From: Minero Aoki <aamine@...>
Date: 2000-07-25T18:12:30+09:00
Subject: [ruby-list:24012] Re: SMTP server (mail filter proxy)

あおきです。

  In mail "[ruby-list:24009] SMTP server (mail filter proxy)"
    Hideto ISHIBASHI <hideto-i@rr.iij4u.or.jp> wrote:

> こんにちは。石橋"rubyholic"秀仁です。
> 
> いまメールフィルタを作ろうとしています。
> 情報・御意見をお願いします。

> Ruby の MTA があれば、一番かんたんですよね。

この前ちょこっと書いたのがあるんで、よければ使ってください。
ただし 7 月中は一切の改善要求に応えられませんのであしからず。
-------------------------------------------------------------------
あおきみねろう

#
# smtpd.rb
#

require 'socket'


class SMTPd

  def initialize( port )
    @port = port
  end

  def execute
    if $DEBUG then
      waitcall
    end

    fork do
      Process.setsid
      fork do
        $stdin.close
        $stdout.close
        $stderr.close
        waitcall
      end

      exit!
    end
    exit!
  end


  private

  def waitcall
    s = TCPServer.open( @port )

    trap( 'SIGINT' ) { exit! }
    trap( 'SIGHUP' ) { exit! }
    trap( 'SIGTERM' ) { exit! }

    while true do
      @sock = s.accept
      begin
        session
      ensure
        @sock.close
      end
    end
  end

  def session
    from = nil
    to = {}
    @rbuf = ''

    writeline "220 #{Socket.gethostname} ESMTP"
    while true do
      case resp = readline
      when /\A(?:helo|ehlo)/i
        writeline '250 ok'

      when /\Amail from:<(\S+)>/i
        from = $1
        to.clear
        writeline '250 ok'

      when /\Arcpt to:<(\S+)>/i
        unless from then
          writeline '508 MAIL first'
          next
        end

        to[$1] = true
        writeline '250 ok'

      when /\Adata/i
        unless from then
          writeline '508 MAIL first'
          next
        end
        if to.empty? then
          writeline '508 RCPT first'
          next
        end

        writeline '354 go ahead'
        recvmail from, to
        writeline '250 ok'
        from = nil
        to.clear

      when /\Aquit/i
        writeline "221 #{Socket.gethostname}"
        to = from = nil
        @rbuf = ''
        break

      else
        writeline '502 unimplemented'
      end
    end
  end

  def recvmail( from, to )
    tmp = nil

    # とりあえずはファイルに書いてるだけ

    File.open( 'tmp', 'w' ) do |f|
      f.puts "smtp from=#{from}"
      to.each_key do |i|
        f.puts "smtp to=#{i}"
      end
      f.puts

      # 本体
      while true do
        tmp = readline
        tmp.sub! /\A\../, '.'
        break if tmp == '.'

        f.write tmp, "\r\n"
      end
    end
  end

  def writeline( msg )
    @sock.write msg + "\r\n"
    @sock.flush
  end

  def readline
    until m = /\r\n/.match( @rbuf ) do
# p @rbuf
      @rbuf << @sock.sysread( 1024 )
      if @rbuf.size > 1024 * 3 then
        writeline '508 line too long'
        @rbuf.clear
      end
    end
# p @rbuf
    @rbuf = m.post_match
    m.pre_match
  end

end


if $0 == __FILE__ then
  $DEBUG = true
  puts 'debug mode. try "telnet localhost 12525" from other terminal'
  smtp = SMTPd.new( 12525 )
  smtp.execute
end