实现qmail下邮件过滤和邮件到达短信通知

本邮件系统在freebsd 4.10上实施成功。
1、对于邮件系统的安装，没有太多说的。建议大家看HD的http://bsd.huangdong.com/server/mail/qmail.html来安装。如果已经安装了有qmail+vpopmail+qmail_queue补丁的，请直接跳到4继续安装。在新装邮件服务器时有几点需要注意的是，安装qmail的时候应该将步骤改为：
cd /usr/ports/mail/qmail
make WITH_QMAILQUEUE_PATCH=yes WITH_BIG_TODO_PATCH=yes WITH_OUTGOINGIP_PATCH=yes WITH_PRESERVE_CONFIG_FILES=yes extract
cd /usr/ports/mail/qmail/work/qmail-1.03
fetch http://www.nimh.org/dl/qmail-smtpd.c
cd /usr/ports/mail/qmail
make WITH_QMAILQUEUE_PATCH=yes WITH_BIG_TODO_PATCH=yes WITH_OUTGOINGIP_PATCH=yes WITH_PRESERVE_CONFIG_FILES=yes install
make disable-sendmail
make enable-qmail
make clean

在安装vpopmail的时候可能因为port更新的原因让使用vpopmail的时候出现奇怪问题，最好是安装webmin将建立的vpopmail数据库删除后，重新建立，并指定数据库的用户权限。由于webmin的安装不是本文重点，这里将忽略。

2、关于文章里面的杀毒部分因为系统效率问题，我没有安装。各位请自行决定是否安装。

3、反垃圾邮件当然需要，我用的是http://anti-spam.org.cn的cbl+服务。使用的时候只需要将smtpd的脚本改为：
#!/bin/sh
QMAILDUID=`/usr/bin/id -u qmaild`
NOFILESGID=`/usr/bin/id -g qmaild`
exec /usr/local/bin/tcpserver -H -R -l 0 -p -x \
        /usr/local/vpopmail/etc/tcp.smtp.cdb -u"$QMAILDUID" \
        -g"$NOFILESGID" -v -c100 0 smtp rblsmtpd \
        -r cblplus.anti-spam.org.cn \
        -r relays.ordb.org \
        /var/qmail/bin/qmail-smtpd /usr/local/vpopmail/bin/vchkpw-smtpd /usr/bin/true 2>&1

从http://anti-spam.org.cn/cgi-bin/rblclient/（你的邮件服务器的dns服务器IP地址)看到你的邮件服务器的流量和使用cbl+服务的情况。

4、这里是重点了。过滤和短信到达是需要qmail_queue来完成的，一定要打这个包。

使用python来实现这个功能，当然需要安装python啦。
cd /usr/ports/lang/python
make;make install;make clean
一般来讲这个安装是非常顺利的。
安装结束后。
cd /var/qmail/bin
编辑qmfilt.py，内容如下：

#!/usr/local/bin/python --

import os, sys, string, time, traceback, re, socket

Version  = '1.1'
PyVersion  = '1.0'
Logging  = 1
Debug    = 0
QmailD   = 82#这里需要和你/etc/password里面qmaild用户的一样
LogFile  = None
TestMode = None
Filters  = []
MailEnvelope = ''
MailData     = ''
ValidActions = { 'trap': '', 'drop' : '', 'block' :'' }

#这里是你通过ucp协议将消息发送到哪个服务器的哪个端口
def mail_sms(msg):
    host = "xxx.xxx.114.2"
    port = 9999
    buf = 500
    addr = (host,port)

    # Create socket
    UDPSock = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)

    def_msg = msg;
    UDPSock.sendto(def_msg,addr)

    # Close socket
    UDPSock.close()

def openlog():
  global LogFile

  if not Logging:
     return
  try:
    LogFile = os.open('/var/log/qmfilt', os.O_APPEND|os.O_WRONLY|os.O_CREAT, 0744)
  except:
    if TestMode:
      print "Can't create /var/log/qmfilt"
    else:
      # Indicate a write error
      sys.exit(53)

def log(message):
  message = time.asctime(time.localtime(time.time())) + " - " + message + "\n"
  if Logging:
    os.write(LogFile, message)
    # Indicate a write error
    #sys.exit(53)
  if TestMode:
    print message

def showFilters():
 
  if len(Filters) == 0:
    print "No filters"
  for f in Filters:
    print "Filter -  %s - Action: %s  Regex: %s" % (f[0], f[1], f[2])

def readFilters():
  global Filters

  try:
    file = open('/var/qmail/control/qmfilt', 'r')
    configLines = file.readlines()
    file.close()
  except:
    log("Can't read /var/qmail/control/qmfilt")
    if not TestMode:
      # Indicate a 'cannot read config file error'
      sys.exit(53)

