text: # -*- coding: iso-8859-1 -*-
  #
  # Copyright (c) 2002, 2003, 2005, 2006 Allan Saddi <allan@saddi.com>
  # All rights reserved.
  #
  # This software is licensed as described in the file COPYING, which
  # you should have received as part of this distribution. The terms
  # are also available at http://trac.edgewall.org/wiki/TracLicense.
  #
  # This software consists of voluntary contributions made by many
  # individuals. For the exact contribution history, see the revision
  # history and logs, available at http://trac.edgewall.org/log/.
  #
  # Author: Allan Saddi <allan@saddi.com>
  
  """
  fcgi - a FastCGI/WSGI gateway.
  
  For more information about FastCGI, see <http://www.fastcgi.com/>.
  
  For more information about the Web Server Gateway Interface, see
  
  <http://www.python.org/peps/pep-0333.html>.
  
  Example usage:
  
    #!/usr/bin/env python
    from myapplication import app # Assume app is your WSGI application object
    from fcgi import WSGIServer
    WSGIServer(app).run()
  
  See the documentation for WSGIServer/Server for more information.
  
  On most platforms, fcgi will fallback to regular CGI behavior if run in a
  non-FastCGI context. If you want to force CGI behavior, set the environment
  variable FCGI_FORCE_CGI to "Y" or "y".
  """
  
  __author__ = 'Allan Saddi <allan@saddi.com>'
  __version__ = '$Revision: 2025 $'
  
  import io
  import sys
  import os
  import signal
  import struct
  import select
  import socket
  import errno
  import traceback
  
  try:
      import thread
      import threading
      thread_available = True
  except ImportError:
      import dummy_thread as thread
      import dummy_threading as threading
      thread_available = False
  
  # Apparently 2.3 doesn't define SHUT_WR? Assume it is 1 in this case.
  if not hasattr(socket, 'SHUT_WR'):
      socket.SHUT_WR = 1
  
  __all__ = ['WSGIServer']
  
  # Constants from the spec.
  FCGI_LISTENSOCK_FILENO = 0
  
  FCGI_HEADER_LEN = 8
  
  FCGI_VERSION_1 = 1
  
  FCGI_BEGIN_REQUEST = 1
  FCGI_ABORT_REQUEST = 2
  FCGI_END_REQUEST = 3
  FCGI_PARAMS = 4
  FCGI_STDIN = 5
  FCGI_STDOUT = 6
  FCGI_STDERR = 7
  FCGI_DATA = 8
  FCGI_GET_VALUES = 9
  FCGI_GET_VALUES_RESULT = 10
  FCGI_UNKNOWN_TYPE = 11
  FCGI_MAXTYPE = FCGI_UNKNOWN_TYPE
  
  FCGI_NULL_REQUEST_ID = 0
  
  FCGI_KEEP_CONN = 1
  
  FCGI_RESPONDER = 1
  FCGI_AUTHORIZER = 2
  FCGI_FILTER = 3
  
  FCGI_REQUEST_COMPLETE = 0
  FCGI_CANT_MPX_CONN = 1
  FCGI_OVERLOADED = 2
  FCGI_UNKNOWN_ROLE = 3
  
  FCGI_MAX_CONNS = 'FCGI_MAX_CONNS'
  FCGI_MAX_REQS = 'FCGI_MAX_REQS'
  FCGI_MPXS_CONNS = 'FCGI_MPXS_CONNS'
  
  FCGI_Header = '!BBHHBx'
  FCGI_BeginRequestBody = '!HB5x'
  FCGI_EndRequestBody = '!LB3x'
  FCGI_UnknownTypeBody = '!B7x'
  
  FCGI_EndRequestBody_LEN = struct.calcsize(FCGI_EndRequestBody)
  FCGI_UnknownTypeBody_LEN = struct.calcsize(FCGI_UnknownTypeBody)
  
  if __debug__:
      import time
  
      # Set non-zero to write debug output to a file.
      DEBUG = 0
      DEBUGLOG = '/tmp/fcgi.log'
  
      def _debug(level, msg):
          if DEBUG < level:
              return
  
          try:
              with open(DEBUGLOG, 'a') as f:
                  f.write('%sfcgi: %s\n' % (time.ctime()[4:-4], msg))
          except:
              pass
  
  class InputStream(object):
      """
      File-like object representing FastCGI input streams (FCGI_STDIN and
      FCGI_DATA). Supports the minimum methods required by WSGI spec.
      """
      def __init__(self, conn):
          self._conn = conn
  
          # See Server.
          self._shrinkThreshold = conn.server.inputStreamShrinkThreshold
  
          self._buf = ''
          self._bufList = []
          self._pos = 0 # Current read position.
          self._avail = 0 # Number of bytes currently available.
  
          self._eof = False # True when server has sent EOF notification.
  
