[telemetry] Add Monsoon protocol library.

tools/telemetry/third_party/pyserial/serial/rfc2217.py

Index: tools/telemetry/third_party/pyserial/serial/rfc2217.py
diff --git a/tools/telemetry/third_party/pyserial/serial/rfc2217.py b/tools/telemetry/third_party/pyserial/serial/rfc2217.py
new file mode 100644
index 0000000000000000000000000000000000000000..2012ea71c11667f3d93fb6ea1b634a8553b8c56b
--- /dev/null
+++ b/tools/telemetry/third_party/pyserial/serial/rfc2217.py
@@ -0,0 +1,1323 @@
+#! python
+#
+# Python Serial Port Extension for Win32, Linux, BSD, Jython
+# see __init__.py
+#
+# This module implements a RFC2217 compatible client. RF2217 descibes a
+# protocol to access serial ports over TCP/IP and allows setting the baud rate,
+# modem control lines etc.
+#
+# (C) 2001-2013 Chris Liechti <cliechti@gmx.net>
+# this is distributed under a free software license, see license.txt
+
+# TODO:
+# - setting control line -> answer is not checked (had problems with one of the
+#   severs). consider implementing a compatibility mode flag to make check
+#   conditional
+# - write timeout not implemented at all
+
+##############################################################################
+# observations and issues with servers
+#=============================================================================
+# sredird V2.2.1
+# - http://www.ibiblio.org/pub/Linux/system/serial/   sredird-2.2.2.tar.gz
+# - does not acknowledge SET_CONTROL (RTS/DTR) correctly, always responding
+#   [105 1] instead of the actual value.
+# - SET_BAUDRATE answer contains 4 extra null bytes -> probably for larger
+#   numbers than 2**32?
+# - To get the signature [COM_PORT_OPTION 0] has to be sent.
+# - run a server: while true; do nc -l -p 7000 -c "sredird debug /dev/ttyUSB0 /var/lock/sredir"; done
+#=============================================================================
+# telnetcpcd (untested)
+# - http://ftp.wayne.edu/kermit/sredird/telnetcpcd-1.09.tar.gz
+# - To get the signature [COM_PORT_OPTION] w/o data has to be sent.
+#=============================================================================
+# ser2net
+# - does not negotiate BINARY or COM_PORT_OPTION for his side but at least
+#   acknowledges that the client activates these options
+# - The configuration may be that the server prints a banner. As this client
+#   implementation does a flushInput on connect, this banner is hidden from
+#   the user application.
+# - NOTIFY_MODEMSTATE: the poll interval of the server seems to be one
+#   second.
+# - To get the signature [COM_PORT_OPTION 0] has to be sent.
+# - run a server: run ser2net daemon, in /etc/ser2net.conf:
+#     2000:telnet:0:/dev/ttyS0:9600 remctl banner
+##############################################################################
+
+# How to identify ports? pySerial might want to support other protocols in the
+# future, so lets use an URL scheme.
+# for RFC2217 compliant servers we will use this:
+#    rfc2217://<host>:<port>[/option[/option...]]
+#
+# options:
+# - "debug" print diagnostic messages
+# - "ign_set_control": do not look at the answers to SET_CONTROL
+# - "poll_modem": issue NOTIFY_MODEMSTATE requests when CTS/DTR/RI/CD is read.
+#   Without this option it expects that the server sends notifications
+#   automatically on change (which most servers do and is according to the
+#   RFC).
+# the order of the options is not relevant
+
+from serial.serialutil import *
+import time
+import struct
+import socket
+import threading
+import Queue
+import logging
+
+# port string is expected to be something like this:
+# rfc2217://host:port
+# host may be an IP or including domain, whatever.
+# port is 0...65535
+
+# map log level names to constants. used in fromURL()
+LOGGER_LEVELS = {
+    'debug': logging.DEBUG,
+    'info': logging.INFO,
+    'warning': logging.WARNING,
+    'error': logging.ERROR,
+    }
+
+
+# telnet protocol characters
+IAC  = to_bytes([255]) # Interpret As Command
+DONT = to_bytes([254])
+DO   = to_bytes([253])
+WONT = to_bytes([252])
+WILL = to_bytes([251])
+IAC_DOUBLED = to_bytes([IAC, IAC])
+
+SE  = to_bytes([240])  # Subnegotiation End
+NOP = to_bytes([241])  # No Operation
+DM  = to_bytes([242])  # Data Mark
+BRK = to_bytes([243])  # Break
+IP  = to_bytes([244])  # Interrupt process
+AO  = to_bytes([245])  # Abort output
+AYT = to_bytes([246])  # Are You There
+EC  = to_bytes([247])  # Erase Character
+EL  = to_bytes([248])  # Erase Line
+GA  = to_bytes([249])  # Go Ahead