  reg = re.compile('(.*)::(.+)::(.+)::')
  for line in configLines:
    if line[0] == '#':
      continue
    m = reg.match(line)
    if m != None:
      action = string.lower(m.group(2))
      if not ValidActions.has_key(action):
         log("Invalid action in config file [%s] - SKIPPED" %(action))
         continue
      Filters.append( [m.group(1), string.lower(m.group(2)), m.group(3)] )
   
def readDescriptor(desc):
  result = ''
  while 1:
    data = os.read(desc, 16384)
    if data == '':
      break
    result = result + data

  return result

def writeDescriptor(desc, data):
  while data:
    num  = os.write(desc, data)
    data = data[num:]

  os.close(desc)

def filterHits():
 
  for regEx in Filters:
    reg = re.compile(regEx[2], re.M|re.I)
    match = reg.search(MailData)
    if match:
      log("Matched [%s]" % (regEx[0]))
      return regEx[1], regEx[0]

  return None,None

def storeInTrap(hit):
  try:
    pid = os.getpid()
    mailFile = os.open('/var/qmail/qmfilt/qmfilt.%s' %(pid), os.O_WRONLY|os.O_CREAT|os.O_EXCL, 0744)
  except:
    log("Can't create /var/qmail/qmfilt/qmfilt.%s" %(pid))
    # Indicate a write error
    sys.exit(53)

  try:
    #如果不屏蔽会出现很多问题，至于为什么我还没弄明白，如果你找到问题所在，请告诉我。
    """(None, inode, None, None, None, None, size, None, None, None) = os.fstat(mailFile)"""
    os.rename('/var/qmail/qmfilt/qmfilt.%s' %(pid), '/var/qmail/qmfilt/%s.mail' %(inode))
  except:
    log("Can't rename /var/qmail/qmfilt/qmfilt.%s -> /var/qmail/qmfilt/%s.mail" %(pid, inode))
    # Indicate a write error
    sys.exit(53)

  try:
    envFile = os.open('/var/qmail/qmfilt/%s.envelope' %(inode), os.O_WRONLY|os.O_CREAT|os.O_EXCL, 0744)
    mesgFile = os.open('/var/qmail/qmfilt/%s.qmfilt' %(inode), os.O_WRONLY|os.O_CREAT|os.O_EXCL, 0744)
    writeDescriptor(mailFile, MailData)
    writeDescriptor(envFile,  MailEnvelope)
    writeDescriptor(mesgFile, "Matched filter [ %s] to file %s" %(hit, inode))
    log("Matched filter [ %s] to file %s" %(hit, inode))
  except:
    log("Can't create/write files into trap")
    # Indicate a write error
    sys.exit(53)

  return 0

def sendToQmailQueue():
 
  # Open a pipe to qmail queue
  fd0 = os.pipe()
  fd1 = os.pipe()
  pid = os.fork()
  if pid < 0:
    log("Error couldn't fork")
    sys.exit(81)
  if pid == 0:
    # This is the child
    os.dup2(fd0[0], 0)
    os.dup2(fd1[0], 1)
    i = 2
    while (i < 64):
      try:
        os.close(i)
      except:
        pass
      i = i + 1
    os.chdir('/var/qmail')
    #time.sleep(10)
    os.execv("bin/qmail-queue", ('bin/qmail-queue',))
    log("Something went wrong")
    sys.exit(127)  # This is only reached on error
  else:
    # This is the parent
    # close the readable descriptors
    os.close(fd0[0])
    os.close(fd1[0])

  # Send the data
  recvHdr = "Received: (QMFILT: %s); " %(Version)
  recvHdr = recvHdr + time.strftime("%d %b %Y %H:%M:%S", time.gmtime(time.time()))
  recvHdr = recvHdr + " -0000\n"
  os.write(fd0[1], recvHdr)
  writeDescriptor(fd0[1], MailData)
  writeDescriptor(fd1[1], MailEnvelope)

  # Catch the exit code to return
  result = os.waitpid(pid, 0)[1]
  if PyVersion > '1.5.1':
    if os.WIFEXITED(result):
      return os.WEXITSTATUS(result)
    else:
      log("Didn't exit normally")
      sys.exit(81)
  else:
    return result

def conver(msg):
  msg = msg.replace(chr(00),' ')
  msg = msg.replace('F','From:',1)
  msg = msg.replace(' T',' To:')
  return msg
   

def main(argv, stdout, environ):

  global TestMode
  global MailData
  global MailEnvelope
  global PyVersion

  PyVersion = string.split(sys.version)[0]

  if len(argv) > 1 and argv[1] == '--test':
    TestMode = 1

  os.setuid(QmailD)

  # Insure Environment is OK

  # Try to open log
  openlog()

  if not os.path.exists('/var/qmail/qmfilt'):
    # Indicate a problem with the queue directory
    log("Directory /var/qmail/qmfilt doesn't exist")
    if not TestMode:
      sys.exit(61)

  if os.path.exists('/var/qmail/control/qmfilt'):
    readFilters()
  else:
    if TestMode:
      print "No filter file /var/qmail/control/qmfilt - no filters applied"

  if TestMode:
    showFilters()

