tcp4timer.c

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/*++

Copyright (c) 2005 - 2006, Intel Corporation                                                         
All rights reserved. This program and the accompanying materials                          
are licensed and made available under the terms and conditions of the BSD License         
which accompanies this distribution.  The full text of the license may be found at        
http://opensource.org/licenses/bsd-license.php                                            
                                                                                          
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 

Module Name:

  Tcp4Timer.c

Abstract:

  TCP timer related functions.

--*/

#include "Tcp4Main.h"

UINT32    mTcpTick = 1000;

STATIC
VOID
TcpConnectTimeout (
  IN TCP_CB *Tcb
  );

STATIC
VOID
TcpRexmitTimeout (
  IN TCP_CB *Tcb
  );

STATIC
VOID
TcpProbeTimeout (
  IN TCP_CB *Tcb
  );

STATIC
VOID
TcpKeepaliveTimeout (
  IN TCP_CB *Tcb
  );

STATIC
VOID
TcpFinwait2Timeout (
  IN TCP_CB *Tcb
  );

STATIC
VOID
Tcp2MSLTimeout (
  IN TCP_CB *Tcb
  );

TCP_TIMER_HANDLER mTcpTimerHandler[TCP_TIMER_NUMBER] = {
  TcpConnectTimeout,
  TcpRexmitTimeout,
  TcpProbeTimeout,
  TcpKeepaliveTimeout,
  TcpFinwait2Timeout,
  Tcp2MSLTimeout,
};

VOID
TcpClose (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Close the TCP connection.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  NetbufFreeList (&Tcb->SndQue);
  NetbufFreeList (&Tcb->RcvQue);

  TcpSetState (Tcb, TCP_CLOSED);
}

STATIC
VOID
TcpConnectTimeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Connect timeout handler.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  if (!TCP_CONNECTED (Tcb->State)) {
    TCP4_DEBUG_ERROR (("TcpConnectTimeout: connection closed "
      "because conenction timer timeout for TCB %x\n", Tcb));

    if (EFI_ABORTED == Tcb->Sk->SockError) {
      SOCK_ERROR (Tcb->Sk, EFI_TIMEOUT);
    }

    if (TCP_SYN_RCVD == Tcb->State) {
      TCP4_DEBUG_WARN (("TcpConnectTimeout: send reset because "
        "connection timer timeout for TCB %x\n", Tcb));

      TcpResetConnection (Tcb);

    }

    TcpClose (Tcb);
  }
}

STATIC
VOID
TcpRexmitTimeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Timeout handler for TCP retransmission timer.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  UINT32  FlightSize;

  TCP4_DEBUG_WARN (("TcpRexmitTimeout: transmission "
    "timeout for TCB %x\n", Tcb));

  //
  // Set the congestion window. FlightSize is the
  // amount of data that has been sent but not
  // yet ACKed.
  //
  FlightSize        = TCP_SUB_SEQ (Tcb->SndNxt, Tcb->SndUna);
  Tcb->Ssthresh     = NET_MAX ((UINT32) (2 * Tcb->SndMss), FlightSize / 2);

  Tcb->CWnd         = Tcb->SndMss;
  Tcb->LossRecover  = Tcb->SndNxt;

  Tcb->LossTimes++;
  if (Tcb->LossTimes > Tcb->MaxRexmit &&
      !TCP_TIMER_ON (Tcb->EnabledTimer, TCP_TIMER_CONNECT)) {

    TCP4_DEBUG_ERROR (("TcpRexmitTimeout: connection closed "
      "because too many timeouts for TCB %x\n", Tcb));

    if (EFI_ABORTED == Tcb->Sk->SockError) {
      SOCK_ERROR (Tcb->Sk, EFI_TIMEOUT);
    }

    TcpClose (Tcb);
    return ;
  }

  TcpBackoffRto (Tcb);
  TcpRetransmit (Tcb, Tcb->SndUna);
  TcpSetTimer (Tcb, TCP_TIMER_REXMIT, Tcb->Rto);

  Tcb->CongestState = TCP_CONGEST_LOSS;

  TCP_CLEAR_FLG (Tcb->CtrlFlag, TCP_CTRL_RTT_ON);
}

STATIC
VOID
TcpProbeTimeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Timeout handler for window probe timer.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  //
  // This is the timer for sender's SWSA. RFC1122 requires
  // a timer set for sender's SWSA, and suggest combine it
  // with window probe timer. If data is sent, don't set
  // the probe timer, since retransmit timer is on.
  //
  if ((TcpDataToSend (Tcb, 1) != 0) && (TcpToSendData (Tcb, 1) > 0)) {