+SB =  to_bytes([250])  # Subnegotiation Begin
+
+# selected telnet options
+BINARY = to_bytes([0]) # 8-bit data path
+ECHO = to_bytes([1])   # echo
+SGA = to_bytes([3])    # suppress go ahead
+
+# RFC2217
+COM_PORT_OPTION = to_bytes([44])
+
+# Client to Access Server
+SET_BAUDRATE = to_bytes([1])
+SET_DATASIZE = to_bytes([2])
+SET_PARITY = to_bytes([3])
+SET_STOPSIZE = to_bytes([4])
+SET_CONTROL = to_bytes([5])
+NOTIFY_LINESTATE = to_bytes([6])
+NOTIFY_MODEMSTATE = to_bytes([7])
+FLOWCONTROL_SUSPEND = to_bytes([8])
+FLOWCONTROL_RESUME = to_bytes([9])
+SET_LINESTATE_MASK = to_bytes([10])
+SET_MODEMSTATE_MASK = to_bytes([11])
+PURGE_DATA = to_bytes([12])
+
+SERVER_SET_BAUDRATE = to_bytes([101])
+SERVER_SET_DATASIZE = to_bytes([102])
+SERVER_SET_PARITY = to_bytes([103])
+SERVER_SET_STOPSIZE = to_bytes([104])
+SERVER_SET_CONTROL = to_bytes([105])
+SERVER_NOTIFY_LINESTATE = to_bytes([106])
+SERVER_NOTIFY_MODEMSTATE = to_bytes([107])
+SERVER_FLOWCONTROL_SUSPEND = to_bytes([108])
+SERVER_FLOWCONTROL_RESUME = to_bytes([109])
+SERVER_SET_LINESTATE_MASK = to_bytes([110])
+SERVER_SET_MODEMSTATE_MASK = to_bytes([111])
+SERVER_PURGE_DATA = to_bytes([112])
+
+RFC2217_ANSWER_MAP = {
+    SET_BAUDRATE: SERVER_SET_BAUDRATE,
+    SET_DATASIZE: SERVER_SET_DATASIZE,
+    SET_PARITY: SERVER_SET_PARITY,
+    SET_STOPSIZE: SERVER_SET_STOPSIZE,
+    SET_CONTROL: SERVER_SET_CONTROL,
+    NOTIFY_LINESTATE: SERVER_NOTIFY_LINESTATE,
+    NOTIFY_MODEMSTATE: SERVER_NOTIFY_MODEMSTATE,
+    FLOWCONTROL_SUSPEND: SERVER_FLOWCONTROL_SUSPEND,
+    FLOWCONTROL_RESUME: SERVER_FLOWCONTROL_RESUME,
+    SET_LINESTATE_MASK: SERVER_SET_LINESTATE_MASK,
+    SET_MODEMSTATE_MASK: SERVER_SET_MODEMSTATE_MASK,
+    PURGE_DATA: SERVER_PURGE_DATA,
+}
+
+SET_CONTROL_REQ_FLOW_SETTING = to_bytes([0])        # Request Com Port Flow Control Setting (outbound/both)
+SET_CONTROL_USE_NO_FLOW_CONTROL = to_bytes([1])     # Use No Flow Control (outbound/both)
+SET_CONTROL_USE_SW_FLOW_CONTROL = to_bytes([2])     # Use XON/XOFF Flow Control (outbound/both)
+SET_CONTROL_USE_HW_FLOW_CONTROL = to_bytes([3])     # Use HARDWARE Flow Control (outbound/both)
+SET_CONTROL_REQ_BREAK_STATE = to_bytes([4])         # Request BREAK State
+SET_CONTROL_BREAK_ON = to_bytes([5])                # Set BREAK State ON
+SET_CONTROL_BREAK_OFF = to_bytes([6])               # Set BREAK State OFF
+SET_CONTROL_REQ_DTR = to_bytes([7])                 # Request DTR Signal State
+SET_CONTROL_DTR_ON = to_bytes([8])                  # Set DTR Signal State ON
+SET_CONTROL_DTR_OFF = to_bytes([9])                 # Set DTR Signal State OFF
+SET_CONTROL_REQ_RTS = to_bytes([10])                # Request RTS Signal State
+SET_CONTROL_RTS_ON = to_bytes([11])                 # Set RTS Signal State ON
+SET_CONTROL_RTS_OFF = to_bytes([12])                # Set RTS Signal State OFF
+SET_CONTROL_REQ_FLOW_SETTING_IN = to_bytes([13])    # Request Com Port Flow Control Setting (inbound)
+SET_CONTROL_USE_NO_FLOW_CONTROL_IN = to_bytes([14]) # Use No Flow Control (inbound)
+SET_CONTROL_USE_SW_FLOW_CONTOL_IN = to_bytes([15])  # Use XON/XOFF Flow Control (inbound)
+SET_CONTROL_USE_HW_FLOW_CONTOL_IN = to_bytes([16])  # Use HARDWARE Flow Control (inbound)
+SET_CONTROL_USE_DCD_FLOW_CONTROL = to_bytes([17])   # Use DCD Flow Control (outbound/both)
+SET_CONTROL_USE_DTR_FLOW_CONTROL = to_bytes([18])   # Use DTR Flow Control (inbound)
+SET_CONTROL_USE_DSR_FLOW_CONTROL = to_bytes([19])   # Use DSR Flow Control (outbound/both)
+
+LINESTATE_MASK_TIMEOUT = 128                # Time-out Error
+LINESTATE_MASK_SHIFTREG_EMPTY = 64          # Transfer Shift Register Empty
+LINESTATE_MASK_TRANSREG_EMPTY = 32          # Transfer Holding Register Empty
+LINESTATE_MASK_BREAK_DETECT = 16            # Break-detect Error
+LINESTATE_MASK_FRAMING_ERROR = 8            # Framing Error
+LINESTATE_MASK_PARTIY_ERROR = 4             # Parity Error
+LINESTATE_MASK_OVERRUN_ERROR = 2            # Overrun Error
+LINESTATE_MASK_DATA_READY = 1               # Data Ready
+
+MODEMSTATE_MASK_CD = 128                    # Receive Line Signal Detect (also known as Carrier Detect)
+MODEMSTATE_MASK_RI = 64                     # Ring Indicator
+MODEMSTATE_MASK_DSR = 32                    # Data-Set-Ready Signal State
+MODEMSTATE_MASK_CTS = 16                    # Clear-To-Send Signal State
+MODEMSTATE_MASK_CD_CHANGE = 8               # Delta Receive Line Signal Detect
+MODEMSTATE_MASK_RI_CHANGE = 4               # Trailing-edge Ring Detector
+MODEMSTATE_MASK_DSR_CHANGE = 2              # Delta Data-Set-Ready
