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Ruby socket does not get reply

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  Ruby socket does not get reply Robert Garrido <rob_gar_esp@hotmail.com> - 2011-05-13 12:19 -0500
    Re: Ruby socket does not get reply 7stud -- <bbxx789_05ss@yahoo.com> - 2011-05-13 13:08 -0500
    Re: Ruby socket does not get reply Roger Pack <rogerpack2005@gmail.com> - 2011-05-13 13:53 -0500
      Re: Ruby socket does not get reply 7stud -- <bbxx789_05ss@yahoo.com> - 2011-05-13 14:03 -0500
        Re: Ruby socket does not get reply Robert Garrido <rob_gar_esp@hotmail.com> - 2011-05-14 02:41 -0500
          Re: Ruby socket does not get reply 7stud -- <bbxx789_05ss@yahoo.com> - 2011-05-14 12:16 -0500
            Re: Ruby socket does not get reply 7stud -- <bbxx789_05ss@yahoo.com> - 2011-05-14 12:42 -0500
            Re: Ruby socket does not get reply Gary Wright <gwtmp01@mac.com> - 2011-05-15 19:10 -0500

#4501 — Ruby socket does not get reply

Hi all,

I use a TCP connection and send some data like this:

  begin
    session = "mysession"
    socket = TCPSocket.new(tcpaddress, port)
    socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
    puts "sending to socket HELO " + session
    socket.write ('HELO ' + session)
    puts socket.read
    socket.close
  rescue Exception => myException
    puts "Exception rescued : #{myException}"
  end

The socket never gets a reply, however telnet does:

$ telnet some_ip port
Trying some_ip...
Connected to some_ip
Escape character is '^]'.
HELO mysession
OK


As you can see the remote server replies "OK" as expected. What's wrong?

Thanks in advanced!

PS: I have used puts and send methods also

-- 
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#4507

Robert Garrido wrote in post #998563:

>
>
> As you can see the remote server replies "OK" as expected. What's wrong?
>

If the server is expecting 'line oriented input', then the server will
continue trying to read from the socket until it encounters a newline,
i.e. you need to end the data you send with a newline.

-- 
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#4514

>     puts socket.read

This call (read) blocks until the other end of the connection closes it.
-r

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#4515

Roger Pack wrote in post #998583:
>>     puts socket.read
>
> This call (read) blocks until the other end of the connection closes it

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#4533

This is the fix:

socket.write("HELO " + session + "\r\n")

Thanks :D

-- 
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#4541

Robert Garrido wrote in post #998661:
> This is the fix:
>
> socket.write("HELO " + session + "\r\n")
>
> Thanks :D

Just be aware that ruby is going to convert a "\n" to "\r\n" on windows, 
so on windows you will actually be wrting:

"\r\n"
= "\r" + "\n"
= "\r" + "\r\n"
= "\r\r\n"

That may or may not make a difference to a particular program.

-- 
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#4542

7stud -- wrote in post #998709:
> That may or may not make a difference to a particular program.
>

One way to avoid the newline conversion is to use the actualy ascii code 
for a newline instead of "\n":


"\r\n" in octal:

"\015\012"

"\r\n" in hex:

"x0D\x0A"

To avoid the ugliness of those escape sequences, perl has the constant 
CRLF, which can be used in strings, when correct reading of the data 
requires that line endings be marked by exactly one "\r" and one "\n". 
However, I don't think ruby copied that feature from perl.

-- 
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#4580

On May 14, 2011, at 1:16 PM, 7stud -- wrote:
> Just be aware that ruby is going to convert a "\n" to "\r\n" on windows, 
> so on windows you will actually be wrting:
> 
> "\r\n"
> = "\r" + "\n"
> = "\r" + "\r\n"
> = "\r\r\n"
> 
> That may or may not make a difference to a particular program.

I don't have a Windows system to test on but I'm pretty sure that sockets are always automatically opened in binary mode.  On my Mac OS system:

irb> socket = TCPSocket.new("www.google.com", 80)
 => #<TCPSocket:fd 4> 
irb  > socket.binmode?
 => true 

The HTTP protocol requires "\r\n" line endings though so they have to be written explicitly on the binary socket as described in the earlier messages.

Gary Wright

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