text: """IMAP4 client.
  
  Based on RFC 2060.
  
  Public class:           IMAP4
  Public variable:        Debug
  Public functions:       Internaldate2tuple
                          Int2AP
                          ParseFlags
                          Time2Internaldate
  """
  
  # Author: Piers Lauder <piers@cs.su.oz.au> December 1997.
  #
  # Authentication code contributed by Donn Cave <donn@u.washington.edu> June 1998.
  # String method conversion by ESR, February 2001.
  # GET/SETACL contributed by Anthony Baxter <anthony@interlink.com.au> April 2001.
  # IMAP4_SSL contributed by Tino Lange <Tino.Lange@isg.de> March 2002.
  # GET/SETQUOTA contributed by Andreas Zeidler <az@kreativkombinat.de> June 2002.
  # PROXYAUTH contributed by Rick Holbert <holbert.13@osu.edu> November 2002.
  # GET/SETANNOTATION contributed by Tomas Lindroos <skitta@abo.fi> June 2005.
  
  __version__ = "2.58"
  
  import binascii, errno, random, re, socket, subprocess, sys, time, calendar
  from io import DEFAULT_BUFFER_SIZE
  
  try:
      import ssl
      HAVE_SSL = True
  except ImportError:
      HAVE_SSL = False
  
  __all__ = ["IMAP4", "IMAP4_stream", "Internaldate2tuple",
             "Int2AP", "ParseFlags", "Time2Internaldate"]
  
  #       Globals
  
  CRLF = b'\r\n'
  Debug = 0
  IMAP4_PORT = 143
  IMAP4_SSL_PORT = 993
  AllowedVersions = ('IMAP4REV1', 'IMAP4')        # Most recent first
  
  # Maximal line length when calling readline(). This is to prevent
  # reading arbitrary length lines. RFC 3501 and 2060 (IMAP 4rev1)
  # don't specify a line length. RFC 2683 however suggests limiting client
  # command lines to 1000 octets and server command lines to 8000 octets.
  # We have selected 10000 for some extra margin and since that is supposedly
  # also what UW and Panda IMAP does.
  _MAXLINE = 10000
  
  
  #       Commands
  
  Commands = {
          # name            valid states
          'APPEND':       ('AUTH', 'SELECTED'),
          'AUTHENTICATE': ('NONAUTH',),
          'CAPABILITY':   ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
          'CHECK':        ('SELECTED',),
          'CLOSE':        ('SELECTED',),
          'COPY':         ('SELECTED',),
          'CREATE':       ('AUTH', 'SELECTED'),
          'DELETE':       ('AUTH', 'SELECTED'),
          'DELETEACL':    ('AUTH', 'SELECTED'),
          'EXAMINE':      ('AUTH', 'SELECTED'),
          'EXPUNGE':      ('SELECTED',),
          'FETCH':        ('SELECTED',),
          'GETACL':       ('AUTH', 'SELECTED'),
          'GETANNOTATION':('AUTH', 'SELECTED'),
          'GETQUOTA':     ('AUTH', 'SELECTED'),
          'GETQUOTAROOT': ('AUTH', 'SELECTED'),
          'MYRIGHTS':     ('AUTH', 'SELECTED'),
          'LIST':         ('AUTH', 'SELECTED'),
          'LOGIN':        ('NONAUTH',),
          'LOGOUT':       ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
          'LSUB':         ('AUTH', 'SELECTED'),
          'NAMESPACE':    ('AUTH', 'SELECTED'),
          'NOOP':         ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
          'PARTIAL':      ('SELECTED',),                                  # NB: obsolete
          'PROXYAUTH':    ('AUTH',),
          'RENAME':       ('AUTH', 'SELECTED'),
          'SEARCH':       ('SELECTED',),
          'SELECT':       ('AUTH', 'SELECTED'),
          'SETACL':       ('AUTH', 'SELECTED'),
          'SETANNOTATION':('AUTH', 'SELECTED'),
          'SETQUOTA':     ('AUTH', 'SELECTED'),
          'SORT':         ('SELECTED',),
          'STARTTLS':     ('NONAUTH',),
          'STATUS':       ('AUTH', 'SELECTED'),
          'STORE':        ('SELECTED',),
          'SUBSCRIBE':    ('AUTH', 'SELECTED'),
          'THREAD':       ('SELECTED',),
          'UID':          ('SELECTED',),
          'UNSUBSCRIBE':  ('AUTH', 'SELECTED'),
          }
  
  #       Patterns to match server responses
  
  Continuation = re.compile(br'\+( (?P<data>.*))?')
  Flags = re.compile(br'.*FLAGS \((?P<flags>[^\)]*)\)')
  InternalDate = re.compile(br'.*INTERNALDATE "'
          br'(?P<day>[ 0123][0-9])-(?P<mon>[A-Z][a-z][a-z])-(?P<year>[0-9][0-9][0-9][0-9])'
          br' (?P<hour>[0-9][0-9]):(?P<min>[0-9][0-9]):(?P<sec>[0-9][0-9])'
          br' (?P<zonen>[-+])(?P<zoneh>[0-9][0-9])(?P<zonem>[0-9][0-9])'
          br'"')
  Literal = re.compile(br'.*{(?P<size>\d+)}$', re.ASCII)
  MapCRLF = re.compile(br'\r\n|\r|\n')
  Response_code = re.compile(br'\[(?P<type>[A-Z-]+)( (?P<data>[^\]]*))?\]')
  Untagged_response = re.compile(br'\* (?P<type>[A-Z-]+)( (?P<data>.*))?')
  Untagged_status = re.compile(
      br'\* (?P<data>\d+) (?P<type>[A-Z-]+)( (?P<data2>.*))?', re.ASCII)
  
  
  
  class IMAP4:
  
      """IMAP4 client class.
  
      Instantiate with: IMAP4([host[, port]])
  
              host - host's name (default: localhost);
              port - port number (default: standard IMAP4 port).
  
      All IMAP4rev1 commands are supported by methods of the same
      name (in lower-case).
  
