[Project] Preliminary SPF plugin in Lua

src/plugins/lua/spf.lua

@@ -0,0 +1,147 @@
+--[[
+Copyright (c) 2019, Vsevolod Stakhov <vsevolod@highsecure.ru>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+]]--
+
+local N = "spf"
+local lua_util = require "lua_util"
+local rspamd_spf = require "rspamd_spf"
+local bit = require "bit"
+
+if confighelp then
+  rspamd_config:add_example(nil, N,
+      'Performs SPF checks',
+      [[
+spf {
+  # Enable module
+  enabled = true
+  # Number of elements in the cache of parsed SPF records
+  spf_cache_size = 2048;
+  # Default max expire for an element in this cache
+  spf_cache_expire = 1d;
+  # Whitelist IPs from checks
+  whitelist = "/path/to/some/file";
+  # Maximum number of recursive DNS subrequests (e.g. includes chanin length)
+  max_dns_nesting = 10;
+  # Maximum count of DNS requests per record
+  max_dns_requests = 30;
+  # Minimum TTL enforced for all elements in SPF records
+  min_cache_ttl = 5m;
+  # Disable all IPv6 lookups
+  disable_ipv6 = false;
+}
+  ]])
+  return
+end
+
+local symbols = {
+  fail = "R_SPF_FAIL",
+  softfail = "R_SPF_SOFTFAIL",
+  neutral = "R_SPF_NEUTRAL",
+  allow = "R_SPF_ALLOW",
+  dnsfail = "R_SPF_DNSFAIL",
+  permfail = "R_SPF_PERMFAIL",
+  na = "R_SPF_NA",
+}
+
+local default_config = {
+  spf_cache_size = 2048,
+  max_dns_nesting = 10,
+  max_dns_requests = 30,
+  whitelist = nil,
+  min_cache_ttl = 60 * 5,
+  disable_ipv6 = false,
+  symbols = symbols
+}
+
+local local_config = rspamd_config:get_all_opt('spf')
+
+if local_config then
+  local_config = lua_util.override_defaults(default_config, local_config)
+else
+  local_config = default_config
+end
+
+local function spf_check_callback(task)
+  local function flag_to_symbol(fl)
+    if bit.band(fl, rspamd_spf.flags.temp_fail) ~= 0 then
+      return local_config.symbols.temp_fail
+    elseif bit.band(fl, rspamd_spf.flags.perm_fail) ~= 0 then
+      return local_config.symbols.perm_fail
+    elseif bit.band(fl, rspamd_spf.flags.na) ~= 0 then
+      return local_config.symbols.na
+    end
+
+    return 'SPF_UNKNOWN'
+  end
+
+  local function policy_decode(res)
+    if res == rspamd_spf.policy.fail then
+      return local_config.symbols.fail,'-'
+    elseif res == rspamd_spf.policy.pass then
+      return local_config.symbols.allow,'+'
+    elseif res == rspamd_spf.policy.soft_fail then
+      return local_config.symbols.softfail,'~'
+    elseif res == rspamd_spf.policy.neutral then
+      return local_config.symbols.neutral,'?'
+    end
+
+    return 'SPF_UNKNOWN','?'
+  end
+
+  local function spf_resolved_cb(record, flags, err)
+    if record then
+      local result, flag_or_policy, error_or_addr = record:check_ip(task:get_from_ip())
+
+      if result then
+        local sym,code = policy_decode(flag_or_policy)
+        local opt = string.format('%s%s', code, error_or_addr.str or '???')
+        if bit.band(flags, rspamd_spf.flags.cached) ~= 0 then
+          opt = opt .. ':c'
+        end
+        task:insert_result(sym, 1.0, opt)
+      else
+        local sym = flag_to_symbol(flag_or_policy)
+        task:insert_result(sym, 1.0, error_or_addr)
+      end
+    else
+      local sym = flag_to_symbol(flags)
+      task:insert_result(sym, 1.0, err)
+    end
+  end
+
+  rspamd_spf.resolve(task, spf_resolved_cb)
+end
+
+-- Register all symbols and init rspamd_spf library
+rspamd_spf.config(local_config)
+local sym_id = rspamd_config:register_symbol{
+  name = 'SPF_CHECK',
+  type = 'callback',
+  flags = 'fine,empty',
+  groups = {'policies','spf'},
+  score = 0.0,
+  callback = spf_check_callback
+}
+
+for _,sym in pairs(local_config.symbols) do
+  rspamd_config:register_symbol{
+    name = sym,
+    type = 'virtual',
+    parent = sym_id,
+    groups = {'policies', 'spf'},
+  }
+end
+
+