    ASSERT (TCP_TIMER_ON (Tcb->EnabledTimer, TCP_TIMER_REXMIT));
    return ;
  }

  TcpSendZeroProbe (Tcb);
  TcpSetProbeTimer (Tcb);
}

STATIC
VOID
TcpKeepaliveTimeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Timeout handler for keepalive timer.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  Tcb->KeepAliveProbes++;

  //
  // Too many Keep-alive probes, drop the connection
  //
  if (Tcb->KeepAliveProbes > Tcb->MaxKeepAlive) {

    if (EFI_ABORTED == Tcb->Sk->SockError) {
      SOCK_ERROR (Tcb->Sk, EFI_TIMEOUT);
    }

    TcpClose (Tcb);
    return ;
  }

  TcpSendZeroProbe (Tcb);
  TcpSetKeepaliveTimer (Tcb);
}

STATIC
VOID
TcpFinwait2Timeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Timeout handler for FIN_WAIT_2 timer.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  TCP4_DEBUG_WARN (("TcpFinwait2Timeout: connection closed "
    "because FIN_WAIT2 timer timeouts for TCB %x\n", Tcb));

  TcpClose (Tcb);
}

STATIC
VOID
Tcp2MSLTimeout (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Timeout handler for 2MSL timer.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  TCP4_DEBUG_WARN (("Tcp2MSLTimeout: connection closed "
    "because TIME_WAIT timer timeouts for TCB %x\n", Tcb));

  TcpClose (Tcb);
}

STATIC
VOID
TcpUpdateTimer (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Update the timer status and the next expire time
  according to the timers to expire in a specific
  future time slot.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  UINT16  Index;

  //
  // Don't use a too large value to init NextExpire
  // since mTcpTick wraps around as sequence no does.
  //
  Tcb->NextExpire = 65535;
  TCP_CLEAR_FLG (Tcb->CtrlFlag, TCP_CTRL_TIMER_ON);

  for (Index = 0; Index < TCP_TIMER_NUMBER; Index++) {

    if (TCP_TIMER_ON (Tcb->EnabledTimer, Index) &&
        TCP_TIME_LT (Tcb->Timer[Index], mTcpTick + Tcb->NextExpire)) {

      Tcb->NextExpire = TCP_SUB_TIME (Tcb->Timer[Index], mTcpTick);
      TCP_SET_FLG (Tcb->CtrlFlag, TCP_CTRL_TIMER_ON);
    }
  }
}

VOID
TcpSetTimer (
  IN TCP_CB *Tcb,
  IN UINT16 Timer,
  IN UINT32 TimeOut
  )
/*++

Routine Description:

  Enable a TCP timer.

Arguments:

  Tcb     - Pointer to the TCP_CB of this TCP instance.
  Timer   - The index of the timer to be enabled.
  TimeOut - The timeout value of this timer.

Returns:

  None.

--*/
{
  TCP_SET_TIMER (Tcb->EnabledTimer, Timer);
  Tcb->Timer[Timer] = mTcpTick + TimeOut;

  TcpUpdateTimer (Tcb);
}

VOID
TcpClearTimer (
  IN TCP_CB *Tcb,
  IN UINT16 Timer
  )
/*++

Routine Description:

  Clear one TCP timer.

Arguments:

  Tcb   - Pointer to the TCP_CB of this TCP instance.
  Timer - The index of the timer to be cleared.

Returns:

  None.

--*/
{
  TCP_CLEAR_TIMER (Tcb->EnabledTimer, Timer);
  TcpUpdateTimer (Tcb);
}

VOID
TcpClearAllTimer (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Clear all TCP timers.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  Tcb->EnabledTimer = 0;
  TcpUpdateTimer (Tcb);
}

VOID
TcpSetProbeTimer (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Enable the window prober timer and set the timeout value.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  if (!TCP_TIMER_ON (Tcb->EnabledTimer, TCP_TIMER_PROBE)) {
    Tcb->ProbeTime = Tcb->Rto;

  } else {
    Tcb->ProbeTime <<= 1;
  }

  if (Tcb->ProbeTime < TCP_RTO_MIN) {

    Tcb->ProbeTime = TCP_RTO_MIN;
  } else if (Tcb->ProbeTime > TCP_RTO_MAX) {

    Tcb->ProbeTime = TCP_RTO_MAX;
  }

  TcpSetTimer (Tcb, TCP_TIMER_PROBE, Tcb->ProbeTime);
}

VOID
TcpSetKeepaliveTimer (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Enable the keepalive timer and set the timeout value.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  if (TCP_FLG_ON (Tcb->CtrlFlag, TCP_CTRL_NO_KEEPALIVE)) {
    return ;

