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windows-nt/Source/XPSP1/NT/net/tcpip/tpipv6/tcpip6/tcp/tcprcv.c

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2020-09-26 03:20:57 -05:00
// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil -*- (for GNU Emacs)
//
// Copyright (c) 1985-2000 Microsoft Corporation
//
// This file is part of the Microsoft Research IPv6 Network Protocol Stack.
// You should have received a copy of the Microsoft End-User License Agreement
// for this software along with this release; see the file "license.txt".
// If not, please see http://www.research.microsoft.com/msripv6/license.htm,
// or write to Microsoft Research, One Microsoft Way, Redmond, WA 98052-6399.
//
// Abstract:
//
// TCP receive code.
//
// This file contains the code for handling incoming TCP packets.
//
#include "oscfg.h"
#include "ndis.h"
#include "ip6imp.h"
#include "ip6def.h"
#include "icmp.h"
#include "tdi.h"
#include "tdint.h"
#include "tdistat.h"
#include "queue.h"
#include "transprt.h"
#include "addr.h"
#include "tcp.h"
#include "tcb.h"
#include "tcpconn.h"
#include "tcpsend.h"
#include "tcprcv.h"
#include "tcpdeliv.h"
#include "info.h"
#include "tcpcfg.h"
#include "route.h"
#include "security.h"
uint RequestCompleteFlags;
Queue ConnRequestCompleteQ;
Queue SendCompleteQ;
Queue TCBDelayQ;
KSPIN_LOCK RequestCompleteLock;
KSPIN_LOCK TCBDelayLock;
ulong TCBDelayRtnCount;
ulong TCBDelayRtnLimit;
#define TCB_DELAY_RTN_LIMIT 4
uint MaxDupAcks = 2;
extern KSPIN_LOCK TCBTableLock;
extern KSPIN_LOCK AddrObjTableLock;
#define PERSIST_TIMEOUT MS_TO_TICKS(500)
void ResetSendNext(TCB *SeqTCB, SeqNum NewSeq);
NTSTATUS TCPPrepareIrpForCancel(PTCP_CONTEXT TcpContext, PIRP Irp,
PDRIVER_CANCEL CancelRoutine);
extern void TCPRequestComplete(void *Context, unsigned int Status,
unsigned int UnUsed);
VOID TCPCancelRequest(PDEVICE_OBJECT Device, PIRP Irp);
//
// All of the init code can be discarded.
//
#ifdef ALLOC_PRAGMA
int InitTCPRcv(void);
#pragma alloc_text(INIT, InitTCPRcv)
#endif // ALLOC_PRAGMA
//* AdjustRcvWin - Adjust the receive window on a TCB.
//
// A utility routine that adjusts the receive window to an even multiple of
// the local segment size. We round it up to the next closest multiple, or
// leave it alone if it's already an event multiple. We assume we have
// exclusive access to the input TCB.
//
void // Returns: Nothing.
AdjustRcvWin(
TCB *WinTCB) // TCB to be adjusted.
{
ushort LocalMSS;
uchar FoundMSS;
ulong SegmentsInWindow;
ASSERT(WinTCB->tcb_defaultwin != 0);
ASSERT(WinTCB->tcb_rcvwin != 0);
ASSERT(WinTCB->tcb_remmss != 0);
if (WinTCB->tcb_flags & WINDOW_SET)
return;
#if 0
//
// First, get the local MSS by calling IP.
//
// REVIEW: IPv4 had code here to call down to IP to get the local MTU
// REVIEW: corresponding to this source address. Result in "LocalMSS",
// REVIEW: status of call in "FoundMSS".
//
// REVIEW: Why did they do this? tcb_mss is already set by this point!
//
if (!FoundMSS) {
//
// Didn't find it, error out.
//
ASSERT(FALSE);
return;
}
LocalMSS -= sizeof(TCPHeader);
LocalMSS = MIN(LocalMSS, WinTCB->tcb_remmss);
#else
LocalMSS = WinTCB->tcb_mss;
#endif
SegmentsInWindow = WinTCB->tcb_defaultwin / (ulong)LocalMSS;
//
// Make sure we have at least 4 segments in window, if that wouldn't make
// the window too big.
//
if (SegmentsInWindow < 4) {
//
// We have fewer than four segments in the window. Round up to 4
// if we can do so without exceeding the maximum window size; otherwise
// use the maximum multiple that we can fit in 64K. The exception is
// if we can only fit one integral multiple in the window - in that
// case we'll use a window of 0xffff.
//
if (LocalMSS <= (0xffff/4)) {
WinTCB->tcb_defaultwin = (uint)(4 * LocalMSS);
} else {
ulong SegmentsInMaxWindow;
//
// Figure out the maximum number of segments we could possibly
// fit in a window. If this is > 1, use that as the basis for
// our window size. Otherwise use a maximum size window.
//
SegmentsInMaxWindow = 0xffff/(ulong)LocalMSS;
if (SegmentsInMaxWindow != 1)
WinTCB->tcb_defaultwin = SegmentsInMaxWindow * (ulong)LocalMSS;
else
WinTCB->tcb_defaultwin = 0xffff;
}
WinTCB->tcb_rcvwin = WinTCB->tcb_defaultwin;
} else {
//
// If it's not already an even multiple, bump the default and current
// windows to the nearest multiple.
//
if ((SegmentsInWindow * (ulong)LocalMSS) != WinTCB->tcb_defaultwin) {
ulong NewWindow;
NewWindow = (SegmentsInWindow + 1) * (ulong)LocalMSS;
// Don't let the new window be > 64K.
if (NewWindow <= 0xffff) {
WinTCB->tcb_defaultwin = (uint)NewWindow;
WinTCB->tcb_rcvwin = (uint)NewWindow;
}
}
}
}
//* CompleteRcvs - Complete receives on a TCB.
//
// Called when we need to complete receives on a TCB. We'll pull things from
// the TCB's receive queue, as long as there are receives that have the PUSH
// bit set.
//
void // Returns: Nothing.
CompleteRcvs(
TCB *CmpltTCB) // TCB to complete on.
{
KIRQL OldIrql;
TCPRcvReq *CurrReq, *NextReq, *IndReq;
CHECK_STRUCT(CmpltTCB, tcb);
ASSERT(CmpltTCB->tcb_refcnt != 0);
KeAcquireSpinLock(&CmpltTCB->tcb_lock, &OldIrql);
if (!CLOSING(CmpltTCB) && !(CmpltTCB->tcb_flags & RCV_CMPLTING)
&& (CmpltTCB->tcb_rcvhead != NULL)) {
CmpltTCB->tcb_flags |= RCV_CMPLTING;
for (;;) {
CurrReq = CmpltTCB->tcb_rcvhead;
IndReq = NULL;
do {
CHECK_STRUCT(CurrReq, trr);
if (CurrReq->trr_flags & TRR_PUSHED) {
//
// Need to complete this one. If this is the current
// receive then advance the current receive to the next
// one in the list. Then set the list head to the next
// one in the list.
//
ASSERT(CurrReq->trr_amt != 0 ||
!DATA_RCV_STATE(CmpltTCB->tcb_state));
NextReq = CurrReq->trr_next;
if (CmpltTCB->tcb_currcv == CurrReq)
CmpltTCB->tcb_currcv = NextReq;
CmpltTCB->tcb_rcvhead = NextReq;
if (NextReq == NULL) {
//
// We've just removed the last buffer. Set the
// rcvhandler to PendData, in case something
// comes in during the callback.
//
ASSERT(CmpltTCB->tcb_rcvhndlr != IndicateData);
CmpltTCB->tcb_rcvhndlr = PendData;
}
KeReleaseSpinLock(&CmpltTCB->tcb_lock, OldIrql);
if (CurrReq->trr_uflags != NULL)
*(CurrReq->trr_uflags) =
TDI_RECEIVE_NORMAL | TDI_RECEIVE_ENTIRE_MESSAGE;
(*CurrReq->trr_rtn)(CurrReq->trr_context, TDI_SUCCESS,
CurrReq->trr_amt);
if (IndReq != NULL)
FreeRcvReq(CurrReq);
else
IndReq = CurrReq;
KeAcquireSpinLock(&CmpltTCB->tcb_lock, &OldIrql);
CurrReq = CmpltTCB->tcb_rcvhead;
} else
// This one isn't to be completed, so bail out.
break;
} while (CurrReq != NULL);
//
// Now see if we've completed all of the requests. If we have,
// we may need to deal with pending data and/or reset the receive
// handler.
//
if (CurrReq == NULL) {
//
// We've completed everything that can be, so stop the push
// timer. We don't stop it if CurrReq isn't NULL because we
// want to make sure later data is eventually pushed.
//
STOP_TCB_TIMER(CmpltTCB->tcb_pushtimer);
ASSERT(IndReq != NULL);
//
// No more receive requests.
//
if (CmpltTCB->tcb_pendhead == NULL) {
FreeRcvReq(IndReq);
//
// No pending data. Set the receive handler to either
// PendData or IndicateData.
//
if (!(CmpltTCB->tcb_flags & (DISC_PENDING | GC_PENDING))) {
if (CmpltTCB->tcb_rcvind != NULL &&
CmpltTCB->tcb_indicated == 0)
CmpltTCB->tcb_rcvhndlr = IndicateData;
else
CmpltTCB->tcb_rcvhndlr = PendData;
} else {
goto Complete_Notify;
}
} else {
//
// We have pending data to deal with.
//
if (CmpltTCB->tcb_rcvind != NULL &&
CmpltTCB->tcb_indicated == 0) {
//
// There's a receive indicate handler on this TCB.
// Call the indicate handler with the pending data.
//
IndicatePendingData(CmpltTCB, IndReq, OldIrql);
SendACK(CmpltTCB);
KeAcquireSpinLock(&CmpltTCB->tcb_lock, &OldIrql);
//
// See if a buffer has been posted. If so, we'll need
// to check and see if it needs to be completed.
//
if (CmpltTCB->tcb_rcvhead != NULL)
continue;
else {
//
// If the pending head is now NULL, we've used up
// all the data.
//
if (CmpltTCB->tcb_pendhead == NULL &&
(CmpltTCB->tcb_flags &
(DISC_PENDING | GC_PENDING)))
goto Complete_Notify;
}
} else {
//
// No indicate handler, so nothing to do. The receive
// handler should already be set to PendData.
//
FreeRcvReq(IndReq);
ASSERT(CmpltTCB->tcb_rcvhndlr == PendData);
}
}
} else {
if (IndReq != NULL)
FreeRcvReq(IndReq);
ASSERT(CmpltTCB->tcb_rcvhndlr == BufferData);
}
break;
}
CmpltTCB->tcb_flags &= ~RCV_CMPLTING;
}
KeReleaseSpinLock(&CmpltTCB->tcb_lock, OldIrql);
return;
Complete_Notify:
//
// Something is pending. Figure out what it is, and do it.
//
if (CmpltTCB->tcb_flags & GC_PENDING) {
CmpltTCB->tcb_flags &= ~RCV_CMPLTING;
//
// Bump the refcnt, because GracefulClose will deref the TCB
// and we're not really done with it yet.
//
CmpltTCB->tcb_refcnt++;
GracefulClose(CmpltTCB, CmpltTCB->tcb_flags & TW_PENDING, TRUE,
OldIrql);
} else
if (CmpltTCB->tcb_flags & DISC_PENDING) {
CmpltTCB->tcb_flags &= ~DISC_PENDING;
KeReleaseSpinLock(&CmpltTCB->tcb_lock, OldIrql);
NotifyOfDisc(CmpltTCB, TDI_GRACEFUL_DISC);
KeAcquireSpinLock(&CmpltTCB->tcb_lock, &OldIrql);
CmpltTCB->tcb_flags &= ~RCV_CMPLTING;
KeReleaseSpinLock(&CmpltTCB->tcb_lock, OldIrql);
} else {
ASSERT(FALSE);
KeReleaseSpinLock(&CmpltTCB->tcb_lock, OldIrql);
}
return;
}
//* ProcessTCBDelayQ - Process TCBs on the delayed Q.
//
// Called at various times to process TCBs on the delayed Q.
//
void // Returns: Nothing.
ProcessTCBDelayQ(
void) // Nothing.
{
KIRQL OldIrql;
TCB *DelayTCB;
KeAcquireSpinLock(&TCBDelayLock, &OldIrql);
//
// Check for recursion. We do not stop recursion completely, only
// limit it. This is done to allow multiple threads to process the
// TCBDelayQ simultaneously.
//
TCBDelayRtnCount++;
if (TCBDelayRtnCount > TCBDelayRtnLimit) {
TCBDelayRtnCount--;
KeReleaseSpinLock(&TCBDelayLock, OldIrql);
return;
}
while (!EMPTYQ(&TCBDelayQ)) {
DEQUEUE(&TCBDelayQ, DelayTCB, TCB, tcb_delayq);
CHECK_STRUCT(DelayTCB, tcb);
ASSERT(DelayTCB->tcb_refcnt != 0);
ASSERT(DelayTCB->tcb_flags & IN_DELAY_Q);
KeReleaseSpinLock(&TCBDelayLock, OldIrql);
KeAcquireSpinLock(&DelayTCB->tcb_lock, &OldIrql);
while (!CLOSING(DelayTCB) && (DelayTCB->tcb_flags & DELAYED_FLAGS)) {
if (DelayTCB->tcb_flags & NEED_RCV_CMPLT) {
DelayTCB->tcb_flags &= ~NEED_RCV_CMPLT;
KeReleaseSpinLock(&DelayTCB->tcb_lock, OldIrql);
CompleteRcvs(DelayTCB);
KeAcquireSpinLock(&DelayTCB->tcb_lock, &OldIrql);
}
if (DelayTCB->tcb_flags & NEED_OUTPUT) {
DelayTCB->tcb_flags &= ~NEED_OUTPUT;
DelayTCB->tcb_refcnt++;
TCPSend(DelayTCB, OldIrql);
KeAcquireSpinLock(&DelayTCB->tcb_lock, &OldIrql);
}
if (DelayTCB->tcb_flags & NEED_ACK) {
DelayTCB->tcb_flags &= ~NEED_ACK;
KeReleaseSpinLock(&DelayTCB->tcb_lock, OldIrql);
SendACK(DelayTCB);
KeAcquireSpinLock(&DelayTCB->tcb_lock, &OldIrql);
}
}
DelayTCB->tcb_flags &= ~IN_DELAY_Q;
DerefTCB(DelayTCB, OldIrql);
KeAcquireSpinLock(&TCBDelayLock, &OldIrql);
}
TCBDelayRtnCount--;
KeReleaseSpinLock(&TCBDelayLock, OldIrql);
}
//* DelayAction - Put a TCB on the queue for a delayed action.
//
// Called when we want to put a TCB on the DelayQ for a delayed action at
// receive complete or some other time. The lock on the TCB must be held
// when this is called.
//
void // Returns: Nothing.
DelayAction(
TCB *DelayTCB, // TCP which we're going to schedule.
uint Action) // Action we're scheduling.
{
//
// Schedule the completion.
//
KeAcquireSpinLockAtDpcLevel(&TCBDelayLock);
DelayTCB->tcb_flags |= Action;
if (!(DelayTCB->tcb_flags & IN_DELAY_Q)) {
DelayTCB->tcb_flags |= IN_DELAY_Q;
DelayTCB->tcb_refcnt++; // Reference this for later.
ENQUEUE(&TCBDelayQ, &DelayTCB->tcb_delayq);
}
KeReleaseSpinLockFromDpcLevel(&TCBDelayLock);
}
//* TCPRcvComplete - Handle a receive complete.
//
// Called by the lower layers when we're done receiving. We look to see
// if we have and pending requests to complete. If we do, we complete them.
// Then we look to see if we have any TCBs pending for output. If we do,
// we get them going.
//
void // Returns: Nothing.
TCPRcvComplete(
void) // Nothing.
