Re: [PATCH] BUG/MINOR: tcp: don't try to set defaultmss when value is negative

[Willy Tarreau]

On Wed, Feb 12, 2020 at 01:16:15PM +0100, William Dauchy wrote:
>               getsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, &tmpmaxseg, &len);
> -             if (tmpmaxseg != defaultmss && setsockopt(fd, IPPROTO_TCP,
> -                                             TCP_MAXSEG, &defaultmss,
> -                                             sizeof(defaultmss)) == -1) {
> +             if (defaultmss < 0 ||
> +                 (tmpmaxseg != defaultmss &&
> +                  setsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, &defaultmss, 
> sizeof(defaultmss)) == -1)) {
>                       msg = "cannot set MSS";
>                       err |= ERR_WARN;

I'd do it differently so that we neither try nor report an error if
the default mss was not set. Indeed, if it already failed earlier,
we already had an issue, so no need to fail again. So if you agree
I'll change it to :

     if (defaultmss > 0 &&
         tmpmaxseg != defaultmss &&
         setsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, &defaultmss, 
sizeof(defaultmss)) == -1)

Thanks,
Willy