      def _shrinkBuffer(self):
          """Gets rid of already read data (since we can't rewind)."""
          if self._pos >= self._shrinkThreshold:
              self._buf = self._buf[self._pos:]
              self._avail -= self._pos
              self._pos = 0
  
              assert self._avail >= 0
  
      def _waitForData(self):
          """Waits for more data to become available."""
          self._conn.process_input()
  
      def read(self, n=-1):
          if self._pos == self._avail and self._eof:
              return ''
          while True:
              if n < 0 or (self._avail - self._pos) < n:
                  # Not enough data available.
                  if self._eof:
                      # And there's no more coming.
                      newPos = self._avail
                      break
                  else:
                      # Wait for more data.
                      self._waitForData()
                      continue
              else:
                  newPos = self._pos + n
                  break
          # Merge buffer list, if necessary.
          if self._bufList:
              self._buf += ''.join(self._bufList)
              self._bufList = []
          r = self._buf[self._pos:newPos]
          self._pos = newPos
          self._shrinkBuffer()
          return r
  
      def readline(self, length=None):
          if self._pos == self._avail and self._eof:
              return ''
          while True:
              # Unfortunately, we need to merge the buffer list early.
              if self._bufList:
                  self._buf += ''.join(self._bufList)
                  self._bufList = []
              # Find newline.
              i = self._buf.find('\n', self._pos)
              if i < 0:
                  # Not found?
                  if self._eof:
                      # No more data coming.
                      newPos = self._avail
                      break
                  else:
                      # Wait for more to come.
                      self._waitForData()
                      continue
              else:
                  newPos = i + 1
                  break
          if length is not None:
              if self._pos + length < newPos:
                  newPos = self._pos + length
          r = self._buf[self._pos:newPos]
          self._pos = newPos
          self._shrinkBuffer()
          return r
  
      def readlines(self, sizehint=0):
          total = 0
          lines = []
          line = self.readline()
          while line:
              lines.append(line)
              total += len(line)
              if 0 < sizehint <= total:
                  break
              line = self.readline()
          return lines
  
      def __iter__(self):
          return self
  
      def __next__(self):
          r = self.readline()
          if not r:
              raise StopIteration
          return r
  
      next = __next__
  
      def add_data(self, data):
          if not data:
              self._eof = True
          else:
              self._bufList.append(data)
              self._avail += len(data)
  
  class MultiplexedInputStream(InputStream):
      """
      A version of InputStream meant to be used with MultiplexedConnections.
      Assumes the MultiplexedConnection (the producer) and the Request
      (the consumer) are running in different threads.
      """
      def __init__(self, conn):
          super(MultiplexedInputStream, self).__init__(conn)
  
          # Arbitrates access to this InputStream (it's used simultaneously
          # by a Request and its owning Connection object).
          lock = threading.RLock()
  
          # Notifies Request thread that there is new data available.
          self._lock = threading.Condition(lock)
  
      def _waitForData(self):
          # Wait for notification from add_data().
          self._lock.wait()
  
      def read(self, n=-1):
          self._lock.acquire()
          try:
              return super(MultiplexedInputStream, self).read(n)
          finally:
              self._lock.release()
  
      def readline(self, length=None):
          self._lock.acquire()
          try:
              return super(MultiplexedInputStream, self).readline(length)
          finally:
              self._lock.release()
  
      def add_data(self, data):
          self._lock.acquire()
          try:
              super(MultiplexedInputStream, self).add_data(data)
              self._lock.notify()
          finally:
              self._lock.release()
  
  class OutputStream(object):
      """
      FastCGI output stream (FCGI_STDOUT/FCGI_STDERR). By default, calls to
      write() or writelines() immediately result in Records being sent back
      to the server. Buffering should be done in a higher level!
      """
      def __init__(self, conn, req, type, buffered=False):
          self._conn = conn
          self._req = req
          self._type = type
          self._buffered = buffered
          self._bufList = [] # Used if buffered is True
          self.dataWritten = False
          self.closed = False
  
      def _write(self, data):
          length = len(data)
          while length:
              toWrite = min(length, self._req.server.maxwrite - FCGI_HEADER_LEN)
  
              rec = Record(self._type, self._req.requestId)
              rec.contentLength = toWrite
              rec.contentData = data[:toWrite]
              self._conn.writeRecord(rec)
  
              data = data[toWrite:]
              length -= toWrite
  
      def write(self, data):
          assert not self.closed
  
          if not data:
              return
  
          self.dataWritten = True
  
          if self._buffered:
              self._bufList.append(data)
          else:
              self._write(data)
  
      def writelines(self, lines):
          assert not self.closed
  
          for line in lines:
              self.write(line)
  
      def flush(self):
          # Only need to flush if this OutputStream is actually buffered.
          if self._buffered:
              data = ''.join(self._bufList)
              self._bufList = []
              self._write(data)
  
