9 files changed, 532 insertions, 0 deletions
diff --git a/modules/view/README.rst b/modules/view/README.rst
new file mode 100644
index 0000000..3fa043a
--- /dev/null
+++ b/modules/view/README.rst
@@ -0,0 +1,89 @@
+.. _mod-view:
+
+Views and ACLs
+--------------
+
+The :ref:`policy <mod-policy>` module implements policies for global query matching, e.g. solves "how to react to certain query".
+This module combines it with query source matching, e.g. "who asked the query". This allows you to create personalized blacklists, filters and ACLs.
+
+There are two identification mechanisms:
+
+* ``addr``
+  - identifies the client based on his subnet
+* ``tsig``
+  - identifies the client based on a TSIG key name (only for testing purposes, TSIG signature is not verified!)
+
+View module allows you to combine query source information with :ref:`policy <mod-policy>` rules.
+
+.. code-block:: lua
+
+	view:addr('10.0.0.1', policy.suffix(policy.TC, policy.todnames({'example.com'})))
+
+This example will force given client to TCP for names in ``example.com`` subtree.
+You can combine view selectors with RPZ_ to create personalized filters for example.
+
+.. warning::
+
+	Beware that cache is shared by *all* requests.  For example, it is safe
+	to refuse answer based on who asks the resolver, but trying to serve
+	different data to different clients will result in unexpected behavior.
+	Setups like **split-horizon** which depend on isolated DNS caches
+        are explicitly not supported.
+
+
+Example configuration
+^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: lua
+
+	-- Load modules
+	modules = { 'view' }
+	-- Whitelist queries identified by TSIG key
+	view:tsig('\5mykey', policy.all(policy.PASS))
+	-- Block local clients (ACL like)
+	view:addr('127.0.0.1', policy.all(policy.DENY))
+	-- Drop queries with suffix match for remote client
+	view:addr('10.0.0.0/8', policy.suffix(policy.DROP, policy.todnames({'xxx'})))
+	-- RPZ for subset of clients
+	view:addr('192.168.1.0/24', policy.rpz(policy.PASS, 'whitelist.rpz'))
+	-- Do not try this - it will pollute cache and surprise you!
+	-- view:addr('10.0.0.0/8', policy.all(policy.FORWARD('2001:DB8::1')))
+	-- Drop everything that hasn't matched
+	view:addr('0.0.0.0/0', policy.all(policy.DROP))
+
+
+Rule order
+^^^^^^^^^^
+
+The current implementation is best understood as three separate rule chains:
+vanilla ``policy.add``, ``view:tsig`` and ``view:addr``.
+For each request the rules in these chains get tried one by one until a :ref:`non-chain policy action <mod-policy-actions>` gets executed.
+
+By default :ref:`policy module <mod-policy>` acts before ``view`` module due to ``policy`` being loaded by default. If you want to intermingle universal rules with ``view:addr``, you may simply wrap the universal policy rules in view closure like this:
+
+.. code-block:: lua
+
+    view:addr('0.0.0.0/0', policy.<rule>) -- and
+    view:addr('::0/0',     policy.<rule>)
+
+
+Properties
+^^^^^^^^^^
+
+.. function:: view:addr(subnet, rule)
+
+  :param subnet: client subnet, i.e. ``10.0.0.1``
+  :param rule: added rule, i.e. ``policy.pattern(policy.DENY, '[0-9]+\2cz')``
+  
+  Apply rule to clients in given subnet.
+
+.. function:: view:tsig(key, rule)
+
+  :param key: client TSIG key domain name, i.e. ``\5mykey``
+  :param rule: added rule, i.e. ``policy.pattern(policy.DENY, '[0-9]+\2cz')``
+  
+  Apply rule to clients with given TSIG key.
+
+  .. warning:: This just selects rule based on the key name, it doesn't verify the key or signature yet.