      All arguments to commands are converted to strings, except for
      AUTHENTICATE, and the last argument to APPEND which is passed as
      an IMAP4 literal.  If necessary (the string contains any
      non-printing characters or white-space and isn't enclosed with
      either parentheses or double quotes) each string is quoted.
      However, the 'password' argument to the LOGIN command is always
      quoted.  If you want to avoid having an argument string quoted
      (eg: the 'flags' argument to STORE) then enclose the string in
      parentheses (eg: "(\Deleted)").
  
      Each command returns a tuple: (type, [data, ...]) where 'type'
      is usually 'OK' or 'NO', and 'data' is either the text from the
      tagged response, or untagged results from command. Each 'data'
      is either a string, or a tuple. If a tuple, then the first part
      is the header of the response, and the second part contains
      the data (ie: 'literal' value).
  
      Errors raise the exception class <instance>.error("<reason>").
      IMAP4 server errors raise <instance>.abort("<reason>"),
      which is a sub-class of 'error'. Mailbox status changes
      from READ-WRITE to READ-ONLY raise the exception class
      <instance>.readonly("<reason>"), which is a sub-class of 'abort'.
  
      "error" exceptions imply a program error.
      "abort" exceptions imply the connection should be reset, and
              the command re-tried.
      "readonly" exceptions imply the command should be re-tried.
  
      Note: to use this module, you must read the RFCs pertaining to the
      IMAP4 protocol, as the semantics of the arguments to each IMAP4
      command are left to the invoker, not to mention the results. Also,
      most IMAP servers implement a sub-set of the commands available here.
      """
  
      class error(Exception): pass    # Logical errors - debug required
      class abort(error): pass        # Service errors - close and retry
      class readonly(abort): pass     # Mailbox status changed to READ-ONLY
  
      def __init__(self, host = '', port = IMAP4_PORT):
          self.debug = Debug
          self.state = 'LOGOUT'
          self.literal = None             # A literal argument to a command
          self.tagged_commands = {}       # Tagged commands awaiting response
          self.untagged_responses = {}    # {typ: [data, ...], ...}
          self.continuation_response = '' # Last continuation response
          self.is_readonly = False        # READ-ONLY desired state
          self.tagnum = 0
          self._tls_established = False
  
          # Open socket to server.
  
          self.open(host, port)
  
          try:
              self._connect()
          except Exception:
              try:
                  self.shutdown()
              except socket.error:
                  pass
              raise
  
  
      def _connect(self):
          # Create unique tag for this session,
          # and compile tagged response matcher.
  
          self.tagpre = Int2AP(random.randint(4096, 65535))
          self.tagre = re.compile(br'(?P<tag>'
                          + self.tagpre
                          + br'\d+) (?P<type>[A-Z]+) (?P<data>.*)', re.ASCII)
  
          # Get server welcome message,
          # request and store CAPABILITY response.
  
          if __debug__:
              self._cmd_log_len = 10
              self._cmd_log_idx = 0
              self._cmd_log = {}           # Last `_cmd_log_len' interactions
              if self.debug >= 1:
                  self._mesg('imaplib version %s' % __version__)
                  self._mesg('new IMAP4 connection, tag=%s' % self.tagpre)
  
          self.welcome = self._get_response()
          if 'PREAUTH' in self.untagged_responses:
              self.state = 'AUTH'
          elif 'OK' in self.untagged_responses:
              self.state = 'NONAUTH'
          else:
              raise self.error(self.welcome)
  
          self._get_capabilities()
          if __debug__:
              if self.debug >= 3:
                  self._mesg('CAPABILITIES: %r' % (self.capabilities,))
  
          for version in AllowedVersions:
              if not version in self.capabilities:
                  continue
              self.PROTOCOL_VERSION = version
              return
  
          raise self.error('server not IMAP4 compliant')
  
  
      def __getattr__(self, attr):
          #       Allow UPPERCASE variants of IMAP4 command methods.
          if attr in Commands:
              return getattr(self, attr.lower())
          raise AttributeError("Unknown IMAP4 command: '%s'" % attr)
  
  
  
      #       Overridable methods
  
  
      def _create_socket(self):
          return socket.create_connection((self.host, self.port))
  
      def open(self, host = '', port = IMAP4_PORT):
          """Setup connection to remote server on "host:port"
              (default: localhost:standard IMAP4 port).
          This connection will be used by the routines:
              read, readline, send, shutdown.
          """
          self.host = host
          self.port = port
          self.sock = self._create_socket()
          self.file = self.sock.makefile('rb')
  
  
      def read(self, size):
          """Read 'size' bytes from remote."""
          chunks = []
          read = 0
          while read < size:
              data = self.file.read(min(size-read, 4096))
              if not data:
                  break
              read += len(data)
              chunks.append(data)
          return b''.join(chunks)
  
  
      def readline(self):
          """Read line from remote."""
          line = self.file.readline(_MAXLINE + 1)
          if len(line) > _MAXLINE:
              raise self.error("got more than %d bytes" % _MAXLINE)
          return line
  
  
      def send(self, data):
          """Send data to remote."""
          self.sock.sendall(data)
  
  
      def shutdown(self):
          """Close I/O established in "open"."""
          self.file.close()
          try:
              self.sock.shutdown(socket.SHUT_RDWR)
          except socket.error as e:
              # The server might already have closed the connection
              if e.errno != errno.ENOTCONN:
                  raise
          finally:
              self.sock.close()
  
  
      def socket(self):
          """Return socket instance used to connect to IMAP4 server.
  
          socket = <instance>.socket()
          """
          return self.sock
  
  
  
      #       Utility methods
  
  
      def recent(self):
          """Return most recent 'RECENT' responses if any exist,
          else prompt server for an update using the 'NOOP' command.
  
          (typ, [data]) = <instance>.recent()
  
          'data' is None if no new messages,
          else list of RECENT responses, most recent last.
          """
          name = 'RECENT'
          typ, dat = self._untagged_response('OK', [None], name)
          if dat[-1]:
              return typ, dat
          typ, dat = self.noop()  # Prod server for response
          return self._untagged_response(typ, dat, name)
  
  
      def response(self, code):
          """Return data for response 'code' if received, or None.
  
          Old value for response 'code' is cleared.
  