{
KIRQL OldIrql;
TCPReq *Req;
if (RequestCompleteFlags & ANY_REQUEST_COMPLETE) {
KeAcquireSpinLock(&RequestCompleteLock, &OldIrql);
if (!(RequestCompleteFlags & IN_RCV_COMPLETE)) {
RequestCompleteFlags |= IN_RCV_COMPLETE;
do {
if (RequestCompleteFlags & CONN_REQUEST_COMPLETE) {
if (!EMPTYQ(&ConnRequestCompleteQ)) {
DEQUEUE(&ConnRequestCompleteQ, Req, TCPReq, tr_q);
CHECK_STRUCT(Req, tr);
CHECK_STRUCT(*(TCPConnReq **)&Req, tcr);
KeReleaseSpinLock(&RequestCompleteLock, OldIrql);
(*Req->tr_rtn)(Req->tr_context, Req->tr_status, 0);
FreeConnReq((TCPConnReq *)Req);
KeAcquireSpinLock(&RequestCompleteLock, &OldIrql);
} else
RequestCompleteFlags &= ~CONN_REQUEST_COMPLETE;
}
if (RequestCompleteFlags & SEND_REQUEST_COMPLETE) {
if (!EMPTYQ(&SendCompleteQ)) {
TCPSendReq *SendReq;
DEQUEUE(&SendCompleteQ, Req, TCPReq, tr_q);
CHECK_STRUCT(Req, tr);
SendReq = (TCPSendReq *)Req;
CHECK_STRUCT(SendReq, tsr);
KeReleaseSpinLock(&RequestCompleteLock, OldIrql);
(*Req->tr_rtn)(Req->tr_context, Req->tr_status,
Req->tr_status == TDI_SUCCESS ? SendReq->tsr_size
: 0);
FreeSendReq((TCPSendReq *)Req);
KeAcquireSpinLock(&RequestCompleteLock, &OldIrql);
} else
RequestCompleteFlags &= ~SEND_REQUEST_COMPLETE;
}
} while (RequestCompleteFlags & ANY_REQUEST_COMPLETE);
RequestCompleteFlags &= ~IN_RCV_COMPLETE;
}
KeReleaseSpinLock(&RequestCompleteLock, OldIrql);
}
ProcessTCBDelayQ();
}
//* CompleteConnReq - Complete a connection request on a TCB.
//
// A utility function to complete a connection request on a TCB. We remove
// the connreq, and put it on the ConnReqCmpltQ where it will be picked
// off later during RcvCmplt processing. We assume the TCB lock is held when
// we're called.
//
void // Returns: Nothing.
CompleteConnReq(
TCB *CmpltTCB, // TCB from which to complete.
TDI_STATUS Status) // Status to complete with.
{
TCPConnReq *ConnReq;
CHECK_STRUCT(CmpltTCB, tcb);
ConnReq = CmpltTCB->tcb_connreq;
if (ConnReq != NULL) {
//
// There's a connreq on this TCB. Fill in the connection information
// before returning it.
//
CmpltTCB->tcb_connreq = NULL;
UpdateConnInfo(ConnReq->tcr_conninfo, &CmpltTCB->tcb_daddr,
CmpltTCB->tcb_dscope_id, CmpltTCB->tcb_dport);
if (ConnReq->tcr_addrinfo) {
UpdateConnInfo(ConnReq->tcr_addrinfo, &CmpltTCB->tcb_saddr,
CmpltTCB->tcb_sscope_id, CmpltTCB->tcb_sport);
}
ConnReq->tcr_req.tr_status = Status;
KeAcquireSpinLockAtDpcLevel(&RequestCompleteLock);
RequestCompleteFlags |= CONN_REQUEST_COMPLETE;
ENQUEUE(&ConnRequestCompleteQ, &ConnReq->tcr_req.tr_q);
KeReleaseSpinLockFromDpcLevel(&RequestCompleteLock);
} else if (!((CmpltTCB->tcb_state == TCB_SYN_RCVD) &&
(CmpltTCB->tcb_flags & ACCEPT_PENDING))) {
//
// This should not happen except
// in the case of SynAttackProtect.
//
ASSERT(FALSE);
}
}
//* DelayedAcceptConn - Process delayed-connect request.
//
// Called by TCPRcv when SynAttackProtection is turned on, when a final
// ACK arrives in response to our SYN-ACK. Indicate the connect request to
// ULP and if it is accepted init TCB and move con to appropriate queue on AO.
// The caller must hold the AddrObjTableLock before calling this routine,
// and that lock must have been taken at DPC level. This routine will free
// that lock back to DPC level.
// Returns TRUE if the request is accepted.
//
BOOLEAN
DelayedAcceptConn(
AddrObj *ListenAO, // AddrObj for local address.
IPv6Addr *Src, // Source IP address of SYN.
ulong SrcScopeId, // Scope id of source address (0 for non-scope addr).
ushort SrcPort, // Source port of SYN.
TCB *AcceptTCB) // Pre-accepted TCB
{
TCPConn *CurrentConn = NULL;
Queue *Temp;
TCPConnReq *ConnReq = NULL;
BOOLEAN FoundConn = FALSE;
CHECK_STRUCT(ListenAO, ao);
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
KeReleaseSpinLockFromDpcLevel(&AddrObjTableLock);
if (AO_VALID(ListenAO)) {
if (ListenAO->ao_connect != NULL) {
uchar TAddress[TCP_TA_SIZE];
PVOID ConnContext;
PConnectEvent Event;
PVOID EventContext;
TDI_STATUS Status;
PTCP_CONTEXT TcpContext = NULL;
ConnectEventInfo *EventInfo;
// He has a connect handler. Put the transport address together,
// and call him. We also need to get the necessary resources
// first.
Event = ListenAO->ao_connect;
EventContext = ListenAO->ao_conncontext;
REF_AO(ListenAO);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
ConnReq = GetConnReq();
if (AcceptTCB != NULL && ConnReq != NULL) {
BuildTDIAddress(TAddress, Src, SrcScopeId, SrcPort);
IF_TCPDBG(TCP_DEBUG_CONNECT) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"indicating connect request\n"));
}
Status = (*Event) (EventContext, TCP_TA_SIZE,
(PTRANSPORT_ADDRESS) TAddress, 0, NULL,
0, NULL,
&ConnContext, &EventInfo);
if (Status == TDI_MORE_PROCESSING) {
PIO_STACK_LOCATION IrpSp;
PTDI_REQUEST_KERNEL_ACCEPT AcceptRequest;
IrpSp = IoGetCurrentIrpStackLocation(EventInfo);
Status = TCPPrepareIrpForCancel(
(PTCP_CONTEXT) IrpSp->FileObject->FsContext,
EventInfo,
TCPCancelRequest
);
if (!NT_SUCCESS(Status)) {
Status = TDI_NOT_ACCEPTED;
EventInfo = NULL;
goto AcceptIrpCancelled;
}
//
// He accepted it. Find the connection on the AddrObj.
//
IF_TCPDBG(TCP_DEBUG_CONNECT) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"connect indication accepted, queueing request\n"
));
}
AcceptRequest = (PTDI_REQUEST_KERNEL_ACCEPT)
& (IrpSp->Parameters);
ConnReq->tcr_conninfo =
AcceptRequest->ReturnConnectionInformation;
if (AcceptRequest->RequestConnectionInformation &&
AcceptRequest->RequestConnectionInformation->
RemoteAddress) {
ConnReq->tcr_addrinfo =
AcceptRequest->RequestConnectionInformation;
} else {
ConnReq->tcr_addrinfo = NULL;
}
ConnReq->tcr_req.tr_rtn = TCPRequestComplete;
ConnReq->tcr_req.tr_context = EventInfo;
AcceptTCB->tcb_connreq = ConnReq;
SearchAO:
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
Temp = QHEAD(&ListenAO->ao_idleq);;
Status = TDI_INVALID_CONNECTION;
while (Temp != QEND(&ListenAO->ao_idleq)) {
CurrentConn = QSTRUCT(TCPConn, Temp, tc_q);
CHECK_STRUCT(CurrentConn, tc);
if ((CurrentConn->tc_context == ConnContext) &&
!(CurrentConn->tc_flags & CONN_INVALID)) {
//
// We need to lock its TCPConnBlock, with care.
// We'll ref the TCPConn so it can't go away,
// then unlock the AO (which is already ref'd),
// then relock. Note that tc_refcnt is updated
// under ao_lock for any associated TCPConn.
// If things have changed, go back and try again.
//
++CurrentConn->tc_refcnt;
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
KeAcquireSpinLockAtDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
//
// Now that we've got the lock, we need to consider
// the following possibilities:
//
// * a disassociate was initiated
// * a close was initiated
// * accept completed
// * listen completed
// * connect completed
//
// The first two require that we clean up,
// by calling the tc_donertn. For the last three,
// we have nothing to do, but tc_donertn points at
// DummyDone, so go ahead and call it anyway;
// it'll release the TCPConnBlock lock for us.
//
if (--CurrentConn->tc_refcnt == 0 &&
((CurrentConn->tc_flags & CONN_INVALID) ||
(CurrentConn->tc_tcb != NULL))) {
ConnDoneRtn DoneRtn = CurrentConn->tc_donertn;
DoneRtn(CurrentConn, DISPATCH_LEVEL);
goto SearchAO;
}
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
// We think we have a match. The connection
// shouldn't have a TCB associated with it. If it
// does, it's an error. InitTCBFromConn will
// handle all this.
Status = InitTCBFromConn(CurrentConn,
AcceptTCB,
AcceptRequest->RequestConnectionInformation,
TRUE);
if (Status == TDI_SUCCESS) {
FoundConn = TRUE;
KeAcquireSpinLockAtDpcLevel(&AcceptTCB->tcb_lock);
AcceptTCB->tcb_conn = CurrentConn;
CurrentConn->tc_tcb = AcceptTCB;
KeReleaseSpinLockFromDpcLevel(&AcceptTCB->tcb_lock);
CurrentConn->tc_refcnt++;
// Move him from the idle q to the active
// queue.
REMOVEQ(&CurrentConn->tc_q);
ENQUEUE(&ListenAO->ao_activeq,
&CurrentConn->tc_q);
} else
KeReleaseSpinLockFromDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
// In any case, we're done now.
break;
}
Temp = QNEXT(Temp);
}
if (!FoundConn) {
CompleteConnReq(AcceptTCB, Status);
}
LOCKED_DELAY_DEREF_AO(ListenAO);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
if (FoundConn) {
KeReleaseSpinLockFromDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
}
return FoundConn;
}
//
// The event handler didn't take it. Dereference it, free
// the resources, and return NULL.
//
}
AcceptIrpCancelled:
//
// We couldn't get a valid tcb or getconnreq
//
if (ConnReq) {
FreeConnReq(ConnReq);
}
DELAY_DEREF_AO(ListenAO);
return FALSE;
} // ao_connect != null
} // AO not valid
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
return FALSE;
}
//* FindListenConn - Find (or fabricate) a listening connection.
//
// Called by our Receive handler to decide what to do about an incoming
// SYN. We walk down the list of connections associated with the destination
// address, and if we find any in the listening state that can be used for
// the incoming request we'll take them, possibly returning a listen in the
// process. If we don't find any appropriate listening connections, we'll
// call the Connect Event handler if one is registered. If all else fails,
// we'll return NULL and the SYN will be RST.
//
// The caller must hold the AddrObjTableLock before calling this routine,
// and that lock must have been taken at DPC level. This routine will free
// that lock back to DPC level.
//
TCB * // Returns: Pointer to found TCB, or NULL if we can't find one.
FindListenConn(
AddrObj *ListenAO, // AddrObj for local address.
IPv6Addr *Src, // Source IP address of SYN.
ulong SrcScopeId, // Scope id of source address (0 for non-scope addr).
ushort SrcPort) // Source port of SYN.
{
TCB *CurrentTCB = NULL;
TCPConn *CurrentConn = NULL;
TCPConnReq *ConnReq = NULL;
Queue *Temp;
uint FoundConn = FALSE;
CHECK_STRUCT(ListenAO, ao);
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
KeReleaseSpinLockFromDpcLevel(&AddrObjTableLock);
//
// We have the lock on the AddrObj. Walk down its list, looking
// for connections in the listening state.
//
if (AO_VALID(ListenAO)) {
if (ListenAO->ao_listencnt != 0) {
Temp = QHEAD(&ListenAO->ao_listenq);
while (Temp != QEND(&ListenAO->ao_listenq)) {
CurrentConn = QSTRUCT(TCPConn, Temp, tc_q);
CHECK_STRUCT(CurrentConn, tc);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
KeAcquireSpinLockAtDpcLevel(&CurrentConn->tc_ConnBlock->cb_lock);
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
//
// If this TCB is in the listening state, with no delete
// pending, it's a candidate. Look at the pending listen
// information to see if we should take it.
//
if ((CurrentTCB = CurrentConn->tc_tcb) != NULL &&
CurrentTCB->tcb_state == TCB_LISTEN) {
CHECK_STRUCT(CurrentTCB, tcb);
KeAcquireSpinLockAtDpcLevel(&CurrentTCB->tcb_lock);
if (CurrentTCB->tcb_state == TCB_LISTEN &&
!PENDING_ACTION(CurrentTCB)) {
//
// Need to see if we can take it.
// See if the addresses specifed in the ConnReq match.
//
if ((IsUnspecified(&CurrentTCB->tcb_daddr) ||
(IP6_ADDR_EQUAL(&CurrentTCB->tcb_daddr, Src) &&
(CurrentTCB->tcb_dscope_id == SrcScopeId))) &&
(CurrentTCB->tcb_dport == 0 ||
CurrentTCB->tcb_dport == SrcPort)) {
FoundConn = TRUE;
break;
}
//
// Otherwise, this didn't match, so we'll check the
// next one.
//
}
KeReleaseSpinLockFromDpcLevel(&CurrentTCB->tcb_lock);
}
KeReleaseSpinLockFromDpcLevel(&CurrentConn->tc_ConnBlock->cb_lock);
Temp = QNEXT(Temp);;
}
//
// See why we've exited the loop.
//
if (FoundConn) {
CHECK_STRUCT(CurrentTCB, tcb);
//
// We exited because we found a TCB. If it's pre-accepted,
// we're done.
//
CurrentTCB->tcb_refcnt++;
ASSERT(CurrentTCB->tcb_connreq != NULL);
ConnReq = CurrentTCB->tcb_connreq;
//
// If QUERY_ACCEPT isn't set, turn on the CONN_ACCEPTED bit.
//
if (!(ConnReq->tcr_flags & TDI_QUERY_ACCEPT))
CurrentTCB->tcb_flags |= CONN_ACCEPTED;
CurrentTCB->tcb_state = TCB_SYN_RCVD;
CurrentTCB->tcb_hops = ListenAO->ao_ucast_hops;
ListenAO->ao_listencnt--;
//
// Since he's no longer listening, remove him from the listen
// queue and put him on the active queue.
//
REMOVEQ(&CurrentConn->tc_q);
ENQUEUE(&ListenAO->ao_activeq, &CurrentConn->tc_q);
KeReleaseSpinLockFromDpcLevel(&CurrentTCB->tcb_lock);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
KeReleaseSpinLockFromDpcLevel(&CurrentConn->tc_ConnBlock->cb_lock);
return CurrentTCB;
}
}
//
// We didn't find a matching TCB.
//
ASSERT(FoundConn == FALSE);
if (SynAttackProtect) {
TCB *AcceptTCB = NULL;
//
// No need to hold ao_lock any more.
//
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
//
// SynAttack protection is on. Just initialize
// this TCB and send SYN-ACK. When final
// ACK is seen we will indicate about this
// connection arrival to upper layer.
//
AcceptTCB = AllocTCB();
if (AcceptTCB) {
AcceptTCB->tcb_state = TCB_SYN_RCVD;
AcceptTCB->tcb_connreq = NULL;
AcceptTCB->tcb_flags |= CONN_ACCEPTED;
AcceptTCB->tcb_flags |= ACCEPT_PENDING;
AcceptTCB->tcb_refcnt = 1;
AcceptTCB->tcb_defaultwin = DEFAULT_RCV_WIN;
AcceptTCB->tcb_rcvwin = DEFAULT_RCV_WIN;
IF_TCPDBG(TCP_DEBUG_CONNECT) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"Allocated SP TCB %x\n", (PCHAR)AcceptTCB));
}
}
return AcceptTCB;
}
//
// If there's a connect indication
// handler, call it now to find a connection to accept on.
//
if (ListenAO->ao_connect != NULL) {
uchar TAddress[TCP_TA_SIZE];
PVOID ConnContext;
PConnectEvent Event;
PVOID EventContext;
TDI_STATUS Status;
TCB *AcceptTCB;
ConnectEventInfo *EventInfo;
//
// He has a connect handler. Put the transport address together,
// and call him. We also need to get the necessary resources
// first.