+
+.. _RPZ: https://dnsrpz.info/
diff --git a/modules/view/addr.test.integr/deckard.yaml b/modules/view/addr.test.integr/deckard.yaml
new file mode 100644
index 0000000..ac2792d
--- /dev/null
+++ b/modules/view/addr.test.integr/deckard.yaml
@@ -0,0 +1,12 @@
+programs:
+- name: kresd
+  binary: kresd
+  additional:
+    - -f
+    - "1"
+  templates:
+    - modules/view/addr.test.integr/kresd_config.j2
+    - tests/hints_zone.j2
+  configs:
+    - config
+    - hints
diff --git a/modules/view/addr.test.integr/kresd_config.j2 b/modules/view/addr.test.integr/kresd_config.j2
new file mode 100644
index 0000000..f56430a
--- /dev/null
+++ b/modules/view/addr.test.integr/kresd_config.j2
@@ -0,0 +1,53 @@
+{% raw %}
+modules.load('view < policy')
+
+view:addr('127.0.0.0/24', policy.suffix(policy.DENY_MSG("addr 127.0.0.0/24 matched com"),{"\3com\0"}))
+view:addr('127.0.0.0/24', policy.suffix(policy.DENY_MSG("addr 127.0.0.0/24 matched net"),{"\3net\0"}))
+policy.add(policy.all(policy.FORWARD('1.2.3.4')))
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+_hint_root_file('hints')
+cache.size = 2*MB
+verbose(true)
+{% endraw %}
+
+net = { '{{SELF_ADDR}}' }
+
+
+{% if QMIN == "false" %}
+option('NO_MINIMIZE', true)
+{% else %}
+option('NO_MINIMIZE', false)
+{% endif %}
+
+
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.count() == 0)
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+assert(net.list()['{{SELF_ADDR}}'])
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
diff --git a/modules/view/addr.test.integr/module_view_addr.rpl b/modules/view/addr.test.integr/module_view_addr.rpl
new file mode 100644
index 0000000..9e65d28
--- /dev/null
+++ b/modules/view/addr.test.integr/module_view_addr.rpl
@@ -0,0 +1,78 @@
+; config options
+	stub-addr: 1.2.3.4
+	query-minimization: off
+CONFIG_END
+
+SCENARIO_BEGIN view:addr test
+
+RANGE_BEGIN 0 110
+	ADDRESS 1.2.3.4
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+example.cz. IN A
+SECTION ANSWER
+example.cz. IN A 5.6.7.8
+ENTRY_END
+
+RANGE_END
+
+; policy module loaded before view module must take precedence before view
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+example.cz. IN A
+ENTRY_END
+
+STEP 20 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH flags rcode question answer
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+example.cz. IN A
+SECTION ANSWER
+example.cz. IN A 5.6.7.8
+ENTRY_END
+
+; blocked by view:addr + inner policy.suffix com
+; NXDOMAIN expected
+STEP 30 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+example.com. IN A
+ENTRY_END
+
+STEP 31 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode question rcode additional
+REPLY QR RD RA AA NXDOMAIN
+SECTION QUESTION
+example.com. IN A
+SECTION ADDITIONAL
+explanation.invalid. 10800 IN TXT "addr 127.0.0.0/24 matched com"
+ENTRY_END
+
+; blocked by view:addr + inner policy.suffix net
+; second view rule gets executed if policy in preceding view rule did not match
+STEP 32 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+example.net. IN A
+ENTRY_END
+
+STEP 33 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode question rcode additional
+REPLY QR RD RA AA NXDOMAIN
+SECTION QUESTION
+example.net. IN A
+SECTION ADDITIONAL
+explanation.invalid. 10800 IN TXT "addr 127.0.0.0/24 matched net"
+ENTRY_END
+
+SCENARIO_END
diff --git a/modules/view/tsig.test.integr/deckard.yaml b/modules/view/tsig.test.integr/deckard.yaml
new file mode 100644
index 0000000..bc89906
--- /dev/null
+++ b/modules/view/tsig.test.integr/deckard.yaml
@@ -0,0 +1,12 @@
+programs:
+- name: kresd
+  binary: kresd
+  additional:
+    - -f
+    - "1"
+  templates:
+    - modules/view/tsig.test.integr/kresd_config.j2
+    - tests/hints_zone.j2
+  configs:
+    - config
+    - hints
diff --git a/modules/view/tsig.test.integr/kresd_config.j2 b/modules/view/tsig.test.integr/kresd_config.j2
new file mode 100644
index 0000000..6a0952e
--- /dev/null
+++ b/modules/view/tsig.test.integr/kresd_config.j2
@@ -0,0 +1,55 @@