          (code, [data]) = <instance>.response(code)
          """
          return self._untagged_response(code, [None], code.upper())
  
  
  
      #       IMAP4 commands
  
  
      def append(self, mailbox, flags, date_time, message):
          """Append message to named mailbox.
  
          (typ, [data]) = <instance>.append(mailbox, flags, date_time, message)
  
                  All args except `message' can be None.
          """
          name = 'APPEND'
          if not mailbox:
              mailbox = 'INBOX'
          if flags:
              if (flags[0],flags[-1]) != ('(',')'):
                  flags = '(%s)' % flags
          else:
              flags = None
          if date_time:
              date_time = Time2Internaldate(date_time)
          else:
              date_time = None
          self.literal = MapCRLF.sub(CRLF, message)
          return self._simple_command(name, mailbox, flags, date_time)
  
  
      def authenticate(self, mechanism, authobject):
          """Authenticate command - requires response processing.
  
          'mechanism' specifies which authentication mechanism is to
          be used - it must appear in <instance>.capabilities in the
          form AUTH=<mechanism>.
  
          'authobject' must be a callable object:
  
                  data = authobject(response)
  
          It will be called to process server continuation responses; the
          response argument it is passed will be a bytes.  It should return bytes
          data that will be base64 encoded and sent to the server.  It should
          return None if the client abort response '*' should be sent instead.
          """
          mech = mechanism.upper()
          # XXX: shouldn't this code be removed, not commented out?
          #cap = 'AUTH=%s' % mech
          #if not cap in self.capabilities:       # Let the server decide!
          #    raise self.error("Server doesn't allow %s authentication." % mech)
          self.literal = _Authenticator(authobject).process
          typ, dat = self._simple_command('AUTHENTICATE', mech)
          if typ != 'OK':
              raise self.error(dat[-1])
          self.state = 'AUTH'
          return typ, dat
  
  
      def capability(self):
          """(typ, [data]) = <instance>.capability()
          Fetch capabilities list from server."""
  
          name = 'CAPABILITY'
          typ, dat = self._simple_command(name)
          return self._untagged_response(typ, dat, name)
  
  
      def check(self):
          """Checkpoint mailbox on server.
  
          (typ, [data]) = <instance>.check()
          """
          return self._simple_command('CHECK')
  
  
      def close(self):
          """Close currently selected mailbox.
  
          Deleted messages are removed from writable mailbox.
          This is the recommended command before 'LOGOUT'.
  
          (typ, [data]) = <instance>.close()
          """
          try:
              typ, dat = self._simple_command('CLOSE')
          finally:
              self.state = 'AUTH'
          return typ, dat
  
  
      def copy(self, message_set, new_mailbox):
          """Copy 'message_set' messages onto end of 'new_mailbox'.
  
          (typ, [data]) = <instance>.copy(message_set, new_mailbox)
          """
          return self._simple_command('COPY', message_set, new_mailbox)
  
  
      def create(self, mailbox):
          """Create new mailbox.
  
          (typ, [data]) = <instance>.create(mailbox)
          """
          return self._simple_command('CREATE', mailbox)
  
  
      def delete(self, mailbox):
          """Delete old mailbox.
  
          (typ, [data]) = <instance>.delete(mailbox)
          """
          return self._simple_command('DELETE', mailbox)
  
      def deleteacl(self, mailbox, who):
          """Delete the ACLs (remove any rights) set for who on mailbox.
  
          (typ, [data]) = <instance>.deleteacl(mailbox, who)
          """
          return self._simple_command('DELETEACL', mailbox, who)
  
      def expunge(self):
          """Permanently remove deleted items from selected mailbox.
  
          Generates 'EXPUNGE' response for each deleted message.
  
          (typ, [data]) = <instance>.expunge()
  
          'data' is list of 'EXPUNGE'd message numbers in order received.
          """
          name = 'EXPUNGE'
          typ, dat = self._simple_command(name)
          return self._untagged_response(typ, dat, name)
  
  
      def fetch(self, message_set, message_parts):
          """Fetch (parts of) messages.
  
          (typ, [data, ...]) = <instance>.fetch(message_set, message_parts)
  
          'message_parts' should be a string of selected parts
          enclosed in parentheses, eg: "(UID BODY[TEXT])".
  
          'data' are tuples of message part envelope and data.
          """
          name = 'FETCH'
          typ, dat = self._simple_command(name, message_set, message_parts)
          return self._untagged_response(typ, dat, name)
  
  
      def getacl(self, mailbox):
          """Get the ACLs for a mailbox.
  
          (typ, [data]) = <instance>.getacl(mailbox)
          """
          typ, dat = self._simple_command('GETACL', mailbox)
          return self._untagged_response(typ, dat, 'ACL')
  
  
      def getannotation(self, mailbox, entry, attribute):
          """(typ, [data]) = <instance>.getannotation(mailbox, entry, attribute)
          Retrieve ANNOTATIONs."""
  
          typ, dat = self._simple_command('GETANNOTATION', mailbox, entry, attribute)
          return self._untagged_response(typ, dat, 'ANNOTATION')
  
  
      def getquota(self, root):
          """Get the quota root's resource usage and limits.
  
          Part of the IMAP4 QUOTA extension defined in rfc2087.
  
          (typ, [data]) = <instance>.getquota(root)
          """
          typ, dat = self._simple_command('GETQUOTA', root)
          return self._untagged_response(typ, dat, 'QUOTA')
  
  
      def getquotaroot(self, mailbox):
          """Get the list of quota roots for the named mailbox.
  
          (typ, [[QUOTAROOT responses...], [QUOTA responses]]) = <instance>.getquotaroot(mailbox)
          """
          typ, dat = self._simple_command('GETQUOTAROOT', mailbox)
          typ, quota = self._untagged_response(typ, dat, 'QUOTA')
          typ, quotaroot = self._untagged_response(typ, dat, 'QUOTAROOT')
          return typ, [quotaroot, quota]
  
  
      def list(self, directory='""', pattern='*'):
          """List mailbox names in directory matching pattern.
  
