Is socketbuffer empty?

  • Thread starter Thread starter Robert A. van Ginkel
  • Start date Start date
R

Robert A. van Ginkel

Hello Fellow Developer,

This looks like a long mail, but at the end of this post is my socket
wrapper attached.
I want to make a timeout procedure that starts counting down after the
socketbuffer is empty.
This connection is being used to transmit data following a RFC so I cann't
create a control protocol that tells me the data was received.
(And even if I could, I want the timeout procedure to start after I send all
data, because that makes for me the most sense. (say I am sending 128mb the
socket will take longer sending then the timeout interval))
Any questions/remarks, NOT related to my question, pls ask directly via
email, dont post on the news server because It toke me alot of effort to
create this post.

Sample case:
if u send 1 byte from a client in Canada to a server in Australia with a 28k
modem thats being shared by an office of 30 people connected to the slowest
profider. (etc.)
What I want to say is that 1 byte may take a couple of minutes, and I use 1
byte as an
example because I don't want to make a question more complicated.

TCP/IP is a async protocol, but due to the Berkley Connection engine it
keeps track of what was send and received and what was not, so when there is
a packet loss it will send again.
So a socket keeps the data sequential, and if we are optimistic, the only
thing that can go wrong is a socket error.

There are three stadiums(simplified):
(A) My object sends to the Winsock, (buffer is being fed, no data on the
network, no data on the remote point)
(B) Winsock processes his buffer and sends on the network and waits for a
confirment that the package is succesfull transmitted(buffer is 'empty',
data on the network, no data on the remote point)
(C) All data is correctly processed and transported (buffer is truely empty,
no data on the network,data on the remote point)

Relative to the Sample case:
I achieve (A) ofcourse, I would really want to know (C), but I would be
satisfied with (B). I know (B) can be achieved, I hope (C) is too.

VB.NET FrameWork 2003(all patched and updated):
I use the System.Net.Sockets to send/receive data (no
tcpclient/tcplistener), I made a receivethread in my wrapper, the
receivethread loops/sleeps while waiting for data and then fires a
datareceived event.
Within the waitingloop there is a timeout function but this doesn't work
properly (It will never timeout).
When I send by System.Net.Sockets.Socket.Send(buffer()) (<--this can be
10Mb) then it imitially returns to my thread, so the (internal) Send method
buffers it.
The System.Net.Sockets.Socket is a wrapper around the Win32 Socket 2 API's,
it makes internal calls to those api's, so I started reading if they forgot
implementing some functions, but they are all implemented.

I tried:
- The beginSend/EndSend (Async way with callback when command is finished)
This calls within the async object the Socket.Send method, so its no
help, I can better do Socket.Send myself.
- The Socket.Blocking Property, it only blocks the Receive method,
Socket.Send goes directly in the buffer and then it returns immitially.
- Socket.Poll Method, returns the accessrights of the socket, "may I use
this socket to write?"
-
getSocketOption(Socket/TCP/IP,SendBuffer/ReceiveBuffer/SendLowWater/ReceiveL
owWater/SendTimeout/ReceiveTimeout) Method
Throws an Exception

MyWrapper.vb:
Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.IO
Imports System.Collections
Imports System.Threading
Imports System.Diagnostics

Public Class SmartConnection
Public Event ConnectionOpened(ByVal pMe As SmartConnection)
Public Event DataReceived(ByVal pMe As SmartConnection, ByVal Data As
Message)
Public Event CouldntConnect(ByVal pMe As SmartConnection)
Public Event ConnectionClosed(ByVal pMe As SmartConnection)
Public Event [Error](ByVal pMe As SmartConnection, ByVal pErr As
Exception)
Public Event TimeOut(ByVal pme As SmartConnection)

Private _Socket As Socket
Private _ReadThread As Thread
Private _StopThread As Thread 'Lookup threadingpool
Private _Closing As Boolean = False
Private _InError As Boolean = False
Private _lport As Long
Private lasttimeout As Long
Private pHost As String
Private pPort As Long
Private pRead As Boolean
Private pTimeout As Long
Private _Iswriting As Boolean = False

Protected Overrides Sub Finalize()
_ReadThread = Nothing
_StopThread = Nothing
_Socket = Nothing
MyBase.Finalize()
End Sub

#Region " Properties"
Public ReadOnly Property IsClosing() As Boolean
Get
IsClosing = (_Closing Or _Socket Is Nothing)
End Get
End Property

