Re: [ ruby-Bugs-2047 ] TCPSocket fails to bind first time on certain FreeBSD configs

On 20 Jun 2005, at 04:29, [e-mail] wrote:

> Bugs item #2047, was opened at 2005-06-20 12:24
> You can respond by visiting:
> http://rubyforge.org/tracker/? 
> func=detail&atid=1698&aid=2047&group_id=426
>
> Category: Standard Library
> Group: None
> Status: Open
> Resolution: None
> Priority: 3
> Submitted By: Brian Candler (bcandler)
> Assigned to: Nobody (None)
> Summary: TCPSocket fails to bind first time on certain FreeBSD configs
>
> Initial Comment:
> I have some very strange reproducible behaviour with TCPSocket. It  
> differs
> between two machines which are almost identical: one is FreeBSD-5.4- 
> RELEASE,
> the other is FreeBSD-5.4-STABLE dating from only a week or so after
> 5.4-RELEASE. Both report Ruby version as
> "ruby 1.8.2 (2004-12-25) [i386-freebsd5]"
>
> The 5.4-RELEASE machine is running a GENERIC kernel with IPv6  
> enabled. The
> 5.4-STABLE machine has a slightly customised kernel, with IPv6  
> turned off.
> This is the only thing which I can imagine is significant.
>
> Now, it's the 5.4-STABLE machine (no IPv6) which is being strange:
>
> $ irb
> irb(main):001:0> require 'socket'
> => true
> irb(main):002:0> a = TCPServer.new(1234)
> => #<TCPServer:0x813aed0>
> irb(main):003:0>
>
> At this point, you'd expect the server to be listening on port 1234.
> However, it isn't: in another window I can try

No, it is.  Remove -4 from sockstat args...

> $ telnet localhost 1234
> Trying 127.0.0.1...
> telnet: connect to address 127.0.0.1: Connection refused
> telnet: Unable to connect to remote host
> $ sockstat -4l
> USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN  
> ADDRESS
> mailnull exim-4.50- 432   4  tcp4   *:25                  *:*
> root     sshd       393   4  tcp4   *:22                  *:*
> root     lpd        363   7  tcp4   *:515                 *:*
> root     syslogd    266   6  udp4   *:514                 *:*

$ sockstat -l | grep 1234
eric     ruby18     28234 3  tcp6   *:1234                *:*
$ telnet localhost 1234
Trying ::1...
Connected to localhost.coop.robotcoop.com.
Escape character is '^]'.
^]
telnet> quit
Connection closed.

> However, as soon as I create a *second* TCPServer object, it works.
>
> This is completely repeatable. Now: if I give an IP address  
> explicitly to
> bind to, it's OK:

[snip]

Now it is listening on *two* ports:

$ sockstat -l | grep 1234
eric     ruby18     28325 3  tcp4   *:1234                *:*
eric     ruby18     28234 3  tcp6   *:1234                *:*

> So I have a workaround which solves my problem - but it looks like  
> there's something strange going on under the surface.

You need to bind both IPv6 and IPv4 addresses on IPv6-enabled hosts.   
The following should work on both IPv4-only and IPv4/IPv6 hosts (I  
took it from WEBrick):

$ cat x.rb
require 'socket'
res = Socket.getaddrinfo(nil, 1234, Socket::AF_UNSPEC,  
Socket::SOCK_STREAM, 0,
                          Socket::AI_PASSIVE)

sockets = []

res.each do |ai|
   sockets << TCPServer.new(ai[3], ai[1])
end

sleep 10

$ ruby x.rb &
[2] 28585
$ sockstat -l | grep 1234
eric     ruby       28585 3  tcp6   *:1234                *:*
eric     ruby       28585 4  tcp4   *:1234                *:*

Also, what is in your /etc/hosts?

$ cat /etc/hosts
::1                     localhost.coop.robotcoop.com localhost
127.0.0.1               localhost.coop.robotcoop.com localhost

-- 
Eric Hodel - [e-mail] - http://segment7.net
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