+MODEMSTATE_MASK_CTS_CHANGE = 1              # Delta Clear-To-Send
+
+PURGE_RECEIVE_BUFFER = to_bytes([1])        # Purge access server receive data buffer
+PURGE_TRANSMIT_BUFFER = to_bytes([2])       # Purge access server transmit data buffer
+PURGE_BOTH_BUFFERS = to_bytes([3])          # Purge both the access server receive data buffer and the access server transmit data buffer
+
+
+RFC2217_PARITY_MAP = {
+    PARITY_NONE: 1,
+    PARITY_ODD: 2,
+    PARITY_EVEN: 3,
+    PARITY_MARK: 4,
+    PARITY_SPACE: 5,
+}
+RFC2217_REVERSE_PARITY_MAP = dict((v,k) for k,v in RFC2217_PARITY_MAP.items())
+
+RFC2217_STOPBIT_MAP = {
+    STOPBITS_ONE: 1,
+    STOPBITS_ONE_POINT_FIVE: 3,
+    STOPBITS_TWO: 2,
+}
+RFC2217_REVERSE_STOPBIT_MAP = dict((v,k) for k,v in RFC2217_STOPBIT_MAP.items())
+
+# Telnet filter states
+M_NORMAL = 0
+M_IAC_SEEN = 1
+M_NEGOTIATE = 2
+
+# TelnetOption and TelnetSubnegotiation states
+REQUESTED = 'REQUESTED'
+ACTIVE = 'ACTIVE'
+INACTIVE = 'INACTIVE'
+REALLY_INACTIVE = 'REALLY_INACTIVE'
+
+class TelnetOption(object):
+    """Manage a single telnet option, keeps track of DO/DONT WILL/WONT."""
+
+    def __init__(self, connection, name, option, send_yes, send_no, ack_yes, ack_no, initial_state, activation_callback=None):
+        """\
+        Initialize option.
+        :param connection: connection used to transmit answers
+        :param name: a readable name for debug outputs
+        :param send_yes: what to send when option is to be enabled.
+        :param send_no: what to send when option is to be disabled.
+        :param ack_yes: what to expect when remote agrees on option.
+        :param ack_no: what to expect when remote disagrees on option.
+        :param initial_state: options initialized with REQUESTED are tried to
+            be enabled on startup. use INACTIVE for all others.
+        """
+        self.connection = connection
+        self.name = name
+        self.option = option
+        self.send_yes = send_yes
+        self.send_no = send_no
+        self.ack_yes = ack_yes
+        self.ack_no = ack_no
+        self.state = initial_state
+        self.active = False
+        self.activation_callback = activation_callback
+
+    def __repr__(self):
+        """String for debug outputs"""
+        return "%s:%s(%s)" % (self.name, self.active, self.state)
+
+    def process_incoming(self, command):
+        """A DO/DONT/WILL/WONT was received for this option, update state and
+        answer when needed."""
+        if command == self.ack_yes:
+            if self.state is REQUESTED:
+                self.state = ACTIVE
+                self.active = True
+                if self.activation_callback is not None:
+                    self.activation_callback()
+            elif self.state is ACTIVE:
+                pass
+            elif self.state is INACTIVE:
+                self.state = ACTIVE
+                self.connection.telnetSendOption(self.send_yes, self.option)
+                self.active = True
+                if self.activation_callback is not None:
+                    self.activation_callback()
+            elif self.state is REALLY_INACTIVE:
+                self.connection.telnetSendOption(self.send_no, self.option)
+            else:
+                raise ValueError('option in illegal state %r' % self)
+        elif command == self.ack_no:
+            if self.state is REQUESTED:
+                self.state = INACTIVE
+                self.active = False
+            elif self.state is ACTIVE:
+                self.state = INACTIVE
+                self.connection.telnetSendOption(self.send_no, self.option)
+                self.active = False
+            elif self.state is INACTIVE:
+                pass
+            elif self.state is REALLY_INACTIVE:
+                pass
+            else:
+                raise ValueError('option in illegal state %r' % self)
+
+
+class TelnetSubnegotiation(object):
+    """\
+    A object to handle subnegotiation of options. In this case actually
+    sub-sub options for RFC 2217. It is used to track com port options.
+    """
+
+    def __init__(self, connection, name, option, ack_option=None):
+        if ack_option is None: ack_option = option
+        self.connection = connection
+        self.name = name
+        self.option = option
+        self.value = None
+        self.ack_option = ack_option
+        self.state = INACTIVE
+
+    def __repr__(self):
+        """String for debug outputs."""
