"view" Behavior Seems Inconsistent With Documentation

Jeff Kletsky unbound at allycomm.com
Sat Aug 25 21:53:46 UTC 2018

I've read through both the unbound.conf(5) man page and 
unbound.conf.sample for unbound Version 1.7.0 many times and am finding 
it hard to understand the logic behind how a specific query is resolved 
against a view and global data alone, not to mention my eventual desire 
to include stub/forwarded zones into the mix. Most of what an Internet 
search on views in unbound discusses Python-driven approaches, not the 
more recent, native implementation.

First, are there any other resources on how the logic among the various 
sources (view local data, view stub/forwarders, global stub/forwarders, 
global local data, external authoritative DNS) for getting an "answer" 
is intended to work?

Functional specs, design docs, or a pointer to the code would be 
generally helpful.

In the minimal test case that returns unexpected results, the goal is 
that there is "public" data that all subnets care resolve, a "private" 
name that all subnets should get the same value for (gld.example.com), 
and another name that a specific subnet should get a different answer 
that the other subnets, overriding the "public" value (maps.example.com).

(This can be tested by substituting example.com for an appropriate 
domain that supports the "maps" host name.)

As I understand the view-first directive it is "use the view's local 
data first, if not present, then check as if the request was made at the 
global level". I would expect this to check the global local data.

        *view-first:*  /<yes/  /or/  /no>/
               If  enabled,  it  attempts  to  use  the  global  local-zone and
               local-data if there is no match in the  view  specific  options.
               The default is no.


* most-anything.example.com resolved by public example.com DNS
* gld.example.com resolved by "global, local" data in unbound (local 
host names with no public DNS)
* maps.example.com resolved by
     * global, local data for many subnets
     * view-specific data for some other subnets

However, when I configure

local-zone: "example.com." typetransparent

local-data: "gld.example.com.    A"
local-data: "maps.example.com.    A"

access-control-view:    "classC"

     name: "classC"
     view-first: yes
     local-zone: "example.com." typetransparent
     local-data: "maps.example.com.    A"

If I query from an address *not* on the subnet, the 
results are as expected:

www.example.com    (resolved by example.com's DNS)

If I query from an address in the subnet ("in" the view), 
it looks like the global data isn't consulted for gld.example.com

www.example.com    (resolved by example.com's DNS)
gld.example.com    NXDOMAIN from example.com's DNS (expected 
from "global" data)
maps.example.com (as expected from the view)

Changing to view-first: no (or omitting it completely) does not change 
the behavior.

Changing the view's local-zone to static (thinking that the view might 
have tried external resolution before deferring to the global zone 
definition) ends up with an NXDOMAIN result for all but maps.example.com 
from the unbound instance (no authority section)..

     name: "classC"
     view-first: yes
     local-zone: "example.com." static
     local-data: "maps.example.com.    A"

www.example.com    NXDOMAIN (expected to be resolved by example.com's DNS)
gld.example.com    NXDOMAIN (expected from "global" data)
maps.example.com (as expected from the view)

(Yes, this simple, two-name configuration could be replicated in the 
view, but the target operational configuration involves many more zones, 
names and views.)

What am I missing in my thinking, in my configuration?



FreeBSD 11.1-RELEASE-p13 #9

Version 1.7.0
linked libs: libevent 2.1.8-stable (it uses kqueue), OpenSSL 
1.0.2k-freebsd  26 Jan 2017
linked modules: dns64 respip validator iterator

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