multithreading - C# Socket.receive continuously receives 0 bytes and does not block in the loop -

i trying write simplest multithreaded tcp server in c#, receives data multiple clients.

every time new client connected, socket connection established , socket passed argument new class function, after while loop runs , receives data till client connected.

the problem here "socket.receive" not blocking , receives 0 bytes of data. loop runs continuously, without blocking @ socket.receive ("clientsocket.receive(bb)" in code.).

i using chrome browser client testing. if use other client, behavior of tcp server remains same.

the client sends data once server continuously receives 0 bytes , while loop keeps on running.

i pasting server output reference.

please in blocking server @ socket.receive wait next client transmission. strange thing if 0 bytes received, exception not called.

please help.

using system; using system.collections.generic; using system.linq; using system.text; using system.net; using system.net.sockets; using system.threading; threading; using system.timers; using system.security; using system.security.permissions; namespace server {     static class constants     {         public const int port = 8080;         public const int buffer_size = 512;       }     class program     {         static public string localipaddress()         {             iphostentry host;             string localip = "";             host = dns.gethostentry(dns.gethostname());             foreach (ipaddress ip in host.addresslist)             {                 if (ip.addressfamily == addressfamily.internetwork)                 {                     localip = ip.tostring();                     break;                 }             }             return localip;             //return ip;         }          static void main(string[] args)         {             //ipendpoint ipobj = new ipendpoint(ipaddress.parse("server ip goes here"), 20487); //20487 port. can change according wish             system.net.ipaddress ip = ipaddress.any;             int port = constants.port;             tcplistener listnerobj = new tcplistener(ip, port);             listnerobj.start();             string client_addr;             string[] client_addr_split;             string ip_string = localipaddress();              console.writeline("server started on {0}:{1}", ip_string, port);             while (true)             {                 console.writeline("================================");                 console.writeline("**    waiting client     **");                 socket clientsocket = listnerobj.acceptsocket(); // waiting client connect                  client_addr = clientsocket.remoteendpoint.tostring();                 client_addr_split = client_addr.split(':');                 client_addr = client_addr_split[0];                  console.writeline("client connected {0}", client_addr);                 parameterizedthreadstart thread = delegate { new communication().docommunicate(clientsocket, client_addr); };                 thread th = new thread(thread);                 th.start(); // start thread here              }         }          class communication         {             public int bytereceived;             public byte[] bb;             public void docommunicate(socket clientsocket, string client_addr)             {                 clientsocket.blocking = true;                 bb = new byte[constants.buffer_size];                  //console.writeline("***** entered docommunicate *****");                 while (clientsocket.connected)                 {                     //console.writeline("entered while");                     try                     {                         //console.writeline("entered try");                         console.writeline("waiting recieve data ip : client_addr");                         //int receiveddatalength = client.receive(receivedbytes, 0, receivedbytes.length, socketflags.none);                         bytereceived = clientsocket.receive(bb, 0, bb.length, socketflags.none);                         //bytereceived = clientsocket.receive(bb);                     }                     catch (socketexception e)                     {                         console.writeline("error: socket exception.\n{0}\n{1}.", e.message, e.errorcode);                         break;                     }                     catch (argumentnullexception e)                     {                         console.writeline("error : argument null exception.\n{0}", e.message);                         break;                     }                     catch (objectdisposedexception e)                     {                         console.writeline("error : socket disposed exception caught.\n{0}", e.message);                         break;                     }                     catch (securityexception e)                     {                         console.writeline("error: security exception.\n{0}", e.message);                         break;                     }                     //clientsocketglobal.send(encoding.default.getbytes("hello client"), socketflags.none);                     console.writelinewriteline("received byte count : {0}, ip : {1}", bytereceived, client_addr); // whatever want data recieved. parsing , storing etc.                     console.writeline(encoding.utf8.getstring(bb));                 }                 //console.writeline("while loop exited");                 console.writeline("socked , class object  disposed");                 clientsocket.close();                 clientsocket.dispose();                 gc.collect();             }         }     } } 

output of server :

server started on 10.0.0.2:8080 ================================ **    waiting client     ** client connected 10.0.0.2 ================================ **    waiting client     ** client connected 10.0.0.2 ================================ **    waiting client     ** waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 386, ip : 10.0.0.2 /helloworld http/1.1 host: 10.0.0.2:8080 connection: keep-alive cache-control: max-age=0 accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 user-agent: mozilla/5.0 (windows nt 6.0; wow64) applewebkit/537.36 (khtml, gecko) chrome/30.0.1599.69 safari/537.36 accept-encoding: gzip,deflate,sdch accept-language: en-gb,en-us;q=0.8,en;q=0.6   waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 waiting recieve data ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 received byte count : 0, ip : 10.0.0.2 

if received 0 bytes, means sender has closed send socket. in socket, send , receive channels separate; expect happening send (their receive) still open , available, hence clientsocket.connected returning true (you can still send them reply), but: closed send (your receive) sent payload (this common, indicate end of batch). basically, need detect 0-byte receive, , treat end: no more data ever incoming once have had non-positive reply receive. write response need write (they can still listening, though never speak again), , shutdown socket.

as side note: in http/1.1 connection: keep-alive, can keep socket open ready send next request - looks in case, didn't. closed socket after issuing request. fine. serve response , close socket completely. no more requests incoming.