Public ReadOnly Property Connected() As Boolean
Get
Try
Connected = ((Not IsClosing) AndAlso _Socket.Connected =
True)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Protected ReadOnly Property Receiving() As Boolean
Get
Try
If Not Connected Then Throw New Exception("Socket is not
connected")
Receiving = ((Not _ReadThread Is Nothing) AndAlso
_ReadThread.IsAlive)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Public ReadOnly Property IPlocal() As String
Get
Try
If Connected Then IPlocal = EP2IPS(_Socket.LocalEndPoint)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Public ReadOnly Property IPremote() As String
Get
Try
If Connected Then IPremote = EP2IPS(_Socket.RemoteEndPoint)
Catch e As Exception
OnError(e)
End Try
End Get
End Property
#End Region
#Region " Connect"
Public Overridable Sub ConnectTo(ByRef hostName As String, ByRef port As
Long, Optional ByVal timeout As Long = 0)
Try
StartConnect(hostName, port, timeout, True)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub ConnectToWithoutReading(ByRef hostName As String, ByRef
port As Long, Optional ByVal timeout As Long = 0)
Try
StartConnect(hostName, port, timeout, False)
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub StartConnect(ByRef hostName As String, ByRef port As Long,
ByRef timeout As Long, ByRef read As Boolean)
Try
If Not _ReadThread Is Nothing Then Throw New Exception("Already
trying to connect")
_ReadThread = New Thread(AddressOf ConnectThread)
pHost = hostName : pPort = port : pRead = read : pTimeout =
timeout
_ReadThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub ConnectThread()
Try
If pHost = "" Then Throw New ArgumentNullException("hostname")
If pPort < IPEndPoint.MinPort Or pPort > IPEndPoint.MaxPort Then
Throw New ArgumentOutOfRangeException("port", "ArgRange_Port")
_Socket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)
Try
_Socket.Blocking = True
_Socket.Connect(New
IPEndPoint(Dns.Resolve(pHost).AddressList(0), pPort))
_lport = CType(_Socket.LocalEndPoint, IPEndPoint).Port
If Not pRead Then
SetReadName("SC.Read[PreConnect]")
_ReadThread = Nothing
Else
SetReadName("SC.EarlyRead[" & _lport & "]")
End If
OnConnectionOpened()
If pRead Then Receive()
Catch e As SocketException 'e.ErrorCode = 10061
SetReadName("SC.Read[NoConnect]")
_ReadThread = Nothing
OnCouldntConnect()
Close()
End Try
Catch e As Exception
SetReadName("SC.Read[Error]")
_ReadThread = Nothing
OnError(e)
End Try
End Sub
#End Region
#Region " Receive"
Protected Sub StartReceive()
Try
If Receiving Then Throw New Exception("Receiving was already
started")
_ReadThread = New Thread(AddressOf Receive)
SetReadName("SC.LateRead[" & _lport & "]")
_ReadThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub Receive()
Dim i As Long
Dim b() As Byte
'Dim ds As String, dt As String
Try
Do While Connected
If pTimeout > 0 Then lasttimeout = CurrTick() + pTimeout
Do While _Socket.Available = 0
'dt = ds
'ds = "@" & _lport & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendBuffer) & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendLowWater) & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendTimeout)
'Debug.WriteLineIf(dt <> ds, ds)
_ReadThread.Sleep(ReceiveWait)
If IsClosing Then Exit Sub
If _Socket.Poll(0, SelectMode.SelectError) Then

'System.Runtime.InteropServices.Marshal.GetLastWin32Error())
'_Socket.GetSocketOption(SocketOptionLevel.IP,
SocketOptionName.Error)
OnError(New Exception("Socket Error"))
End If
If pTimeout > 0 Then
'If _Socket.Poll(0, SelectMode.SelectWrite) Then
'lasttimeout = CurrTick() + pTimeout
'Else
If lasttimeout <= CurrTick() Then
OnTimeOut()
Close()
Exit Sub
End If
'Endif
End If
Loop
ReDim b(_Socket.Available - 1)
'SyncLock _Socket
i = _Socket.Receive(b, SocketFlags.None)
'End SyncLock
If i < b.Length Then ReDim b(i - 1)
OnMessageReceived(New Message(b))
b = Nothing
Loop
Catch e As ThreadAbortException
Exit Sub
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region
#Region " Send"
Public Overridable Overloads Sub Send(ByRef data As String)
Try
Send(getbytes(data))
Catch e As Exception
OnError(e)
End Try
End Sub

