.net - tcpClient.State analogue in vb.net (versus vb6.0) -

i used next code in vb6.0 winsock object tcpclient:

dim sconst(10) string dim st integer  sconst(0) = "closed" sconst(1) = "open" sconst(2) = "listening" sconst(3) = "connectionpending" sconst(4) = "resolvinghost" sconst(5) = "hostresolved" sconst(6) = "connecting" sconst(7) = "connected" sconst(8) = "closing" sconst(9) = "error" st = tcpclient.state textbox1.text = sconst(st)  

now im using vb.net , want same. there no .state method tcpclient objects! there cpclient.connected returns boolean yes or not. how can alike vb6.0?

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using visual vinsent's answer made this:

public class form1     dim status1 string     dim status2 string  private sub btn_connect5001_click(sender object, e eventargs)_                    handles btn_connect5001.click         ' create tcpclient , connect         tcpclnt2 = new tcpclient              try             tcpclnt2.connect("192.168.1.177", 5001)         catch         end try     end sub      private sub btn_disconnect5001_click(sender object, e eventargs)_                      handles btn_disconnect5001.click         ' close tcpclient         tcpclnt2.close()     end sub  private sub timer1_tick(sender object, e eventargs) handles timer1.tick         ' check status every 300ms         status2= new ipendpoint(ipaddress.parse("192.168.1.177"),5001).getstatus().tostring()          textbox1.text = dns.gethostname + environment.newline +              "port 1  " + status2 + environment.newline     end sub end class 

the problem is: @ start status2 "unknown", if connect first time status2 "established". if disconnect became "timewait". if connect 1 more time stay "timewait". never change value then.

neither tcpclient nor underlying socket appears have such implementation, wrote 3 extension methods you.

what they iterate every active tcp connection on computer using ipglobalproperties class , getactivetcpconnections() method, match connection against tcpclient's local , remote ip-address.

extensions.vb

imports system.runtime.compilerservices imports system.reflection imports system.net imports system.net.sockets imports system.net.networkinformation  public module extensions     ''' <summary>     ''' dynamically gets object's property name.     ''' </summary>     ''' <param name="obj">the object which's property get.</param>     ''' <param name="propertyname">the name of property get.</param>     <extension()> _     public function getproperty(byval obj object, byval propertyname string) object         return obj.gettype().invokemember(propertyname, _                                            bindingflags.getproperty _                                             or bindingflags.ignorecase _                                              or bindingflags.public _                                               or bindingflags.nonpublic _                                                or bindingflags.instance _                                                 or bindingflags.static, _                                            nothing, obj, nothing)     end function      ''' <summary>     ''' gets status of tcp connection.     ''' </summary>     ''' <param name="client">the tcpclient which's status get.</param>     ''' <remarks></remarks>     <extension()> _     public function getstatus(byval client tcpclient) tcpstate         if client nothing orelse client.client nothing return tcpstate.unknown         each tcpconnection tcpconnectioninformation in ipglobalproperties.getipglobalproperties().getactivetcpconnections()              if tcpconnection.localendpoint.equals(client.client.localendpoint) andalso _                  tcpconnection.remoteendpoint.equals(client.client.remoteendpoint)                 return tcpconnection.state             end if          next         return tcpstate.unknown     end function      ''' <summary>     ''' gets status of tcp connection.     ''' </summary>     ''' <param name="endpoint">the ipendpoint (ip-address) of tcp connection which's status get.</param>     ''' <remarks></remarks>     <extension()> _     public function getstatus(byval endpoint ipendpoint) tcpstate         if endpoint nothing return tcpstate.unknown         each tcpconnection tcpconnectioninformation in ipglobalproperties.getipglobalproperties().getactivetcpconnections()              if tcpconnection.localendpoint.equals(endpoint) orelse _                  tcpconnection.remoteendpoint.equals(endpoint)                 return tcpconnection.state             end if          next         return tcpstate.unknown     end function      ''' <summary>     ''' gets status of tcp listener.     ''' </summary>     ''' <param name="listener">the tcplistener which's status get.</param>     ''' <remarks></remarks>     <extension()> _     public function getstatus(byval listener tcplistener) tcpstate         if listener nothing orelse listener.server nothing return tcpstate.unknown          'per source code, active listeners in "listen" state:         'https://referencesource.microsoft.com/#system/net/system/net/networkinformation/systemipglobalproperties.cs,51fa569e558be704         if listener.getproperty("active") = true return tcpstate.listen          return directcast(listener.localendpoint, ipendpoint).getstatus() 'the listener not in active state.     end function end module 

now status of connection have 3 options:

1. getting status of tcpclient:

   dim status string = yourclient.getstatus().tostring() 

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2. getting status of tcplistener:

   dim status string = yourlistener.getstatus().tostring() 

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3. getting status of connection specified ip-address:

   dim status string = new ipendpoint(ipaddress.parse("your ip-address here"), yourporthere).getstatus().tostring() 

important notes:

• the tostring() call necessary if want status's name (for example established), otherwise you'll enumeration value normal integer (for example 3).

• getting status of tcpclient or tcplistener work if neither nor underlying sockets disposed. if wish status of disconnected tcpclient/-listener have use option no. 3 , exact ip-address , port.

  • disconnected tcp connections can interesting because still exist after being closed , have state little while. examples of disconnected states closewait or timewait.

read more:

• ipglobalproperties class - msdn

• ipglobalproperties.getactivetcpconnections() method - msdn

• system.net.networkinformation namespace - msdn

• tcp protocol operation - wikipedia (a list of different tcp connection states)

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edit:

to fix problem connections lingering in close_wait or time_wait state can set underlying socket linger 0 seconds , dispose it. doing cause socket perform so-called "hard close" sending rst (reset) packet instead of fin (fin tells socket connection closed , should go close-/time_wait). method forces connection close , no late/retransmitted packets mapped application after that.

it's mentioned on msdn documentation:

if l_onoff member of linger structure nonzero , l_linger member zero, closesocket not blocked if queued data has not yet been sent or acknowledged. called hard or abortive close, because socket's virtual circuit reset immediately, , unsent data lost. on windows, recv call on remote side of circuit fail wsaeconnreset.

this can done in simple extension method (put in extensions module):

''' <summary> ''' forces specified tcpclient close without sending fin other endpoint. stop connection going time_wait, close_wait or fin_* state. ''' </summary> ''' <param name="client">the tcpclient close.</param> ''' <remarks></remarks> <extension()> _ public sub forceclose(byval client tcpclient)     client.client.lingerstate = new lingeroption(true, 0) 'set socket linger, 0 seconds (causes current connection send rst-packet , terminate).     client.client.dispose() 'dispose underlying socket instead of graceful shutdown.     client.close() 'close tcpclient. end sub 

then call this:

yourclient.forceclose()