+        return "%s:%s" % (self.name, self.state)
+
+    def set(self, value):
+        """\
+        request a change of the value. a request is sent to the server. if
+        the client needs to know if the change is performed he has to check the
+        state of this object.
+        """
+        self.value = value
+        self.state = REQUESTED
+        self.connection.rfc2217SendSubnegotiation(self.option, self.value)
+        if self.connection.logger:
+            self.connection.logger.debug("SB Requesting %s -> %r" % (self.name, self.value))
+
+    def isReady(self):
+        """\
+        check if answer from server has been received. when server rejects
+        the change, raise a ValueError.
+        """
+        if self.state == REALLY_INACTIVE:
+            raise ValueError("remote rejected value for option %r" % (self.name))
+        return self.state == ACTIVE
+    # add property to have a similar interface as TelnetOption
+    active = property(isReady)
+
+    def wait(self, timeout=3):
+        """\
+        wait until the subnegotiation has been acknowledged or timeout. It
+        can also throw a value error when the answer from the server does not
+        match the value sent.
+        """
+        timeout_time = time.time() + timeout
+        while time.time() < timeout_time:
+            time.sleep(0.05)    # prevent 100% CPU load
+            if self.isReady():
+                break
+        else:
+            raise SerialException("timeout while waiting for option %r" % (self.name))
+
+    def checkAnswer(self, suboption):
+        """\
+        check an incoming subnegotiation block. the parameter already has
+        cut off the header like sub option number and com port option value.
+        """
+        if self.value == suboption[:len(self.value)]:
+            self.state = ACTIVE
+        else:
+            # error propagation done in isReady
+            self.state = REALLY_INACTIVE
+        if self.connection.logger:
+            self.connection.logger.debug("SB Answer %s -> %r -> %s" % (self.name, suboption, self.state))
+
+
+class RFC2217Serial(SerialBase):
+    """Serial port implementation for RFC 2217 remote serial ports."""
+
+    BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
+                 9600, 19200, 38400, 57600, 115200)
+
+    def open(self):
+        """\
+        Open port with current settings. This may throw a SerialException
+        if the port cannot be opened.
+        """
+        self.logger = None
+        self._ignore_set_control_answer = False
+        self._poll_modem_state = False
+        self._network_timeout = 3
+        if self._port is None:
+            raise SerialException("Port must be configured before it can be used.")
+        if self._isOpen:
+            raise SerialException("Port is already open.")
+        try:
+            self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self._socket.connect(self.fromURL(self.portstr))
+            self._socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        except Exception, msg:
+            self._socket = None
+            raise SerialException("Could not open port %s: %s" % (self.portstr, msg))
+
+        self._socket.settimeout(5) # XXX good value?
+
+        # use a thread save queue as buffer. it also simplifies implementing
+        # the read timeout
+        self._read_buffer = Queue.Queue()
+        # to ensure that user writes does not interfere with internal
+        # telnet/rfc2217 options establish a lock
+        self._write_lock = threading.Lock()
+        # name the following separately so that, below, a check can be easily done
+        mandadory_options = [
+            TelnetOption(self, 'we-BINARY', BINARY, WILL, WONT, DO, DONT, INACTIVE),
+            TelnetOption(self, 'we-RFC2217', COM_PORT_OPTION, WILL, WONT, DO, DONT, REQUESTED),
+        ]
+        # all supported telnet options
+        self._telnet_options = [
+            TelnetOption(self, 'ECHO', ECHO, DO, DONT, WILL, WONT, REQUESTED),
+            TelnetOption(self, 'we-SGA', SGA, WILL, WONT, DO, DONT, REQUESTED),
+            TelnetOption(self, 'they-SGA', SGA, DO, DONT, WILL, WONT, REQUESTED),
+            TelnetOption(self, 'they-BINARY', BINARY, DO, DONT, WILL, WONT, INACTIVE),
+            TelnetOption(self, 'they-RFC2217', COM_PORT_OPTION, DO, DONT, WILL, WONT, REQUESTED),
+        ] + mandadory_options
+        # RFC 2217 specific states
+        # COM port settings
+        self._rfc2217_port_settings = {
+            'baudrate': TelnetSubnegotiation(self, 'baudrate', SET_BAUDRATE, SERVER_SET_BAUDRATE),
+            'datasize': TelnetSubnegotiation(self, 'datasize', SET_DATASIZE, SERVER_SET_DATASIZE),
+            'parity':   TelnetSubnegotiation(self, 'parity',   SET_PARITY,   SERVER_SET_PARITY),
+            'stopsize': TelnetSubnegotiation(self, 'stopsize', SET_STOPSIZE, SERVER_SET_STOPSIZE),
+            }
+        # There are more subnegotiation objects, combine all in one dictionary
+        # for easy access
+        self._rfc2217_options = {
+            'purge':    TelnetSubnegotiation(self, 'purge',    PURGE_DATA,   SERVER_PURGE_DATA),
+            'control':  TelnetSubnegotiation(self, 'control',  SET_CONTROL,  SERVER_SET_CONTROL),
+            }
+        self._rfc2217_options.update(self._rfc2217_port_settings)
+        # cache for line and modem states that the server sends to us
+        self._linestate = 0
+        self._modemstate = None
+        self._modemstate_expires = 0
+        # RFC 2217 flow control between server and client
+        self._remote_suspend_flow = False
+
+        self._thread = threading.Thread(target=self._telnetReadLoop)
+        self._thread.setDaemon(True)
+        self._thread.setName('pySerial RFC 2217 reader thread for %s' % (self._port,))
+        self._thread.start()
+
+        # negotiate Telnet/RFC 2217 -> send initial requests
+        for option in self._telnet_options:
+            if option.state is REQUESTED:
+                self.telnetSendOption(option.send_yes, option.option)
+        # now wait until important options are negotiated
+        timeout_time = time.time() + self._network_timeout
+        while time.time() < timeout_time:
+            time.sleep(0.05)    # prevent 100% CPU load
+            if sum(o.active for o in mandadory_options) == len(mandadory_options):
+                break
+        else:
+            raise SerialException("Remote does not seem to support RFC2217 or BINARY mode %r" % mandadory_options)
+        if self.logger:
+            self.logger.info("Negotiated options: %s" % self._telnet_options)
+
+        # fine, go on, set RFC 2271 specific things
+        self._reconfigurePort()
+        # all things set up get, now a clean start
+        self._isOpen = True
+        if not self._rtscts:
+            self.setRTS(True)
+            self.setDTR(True)
+        self.flushInput()
+        self.flushOutput()
+
+    def _reconfigurePort(self):
+        """Set communication parameters on opened port."""