      # Though available, the following should NOT be called by WSGI apps.
      def close(self):
          """Sends end-of-stream notification, if necessary."""
          if not self.closed and self.dataWritten:
              self.flush()
              rec = Record(self._type, self._req.requestId)
              self._conn.writeRecord(rec)
              self.closed = True
  
  class TeeOutputStream(object):
      """
      Simple wrapper around two or more output file-like objects that copies
      written data to all streams.
      """
      def __init__(self, streamList):
          self._streamList = streamList
  
      def write(self, data):
          for f in self._streamList:
              f.write(data)
  
      def writelines(self, lines):
          for line in lines:
              self.write(line)
  
      def flush(self):
          for f in self._streamList:
              f.flush()
  
  class StdoutWrapper(object):
      """
      Wrapper for sys.stdout so we know if data has actually been written.
      """
      def __init__(self, stdout):
          self._file = stdout
          self.dataWritten = False
  
      def write(self, data):
          if data:
              self.dataWritten = True
          self._file.write(data)
  
      def writelines(self, lines):
          for line in lines:
              self.write(line)
  
      def __getattr__(self, name):
          return getattr(self._file, name)
  
  def decode_pair(s, pos=0):
      """
      Decodes a name/value pair.
  
      The number of bytes decoded as well as the name/value pair
      are returned.
      """
      nameLength = ord(s[pos])
      if nameLength & 128:
          nameLength = struct.unpack('!L', s[pos:pos+4])[0] & 0x7fffffff
          pos += 4
      else:
          pos += 1
  
      valueLength = ord(s[pos])
      if valueLength & 128:
          valueLength = struct.unpack('!L', s[pos:pos+4])[0] & 0x7fffffff
          pos += 4
      else:
          pos += 1
  
      name = s[pos:pos+nameLength]
      pos += nameLength
      value = s[pos:pos+valueLength]
      pos += valueLength
  
      return pos, (name, value)
  
  def encode_pair(name, value):
      """
      Encodes a name/value pair.
  
      The encoded string is returned.
      """
      nameLength = len(name)
      if nameLength < 128:
          s = chr(nameLength)
      else:
          s = struct.pack('!L', nameLength | 0x80000000L)
  
      valueLength = len(value)
      if valueLength < 128:
          s += chr(valueLength)
      else:
          s += struct.pack('!L', valueLength | 0x80000000L)
  
      return s + name + value
  
  class Record(object):
      """
      A FastCGI Record.
  
      Used for encoding/decoding records.
      """
      def __init__(self, type=FCGI_UNKNOWN_TYPE, requestId=FCGI_NULL_REQUEST_ID):
          self.version = FCGI_VERSION_1
          self.type = type
          self.requestId = requestId
          self.contentLength = 0
          self.paddingLength = 0
          self.contentData = ''
  
      @staticmethod
      def _recvall(sock, length):
          """
          Attempts to receive length bytes from a socket, blocking if necessary.
          (Socket may be blocking or non-blocking.)
          """
          dataList = []
          recvLen = 0
          while length:
              try:
                  data = sock.recv(length)
              except socket.error as e:
                  if e[0] == errno.EAGAIN:
                      select.select([sock], [], [])
                      continue
                  else:
                      raise
              if not data: # EOF
                  break
              dataList.append(data)
              dataLen = len(data)
              recvLen += dataLen
              length -= dataLen
          return ''.join(dataList), recvLen
  
      def read(self, sock):
          """Read and decode a Record from a socket."""
          try:
              header, length = self._recvall(sock, FCGI_HEADER_LEN)
          except:
              raise EOFError
  
          if length < FCGI_HEADER_LEN:
              raise EOFError
  
          self.version, self.type, self.requestId, self.contentLength, \
                        self.paddingLength = struct.unpack(FCGI_Header, header)
  
          if __debug__: _debug(9, 'read: fd = %d, type = %d, requestId = %d, '
                               'contentLength = %d' %
                               (sock.fileno(), self.type, self.requestId,
                                self.contentLength))
  
          if self.contentLength:
              try:
                  self.contentData, length = self._recvall(sock,
                                                           self.contentLength)
              except:
                  raise EOFError
  
              if length < self.contentLength:
                  raise EOFError
  
          if self.paddingLength:
              try:
                  self._recvall(sock, self.paddingLength)
              except:
                  raise EOFError
  
      @staticmethod
      def _sendall(sock, data):
          """
          Writes data to a socket and does not return until all the data is sent.
          """
          length = len(data)
          while length:
              try:
                  sent = sock.send(data)
              except socket.error as e:
                  if e[0] == errno.EAGAIN:
                      select.select([], [sock], [])
                      continue
                  else:
                      raise
              data = data[sent:]
              length -= sent
  
      def write(self, sock):
          """Encode and write a Record to a socket."""
          self.paddingLength = -self.contentLength & 7
  
          if __debug__: _debug(9, 'write: fd = %d, type = %d, requestId = %d, '
                               'contentLength = %d' %
                               (sock.fileno(), self.type, self.requestId,
                                self.contentLength))
  
          header = struct.pack(FCGI_Header, self.version, self.type,
                               self.requestId, self.contentLength,
                               self.paddingLength)
          self._sendall(sock, header)
          if self.contentLength:
              self._sendall(sock, self.contentData)
          if self.paddingLength:
              self._sendall(sock, '\x00'*self.paddingLength)
  
  class Request(object):
      """
      Represents a single FastCGI request.
  