//
Event = ListenAO->ao_connect;
EventContext = ListenAO->ao_conncontext;
REF_AO(ListenAO);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
AcceptTCB = AllocTCB();
ConnReq = GetConnReq();
if (AcceptTCB != NULL && ConnReq != NULL) {
BuildTDIAddress(TAddress, Src, SrcScopeId, SrcPort);
AcceptTCB->tcb_state = TCB_LISTEN;
AcceptTCB->tcb_connreq = ConnReq;
AcceptTCB->tcb_flags |= CONN_ACCEPTED;
IF_TCPDBG(TCP_DEBUG_CONNECT) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"indicating connect request\n"));
}
Status = (*Event)(EventContext, TCP_TA_SIZE,
(PTRANSPORT_ADDRESS)TAddress, 0, NULL,
0, NULL,
&ConnContext, &EventInfo);
if (Status == TDI_MORE_PROCESSING) {
PIO_STACK_LOCATION IrpSp;
PTDI_REQUEST_KERNEL_ACCEPT AcceptRequest;
IrpSp = IoGetCurrentIrpStackLocation(EventInfo);
Status = TCPPrepareIrpForCancel(
(PTCP_CONTEXT) IrpSp->FileObject->FsContext,
EventInfo, TCPCancelRequest);
if (!NT_SUCCESS(Status)) {
Status = TDI_NOT_ACCEPTED;
EventInfo = NULL;
goto AcceptIrpCancelled;
}
//
// He accepted it. Find the connection on the AddrObj.
//
{
IF_TCPDBG(TCP_DEBUG_CONNECT) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"connect indication accepted,"
" queueing request\n"));
}
AcceptRequest = (PTDI_REQUEST_KERNEL_ACCEPT)
&(IrpSp->Parameters);
ConnReq->tcr_conninfo =
AcceptRequest->ReturnConnectionInformation;
if (AcceptRequest->RequestConnectionInformation &&
AcceptRequest->RequestConnectionInformation->
RemoteAddress) {
ConnReq->tcr_addrinfo =
AcceptRequest->RequestConnectionInformation;
} else {
ConnReq->tcr_addrinfo = NULL;
}
ConnReq->tcr_req.tr_rtn = TCPRequestComplete;
ConnReq->tcr_req.tr_context = EventInfo;
}
SearchAO:
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
Temp = QHEAD(&ListenAO->ao_idleq);
CurrentTCB = NULL;
Status = TDI_INVALID_CONNECTION;
while (Temp != QEND(&ListenAO->ao_idleq)) {
CurrentConn = QSTRUCT(TCPConn, Temp, tc_q);
CHECK_STRUCT(CurrentConn, tc);
if ((CurrentConn->tc_context == ConnContext) &&
!(CurrentConn->tc_flags & CONN_INVALID)) {
//
// We need to lock its TCPConnBlock, with care.
// We'll ref the TCPConn so it can't go away,
// then unlock the AO (which is already ref'd),
// then relock. Note that tc_refcnt is updated
// under ao_lock for any associated TCPConn.
// If things have changed, go back and try again.
//
++CurrentConn->tc_refcnt;
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
KeAcquireSpinLockAtDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
//
// Now that we've got the lock, we need to consider
// the following possibilities:
//
// * a disassociate was initiated
// * a close was initiated
// * accept completed
// * listen completed
// * connect completed
//
// The first two require that we clean up,
// by calling the tc_donertn. For the last three,
// we have nothing to do, but tc_donertn points at
// DummyDone, so go ahead and call it anyway;
// it'll release the TCPConnBlock lock for us.
//
if (--CurrentConn->tc_refcnt == 0 &&
((CurrentConn->tc_flags & CONN_INVALID) ||
(CurrentConn->tc_tcb != NULL))) {
ConnDoneRtn DoneRtn = CurrentConn->tc_donertn;
DoneRtn(CurrentConn, DISPATCH_LEVEL);
goto SearchAO;
}
KeAcquireSpinLockAtDpcLevel(&ListenAO->ao_lock);
//
// We think we have a match. The connection
// shouldn't have a TCB associated with it. If it
// does, it's an error. InitTCBFromConn will
// handle all this.
//
AcceptTCB->tcb_refcnt = 1;
Status = InitTCBFromConn(CurrentConn, AcceptTCB,
AcceptRequest->RequestConnectionInformation,
TRUE);
if (Status == TDI_SUCCESS) {
FoundConn = TRUE;
AcceptTCB->tcb_state = TCB_SYN_RCVD;
AcceptTCB->tcb_conn = CurrentConn;
AcceptTCB->tcb_connid = CurrentConn->tc_connid;
CurrentConn->tc_tcb = AcceptTCB;
CurrentConn->tc_refcnt++;
//
// Move him from the idle queue to the
// active queue.
//
REMOVEQ(&CurrentConn->tc_q);
ENQUEUE(&ListenAO->ao_activeq,
&CurrentConn->tc_q);
} else
KeReleaseSpinLockFromDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
// In any case, we're done now.
break;
}
Temp = QNEXT(Temp);
}
if (!FoundConn) {
//
// Didn't find a match, or had an error.
// Status code is set.
// Complete the ConnReq and free the resources.
//
CompleteConnReq(AcceptTCB, Status);
FreeTCB(AcceptTCB);
AcceptTCB = NULL;
}
LOCKED_DELAY_DEREF_AO(ListenAO);
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
if (FoundConn) {
KeReleaseSpinLockFromDpcLevel(
&CurrentConn->tc_ConnBlock->cb_lock);
}
return AcceptTCB;
}
}
AcceptIrpCancelled:
//
// We couldn't get a needed resource or event handler
// did not take this. Free any that we
// did get, and fall through to the 'return NULL' code.
//
if (ConnReq != NULL)
FreeConnReq(ConnReq);
if (AcceptTCB != NULL)
FreeTCB(AcceptTCB);
DELAY_DEREF_AO(ListenAO);
} else {
//
// No event handler, or no resource.
// Free the locks, and return NULL.
//
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
}
return NULL;
}
//
// If we get here, the address object wasn't valid.
//
KeReleaseSpinLockFromDpcLevel(&ListenAO->ao_lock);
return NULL;
}
//* FindMSS - Find the MSS option in a segment.
//
// Called when a SYN is received to find the MSS option in a segment.
// If we don't find one, we assume the worst and return one based on
// the minimum MTU.
//
ushort // Returns: MSS to be used.
FindMSS(
TCPHeader UNALIGNED *TCP) // TCP header to be searched.
{
uint OptSize;
uchar *OptPtr;
OptSize = TCP_HDR_SIZE(TCP) - sizeof(TCPHeader);
OptPtr = (uchar *)(TCP + 1);
while (OptSize) {
if (*OptPtr == TCP_OPT_EOL)
break;
if (*OptPtr == TCP_OPT_NOP) {
OptPtr++;
OptSize--;
continue;
}
if (*OptPtr == TCP_OPT_MSS) {
if (OptPtr[1] == MSS_OPT_SIZE) {
ushort TempMss = *(ushort UNALIGNED *)(OptPtr + 2);
if (TempMss != 0)
return net_short(TempMss);
else
break; // MSS size of 0, use default.
} else
break; // Bad option size, use default.
} else {
//
// Unknown option. Skip over it.
//
if (OptPtr[1] == 0 || OptPtr[1] > OptSize)
break; // Bad option length, bail out.
OptSize -= OptPtr[1];
OptPtr += OptPtr[1];
}
}
return DEFAULT_MSS;
}
//* ACKAndDrop - Acknowledge a segment, and drop it.
//
// Called from within the receive code when we need to drop a segment that's
// outside the receive window.
//
void // Returns: Nothing.
ACKAndDrop(
TCPRcvInfo *RI, // Receive info for incoming segment.
TCB *RcvTCB) // TCB for incoming segment.
{
if (!(RI->tri_flags & TCP_FLAG_RST)) {
if (RcvTCB->tcb_state == TCB_TIME_WAIT) {
//
// In TIME_WAIT, we only ACK duplicates/retransmissions
// of our peer's FIN segment.
//
// REVIEW: We're currently fairly loose on the sequence
// number check here.
//
if ((RI->tri_flags & TCP_FLAG_FIN) &&
SEQ_LTE(RI->tri_seq, RcvTCB->tcb_rcvnext)) {
// Restart 2MSL timer and proceed with sending the ACK.
START_TCB_TIMER(RcvTCB->tcb_rexmittimer, MAX_REXMIT_TO);
} else {
// Drop this segment without an ACK.
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return;
}
}
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
SendACK(RcvTCB);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
}
//* ACKData - Acknowledge data.
//
// Called from the receive handler to acknowledge data. We're given the
// TCB and the new value of senduna. We walk down the send queue pulling
// off sends and putting them on the complete queue until we hit the end
// or we acknowledge the specified number of bytes of data.
//
// NOTE: We manipulate the send refcnt and acked flag without taking a lock.
// This is OK in the VxD version where locks don't mean anything anyway, but
// in the port to NT we'll need to add locking. The lock will have to be
// taken in the transmit complete routine. We can't use a lock in the TCB,
// since the TCB could go away before the transmit complete happens, and a
// lock in the TSR would be overkill, so it's probably best to use a global
// lock for this. If that causes too much contention, we could use a set of
// locks and pass a pointer to the appropriate lock back as part of the
// transmit confirm context. This lock pointer would also need to be stored
// in the TCB.
//
void // Returns: Nothing.
ACKData(
TCB *ACKTcb, // TCB from which to pull data.
SeqNum SendUNA) // New value of send una.
{
Queue *End, *Current; // End and current elements.
Queue *TempQ, *EndQ;
Queue *LastCmplt; // Last one we completed.
TCPSendReq *CurrentTSR; // Current send req we're looking at.
PNDIS_BUFFER CurrentBuffer; // Current NDIS_BUFFER.
uint Updated = FALSE;
uint BufLength;
int Amount, OrigAmount;
long Result;
KIRQL OldIrql;
uint Temp;
CHECK_STRUCT(ACKTcb, tcb);
CheckTCBSends(ACKTcb);
Amount = SendUNA - ACKTcb->tcb_senduna;
ASSERT(Amount > 0);
//
// Since this is an acknowledgement of receipt by our peer for previously
// unacknowledged data, it implies forward reachablility.
//
if (ACKTcb->tcb_rce != NULL)
ConfirmForwardReachability(ACKTcb->tcb_rce);
//
// Do a quick check to see if this acks everything that we have. If it
// does, handle it right away. We can only do this in the ESTABLISHED
// state, because we blindly update sendnext, and that can only work if we
// haven't sent a FIN.
//
if ((Amount == (int) ACKTcb->tcb_unacked) &&
ACKTcb->tcb_state == TCB_ESTAB) {
//
// Everything is acked.
//
ASSERT(!EMPTYQ(&ACKTcb->tcb_sendq));
TempQ = ACKTcb->tcb_sendq.q_next;
INITQ(&ACKTcb->tcb_sendq);
ACKTcb->tcb_sendnext = SendUNA;
ACKTcb->tcb_senduna = SendUNA;
ASSERT(ACKTcb->tcb_sendnext == ACKTcb->tcb_sendmax);
ACKTcb->tcb_cursend = NULL;
ACKTcb->tcb_sendbuf = NULL;
ACKTcb->tcb_sendofs = 0;
ACKTcb->tcb_sendsize = 0;
ACKTcb->tcb_unacked = 0;
//
// Now walk down the list of send requests. If the reference count
// has gone to 0, put it on the send complete queue.
//
KeAcquireSpinLock(&RequestCompleteLock, &OldIrql);
EndQ = &ACKTcb->tcb_sendq;
do {
CurrentTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, TempQ, tr_q),
TCPSendReq, tsr_req);
CHECK_STRUCT(CurrentTSR, tsr);
TempQ = CurrentTSR->tsr_req.tr_q.q_next;
CurrentTSR->tsr_req.tr_status = TDI_SUCCESS;
Result = InterlockedDecrement(&CurrentTSR->tsr_refcnt);
ASSERT(Result >= 0);
if (Result <= 0) {
// No more references are outstanding, the send can be
// completed.
// If we've sent directly from this send, NULL out the next
// pointer for the last buffer in the chain.
if (CurrentTSR->tsr_lastbuf != NULL) {
NDIS_BUFFER_LINKAGE(CurrentTSR->tsr_lastbuf) = NULL;
CurrentTSR->tsr_lastbuf = NULL;
}
ACKTcb->tcb_totaltime += (TCPTime - CurrentTSR->tsr_time);
Temp = ACKTcb->tcb_bcountlow;
ACKTcb->tcb_bcountlow += CurrentTSR->tsr_size;
ACKTcb->tcb_bcounthi += (Temp > ACKTcb->tcb_bcountlow ? 1 : 0);
ENQUEUE(&SendCompleteQ, &CurrentTSR->tsr_req.tr_q);
}
} while (TempQ != EndQ);
RequestCompleteFlags |= SEND_REQUEST_COMPLETE;
KeReleaseSpinLock(&RequestCompleteLock, OldIrql);
CheckTCBSends(ACKTcb);
return;
}
OrigAmount = Amount;
End = QEND(&ACKTcb->tcb_sendq);
Current = QHEAD(&ACKTcb->tcb_sendq);
LastCmplt = NULL;
while (Amount > 0 && Current != End) {
CurrentTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, Current, tr_q),
TCPSendReq, tsr_req);
CHECK_STRUCT(CurrentTSR, tsr);
if (Amount >= (int) CurrentTSR->tsr_unasize) {
// This is completely acked. Just advance to the next one.
Amount -= CurrentTSR->tsr_unasize;
LastCmplt = Current;
Current = QNEXT(Current);
continue;
}
//
// This one is only partially acked. Update his offset and NDIS buffer
// pointer, and break out. We know that Amount is < the unacked size
// in this buffer, we we can walk the NDIS buffer chain without fear
// of falling off the end.
//
CurrentBuffer = CurrentTSR->tsr_buffer;
ASSERT(CurrentBuffer != NULL);
ASSERT(Amount < (int) CurrentTSR->tsr_unasize);
CurrentTSR->tsr_unasize -= Amount;
BufLength = NdisBufferLength(CurrentBuffer) - CurrentTSR->tsr_offset;
if (Amount >= (int) BufLength) {
do {
Amount -= BufLength;
CurrentBuffer = NDIS_BUFFER_LINKAGE(CurrentBuffer);
ASSERT(CurrentBuffer != NULL);
BufLength = NdisBufferLength(CurrentBuffer);
} while (Amount >= (int) BufLength);
CurrentTSR->tsr_offset = Amount;
CurrentTSR->tsr_buffer = CurrentBuffer;
} else
CurrentTSR->tsr_offset += Amount;
Amount = 0;
break;
}
#if DBG
//
// We should always be able to remove at least Amount bytes, except in
// the case where a FIN has been sent. In that case we should be off
// by exactly one. In the debug builds we'll check this.
//
if (Amount != 0 && (!(ACKTcb->tcb_flags & FIN_SENT) || Amount != 1))
DbgBreakPoint();
#endif
if (SEQ_GT(SendUNA, ACKTcb->tcb_sendnext)) {
if (Current != End) {
//
// Need to reevaluate CurrentTSR, in case we bailed out of the
// above loop after updating Current but before updating
// CurrentTSR.
//
CurrentTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, Current, tr_q),
TCPSendReq, tsr_req);
CHECK_STRUCT(CurrentTSR, tsr);
ACKTcb->tcb_cursend = CurrentTSR;
ACKTcb->tcb_sendbuf = CurrentTSR->tsr_buffer;
ACKTcb->tcb_sendofs = CurrentTSR->tsr_offset;
ACKTcb->tcb_sendsize = CurrentTSR->tsr_unasize;
} else {
ACKTcb->tcb_cursend = NULL;
ACKTcb->tcb_sendbuf = NULL;
ACKTcb->tcb_sendofs = 0;
ACKTcb->tcb_sendsize = 0;
}
ACKTcb->tcb_sendnext = SendUNA;
}
//
// Now update tcb_unacked with the amount we tried to ack minus the
// amount we didn't ack (Amount should be 0 or 1 here).
//
ASSERT(Amount == 0 || Amount == 1);
ACKTcb->tcb_unacked -= OrigAmount - Amount;
ASSERT(*(int *)&ACKTcb->tcb_unacked >= 0);
ACKTcb->tcb_senduna = SendUNA;
//
// If we've acked any here, LastCmplt will be non-null, and Current will
// point to the send that should be at the start of the queue. Splice
// out the completed ones and put them on the end of the send completed
// queue, and update the TCB send queue.
//
if (LastCmplt != NULL) {
Queue *FirstCmplt;
TCPSendReq *FirstTSR, *EndTSR;
ASSERT(!EMPTYQ(&ACKTcb->tcb_sendq));
FirstCmplt = QHEAD(&ACKTcb->tcb_sendq);
//
// If we've acked everything, just reinit the queue.
//
if (Current == End) {
INITQ(&ACKTcb->tcb_sendq);
} else {
//
// There's still something on the queue. Just update it.