+        if self._socket is None:
+            raise SerialException("Can only operate on open ports")
+
+        # if self._timeout != 0 and self._interCharTimeout is not None:
+            # XXX
+
+        if self._writeTimeout is not None:
+            raise NotImplementedError('writeTimeout is currently not supported')
+            # XXX
+
+        # Setup the connection
+        # to get good performance, all parameter changes are sent first...
+        if not isinstance(self._baudrate, (int, long)) or not 0 < self._baudrate < 2**32:
+            raise ValueError("invalid baudrate: %r" % (self._baudrate))
+        self._rfc2217_port_settings['baudrate'].set(struct.pack('!I', self._baudrate))
+        self._rfc2217_port_settings['datasize'].set(struct.pack('!B', self._bytesize))
+        self._rfc2217_port_settings['parity'].set(struct.pack('!B', RFC2217_PARITY_MAP[self._parity]))
+        self._rfc2217_port_settings['stopsize'].set(struct.pack('!B', RFC2217_STOPBIT_MAP[self._stopbits]))
+
+        # and now wait until parameters are active
+        items = self._rfc2217_port_settings.values()
+        if self.logger:
+            self.logger.debug("Negotiating settings: %s" % (items,))
+        timeout_time = time.time() + self._network_timeout
+        while time.time() < timeout_time:
+            time.sleep(0.05)    # prevent 100% CPU load
+            if sum(o.active for o in items) == len(items):
+                break
+        else:
+            raise SerialException("Remote does not accept parameter change (RFC2217): %r" % items)
+        if self.logger:
+            self.logger.info("Negotiated settings: %s" % (items,))
+
+        if self._rtscts and self._xonxoff:
+            raise ValueError('xonxoff and rtscts together are not supported')
+        elif self._rtscts:
+            self.rfc2217SetControl(SET_CONTROL_USE_HW_FLOW_CONTROL)
+        elif self._xonxoff:
+            self.rfc2217SetControl(SET_CONTROL_USE_SW_FLOW_CONTROL)
+        else:
+            self.rfc2217SetControl(SET_CONTROL_USE_NO_FLOW_CONTROL)
+
+    def close(self):
+        """Close port"""
+        if self._isOpen:
+            if self._socket:
+                try:
+                    self._socket.shutdown(socket.SHUT_RDWR)
+                    self._socket.close()
+                except:
+                    # ignore errors.
+                    pass
+                self._socket = None
+            if self._thread:
+                self._thread.join()
+            self._isOpen = False
+            # in case of quick reconnects, give the server some time
+            time.sleep(0.3)
+
+    def makeDeviceName(self, port):
+        raise SerialException("there is no sensible way to turn numbers into URLs")
+
+    def fromURL(self, url):
+        """extract host and port from an URL string"""
+        if url.lower().startswith("rfc2217://"): url = url[10:]
+        try:
+            # is there a "path" (our options)?
+            if '/' in url:
+                # cut away options
+                url, options = url.split('/', 1)
+                # process options now, directly altering self
+                for option in options.split('/'):
+                    if '=' in option:
+                        option, value = option.split('=', 1)
+                    else:
+                        value = None
+                    if option == 'logging':
+                        logging.basicConfig()   # XXX is that good to call it here?
+                        self.logger = logging.getLogger('pySerial.rfc2217')
+                        self.logger.setLevel(LOGGER_LEVELS[value])
+                        self.logger.debug('enabled logging')
+                    elif option == 'ign_set_control':
+                        self._ignore_set_control_answer = True
+                    elif option == 'poll_modem':
+                        self._poll_modem_state = True
+                    elif option == 'timeout':
+                        self._network_timeout = float(value)
+                    else:
+                        raise ValueError('unknown option: %r' % (option,))
+            # get host and port
+            host, port = url.split(':', 1) # may raise ValueError because of unpacking
+            port = int(port)               # and this if it's not a number
+            if not 0 <= port < 65536: raise ValueError("port not in range 0...65535")
+        except ValueError, e:
+            raise SerialException('expected a string in the form "[rfc2217://]<host>:<port>[/option[/option...]]": %s' % e)
+        return (host, port)
+
+    #  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
+
+    def inWaiting(self):
+        """Return the number of characters currently in the input buffer."""
