freebsd stable - Nov 2019 - syslogd truncating messages on FreeBSD >11.2-R

Hi,

please let me know if there is a better forum for this.

As of 11.3-RELEASE syslogd truncates all forwarded messages to 480 bytes for 
IPV4 and 1180 for IPv6.

The change occurs in the added code:

        switch (f->f_type) {
        case F_FORW:
                /* Truncate messages to RFC 5426 recommended size. */
                dprintf(" %s", f->fu_forw_hname);
                switch (f->fu_forw_addr->ai_addr->sa_family) {
#ifdef INET
                case AF_INET:
                        dprintf(":%d\n",
                           
ntohs(satosin(f->fu_forw_addr->ai_addr)->sin_port));
                        iovlist_truncate(il, 480);
                        break;
#endif

There's more code for IPv6 and the function iovlist_truncate itself.

This change is not turned on by a switch and happens automatically, however I 
can't find it documented in UPDATING or the release notes.  I would have 
thought that any change in default behaviour of the system should at least be 
documented.

Ideally this change would have been implemented via a switch given that the 
RFC mentioned in the code (RFC 5426) does not mandate truncation, but 
recommends it when the network MTU is not known.

What's the best way to reach out to the maintainer to suggest a switch to 
turn on this code?

Thanks,
Scott

On 9/11/2019 2:08 pm, Scott wrote:
> Hi,
> 
> please let me know if there is a better forum for this.
> 
> As of 11.3-RELEASE syslogd truncates all forwarded messages to 480 bytes
for
> IPV4 and 1180 for IPv6.
> 
> The change occurs in the added code:
> 
>          switch (f->f_type) {
>          case F_FORW:
>                  /* Truncate messages to RFC 5426 recommended size. */
>                  dprintf(" %s", f->fu_forw_hname);
>                  switch (f->fu_forw_addr->ai_addr->sa_family) {
> #ifdef INET
>                  case AF_INET:
>                          dprintf(":%d\n",
>                             
ntohs(satosin(f->fu_forw_addr->ai_addr)->sin_port));
>                          iovlist_truncate(il, 480);
>                          break;
> #endif
> 
> There's more code for IPv6 and the function iovlist_truncate itself.
> 
> This change is not turned on by a switch and happens automatically, however
I
> can't find it documented in UPDATING or the release notes.  I would
have
> thought that any change in default behaviour of the system should at least
be
> documented.
> 
> Ideally this change would have been implemented via a switch given that the
> RFC mentioned in the code (RFC 5426) does not mandate truncation, but
> recommends it when the network MTU is not known.
> 
> What's the best way to reach out to the maintainer to suggest a switch
to
> turn on this code?
> 
> Thanks,
> Scott

Hi Scott,

Looks like this came in in base r332510 [1] via:

https://reviews.freebsd.org/D15011

The commit log message and review history may provide additional context 
for the behaviour change (I haven't reviewed them)

I have CC'd the committer on this email, but in the meantime, and if you 
wouldn't mind, it is worth reporting the issue via Bugzilla, so that we 
track it, and so others can find it.

[1] https://svnweb.freebsd.org/changeset/base/332510

--
Regards,

koobs