          (typ, [data]) = <instance>.list(directory='""', pattern='*')
  
          'data' is list of LIST responses.
          """
          name = 'LIST'
          typ, dat = self._simple_command(name, directory, pattern)
          return self._untagged_response(typ, dat, name)
  
  
      def login(self, user, password):
          """Identify client using plaintext password.
  
          (typ, [data]) = <instance>.login(user, password)
  
          NB: 'password' will be quoted.
          """
          typ, dat = self._simple_command('LOGIN', user, self._quote(password))
          if typ != 'OK':
              raise self.error(dat[-1])
          self.state = 'AUTH'
          return typ, dat
  
  
      def login_cram_md5(self, user, password):
          """ Force use of CRAM-MD5 authentication.
  
          (typ, [data]) = <instance>.login_cram_md5(user, password)
          """
          self.user, self.password = user, password
          return self.authenticate('CRAM-MD5', self._CRAM_MD5_AUTH)
  
  
      def _CRAM_MD5_AUTH(self, challenge):
          """ Authobject to use with CRAM-MD5 authentication. """
          import hmac
          pwd = (self.password.encode('ASCII') if isinstance(self.password, str)
                                               else self.password)
          return self.user + " " + hmac.HMAC(pwd, challenge).hexdigest()
  
  
      def logout(self):
          """Shutdown connection to server.
  
          (typ, [data]) = <instance>.logout()
  
          Returns server 'BYE' response.
          """
          self.state = 'LOGOUT'
          try: typ, dat = self._simple_command('LOGOUT')
          except: typ, dat = 'NO', ['%s: %s' % sys.exc_info()[:2]]
          self.shutdown()
          if 'BYE' in self.untagged_responses:
              return 'BYE', self.untagged_responses['BYE']
          return typ, dat
  
  
      def lsub(self, directory='""', pattern='*'):
          """List 'subscribed' mailbox names in directory matching pattern.
  
          (typ, [data, ...]) = <instance>.lsub(directory='""', pattern='*')
  
          'data' are tuples of message part envelope and data.
          """
          name = 'LSUB'
          typ, dat = self._simple_command(name, directory, pattern)
          return self._untagged_response(typ, dat, name)
  
      def myrights(self, mailbox):
          """Show my ACLs for a mailbox (i.e. the rights that I have on mailbox).
  
          (typ, [data]) = <instance>.myrights(mailbox)
          """
          typ,dat = self._simple_command('MYRIGHTS', mailbox)
          return self._untagged_response(typ, dat, 'MYRIGHTS')
  
      def namespace(self):
          """ Returns IMAP namespaces ala rfc2342
  
          (typ, [data, ...]) = <instance>.namespace()
          """
          name = 'NAMESPACE'
          typ, dat = self._simple_command(name)
          return self._untagged_response(typ, dat, name)
  
  
      def noop(self):
          """Send NOOP command.
  
          (typ, [data]) = <instance>.noop()
          """
          if __debug__:
              if self.debug >= 3:
                  self._dump_ur(self.untagged_responses)
          return self._simple_command('NOOP')
  
  
      def partial(self, message_num, message_part, start, length):
          """Fetch truncated part of a message.
  
          (typ, [data, ...]) = <instance>.partial(message_num, message_part, start, length)
  
          'data' is tuple of message part envelope and data.
          """
          name = 'PARTIAL'
          typ, dat = self._simple_command(name, message_num, message_part, start, length)
          return self._untagged_response(typ, dat, 'FETCH')
  
  
      def proxyauth(self, user):
          """Assume authentication as "user".
  
          Allows an authorised administrator to proxy into any user's
          mailbox.
  
          (typ, [data]) = <instance>.proxyauth(user)
          """
  
          name = 'PROXYAUTH'
          return self._simple_command('PROXYAUTH', user)
  
  
      def rename(self, oldmailbox, newmailbox):
          """Rename old mailbox name to new.
  
          (typ, [data]) = <instance>.rename(oldmailbox, newmailbox)
          """
          return self._simple_command('RENAME', oldmailbox, newmailbox)
  
  
      def search(self, charset, *criteria):
          """Search mailbox for matching messages.
  
          (typ, [data]) = <instance>.search(charset, criterion, ...)
  
          'data' is space separated list of matching message numbers.
          """
          name = 'SEARCH'
          if charset:
              typ, dat = self._simple_command(name, 'CHARSET', charset, *criteria)
          else:
              typ, dat = self._simple_command(name, *criteria)
          return self._untagged_response(typ, dat, name)
  
  
      def select(self, mailbox='INBOX', readonly=False):
          """Select a mailbox.
  
          Flush all untagged responses.
  
          (typ, [data]) = <instance>.select(mailbox='INBOX', readonly=False)
  
          'data' is count of messages in mailbox ('EXISTS' response).
  
          Mandated responses are ('FLAGS', 'EXISTS', 'RECENT', 'UIDVALIDITY'), so
          other responses should be obtained via <instance>.response('FLAGS') etc.
          """
          self.untagged_responses = {}    # Flush old responses.
          self.is_readonly = readonly
          if readonly:
              name = 'EXAMINE'
          else:
              name = 'SELECT'
          typ, dat = self._simple_command(name, mailbox)
          if typ != 'OK':
              self.state = 'AUTH'     # Might have been 'SELECTED'
              return typ, dat
          self.state = 'SELECTED'
          if 'READ-ONLY' in self.untagged_responses \
                  and not readonly:
              if __debug__:
                  if self.debug >= 1:
                      self._dump_ur(self.untagged_responses)
              raise self.readonly('%s is not writable' % mailbox)
          return typ, self.untagged_responses.get('EXISTS', [None])
  
  
      def setacl(self, mailbox, who, what):
          """Set a mailbox acl.
  
          (typ, [data]) = <instance>.setacl(mailbox, who, what)
          """
          return self._simple_command('SETACL', mailbox, who, what)
  
  
      def setannotation(self, *args):
          """(typ, [data]) = <instance>.setannotation(mailbox[, entry, attribute]+)
          Set ANNOTATIONs."""
  
          typ, dat = self._simple_command('SETANNOTATION', *args)
          return self._untagged_response(typ, dat, 'ANNOTATION')
  
  
      def setquota(self, root, limits):
          """Set the quota root's resource limits.
  