+        if not self._isOpen: raise portNotOpenError
+        return self._read_buffer.qsize()
+
+    def read(self, size=1):
+        """\
+        Read size bytes from the serial port. If a timeout is set it may
+        return less characters as requested. With no timeout it will block
+        until the requested number of bytes is read.
+        """
+        if not self._isOpen: raise portNotOpenError
+        data = bytearray()
+        try:
+            while len(data) < size:
+                if self._thread is None:
+                    raise SerialException('connection failed (reader thread died)')
+                data.append(self._read_buffer.get(True, self._timeout))
+        except Queue.Empty: # -> timeout
+            pass
+        return bytes(data)
+
+    def write(self, data):
+        """\
+        Output the given string over the serial port. Can block if the
+        connection is blocked. May raise SerialException if the connection is
+        closed.
+        """
+        if not self._isOpen: raise portNotOpenError
+        self._write_lock.acquire()
+        try:
+            try:
+                self._socket.sendall(to_bytes(data).replace(IAC, IAC_DOUBLED))
+            except socket.error, e:
+                raise SerialException("connection failed (socket error): %s" % e) # XXX what exception if socket connection fails
+        finally:
+            self._write_lock.release()
+        return len(data)
+
+    def flushInput(self):
+        """Clear input buffer, discarding all that is in the buffer."""
+        if not self._isOpen: raise portNotOpenError
+        self.rfc2217SendPurge(PURGE_RECEIVE_BUFFER)
+        # empty read buffer
+        while self._read_buffer.qsize():
+            self._read_buffer.get(False)
+
+    def flushOutput(self):
+        """\
+        Clear output buffer, aborting the current output and
+        discarding all that is in the buffer.
+        """
+        if not self._isOpen: raise portNotOpenError
+        self.rfc2217SendPurge(PURGE_TRANSMIT_BUFFER)
+
+    def sendBreak(self, duration=0.25):
+        """Send break condition. Timed, returns to idle state after given
+        duration."""
+        if not self._isOpen: raise portNotOpenError
+        self.setBreak(True)
+        time.sleep(duration)
+        self.setBreak(False)
+
+    def setBreak(self, level=True):
+        """\
+        Set break: Controls TXD. When active, to transmitting is
+        possible.
+        """
+        if not self._isOpen: raise portNotOpenError
+        if self.logger:
+            self.logger.info('set BREAK to %s' % ('inactive', 'active')[bool(level)])
+        if level:
+            self.rfc2217SetControl(SET_CONTROL_BREAK_ON)
+        else:
+            self.rfc2217SetControl(SET_CONTROL_BREAK_OFF)
+
+    def setRTS(self, level=True):
+        """Set terminal status line: Request To Send."""
+        if not self._isOpen: raise portNotOpenError
+        if self.logger:
+            self.logger.info('set RTS to %s' % ('inactive', 'active')[bool(level)])
+        if level:
+            self.rfc2217SetControl(SET_CONTROL_RTS_ON)
+        else:
+            self.rfc2217SetControl(SET_CONTROL_RTS_OFF)
+
+    def setDTR(self, level=True):
+        """Set terminal status line: Data Terminal Ready."""
+        if not self._isOpen: raise portNotOpenError
+        if self.logger:
+            self.logger.info('set DTR to %s' % ('inactive', 'active')[bool(level)])
+        if level:
+            self.rfc2217SetControl(SET_CONTROL_DTR_ON)
+        else:
+            self.rfc2217SetControl(SET_CONTROL_DTR_OFF)
+
+    def getCTS(self):
+        """Read terminal status line: Clear To Send."""
+        if not self._isOpen: raise portNotOpenError
+        return bool(self.getModemState() & MODEMSTATE_MASK_CTS)
+
+    def getDSR(self):
+        """Read terminal status line: Data Set Ready."""
+        if not self._isOpen: raise portNotOpenError
+        return bool(self.getModemState() & MODEMSTATE_MASK_DSR)
+
+    def getRI(self):
+        """Read terminal status line: Ring Indicator."""
+        if not self._isOpen: raise portNotOpenError
+        return bool(self.getModemState() & MODEMSTATE_MASK_RI)
+
+    def getCD(self):
+        """Read terminal status line: Carrier Detect."""
+        if not self._isOpen: raise portNotOpenError
+        return bool(self.getModemState() & MODEMSTATE_MASK_CD)
+
+    # - - - platform specific - - -
+    # None so far
+
+    # - - - RFC2217 specific - - -
+
+    def _telnetReadLoop(self):
+        """read loop for the socket."""
