cbSend, cbRecv, phIf));

    /*
     * Validate input.
     */
    AssertPtrReturn(pIntNet, VERR_INVALID_PARAMETER);

    AssertPtrReturn(pszNetwork, VERR_INVALID_PARAMETER);
    const char *pszNetworkEnd = (const char *)memchr(pszNetwork, '\0', INTNET_MAX_NETWORK_NAME);
    AssertReturn(pszNetworkEnd, VERR_INVALID_PARAMETER);
    size_t cchNetwork = pszNetworkEnd - pszNetwork;
    AssertReturn(cchNetwork, VERR_INVALID_PARAMETER);

    if (pszTrunk)
    {
        AssertPtrReturn(pszTrunk, VERR_INVALID_PARAMETER);
        const char *pszTrunkEnd = (const char *)memchr(pszTrunk, '\0', INTNET_MAX_TRUNK_NAME);
        AssertReturn(pszTrunkEnd, VERR_INVALID_PARAMETER);
    }
    else
        pszTrunk = "";

    AssertMsgReturn(enmTrunkType > kIntNetTrunkType_Invalid && enmTrunkType < kIntNetTrunkType_End,
                    ("%d\n", enmTrunkType), VERR_INVALID_PARAMETER);
    switch (enmTrunkType)
    {
        case kIntNetTrunkType_None:
        case kIntNetTrunkType_WhateverNone:
            AssertReturn(!*pszTrunk, VERR_INVALID_PARAMETER);
            break;

        case kIntNetTrunkType_NetFlt:
            AssertReturn(pszTrunk, VERR_INVALID_PARAMETER);
            break;

        default:
            return VERR_NOT_IMPLEMENTED;
    }

    AssertMsgReturn(!(fFlags & ~INTNET_OPEN_FLAGS_MASK), ("%#x\n", fFlags), VERR_INVALID_PARAMETER);
    AssertPtrReturn(phIf, VERR_INVALID_PARAMETER);

    /*
     * Acquire the mutex to serialize open/create.
     */
    int rc = RTSemFastMutexRequest(pIntNet->FastMutex);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Try open / create the network and create an interface on it for the caller to use.
     *
     * Note that because of the destructors grabbing INTNET::FastMutex and us being required
     * to own this semaphore for the entire network opening / creation and interface creation
     * sequence, intnetR0CreateNetwork will have to defer the network cleanup to us on failure.
     */
    PINTNETNETWORK pNetwork = NULL;
    rc = intnetR0OpenNetwork(pIntNet, pSession, pszNetwork, enmTrunkType, pszTrunk, fFlags, &pNetwork);
    if (RT_SUCCESS(rc) || rc == VERR_NOT_FOUND)
    {
        bool fCloseNetwork = true;
        if (rc == VERR_NOT_FOUND)
            rc = intnetR0CreateNetwork(pIntNet, pSession, pszNetwork, enmTrunkType, pszTrunk, fFlags, &pNetwork);
        if (RT_SUCCESS(rc))
            rc = intnetR0NetworkCreateIf(pNetwork, pSession, cbSend, cbRecv, &fCloseNetwork, phIf);

        RTSemFastMutexRelease(pIntNet->FastMutex);

        if (RT_FAILURE(rc) && pNetwork && fCloseNetwork)
            intnetR0NetworkClose(pNetwork, pSession);
    }
    else
        RTSemFastMutexRelease(pIntNet->FastMutex);

    LogFlow(("INTNETR0Open: return %Rrc *phIf=%RX32\n", rc, *phIf));
    return rc;
}


/**
 * VMMR0 request wrapper for GMMR0MapUnmapChunk.
 *
 * @returns see GMMR0MapUnmapChunk.
 * @param   pIntNet         The internal networking instance.
 * @param   pSession        The session handle.
 * @param   pReq            The request packet.
 */
INTNETR0DECL(int) INTNETR0OpenReq(PINTNET pIntNet, PSUPDRVSESSION pSession, PINTNETOPENREQ pReq)
{
    if (RT_UNLIKELY(pReq->Hdr.cbReq != sizeof(*pReq)))
        return VERR_INVALID_PARAMETER;
    return INTNETR0Open(pIntNet, pSession, &pReq->szNetwork[0], pReq->enmTrunkType, pReq->szTrunk,
                        pReq->fFlags, pReq->cbSend, pReq->cbRecv, &pReq->hIf);
}


/**
 * Destroys an instance of the Ring-0 internal networking service.
 *
 * @param   pIntNet     Pointer to the instance data.
 */
INTNETR0DECL(void) INTNETR0Destroy(PINTNET pIntNet)
{
    LogFlow(("INTNETR0Destroy: pIntNet=%p\n", pIntNet));

    /*
     * Allow NULL pointers.
     */
    if (!pIntNet)
        return;
    AssertPtrReturnVoid(pIntNet);

    /*
     * There is not supposed to be any networks hanging around at this time.
     */
    Assert(pIntNet->pNetworks == NULL);
    if (pIntNet->FastMutex != NIL_RTSEMFASTMUTEX)
    {
        RTSemFastMutexDestroy(pIntNet->FastMutex);
        pIntNet->FastMutex = NIL_RTSEMFASTMUTEX;
    }
    if (pIntNet->IfHandles.Spinlock != NIL_RTSPINLOCK)
    {
        RTSpinlockDestroy(pIntNet->IfHandles.Spinlock);
        pIntNet->IfHandles.Spinlock = NIL_RTSPINLOCK;
    }

    RTMemFree(pIntNet);
}


/**
 * Create an instance of the Ring-0 internal networking service.
 *
 * @returns VBox status code.
 * @param   ppIntNet    Where to store the instance pointer.
 */
INTNETR0DECL(int) INTNETR0Create(PINTNET *ppIntNet)
{
    LogFlow(("INTNETR0Create: ppIntNet=%p\n", ppIntNet));
    int rc = VERR_NO_MEMORY;
    PINTNET pIntNet = (PINTNET)RTMemAllocZ(sizeof(*pIntNet));
    if (pIntNet)
    {
        //pIntNet->pNetworks              = NULL;
        //pIntNet->IfHandles.paEntries    = NULL;
        //pIntNet->IfHandles.cAllocated   = 0;
        pIntNet->IfHandles.iHead        = UINT32_MAX;
        pIntNet->IfHandles.iTail        = UINT32_MAX;

        rc = RTSemFastMutexCreate(&pIntNet->FastMutex);
        if (RT_SUCCESS(rc))
        {
            rc = RTSpinlockCreate(&pIntNet->IfHandles.Spinlock);
            if (RT_SUCCESS(rc))
            {
                *ppIntNet = pIntNet;
                LogFlow(("INTNETR0Create: returns VINF_SUCCESS *ppIntNet=%p\n", pIntNet));
                return VINF_SUCCESS;
            }
            RTSemFastMutexDestroy(pIntNet->FastMutex);
        }
        RTMemFree(pIntNet);
    }
    *ppIntNet = NULL;
    LogFlow(("INTNETR0Create: returns %Rrc\n", rc));
    return rc;
}