          (typ, [data]) = <instance>.setquota(root, limits)
          """
          typ, dat = self._simple_command('SETQUOTA', root, limits)
          return self._untagged_response(typ, dat, 'QUOTA')
  
  
      def sort(self, sort_criteria, charset, *search_criteria):
          """IMAP4rev1 extension SORT command.
  
          (typ, [data]) = <instance>.sort(sort_criteria, charset, search_criteria, ...)
          """
          name = 'SORT'
          #if not name in self.capabilities:      # Let the server decide!
          #       raise self.error('unimplemented extension command: %s' % name)
          if (sort_criteria[0],sort_criteria[-1]) != ('(',')'):
              sort_criteria = '(%s)' % sort_criteria
          typ, dat = self._simple_command(name, sort_criteria, charset, *search_criteria)
          return self._untagged_response(typ, dat, name)
  
  
      def starttls(self, ssl_context=None):
          name = 'STARTTLS'
          if not HAVE_SSL:
              raise self.error('SSL support missing')
          if self._tls_established:
              raise self.abort('TLS session already established')
          if name not in self.capabilities:
              raise self.abort('TLS not supported by server')
          # Generate a default SSL context if none was passed.
          if ssl_context is None:
              ssl_context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
              # SSLv2 considered harmful.
              ssl_context.options |= ssl.OP_NO_SSLv2
          typ, dat = self._simple_command(name)
          if typ == 'OK':
              self.sock = ssl_context.wrap_socket(self.sock)
              self.file = self.sock.makefile('rb')
              self._tls_established = True
              self._get_capabilities()
          else:
              raise self.error("Couldn't establish TLS session")
          return self._untagged_response(typ, dat, name)
  
  
      def status(self, mailbox, names):
          """Request named status conditions for mailbox.
  
          (typ, [data]) = <instance>.status(mailbox, names)
          """
          name = 'STATUS'
          #if self.PROTOCOL_VERSION == 'IMAP4':   # Let the server decide!
          #    raise self.error('%s unimplemented in IMAP4 (obtain IMAP4rev1 server, or re-code)' % name)
          typ, dat = self._simple_command(name, mailbox, names)
          return self._untagged_response(typ, dat, name)
  
  
      def store(self, message_set, command, flags):
          """Alters flag dispositions for messages in mailbox.
  
          (typ, [data]) = <instance>.store(message_set, command, flags)
          """
          if (flags[0],flags[-1]) != ('(',')'):
              flags = '(%s)' % flags  # Avoid quoting the flags
          typ, dat = self._simple_command('STORE', message_set, command, flags)
          return self._untagged_response(typ, dat, 'FETCH')
  
  
      def subscribe(self, mailbox):
          """Subscribe to new mailbox.
  
          (typ, [data]) = <instance>.subscribe(mailbox)
          """
          return self._simple_command('SUBSCRIBE', mailbox)
  
  
      def thread(self, threading_algorithm, charset, *search_criteria):
          """IMAPrev1 extension THREAD command.
  
          (type, [data]) = <instance>.thread(threading_algorithm, charset, search_criteria, ...)
          """
          name = 'THREAD'
          typ, dat = self._simple_command(name, threading_algorithm, charset, *search_criteria)
          return self._untagged_response(typ, dat, name)
  
  
      def uid(self, command, *args):
          """Execute "command arg ..." with messages identified by UID,
                  rather than message number.
  
          (typ, [data]) = <instance>.uid(command, arg1, arg2, ...)
  
          Returns response appropriate to 'command'.
          """
          command = command.upper()
          if not command in Commands:
              raise self.error("Unknown IMAP4 UID command: %s" % command)
          if self.state not in Commands[command]:
              raise self.error("command %s illegal in state %s, "
                               "only allowed in states %s" %
                               (command, self.state,
                                ', '.join(Commands[command])))
          name = 'UID'
          typ, dat = self._simple_command(name, command, *args)
          if command in ('SEARCH', 'SORT', 'THREAD'):
              name = command
          else:
              name = 'FETCH'
          return self._untagged_response(typ, dat, name)
  
  
      def unsubscribe(self, mailbox):
          """Unsubscribe from old mailbox.
  
          (typ, [data]) = <instance>.unsubscribe(mailbox)
          """
          return self._simple_command('UNSUBSCRIBE', mailbox)
  
  
      def xatom(self, name, *args):
          """Allow simple extension commands
                  notified by server in CAPABILITY response.
  
          Assumes command is legal in current state.
  
          (typ, [data]) = <instance>.xatom(name, arg, ...)
  
          Returns response appropriate to extension command `name'.
          """
          name = name.upper()
          #if not name in self.capabilities:      # Let the server decide!
          #    raise self.error('unknown extension command: %s' % name)
          if not name in Commands:
              Commands[name] = (self.state,)
          return self._simple_command(name, *args)
  
  
  
      #       Private methods
  
  
      def _append_untagged(self, typ, dat):
          if dat is None:
              dat = b''
          ur = self.untagged_responses
          if __debug__:
              if self.debug >= 5:
                  self._mesg('untagged_responses[%s] %s += ["%r"]' %
                          (typ, len(ur.get(typ,'')), dat))
          if typ in ur:
              ur[typ].append(dat)
          else:
              ur[typ] = [dat]
  
  
      def _check_bye(self):
          bye = self.untagged_responses.get('BYE')
          if bye:
              raise self.abort(bye[-1].decode('ascii', 'replace'))
  
  
      def _command(self, name, *args):
  
          if self.state not in Commands[name]:
              self.literal = None
              raise self.error("command %s illegal in state %s, "
                               "only allowed in states %s" %
                               (name, self.state,
                                ', '.join(Commands[name])))
  
          for typ in ('OK', 'NO', 'BAD'):
              if typ in self.untagged_responses:
                  del self.untagged_responses[typ]
  
          if 'READ-ONLY' in self.untagged_responses \
          and not self.is_readonly:
              raise self.readonly('mailbox status changed to READ-ONLY')
  
          tag = self._new_tag()
          name = bytes(name, 'ASCII')
          data = tag + b' ' + name
          for arg in args:
              if arg is None: continue
              if isinstance(arg, str):
                  arg = bytes(arg, "ASCII")
              data = data + b' ' + arg
  
          literal = self.literal
          if literal is not None:
              self.literal = None
              if type(literal) is type(self._command):
                  literator = literal
              else:
                  literator = None
                  data = data + bytes(' {%s}' % len(literal), 'ASCII')
  
          if __debug__:
              if self.debug >= 4:
                  self._mesg('> %r' % data)
              else:
                  self._log('> %r' % data)
  
          try:
              self.send(data + CRLF)
          except (socket.error, OSError) as val:
              raise self.abort('socket error: %s' % val)
  
          if literal is None:
              return tag
  
          while 1:
              # Wait for continuation response
  
              while self._get_response():
                  if self.tagged_commands[tag]:   # BAD/NO?
                      return tag
  
