Bug 343

Summary: Only try connect to first address when creating tunnel
Product: Portable OpenSSH Reporter: Stig Venaas <stig>
Component: sshdAssignee: Damien Miller <djm>
Status: CLOSED FIXED    
Severity: normal    
Priority: P2    
Version: -current   
Hardware: All   
OS: All   
Bug Depends on:    
Bug Blocks: 1452    
Attachments:
Description Flags
try subsequent addresses none

Description Stig Venaas 2002-07-09 04:08:21 AEST 
In connect_to() in channels.c there is a loop trying to connect to each
address returned by getaddrinfo() until connect() is successful or
EINPROGRESS is returned. The socket is non-blocking so unless something
immediately fails, EINPROGRESS is returned and we happily leave the loop.
Then when we later attempt to write to the socket, we realize that we're
not connected. No route to host, connection refused etc. I would like
sshd to try another address if possible when this happens. Or in other
words, loop through all candidates until we are absolutely positive we
have established a connection. I think this can be done by selecting
the socket for writing without actually writing anything. I'm happy to
elaborate why this is a real life problem if necessary.
Comment 1 Damien Miller 2003-05-15 18:36:44 AEST 
The fix for Bug #207 may be useful here
Comment 2 Damien Miller 2008-05-09 01:01:36 AEST 
Created attachment 1498 [details]
try subsequent addresses

This patch should fix the bug. (better late than never)
Comment 3 Damien Miller 2008-05-09 01:02:54 AEST 
Target release openssh-5.1
Comment 4 Damien Miller 2008-05-09 15:05:32 AEST 
Fix committed and will be in openssh-5.1:

> CVSROOT:        /cvs
> Module name:    src
> Changes by:     djm@cvs.openbsd.org     2008/05/08 22:55:57
> 
> Modified files:
>         usr.bin/ssh    : channels.c channels.h clientloop.c serverloop.c
> 
> Log message:
> Try additional addresses when connecting to a port forward destination
> whose DNS name resolves to more than one address. The previous behaviour
> was to try the first address and give up.
> 
> Reported by stig AT venaas.com in bz#343
> 
> great feedback and ok markus@
Comment 5 Damien Miller 2008-07-22 12:06:39 AEST 
Mass update RESOLVED->CLOSED after release of openssh-5.1