[Feature] Add lua_smtp library

diff --git a/lualib/lua_smtp.lua b/lualib/lua_smtp.lua
new file mode 100644 (file)
index 0000000..1b15249
--- /dev/null
+++ b/lualib/lua_smtp.lua
@@ -0,0 +1,195 @@
+--[[
+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 rspamd_tcp = require "rspamd_tcp"
+
+local exports = {}
+
+local CRLF = '\r\n'
+
+--[[[
+-- @function lua_smtp.sendmail(task, message, opts, callback)
+--]]
+local function sendmail(task, message, opts, callback)
+  local stage = 'connect'
+
+  local function mail_cb(err, data, conn)
+    local function no_error_write(merr)
+      if merr then
+        callback(false, string.format('error on stage %s: %s',
+            stage, merr))
+        if conn then
+          conn:close()
+        end
+
+        return false
+      end
+
+      return true
+    end
+
+    local function no_error_read(merr, mdata, wantcode)
+      wantcode = wantcode or '2'
+      if merr then
+        callback(false, string.format('error on stage %s: %s',
+          stage, merr))
+        if conn then
+          conn:close()
+        end
+
+        return false
+      end
+      if mdata then
+        if type(mdata) ~= 'string' then
+          mdata = tostring(mdata)
+        end
+        if string.sub(mdata, 1, 1) ~= wantcode then
+          callback(false, string.format('bad smtp responce on stage %s: "%s" when "%s" expected',
+              stage, mdata, wantcode))
+          if conn then
+            conn:close()
+          end
+          return false
+        end
+      else
+        callback(false, string.format('no data on stage %s',
+            stage))
+        if conn then
+          conn:close()
+        end
+        return false
+      end
+      return true
+    end
+
+    -- After quit
+    local function all_done_cb(merr, mdata)
+      if conn then
+        conn:close()
+      end
+
+      callback(true, nil)
+
+      return true
+    end
+
+    -- QUIT stage
+    local function quit_done_cb(_, _)
+      conn:add_read(all_done_cb, CRLF)
+    end
+    local function quit_cb(merr, mdata)
+      if no_error_read(merr, mdata) then
+        conn:add_write(quit_done_cb, 'QUIT' .. CRLF)
+      end
+    end
+    local function pre_quit_cb(merr, _)
+      if no_error_write(merr) then
+        stage = 'quit'
+        conn:add_read(quit_cb, CRLF)
+      end
+    end
+
+    -- DATA stage
+    local function data_done_cb(merr, mdata)
+      if no_error_read(merr, mdata, '3') then
+        conn:add_write(pre_quit_cb, {message, CRLF.. '.' .. CRLF})
+      end
+    end
+    local function data_cb(merr, _)
+      if no_error_write(merr) then
+        conn:add_read(data_done_cb, CRLF)
+      end
+    end
+
+    -- RCPT phase
+    local next_recipient
+    local function rcpt_done_cb_gen(i)
+      return function (merr, mdata)
+        if no_error_read(merr, mdata) then
+          if i == #opts.recipients then
+            conn:add_write(data_cb, 'DATA' .. CRLF)
+          else
+            next_recipient(i + 1)
+          end
+        end
+      end
+    end
+
+    local function rcpt_cb_gen(i)
+      return function (merr, _)
+        if no_error_write(merr, '2') then
+          conn:add_read(rcpt_done_cb_gen(i), CRLF)
+        end
+      end
+    end
+
+    next_recipient = function(i)
+      conn:add_write(rcpt_cb_gen(i),
+          string.format('RCPT TO: <%s>%s', opts.recipients[i], CRLF))
+    end
+
+    -- FROM stage
+    local function from_done_cb(merr, mdata)
+      -- We need to iterate over recipients sequentially
+      if no_error_read(merr, mdata, '2') then
+        stage = 'rcpt'
+        next_recipient(1)
+      end
+    end
+    local function from_cb(merr, _)
+      if no_error_write(merr) then
+        conn:add_read(from_done_cb, CRLF)
+      end
+    end
+    local function hello_done_cb(merr, mdata)
+      if no_error_read(merr, mdata) then
+        stage = 'from'
+        conn:add_write(from_cb, string.format(
+            'MAIL FROM: <%s>%s', opts.from, CRLF))
+      end
+    end
+
+    -- HELLO stage
+    local function hello_cb(merr)
+      if no_error_write(merr) then
+        conn:add_read(hello_done_cb, CRLF)
+      end
+    end
+    if no_error_read(err, data) then
+      stage = 'helo'
+      conn:add_write(hello_cb, string.format('HELO %s%s',
+        opts.helo, CRLF))
+    end
+  end
+
+  if type(opts.recipients) == 'string' then
+    opts.recipients = {opts.recipients}
+  end
+
+  if not rspamd_tcp.request({
+    task = task,
+    callback = mail_cb,
+    stop_pattern = CRLF,
+    host = opts.host,
+    port = opts.port or 25,
+  }) then
+    callback(false, 'cannot make a TCP connection')
+  end
+end
+
+exports.sendmail = sendmail
+
+return exports
\ No newline at end of file