/*
 * COPYRIGHT:   See COPYING in the top level directory
 * PROJECT:     ReactOS TCP/IP protocol driver
 * FILE:        network/neighbor.c
 * PURPOSE:     Neighbor address cache
 * PROGRAMMERS: Casper S. Hornstrup (chorns@users.sourceforge.net)
 * REVISIONS:
 *   CSH 01/08-2000 Created
 */
#include <tcpip.h>
#include <neighbor.h>
#include <routines.h>
#include <neighbor.h>
#include <transmit.h>
#include <address.h>
#include <route.h>
#include <pool.h>
#include <arp.h>
#include <ip.h>


NEIGHBOR_CACHE_TABLE NeighborCache[NB_HASHMASK + 1];


VOID FreeNCE(
    PVOID Object)
{
    ExFreePool(Object);
}


VOID NCETimeout(
    PNEIGHBOR_CACHE_ENTRY NCE)
/*
 * FUNCTION: Neighbor cache entry timeout handler
 * NOTES:
 *     The neighbor cache lock must be held
 */
{
    PNDIS_PACKET NdisPacket, Next;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. NCE (0x%X).\n", NCE));

    TI_DbgPrint(DEBUG_NCACHE, ("NCE->State is (0x%X).\n", NCE->State));

    switch (NCE->State) {
    case NUD_INCOMPLETE:
        /* Retransmission timer expired */
        if (NCE->EventCount++ > MAX_MULTICAST_SOLICIT) {
            /* We have retransmitted too many times */

            /* Calling IPSendComplete with cache lock held is not
               a great thing to do. We don't get here very often
               so maybe it's not that big a problem */

            /* Flush packet queue */
            NdisPacket = NCE->WaitQueue;
            while (NdisPacket) {
                Next = (PNDIS_PACKET)PC(NdisPacket)->DLComplete;
                IPSendComplete((PVOID)NCE->Interface, NdisPacket,
                    NDIS_STATUS_REQUEST_ABORTED);
                NdisPacket = Next;
            }
            NCE->WaitQueue = NULL;

            NCE->EventCount = 0;

            /* Remove route cache entries with references to this NCE.
               Remember that neighbor cache lock is taken before
               route cache lock */
            RouteInvalidateNCE(NCE);
        } else
            /* Retransmit request */
            NBSendSolicit(NCE);
        break;

    case NUD_DELAY:
        /* FIXME: Delayed state */
        TI_DbgPrint(DEBUG_NCACHE, ("NCE delay state.\n"));
        break;

    case NUD_PROBE:
        /* FIXME: Probe state */
        TI_DbgPrint(DEBUG_NCACHE, ("NCE probe state.\n"));
        break;

    default:
        /* Should not happen since other states don't use the event timer */
        TI_DbgPrint(MIN_TRACE, ("Invalid NCE state (%d).\n", NCE->State));
        break;
    }
}


VOID NBTimeout(
    VOID)
/*
 * FUNCTION: Neighbor address cache timeout handler
 * NOTES:
 *     This routine is called by IPTimeout to remove outdated cache
 *     entries.
 */
{
    UINT i;
    KIRQL OldIrql;
    PNEIGHBOR_CACHE_ENTRY NCE;

    for (i = 0; i <= NB_HASHMASK; i++) {
        KeAcquireSpinLock(&NeighborCache[i].Lock, &OldIrql);

        for (NCE = NeighborCache[i].Cache;
            NCE != NULL; NCE = NCE->Next) {
            /* Check if event timer is running */
            if (NCE->EventTimer != 0)  {
                if (--NCE->EventTimer == 0) {
                    /* Call timeout handler for NCE */
                    NCETimeout(NCE);
                }
            }
        }

        KeReleaseSpinLock(&NeighborCache[i].Lock, OldIrql);
    }
}


VOID NBStartup(
    VOID)
/*
 * FUNCTION: Starts the neighbor cache
 */
{
	UINT i;

    TI_DbgPrint(DEBUG_NCACHE, ("Called.\n"));

    for (i = 0; i <= NB_HASHMASK; i++) {
        NeighborCache[i].Cache = NULL;
        KeInitializeSpinLock(&NeighborCache[i].Lock);
    }
}


VOID NBShutdown(
    VOID)
/*
 * FUNCTION: Shuts down the neighbor cache
 */
{
	UINT i;
    KIRQL OldIrql;
    PNDIS_PACKET NdisPacket, Next;
    PNEIGHBOR_CACHE_ENTRY CurNCE, NextNCE;

