Adding upstream version 3.2.1.upstream/3.2.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 148 insertions, 0 deletions

diff --git a/modules/priming/README.rst b/modules/priming/README.rst
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+++ b/modules/priming/README.rst
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+.. _mod-priming:
+
+Priming module
+--------------
+
+The module for Initializing a DNS Resolver with Priming Queries implemented
+according to :rfc:`8109`. Purpose of the module is to keep up-to-date list of
+root DNS servers and associated IP addresses.
+
+Result of successful priming query replaces root hints distributed with
+the resolver software. Unlike other DNS resolvers, Knot Resolver caches
+result of priming query on disk and keeps the data between restarts until
+TTL expires.
+
+This module is enabled by default and it is not recommended to disable it.
+For debugging purposes you may disable the module by appending
+``modules.unload('priming')`` to your configuration.
diff --git a/modules/priming/priming.lua b/modules/priming/priming.lua
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+++ b/modules/priming/priming.lua
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+-- Module interface
+local ffi = require('ffi')
+
+local priming = {}
+priming.retry_time = 10 * sec -- retry time when priming fail
+
+-- internal state variables and functions
+local internal = {}
+internal.nsset = {}  -- set of resolved nameservers
+internal.min_ttl = 0 -- minimal TTL of NS records
+internal.to_resolve = 0 -- number of pending queries to A or AAAA
+internal.prime = {} -- function triggering priming query
+internal.event = nil -- stores event id
+
+-- Copy hints from nsset table to resolver engine
+-- These addresses replace root hints loaded by default from file.
+-- They are stored outside cache and cache flush will not affect them.
+local function publish_hints(nsset)
+	local roothints = kres.context().root_hints
+	-- reset zone cut and clear address list
+	ffi.C.kr_zonecut_set(roothints, kres.str2dname("."))
+	for dname, addrsets in pairs(nsset) do
+		for i = 0, addrsets:rdcount() - 1 do
+			local rdpt = addrsets:rdata_pt(i)
+			ffi.C.kr_zonecut_add(roothints, dname, rdpt.data, rdpt.len)
+		end
+	end
+end
+
+-- Count A and AAAA addresses in nsset
+local function count_addresses(nsset)
+	local count = 0
+	for _, addrset in pairs(nsset) do
+		count = count + addrset:rdcount()
+	end
+	return count
+end
+
+-- Callback for response from A or AAAA query for root nameservers
+-- address is added to table internal.nsset.
+-- When all response is processed internal.nsset is published in resolver engine
+-- luacheck: no unused args
+local function address_callback(pkt, req)
+	pkt = kres.pkt_t(pkt)
+	-- req = kres.request_t(req)
+	if pkt:rcode() ~= kres.rcode.NOERROR then
+		warn("[priming] cannot resolve address '%s', type: %d", kres.dname2str(pkt:qname()), pkt:qtype())
+	else
+		local section = pkt:rrsets(kres.section.ANSWER)
+		for i = 1, #section do
+			local rrset_new = section[i]
+			if rrset_new.type == kres.type.A or rrset_new.type == kres.type.AAAA then
+				local owner = rrset_new:owner()
+				local rrset_comb = internal.nsset[owner]
+				if rrset_comb == nil then
+					rrset_comb = kres.rrset(nil, rrset_new.type)
+					internal.nsset[owner] = rrset_comb
+				end
+				assert(ffi.istype(kres.rrset, rrset_new))
+				rrset_comb:merge_rdata(rrset_new)
+			end
+		end
+	end
+	internal.to_resolve = internal.to_resolve - 1
+	if internal.to_resolve == 0 then
+		if count_addresses(internal.nsset) == 0 then
+			warn("[priming] cannot resolve any root server address, next priming query in %d seconds", priming.retry_time / sec)
+			internal.event = event.after(priming.retry_time, internal.prime)
+		else
+			publish_hints(internal.nsset)
+			if verbose() then
+				log("[priming] triggered priming query, next in %d seconds", internal.min_ttl)
+			end
+			internal.event = event.after(internal.min_ttl * sec, internal.prime)
+		end
+	end
+end
+
+-- Callback for priming query ('.' NS)
+-- For every NS record creates two separate queries for A and AAAA.
+-- These new queries should be resolved from cache.
+-- luacheck: no unused args
+local function priming_callback(pkt, req)
+	pkt = kres.pkt_t(pkt)
+	-- req = kres.request_t(req)
+	if pkt:rcode() ~= kres.rcode.NOERROR then
+		warn("[priming] cannot resolve '.' NS, next priming query in %d seconds", priming.retry_time / sec)
+		internal.event = event.after(priming.retry_time, internal.prime)
+		return nil
+	end
+	local section = pkt:rrsets(kres.section.ANSWER)
+	for i = 1, #section do
+		local rr = section[i]
+		if rr.type == kres.type.NS then
+			internal.min_ttl = math.min(internal.min_ttl, rr:ttl())
+			internal.to_resolve = internal.to_resolve + 2 * rr.rrs.count
+			for k = 0, rr.rrs.count-1 do
+				local nsname_text = rr:tostring(k)
+				resolve(nsname_text, kres.type.A, kres.class.IN, 0, address_callback)
+				resolve(nsname_text, kres.type.AAAA, kres.class.IN, 0, address_callback)
+			end
+		end
+	end
+end
+
+-- trigger priming query
+function internal.prime()
+	internal.min_ttl = math.max(1, cache.max_ttl()) -- sanity check for disabled cache
+	internal.nsset = {}
+	internal.to_resolve = 0
+	resolve(".", kres.type.NS, kres.class.IN, 0, priming_callback)
+end
+
+function priming.init()
+	if internal.event then
+		error("Priming module is already loaded.")
+	else
+		internal.event = event.after(0 , internal.prime)
+	end
+end
+
+function priming.deinit()
+	if internal.event then
+		event.cancel(internal.event)
+		internal.event = nil
+	end
+end
+
+return priming
diff --git a/modules/priming/priming.mk b/modules/priming/priming.mk
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+++ b/modules/priming/priming.mk
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+priming_SOURCES := priming.lua
+$(call make_lua_module,priming)