      These objects are passed to your handler and is the main interface
      between your handler and the fcgi module. The methods should not
      be called by your handler. However, server, params, stdin, stdout,
      stderr, and data are free for your handler's use.
      """
      def __init__(self, conn, inputStreamClass):
          self._conn = conn
  
          self.server = conn.server
          self.params = {}
          self.stdin = inputStreamClass(conn)
          self.stdout = OutputStream(conn, self, FCGI_STDOUT)
          self.stderr = OutputStream(conn, self, FCGI_STDERR, buffered=True)
          self.data = inputStreamClass(conn)
  
      def run(self):
          """Runs the handler, flushes the streams, and ends the request."""
          try:
              protocolStatus, appStatus = self.server.handler(self)
          except:
              traceback.print_exc(file=self.stderr)
              self.stderr.flush()
              if not self.stdout.dataWritten:
                  self.server.error(self)
  
              protocolStatus, appStatus = FCGI_REQUEST_COMPLETE, 0
  
          if __debug__: _debug(1, 'protocolStatus = %d, appStatus = %d' %
                               (protocolStatus, appStatus))
  
          try:
              self._flush()
              self._end(appStatus, protocolStatus)
          except socket.error as e:
              if e[0] != errno.EPIPE:
                  raise
  
      def _end(self, appStatus=0L, protocolStatus=FCGI_REQUEST_COMPLETE):
          self._conn.end_request(self, appStatus, protocolStatus)
  
      def _flush(self):
          self.stdout.close()
          self.stderr.close()
  
  class CGIRequest(Request):
      """A normal CGI request disguised as a FastCGI request."""
      def __init__(self, server):
          # These are normally filled in by Connection.
          self.requestId = 1
          self.role = FCGI_RESPONDER
          self.flags = 0
          self.aborted = False
  
          self.server = server
          self.params = dict(os.environ)
          self.stdin = sys.stdin
          self.stdout = StdoutWrapper(sys.stdout) # Oh, the humanity!
          self.stderr = sys.stderr
          self.data = io.BytesIO()
  
      def _end(self, appStatus=0L, protocolStatus=FCGI_REQUEST_COMPLETE):
          sys.exit(appStatus)
  
      def _flush(self):
          # Not buffered, do nothing.
          pass
  
  class Connection(object):
      """
      A Connection with the web server.
  
      Each Connection is associated with a single socket (which is
      connected to the web server) and is responsible for handling all
      the FastCGI message processing for that socket.
      """
      _multiplexed = False
      _inputStreamClass = InputStream
  
      def __init__(self, sock, addr, server):
          self._sock = sock
          self._addr = addr
          self.server = server
  
          # Active Requests for this Connection, mapped by request ID.
          self._requests = {}
  
      def _cleanupSocket(self):
          """Close the Connection's socket."""
          try:
              self._sock.shutdown(socket.SHUT_WR)
          except:
              return
          try:
              while True:
                  r, w, e = select.select([self._sock], [], [])
                  if not r or not self._sock.recv(1024):
                      break
          except:
              pass
          self._sock.close()
  
      def run(self):
          """Begin processing data from the socket."""
          self._keepGoing = True
          while self._keepGoing:
              try:
                  self.process_input()
              except EOFError:
                  break
              except (select.error, socket.error) as e:
                  if e[0] == errno.EBADF: # Socket was closed by Request.
                      break
                  raise
  
          self._cleanupSocket()
  
      def process_input(self):
          """Attempt to read a single Record from the socket and process it."""
          # Currently, any children Request threads notify this Connection
          # that it is no longer needed by closing the Connection's socket.
          # We need to put a timeout on select, otherwise we might get
          # stuck in it indefinitely... (I don't like this solution.)
          while self._keepGoing:
              try:
                  r, w, e = select.select([self._sock], [], [], 1.0)
              except ValueError:
                  # Sigh. ValueError gets thrown sometimes when passing select
                  # a closed socket.
                  raise EOFError
              if r: break
          if not self._keepGoing:
              return
          rec = Record()
          rec.read(self._sock)
  
          if rec.type == FCGI_GET_VALUES:
              self._do_get_values(rec)
          elif rec.type == FCGI_BEGIN_REQUEST:
              self._do_begin_request(rec)
          elif rec.type == FCGI_ABORT_REQUEST:
              self._do_abort_request(rec)
          elif rec.type == FCGI_PARAMS:
              self._do_params(rec)
          elif rec.type == FCGI_STDIN:
              self._do_stdin(rec)
          elif rec.type == FCGI_DATA:
              self._do_data(rec)
          elif rec.requestId == FCGI_NULL_REQUEST_ID:
              self._do_unknown_type(rec)
          else:
              # Need to complain about this.
              pass
  
      def writeRecord(self, rec):
          """
          Write a Record to the socket.
          """
          rec.write(self._sock)
  
      def end_request(self, req, appStatus=0L,
                      protocolStatus=FCGI_REQUEST_COMPLETE, remove=True):
          """
          End a Request.
  
          Called by Request objects. An FCGI_END_REQUEST Record is
          sent to the web server. If the web server no longer requires
          the connection, the socket is closed, thereby ending this
          Connection (run() returns).
          """
          rec = Record(FCGI_END_REQUEST, req.requestId)
          rec.contentData = struct.pack(FCGI_EndRequestBody, appStatus,
                                        protocolStatus)
          rec.contentLength = FCGI_EndRequestBody_LEN
          self.writeRecord(rec)
  
          if remove:
              del self._requests[req.requestId]
  
          if __debug__: _debug(2, 'end_request: flags = %d' % req.flags)
  
          if not (req.flags & FCGI_KEEP_CONN) and not self._requests:
              self._cleanupSocket()
              self._keepGoing = False
  
      def _do_get_values(self, inrec):
          """Handle an FCGI_GET_VALUES request from the web server."""
          outrec = Record(FCGI_GET_VALUES_RESULT)
  
          pos = 0
          while pos < inrec.contentLength:
              pos, (name, value) = decode_pair(inrec.contentData, pos)
              cap = self.server.capability.get(name)
              if cap is not None:
                  outrec.contentData += encode_pair(name, str(cap))
  
          outrec.contentLength = len(outrec.contentData)
          self.writeRecord(outrec)
  
      def _do_begin_request(self, inrec):
          """Handle an FCGI_BEGIN_REQUEST from the web server."""
          role, flags = struct.unpack(FCGI_BeginRequestBody, inrec.contentData)
  
          req = self.server.request_class(self, self._inputStreamClass)
          req.requestId, req.role, req.flags = inrec.requestId, role, flags
          req.aborted = False
  
          if not self._multiplexed and self._requests:
              # Can't multiplex requests.
              self.end_request(req, 0L, FCGI_CANT_MPX_CONN, remove=False)
          else:
              self._requests[inrec.requestId] = req
  
      def _do_abort_request(self, inrec):
          """
          Handle an FCGI_ABORT_REQUEST from the web server.
  
          We just mark a flag in the associated Request.
          """
          req = self._requests.get(inrec.requestId)
          if req is not None:
              req.aborted = True
  
      def _start_request(self, req):
          """Run the request."""
          # Not multiplexed, so run it inline.
          req.run()
  
      def _do_params(self, inrec):
          """
          Handle an FCGI_PARAMS Record.
  
          If the last FCGI_PARAMS Record is received, start the request.
          """
          req = self._requests.get(inrec.requestId)
          if req is not None:
              if inrec.contentLength:
                  pos = 0
                  while pos < inrec.contentLength:
                      pos, (name, value) = decode_pair(inrec.contentData, pos)
                      req.params[name] = value
              else:
                  self._start_request(req)
  
      def _do_stdin(self, inrec):
          """Handle the FCGI_STDIN stream."""
          req = self._requests.get(inrec.requestId)
          if req is not None:
              req.stdin.add_data(inrec.contentData)
  
      def _do_data(self, inrec):
          """Handle the FCGI_DATA stream."""
          req = self._requests.get(inrec.requestId)
          if req is not None:
              req.data.add_data(inrec.contentData)
  
      def _do_unknown_type(self, inrec):
          """Handle an unknown request type. Respond accordingly."""
          outrec = Record(FCGI_UNKNOWN_TYPE)
          outrec.contentData = struct.pack(FCGI_UnknownTypeBody, inrec.type)
          outrec.contentLength = FCGI_UnknownTypeBody_LEN
          self.writeRecord(outrec)
  
  class MultiplexedConnection(Connection):
      """
      A version of Connection capable of handling multiple requests
      simultaneously.
      """
      _multiplexed = True
      _inputStreamClass = MultiplexedInputStream
  
      def __init__(self, sock, addr, server):
          super(MultiplexedConnection, self).__init__(sock, addr, server)
  
          # Used to arbitrate access to self._requests.
          lock = threading.RLock()
  
          # Notification is posted everytime a request completes, allowing us
          # to quit cleanly.
          self._lock = threading.Condition(lock)
  
      def _cleanupSocket(self):
          # Wait for any outstanding requests before closing the socket.
          self._lock.acquire()
          while self._requests:
              self._lock.wait()
          self._lock.release()
  
          super(MultiplexedConnection, self)._cleanupSocket()
  
      def writeRecord(self, rec):
          # Must use locking to prevent intermingling of Records from different
          # threads.
          self._lock.acquire()
          try:
              # Probably faster than calling super. ;)
              rec.write(self._sock)
          finally:
              self._lock.release()
  
      def end_request(self, req, appStatus=0L,
                      protocolStatus=FCGI_REQUEST_COMPLETE, remove=True):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self).end_request(req, appStatus,
                                                             protocolStatus,
                                                             remove)
              self._lock.notify()
          finally:
              self._lock.release()
  
