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-rw-r--r--modules/prefill/prefill.lua199
1 files changed, 199 insertions, 0 deletions
diff --git a/modules/prefill/prefill.lua b/modules/prefill/prefill.lua
new file mode 100644
index 0000000..f4a4288
--- /dev/null
+++ b/modules/prefill/prefill.lua
@@ -0,0 +1,199 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+local ffi = require('ffi')
+
+local rz_url = "https://www.internic.net/domain/root.zone"
+local rz_local_fname = "root.zone"
+local rz_ca_file = nil
+local rz_event_id = nil
+
+local rz_default_interval = 86400
+local rz_https_fail_interval = 600
+local rz_import_error_interval = 600
+local rz_cur_interval = rz_default_interval
+local rz_interval_randomizer_limit = 10
+local rz_interval_threshold = 5
+local rz_interval_min = 3600
+
+local rz_first_try = true
+
+local prefill = {}
+
+-- hack for circular dependency between timer() and fill_cache()
+local forward_references = {}
+
+local function stop_timer()
+ if rz_event_id then
+ event.cancel(rz_event_id)
+ rz_event_id = nil
+ end
+end
+
+local function timer()
+ stop_timer()
+ worker.bg_worker.cq:wrap(forward_references.fill_cache)
+end
+
+local function restart_timer(after)
+ stop_timer()
+ rz_event_id = event.after(after * sec, timer)
+end
+
+local function display_delay(time)
+ local days = math.floor(time / 86400)
+ local hours = math.floor((time % 86400) / 3600)
+ local minutes = math.floor((time % 3600) / 60)
+ local seconds = math.floor(time % 60)
+ if days > 0 then
+ return string.format("%d days %02d hours", days, hours)
+ elseif hours > 0 then
+ return string.format("%02d hours %02d minutes", hours, minutes)
+ elseif minutes > 0 then
+ return string.format("%02d minutes %02d seconds", minutes, seconds)
+ end
+ return string.format("%02d seconds", seconds)
+end
+
+-- returns: number of seconds the file is valid for
+-- 0 indicates immediate download
+local function get_file_ttl(fname)
+ local mtime = tonumber(ffi.C.kr_file_mtime(fname))
+
+ if mtime > 0 then
+ local age = os.time() - mtime
+ return math.max(
+ rz_cur_interval - age,
+ 0)
+ else
+ return 0 -- file does not exist, download now
+ end
+end
+
+local function download(url, fname)
+ local kluautil = require('kluautil')
+ local file, rcode, errmsg
+ file, errmsg = io.open(fname, 'w')
+ if not file then
+ error(string.format("[prefil] unable to open file %s (%s)",
+ fname, errmsg))
+ end
+
+ log_info(ffi.C.LOG_GRP_PREFILL, "downloading root zone to file %s ...", fname)
+ rcode, errmsg = kluautil.kr_https_fetch(url, file, rz_ca_file)
+ if rcode == nil then
+ error(string.format("[prefil] fetch of `%s` failed: %s", url, errmsg))
+ end
+
+ file:close()
+end
+
+local function import(fname)
+ local ret = ffi.C.zi_zone_import({
+ zone_file = fname,
+ time_src = ffi.C.ZI_STAMP_MTIM, -- the file might be slightly older
+ })
+ if ret == 0 then
+ log_info(ffi.C.LOG_GRP_PREFILL, "zone successfully parsed, import started")
+ else
+ error(string.format(
+ "[prefil] zone import failed: %s", ffi.C.knot_strerror(ret)
+ ))
+ end
+end
+
+function forward_references.fill_cache()
+ local file_ttl = get_file_ttl(rz_local_fname)
+
+ if file_ttl > rz_interval_threshold then
+ log_info(ffi.C.LOG_GRP_PREFILL, "root zone file valid for %s, reusing data from disk",
+ display_delay(file_ttl))
+ else
+ local ok, errmsg = pcall(download, rz_url, rz_local_fname)
+ if not ok then
+ rz_cur_interval = rz_https_fail_interval
+ - math.random(rz_interval_randomizer_limit)
+ log_info(ffi.C.LOG_GRP_PREFILL, "cannot download new zone (%s), "
+ .. "will retry root zone download in %s",
+ errmsg, display_delay(rz_cur_interval))
+ restart_timer(rz_cur_interval)
+ os.remove(rz_local_fname)
+ return
+ end
+ file_ttl = rz_default_interval
+ end
+ -- file is up to date, import
+ -- import/filter function gets executed after resolver/module
+ local ok, errmsg = pcall(import, rz_local_fname)
+ if not ok then
+ if rz_first_try then
+ rz_first_try = false
+ rz_cur_interval = 1
+ else
+ rz_cur_interval = rz_import_error_interval
+ - math.random(rz_interval_randomizer_limit)
+ end
+ log_info(ffi.C.LOG_GRP_PREFILL, "root zone import failed (%s), retry in %s",
+ errmsg, display_delay(rz_cur_interval))
+ else
+ -- re-download before TTL expires
+ rz_cur_interval = (file_ttl - rz_interval_threshold
+ - math.random(rz_interval_randomizer_limit))
+ log_info(ffi.C.LOG_GRP_PREFILL, "root zone refresh in %s",
+ display_delay(rz_cur_interval))
+ end
+ restart_timer(rz_cur_interval)
+end
+
+function prefill.deinit()
+ stop_timer()
+end
+
+-- process one item from configuration table
+-- right now it supports only root zone because
+-- prefill module uses global variables
+local function config_zone(zone_cfg)
+ if zone_cfg.interval then
+ zone_cfg.interval = tonumber(zone_cfg.interval)
+ if zone_cfg.interval < rz_interval_min then
+ error(string.format('[prefil] refresh interval %d s is too short, '
+ .. 'minimal interval is %d s',
+ zone_cfg.interval, rz_interval_min))
+ end
+ rz_default_interval = zone_cfg.interval
+ rz_cur_interval = zone_cfg.interval
+ end
+
+ rz_ca_file = zone_cfg.ca_file
+
+ if not zone_cfg.url or not string.match(zone_cfg.url, '^https://') then
+ error('[prefil] option url must contain a '
+ .. 'https:// URL of a zone file')
+ else
+ rz_url = zone_cfg.url
+ end
+end
+
+function prefill.config(config)
+ if config == nil then return end -- e.g. just modules = { 'prefill' }
+ local root_configured = false
+ if type(config) ~= 'table' then
+ error('[prefil] configuration must be in table '
+ .. '{owner name = {per-zone config}}')
+ end
+ for owner, zone_cfg in pairs(config) do
+ if owner ~= '.' then
+ error('[prefil] only root zone can be imported '
+ .. 'at the moment')
+ else
+ config_zone(zone_cfg)
+ root_configured = true
+ end
+ end
+ if not root_configured then
+ error('[prefil] this module version requires configuration '
+ .. 'for root zone')
+ end
+
+ restart_timer(0) -- start now
+end
+
+return prefill