Public Overridable Overloads Sub Send(ByRef data() As Byte)
Try
If Not Connected Then Throw New Exception("Socket isn't
connected")
_Iswriting = True
'SyncLock _Socket
_Socket.Send(data)
'End SyncLock
_Iswriting = False
Catch e As Exception
_Iswriting = False
OnError(e)
End Try
End Sub
#End Region
#Region " Close"
Public Overridable Sub Close() 'OR QUEE IT?
Try
If IsClosing Then Throw New Exception("Already is closing")
_Closing = True
_StopThread = New Thread(AddressOf DoClose)
_StopThread.Name = "SC.Stop[" & _lport & "]"
_StopThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub DoClose()
Try
_StopThread.Sleep(CloseWait)
Try
If Not _ReadThread Is Nothing Then
SetReadName("SC.Read[Close]")
If _ReadThread.IsAlive Then _ReadThread.Abort()
End If
Catch e As Exception
End Try
Try
If Not _Socket Is Nothing AndAlso _Socket.Connected Then
_Socket.Close()
Catch e As Exception
End Try
_ReadThread = Nothing
_Socket = Nothing
_Closing = False
_StopThread = Nothing
OnConnectionClosed()
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region
#Region " OnEvent"
Protected Overridable Sub OnError(ByRef pErr As Exception) 'If 2 errors
in diff threads?
Try
If Not _InError Then
_InError = True
Close()
_InError = False
End If
RaiseEvent Error(Me, pErr)
Catch e As Exception
Throw e
End Try
End Sub

Protected Sub OnTimeOut()
Try
RaiseEvent TimeOut(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnCouldntConnect()
Try
RaiseEvent CouldntConnect(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnConnectionClosed()
Try
RaiseEvent ConnectionClosed(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnConnectionOpened()
Try
RaiseEvent ConnectionOpened(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnMessageReceived(ByRef data As Message)
Try
RaiseEvent DataReceived(Me, data)
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region

Private Sub SetReadName(ByRef pName As String)
If Not _ReadThread Is Nothing AndAlso _ReadThread.Name Is Nothing
Then _ReadThread.Name = pName
End Sub

End Class
 
Actually Socket.Poll doesn't return the access rights, it tells you the
state of the socket. For example if you do a Send and then do a:

Socket.Poll(SelectMode.SelectRead)

It will return false until the server sends a response.

I think that's the closest you can get to what you want.

-Ron

Robert A. van Ginkel said:
Hello Fellow Developer,

This looks like a long mail, but at the end of this post is my socket
wrapper attached.
I want to make a timeout procedure that starts counting down after the
socketbuffer is empty.
This connection is being used to transmit data following a RFC so I cann't
create a control protocol that tells me the data was received.
(And even if I could, I want the timeout procedure to start after I send all
data, because that makes for me the most sense. (say I am sending 128mb the
socket will take longer sending then the timeout interval))
Any questions/remarks, NOT related to my question, pls ask directly via
email, dont post on the news server because It toke me alot of effort to
create this post.

Sample case:
if u send 1 byte from a client in Canada to a server in Australia with a 28k
modem thats being shared by an office of 30 people connected to the slowest
profider. (etc.)
What I want to say is that 1 byte may take a couple of minutes, and I use 1
byte as an
example because I don't want to make a question more complicated.

TCP/IP is a async protocol, but due to the Berkley Connection engine it
keeps track of what was send and received and what was not, so when there is
a packet loss it will send again.
So a socket keeps the data sequential, and if we are optimistic, the only
thing that can go wrong is a socket error.

There are three stadiums(simplified):
(A) My object sends to the Winsock, (buffer is being fed, no data on the
network, no data on the remote point)
(B) Winsock processes his buffer and sends on the network and waits for a
confirment that the package is succesfull transmitted(buffer is 'empty',
data on the network, no data on the remote point)
(C) All data is correctly processed and transported (buffer is truely empty,
no data on the network,data on the remote point)

Relative to the Sample case:
I achieve (A) ofcourse, I would really want to know (C), but I would be
satisfied with (B). I know (B) can be achieved, I hope (C) is too.

VB.NET FrameWork 2003(all patched and updated):
I use the System.Net.Sockets to send/receive data (no
tcpclient/tcplistener), I made a receivethread in my wrapper, the
receivethread loops/sleeps while waiting for data and then fires a
datareceived event.
Within the waitingloop there is a timeout function but this doesn't work
properly (It will never timeout).
When I send by System.Net.Sockets.Socket.Send(buffer()) (<--this can be
10Mb) then it imitially returns to my thread, so the (internal) Send method
buffers it.
The System.Net.Sockets.Socket is a wrapper around the Win32 Socket 2 API's,
it makes internal calls to those api's, so I started reading if they forgot
implementing some functions, but they are all implemented.

I tried:
- The beginSend/EndSend (Async way with callback when command is finished)
This calls within the async object the Socket.Send method, so its no
help, I can better do Socket.Send myself.
- The Socket.Blocking Property, it only blocks the Receive method,
Socket.Send goes directly in the buffer and then it returns immitially.
- Socket.Poll Method, returns the accessrights of the socket, "may I use
this socket to write?"
-
getSocketOption(Socket/TCP/IP,SendBuffer/ReceiveBuffer/SendLowWater/ReceiveL
owWater/SendTimeout/ReceiveTimeout) Method
Throws an Exception

MyWrapper.vb:
Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.IO
Imports System.Collections
Imports System.Threading
Imports System.Diagnostics

Public Class SmartConnection
Public Event ConnectionOpened(ByVal pMe As SmartConnection)
Public Event DataReceived(ByVal pMe As SmartConnection, ByVal Data As
Message)
Public Event CouldntConnect(ByVal pMe As SmartConnection)
Public Event ConnectionClosed(ByVal pMe As SmartConnection)
Public Event [Error](ByVal pMe As SmartConnection, ByVal pErr As
Exception)
Public Event TimeOut(ByVal pme As SmartConnection)

Private _Socket As Socket
Private _ReadThread As Thread
Private _StopThread As Thread 'Lookup threadingpool
Private _Closing As Boolean = False
Private _InError As Boolean = False
Private _lport As Long
Private lasttimeout As Long
Private pHost As String
Private pPort As Long
Private pRead As Boolean
Private pTimeout As Long
Private _Iswriting As Boolean = False

Protected Overrides Sub Finalize()
_ReadThread = Nothing
_StopThread = Nothing
_Socket = Nothing
MyBase.Finalize()
End Sub

#Region " Properties"
Public ReadOnly Property IsClosing() As Boolean
Get
IsClosing = (_Closing Or _Socket Is Nothing)
End Get
End Property

Public ReadOnly Property Connected() As Boolean
Get
Try
Connected = ((Not IsClosing) AndAlso _Socket.Connected =
True)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Protected ReadOnly Property Receiving() As Boolean
Get
Try
If Not Connected Then Throw New Exception("Socket is not
connected")
Receiving = ((Not _ReadThread Is Nothing) AndAlso
_ReadThread.IsAlive)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Public ReadOnly Property IPlocal() As String
Get
Try
If Connected Then IPlocal = EP2IPS(_Socket.LocalEndPoint)
Catch e As Exception
OnError(e)
End Try
End Get
End Property

Public ReadOnly Property IPremote() As String
Get
Try
If Connected Then IPremote = EP2IPS(_Socket.RemoteEndPoint)
Catch e As Exception
OnError(e)
End Try
End Get
End Property
#End Region
#Region " Connect"
Public Overridable Sub ConnectTo(ByRef hostName As String, ByRef port As
Long, Optional ByVal timeout As Long = 0)
Try
StartConnect(hostName, port, timeout, True)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub ConnectToWithoutReading(ByRef hostName As String, ByRef
port As Long, Optional ByVal timeout As Long = 0)
Try
StartConnect(hostName, port, timeout, False)
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub StartConnect(ByRef hostName As String, ByRef port As Long,
ByRef timeout As Long, ByRef read As Boolean)
Try
If Not _ReadThread Is Nothing Then Throw New Exception("Already
trying to connect")
_ReadThread = New Thread(AddressOf ConnectThread)
pHost = hostName : pPort = port : pRead = read : pTimeout =
timeout
_ReadThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub ConnectThread()
Try
If pHost = "" Then Throw New ArgumentNullException("hostname")
If pPort < IPEndPoint.MinPort Or pPort > IPEndPoint.MaxPort Then
Throw New ArgumentOutOfRangeException("port", "ArgRange_Port")
_Socket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)
Try
_Socket.Blocking = True
_Socket.Connect(New
IPEndPoint(Dns.Resolve(pHost).AddressList(0), pPort))
_lport = CType(_Socket.LocalEndPoint, IPEndPoint).Port
If Not pRead Then
SetReadName("SC.Read[PreConnect]")
_ReadThread = Nothing
Else
SetReadName("SC.EarlyRead[" & _lport & "]")
End If
OnConnectionOpened()
If pRead Then Receive()
Catch e As SocketException 'e.ErrorCode = 10061
SetReadName("SC.Read[NoConnect]")
_ReadThread = Nothing
OnCouldntConnect()
Close()
End Try
Catch e As Exception
SetReadName("SC.Read[Error]")
_ReadThread = Nothing
OnError(e)
End Try
End Sub
#End Region
#Region " Receive"
Protected Sub StartReceive()
Try
If Receiving Then Throw New Exception("Receiving was already
started")
_ReadThread = New Thread(AddressOf Receive)
SetReadName("SC.LateRead[" & _lport & "]")
_ReadThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub Receive()
Dim i As Long
Dim b() As Byte
'Dim ds As String, dt As String
Try
Do While Connected
If pTimeout > 0 Then lasttimeout = CurrTick() + pTimeout
Do While _Socket.Available = 0
'dt = ds
'ds = "@" & _lport & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendBuffer) & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendLowWater) & ","
'ds += _Socket.GetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.SendTimeout)
'Debug.WriteLineIf(dt <> ds, ds)
_ReadThread.Sleep(ReceiveWait)
If IsClosing Then Exit Sub
If _Socket.Poll(0, SelectMode.SelectError) Then