//
ACKTcb->tcb_sendq.q_next = Current;
Current->q_prev = &ACKTcb->tcb_sendq;
}
CheckTCBSends(ACKTcb);
//
// Now walk down the lists of things acked. If the refcnt on the send
// is 0, go ahead and put him on the send complete Q. Otherwise set
// the ACKed bit in the send, and he'll be completed when the count
// goes to 0 in the transmit confirm.
//
// Note that we haven't done any locking here. This will probably
// need to change in the port to NT.
//
// Set FirstTSR to the first TSR we'll complete, and EndTSR to be
// the first TSR that isn't completed.
//
FirstTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, FirstCmplt, tr_q),
TCPSendReq, tsr_req);
EndTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, Current, tr_q),
TCPSendReq, tsr_req);
CHECK_STRUCT(FirstTSR, tsr);
ASSERT(FirstTSR != EndTSR);
//
// Now walk the list of ACKed TSRs. If we can complete one, put him
// on the complete queue.
//
KeAcquireSpinLockAtDpcLevel(&RequestCompleteLock);
while (FirstTSR != EndTSR) {
TempQ = QNEXT(&FirstTSR->tsr_req.tr_q);
CHECK_STRUCT(FirstTSR, tsr);
FirstTSR->tsr_req.tr_status = TDI_SUCCESS;
//
// The tsr_lastbuf->Next field is zapped to 0 when the tsr_refcnt
// goes to 0, so we don't need to do it here.
//
// Decrement the reference put on the send buffer when it was
// initialized indicating the send has been acknowledged.
//
Result = InterlockedDecrement(&(FirstTSR->tsr_refcnt));
ASSERT(Result >= 0);
if (Result <= 0) {
//
// No more references are outstanding, the send can be
// completed.
//
// If we've sent directly from this send, NULL out the next
// pointer for the last buffer in the chain.
//
if (FirstTSR->tsr_lastbuf != NULL) {
NDIS_BUFFER_LINKAGE(FirstTSR->tsr_lastbuf) = NULL;
FirstTSR->tsr_lastbuf = NULL;
}
ACKTcb->tcb_totaltime += (TCPTime - CurrentTSR->tsr_time);
Temp = ACKTcb->tcb_bcountlow;
ACKTcb->tcb_bcountlow += CurrentTSR->tsr_size;
ACKTcb->tcb_bcounthi += (Temp > ACKTcb->tcb_bcountlow ? 1 : 0);
ENQUEUE(&SendCompleteQ, &FirstTSR->tsr_req.tr_q);
}
FirstTSR = CONTAINING_RECORD(QSTRUCT(TCPReq, TempQ, tr_q),
TCPSendReq, tsr_req);
}
RequestCompleteFlags |= SEND_REQUEST_COMPLETE;
KeReleaseSpinLockFromDpcLevel(&RequestCompleteLock);
}
}
//* TrimPacket - Trim the leading edge of a Packet.
//
// A utility routine to trim the front of a Packet. We take in an amount
// to trim off (which may be 0) and adjust the pointer in the first buffer
// in the chain forward by that much. If there isn't that much in the first
// buffer, we move onto the next one. If we run out of buffers we'll return
// a pointer to the last buffer in the chain, with a size of 0. It's the
// caller's responsibility to catch this.
// REVIEW - Move this to subr.c?
//
IPv6Packet * // Returns: A pointer to the new start, or NULL.
TrimPacket(
IPv6Packet *Packet, // Packet to be trimmed.
uint TrimAmount) // Amount to be trimmed.
{
uint TrimThisTime;
ASSERT(Packet != NULL);
while (TrimAmount) {
ASSERT(Packet != NULL);
TrimThisTime = MIN(TrimAmount, Packet->ContigSize);
TrimAmount -= TrimThisTime;
Packet->Position += TrimThisTime;
(uchar *)Packet->Data += TrimThisTime;
Packet->TotalSize -= TrimThisTime;
if ((Packet->ContigSize -= TrimThisTime) == 0) {
//
// Ran out of space in current buffer.
// Check for possibility of more data buffers in current packet.
//
if (Packet->TotalSize != 0) {
//
// Get more contiguous data.
//
PacketPullupSubr(Packet, 0, 1, 0);
continue;
}
//
// Couldn't do a pullup, so see if there's another packet
// hanging on this chain.
//
if (Packet->Next != NULL) {
IPv6Packet *Temp;
//
// There's another packet following. Toss this one.
//
Temp = Packet;
Packet = Packet->Next;
Temp->Next = NULL;
FreePacketChain(Temp);
} else {
//
// Ran out of Packets. Just return this one.
//
break;
}
}
}
return Packet;
}
//* FreePacketChain - Free a Packet chain.
//
// Called to free a chain of IPv6Packets. Only want to free that which
// we (the TCP/IPv6 stack) have allocated. Don't try to free anything
// passed up to us from lower layers.
//
void // Returns: Nothing.
FreePacketChain(
IPv6Packet *Packet) // First Packet in chain to be freed.
{
void *Aux;
while (Packet != NULL) {
PacketPullupCleanup(Packet);
if (Packet->Flags & PACKET_OURS) {
IPv6Packet *Temp;
Temp = Packet;
Packet = Packet->Next;
ExFreePool(Temp);
} else
Packet = Packet->Next;
}
}
IPv6Packet DummyPacket;
//* PullFromRAQ - Pull segments from the reassembly queue.
//
// Called when we've received frames out of order, and have some segments
// on the reassembly queue. We'll walk down the reassembly list, segments
// that are overlapped by the current receive next variable. When we get
// to one that doesn't completely overlap we'll trim it to fit the next
// receive sequence number, and pull it from the queue.
//
IPv6Packet *
PullFromRAQ(
TCB *RcvTCB, // TCB to pull from.
TCPRcvInfo *RcvInfo, // TCPRcvInfo structure for current segment.
uint *Size) // Where to update the size of the current segment.
{
TCPRAHdr *CurrentTRH; // Current TCP RA Header being examined.
TCPRAHdr *TempTRH; // Temporary variable.
SeqNum NextSeq; // Next sequence number we want.
IPv6Packet *NewPacket; // Packet after trimming.
SeqNum NextTRHSeq; // Sequence number immediately after current TRH.
int Overlap; // Overlap between current TRH and NextSeq.
CHECK_STRUCT(RcvTCB, tcb);
CurrentTRH = RcvTCB->tcb_raq;
NextSeq = RcvTCB->tcb_rcvnext;
while (CurrentTRH != NULL) {
CHECK_STRUCT(CurrentTRH, trh);
ASSERT(!(CurrentTRH->trh_flags & TCP_FLAG_SYN));
if (SEQ_LT(NextSeq, CurrentTRH->trh_start)) {
#if DBG
*Size = 0;
#endif
return NULL; // The next TRH starts too far down.
}
NextTRHSeq = CurrentTRH->trh_start + CurrentTRH->trh_size +
((CurrentTRH->trh_flags & TCP_FLAG_FIN) ? 1 : 0);
if (SEQ_GTE(NextSeq, NextTRHSeq)) {
//
// The current TRH is overlapped completely. Free it and continue.
//
FreePacketChain(CurrentTRH->trh_buffer);
TempTRH = CurrentTRH->trh_next;
ExFreePool(CurrentTRH);
CurrentTRH = TempTRH;
RcvTCB->tcb_raq = TempTRH;
if (TempTRH == NULL) {
//
// We've just cleaned off the RAQ. We can go back on the
// fast path now.
//
if (--(RcvTCB->tcb_slowcount) == 0) {
RcvTCB->tcb_fastchk &= ~TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
break;
}
} else {
Overlap = NextSeq - CurrentTRH->trh_start;
RcvInfo->tri_seq = NextSeq;
RcvInfo->tri_flags = CurrentTRH->trh_flags;
RcvInfo->tri_urgent = CurrentTRH->trh_urg;
if (Overlap != (int) CurrentTRH->trh_size) {
NewPacket = TrimPacket(CurrentTRH->trh_buffer, Overlap);
*Size = CurrentTRH->trh_size - Overlap;
} else {
//
// This completely overlaps the data in this segment, but the
// sequence number doesn't overlap completely. There must
// be a FIN in the TRH. We'll just return some bogus value
// that nobody will look at with a size of 0.
//
FreePacketChain(CurrentTRH->trh_buffer);
ASSERT(CurrentTRH->trh_flags & TCP_FLAG_FIN);
NewPacket =&DummyPacket;
*Size = 0;
}
RcvTCB->tcb_raq = CurrentTRH->trh_next;
if (RcvTCB->tcb_raq == NULL) {
//
// We've just cleaned off the RAQ. We can go back on the
// fast path now.
//
if (--(RcvTCB->tcb_slowcount) == 0) {
RcvTCB->tcb_fastchk &= ~TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
}
ExFreePool(CurrentTRH);
return NewPacket;
}
}
#if DBG
*Size = 0;
#endif
return NULL;
}
//* CreateTRH - Create a TCP reassembly header.
//
// This function tries to create a TCP reassembly header. We take as input
// a pointer to the previous TRH in the chain, the IPv6Packet to put on,
// etc. and try to create and link in a TRH. The caller must hold the lock
// on the TCB when this is called.
//
uint // Returns: TRUE if we created it, FALSE otherwise.
CreateTRH(
TCPRAHdr *PrevTRH, // TRH to insert after.
IPv6Packet *Packet, // IP Packet chain.
TCPRcvInfo *RcvInfo, // RcvInfo for this TRH.
int Size) // Size in bytes of data.
{
TCPRAHdr *NewTRH;
IPv6Packet *NewPacket;
ASSERT((Size > 0) || (RcvInfo->tri_flags & TCP_FLAG_FIN));
NewTRH = ExAllocatePoolWithTagPriority(NonPagedPool, sizeof(TCPRAHdr),
TCP6_TAG, LowPoolPriority);
if (NewTRH == NULL)
return FALSE;
NewPacket = ExAllocatePoolWithTagPriority(NonPagedPool,
sizeof(IPv6Packet) + Size,
TCP6_TAG, LowPoolPriority);
if (NewPacket == NULL) {
ExFreePool(NewTRH);
return FALSE;
}
#if DBG
NewTRH->trh_sig = trh_signature;
#endif
NewPacket->Next = NULL;
NewPacket->Position = 0;
NewPacket->FlatData = (uchar *)(NewPacket + 1);
NewPacket->Data = NewPacket->FlatData;
NewPacket->ContigSize = (uint)Size;
NewPacket->TotalSize = (uint)Size;
NewPacket->NdisPacket = NULL;
NewPacket->AuxList = NULL;
NewPacket->Flags = PACKET_OURS;
if (Size != 0)
CopyPacketToBuffer(NewPacket->Data, Packet, Size, Packet->Position);
NewTRH->trh_start = RcvInfo->tri_seq;
NewTRH->trh_flags = RcvInfo->tri_flags;
NewTRH->trh_size = Size;
NewTRH->trh_urg = RcvInfo->tri_urgent;
NewTRH->trh_buffer = NewPacket;
NewTRH->trh_end = NewPacket;
NewTRH->trh_next = PrevTRH->trh_next;
PrevTRH->trh_next = NewTRH;
return TRUE;
}
//* PutOnRAQ - Put a segment on the reassembly queue.
//
// Called during segment reception to put a segment on the reassembly
// queue. We try to use as few reassembly headers as possible, so if this
// segment has some overlap with an existing entry in the queue we'll just
// update the existing entry. If there is no overlap we'll create a new
// reassembly header. Combining URGENT data with non-URGENT data is tricky.
// If we get a segment that has urgent data that overlaps the front of a
// reassembly header we'll always mark the whole chunk as urgent - the value
// of the urgent pointer will mark the end of urgent data, so this is OK.
// If it only overlaps at the end, however, we won't combine, since we would
// have to mark previously non-urgent data as urgent. We'll trim the
// front of the incoming segment and create a new reassembly header. Also,
// if we have non-urgent data that overlaps at the front of a reassembly
// header containing urgent data we can't combine these two, since again we
// would mark non-urgent data as urgent.
// Our search will stop if we find an entry with a FIN.
// We assume that the TCB lock is held by the caller.
//
uint // Returns: TRUE if successful, FALSE otherwise.
PutOnRAQ(
TCB *RcvTCB, // TCB on which to reassemble.
TCPRcvInfo *RcvInfo, // RcvInfo for new segment.
IPv6Packet *Packet, // Packet chain for this segment.
uint Size) // Size in bytes of data in this segment.
{
TCPRAHdr *PrevTRH; // Previous reassembly header.
TCPRAHdr *CurrentTRH; // Current reassembly header.
SeqNum NextSeq; // Seq num of 1st byte after seg being reassembled.
SeqNum NextTRHSeq; // Sequence number of 1st byte after current TRH.
uint Created;
CHECK_STRUCT(RcvTCB, tcb);
ASSERT(RcvTCB->tcb_rcvnext != RcvInfo->tri_seq);
ASSERT(!(RcvInfo->tri_flags & TCP_FLAG_SYN));
NextSeq = RcvInfo->tri_seq + Size +
((RcvInfo->tri_flags & TCP_FLAG_FIN) ? 1 : 0);
PrevTRH = CONTAINING_RECORD(&RcvTCB->tcb_raq, TCPRAHdr, trh_next);
CurrentTRH = PrevTRH->trh_next;
//
// Walk down the reassembly queue, looking for the correct place to
// insert this, until we hit the end.
//
while (CurrentTRH != NULL) {
CHECK_STRUCT(CurrentTRH, trh);
ASSERT(!(CurrentTRH->trh_flags & TCP_FLAG_SYN));
NextTRHSeq = CurrentTRH->trh_start + CurrentTRH->trh_size +
((CurrentTRH->trh_flags & TCP_FLAG_FIN) ? 1 : 0);
//
// First, see if it starts beyond the end of the current TRH.
//
if (SEQ_LTE(RcvInfo->tri_seq, NextTRHSeq)) {
//
// We know the incoming segment doesn't start beyond the end
// of this TRH, so we'll either create a new TRH in front of
// this one or we'll merge the new segment onto this TRH.
// If the end of the current segment is in front of the start
// of the current TRH, we'll need to create a new TRH. Otherwise
// we'll merge these two.
//
if (SEQ_LT(NextSeq, CurrentTRH->trh_start))
break;
else {
//
// There's some overlap. If there's actually data in the
// incoming segment we'll merge it.
//
if (Size != 0) {
int FrontOverlap, BackOverlap;
IPv6Packet *NewPacket;
//
// We need to merge. If there's a FIN on the incoming
// segment that would fall inside this current TRH, we
// have a protocol violation from the remote peer. In
// this case just return, discarding the incoming segment.
//
if ((RcvInfo->tri_flags & TCP_FLAG_FIN) &&
SEQ_LTE(NextSeq, NextTRHSeq))
return TRUE;
//
// We have some overlap. Figure out how much.
//
FrontOverlap = CurrentTRH->trh_start - RcvInfo->tri_seq;
if (FrontOverlap > 0) {
//
// Have overlap in front. Allocate an IPv6Packet to
// to hold it, and copy it, unless we would have to
// combine non-urgent with urgent.
//
if (!(RcvInfo->tri_flags & TCP_FLAG_URG) &&
(CurrentTRH->trh_flags & TCP_FLAG_URG)) {
if (CreateTRH(PrevTRH, Packet, RcvInfo,
CurrentTRH->trh_start - RcvInfo->tri_seq)) {
PrevTRH = PrevTRH->trh_next;
CurrentTRH = PrevTRH->trh_next;
}
FrontOverlap = 0;
} else {
NewPacket = ExAllocatePoolWithTagPriority(
NonPagedPool,
sizeof(IPv6Packet) + FrontOverlap,
TCP6_TAG, LowPoolPriority);
if (NewPacket == NULL) {
// Couldn't allocate memory.
return TRUE;
}
NewPacket->Position = 0;
NewPacket->FlatData = (uchar *)(NewPacket + 1);
NewPacket->Data = NewPacket->FlatData;
NewPacket->ContigSize = FrontOverlap;
NewPacket->TotalSize = FrontOverlap;
NewPacket->NdisPacket = NULL;
NewPacket->AuxList = NULL;
NewPacket->Flags = PACKET_OURS;
CopyPacketToBuffer(NewPacket->Data, Packet,
FrontOverlap, Packet->Position);
CurrentTRH->trh_size += FrontOverlap;
//
// Put our new packet on the front of this
// reassembly header's packet list.
//
NewPacket->Next = CurrentTRH->trh_buffer;
CurrentTRH->trh_buffer = NewPacket;
CurrentTRH->trh_start = RcvInfo->tri_seq;
}
}
//
// We've updated the starting sequence number of this TRH
// if we needed to. Now look for back overlap. There
// can't be any back overlap if the current TRH has a FIN.
// Also we'll need to check for urgent data if there is
// back overlap.
