# Problems using gets() on a socket

**URL:** <https://www.ruby-forum.com/t/problems-using-gets-on-a-socket/194044>\
**Category:** Ruby\
**Created:** [August 28, 2010, 11:24pm UTC](https://www.ruby-forum.com/t/problems-using-gets-on-a-socket/194044 "2010-08-28T23:24:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![geometic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/bbce88/32.png) [@geometic](https://www.ruby-forum.com/u/geometic)\
**Post date:** [August 28, 2010, 11:24pm UTC](https://www.ruby-forum.com/t/problems-using-gets-on-a-socket/194044/1 "2010-08-28T23:24:10Z")

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Hi,

I have built a telnet “chat server” using TCPserver and a select  
statement.

If a client exits “cleanly” (such as by closing the shell in which  
telnet is running), I can recognize the socket as being terminated using  
sock.eof? and everything’s fine.

But if a client does wacky stuff like suspend their telnet process with  
ctrl+z, then my server hangs at this line:

s = sock.gets()

(where s is a string and sock is the socket of the client)

I tried using s = sock.read and the server could not get past that line,  
even for successfully connected clients. I tried using s =  
sock.recvfrom(500)[0] but when the client hits that line I get the error  
“in `recvfrom’: recv for buffered IO (IOError)”.

Any help you can provide would be gratefully received!

Very best,

- Andrew

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<div class="post-metadata">

**Author:** ![geometic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/bbce88/32.png) [@geometic](https://www.ruby-forum.com/u/geometic)\
**Post date:** [August 29, 2010, 11:40am UTC](https://www.ruby-forum.com/t/problems-using-gets-on-a-socket/194044/2 "2010-08-29T11:40:27Z")

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On 28.08.2010 23:24, Geometric Patterns wrote:

> s = sock.gets()
> 
> (where s is a string and sock is the socket of the client)

Well, that’s perfectly OK since from the socket connection’s point of  
view nothing changed. The process is still there and both ends can  
still exchange data (after the client has been woken up which can happen  
at any point in time).

> I tried using s = sock.read and the server could not get past that line,  
> even for successfully connected clients. I tried using s =  
> sock.recvfrom(500)[0] but when the client hits that line I get the error  
> “in `recvfrom’: recv for buffered IO (IOError)”.
> 
> Any help you can provide would be gratefully received!

If you want to deal with those situations you probably need to extend  
your protocol to be able to intermediately park a chat session and  
resume it later. You could even release the socket in between to not  
waste too many resources. This also requires that your client process  
catches the signal, notifies the server from the session park and  
release the socket. (Note, I am not 100% sure that you can do this and  
still put the process to sleep.)

You can as well simply do nothing because only these things can happen:

1. somebody wakes up the client process and communication resumes  
normally.

2. somebody kills the client in which case the socket is released and  
the server will eventually throw an exception or return nil from #gets.

3. network is disconnected or some other error in which case the server  
likely gets an exception.

Kind regards

robert

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<div class="post-metadata">

**Author:** ![geometic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/bbce88/32.png) [@geometic](https://www.ruby-forum.com/u/geometic)\
**Post date:** [August 30, 2010, 7:38pm UTC](https://www.ruby-forum.com/t/problems-using-gets-on-a-socket/194044/3 "2010-08-30T19:38:49Z")

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> But if a client does wacky stuff like suspend their telnet process with  
> ctrl+z, then my server hangs at this line:
> 
> s = sock.gets()

This socket tutorial might help you:  
[http://en.wikibooks.org/wiki/Ruby\_Programming/Reference/Objects/Socket](http://en.wikibooks.org/wiki/Ruby_Programming/Reference/Objects/Socket)