      def _do_begin_request(self, inrec):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self)._do_begin_request(inrec)
          finally:
              self._lock.release()
  
      def _do_abort_request(self, inrec):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self)._do_abort_request(inrec)
          finally:
              self._lock.release()
  
      def _start_request(self, req):
          thread.start_new_thread(req.run, ())
  
      def _do_params(self, inrec):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self)._do_params(inrec)
          finally:
              self._lock.release()
  
      def _do_stdin(self, inrec):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self)._do_stdin(inrec)
          finally:
              self._lock.release()
  
      def _do_data(self, inrec):
          self._lock.acquire()
          try:
              super(MultiplexedConnection, self)._do_data(inrec)
          finally:
              self._lock.release()
  
  class Server(object):
      """
      The FastCGI server.
  
      Waits for connections from the web server, processing each
      request.
  
      If run in a normal CGI context, it will instead instantiate a
      CGIRequest and run the handler through there.
      """
      request_class = Request
      cgirequest_class = CGIRequest
  
      # Limits the size of the InputStream's string buffer to this size + the
      # server's maximum Record size. Since the InputStream is not seekable,
      # we throw away already-read data once this certain amount has been read.
      inputStreamShrinkThreshold = 102400 - 8192
  
      def __init__(self, handler=None, maxwrite=8192, bindAddress=None,
                   umask=None, multiplexed=False):
          """
          handler, if present, must reference a function or method that
          takes one argument: a Request object. If handler is not
          specified at creation time, Server *must* be subclassed.
          (The handler method below is abstract.)
  
          maxwrite is the maximum number of bytes (per Record) to write
          to the server. I've noticed mod_fastcgi has a relatively small
          receive buffer (8K or so).
  
          bindAddress, if present, must either be a string or a 2-tuple. If
          present, run() will open its own listening socket. You would use
          this if you wanted to run your application as an 'external' FastCGI
          app. (i.e. the webserver would no longer be responsible for starting
          your app) If a string, it will be interpreted as a filename and a UNIX
          socket will be opened. If a tuple, the first element, a string,
          is the interface name/IP to bind to, and the second element (an int)
          is the port number.
  
          Set multiplexed to True if you want to handle multiple requests
          per connection. Some FastCGI backends (namely mod_fastcgi) don't
          multiplex requests at all, so by default this is off (which saves
          on thread creation/locking overhead). If threads aren't available,
          this keyword is ignored; it's not possible to multiplex requests
          at all.
          """
          if handler is not None:
              self.handler = handler
          self.maxwrite = maxwrite
          if thread_available:
              try:
                  import resource
                  # Attempt to glean the maximum number of connections
                  # from the OS.
                  maxConns = resource.getrlimit(resource.RLIMIT_NOFILE)[0]
              except (ImportError, AttributeError):
                  maxConns = 100 # Just some made up number.
              maxReqs = maxConns
              if multiplexed:
                  self._connectionClass = MultiplexedConnection
                  maxReqs *= 5 # Another made up number.
              else:
                  self._connectionClass = Connection
              self.capability = {
                  FCGI_MAX_CONNS: maxConns,
                  FCGI_MAX_REQS: maxReqs,
                  FCGI_MPXS_CONNS: multiplexed and 1 or 0
                  }
          else:
              self._connectionClass = Connection
              self.capability = {
                  # If threads aren't available, these are pretty much correct.
                  FCGI_MAX_CONNS: 1,
                  FCGI_MAX_REQS: 1,
                  FCGI_MPXS_CONNS: 0
                  }
          self._bindAddress = bindAddress
          self._umask = umask
  
      def _setupSocket(self):
          if self._bindAddress is None: # Run as a normal FastCGI?
              isFCGI = True
  
              sock = socket.fromfd(FCGI_LISTENSOCK_FILENO, socket.AF_INET,
                                   socket.SOCK_STREAM)
              try:
                  sock.getpeername()
              except socket.error as e:
                  if e[0] == errno.ENOTSOCK:
                      # Not a socket, assume CGI context.
                      isFCGI = False
                  elif e[0] != errno.ENOTCONN:
                      raise
  
              # FastCGI/CGI discrimination is broken on Mac OS X.
              # Set the environment variable FCGI_FORCE_CGI to "Y" or "y"
              # if you want to run your app as a simple CGI. (You can do
              # this with Apache's mod_env [not loaded by default in OS X
              # client, ha ha] and the SetEnv directive.)
              if not isFCGI or \
                 os.environ.get('FCGI_FORCE_CGI', 'N').upper().startswith('Y'):
                  req = self.cgirequest_class(self)
                  req.run()
                  sys.exit(0)
          else:
              # Run as a server
              oldUmask = None
              if type(self._bindAddress) is str:
                  # Unix socket
                  sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
                  try:
                      os.unlink(self._bindAddress)
                  except OSError:
                      pass
                  if self._umask is not None:
                      oldUmask = os.umask(self._umask)
              else:
                  # INET socket
                  assert type(self._bindAddress) is tuple
                  assert len(self._bindAddress) == 2
                  sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                  sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
  