//
if (!(CurrentTRH->trh_flags & TCP_FLAG_FIN)) {
BackOverlap = RcvInfo->tri_seq + Size - NextTRHSeq;
if ((BackOverlap > 0) &&
(RcvInfo->tri_flags & TCP_FLAG_URG) &&
!(CurrentTRH->trh_flags & TCP_FLAG_URG) &&
(FrontOverlap <= 0)) {
int AmountToTrim;
//
// The incoming segment has urgent data and
// overlaps on the back but not the front, and the
// current TRH has no urgent data. We can't
// combine into this TRH, so trim the front of the
// incoming segment to NextTRHSeq and move to the
// next TRH.
AmountToTrim = NextTRHSeq - RcvInfo->tri_seq;
ASSERT(AmountToTrim >= 0);
ASSERT(AmountToTrim < (int) Size);
Packet = TrimPacket(Packet, (uint)AmountToTrim);
RcvInfo->tri_seq += AmountToTrim;
RcvInfo->tri_urgent -= AmountToTrim;
PrevTRH = CurrentTRH;
CurrentTRH = PrevTRH->trh_next;
Size -= AmountToTrim;
continue;
}
} else
BackOverlap = 0;
//
// Now if we have back overlap, copy it.
//
if (BackOverlap > 0) {
//
// We have back overlap. Get a buffer to copy it into.
// If we can't get one, we won't just return, because
// we may have updated the front and may need to
// update the urgent info.
//
NewPacket = ExAllocatePoolWithTagPriority(
NonPagedPool,
sizeof(IPv6Packet) + BackOverlap,
TCP6_TAG, LowPoolPriority);
if (NewPacket != NULL) {
// Allocation succeeded.
NewPacket->Position = 0;
NewPacket->FlatData = (uchar *)(NewPacket + 1);
NewPacket->Data = NewPacket->FlatData;
NewPacket->ContigSize = BackOverlap;
NewPacket->TotalSize = BackOverlap;
NewPacket->NdisPacket = NULL;
NewPacket->AuxList = NULL;
NewPacket->Flags = PACKET_OURS;
CopyPacketToBuffer(NewPacket->Data, Packet,
BackOverlap, Packet->Position +
NextTRHSeq - RcvInfo->tri_seq);
CurrentTRH->trh_size += BackOverlap;
NewPacket->Next = CurrentTRH->trh_end->Next;
CurrentTRH->trh_end->Next = NewPacket;
CurrentTRH->trh_end = NewPacket;
//
// This segment could also have FIN set.
// If it does, set the TRH flag.
//
// N.B. If there's another reassembly header after
// the current one, the data that we're about to
// put on the current header might already be
// on that subsequent header which, in that event,
// will already have the FIN flag set.
// Check for that case before recording the FIN.
//
if ((RcvInfo->tri_flags & TCP_FLAG_FIN) &&
!CurrentTRH->trh_next) {
CurrentTRH->trh_flags |= TCP_FLAG_FIN;
}
}
}
//
// Everything should be consistent now. If there's an
// urgent data pointer in the incoming segment, update the
// one in the TRH now.
//
if (RcvInfo->tri_flags & TCP_FLAG_URG) {
SeqNum UrgSeq;
//
// Have an urgent pointer. If the current TRH already
// has an urgent pointer, see which is bigger.
// Otherwise just use this one.
//
UrgSeq = RcvInfo->tri_seq + RcvInfo->tri_urgent;
if (CurrentTRH->trh_flags & TCP_FLAG_URG) {
SeqNum TRHUrgSeq;
TRHUrgSeq = CurrentTRH->trh_start +
CurrentTRH->trh_urg;
if (SEQ_LT(UrgSeq, TRHUrgSeq))
UrgSeq = TRHUrgSeq;
} else
CurrentTRH->trh_flags |= TCP_FLAG_URG;
CurrentTRH->trh_urg = UrgSeq - CurrentTRH->trh_start;
}
} else {
//
// We have a 0 length segment. The only interesting thing
// here is if there's a FIN on the segment. If there is,
// and the seq. # of the incoming segment is exactly after
// the current TRH, OR matches the FIN in the current TRH,
// we note it.
if (RcvInfo->tri_flags & TCP_FLAG_FIN) {
if (!(CurrentTRH->trh_flags & TCP_FLAG_FIN)) {
if (SEQ_EQ(NextTRHSeq, RcvInfo->tri_seq))
CurrentTRH->trh_flags |= TCP_FLAG_FIN;
else
KdBreakPoint();
}
else {
if (!(SEQ_EQ((NextTRHSeq-1), RcvInfo->tri_seq))) {
KdBreakPoint();
}
}
}
}
return TRUE;
}
} else {
//
// Look at the next TRH, unless the current TRH has a FIN. If he
// has a FIN, we won't save any data beyond that anyway.
//
if (CurrentTRH->trh_flags & TCP_FLAG_FIN)
return TRUE;
PrevTRH = CurrentTRH;
CurrentTRH = PrevTRH->trh_next;
}
}
//
// When we get here, we need to create a new TRH. If we create one and
// there was previously nothing on the reassembly queue, we'll have to
// move off the fast receive path.
//
CurrentTRH = RcvTCB->tcb_raq;
Created = CreateTRH(PrevTRH, Packet, RcvInfo, (int)Size);
if (Created && CurrentTRH == NULL) {
RcvTCB->tcb_slowcount++;
RcvTCB->tcb_fastchk |= TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
} else if (!Created) {
return FALSE;
}
return TRUE;
}
//* HandleFastXmit - Handles fast retransmit algorithm. See RFC 2581.
//
// Called by TCPReceive to determine if we should retransmit a segment
// without waiting for retransmit timeout to fire.
//
BOOLEAN // Returns: TRUE if the segment got retransmitted, FALSE otherwise.
HandleFastXmit(
TCB *RcvTCB, // Connection context for this receive.
TCPRcvInfo *RcvInfo) // Pointer to rcvd TCP Header information.
{
uint CWin;
RcvTCB->tcb_dupacks++;
if (RcvTCB->tcb_dupacks == MaxDupAcks) {
//
// We're going to do a fast retransmit.
// Stop the retransmit timer and any round-trip time
// calculations we might have been running.
//
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
RcvTCB->tcb_rtt = 0;
if (!(RcvTCB->tcb_flags & FLOW_CNTLD)) {
//
// Don't let the slow start threshold go
// below 2 segments.
//
RcvTCB->tcb_ssthresh =
MAX(MIN(RcvTCB->tcb_cwin, RcvTCB->tcb_sendwin) / 2,
(uint) RcvTCB->tcb_mss * 2);
}
//
// Inflate the congestion window by the number of segments
// which have presumably left the network.
//
CWin = RcvTCB->tcb_ssthresh + (MaxDupAcks * RcvTCB->tcb_mss);
//
// Recall the segment in question and send it out.
// Note that tcb_lock will be dereferenced by the caller.
//
ResetAndFastSend(RcvTCB, RcvTCB->tcb_senduna, CWin);
return TRUE;
} else {
int SendWin;
uint AmtOutstanding;
//
// REVIEW: At least the first part of this check is redundant.
//
if (SEQ_EQ(RcvTCB->tcb_senduna, RcvInfo->tri_ack) &&
(SEQ_LT(RcvTCB->tcb_sendwl1, RcvInfo->tri_seq) ||
(SEQ_EQ(RcvTCB->tcb_sendwl1, RcvInfo->tri_seq) &&
SEQ_LTE(RcvTCB->tcb_sendwl2, RcvInfo->tri_ack)))) {
RcvTCB->tcb_sendwin = RcvInfo->tri_window;
RcvTCB->tcb_maxwin = MAX(RcvTCB->tcb_maxwin, RcvInfo->tri_window);
RcvTCB->tcb_sendwl1 = RcvInfo->tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo->tri_ack;
}
if (RcvTCB->tcb_dupacks > MaxDupAcks) {
//
// Update the congestion window to reflect the fact that the
// duplicate ack presumably indicates that the previous frame
// was received by our peer and has thus left the network.
//
RcvTCB->tcb_cwin += RcvTCB->tcb_mss;
}
//
// Check if we need to set tcb_force.
//
if ((RcvTCB->tcb_cwin + RcvTCB->tcb_mss) < RcvTCB->tcb_sendwin) {
AmtOutstanding = (uint)(RcvTCB->tcb_sendnext -
RcvTCB->tcb_senduna);
SendWin = (int)(MIN(RcvTCB->tcb_sendwin, RcvTCB->tcb_cwin) -
AmtOutstanding);
if (SendWin < RcvTCB->tcb_mss) {
RcvTCB->tcb_force = 1;
}
}
}
return FALSE;
}
//* TCPReceive - Receive an incoming TCP segment.
//
// This is the routine called by IPv6 when we need to receive a TCP segment.
// In general, we follow the RFC 793 event processing section pretty closely,
// but there is a 'fast path' where we make some quick checks on the incoming
// segment, and if it matches we deliver it immediately.
//
uchar // Returns: next header value (always IP_PROTOCOL_NONE for TCP).
TCPReceive(
IPv6Packet *Packet) // Packet IP handed up to us.
{
NetTableEntry *NTE;
TCPHeader UNALIGNED *TCP; // The TCP header.
uint DataOffset; // Offset from start of TCP header to data.
ushort Checksum;
TCPRcvInfo RcvInfo; // Local swapped copy of receive info.
uint SrcScopeId; // Scope id of remote address, if applicable.
uint DestScopeId; // Scope id of local address, if applicable.
TCB *RcvTCB; // TCB on which to receive the packet.
uint Inserted;
uint Actions; // Flags for future actions to be performed.
uint BytesTaken;
uint NewSize;
BOOLEAN UseIsn = FALSE;
SeqNum Isn = 0;
//
// REVIEW: Expediency hacks to get something working.
//
uint Size; // Probably safe to just change name to PayloadLength below.
//
// TCP only works with unicast addresses. If this packet was
// received on a unicast address, then Packet->NTEorIF will be an
// NTE. So drop packets if we don't have an NTE.
// (IPv6HeaderReceive checks validity.) But the converse isn't
// true, we could have an NTE here that is associated with the
// anycast/multicast address we received the packet on. So to
// guard against that, we verify that our NTE's address is the
// destination given in the packet.
//
if (!IsNTE(Packet->NTEorIF) ||
!IP6_ADDR_EQUAL(AlignAddr(&Packet->IP->Dest),
&(NTE = CastToNTE(Packet->NTEorIF))->Address)) {
// Packet's destination was not a valid unicast address of ours.
return IP_PROTOCOL_NONE; // Drop packet.
}
TStats.ts_insegs++;
//
// Verify that we have enough contiguous data to overlay a TCPHeader
// structure on the incoming packet. Then do so.
//
if (! PacketPullup(Packet, sizeof(TCPHeader), 1, 0)) {
// Pullup failed.
TStats.ts_inerrs++;
if (Packet->TotalSize < sizeof(TCPHeader)) {
BadPayloadLength:
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_BAD_PACKET,
"TCPv6: data buffer too small to contain TCP header\n"));
ICMPv6SendError(Packet,
ICMPv6_PARAMETER_PROBLEM,
ICMPv6_ERRONEOUS_HEADER_FIELD,
FIELD_OFFSET(IPv6Header, PayloadLength),
IP_PROTOCOL_NONE, FALSE);
}
return IP_PROTOCOL_NONE; // Drop packet.
}
TCP = (TCPHeader UNALIGNED *)Packet->Data;
//
// Verify checksum.
//
Checksum = ChecksumPacket(Packet->NdisPacket, Packet->Position,
Packet->FlatData, Packet->TotalSize,
Packet->SrcAddr, AlignAddr(&Packet->IP->Dest),
IP_PROTOCOL_TCP);
if (Checksum != 0xffff) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_NET_ERROR,
"TCPv6: Checksum failed %0x\n", Checksum));
TStats.ts_inerrs++;
return IP_PROTOCOL_NONE; // Drop packet.
}
//
// Now that we can read the header, pull out the header length field.
// Verify that we have enough contiguous data to hold any TCP options
// that may be present in the header, and skip over the entire header.
//
DataOffset = TCP_HDR_SIZE(TCP);
if (! PacketPullup(Packet, DataOffset, 1, 0)) {
TStats.ts_inerrs++;
if (Packet->TotalSize < DataOffset)
goto BadPayloadLength;
return IP_PROTOCOL_NONE; // Drop packet.
}
TCP = (TCPHeader UNALIGNED *)Packet->Data;
AdjustPacketParams(Packet, DataOffset);
Size = Packet->TotalSize;
//
// Verify IPSec was performed.
//
if (InboundSecurityCheck(Packet, IP_PROTOCOL_TCP, net_short(TCP->tcp_src),
net_short(TCP->tcp_dest), NTE->IF) != TRUE) {
//
// No policy was found or the policy indicated to drop the packet.
//
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_NET_ERROR,
"TCPReceive: IPSec Policy caused packet to be dropped\n"));
return IP_PROTOCOL_NONE; // Drop packet.
}
//
// The packet is valid.
// Get the info we need and byte swap it.
//
RcvInfo.tri_seq = net_long(TCP->tcp_seq);
RcvInfo.tri_ack = net_long(TCP->tcp_ack);
RcvInfo.tri_window = (uint)net_short(TCP->tcp_window);
RcvInfo.tri_urgent = (uint)net_short(TCP->tcp_urgent);
RcvInfo.tri_flags = (uint)TCP->tcp_flags;
//
// Determine the appropriate scope id for our packet's addresses.
// Note that multicast addresses were forbidden above.
// We use DetermineScopeId instead of just indexing into ZoneIndices
// because we need the "user-level" scope id here.
//
SrcScopeId = DetermineScopeId(Packet->SrcAddr, NTE->IF);
DestScopeId = DetermineScopeId(&NTE->Address, NTE->IF);
//
// See if we have a TCP Control Block for this connection.
//
KeAcquireSpinLockAtDpcLevel(&TCBTableLock);
RcvTCB = FindTCB(AlignAddr(&Packet->IP->Dest), Packet->SrcAddr,
DestScopeId, SrcScopeId, TCP->tcp_dest, TCP->tcp_src);
if (RcvTCB == NULL) {
uchar DType;
//
// Didn't find a matching TCB, which means incoming segment doesn't
// belong to an existing connection.
//
KeReleaseSpinLockFromDpcLevel(&TCBTableLock);
//
// Make sure that the source address is reasonable
// before proceeding.
//
ASSERT(!IsInvalidSourceAddress(Packet->SrcAddr));
if (IsUnspecified(Packet->SrcAddr)) {
return IP_PROTOCOL_NONE;
}
//
// If this segment carries a SYN (and only a SYN), it's a
// connection initiation request.
//
if ((RcvInfo.tri_flags & (TCP_FLAG_SYN | TCP_FLAG_ACK |
TCP_FLAG_RST)) == TCP_FLAG_SYN) {
AddrObj *AO;
ValidNewConnectionRequest:
//
// We need to look for a matching address object.
// Want match for local address (+ scope id for scoped addresses),
// port and protocol.
//
KeAcquireSpinLockAtDpcLevel(&AddrObjTableLock);
AO = GetBestAddrObj(AlignAddr(&Packet->IP->Dest),
DestScopeId, TCP->tcp_dest,
IP_PROTOCOL_TCP, NTE->IF);
if (AO == NULL) {
//
// No address object. Free the lock, and send a RST.
//
KeReleaseSpinLockFromDpcLevel(&AddrObjTableLock);
goto SendReset;
}
//
// Found an AO. See if it has a listen indication.
// FindListenConn will free the lock on the AddrObjTable.
//
RcvTCB = FindListenConn(AO, Packet->SrcAddr, SrcScopeId,
TCP->tcp_src);
if (RcvTCB == NULL) {
//
// No listening connection. AddrObjTableLock was
// released by FindListenConn. Just send a RST.
//
goto SendReset;
}
CHECK_STRUCT(RcvTCB, tcb);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
//
// We found a listening connection. Initialize
// it now, and if it is actually to be accepted
// we'll send a SYN-ACK also.
//
ASSERT(RcvTCB->tcb_state == TCB_SYN_RCVD);
RcvTCB->tcb_daddr = *Packet->SrcAddr;
RcvTCB->tcb_saddr = Packet->IP->Dest;
RcvTCB->tcb_dscope_id = SrcScopeId;
RcvTCB->tcb_sscope_id = DestScopeId;
RcvTCB->tcb_dport = TCP->tcp_src;
RcvTCB->tcb_sport = TCP->tcp_dest;
RcvTCB->tcb_rcvnext = ++RcvInfo.tri_seq;
RcvTCB->tcb_rcvwinwatch = RcvTCB->tcb_rcvnext;
if (UseIsn) {
RcvTCB->tcb_sendnext = Isn;
} else {
GetRandomISN(&RcvTCB->tcb_sendnext, (uchar*)&RcvTCB->tcb_md5data);
}
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_remmss = FindMSS(TCP);
TStats.ts_passiveopens++;
RcvTCB->tcb_fastchk |= TCP_FLAG_IN_RCV;
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
Inserted = InsertTCB(RcvTCB);
//
// Get the lock on it, and see if it's been accepted.
