Re: bind(2) fails on 13.0-STABLE when sin_family is 0

From: Bakul Shah <bakul_at_iitbombay.org>
Date: Fri, 28 May 2021 15:21:15 -0700
On May 28, 2021, at 3:12 PM, Mark Johnston <markj_at_freebsd.org> wrote:
> 
> On Fri, May 28, 2021 at 02:40:26PM -0700, Bakul Shah wrote:
>> ttcp runs fine on 13.0-RELEASE but fails on -stable.
>> 
>> The culprit seems to be bind(2). Running ttcp under gdb:
>> 
>> $ gdb a.out
>> Reading symbols from a.out...
>> (gdb) b 295
>> Breakpoint 1 at 0x203127: file ttcp.c, line 295.
>> (gdb) run -s -r
>> Starting program: /usr/ports/benchmarks/ttcp/work/ttcp-1.12_2/a.out -s -r
>> ttcp-r: buflen=8192, nbuf=2048, align=16384/0, port=5001  tcp
>> ttcp-r: socket
>> 
>> Breakpoint 1, main (argc=3, argv=0x7fffffffd9b0) at ttcp.c:295
>> 295             if (bind(fd, (struct sockaddr *) &sinme, sizeof(sinme)) < 0)
>> (gdb) p/x sinme
>> $1 = {sin_len = 0x0, sin_family = 0x0, sin_port = 0x8913, sin_addr = {
>>   s_addr = 0x0}, sin_zero = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}
>> (gdb) n
>> 296                     err("bind");
>> (gdb) p errno
>> $2 = 47
>> 
>> 
>> $ errno 47
>> #define EAFNOSUPPORT    47              /* Address family not supported by protocol family */
>> 
>> Did something change post 13.0-RELEASE that requires specifying sin_family?
>> Thanks!
> 
> Yes, some changes were made recently to make sockaddr validation
> stricter.  Several other operating systems also have this requirement.
> Linux seems to be a bit more relaxed in that AF_UNSPEC (0) is permitted
> if and only if the bind address is INADDR_ANY, which is the case here.
> 
> Since 2001 the benchmarks/ttcp port has carried a patch to specify
> sin_family.  Is there some reason it cannot be used here?  I don't
> object to re-allowing ttcp's unpatched behaviour if necessary.

The patch was only for the transmit case. Making it unconditional fixed it.
I asked mainly because I was surprised and wanted to make sure this was an
intended change.

Thanks for your response!

-- Bakul
Received on Fri May 28 2021 - 22:21:15 UTC

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