  }

  //
  // Set the timer to KeepAliveIdle if either
  // 1. the keepalive timer is off
  // 2. The keepalive timer is on, but the idle
  // is less than KeepAliveIdle, that means the
  // connection is alive since our last probe.
  //
  if (!TCP_TIMER_ON (Tcb->EnabledTimer, TCP_TIMER_KEEPALIVE) ||
      (Tcb->Idle < Tcb->KeepAliveIdle)) {

    TcpSetTimer (Tcb, TCP_TIMER_KEEPALIVE, Tcb->KeepAliveIdle);
    Tcb->KeepAliveProbes = 0;

  } else {

    TcpSetTimer (Tcb, TCP_TIMER_KEEPALIVE, Tcb->KeepAlivePeriod);
  }
}

VOID
TcpBackoffRto (
  IN TCP_CB *Tcb
  )
/*++

Routine Description:

  Backoff the RTO.

Arguments:

  Tcb - Pointer to the TCP_CB of this TCP instance.

Returns:

  None.

--*/
{
  //
  // Fold the RTT estimate if too many times, the estimate
  // may be wrong, fold it. So the next time a valid
  // measurement is sampled, we can start fresh.
  //
  if ((Tcb->LossTimes >= TCP_FOLD_RTT) && Tcb->SRtt) {
    Tcb->RttVar += Tcb->SRtt >> 2;
    Tcb->SRtt = 0;
  }

  Tcb->Rto <<= 1;

  if (Tcb->Rto < TCP_RTO_MIN) {

    Tcb->Rto = TCP_RTO_MIN;
  } else if (Tcb->Rto > TCP_RTO_MAX) {

    Tcb->Rto = TCP_RTO_MAX;
  }
}

VOID
EFIAPI
TcpTicking (
  IN EFI_EVENT Event,
  IN VOID      *Context
  )
/*++

Routine Description:

  Heart beat timer handler.

Arguments:

  Event   - Timer event signaled, ignored.
  Context - Context of the timer event, ignored.

Returns:

  None.

--*/
{
  NET_LIST_ENTRY  *Entry;
  NET_LIST_ENTRY  *Next;
  TCP_CB          *Tcb;
  INT16           Index;

  mTcpTick++;
  mTcpGlobalIss += 100;

  //
  // Don't use LIST_FOR_EACH, which isn't delete safe.
  //
  for (Entry = mTcpRunQue.ForwardLink; Entry != &mTcpRunQue; Entry = Next) {

    Next  = Entry->ForwardLink;

    Tcb   = NET_LIST_USER_STRUCT (Entry, TCP_CB, List);

    if (Tcb->State == TCP_CLOSED) {
      continue;
    }
    //
    // The connection is doing RTT measurement.
    //
    if (TCP_FLG_ON (Tcb->CtrlFlag, TCP_CTRL_RTT_ON)) {
      Tcb->RttMeasure++;
    }

    Tcb->Idle++;

    if (Tcb->DelayedAck) {
      TcpSendAck (Tcb);
    }

    //
    // No timer is active or no timer expired
    //
    if (!TCP_FLG_ON (Tcb->CtrlFlag, TCP_CTRL_TIMER_ON) ||
        ((--Tcb->NextExpire) > 0)) {

      continue;
    }

    //
    // Call the timeout handler for each expired timer.
    //
    for (Index = 0; Index < TCP_TIMER_NUMBER; Index++) {

      if (TCP_TIMER_ON (Tcb->EnabledTimer, Index) &&
          TCP_TIME_LEQ (Tcb->Timer[Index], mTcpTick)) {
        //
        // disable the timer before calling the handler
        // in case the handler enables it again.
        //
        TCP_CLEAR_TIMER (Tcb->EnabledTimer, Index);
        mTcpTimerHandler[Index](Tcb);

        //
        // The Tcb may have been deleted by the timer, or
        // no other timer is set.
        //
        if ((Next->BackLink != Entry) ||
            (Tcb->EnabledTimer == 0)) {

          goto NextConnection;
        }
      }
    }

    TcpUpdateTimer (Tcb);
NextConnection:
    ;
  }
}