+{% raw %}
+modules.load('view')
+print(table_print(modules.list()))
+
+view:tsig('\8testkey1\0', policy.suffix(policy.DENY_MSG("TSIG key testkey1 matched com"),{"\3com\0"}))
+view:tsig('\8testkey1\0', policy.suffix(policy.DENY_MSG("TSIG key testkey1 matched net"),{"\3net\0"}))
+view:tsig('\7testkey\0', policy.suffix(policy.DENY_MSG("TSIG key testkey matched example"),{"\7example\0"}))
+policy.add(policy.all(policy.FORWARD('1.2.3.4')))
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+_hint_root_file('hints')
+cache.size = 2*MB
+verbose(true)
+{% endraw %}
+
+net = { '{{SELF_ADDR}}' }
+
+
+{% if QMIN == "false" %}
+option('NO_MINIMIZE', true)
+{% else %}
+option('NO_MINIMIZE', false)
+{% endif %}
+
+
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.count() == 0)
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+assert(net.list()['{{SELF_ADDR}}'])
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
diff --git a/modules/view/tsig.test.integr/module_view_tsig.rpl b/modules/view/tsig.test.integr/module_view_tsig.rpl
new file mode 100644
index 0000000..8abceb5
--- /dev/null
+++ b/modules/view/tsig.test.integr/module_view_tsig.rpl
@@ -0,0 +1,113 @@
+; config options
+	stub-addr: 1.2.3.4
+CONFIG_END
+
+SCENARIO_BEGIN view:tsig test
+
+RANGE_BEGIN 0 110
+	ADDRESS 1.2.3.4
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+example.cz. IN A
+SECTION ANSWER
+example.cz. IN A 5.6.7.8
+ENTRY_END
+
+RANGE_END
+
+RANGE_BEGIN 0 110
+	ADDRESS 192.0.2.1
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+example.net. IN A
+SECTION ANSWER
+example.net. IN A 6.6.6.6
+ENTRY_END
+RANGE_END
+
+; policy fallback (no view matched, policy is behind view module)
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD
+TSIG testkey +Cdjlkef9ZTSeixERZ433Q==
+SECTION QUESTION
+example.cz. IN A
+ENTRY_END
+
+STEP 20 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH flags rcode question answer
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+example.cz. IN A
+SECTION ANSWER
+example.cz. IN A 5.6.7.8
+ENTRY_END
+
+; blocked by view:tsig testkey1 + inner policy.suffix com
+; NXDOMAIN expected
+STEP 30 QUERY
+ENTRY_BEGIN
+REPLY RD
+TSIG testkey1 +Cdjlkef9ZTSeixERZ433Q==
+SECTION QUESTION
+example.com. IN A
+ENTRY_END
+
+STEP 31 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode question rcode additional
+REPLY QR RD RA AA NXDOMAIN
+SECTION QUESTION
+example.com. IN A
+SECTION ADDITIONAL
+explanation.invalid. 10800 IN TXT "TSIG key testkey1 matched com"
+ENTRY_END
+
+; blocked by view:tsig testkey1 + inner policy.suffix net
+; second view rule gets executed if policy in preceding view rule did not match
+STEP 32 QUERY
+ENTRY_BEGIN
+REPLY RD
+TSIG testkey1 +Cdjlkef9ZTSeixERZ433Q==
+SECTION QUESTION
+example.net. IN A
+ENTRY_END
+
+STEP 33 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode question rcode additional
+REPLY QR RD RA AA NXDOMAIN
+SECTION QUESTION
+example.net. IN A
+SECTION ADDITIONAL
+explanation.invalid. 10800 IN TXT "TSIG key testkey1 matched net"
+ENTRY_END
+
+; blocked by view:tsig testkey + inner policy.suffix example (different key)
+; third view rule gets executed if policy in preceding view rule did not match
+STEP 34 QUERY
+ENTRY_BEGIN
+REPLY RD
+TSIG testkey +Cdjlkef9ZTSeixERZ433Q==
+SECTION QUESTION
+example. IN A
+ENTRY_END
+
+STEP 35 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode question rcode additional
+REPLY QR RD RA AA NXDOMAIN
+SECTION QUESTION
+example. IN A
+SECTION ADDITIONAL
+explanation.invalid. 10800 IN TXT "TSIG key testkey matched example"
+ENTRY_END
+
+SCENARIO_END
diff --git a/modules/view/view.lua b/modules/view/view.lua
new file mode 100644
index 0000000..41157eb
--- /dev/null
+++ b/modules/view/view.lua
@@ -0,0 +1,118 @@
+local kres = require('kres')
+local ffi = require('ffi')
+local C = ffi.C
+
+-- Module declaration
+local view = {
+	key = {}, -- map from :owner() to list of policy rules
+	src = {},
+	dst = {},
+}
+
+-- @function View based on TSIG key name.
