[Gambas-user] [SOLVED] Socket Horror!

[nospam.nospam.nospam at ...626...]

Some of you will know that I've had truckloads of socket horror with a proxy 
server I've written in gambas. Well I had more socket horror just now. 
Everything was working fine last night but not when I booted up this 
afternoon.

The server socket starts and listens.
The server socket detects an incoming client connection.
The server socket is established and ready.
A connection to a remote server is established.

After some time, the client gets no response so the client closes the
connection.

The client reconnects.
The server socket starts and listens...

And round and round it went.

Socket_Read() never fired, and I know nothing changed because I was using 
the proxy for several hours in runtime mode and it was running flawlessly, 
then I went to bed without ever touching the source code.

It turns out that the remote server IP address had changed. It now makes 
sense that Socket_Read() never fired because the client application must 
wait for the server to respond, which is the correct behaviour specified by 
a certain RFC, but since the server was no longer on the same IP address 
there was no response; the server wasn't there, it was on some other IP 
address.

I checked the server and it was on a very short lease, which explains why it 
appeared to work and not work at no particular time. At one point everything 
started working when I set a single property in the client socket. I now 
believe that the two events (me setting the property, and the proxy starting 
to work) were independent and mere coincidence was what caused it to work, 
i.e. the server acquired a new lease and, it just so happens, it got the 
same IP address that we expected it to have.

I have now given the server a permanent IP.

So there you have it. You now know how it is that a remote server not being 
on the IP address that you expect it to be on can cause the client 
Socket_Read() to never fire.

Thanks to all those who offered commonsense suggestions. I could have sorted 
this problem much quicker if I had bothered to check the Status property of 
the socket that connects to the remote server. But hey, it's not even in 
alpha stage yet :)