'System.Runtime.InteropServices.Marshal.GetLastWin32Error())
'_Socket.GetSocketOption(SocketOptionLevel.IP,
SocketOptionName.Error)
OnError(New Exception("Socket Error"))
End If
If pTimeout > 0 Then
'If _Socket.Poll(0, SelectMode.SelectWrite) Then
'lasttimeout = CurrTick() + pTimeout
'Else
If lasttimeout <= CurrTick() Then
OnTimeOut()
Close()
Exit Sub
End If
'Endif
End If
Loop
ReDim b(_Socket.Available - 1)
'SyncLock _Socket
i = _Socket.Receive(b, SocketFlags.None)
'End SyncLock
If i < b.Length Then ReDim b(i - 1)
OnMessageReceived(New Message(b))
b = Nothing
Loop
Catch e As ThreadAbortException
Exit Sub
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region
#Region " Send"
Public Overridable Overloads Sub Send(ByRef data As String)
Try
Send(getbytes(data))
Catch e As Exception
OnError(e)
End Try
End Sub

Public Overridable Overloads Sub Send(ByRef data() As Byte)
Try
If Not Connected Then Throw New Exception("Socket isn't
connected")
_Iswriting = True
'SyncLock _Socket
_Socket.Send(data)
'End SyncLock
_Iswriting = False
Catch e As Exception
_Iswriting = False
OnError(e)
End Try
End Sub
#End Region
#Region " Close"
Public Overridable Sub Close() 'OR QUEE IT?
Try
If IsClosing Then Throw New Exception("Already is closing")
_Closing = True
_StopThread = New Thread(AddressOf DoClose)
_StopThread.Name = "SC.Stop[" & _lport & "]"
_StopThread.Start()
Catch e As Exception
OnError(e)
End Try
End Sub

Private Sub DoClose()
Try
_StopThread.Sleep(CloseWait)
Try
If Not _ReadThread Is Nothing Then
SetReadName("SC.Read[Close]")
If _ReadThread.IsAlive Then _ReadThread.Abort()
End If
Catch e As Exception
End Try
Try
If Not _Socket Is Nothing AndAlso _Socket.Connected Then
_Socket.Close()
Catch e As Exception
End Try
_ReadThread = Nothing
_Socket = Nothing
_Closing = False
_StopThread = Nothing
OnConnectionClosed()
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region
#Region " OnEvent"
Protected Overridable Sub OnError(ByRef pErr As Exception) 'If 2 errors
in diff threads?
Try
If Not _InError Then
_InError = True
Close()
_InError = False
End If
RaiseEvent Error(Me, pErr)
Catch e As Exception
Throw e
End Try
End Sub

Protected Sub OnTimeOut()
Try
RaiseEvent TimeOut(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnCouldntConnect()
Try
RaiseEvent CouldntConnect(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnConnectionClosed()
Try
RaiseEvent ConnectionClosed(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnConnectionOpened()
Try
RaiseEvent ConnectionOpened(Me)
Catch e As Exception
OnError(e)
End Try
End Sub

Protected Sub OnMessageReceived(ByRef data As Message)
Try
RaiseEvent DataReceived(Me, data)
Catch e As Exception
OnError(e)
End Try
End Sub
#End Region

Private Sub SetReadName(ByRef pName As String)
If Not _ReadThread Is Nothing AndAlso _ReadThread.Name Is Nothing
Then _ReadThread.Name = pName
End Sub

End Class
Click to expand...
 
.....
From this high level descriptions of the problem, I would create a
Application level Msg/Ack handshake to truely make
sure the remote is responding to my local requests.

I don't think peeking into the TCP stack at one system can give
your enough info to confirm the data get to the remote.
 
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