+function view.tsig(_, tsig, rule)
+	if view.key[tsig] == nil then
+		view.key[tsig] = { rule }
+	else
+		table.insert(view.key[tsig], rule)
+	end
+end
+
+-- @function View based on source IP subnet.
+function view.addr(_, subnet, rules, dst)
+	local subnet_cd = ffi.new('char[16]')
+	local family = C.kr_straddr_family(subnet)
+	local bitlen = C.kr_straddr_subnet(subnet_cd, subnet)
+	local t = {family, subnet_cd, bitlen, rules}
+	table.insert(dst and view.dst or view.src, t)
+	return t
+end
+
+-- @function Match IP against given subnet
+local function match_subnet(family, subnet, bitlen, addr)
+	return (family == addr:family()) and (C.kr_bitcmp(subnet, addr:ip(), bitlen) == 0)
+end
+
+-- @function Execute a policy callback (may be nil);
+-- return boolean: whether to continue trying further rules.
+local function execute(state, req, match_cb)
+	if match_cb == nil then return false end
+	local action = match_cb(req, req:current())
+	if action == nil then return false end
+	local next_state = action(state, req)
+	if next_state then    -- Not a chain rule,
+		req.state = next_state
+		return true
+	else
+		return false
+	end
+end
+
+-- @function Try all the rules in order, until a non-chain rule gets executed.
+local function evaluate(state, req)
+	-- Try :tsig rules first.
+	local client_key = req.qsource.packet.tsig_rr
+	local match_cbs = (client_key ~= nil) and view.key[client_key:owner()] or {}
+	for _, match_cb in ipairs(match_cbs) do
+		if execute(state, req, match_cb) then return end
+	end
+	-- Then try :addr by the source.
+	if req.qsource.addr ~= nil then
+		for i = 1, #view.src do
+			local pair = view.src[i]
+			if match_subnet(pair[1], pair[2], pair[3], req.qsource.addr) then
+				local match_cb = pair[4]
+				if execute(state, req, match_cb) then return end
+			end
+		end
+	-- Finally try :addr by the destination.
+	elseif req.qsource.dst_addr ~= nil then
+		for i = 1, #view.dst do
+			local pair = view.dst[i]
+			if match_subnet(pair[1], pair[2], pair[3], req.qsource.dst_addr) then
+				local match_cb = pair[4]
+				if execute(state, req, match_cb) then return end
+			end
+		end
+	end
+end
+
+-- @function Return policy based on source address
+function view.rule_src(action, subnet)
+	local subnet_cd = ffi.new('char[16]')
+	local family = C.kr_straddr_family(subnet)
+	local bitlen = C.kr_straddr_subnet(subnet_cd, subnet)
+	return function(req, _)
+		local addr = req.qsource.addr
+		if addr ~= nil and match_subnet(family, subnet_cd, bitlen, addr) then
+			return action
+		end
+	end
+end
+
+-- @function Return policy based on destination address
+function view.rule_dst(action, subnet)
+	local subnet_cd = ffi.new('char[16]')
+	local family = C.kr_straddr_family(subnet)
+	local bitlen = C.kr_straddr_subnet(subnet_cd, subnet)
+	return function(req, _)
+		local addr = req.qsource.dst_addr
+		if addr ~= nil and match_subnet(family, subnet_cd, bitlen, addr) then
+			return action
+		end
+	end
+end
+
+-- @function Module layers
+view.layer = {
+	begin = function(state, req)
+		-- Don't act on "resolved" cases.
+		if bit.band(state, bit.bor(kres.FAIL, kres.DONE)) ~= 0 then return state end
+
+		req = kres.request_t(req)
+		evaluate(state, req)
+		return req.state
+	end
+}
+
+return view
diff --git a/modules/view/view.mk b/modules/view/view.mk
new file mode 100644
index 0000000..47b752d
--- /dev/null
+++ b/modules/view/view.mk
@@ -0,0 +1,2 @@
+view_SOURCES := view.lua
+$(call make_lua_module,view)