Re: [PATCH] SlavePool: fix unresolvable hostname exception

[Ondrej Lichtner]

On Mon, Jul 31, 2017 at 03:51:10PM +0200, Jan Tluka wrote:
>  If LNST controller processes a pool that contains a machine with a
> hostname
>  that can't be resolved by DNS the controller fails with unhandled exception.
>  The exception is raised on shutdown of the socket used to connect to the
>  machine. Since the connection on the socket did not succeed the attempt to
>  shutdown the connection is an error. Unfortunately this error is not detected
>  by checking SO_ERR in getsockopt() after calling select() on the socket.
>  
>  The fix is to mark the machine unavailable immediately unless the error code
>  raised by connect call is EINPROGRESS meaning the connection proceeded to
>  establishing phase (the hostname was succesfully resolved).
>  
>  Fixes: 5498ba2 ("SlavePool: properly close sockets after connection check")
>  Fixes issue #188
>  
>  Signed-off-by: Jan Tluka <jtluka(a)redhat.com&gt;
>  ---
>   lnst/Controller/SlavePool.py | 18 ++++++++++++++++--
>   1 file changed, 16 insertions(+), 2 deletions(-)
>  
>  diff --git a/lnst/Controller/SlavePool.py b/lnst/Controller/SlavePool.py
>  index 5f94b07..5069f50 100644
>  --- a/lnst/Controller/SlavePool.py
>  +++ b/lnst/Controller/SlavePool.py
>  @@ -15,6 +15,7 @@ rpazdera(a)redhat.com (Radek Pazdera)
>   
>   import logging
>   import os
>  +import errno
>   import re
>   import socket
>   import select
>  @@ -104,8 +105,21 @@ class SlavePool:
>                   s.settimeout(0)
>                   try:
>                       s.connect((hostname, port))
>  -                except:
>  -                    pass
>  +                except socket.error as msg:
>  +                    # if the error is other than EINPROGRESS, e.g. the stack
>  +                    # could not resolve name, the machine should become unavailable
>  +                    try:
>  +                        en = msg.errno
>  +                    except AttributeError:
>  +                        en = 0
>  +
>  +                    if en != errno.EINPROGRESS:
>  +                        pool[m_id]["available"] = False
>  +                        s.close()
>  +                        logging.debug("Bypassing machine '%s' (%s)" %
>  +                            (m_id, msg))
>  +                        continue
>  +
>                   check_sockets[s] = m_id
>   
>               while len(check_sockets) > 0:
>  -- 
>  2.7.5
>  _______________________________________________
>  LNST-developers mailing list -- lnst-developers(a)lists.fedorahosted.org
>  To unsubscribe send an email to lnst-developers-leave(a)lists.fedorahosted.org 
pushed, thanks.

-Ondrej