    TI_DbgPrint(DEBUG_NCACHE, ("Called.\n"));

    /* Remove possible entries from the cache */
    for (i = 0; i <= NB_HASHMASK; i++) {
        KeAcquireSpinLock(&NeighborCache[i].Lock, &OldIrql);

        CurNCE = NeighborCache[i].Cache;
        while (CurNCE) {
            NextNCE = CurNCE->Next;

            /* Remove all references from route cache */
            RouteInvalidateNCE(CurNCE);

            /* Flush wait queue */
            NdisPacket = CurNCE->WaitQueue;
            while (NdisPacket) {
                Next = (PNDIS_PACKET)PC(NdisPacket)->DLComplete;
                FreeNdisPacket(NdisPacket);
                NdisPacket = Next;
            }

#if DBG
            if (CurNCE->RefCount != 1) {
                TI_DbgPrint(DEBUG_REFCOUNT, ("NCE at (0x%X) has (%d) references (should be 1).\n", CurNCE, CurNCE->RefCount));
            }
#endif

            /* Remove reference for being alive */
            DereferenceObject(CurNCE);

            CurNCE = NextNCE;
        }
        NeighborCache[i].Cache = NULL;

        KeReleaseSpinLock(&NeighborCache[i].Lock, OldIrql);
    }

    TI_DbgPrint(MAX_TRACE, ("Leaving.\n"));
}


VOID NBSendSolicit(
    PNEIGHBOR_CACHE_ENTRY NCE)
/*
 * FUNCTION: Sends a neighbor solicitation message
 * ARGUMENTS:
 *     NCE = Pointer to NCE of neighbor to solicit
 * NOTES:
 *     May be called with lock held on NCE's table
 */
{
    PLIST_ENTRY CurrentEntry;
    PNET_TABLE_ENTRY NTE;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. NCE (0x%X).\n", NCE));

    if (NCE->State == NUD_INCOMPLETE) {
        /* This is the first solicitation of this neighbor. Broadcast
           a request for the neighbor */

        /* FIXME: Choose first NTE. We might want to give an NTE as argument */
        CurrentEntry = NCE->Interface->NTEListHead.Flink;
        if (!IsListEmpty(CurrentEntry)) {
            NTE = CONTAINING_RECORD(CurrentEntry, NET_TABLE_ENTRY, IFListEntry);
            ARPTransmit(NCE->Address, NTE);
        } else {
            TI_DbgPrint(MIN_TRACE, ("Interface at 0x%X has zero NTE.\n", NCE->Interface));
        }
    } else {
        /* FIXME: Unicast solicitation since we have a cached address */
        TI_DbgPrint(MIN_TRACE, ("Uninplemented unicast solicitation.\n"));
    }
}


PNEIGHBOR_CACHE_ENTRY NBAddNeighbor(
    PIP_INTERFACE Interface,
    PIP_ADDRESS Address,
    PVOID LinkAddress,
    UINT LinkAddressLength,
    UCHAR State)
/*
 * FUNCTION: Adds a neighbor to the neighbor cache
 * ARGUMENTS:
 *     Interface         = Pointer to interface
 *     Address           = Pointer to IP address
 *     LinkAddress       = Pointer to link address (may be NULL)
 *     LinkAddressLength = Length of link address
 *     State             = State of NCE
 * RETURNS:
 *     Pointer to NCE, NULL there is not enough free resources
 * NOTES:
 *     The NCE if referenced for the caller if created. The NCE retains
 *     a reference to the IP address if it is created, the caller is
 *     responsible for providing this reference
 */
{
    ULONG HashValue;
    KIRQL OldIrql;
    PNEIGHBOR_CACHE_ENTRY NCE;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. Interface (0x%X)  Address (0x%X)  "
        "LinkAddress (0x%X)  LinkAddressLength (%d)  State (0x%X)\n",
        Interface, Address, LinkAddress, LinkAddressLength, State));

    NCE = ExAllocatePool(NonPagedPool, sizeof(NEIGHBOR_CACHE_ENTRY) + LinkAddressLength);
    if (!NCE) {
        TI_DbgPrint(MIN_TRACE, ("Insufficient resources.\n"));
        return NULL;
    }

    INIT_TAG(NCE, TAG('N','C','E',' '));

