Re: git: 8338690a0a43 - main - ip_reass: provide sysctl MIB returning IP fragment TTL

On Sun, Aug 21, 2022 at 12:07:39AM +0200, Michael Tuexen wrote:
M> > commit 8338690a0a43c8b11a382e2160f8eedb9aeecf91
M> > Author:     Gleb Smirnoff <glebius@FreeBSD.org>
M> > AuthorDate: 2022-08-20 20:33:39 +0000
M> > Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
M> > CommitDate: 2022-08-20 20:39:12 +0000
M> > 
M> >    ip_reass: provide sysctl MIB returning IP fragment TTL
M> > 
M> >    For now it is read-only, but eventually the cycle that goes over
M> >    all fragments should be refactored and this MIB should also become
M> >    read/write.
M> > 
M> >    This MIB will allow SNMP daemons to implement MIB-II ipReasmTimeout MIB
M> >    straightfoward.  Right now net-snmp compilation is broken by 1922eb3e9c2.
M> >    The base system bsnmpd is not broken just because it ignored PR_SLOWTIMO,
M> >    and thus always returned incorrectly doubled value for ipReasmTimeout.
M> > ---
M> > sys/netinet/ip_reass.c | 4 ++++
M> > 1 file changed, 4 insertions(+)
M> > 
M> > diff --git a/sys/netinet/ip_reass.c b/sys/netinet/ip_reass.c
M> > index 0420091e0a2a..e581e2e622c7 100644
M> > --- a/sys/netinet/ip_reass.c
M> > +++ b/sys/netinet/ip_reass.c
M> > @@ -167,6 +167,10 @@ SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
M> >     sysctl_maxfragbucketsize, "I",
M> >     "Maximum number of IPv4 fragment reassembly queue entries per bucket");
M> > 
M> > +static u_int ipfragttl = IPFRAGTTL / 2;
M> > +SYSCTL_UINT(_net_inet_ip, OID_AUTO, fragttl, CTLFLAG_RD, &ipfragttl,
M> > +    IPFRAGTTL / 2, "IP fragment life time on reassembly queue");
M> What unit is used? seconds? milliseconds? You might want to state that.
M> What us the semantic of IPFRAGTTL? What is the unit of that constant?

I'll add '(seconds)' to the sysctl description.

The semantic of IPFRAGTTL is ugly. It is number of timeouts, which are 0.5
second. A legacy of PR_SLOWTIMO. This will go away, so is not worth documenting.

-- 
Gleb Smirnoff