+        mode = M_NORMAL
+        suboption = None
+        try:
+            while self._socket is not None:
+                try:
+                    data = self._socket.recv(1024)
+                except socket.timeout:
+                    # just need to get out of recv form time to time to check if
+                    # still alive
+                    continue
+                except socket.error, e:
+                    # connection fails -> terminate loop
+                    if self.logger:
+                        self.logger.debug("socket error in reader thread: %s" % (e,))
+                    break
+                if not data: break # lost connection
+                for byte in data:
+                    if mode == M_NORMAL:
+                        # interpret as command or as data
+                        if byte == IAC:
+                            mode = M_IAC_SEEN
+                        else:
+                            # store data in read buffer or sub option buffer
+                            # depending on state
+                            if suboption is not None:
+                                suboption.append(byte)
+                            else:
+                                self._read_buffer.put(byte)
+                    elif mode == M_IAC_SEEN:
+                        if byte == IAC:
+                            # interpret as command doubled -> insert character
+                            # itself
+                            if suboption is not None:
+                                suboption.append(IAC)
+                            else:
+                                self._read_buffer.put(IAC)
+                            mode = M_NORMAL
+                        elif byte == SB:
+                            # sub option start
+                            suboption = bytearray()
+                            mode = M_NORMAL
+                        elif byte == SE:
+                            # sub option end -> process it now
+                            self._telnetProcessSubnegotiation(bytes(suboption))
+                            suboption = None
+                            mode = M_NORMAL
+                        elif byte in (DO, DONT, WILL, WONT):
+                            # negotiation
+                            telnet_command = byte
+                            mode = M_NEGOTIATE
+                        else:
+                            # other telnet commands
+                            self._telnetProcessCommand(byte)
+                            mode = M_NORMAL
+                    elif mode == M_NEGOTIATE: # DO, DONT, WILL, WONT was received, option now following
+                        self._telnetNegotiateOption(telnet_command, byte)
+                        mode = M_NORMAL
+        finally:
+            self._thread = None
+            if self.logger:
+                self.logger.debug("read thread terminated")
+
+    # - incoming telnet commands and options
+
+    def _telnetProcessCommand(self, command):
+        """Process commands other than DO, DONT, WILL, WONT."""
+        # Currently none. RFC2217 only uses negotiation and subnegotiation.
+        if self.logger:
+            self.logger.warning("ignoring Telnet command: %r" % (command,))
+
+    def _telnetNegotiateOption(self, command, option):
+        """Process incoming DO, DONT, WILL, WONT."""
+        # check our registered telnet options and forward command to them
+        # they know themselves if they have to answer or not
+        known = False
+        for item in self._telnet_options:
+            # can have more than one match! as some options are duplicated for
+            # 'us' and 'them'
+            if item.option == option:
+                item.process_incoming(command)
+                known = True
+        if not known:
+            # handle unknown options
+            # only answer to positive requests and deny them
+            if command == WILL or command == DO:
+                self.telnetSendOption((command == WILL and DONT or WONT), option)
+                if self.logger:
+                    self.logger.warning("rejected Telnet option: %r" % (option,))
+
+
+    def _telnetProcessSubnegotiation(self, suboption):
+        """Process subnegotiation, the data between IAC SB and IAC SE."""
+        if suboption[0:1] == COM_PORT_OPTION:
+            if suboption[1:2] == SERVER_NOTIFY_LINESTATE and len(suboption) >= 3:
+                self._linestate = ord(suboption[2:3]) # ensure it is a number
+                if self.logger:
+                    self.logger.info("NOTIFY_LINESTATE: %s" % self._linestate)
+            elif suboption[1:2] == SERVER_NOTIFY_MODEMSTATE and len(suboption) >= 3:
+                self._modemstate = ord(suboption[2:3]) # ensure it is a number
+                if self.logger:
+                    self.logger.info("NOTIFY_MODEMSTATE: %s" % self._modemstate)
+                # update time when we think that a poll would make sense
+                self._modemstate_expires = time.time() + 0.3
+            elif suboption[1:2] == FLOWCONTROL_SUSPEND:
+                self._remote_suspend_flow = True
+            elif suboption[1:2] == FLOWCONTROL_RESUME:
+                self._remote_suspend_flow = False
+            else:
+                for item in self._rfc2217_options.values():
+                    if item.ack_option == suboption[1:2]:
+                        #~ print "processing COM_PORT_OPTION: %r" % list(suboption[1:])
+                        item.checkAnswer(bytes(suboption[2:]))
+                        break
+                else:
+                    if self.logger:
+                        self.logger.warning("ignoring COM_PORT_OPTION: %r" % (suboption,))
+        else:
+            if self.logger:
+                self.logger.warning("ignoring subnegotiation: %r" % (suboption,))
+
+    # - outgoing telnet commands and options
+
+    def _internal_raw_write(self, data):
+        """internal socket write with no data escaping. used to send telnet stuff."""
+        self._write_lock.acquire()
+        try:
+            self._socket.sendall(data)
+        finally:
+            self._write_lock.release()
+
+    def telnetSendOption(self, action, option):
+        """Send DO, DONT, WILL, WONT."""
+        self._internal_raw_write(to_bytes([IAC, action, option]))
+
+    def rfc2217SendSubnegotiation(self, option, value=''):
+        """Subnegotiation of RFC2217 parameters."""
+        value = value.replace(IAC, IAC_DOUBLED)
+        self._internal_raw_write(to_bytes([IAC, SB, COM_PORT_OPTION, option] + list(value) + [IAC, SE]))
+
+    def rfc2217SendPurge(self, value):
+        item = self._rfc2217_options['purge']
+        item.set(value) # transmit desired purge type
+        item.wait(self._network_timeout) # wait for acknowledge from the server
+
+    def rfc2217SetControl(self, value):
+        item = self._rfc2217_options['control']
+        item.set(value) # transmit desired control type
+        if self._ignore_set_control_answer:
+            # answers are ignored when option is set. compatibility mode for
+            # servers that answer, but not the expected one... (or no answer
+            # at all) i.e. sredird
+            time.sleep(0.1)  # this helps getting the unit tests passed
+        else:
+            item.wait(self._network_timeout)  # wait for acknowledge from the server
+
+    def rfc2217FlowServerReady(self):
+        """\
+        check if server is ready to receive data. block for some time when
+        not.