//
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
if (!Inserted) {
// Couldn't insert it!.
CompleteConnReq(RcvTCB, TDI_CONNECTION_ABORTED);
RcvTCB->tcb_refcnt--;
TryToCloseTCB(RcvTCB, TCB_CLOSE_ABORTED, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
RcvTCB->tcb_fastchk &= ~TCP_FLAG_IN_RCV;
if (RcvTCB->tcb_flags & SEND_AFTER_RCV) {
RcvTCB->tcb_flags &= ~SEND_AFTER_RCV;
DelayAction(RcvTCB, NEED_OUTPUT);
}
if (RcvTCB->tcb_flags & CONN_ACCEPTED) {
//
// The connection was accepted. Finish the
// initialization, and send the SYN ack.
//
AcceptConn(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
} else {
//
// We don't know what to do about the
// connection yet. Return the pending listen,
// dereference the connection, and return.
//
CompleteConnReq(RcvTCB, TDI_SUCCESS);
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
}
SendReset:
//
// Not a SYN, no AddrObj available, or port filtered.
// Send a RST back to the sender.
//
SendRSTFromHeader(TCP, Packet->TotalSize, Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
return IP_PROTOCOL_NONE;
}
//
// We found a matching TCB. Get the lock on it, and continue.
//
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
KeReleaseSpinLockFromDpcLevel(&TCBTableLock);
//
// Do the fast path check. We can hit the fast path if the incoming
// sequence number matches our receive next and the masked flags
// match our 'predicted' flags.
//
CheckTCBRcv(RcvTCB);
RcvTCB->tcb_alive = TCPTime;
if (RcvTCB->tcb_rcvnext == RcvInfo.tri_seq &&
(RcvInfo.tri_flags & TCP_FLAGS_ALL) == RcvTCB->tcb_fastchk) {
Actions = 0;
RcvTCB->tcb_refcnt++;
//
// The fast path. We know all we have to do here is ack sends and
// deliver data. First try and ack data.
//
if (SEQ_LT(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LTE(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
uint CWin;
uint MSS;
//
// The ack acknowledges something. Pull the
// appropriate amount off the send q.
//
ACKData(RcvTCB, RcvInfo.tri_ack);
//
// If this acknowledges something we were running a RTT on,
// update that stuff now.
//
if (RcvTCB->tcb_rtt != 0 && SEQ_GT(RcvInfo.tri_ack,
RcvTCB->tcb_rttseq)) {
short RTT;
RTT = (short)(TCPTime - RcvTCB->tcb_rtt);
RcvTCB->tcb_rtt = 0;
RTT -= (RcvTCB->tcb_smrtt >> 3);
RcvTCB->tcb_smrtt += RTT;
RTT = (RTT >= 0 ? RTT : -RTT);
RTT -= (RcvTCB->tcb_delta >> 3);
RcvTCB->tcb_delta += RTT + RTT;
RcvTCB->tcb_rexmit = MIN(MAX(REXMIT_TO(RcvTCB),
MIN_RETRAN_TICKS),
MAX_REXMIT_TO);
}
if ((RcvTCB->tcb_dupacks >= MaxDupAcks) &&
((int)RcvTCB->tcb_ssthresh > 0)) {
//
// We were in fast retransmit mode, so this ACK is for
// our fast retransmitted frame. Set cwin to ssthresh
// so that cwin grows linearly from here.
//
RcvTCB->tcb_cwin = RcvTCB->tcb_ssthresh;
} else {
//
// Update the congestion window now.
//
CWin = RcvTCB->tcb_cwin;
MSS = RcvTCB->tcb_mss;
if (CWin < RcvTCB->tcb_maxwin) {
if (CWin < RcvTCB->tcb_ssthresh)
CWin += MSS;
else
CWin += (MSS * MSS)/CWin;
RcvTCB->tcb_cwin = CWin;
}
}
ASSERT(*(int *)&RcvTCB->tcb_cwin > 0);
//
// Since this isn't a duplicate ACK, reset the counter.
//
RcvTCB->tcb_dupacks = 0;
//
// We've acknowledged something, so reset the rexmit count.
// If there's still stuff outstanding, restart the rexmit
// timer.
//
RcvTCB->tcb_rexmitcnt = 0;
if (SEQ_EQ(RcvInfo.tri_ack, RcvTCB->tcb_sendmax))
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
else
START_TCB_TIMER(RcvTCB->tcb_rexmittimer, RcvTCB->tcb_rexmit);
//
// Since we've acknowledged data, we need to update the window.
//
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_maxwin = MAX(RcvTCB->tcb_maxwin, RcvInfo.tri_window);
RcvTCB->tcb_sendwl1 = RcvInfo.tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo.tri_ack;
//
// We've updated the window, remember to send some more.
//
Actions = (RcvTCB->tcb_unacked ? NEED_OUTPUT : 0);
} else {
//
// It doesn't ack anything. If it's an ack for something
// larger than we've sent then ACKAndDrop it.
//
if (SEQ_GT(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
//
// If it is a pure duplicate ack, check if we should
// do a fast retransmit.
//
if ((Size == 0) && SEQ_EQ(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LT(RcvTCB->tcb_senduna, RcvTCB->tcb_sendmax) &&
(RcvTCB->tcb_sendwin == RcvInfo.tri_window) &&
RcvInfo.tri_window) {
//
// See if fast rexmit can be done.
//
if (HandleFastXmit(RcvTCB, &RcvInfo)) {
return IP_PROTOCOL_NONE;
}
Actions = (RcvTCB->tcb_unacked ? NEED_OUTPUT : 0);
} else {
//
// Not a pure duplicate ack (Size != 0 or peer is
// advertising a new windows). Reset counter.
//
RcvTCB->tcb_dupacks = 0;
//
// If the ack matches our existing UNA, we need to see if
// we can update the window.
//
if (SEQ_EQ(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
(SEQ_LT(RcvTCB->tcb_sendwl1, RcvInfo.tri_seq) ||
(SEQ_EQ(RcvTCB->tcb_sendwl1, RcvInfo.tri_seq) &&
SEQ_LTE(RcvTCB->tcb_sendwl2, RcvInfo.tri_ack)))) {
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_maxwin = MAX(RcvTCB->tcb_maxwin,
RcvInfo.tri_window);
RcvTCB->tcb_sendwl1 = RcvInfo.tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo.tri_ack;
//
// Since we've updated the window, remember to send
// some more.
//
Actions = (RcvTCB->tcb_unacked ? NEED_OUTPUT : 0);
}
}
}
//
// Check to see if this packet contains any useable data.
//
NewSize = MIN((int) Size, RcvTCB->tcb_rcvwin);
if (NewSize != 0) {
RcvTCB->tcb_fastchk |= TCP_FLAG_IN_RCV;
BytesTaken = (*RcvTCB->tcb_rcvhndlr)(RcvTCB, RcvInfo.tri_flags,
Packet, NewSize);
RcvTCB->tcb_rcvnext += BytesTaken;
RcvTCB->tcb_rcvwin -= BytesTaken;
CheckTCBRcv(RcvTCB);
RcvTCB->tcb_fastchk &= ~TCP_FLAG_IN_RCV;
//
// If our peer is sending into an expanded window, then our
// peer must have received our ACK advertising said window.
// Take this as proof of forward reachability.
//
if (SEQ_GTE(RcvInfo.tri_seq + (int)NewSize,
RcvTCB->tcb_rcvwinwatch)) {
RcvTCB->tcb_rcvwinwatch = RcvTCB->tcb_rcvnext +
RcvTCB->tcb_rcvwin;
if (RcvTCB->tcb_rce != NULL)
ConfirmForwardReachability(RcvTCB->tcb_rce);
}
Actions |= (RcvTCB->tcb_flags & SEND_AFTER_RCV ? NEED_OUTPUT : 0);
RcvTCB->tcb_flags &= ~SEND_AFTER_RCV;
if ((RcvTCB->tcb_flags & ACK_DELAYED) ||
(BytesTaken != NewSize)) {
Actions |= NEED_ACK;
} else {
RcvTCB->tcb_flags |= ACK_DELAYED;
START_TCB_TIMER(RcvTCB->tcb_delacktimer, DEL_ACK_TICKS);
}
} else {
//
// The new size is 0. If the original size was not 0, we must
// have a 0 receive win and hence need to send an ACK to this
// probe.
//
Actions |= (Size ? NEED_ACK : 0);
}
if (Actions)
DelayAction(RcvTCB, Actions);
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
//
// This is the non-fast path.
//
//
// If we found a matching TCB in TIME_WAIT, and the received segment
// carries a SYN (and only a SYN), and the received segment has a sequence
// greater than the last received, kill the TIME_WAIT TCB and use its
// next sequence number to generate the initial sequence number of a
// new incarnation.
//
if ((RcvTCB->tcb_state == TCB_TIME_WAIT) &&
((RcvInfo.tri_flags & (TCP_FLAG_SYN | TCP_FLAG_ACK | TCP_FLAG_RST))
== TCP_FLAG_SYN) &&
SEQ_GT(RcvInfo.tri_seq, RcvTCB->tcb_rcvnext)) {
Isn = RcvTCB->tcb_sendnext + 128000;
UseIsn = TRUE;
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
TryToCloseTCB(RcvTCB, TCB_CLOSE_SUCCESS, DISPATCH_LEVEL);
RcvTCB = NULL;
goto ValidNewConnectionRequest;
}
//
// Make sure we can handle this frame. We can't handle it if we're
// in SYN_RCVD and the accept is still pending, or we're in a
// non-established state and already in the receive handler.
//
if ((RcvTCB->tcb_state == TCB_SYN_RCVD &&
!(RcvTCB->tcb_flags & CONN_ACCEPTED)) ||
(RcvTCB->tcb_state != TCB_ESTAB && (RcvTCB->tcb_fastchk &
TCP_FLAG_IN_RCV))) {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
return IP_PROTOCOL_NONE;
}
//
// If it's closed, it's a temporary zombie TCB. Reset the sender.
//
if (RcvTCB->tcb_state == TCB_CLOSED || CLOSING(RcvTCB) ||
((RcvTCB->tcb_flags & (GC_PENDING | TW_PENDING)) == GC_PENDING)) {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
SendRSTFromHeader(TCP, Packet->TotalSize, Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
return IP_PROTOCOL_NONE;
}
//
// At this point, we have a connection, and it's locked. Following
// the 'Segment Arrives' section of 793, the next thing to check is
// if this connection is in SynSent state.
//
if (RcvTCB->tcb_state == TCB_SYN_SENT) {
ASSERT(RcvTCB->tcb_flags & ACTIVE_OPEN);
//
// Check the ACK bit. Since we don't send data with our SYNs, the
// check we make is for the ack to exactly match our SND.NXT.
//
if (RcvInfo.tri_flags & TCP_FLAG_ACK) {
// ACK is set.
if (!SEQ_EQ(RcvInfo.tri_ack, RcvTCB->tcb_sendnext)) {
// Bad ACK value.
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
// Send a RST back at him.
SendRSTFromHeader(TCP, Packet->TotalSize,
Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
return IP_PROTOCOL_NONE;
}
}
if (RcvInfo.tri_flags & TCP_FLAG_RST) {
//
// There's an acceptable RST. We'll persist here, sending
// another SYN in PERSIST_TIMEOUT ms, until we fail from too
// many retries.
//
if (RcvTCB->tcb_rexmitcnt == MaxConnectRexmitCount) {
//
// We've had a positive refusal, and one more rexmit
// would time us out, so close the connection now.
//
CompleteConnReq(RcvTCB, TDI_CONN_REFUSED);
TryToCloseTCB(RcvTCB, TCB_CLOSE_REFUSED, DISPATCH_LEVEL);
} else {
START_TCB_TIMER(RcvTCB->tcb_rexmittimer, PERSIST_TIMEOUT);
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
}
return IP_PROTOCOL_NONE;
}
//
// See if we have a SYN. If we do, we're going to change state
// somehow (either to ESTABLISHED or SYN_RCVD).
//
if (RcvInfo.tri_flags & TCP_FLAG_SYN) {
RcvTCB->tcb_refcnt++;
//
// We have a SYN. Go ahead and record the sequence number and
// window info.
//
RcvTCB->tcb_rcvnext = ++RcvInfo.tri_seq;
RcvTCB->tcb_rcvwinwatch = RcvTCB->tcb_rcvnext;
if (RcvInfo.tri_flags & TCP_FLAG_URG) {
// Urgent data. Update the pointer.
if (RcvInfo.tri_urgent != 0)
RcvInfo.tri_urgent--;
else
RcvInfo.tri_flags &= ~TCP_FLAG_URG;
}
RcvTCB->tcb_remmss = FindMSS(TCP);
RcvTCB->tcb_mss = MIN(RcvTCB->tcb_mss, RcvTCB->tcb_remmss);
ASSERT(RcvTCB->tcb_mss > 0);
RcvTCB->tcb_rexmitcnt = 0;
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
AdjustRcvWin(RcvTCB);
if (RcvInfo.tri_flags & TCP_FLAG_ACK) {
//
// Our SYN has been acked. Update SND.UNA and stop the
// retrans timer.
//
RcvTCB->tcb_senduna = RcvInfo.tri_ack;
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_maxwin = RcvInfo.tri_window;
RcvTCB->tcb_sendwl1 = RcvInfo.tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo.tri_ack;
GoToEstab(RcvTCB);
//
// We know our peer received our SYN.
//
if (RcvTCB->tcb_rce != NULL)
ConfirmForwardReachability(RcvTCB->tcb_rce);
//
// Remove whatever command exists on this connection.
//
CompleteConnReq(RcvTCB, TDI_SUCCESS);
//
// If data has been queued already, send the first data segment
// with the ACK. Otherwise, send a pure ACK.
//
if (RcvTCB->tcb_unacked) {
RcvTCB->tcb_refcnt++;
TCPSend(RcvTCB, DISPATCH_LEVEL);
} else {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
SendACK(RcvTCB);
}
//
// Now handle other data and controls. To do this we need
// to reaquire the lock, and make sure we haven't started
// closing it.
//
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
if (!CLOSING(RcvTCB)) {
//
// We haven't started closing it. Turn off the
// SYN flag and continue processing.
//
RcvInfo.tri_flags &= ~TCP_FLAG_SYN;
if ((RcvInfo.tri_flags & TCP_FLAGS_ALL) !=
TCP_FLAG_ACK || Size != 0)
goto NotSYNSent;
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
} else {
//
// A SYN, but not an ACK. Go to SYN_RCVD.
//
RcvTCB->tcb_state = TCB_SYN_RCVD;
RcvTCB->tcb_sendnext = RcvTCB->tcb_senduna;
SendSYN(RcvTCB, DISPATCH_LEVEL);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
} else {
//
// No SYN, just toss the frame.
//
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
return IP_PROTOCOL_NONE;
}
}
RcvTCB->tcb_refcnt++;
NotSYNSent:
//
// Not in the SYN-SENT state. Check the sequence number. If my window
// is 0, I'll truncate all incoming frames but look at some of the
// control fields. Otherwise I'll try and make this segment fit into
// the window.
//
if (RcvTCB->tcb_rcvwin != 0) {
int StateSize; // Size, including state info.
SeqNum LastValidSeq; // Sequence number of last valid byte at RWE.
//
// We are offering a window. If this segment starts in front of my
// receive window, clip off the front part.
//
if (SEQ_LT(RcvInfo.tri_seq, RcvTCB->tcb_rcvnext)) {
int AmountToClip, FinByte;
if (RcvInfo.tri_flags & TCP_FLAG_SYN) {
//
// Had a SYN. Clip it off and update the sequence number.
//
RcvInfo.tri_flags &= ~TCP_FLAG_SYN;
RcvInfo.tri_seq++;
RcvInfo.tri_urgent--;
}
//
// Advance the receive buffer to point at the new data.
//
AmountToClip = RcvTCB->tcb_rcvnext - RcvInfo.tri_seq;
ASSERT(AmountToClip >= 0);
//
// If there's a FIN on this segment, account for it.
//
FinByte = ((RcvInfo.tri_flags & TCP_FLAG_FIN) ? 1: 0);
if (AmountToClip >= (((int) Size) + FinByte)) {
//
// Falls entirely before the window. We have more special
// case code here - if the ack number acks something,
// we'll go ahead and take it, faking the sequence number
// to be rcvnext. This prevents problems on full duplex
// connections, where data has been received but not acked,
// and retransmission timers reset the seq number to
// below our rcvnext.
//
if ((RcvInfo.tri_flags & TCP_FLAG_ACK) &&
SEQ_LT(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LTE(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
//
// This contains valid ACK info. Fudge the information
// to get through the rest of this.
//
Size = 0;
AmountToClip = 0;
RcvInfo.tri_seq = RcvTCB->tcb_rcvnext;
RcvInfo.tri_flags &= ~(TCP_FLAG_SYN | TCP_FLAG_FIN |
TCP_FLAG_RST | TCP_FLAG_URG);
#if DBG
FinByte = 1; // Fake out assert below.
#endif
} else {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
}
//
// Trim what we have to. If we can't trim enough, the frame
// is too short. This shouldn't happen, but it it does we'll
// drop the frame.
//
Size -= AmountToClip;
RcvInfo.tri_seq += AmountToClip;
RcvInfo.tri_urgent -= AmountToClip;
Packet = TrimPacket(Packet, AmountToClip);
if (*(int *)&RcvInfo.tri_urgent < 0) {
RcvInfo.tri_urgent = 0;
RcvInfo.tri_flags &= ~TCP_FLAG_URG;
}
}
//
// We've made sure the front is OK. Now make sure part of it
// doesn't fall after the window. If it does, we'll truncate the
// frame (removing the FIN, if any). If we truncate the whole
// frame we'll ACKAndDrop it.
//
StateSize = Size + ((RcvInfo.tri_flags & TCP_FLAG_SYN) ? 1: 0) +
((RcvInfo.tri_flags & TCP_FLAG_FIN) ? 1: 0);
if (StateSize)
StateSize--;
//
// Now the incoming sequence number (RcvInfo.tri_seq) + StateSize
// it the last sequence number in the segment. If this is greater
// than the last valid byte in the window, we have some overlap
// to chop off.
//
ASSERT(StateSize >= 0);
LastValidSeq = RcvTCB->tcb_rcvnext + RcvTCB->tcb_rcvwin - 1;
if (SEQ_GT(RcvInfo.tri_seq + StateSize, LastValidSeq)) {
int AmountToChop;
//
// At least some part of the frame is outside of our window.
// See if it starts outside our window.
//
if (SEQ_GT(RcvInfo.tri_seq, LastValidSeq)) {
//
// Falls entirely outside the window. We have special
// case code to deal with a pure ack that falls exactly at
// our right window edge. Otherwise we ack and drop it.
//
if (!SEQ_EQ(RcvInfo.tri_seq, LastValidSeq+1) || Size != 0
|| (RcvInfo.tri_flags & (TCP_FLAG_SYN | TCP_FLAG_FIN))) {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
} else {
//
// At least some part of it is in the window. If there's a
// FIN, chop that off and see if that moves us inside.
//
if (RcvInfo.tri_flags & TCP_FLAG_FIN) {
RcvInfo.tri_flags &= ~TCP_FLAG_FIN;
StateSize--;
}
//
// Now figure out how much to chop off.
//
AmountToChop = (RcvInfo.tri_seq + StateSize) - LastValidSeq;
ASSERT(AmountToChop >= 0);
Size -= AmountToChop;
}
}
} else {
if (!SEQ_EQ(RcvTCB->tcb_rcvnext, RcvInfo.tri_seq)) {
//
// If there's a RST on this segment, and he's only off by 1,
// take it anyway. This can happen if the remote peer is
// probing and sends with the seq number after the probe.
//
if (!(RcvInfo.tri_flags & TCP_FLAG_RST) ||
!(SEQ_EQ(RcvTCB->tcb_rcvnext, (RcvInfo.tri_seq - 1)))) {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
} else
RcvInfo.tri_seq = RcvTCB->tcb_rcvnext;
}
//
// He's in sequence, but we have a window of 0. Truncate the
// size, and clear any sequence consuming bits.
//
if (Size != 0 || (RcvInfo.tri_flags &
(TCP_FLAG_SYN | TCP_FLAG_FIN))) {
RcvInfo.tri_flags &= ~(TCP_FLAG_SYN | TCP_FLAG_FIN);
Size = 0;
if (!(RcvInfo.tri_flags & TCP_FLAG_RST))
DelayAction(RcvTCB, NEED_ACK);
}
}
//
// At this point, the segment is in our window and does not overlap
// on either end. If it's the next sequence number we expect, we can
// handle the data now. Otherwise we'll queue it for later. In either
// case we'll handle RST and ACK information right now.
//
ASSERT((*(int *)&Size) >= 0);
//
// Now, following 793, we check the RST bit.
//
if (RcvInfo.tri_flags & TCP_FLAG_RST) {
uchar Reason;
//
// We can't go back into the LISTEN state from SYN-RCVD here,
// because we may have notified the client via a listen completing
// or a connect indication. So, if came from an active open we'll
// give back a 'connection refused' notice. For all other cases
// we'll just destroy the connection.
//
if (RcvTCB->tcb_state == TCB_SYN_RCVD) {
if (RcvTCB->tcb_flags & ACTIVE_OPEN)
Reason = TCB_CLOSE_REFUSED;
else
Reason = TCB_CLOSE_RST;
} else
Reason = TCB_CLOSE_RST;
TryToCloseTCB(RcvTCB, Reason, DISPATCH_LEVEL);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
if (RcvTCB->tcb_state != TCB_TIME_WAIT) {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
RemoveTCBFromConn(RcvTCB);
NotifyOfDisc(RcvTCB, TDI_CONNECTION_RESET);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
//
// Next check the SYN bit.
//
if (RcvInfo.tri_flags & TCP_FLAG_SYN) {
//
// Again, we can't quietly go back into the LISTEN state here, even
// if we came from a passive open.
//
TryToCloseTCB(RcvTCB, TCB_CLOSE_ABORTED, DISPATCH_LEVEL);
SendRSTFromHeader(TCP, Size, Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
if (RcvTCB->tcb_state != TCB_TIME_WAIT) {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
RemoveTCBFromConn(RcvTCB);
NotifyOfDisc(RcvTCB, TDI_CONNECTION_RESET);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
//
// Check the ACK field. If it's not on drop the segment.
//
if (RcvInfo.tri_flags & TCP_FLAG_ACK) {
uint UpdateWindow;
//
// If we're in SYN-RCVD, go to ESTABLISHED.
//
if (RcvTCB->tcb_state == TCB_SYN_RCVD) {
if (SEQ_LT(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LTE(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
//
// The ack is valid.
//
if (SynAttackProtect) {
//
// If we have not yet indicated this
// Connection to upper layer, do it now.
//
if (RcvTCB->tcb_flags & ACCEPT_PENDING) {
AddrObj *AO;
BOOLEAN Status=FALSE;
//
// We already have a refcnt on this TCB.
//
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
//
// Check if we still have the listening endpoint.
//
KeAcquireSpinLockAtDpcLevel(&AddrObjTableLock);
AO = GetBestAddrObj(AlignAddr(&Packet->IP->Dest),
DestScopeId, TCP->tcp_dest,
IP_PROTOCOL_TCP, NTE->IF);
if (AO != NULL) {
Status = DelayedAcceptConn(AO,Packet->SrcAddr,
SrcScopeId, TCP->tcp_src,RcvTCB);
} else {
KeReleaseSpinLockFromDpcLevel(&AddrObjTableLock);
}
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
if (!Status) {
//
// Delayed Accepance failed. Send RST.
//
RcvTCB->tcb_refcnt--;
TryToCloseTCB(RcvTCB, TCB_CLOSE_REFUSED, DISPATCH_LEVEL);
SendRSTFromHeader(TCP, Packet->TotalSize,
Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
return IP_SUCCESS;
} else {
RcvTCB->tcb_flags &= ~ACCEPT_PENDING;
}
}
}
RcvTCB->tcb_rexmitcnt = 0;
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
RcvTCB->tcb_senduna++;
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_maxwin = RcvInfo.tri_window;
RcvTCB->tcb_sendwl1 = RcvInfo.tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo.tri_ack;
GoToEstab(RcvTCB);
//
// We know our peer received our SYN.
//
if (RcvTCB->tcb_rce != NULL)
ConfirmForwardReachability(RcvTCB->tcb_rce);
//
// Now complete whatever we can here.
//
CompleteConnReq(RcvTCB, TDI_SUCCESS);
} else {
DerefTCB(RcvTCB, DISPATCH_LEVEL);
SendRSTFromHeader(TCP, Size, Packet->SrcAddr, SrcScopeId,
AlignAddr(&Packet->IP->Dest), DestScopeId);
return IP_PROTOCOL_NONE;
}
} else {
//
// We're not in SYN-RCVD. See if this acknowledges anything.
//
if (SEQ_LT(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LTE(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
uint CWin;
//
// The ack acknowledes something. Pull the
// appropriate amount off the send q.
//
ACKData(RcvTCB, RcvInfo.tri_ack);
//
// If this acknowledges something we were running a RTT on,
// update that stuff now.
//
if (RcvTCB->tcb_rtt != 0 && SEQ_GT(RcvInfo.tri_ack,
RcvTCB->tcb_rttseq)) {
short RTT;
RTT = (short)(TCPTime - RcvTCB->tcb_rtt);
RcvTCB->tcb_rtt = 0;
RTT -= (RcvTCB->tcb_smrtt >> 3);
RcvTCB->tcb_smrtt += RTT;
RTT = (RTT >= 0 ? RTT : -RTT);
RTT -= (RcvTCB->tcb_delta >> 3);
RcvTCB->tcb_delta += RTT + RTT;
RcvTCB->tcb_rexmit = MIN(MAX(REXMIT_TO(RcvTCB),
MIN_RETRAN_TICKS),
MAX_REXMIT_TO);
}
//
// If we're probing for a PMTU black hole then we've found
// one, so turn off the detection. The size is already
// down, so leave it there.
//
if (RcvTCB->tcb_flags & PMTU_BH_PROBE) {
RcvTCB->tcb_flags &= ~PMTU_BH_PROBE;
RcvTCB->tcb_bhprobecnt = 0;
if (--(RcvTCB->tcb_slowcount) == 0) {
RcvTCB->tcb_fastchk &= ~TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
}
if ((RcvTCB->tcb_dupacks >= MaxDupAcks) &&
((int)RcvTCB->tcb_ssthresh > 0)) {
//
// We were in fast retransmit mode, so this ACK is for
// our fast retransmitted frame. Set cwin to ssthresh
// so that cwin grows linearly from here.
//
RcvTCB->tcb_cwin = RcvTCB->tcb_ssthresh;
} else {
//
// Update the congestion window now.
//
CWin = RcvTCB->tcb_cwin;
if (CWin < RcvTCB->tcb_maxwin) {
if (CWin < RcvTCB->tcb_ssthresh)
CWin += RcvTCB->tcb_mss;
else
CWin += (RcvTCB->tcb_mss * RcvTCB->tcb_mss)/CWin;
RcvTCB->tcb_cwin = MIN(CWin, RcvTCB->tcb_maxwin);
}
}
ASSERT(*(int *)&RcvTCB->tcb_cwin > 0);
//
// Since this isn't a duplicate ACK, reset the counter.
//
RcvTCB->tcb_dupacks = 0;
//
// We've acknowledged something, so reset the rexmit count.
// If there's still stuff outstanding, restart the rexmit
// timer.
//
RcvTCB->tcb_rexmitcnt = 0;
if (!SEQ_EQ(RcvInfo.tri_ack, RcvTCB->tcb_sendmax))
START_TCB_TIMER(RcvTCB->tcb_rexmittimer,
RcvTCB->tcb_rexmit);
else
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
//
// If we've sent a FIN, and this acknowledges it, we
// need to complete the client's close request and
// possibly transition our state.
//
if (RcvTCB->tcb_flags & FIN_SENT) {
//
// We have sent a FIN. See if it's been acknowledged.
// Once we've sent a FIN, tcb_sendmax can't advance,
// so our FIN must have sequence num tcb_sendmax - 1.
// Thus our FIN is acknowledged if the incoming ack is
// equal to tcb_sendmax.
//
if (SEQ_EQ(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
//
// He's acked our FIN. Turn off the flags,
// and complete the request. We'll leave the
// FIN_OUTSTANDING flag alone, to force early
// outs in the send code.
//
RcvTCB->tcb_flags &= ~(FIN_NEEDED | FIN_SENT);
ASSERT(RcvTCB->tcb_unacked == 0);
ASSERT(RcvTCB->tcb_sendnext == RcvTCB->tcb_sendmax);
//
// Now figure out what we need to do. In FIN_WAIT1
// or FIN_WAIT, just complete the disconnect
// request and continue. Otherwise, it's a bit
// trickier, since we can't complete the connreq
// until we remove the TCB from it's connection.
//
switch (RcvTCB->tcb_state) {
case TCB_FIN_WAIT1:
RcvTCB->tcb_state = TCB_FIN_WAIT2;
CompleteConnReq(RcvTCB, TDI_SUCCESS);
//
// Start a timer in case we never get
// out of FIN_WAIT2. Set the retransmit
// count high to force a timeout the
// first time the timer fires.
//
RcvTCB->tcb_rexmitcnt = (uchar)MaxDataRexmitCount;
START_TCB_TIMER(RcvTCB->tcb_rexmittimer,
(ushort)FinWait2TO);
// Fall through to FIN-WAIT-2 processing.
case TCB_FIN_WAIT2:
break;
case TCB_CLOSING:
GracefulClose(RcvTCB, TRUE, FALSE, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
break;
case TCB_LAST_ACK:
GracefulClose(RcvTCB, FALSE, FALSE,
DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
break;
default:
KdBreakPoint();
break;
}
}
}
UpdateWindow = TRUE;
} else {
//
// It doesn't ack anything. If we're in FIN_WAIT2,
// we'll restart the timer. We don't make this check
// above because we know no data can be acked when we're
// in FIN_WAIT2.
//
if (RcvTCB->tcb_state == TCB_FIN_WAIT2)
START_TCB_TIMER(RcvTCB->tcb_rexmittimer, (ushort)FinWait2TO);
//
// If it's an ack for something larger than
// we've sent then ACKAndDrop it.
//
if (SEQ_GT(RcvInfo.tri_ack, RcvTCB->tcb_sendmax)) {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
//
// If it is a pure duplicate ack, check if we should
// do a fast retransmit.
//
if ((Size == 0) &&
SEQ_EQ(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
SEQ_LT(RcvTCB->tcb_senduna, RcvTCB->tcb_sendmax) &&
(RcvTCB->tcb_sendwin == RcvInfo.tri_window) &&
RcvInfo.tri_window) {
//
// See if fast rexmit can be done.
//
if (HandleFastXmit(RcvTCB, &RcvInfo)) {
return IP_PROTOCOL_NONE;
}
} else {
//
// Not a pure duplicate ack (Size != 0 or peer is
// advertising a new window). Reset counter.
//
RcvTCB->tcb_dupacks = 0;
//
// See if we should update the window.
//
if (SEQ_EQ(RcvTCB->tcb_senduna, RcvInfo.tri_ack) &&
(SEQ_LT(RcvTCB->tcb_sendwl1, RcvInfo.tri_seq) ||
(SEQ_EQ(RcvTCB->tcb_sendwl1, RcvInfo.tri_seq) &&
SEQ_LTE(RcvTCB->tcb_sendwl2, RcvInfo.tri_ack)))){
UpdateWindow = TRUE;
} else
UpdateWindow = FALSE;
}
}
if (UpdateWindow) {
RcvTCB->tcb_sendwin = RcvInfo.tri_window;
RcvTCB->tcb_maxwin = MAX(RcvTCB->tcb_maxwin,
RcvInfo.tri_window);
RcvTCB->tcb_sendwl1 = RcvInfo.tri_seq;
RcvTCB->tcb_sendwl2 = RcvInfo.tri_ack;
if (RcvInfo.tri_window == 0) {
//
// We've got a zero window.
//
if (!EMPTYQ(&RcvTCB->tcb_sendq)) {
RcvTCB->tcb_flags &= ~NEED_OUTPUT;
RcvTCB->tcb_rexmitcnt = 0;
START_TCB_TIMER(RcvTCB->tcb_rexmittimer,
RcvTCB->tcb_rexmit);
if (!(RcvTCB->tcb_flags & FLOW_CNTLD)) {
RcvTCB->tcb_flags |= FLOW_CNTLD;
RcvTCB->tcb_slowcount++;
RcvTCB->tcb_fastchk |= TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
}
} else {
if (RcvTCB->tcb_flags & FLOW_CNTLD) {
RcvTCB->tcb_rexmitcnt = 0;
RcvTCB->tcb_flags &= ~(FLOW_CNTLD | FORCE_OUTPUT);
//
// Reset send next to the left edge of the window,
// because it might be at senduna+1 if we've been
// probing.