              # Send literal
  
              if literator:
                  literal = literator(self.continuation_response)
  
              if __debug__:
                  if self.debug >= 4:
                      self._mesg('write literal size %s' % len(literal))
  
              try:
                  self.send(literal)
                  self.send(CRLF)
              except (socket.error, OSError) as val:
                  raise self.abort('socket error: %s' % val)
  
              if not literator:
                  break
  
          return tag
  
  
      def _command_complete(self, name, tag):
          # BYE is expected after LOGOUT
          if name != 'LOGOUT':
              self._check_bye()
          try:
              typ, data = self._get_tagged_response(tag)
          except self.abort as val:
              raise self.abort('command: %s => %s' % (name, val))
          except self.error as val:
              raise self.error('command: %s => %s' % (name, val))
          if name != 'LOGOUT':
              self._check_bye()
          if typ == 'BAD':
              raise self.error('%s command error: %s %s' % (name, typ, data))
          return typ, data
  
  
      def _get_capabilities(self):
          typ, dat = self.capability()
          if dat == [None]:
              raise self.error('no CAPABILITY response from server')
          dat = str(dat[-1], "ASCII")
          dat = dat.upper()
          self.capabilities = tuple(dat.split())
  
  
      def _get_response(self):
  
          # Read response and store.
          #
          # Returns None for continuation responses,
          # otherwise first response line received.
  
          resp = self._get_line()
  
          # Command completion response?
  
          if self._match(self.tagre, resp):
              tag = self.mo.group('tag')
              if not tag in self.tagged_commands:
                  raise self.abort('unexpected tagged response: %s' % resp)
  
              typ = self.mo.group('type')
              typ = str(typ, 'ASCII')
              dat = self.mo.group('data')
              self.tagged_commands[tag] = (typ, [dat])
          else:
              dat2 = None
  
              # '*' (untagged) responses?
  
              if not self._match(Untagged_response, resp):
                  if self._match(Untagged_status, resp):
                      dat2 = self.mo.group('data2')
  
              if self.mo is None:
                  # Only other possibility is '+' (continuation) response...
  
                  if self._match(Continuation, resp):
                      self.continuation_response = self.mo.group('data')
                      return None     # NB: indicates continuation
  
                  raise self.abort("unexpected response: '%s'" % resp)
  
              typ = self.mo.group('type')
              typ = str(typ, 'ascii')
              dat = self.mo.group('data')
              if dat is None: dat = b''        # Null untagged response
              if dat2: dat = dat + b' ' + dat2
  
              # Is there a literal to come?
  
              while self._match(Literal, dat):
  
                  # Read literal direct from connection.
  
                  size = int(self.mo.group('size'))
                  if __debug__:
                      if self.debug >= 4:
                          self._mesg('read literal size %s' % size)
                  data = self.read(size)
  
                  # Store response with literal as tuple
  
                  self._append_untagged(typ, (dat, data))
  
                  # Read trailer - possibly containing another literal
  
                  dat = self._get_line()
  
              self._append_untagged(typ, dat)
  
          # Bracketed response information?
  
          if typ in ('OK', 'NO', 'BAD') and self._match(Response_code, dat):
              typ = self.mo.group('type')
              typ = str(typ, "ASCII")
              self._append_untagged(typ, self.mo.group('data'))
  
          if __debug__:
              if self.debug >= 1 and typ in ('NO', 'BAD', 'BYE'):
                  self._mesg('%s response: %r' % (typ, dat))
  
          return resp
  
  
      def _get_tagged_response(self, tag):
  
          while 1:
              result = self.tagged_commands[tag]
              if result is not None:
                  del self.tagged_commands[tag]
                  return result
  
              # Some have reported "unexpected response" exceptions.
              # Note that ignoring them here causes loops.
              # Instead, send me details of the unexpected response and
              # I'll update the code in `_get_response()'.
  
              try:
                  self._get_response()
              except self.abort as val:
                  if __debug__:
                      if self.debug >= 1:
                          self.print_log()
                  raise
  
  
      def _get_line(self):
  
          line = self.readline()
          if not line:
              raise self.abort('socket error: EOF')
  
          # Protocol mandates all lines terminated by CRLF
          if not line.endswith(b'\r\n'):
              raise self.abort('socket error: unterminated line')
  
          line = line[:-2]
          if __debug__:
              if self.debug >= 4:
                  self._mesg('< %r' % line)
              else:
                  self._log('< %r' % line)
          return line
  
  
      def _match(self, cre, s):
  