  # Go no further if in test mode
  if TestMode:
    sys.exit(0)

 

  # Get the data

  # Read the data
  MailData     = readDescriptor(0)

  # Read the envelope
  MailEnvelope = readDescriptor(1)
  if Debug:
    log(MailData)
    log(MailEnvelope)

  action,hit = filterHits()

  if action == 'trap':
    storeInTrap(hit)
  if action == 'block':
    log("Matched filter [ %s] and email was BLOCKED/Refused delivery" %(hit))
    sys.exit(31)
  if action == 'drop':
    log("Matched filter [ %s] and email was DROPPED" %(hit))
  if action == None:
    sendToQmailQueue()
  #Log
  log(conver(MailEnvelope))
  #send sms
  mail_sms(conver(MailEnvelope))

  if Debug:
    log("qmailqueue returned [%d]" %(result))
  sys.exit(0)

if __name__ == "__main__":
  try:
    main(sys.argv, sys.stdout, os.environ)

  # Catch the sys.exit() errors
  except SystemExit, val:
    sys.exit(val)
  except:
    # return a fatal error for the unknown error
    if TestMode:
      traceback.print_exc()
    sys.exit(81)

然后在cd /var/qmail/control
编辑qmfilt内容如下：
#
# This is the qmfilt control file
# If any email comes in that matches this
# filter, the mail will be redirected
# to the filter directory
#
# A filter regular expression must be on a single
# line and in between a pair of '::'
#
# Valid actions:
# trap - store in the trap directory
# block - tell the smtp sender that we won't take the mail
# drop - accept the mail, but don't queue it
#

# This will match any executable Visual Basic Scripts
VisualBasic::block::^Content-Type: application/octet-stream;\s+name="(.*\.vbs)"::
SHS::block::^Content-Type: application/octet-stream;\s+name="(.*\.shs)"::
SHB::block::^Content-Type: application/octet-stream;\s+name="(.*\.shb)"::
COM::block::^Content-Type: application/octet-stream;\s+name="(.*\.com)"::
EXE::block::^Content-Type: application/octet-stream;\s+name="(.*\.exe)"::
SCR::block::^Content-Type: application/octet-stream;\s+name="(.*\.scr)"::
PIF::block::^Content-Type: application/octet-stream;\s+name="(.*\.pif)"::
BAT::block::^Content-Type: application/octet-stream;\s+name="(.*\.bat)"::

# This is the Outlook date overflow bug
DATE::block::^Date:.{160,}::

在/var/log下建立qmfilt文件，内容为空
chown qmaild qmfilt
在/var/qmail下建立qmfilt目录。
chown -R qmaild qmfilt
好了，来让我们的程序启用吧
先测试一把
/var/qmail/bin/qmfilt.py --test
如果返回了先定义的qmfilt里面的内容，恭喜成功了一半了。内容应该和下面的相似：
Filter - VisualBasic - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.vbs)"
Filter - SHS - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.shs)"
Filter - SHB - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.shb)"
Filter - COM - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.com)"
Filter - EXE - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.exe)"
Filter - SCR - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.scr)"
Filter - PIF - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.pif)"
Filter - BAT - Action: block Regex: ^Content-Type: application/octet-stream;\s+name="(.*\.bat)"
Filter - DATE - Action: block Regex: ^Date:.{160,}
好了，让我们的过滤器用起来吧
cd /usr/local/vpopmail/etc
编译tcp.smtp内容如下
127.:allow,RELAYCLIENT="",QMAILQUEUE="bin/qmfilt.py"
:allow,QMAILQUEUE="bin/qmfilt.py"
然后生成tcp.smtp.cdb文件
tcprules tcp.smtp.cdb tcp.smtp.tmp < tcp.smtp
，发个带exe为附件的邮件看看。如果成功过滤，应该在/var/log/qmfilt里面看到如下信息：
Fri Sep 10 14:37:01 2004 - Matched filter [ EXE] and email was BLOCKED/Refused delivery
Fri Sep 10 14:38:09 2004 - Matched [SCR]
如果你是用foxmail等客户端发送带exe为结尾的邮件的话，服务器会提示你拒绝接收的。
到这里，你的邮件过滤已经成功了。
你可以在/var/qmail/control的qmfilt文件里面定义你需要过滤的指定代码，然后测试规则是否生效了。

关于短信到达通知，因为安全和商业上的问题。不能将服务器端的代码贴出来。我将机制给大家讲一下。
qmfilt.py这个程序里面mail_sms用udp将类似From:info@xxx.com.cn To:weilx@xxx.com发送到指定的服务器上。服务器接收到这个数据包后，将这个数据包的内容用短信发送出去。
当然可以将邮件主题等信息一起发送到手机上，大家根据自己的情况更改吧。

这个程序是根据http://sourceforge.net/projects/qmfilt/这个项目更改的，但是直接用他的代码会造成不能收信，大家可以在这个项目的cvs关注他的代码修改情况。