Add preliminary version of DMARC plugin.

src/plugins/lua/dmarc.lua

@@ -0,0 +1,196 @@
+--[[
+Copyright (c) 2011-2015, Vsevolod Stakhov <vsevolod@highsecure.ru>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+]]--
+
+-- Dmarc policy filter
+
+local rspamd_regexp = require "rspamd_regexp"
+local rspamd_logger = require "rspamd_logger"
+local rspamd_redis = require "rspamd_redis"
+local upstream_list = require "rspamd_upstream_list"
+local dumper = require 'pl.pretty'.dump
+
+local symbols = {
+  spf_allow_symbol = 'R_SPF_ALLOW',
+  spf_deny_symbol = 'R_SPF_FAIL',
+  spf_softfail_symbol = 'R_SPF_SOFTFAIL',
+  spf_neutral_symbol = 'R_SPF_NEUTRAL',
+
+  dkim_allow_symbol = 'R_DKIM_ALLOW',
+  dkim_deny_symbol = 'R_DKIM_REJECT',
+}
+-- Default port for redis upstreams
+local default_port = 6379
+local upstreams = nil
+local dmarc_redis_key_prefix = "dmarc_"
+
+local elts_re = rspamd_regexp.create_cached(";\\s+")
+
+local function dmarc_report(task, spf_ok, dkim_ok)
+  local ip = task:get_from_ip()
+  if not ip:is_valid() then
+    return nil
+  end
+  local res = string.format('%d:%s:%s:%s', task:get_date(0),
+    ip:to_string(), tostring(spf_ok), tostring(dkim_ok))
+    
+  return res
+end
+
+local function dmarc_callback(task)
+  local from = task:get_from()
+  
+  local function dmarc_report_cb(task, err, data)
+    if not err then
+      rspamd_logger.info(string.format('<%s> dmarc report saved for %s',
+        task:get_message_id(), from[1]['domain']))
+    else
+      rspamd_logger.err(string.format('<%s> dmarc report is not saved for %s: %s',
+        task:get_message_id(), from[1]['domain'], err))
+    end
+  end
+  
+  local function dmarc_dns_cb(resolver, to_resolve, results, err, key)
+    local strict_spf = false
+    local strict_dkim = false
+    local strict_policy = false
+    local rua
+    
+    if results then
+      for _,r in ipairs(results) do
+        local elts = elts_re:split(r)
+
+        if elts then
+          for _,e in ipairs(elts) do
+            dkim_pol = string.match(e, '^adkim=([sr])$')
+            if dkim_pol and dkim_pol == 's' then
+              strict_dkim = true
+            end
+            spf_pol = string.match(e, '^aspf=([sr])$')
+            if spf_pol and spf_pol == 's' then
+              strict_spf = true
+            end
+            policy = string.match(e, '^p=reject$')
+            if policy then
+              strict_policy = true
+            end
+            
+            if not rua then
+              rua = string.match(e, '^rua=([^%s]+)$')
+            end
+          end
+        end
+      end
+    end
+
+    if strict_spf then
+      -- Handle subdomains
+    end
+    if strict_dkim then
+      -- Handle subdomain
+    end
+    
+    -- Check dkim and spf symbols
+    local spf_ok = false
+    local dkim_ok = false
+    if task:get_symbol(symbols['spf_allow_symbol']) then spf_ok = true end
+    if task:get_symbol(symbols['dkim_allow_symbol']) then dkim_ok = true end
+    
+    if strict_policy and (not spf_ok or not dkim_ok) then
+      local res = 0.5
+      if not dkim_ok and not spf_ok then res = 1.0 end
+      
+      task:insert_result('DMARC_STRICT_DENY', res)
+      
+    elseif strict_policy then
+      task:insert_result('DMARC_STRICT_ALLOW', res)
+    end
+    
+    if rua and (not spf_ok or not dkim_ok) and upstreams then
+      -- Prepare and send redis report element
+      local upstream = upstreams:get_upstream_by_hash(from[1]['domain'])
+      local redis_key = dmarc_redis_key_prefix .. from[1]['domain']
+      local addr = upstream:get_addr()
+      local report_data = dmarc_report(task, spf_ok, dkim_ok)
+      
+      if report_data then
+        rspamd_redis.make_request(task, addr, dmarc_report_cb, 
+          'LPUSH', {redis_key, report_data})
+      end
+    end
+    
+    -- XXX: handle rua and push data to redis
+  end
+  
+  if from and from[1]['domain'] then
+    -- XXX: use tld list here and generate top level domain
+    local dmarc_domain = '_dmarc.' .. from[1]['domain']
+    task:get_resolver():resolve_txt(task:get_session(), task:get_mempool(),
+      dmarc_domain, dmarc_dns_cb)
+  end
+end
+
+local opts = rspamd_config:get_all_opt('dmarc')
+if not opts or type(opts) ~= 'table' then
+  return
+end
+
+if not opts['servers'] then
+  rspamd_logger.err('no servers are specified for dmarc stats')
+else
+  upstreams = upstream_list.create(opts['servers'], default_port)
+  if not upstreams then
+    rspamd_logger.err('cannot parse servers parameter')
+  end
+end
+
+if opts['key_prefix'] then
+  dmarc_redis_key_prefix = opts['key_prefix']
+end
+
+-- Check spf and dkim sections for changed symbols
+local function check_mopt(var, opts, name)
+  if opts[name] then
+    symbols['var'] = tostring(opts[name])
+  end
+end
+
+local spf_opts = rspamd_config:get_all_opt('spf')
+if spf_opts then
+  check_mopt('spf_deny_symbol', spf_opts, 'symbol_fail')
+  check_mopt('spf_allow_symbol', spf_opts, 'symbol_allow')
+  check_mopt('spf_softfail_symbol', spf_opts, 'symbol_softfail')
+  check_mopt('spf_neutral_symbol', spf_opts, 'symbol_neutral')
+end
+
+local dkim_opts = rspamd_config:get_all_opt('dkim')
+if dkim_opts then
+  check_mopt('dkim_deny_symbol', 'symbol_reject')
+  check_mopt('dkim_allow_symbol', 'symbol_allow')
+end
+
+rspamd_config:register_virtual_symbol('DMARC_POLICY_ALLOW', -1)
+rspamd_config:register_virtual_symbol('DMARC_POLICY_REJECT', 1)
+rspamd_config:register_post_filter(dmarc_callback)