          # Run compiled regular expression match method on 's'.
          # Save result, return success.
  
          self.mo = cre.match(s)
          if __debug__:
              if self.mo is not None and self.debug >= 5:
                  self._mesg("\tmatched r'%r' => %r" % (cre.pattern, self.mo.groups()))
          return self.mo is not None
  
  
      def _new_tag(self):
  
          tag = self.tagpre + bytes(str(self.tagnum), 'ASCII')
          self.tagnum = self.tagnum + 1
          self.tagged_commands[tag] = None
          return tag
  
  
      def _quote(self, arg):
  
          arg = arg.replace('\\', '\\\\')
          arg = arg.replace('"', '\\"')
  
          return '"' + arg + '"'
  
  
      def _simple_command(self, name, *args):
  
          return self._command_complete(name, self._command(name, *args))
  
  
      def _untagged_response(self, typ, dat, name):
          if typ == 'NO':
              return typ, dat
          if not name in self.untagged_responses:
              return typ, [None]
          data = self.untagged_responses.pop(name)
          if __debug__:
              if self.debug >= 5:
                  self._mesg('untagged_responses[%s] => %s' % (name, data))
          return typ, data
  
  
      if __debug__:
  
          def _mesg(self, s, secs=None):
              if secs is None:
                  secs = time.time()
              tm = time.strftime('%M:%S', time.localtime(secs))
              sys.stderr.write('  %s.%02d %s\n' % (tm, (secs*100)%100, s))
              sys.stderr.flush()
  
          def _dump_ur(self, dict):
              # Dump untagged responses (in `dict').
              l = dict.items()
              if not l: return
              t = '\n\t\t'
              l = map(lambda x:'%s: "%s"' % (x[0], x[1][0] and '" "'.join(x[1]) or ''), l)
              self._mesg('untagged responses dump:%s%s' % (t, t.join(l)))
  
          def _log(self, line):
              # Keep log of last `_cmd_log_len' interactions for debugging.
              self._cmd_log[self._cmd_log_idx] = (line, time.time())
              self._cmd_log_idx += 1
              if self._cmd_log_idx >= self._cmd_log_len:
                  self._cmd_log_idx = 0
  
          def print_log(self):
              self._mesg('last %d IMAP4 interactions:' % len(self._cmd_log))
              i, n = self._cmd_log_idx, self._cmd_log_len
              while n:
                  try:
                      self._mesg(*self._cmd_log[i])
                  except:
                      pass
                  i += 1
                  if i >= self._cmd_log_len:
                      i = 0
                  n -= 1
  
  
  if HAVE_SSL:
  
      class IMAP4_SSL(IMAP4):
  
          """IMAP4 client class over SSL connection
  
          Instantiate with: IMAP4_SSL([host[, port[, keyfile[, certfile]]]])
  
                  host - host's name (default: localhost);
                  port - port number (default: standard IMAP4 SSL port).
                  keyfile - PEM formatted file that contains your private key (default: None);
                  certfile - PEM formatted certificate chain file (default: None);
  
          for more documentation see the docstring of the parent class IMAP4.
          """
  
  
          def __init__(self, host = '', port = IMAP4_SSL_PORT, keyfile = None, certfile = None):
              self.keyfile = keyfile
              self.certfile = certfile
              IMAP4.__init__(self, host, port)
  
          def _create_socket(self):
              sock = IMAP4._create_socket(self)
              return ssl.wrap_socket(sock, self.keyfile, self.certfile)
  
          def open(self, host='', port=IMAP4_SSL_PORT):
              """Setup connection to remote server on "host:port".
                  (default: localhost:standard IMAP4 SSL port).
              This connection will be used by the routines:
                  read, readline, send, shutdown.
              """
              IMAP4.open(self, host, port)
  
      __all__.append("IMAP4_SSL")
  
  
  class IMAP4_stream(IMAP4):
  
      """IMAP4 client class over a stream
  
      Instantiate with: IMAP4_stream(command)
  
              where "command" is a string that can be passed to subprocess.Popen()
  
      for more documentation see the docstring of the parent class IMAP4.
      """
  
  
      def __init__(self, command):
          self.command = command
          IMAP4.__init__(self)
  
  
      def open(self, host = None, port = None):
          """Setup a stream connection.
          This connection will be used by the routines:
              read, readline, send, shutdown.
          """
          self.host = None        # For compatibility with parent class
          self.port = None
          self.sock = None
          self.file = None
          self.process = subprocess.Popen(self.command,
              bufsize=DEFAULT_BUFFER_SIZE,
              stdin=subprocess.PIPE, stdout=subprocess.PIPE,
              shell=True, close_fds=True)
          self.writefile = self.process.stdin
          self.readfile = self.process.stdout
  
      def read(self, size):
          """Read 'size' bytes from remote."""
          return self.readfile.read(size)
  
  
      def readline(self):
          """Read line from remote."""
          return self.readfile.readline()
  
  
      def send(self, data):
          """Send data to remote."""
          self.writefile.write(data)
          self.writefile.flush()
  
  
      def shutdown(self):
          """Close I/O established in "open"."""
          self.readfile.close()
          self.writefile.close()
          self.process.wait()
  
  
  
  class _Authenticator:
  
      """Private class to provide en/decoding
              for base64-based authentication conversation.
      """
  
      def __init__(self, mechinst):
          self.mech = mechinst    # Callable object to provide/process data
  
      def process(self, data):
          ret = self.mech(self.decode(data))
          if ret is None:
              return '*'      # Abort conversation
          return self.encode(ret)
  
      def encode(self, inp):
          #
          #  Invoke binascii.b2a_base64 iteratively with
          #  short even length buffers, strip the trailing
          #  line feed from the result and append.  "Even"
          #  means a number that factors to both 6 and 8,
          #  so when it gets to the end of the 8-bit input
          #  there's no partial 6-bit output.
          #
          oup = b''
          if isinstance(inp, str):
              inp = inp.encode('ASCII')
          while inp:
              if len(inp) > 48:
                  t = inp[:48]
                  inp = inp[48:]
              else:
                  t = inp
                  inp = b''
              e = binascii.b2a_base64(t)
              if e:
                  oup = oup + e[:-1]
          return oup
  
      def decode(self, inp):
          if not inp:
              return b''
          return binascii.a2b_base64(inp)
  
  
  
  Mon2num = {b'Jan': 1, b'Feb': 2, b'Mar': 3, b'Apr': 4, b'May': 5, b'Jun': 6,
             b'Jul': 7, b'Aug': 8, b'Sep': 9, b'Oct': 10, b'Nov': 11, b'Dec': 12}
  
  def Internaldate2tuple(resp):
      """Parse an IMAP4 INTERNALDATE string.
  