              sock.bind(self._bindAddress)
              sock.listen(socket.SOMAXCONN)
  
              if oldUmask is not None:
                  os.umask(oldUmask)
  
          return sock
  
      def _cleanupSocket(self, sock):
          """Closes the main socket."""
          sock.close()
  
      def _installSignalHandlers(self):
          self._oldSIGs = [(x,signal.getsignal(x)) for x in
                           (signal.SIGHUP, signal.SIGINT, signal.SIGTERM)]
          signal.signal(signal.SIGHUP, self._hupHandler)
          signal.signal(signal.SIGINT, self._intHandler)
          signal.signal(signal.SIGTERM, self._intHandler)
  
      def _restoreSignalHandlers(self):
          for signum,handler in self._oldSIGs:
              signal.signal(signum, handler)
  
      def _hupHandler(self, signum, frame):
          self._hupReceived = True
          self._keepGoing = False
  
      def _intHandler(self, signum, frame):
          self._keepGoing = False
  
      def run(self, timeout=1.0):
          """
          The main loop. Exits on SIGHUP, SIGINT, SIGTERM. Returns True if
          SIGHUP was received, False otherwise.
          """
          web_server_addrs = os.environ.get('FCGI_WEB_SERVER_ADDRS')
          if web_server_addrs is not None:
              web_server_addrs = map(lambda x: x.strip(),
                                     web_server_addrs.split(','))
  
          sock = self._setupSocket()
  
          self._keepGoing = True
          self._hupReceived = False
  
          # Install signal handlers.
          self._installSignalHandlers()
  
          while self._keepGoing:
              try:
                  r, w, e = select.select([sock], [], [], timeout)
              except select.error as e:
                  if e[0] == errno.EINTR:
                      continue
                  raise
  
              if r:
                  try:
                      clientSock, addr = sock.accept()
                  except socket.error as e:
                      if e[0] in (errno.EINTR, errno.EAGAIN):
                          continue
                      raise
  
                  if web_server_addrs and \
                         (len(addr) != 2 or addr[0] not in web_server_addrs):
                      clientSock.close()
                      continue
  
                  # Instantiate a new Connection and begin processing FastCGI
                  # messages (either in a new thread or this thread).
                  conn = self._connectionClass(clientSock, addr, self)
                  thread.start_new_thread(conn.run, ())
  
              self._mainloopPeriodic()
  
          # Restore signal handlers.
          self._restoreSignalHandlers()
  
          self._cleanupSocket(sock)
  
          return self._hupReceived
  
      def _mainloopPeriodic(self):
          """
          Called with just about each iteration of the main loop. Meant to
          be overridden.
          """
          pass
  
      def _exit(self, reload=False):
          """
          Protected convenience method for subclasses to force an exit. Not
          really thread-safe, which is why it isn't public.
          """
          if self._keepGoing:
              self._keepGoing = False
              self._hupReceived = reload
  
      def handler(self, req):
          """
          Default handler, which just raises an exception. Unless a handler
          is passed at initialization time, this must be implemented by
          a subclass.
          """
          raise NotImplementedError(self.__class__.__name__ + '.handler')
  
      def error(self, req):
          """
          Called by Request if an exception occurs within the handler. May and
          should be overridden.
          """
          import cgitb
          req.stdout.write('Content-Type: text/html\r\n\r\n' +
                           cgitb.html(sys.exc_info()))
  
  class WSGIServer(Server):
      """
      FastCGI server that supports the Web Server Gateway Interface. See
      <http://www.python.org/peps/pep-0333.html>.
      """
      def __init__(self, application, environ=None,
                   multithreaded=True, **kw):
          """
          environ, if present, must be a dictionary-like object. Its
          contents will be copied into application's environ. Useful
          for passing application-specific variables.
  
          Set multithreaded to False if your application is not MT-safe.
          """
          if 'handler' in kw:
              del kw['handler'] # Doesn't make sense to let this through
          super(WSGIServer, self).__init__(**kw)
  
          if environ is None:
              environ = {}
  
          self.application = application
          self.environ = environ
          self.multithreaded = multithreaded
  
          # Used to force single-threadedness
          self._app_lock = thread.allocate_lock()
  
      def handler(self, req):
          """Special handler for WSGI."""
          if req.role != FCGI_RESPONDER:
              return FCGI_UNKNOWN_ROLE, 0
  
