CODEWITHSUNDEEP
javaandroidsocketstcptcpclient
vij
vij

Reputation: 143

How to overcome the hanging of TCP client when TCP server is not running?

I am trying to establish a TCP socket connection between my Android phone and PC for file transfer. A TCP Server program will in PC and TCP client program run in Android. When the server program is running everything works fine. But when the server program is not running and when the client tries to establish the connection, the client hangs(in the sense it waits for long time till it establish theconnection ). How to overcome this problem? I want to terminate the socket as soon the client finds that no such server is running. Is it possible to do that?

Upvotes: 1

Views: 2213

Answers (3)

user207421
user207421

Reputation: 310980

You can control the connect timeout of a Socket by constructing a new Socket() and using the Socket.connect(SocketAddress, timeout) method.

Note that you can use this to decrease the default timeout, which is a bit over a minute, but not to increase it.

Upvotes: 3

LiMar
LiMar

Reputation: 2972

The problem seems to be in the server configuration (PC in your case). It might have prohibited the outgoing ICMP traffic, which is responsible of notifying the clients about closed ports.

Try to telnet your service port when it's not running. Like

telnet <my.pc.address> <my-port>

On "normal" configurations it should immediately fail (exactly as your client app shoud) with 

telnet: Unable to connect to remote host: Connection refused

On tricky configurations with firewalls, ICMP prohibited, etc it will "hang" for a long time, "thinking" that the service is running and waiting for it's answer.

Upvotes: 2

pvlissidis
pvlissidis

Reputation: 184

I believe you need to play with the timeout settings of the Socket API. See here for some more detailed discussion:

Set timeout for socket

Upvotes: 3

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