      Return corresponding local time.  The return value is a
      time.struct_time tuple or None if the string has wrong format.
      """
  
      mo = InternalDate.match(resp)
      if not mo:
          return None
  
      mon = Mon2num[mo.group('mon')]
      zonen = mo.group('zonen')
  
      day = int(mo.group('day'))
      year = int(mo.group('year'))
      hour = int(mo.group('hour'))
      min = int(mo.group('min'))
      sec = int(mo.group('sec'))
      zoneh = int(mo.group('zoneh'))
      zonem = int(mo.group('zonem'))
  
      # INTERNALDATE timezone must be subtracted to get UT
  
      zone = (zoneh*60 + zonem)*60
      if zonen == b'-':
          zone = -zone
  
      tt = (year, mon, day, hour, min, sec, -1, -1, -1)
      utc = calendar.timegm(tt) - zone
  
      return time.localtime(utc)
  
  
  
  def Int2AP(num):
  
      """Convert integer to A-P string representation."""
  
      val = b''; AP = b'ABCDEFGHIJKLMNOP'
      num = int(abs(num))
      while num:
          num, mod = divmod(num, 16)
          val = AP[mod:mod+1] + val
      return val
  
  
  
  def ParseFlags(resp):
  
      """Convert IMAP4 flags response to python tuple."""
  
      mo = Flags.match(resp)
      if not mo:
          return ()
  
      return tuple(mo.group('flags').split())
  
  
  def Time2Internaldate(date_time):
  
      """Convert date_time to IMAP4 INTERNALDATE representation.
  
      Return string in form: '"DD-Mmm-YYYY HH:MM:SS +HHMM"'.  The
      date_time argument can be a number (int or float) representing
      seconds since epoch (as returned by time.time()), a 9-tuple
      representing local time (as returned by time.localtime()), or a
      double-quoted string.  In the last case, it is assumed to already
      be in the correct format.
      """
  
      if isinstance(date_time, (int, float)):
          tt = time.localtime(date_time)
      elif isinstance(date_time, (tuple, time.struct_time)):
          tt = date_time
      elif isinstance(date_time, str) and (date_time[0],date_time[-1]) == ('"','"'):
          return date_time        # Assume in correct format
      else:
          raise ValueError("date_time not of a known type")
  
      dt = time.strftime("%d-%b-%Y %H:%M:%S", tt)
      if dt[0] == '0':
          dt = ' ' + dt[1:]
      if time.daylight and tt[-1]:
          zone = -time.altzone
      else:
          zone = -time.timezone
      return '"' + dt + " %+03d%02d" % divmod(zone//60, 60) + '"'
  
  
  
  if __name__ == '__main__':
  
      # To test: invoke either as 'python imaplib.py [IMAP4_server_hostname]'
      # or 'python imaplib.py -s "rsh IMAP4_server_hostname exec /etc/rimapd"'
      # to test the IMAP4_stream class
  
      import getopt, getpass
  
      try:
          optlist, args = getopt.getopt(sys.argv[1:], 'd:s:')
      except getopt.error as val:
          optlist, args = (), ()
  
      stream_command = None
      for opt,val in optlist:
          if opt == '-d':
              Debug = int(val)
          elif opt == '-s':
              stream_command = val
              if not args: args = (stream_command,)
  
      if not args: args = ('',)
  
      host = args[0]
  
      USER = getpass.getuser()
      PASSWD = getpass.getpass("IMAP password for %s on %s: " % (USER, host or "localhost"))
  
      test_mesg = 'From: %(user)s@localhost%(lf)sSubject: IMAP4 test%(lf)s%(lf)sdata...%(lf)s' % {'user':USER, 'lf':'\n'}
      test_seq1 = (
      ('login', (USER, PASSWD)),
      ('create', ('/tmp/xxx 1',)),
      ('rename', ('/tmp/xxx 1', '/tmp/yyy')),
      ('CREATE', ('/tmp/yyz 2',)),
      ('append', ('/tmp/yyz 2', None, None, test_mesg)),
      ('list', ('/tmp', 'yy*')),
      ('select', ('/tmp/yyz 2',)),
      ('search', (None, 'SUBJECT', 'test')),
      ('fetch', ('1', '(FLAGS INTERNALDATE RFC822)')),
      ('store', ('1', 'FLAGS', '(\Deleted)')),
      ('namespace', ()),
      ('expunge', ()),
      ('recent', ()),
      ('close', ()),
      )
  
      test_seq2 = (
      ('select', ()),
      ('response',('UIDVALIDITY',)),
      ('uid', ('SEARCH', 'ALL')),
      ('response', ('EXISTS',)),
      ('append', (None, None, None, test_mesg)),
      ('recent', ()),
      ('logout', ()),
      )
  
      def run(cmd, args):
          M._mesg('%s %s' % (cmd, args))
          typ, dat = getattr(M, cmd)(*args)
          M._mesg('%s => %s %s' % (cmd, typ, dat))
          if typ == 'NO': raise dat[0]
          return dat
  
      try:
          if stream_command:
              M = IMAP4_stream(stream_command)
          else:
              M = IMAP4(host)
          if M.state == 'AUTH':
              test_seq1 = test_seq1[1:]   # Login not needed
          M._mesg('PROTOCOL_VERSION = %s' % M.PROTOCOL_VERSION)
          M._mesg('CAPABILITIES = %r' % (M.capabilities,))
  
          for cmd,args in test_seq1:
              run(cmd, args)
  
          for ml in run('list', ('/tmp/', 'yy%')):
              mo = re.match(r'.*"([^"]+)"$', ml)
              if mo: path = mo.group(1)
              else: path = ml.split()[-1]
              run('delete', (path,))
  
          for cmd,args in test_seq2:
              dat = run(cmd, args)
  
              if (cmd,args) != ('uid', ('SEARCH', 'ALL')):
                  continue
  
              uid = dat[-1].split()
              if not uid: continue
              run('uid', ('FETCH', '%s' % uid[-1],
                      '(FLAGS INTERNALDATE RFC822.SIZE RFC822.HEADER RFC822.TEXT)'))
  
          print('\nAll tests OK.')
  
      except:
          print('\nTests failed.')
  
          if not Debug:
              print('''
  If you would like to see debugging output,
  try: %s -d5
  ''' % sys.argv[0])
  
          raise
  