//
ResetSendNext(RcvTCB, RcvTCB->tcb_senduna);
if (--(RcvTCB->tcb_slowcount) == 0) {
RcvTCB->tcb_fastchk &= ~TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
}
//
// Since we've updated the window, see if we can send
// some more.
//
if (RcvTCB->tcb_unacked != 0 ||
(RcvTCB->tcb_flags & FIN_NEEDED))
DelayAction(RcvTCB, NEED_OUTPUT);
}
}
}
//
// We've handled all the acknowledgment stuff. If the size
// is greater than 0 or important bits are set process it further,
// otherwise it's a pure ack and we're done with it.
//
if (Size > 0 || (RcvInfo.tri_flags & TCP_FLAG_FIN)) {
//
// If we're not in a state where we can process incoming data
// or FINs, there's no point in going further. Just send an
// ack and drop this segment.
//
if (!DATA_RCV_STATE(RcvTCB->tcb_state) ||
(RcvTCB->tcb_flags & GC_PENDING)) {
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
//
// If our peer is sending into an expanded window, then our
// peer must have received our ACK advertising said window.
// Take this as proof of forward reachability.
// Note: we have no guarantee this is timely.
//
if (SEQ_GTE(RcvInfo.tri_seq + (int)Size,
RcvTCB->tcb_rcvwinwatch)) {
RcvTCB->tcb_rcvwinwatch = RcvTCB->tcb_rcvnext +
RcvTCB->tcb_rcvwin;
if (RcvTCB->tcb_rce != NULL)
ConfirmForwardReachability(RcvTCB->tcb_rce);
}
//
// If it's in sequence process it now, otherwise reassemble it.
//
if (SEQ_EQ(RcvInfo.tri_seq, RcvTCB->tcb_rcvnext)) {
//
// If we're already in the receive handler, this is a
// duplicate. We'll just toss it.
//
if (RcvTCB->tcb_fastchk & TCP_FLAG_IN_RCV) {
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
RcvTCB->tcb_fastchk |= TCP_FLAG_IN_RCV;
//
// Now loop, pulling things from the reassembly queue,
// until the queue is empty, or we can't take all of the
// data, or we hit a FIN.
//
do {
//
// Handle urgent data, if any.
//
if (RcvInfo.tri_flags & TCP_FLAG_URG) {
HandleUrgent(RcvTCB, &RcvInfo, Packet, &Size);
//
// Since we may have freed the lock, we need to
// recheck and see if we're closing here.
//
if (CLOSING(RcvTCB))
break;
}
//
// OK, the data is in sequence, we've updated the
// reassembly queue and handled any urgent data. If we
// have any data go ahead and process it now.
//
if (Size > 0) {
BytesTaken = (*RcvTCB->tcb_rcvhndlr)
(RcvTCB, RcvInfo.tri_flags, Packet, Size);
RcvTCB->tcb_rcvnext += BytesTaken;
RcvTCB->tcb_rcvwin -= BytesTaken;
CheckTCBRcv(RcvTCB);
if (RcvTCB->tcb_flags & ACK_DELAYED)
DelayAction(RcvTCB, NEED_ACK);
else {
RcvTCB->tcb_flags |= ACK_DELAYED;
START_TCB_TIMER(RcvTCB->tcb_delacktimer,
DEL_ACK_TICKS);
}
if (BytesTaken != Size) {
//
// We didn't take everything we could. No
// use in further processing, just bail
// out.
//
DelayAction(RcvTCB, NEED_ACK);
break;
}
//
// If we're closing now, we're done, so get out.
//
if (CLOSING(RcvTCB))
break;
}
//
// See if we need to advance over some urgent data.
//
if (RcvTCB->tcb_flags & URG_VALID) {
uint AdvanceNeeded;
//
// We only need to advance if we're not doing
// urgent inline. Urgent inline also has some
// implications for when we can clear the URG_VALID
// flag. If we're not doing urgent inline, we can
// clear it when rcvnext advances beyond urgent
// end. If we are doing urgent inline, we clear it
// when rcvnext advances one receive window beyond
// urgend.
//
if (!(RcvTCB->tcb_flags & URG_INLINE)) {
if (RcvTCB->tcb_rcvnext == RcvTCB->tcb_urgstart) {
RcvTCB->tcb_rcvnext = RcvTCB->tcb_urgend + 1;
} else {
ASSERT(SEQ_LT(RcvTCB->tcb_rcvnext,
RcvTCB->tcb_urgstart) ||
SEQ_GT(RcvTCB->tcb_rcvnext,
RcvTCB->tcb_urgend));
}
AdvanceNeeded = 0;
} else
AdvanceNeeded = RcvTCB->tcb_defaultwin;
//
// See if we can clear the URG_VALID flag.
//
if (SEQ_GT(RcvTCB->tcb_rcvnext - AdvanceNeeded,
RcvTCB->tcb_urgend)) {
RcvTCB->tcb_flags &= ~URG_VALID;
if (--(RcvTCB->tcb_slowcount) == 0) {
RcvTCB->tcb_fastchk &= ~TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
}
}
}
//
// We've handled the data. If the FIN bit is set, we
// have more processing.
//
if (RcvInfo.tri_flags & TCP_FLAG_FIN) {
uint Notify = FALSE;
RcvTCB->tcb_rcvnext++;
DelayAction(RcvTCB, NEED_ACK);
PushData(RcvTCB);
switch (RcvTCB->tcb_state) {
case TCB_SYN_RCVD:
//
// I don't think we can get here - we
// should have discarded the frame if it
// had no ACK, or gone to established if
// it did.
//
KdBreakPoint();
case TCB_ESTAB:
RcvTCB->tcb_state = TCB_CLOSE_WAIT;
//
// We left established, we're off the
// fast path.
//
RcvTCB->tcb_slowcount++;
RcvTCB->tcb_fastchk |= TCP_FLAG_SLOW;
CheckTCBRcv(RcvTCB);
Notify = TRUE;
break;
case TCB_FIN_WAIT1:
RcvTCB->tcb_state = TCB_CLOSING;
Notify = TRUE;
break;
case TCB_FIN_WAIT2:
//
// Stop the FIN_WAIT2 timer.
//
STOP_TCB_TIMER(RcvTCB->tcb_rexmittimer);
RcvTCB->tcb_refcnt++;
GracefulClose(RcvTCB, TRUE, TRUE, DISPATCH_LEVEL);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
break;
default:
KdBreakPoint();
break;
}
if (Notify) {
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
NotifyOfDisc(RcvTCB, TDI_GRACEFUL_DISC);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
}
break; // Exit out of WHILE loop.
}
//
// If the reassembly queue isn't empty, get what we
// can now.
//
Packet = PullFromRAQ(RcvTCB, &RcvInfo, &Size);
CheckPacketList(Packet, Size);
} while (Packet != NULL);
RcvTCB->tcb_fastchk &= ~TCP_FLAG_IN_RCV;
if (RcvTCB->tcb_flags & SEND_AFTER_RCV) {
RcvTCB->tcb_flags &= ~SEND_AFTER_RCV;
DelayAction(RcvTCB, NEED_OUTPUT);
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
} else {
//
// It's not in sequence. Since it needs further
// processing, put in on the reassembly queue.
//
if (DATA_RCV_STATE(RcvTCB->tcb_state) &&
!(RcvTCB->tcb_flags & GC_PENDING)) {
PutOnRAQ(RcvTCB, &RcvInfo, Packet, Size);
KeReleaseSpinLockFromDpcLevel(&RcvTCB->tcb_lock);
SendACK(RcvTCB);
KeAcquireSpinLockAtDpcLevel(&RcvTCB->tcb_lock);
DerefTCB(RcvTCB, DISPATCH_LEVEL);
} else
ACKAndDrop(&RcvInfo, RcvTCB);
return IP_PROTOCOL_NONE;
}
}
} else {
//
// No ACK. Just drop the segment and return.
//
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
DerefTCB(RcvTCB, DISPATCH_LEVEL);
return IP_PROTOCOL_NONE;
}
//* TCPControlReceive - handler for TCP control messages.
//
// This routine is called if we receive an ICMPv6 error message that
// was generated by some remote site as a result of receiving a TCP
// packet from us.
//
uchar
TCPControlReceive(
IPv6Packet *Packet, // Packet handed to us by ICMPv6ErrorReceive.
StatusArg *StatArg) // Error Code, Argument, and invoking IP header.
{
KIRQL Irql0, Irql1; // One per lock nesting level.
TCB *StatusTCB;
SeqNum DropSeq;
TCPHeader UNALIGNED *InvokingTCP;
Interface *IF = Packet->NTEorIF->IF;
uint SrcScopeId, DestScopeId;
//
// The next thing in the packet should be the TCP header of the
// original packet which invoked this error.
//
if (! PacketPullup(Packet, sizeof(TCPHeader), 1, 0)) {
// Pullup failed.
if (Packet->TotalSize < sizeof(TCPHeader))
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_BAD_PACKET,
"TCPv6: Packet too small to contain TCP header "
"from invoking packet\n"));
return IP_PROTOCOL_NONE; // Drop packet.
}
InvokingTCP = (TCPHeader UNALIGNED *)Packet->Data;
//
// Determining the scope identifiers for the addresses in the
// invoking packet is potentially problematic, since we have
// no way to be certain which interface we sent the packet on.
// Use the interface the icmp error arrived on to determine
// the scope ids for both the local and remote addresses.
//
SrcScopeId = DetermineScopeId(AlignAddr(&StatArg->IP->Source), IF);
DestScopeId = DetermineScopeId(AlignAddr(&StatArg->IP->Dest), IF);
//
// Find the TCB for the connection this packet was sent on.
//
KeAcquireSpinLock(&TCBTableLock, &Irql0);
StatusTCB = FindTCB(AlignAddr(&StatArg->IP->Source),
AlignAddr(&StatArg->IP->Dest),
SrcScopeId, DestScopeId,
InvokingTCP->tcp_src, InvokingTCP->tcp_dest);
if (StatusTCB != NULL) {
//
// Found one. Get the lock on it, and continue.
//
CHECK_STRUCT(StatusTCB, tcb);
KeAcquireSpinLock(&StatusTCB->tcb_lock, &Irql1);
KeReleaseSpinLock(&TCBTableLock, Irql1);
//
// Make sure the TCB is in a state that is interesting.
//
// We also drop packets for TCBs where we don't already have
// an RCE, since any ICMP errors we get for packets we haven't
// sent are likely to be spoofed.
//
if (StatusTCB->tcb_state == TCB_CLOSED ||
StatusTCB->tcb_state == TCB_TIME_WAIT ||
CLOSING(StatusTCB) ||
StatusTCB->tcb_rce == NULL) {
//
// Connection is already closing, or too new to have sent
// anything yet. Leave it be.
//
KeReleaseSpinLock(&StatusTCB->tcb_lock, Irql0);
return IP_PROTOCOL_NONE; // Discard error packet.
}
switch (StatArg->Status) {
case IP_UNRECOGNIZED_NEXT_HEADER:
//
// Destination protocol unreachable.
// We treat this as a fatal errors. Close the connection.
//
StatusTCB->tcb_error = StatArg->Status;
StatusTCB->tcb_refcnt++;
TryToCloseTCB(StatusTCB, TCB_CLOSE_UNREACH, Irql0);
RemoveTCBFromConn(StatusTCB);
NotifyOfDisc(StatusTCB,
MapIPError(StatArg->Status, TDI_DEST_UNREACHABLE));
KeAcquireSpinLock(&StatusTCB->tcb_lock, &Irql1);
DerefTCB(StatusTCB, Irql1);
return IP_PROTOCOL_NONE; // Done with packet.
break;
case IP_DEST_NO_ROUTE:
case IP_DEST_ADDR_UNREACHABLE:
case IP_DEST_PORT_UNREACHABLE:
case IP_DEST_PROHIBITED:
case IP_BAD_ROUTE:
case IP_HOP_LIMIT_EXCEEDED:
case IP_REASSEMBLY_TIME_EXCEEDED:
case IP_PARAMETER_PROBLEM:
//
// Soft errors. Save the error in case it times out.
//
StatusTCB->tcb_error = StatArg->Status;
break;
case IP_PACKET_TOO_BIG: {
uint PMTU;
IF_TCPDBG(TCP_DEBUG_MSS) {
KdPrintEx((DPFLTR_TCPIP6_ID, DPFLTR_INFO_TCPDBG,
"TCPControlReceive: Got Packet Too Big\n"));
}
//
// We sent a TCP datagram which was too big for the path to
// our destination. That packet was dropped by the router
// which sent us this error message. The Arg value is TRUE
// if this Packet Too Big reduced our PMTU, FALSE otherwise.
//
if (!StatArg->Arg)
break;
//
// Our PMTU was reduced. Find out what it is now.
//
PMTU = GetEffectivePathMTUFromRCE(StatusTCB->tcb_rce);
//
// Update fields based on new PMTU.
//
StatusTCB->tcb_pmtu = PMTU;
StatusTCB->tcb_security = SecurityStateValidationCounter;
CalculateMSSForTCB(StatusTCB);
//
// Since our PMTU was reduced, we know that this is the first
// Packet Too Big we've received about this bottleneck.
// We should retransmit so long as this is for a legitimate
// outstanding packet (i.e. sequence number is is greater than
// the last acked and less than our current send next).
//
DropSeq = net_long(InvokingTCP->tcp_seq);
if ((SEQ_GTE(DropSeq, StatusTCB->tcb_senduna) &&
SEQ_LT(DropSeq, StatusTCB->tcb_sendnext))) {
//
// Need to initiate a retransmit.
//
ResetSendNext(StatusTCB, DropSeq);
//
// WINBUG #242757 11-27-2000 richdr TCP resp. to Packet Too Big
// RFC 1981 states that "a retransmission caused by a Packet
// Too Big message should not change the congestion window.
// It should, however, trigger the slow-start mechanism."
// The code below would appear to be broken. However, the
// IPv4 stack works this way.
//
//
// Set the congestion window to allow only one packet.
// This may prevent us from sending anything if we
// didn't just set sendnext to senduna. This is OK,
// we'll retransmit later, or send when we get an ack.
//
StatusTCB->tcb_cwin = StatusTCB->tcb_mss;
DelayAction(StatusTCB, NEED_OUTPUT);
}
}
break;
default:
// Should never happen.
KdBreakPoint();
break;
}
KeReleaseSpinLock(&StatusTCB->tcb_lock, Irql0);
} else {
//
// Couldn't find a matching TCB. Connection probably went away since
// we sent the offending packet. Just free the lock and return.
//
KeReleaseSpinLock(&TCBTableLock, Irql0);
}
return IP_PROTOCOL_NONE; // Done with packet.
}
#pragma BEGIN_INIT
//* InitTCPRcv - Initialize TCP receive side.
//
// Called during init time to initialize our TCP receive side.
//
int // Returns: TRUE.
InitTCPRcv(
void) // Nothing.
{
ExInitializeSListHead(&TCPRcvReqFree);
KeInitializeSpinLock(&RequestCompleteLock);
KeInitializeSpinLock(&TCBDelayLock);
KeInitializeSpinLock(&TCPRcvReqFreeLock);
INITQ(&ConnRequestCompleteQ);
INITQ(&SendCompleteQ);
INITQ(&TCBDelayQ);
RequestCompleteFlags = 0;
TCBDelayRtnCount = 0;
TCBDelayRtnLimit = (uint) KeNumberProcessors;
if (TCBDelayRtnLimit > TCB_DELAY_RTN_LIMIT)
TCBDelayRtnLimit = TCB_DELAY_RTN_LIMIT;
RtlZeroMemory(&DummyPacket, sizeof DummyPacket);
DummyPacket.Flags = PACKET_OURS;
return TRUE;
}
#pragma END_INIT
//* UnloadTCPRcv
//
// Cleanup and prepare for stack unload.
//
void
UnloadTCPRcv(void)
{
PSLIST_ENTRY BufferLink;
while ((BufferLink = ExInterlockedPopEntrySList(&TCPRcvReqFree,
&TCPRcvReqFreeLock))
!= NULL) {
TCPRcvReq *RcvReq = CONTAINING_RECORD(BufferLink, TCPRcvReq, trr_next);
CHECK_STRUCT(RcvReq, trr);
ExFreePool(RcvReq);
}
}
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