    /* Initialize NCE free routine */
    NCE->Free = FreeNCE;

    /* Reference once for beeing alive and once for the caller */
    NCE->RefCount  = 2;
    NCE->Interface = Interface;
    NCE->Address   = Address;
    NCE->LinkAddressLength = LinkAddressLength;
    NCE->LinkAddress       = (PVOID)((ULONG_PTR)NCE + sizeof(NEIGHBOR_CACHE_ENTRY));
    if (LinkAddress)
        RtlCopyMemory(NCE->LinkAddress, LinkAddress, LinkAddressLength);
    NCE->State      = State;
    NCE->EventTimer = 0; /* Not in use */
    NCE->WaitQueue  = NULL;

    HashValue  = *(PULONG)&Address->Address;
    HashValue ^= HashValue >> 16;
    HashValue ^= HashValue >> 8;
    HashValue ^= HashValue >> 4;
    HashValue &= NB_HASHMASK;

    NCE->Table = &NeighborCache[HashValue];

    KeAcquireSpinLock(&NeighborCache[HashValue].Lock, &OldIrql);

    NCE->Next = NeighborCache[HashValue].Cache;
    NeighborCache[HashValue].Cache = NCE;

    KeReleaseSpinLock(&NeighborCache[HashValue].Lock, OldIrql);

    return NCE;
}


VOID NBUpdateNeighbor(
    PNEIGHBOR_CACHE_ENTRY NCE,
    PVOID LinkAddress,
    UCHAR State)
/*
 * FUNCTION: Update link address information in NCE
 * ARGUMENTS:
 *     NCE         = Pointer to NCE to update
 *     LinkAddress = Pointer to link address
 *     State       = State of NCE
 * NOTES:
 *     The link address and state is updated. Any waiting packets are sent
 */
{
    KIRQL OldIrql;
    PNDIS_PACKET Current;
    PNDIS_PACKET Next;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. NCE (0x%X)  LinkAddress (0x%X)  State (0x%X).\n", NCE, LinkAddress, State));

    KeAcquireSpinLock(&NCE->Table->Lock, &OldIrql);

    RtlCopyMemory(NCE->LinkAddress, LinkAddress, NCE->LinkAddressLength);
    NCE->State     = State;
    Current        = NCE->WaitQueue;
    NCE->WaitQueue = NULL;

    KeReleaseSpinLock(&NCE->Table->Lock, OldIrql);
#if 1
    /* Send any waiting packets */
    while (Current) {
        /* Our link to the next packet is broken by the
           datalink layer code so we must save it here */
        Next = (PNDIS_PACKET)PC(Current)->DLComplete;
        IPSendFragment(Current, NCE);
        Current = Next;
    }
#endif
}


PNEIGHBOR_CACHE_ENTRY NBLocateNeighbor(
    PIP_ADDRESS Address)
/*
 * FUNCTION: Locates a neighbor in the neighbor cache
 * ARGUMENTS:
 *     Address = Pointer to IP address
 * RETURNS:
 *     Pointer to NCE, NULL if not found
 * NOTES:
 *     If the NCE is found, it is referenced. The caller is
 *     responsible for dereferencing it again after use
 */
{
    UINT HashValue;
    KIRQL OldIrql;
    PNEIGHBOR_CACHE_ENTRY NCE;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. Address (0x%X).\n", Address));

    HashValue  = *(PULONG)&Address->Address;
    HashValue ^= HashValue >> 16;
    HashValue ^= HashValue >> 8;
    HashValue ^= HashValue >> 4;
    HashValue &= NB_HASHMASK;

    KeAcquireSpinLock(&NeighborCache[HashValue].Lock, &OldIrql);

    NCE = NeighborCache[HashValue].Cache;

    while ((NCE) && (!AddrIsEqual(Address, NCE->Address)))
        NCE = NCE->Next;

    if (NCE)
        ReferenceObject(NCE);

    KeReleaseSpinLock(&NeighborCache[HashValue].Lock, OldIrql);