          # Mostly taken from example CGI gateway.
          environ = req.params
          environ.update(self.environ)
  
          environ['wsgi.version'] = (1,0)
          environ['wsgi.input'] = req.stdin
          if self._bindAddress is None:
              stderr = req.stderr
          else:
              stderr = TeeOutputStream((sys.stderr, req.stderr))
          environ['wsgi.errors'] = stderr
          environ['wsgi.multithread'] = not isinstance(req, CGIRequest) and \
                                        thread_available and self.multithreaded
          # Rationale for the following: If started by the web server
          # (self._bindAddress is None) in either FastCGI or CGI mode, the
          # possibility of being spawned multiple times simultaneously is quite
          # real. And, if started as an external server, multiple copies may be
          # spawned for load-balancing/redundancy. (Though I don't think
          # mod_fastcgi supports this?)
          environ['wsgi.multiprocess'] = True
          environ['wsgi.run_once'] = isinstance(req, CGIRequest)
  
          if environ.get('HTTPS', '').lower() in ('yes', 'on', '1'):
              environ['wsgi.url_scheme'] = 'https'
          elif environ.get('HTTP_X_FORWARDED_PROTO', '').lower() == 'https':
              environ['wsgi.url_scheme'] = 'https'
          else:
              environ['wsgi.url_scheme'] = 'http'
  
          self._sanitizeEnv(environ)
  
          headers_set = []
          headers_sent = []
          result = None
  
          def write(data):
              assert type(data) is str, 'write() argument must be string'
              assert headers_set, 'write() before start_response()'
  
              if not headers_sent:
                  status, responseHeaders = headers_sent[:] = headers_set
                  found = False
                  for header,value in responseHeaders:
                      if header.lower() == 'content-length':
                          found = True
                          break
                  if not found and result is not None:
                      try:
                          if len(result) == 1:
                              responseHeaders.append(('Content-Length',
                                                      str(len(data))))
                      except:
                          pass
                  s = 'Status: %s\r\n' % status
                  for header in responseHeaders:
                      s += '%s: %s\r\n' % header
                  s += '\r\n'
                  req.stdout.write(s)
  
              req.stdout.write(data)
              req.stdout.flush()
  
          def start_response(status, response_headers, exc_info=None):
              if exc_info:
                  try:
                      if headers_sent:
                          # Re-raise if too late
                          raise exc_info[0], exc_info[1], exc_info[2]
                  finally:
                      exc_info = None # avoid dangling circular ref
              else:
                  assert not headers_set, 'Headers already set!'
  
              assert type(status) is str, 'Status must be a string'
              assert len(status) >= 4, 'Status must be at least 4 characters'
              assert int(status[:3]), 'Status must begin with 3-digit code'
              assert status[3] == ' ', 'Status must have a space after code'
              assert type(response_headers) is list, 'Headers must be a list'
              if __debug__:
                  for name,val in response_headers:
                      assert type(name) is str, 'Header names must be strings'
                      assert type(val) is str, 'Header values must be strings'
  
              headers_set[:] = [status, response_headers]
              return write
  
          if not self.multithreaded:
              self._app_lock.acquire()
          try:
              try:
                  result = self.application(environ, start_response)
                  try:
                      for data in result:
                          if data:
                              write(data)
                      if not headers_sent:
                          write('') # in case body was empty
                  finally:
                      if hasattr(result, 'close'):
                          result.close()
              except socket.error as e:
                  if e[0] != errno.EPIPE:
                      raise # Don't let EPIPE propagate beyond server
          finally:
              if not self.multithreaded:
                  self._app_lock.release()
  
          return FCGI_REQUEST_COMPLETE, 0
  
      def _sanitizeEnv(self, environ):
          """Ensure certain values are present, if required by WSGI."""
          if 'SCRIPT_NAME' not in environ:
              environ['SCRIPT_NAME'] = ''
          if 'PATH_INFO' not in environ:
              environ['PATH_INFO'] = ''
  
          # If any of these are missing, it probably signifies a broken
          # server...
          for name,default in [('REQUEST_METHOD', 'GET'),
                               ('SERVER_NAME', 'localhost'),
                               ('SERVER_PORT', '80'),
                               ('SERVER_PROTOCOL', 'HTTP/1.0')]:
              if name not in environ:
                  environ['wsgi.errors'].write('%s: missing FastCGI param %s '
                                               'required by WSGI!\n' %
                                               (self.__class__.__name__, name))
                  environ[name] = default
  
  if __name__ == '__main__':
      def test_app(environ, start_response):
          """Probably not the most efficient example."""
          import cgi
          start_response('200 OK', [('Content-Type', 'text/html')])
          yield '<html><head><title>Hello World!</title></head>\n' \
                '<body>\n' \
                '<p>Hello World!</p>\n' \
                '<table border="1">'
          for name in sorted(environ):
              yield '<tr><td>%s</td><td>%s</td></tr>\n' % (
                  name, cgi.escape(environ[name]))
  
          form = cgi.FieldStorage(fp=environ['wsgi.input'], environ=environ,
                                  keep_blank_values=1)
          if form.list:
              yield '<tr><th colspan="2">Form data</th></tr>'
  
          for field in form.list:
              yield '<tr><td>%s</td><td>%s</td></tr>\n' % (
                  field.name, field.value)
  
          yield '</table>\n' \
                '</body></html>\n'
  
      WSGIServer(test_app).run()
  