kern/166458: bind() incorrectly interprets SO_REUSEADDR option as also implying SO_REUSEPORT on FreeBSD

[Sean Bruno]

>Number:         166458
>Category:       kern
>Synopsis:       bind() incorrectly interprets SO_REUSEADDR option as also implying SO_REUSEPORT on FreeBSD
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Mar 28 01:00:25 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Sean Bruno
>Release:        9.0
>Organization:
Yahoo! Inc
>Environment:
FreeBSD xxxxxxxxxxxxx 9.0-RELEASE FreeBSD 9.0-RELEASE #3: Tue Dec 27 14:14:29 PST 2011     root at build9x64.pcbsd.org:/usr/obj/builds/amd64/pcbsd-build90/fbsd-source/9.0/sys/GENERIC  amd64
>Description:
<attempting to duplicate internal bug and loop in submitter>

<There> ... seems to be a bug in FreeBSD when specifying port number 0 in the 
socket address passed to the bind system call in order to let the kernel
select a free port number.

The semantics of SO_REUSEADDR is inconsistently implemented on FreeBSD.

FreeBSD 4 jail environment (on a FreeBSD 4 host):

dev-tegge:~$ ./bindbug 
serversock addr is 10.76.250.174:40328
dup bind: Address already in use
This error was expected, tried to bind to used addr/port
dup2 bind: Address already in use
This error was expected, tried to bind to used port without SO_REUSEPORT
autosock addr is 10.76.250.174:40328
bug triggered, port number conflict on sockets without SO_REUSEPORT
listen succeded after implicitly overlapping port bind

FreeBSD 6 host enironment:

tegge-store1:~:$ ./bindbug 
serversock addr is 127.0.0.1:59073
dup bind: Address already in use
This error was expected, tried to bind to used addr/port
BUG: binding duplicate socket to server port succeeded
dup2sock addr is 0.0.0.0:59073
overlapping explicit bind to same port number succeeded without SO_REUSEPORT
listen succeeded after explicitly overlapping port bind
autosock addr is 0.0.0.0:59073
bug triggered, port number conflict on sockets without SO_REUSEPORT
listen succeded after implicitly overlapping port bind

RHEL4 host environment:

[tegge at dell-bl1s3 ~]$ time ./bindbug 
serversock addr is 127.0.0.1:43270
dup bind: Address already in use
This error was expected, tried to bind to used addr/port
dup2 bind: Address already in use
This error was expected, tried to bind to used port without SO_REUSEPORT
bug not triggered after 16777216 iterations

real    1m12.753s
user    0m4.695s
sys     1m8.037s
>How-To-Repeat:
Use test code that is attached, compile and run on a fbsd box vs a linux box.

test case is at http://people.freebsd.org/~sbruno/bind_test.c
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: