On Wed, Feb 25, 2015 at 2:30 PM, Garrett Cooper <yaneurabeya_at_gmail.com> wrote: > On Feb 25, 2015, at 14:19, Miguel Clara <miguelmclara_at_gmail.com> wrote: > > ... > > > I noticed this too, but in that case why doesn't it affect all users? > (or all the ones using dnscrypt+local_unbound) maybe something changed in > "NETWORKING" recently? > > > > Hum: > > > https://svnweb.freebsd.org/base/head/etc/rc.d/NETWORKING?r1=275299&r2=278704 > > > > Interesting, as I am using the most recent version which does not > REQUIRE local_unbound > > > > I'm even more confused now :| > > > > > > So it has to come after SERVERS but before local_unbound. But NETWORKING > depends on local_unbound they are both dependent on NEWORKING which has to > be after SERVERS. Can you say fubar! Clearly broken. And this means that > removing SERVERS will re-shuffle the order more appropriately. > > > > It seems that the behavior of rcorder is not as documented as well as > being undefined when circular dependencies occur. The man page says that > rcorder aborts when it encounters a circular dependency, but that is not > the case. It probably is best that it not die, but that leaves things in an > unknown and inconsistant state, which is also a very bad idea. I guess when > a circular dependency is encountered, a dichotomy occurs. > > Now you know why I’m so curious about all of this stuff. > > When I was working on ^/projects/building-blocks, I was able to move most > of these pieces around by changing REQUIRE: to BEFORE:, but I noticed that > it changes the rcorder a bit, so I haven’t been super gung ho in > implementing my change. > > I think there are a couple bugs present on 9-STABLE/10-STABLE/11-CURRENT: > > - Things go awry if named is removed/not installed. > - Things go awry if local_unbound is removed (which would have been the > case if the rc.d script was removed from your system, which existed before > my changes). > - Other rc.d scripts not being present might break assumptions. > > I need to create dummy providers for certain logical stages (DNS is one of > them) to solve part of this problem and provide third parties with a > mechanism that can be depended on (I wish applications were written in a > more robust manner to fail gracefully and retry instead of failing flat on > their face, but as I’ve seen at several jobs, getting developers to fail, > then retry is hard :(…). > > Another short-term hack: > > Install dummy/no-op providers so the ordering is preserved, then remove > the hacks after all of the bugs have been shaken out. > > Thanks! > Garret, Also undocumented (except in rcorder.c) is that the lack of a provider is not an error. This effectively makes a list of providers into an OR. So, for name service the normal list is "named local_unbound unbound" and any will work for ordering and having none is a no-op, so if you don't run any nameserver (or kerberos or whatever provider), it is not an issue. As long as rcorder finds a provider, it will be used to set the order, but the lack of any or all providers just means that the specified provider is ignored and if a REQUIRES or BEFORE lists no existing providers, the statement is simply ignored. The real problem is that there is no defined rule for behavior in the event of a circular dependency and any change to any decision point in the ordering process may change the way the ordering flips. That is why these things are such a royal pain to debug. A change in any rc.d script may cause the ordering of seemingly unrelated scripts to change, perhaps drastically, and the error messages, while not misleading, is only a starting point in tracking this down. This means there may be time bombs that break working ports without their being touched or even re-installed. And the triggering change my, itself be correct. -- Kevin Oberman, Network Engineer, Retired E-mail: rkoberman_at_gmail.comReceived on Thu Feb 26 2015 - 01:08:22 UTC
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