    TI_DbgPrint(MAX_TRACE, ("Leaving.\n"));

    return NCE;
}


PNEIGHBOR_CACHE_ENTRY NBFindOrCreateNeighbor(
    PIP_INTERFACE Interface,
    PIP_ADDRESS Address)
/*
 * FUNCTION: Tries to find a neighbor and if unsuccesful, creates a new NCE
 * ARGUMENTS:
 *     Interface = Pointer to interface to use (if NCE is not found)
 *     Address   = Pointer to IP address
 * RETURNS:
 *     Pointer to NCE, NULL if there is not enough free resources
 * NOTES:
 *     The NCE is referenced if found or created. The caller is
 *     responsible for dereferencing it again after use
 */
{
    PNEIGHBOR_CACHE_ENTRY NCE;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. Interface (0x%X)  Address (0x%X).\n", Interface, Address));

    NCE = NBLocateNeighbor(Address);
    if (!NCE) {
        ReferenceObject(Address);
        NCE = NBAddNeighbor(Interface, Address, NULL, 
            Interface->AddressLength, NUD_INCOMPLETE);
        NCE->EventTimer = 1;
        NCE->EventCount = 0;
    }

    return NCE;
}


BOOLEAN NBQueuePacket(
    PNEIGHBOR_CACHE_ENTRY NCE,
    PNDIS_PACKET NdisPacket)
/*
 * FUNCTION: Queues a packet on an NCE for later transmission
 * ARGUMENTS:
 *     NCE        = Pointer to NCE to queue packet on
 *     NdisPacket = Pointer to NDIS packet to queue
 * RETURNS:
 *     TRUE if the packet was successfully queued, FALSE if not
 */
{
    KIRQL OldIrql;
    PKSPIN_LOCK Lock;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. NCE (0x%X)  NdisPacket (0x%X).\n", NCE, NdisPacket));

    /* FIXME: Should we limit the number of queued packets? */

    Lock = &NCE->Table->Lock;

    KeAcquireSpinLock(Lock, &OldIrql);

    /* Use data link level completion handler pointer to link
       queued packets together */
    PC(NdisPacket)->DLComplete = (PACKET_COMPLETION_ROUTINE)NCE->WaitQueue;
    NCE->WaitQueue = NdisPacket;

    KeReleaseSpinLock(Lock, OldIrql);

    return TRUE;
}


VOID NBRemoveNeighbor(
    PNEIGHBOR_CACHE_ENTRY NCE)
/*
 * FUNCTION: Removes a neighbor from the neighbor cache
 * ARGUMENTS:
 *     NCE = Pointer to NCE to remove from cache
 * NOTES:
 *     The NCE must be in a safe state
 */
{
    ULONG HashValue;
    KIRQL OldIrql;
    PNEIGHBOR_CACHE_ENTRY *PrevNCE;
    PNEIGHBOR_CACHE_ENTRY CurNCE;
    PNDIS_PACKET NdisPacket, Next;

    TI_DbgPrint(DEBUG_NCACHE, ("Called. NCE (0x%X).\n", NCE));

	  HashValue  = *(PULONG)(&NCE->Address->Address);
    HashValue ^= HashValue >> 16;
	  HashValue ^= HashValue >> 8;
	  HashValue ^= HashValue >> 4;
	  HashValue &= NB_HASHMASK;

    KeAcquireSpinLock(&NeighborCache[HashValue].Lock, &OldIrql);

    /* Search the list and remove the NCE from the list if found */
    for (PrevNCE = &NeighborCache[HashValue].Cache;
        (CurNCE  = *PrevNCE) != NULL;
        PrevNCE  = &CurNCE->Next) {
        if (CurNCE == NCE) {
            /* Found it, now unlink it from the list */
            *PrevNCE = CurNCE->Next;

            /* Purge wait queue */
            NdisPacket = CurNCE->WaitQueue;
            while (NdisPacket) {
                Next = (PNDIS_PACKET)PC(NdisPacket)->DLComplete;
                FreeNdisPacket(NdisPacket);
                NdisPacket = Next;
            }

            /* Remove all references from route cache */
            RouteInvalidateNCE(CurNCE);

            /* Remove reference to the address */
            DereferenceObject(CurNCE->Address);

#if DBG
            CurNCE->RefCount--;

            if (CurNCE->RefCount != 0) {
                TI_DbgPrint(DEBUG_REFCOUNT, ("NCE at (0x%X) has (%d) references (should be 0).\n", CurNCE, CurNCE->RefCount));
            }
#endif
            ExFreePool(CurNCE);

            KeReleaseSpinLock(&NeighborCache[HashValue].Lock, OldIrql);

            return;
        }
    }

    KeReleaseSpinLock(&NeighborCache[HashValue].Lock, OldIrql);
}

/* EOF */