+        """
+        #~ if self._remote_suspend_flow:
+            #~ wait---
+
+    def getModemState(self):
+        """\
+        get last modem state (cached value. if value is "old", request a new
+        one. this cache helps that we don't issue to many requests when e.g. all
+        status lines, one after the other is queried by te user (getCTS, getDSR
+        etc.)
+        """
+        # active modem state polling enabled? is the value fresh enough?
+        if self._poll_modem_state and self._modemstate_expires < time.time():
+            if self.logger:
+                self.logger.debug('polling modem state')
+            # when it is older, request an update
+            self.rfc2217SendSubnegotiation(NOTIFY_MODEMSTATE)
+            timeout_time = time.time() + self._network_timeout
+            while time.time() < timeout_time:
+                time.sleep(0.05)    # prevent 100% CPU load
+                # when expiration time is updated, it means that there is a new
+                # value
+                if self._modemstate_expires > time.time():
+                    if self.logger:
+                        self.logger.warning('poll for modem state failed')
+                    break
+            # even when there is a timeout, do not generate an error just
+            # return the last known value. this way we can support buggy
+            # servers that do not respond to polls, but send automatic
+            # updates.
+        if self._modemstate is not None:
+            if self.logger:
+                self.logger.debug('using cached modem state')
+            return self._modemstate
+        else:
+            # never received a notification from the server
+            raise SerialException("remote sends no NOTIFY_MODEMSTATE")
+
+
+# assemble Serial class with the platform specific implementation and the base
+# for file-like behavior. for Python 2.6 and newer, that provide the new I/O
+# library, derive from io.RawIOBase
+try:
+    import io
+except ImportError:
+    # classic version with our own file-like emulation
+    class Serial(RFC2217Serial, FileLike):
+        pass
+else:
+    # io library present
+    class Serial(RFC2217Serial, io.RawIOBase):
+        pass
+
+
+#############################################################################
+# The following is code that helps implementing an RFC 2217 server.
+
+class PortManager(object):
+    """\
+    This class manages the state of Telnet and RFC 2217. It needs a serial
+    instance and a connection to work with. Connection is expected to implement
+    a (thread safe) write function, that writes the string to the network.
+    """
+
+    def __init__(self, serial_port, connection, logger=None):
+        self.serial = serial_port
+        self.connection = connection
+        self.logger = logger
+        self._client_is_rfc2217 = False
+
+        # filter state machine
+        self.mode = M_NORMAL
+        self.suboption = None
+        self.telnet_command = None
+
+        # states for modem/line control events
+        self.modemstate_mask = 255
+        self.last_modemstate = None
+        self.linstate_mask = 0
+
+        # all supported telnet options
+        self._telnet_options = [
+            TelnetOption(self, 'ECHO', ECHO, WILL, WONT, DO, DONT, REQUESTED),
+            TelnetOption(self, 'we-SGA', SGA, WILL, WONT, DO, DONT, REQUESTED),
+            TelnetOption(self, 'they-SGA', SGA, DO, DONT, WILL, WONT, INACTIVE),
+            TelnetOption(self, 'we-BINARY', BINARY, WILL, WONT, DO, DONT, INACTIVE),
+            TelnetOption(self, 'they-BINARY', BINARY, DO, DONT, WILL, WONT, REQUESTED),
+            TelnetOption(self, 'we-RFC2217', COM_PORT_OPTION, WILL, WONT, DO, DONT, REQUESTED, self._client_ok),
+            TelnetOption(self, 'they-RFC2217', COM_PORT_OPTION, DO, DONT, WILL, WONT, INACTIVE, self._client_ok),
+            ]
+
+        # negotiate Telnet/RFC2217 -> send initial requests
+        if self.logger:
+            self.logger.debug("requesting initial Telnet/RFC 2217 options")
+        for option in self._telnet_options:
+            if option.state is REQUESTED:
+                self.telnetSendOption(option.send_yes, option.option)
+        # issue 1st modem state notification
+
+    def _client_ok(self):
+        """\
+        callback of telnet option. it gets called when option is activated.
+        this one here is used to detect when the client agrees on RFC 2217. a
+        flag is set so that other functions like check_modem_lines know if the
+        client is ok.
+        """
+        # The callback is used for we and they so if one party agrees, we're
+        # already happy. it seems not all servers do the negotiation correctly
+        # and i guess there are incorrect clients too.. so be happy if client
+        # answers one or the other positively.
+        self._client_is_rfc2217 = True
+        if self.logger:
+            self.logger.info("client accepts RFC 2217")
+        # this is to ensure that the client gets a notification, even if there
+        # was no change
+        self.check_modem_lines(force_notification=True)
+
+    # - outgoing telnet commands and options
+
+    def telnetSendOption(self, action, option):
+        """Send DO, DONT, WILL, WONT."""
+        self.connection.write(to_bytes([IAC, action, option]))
+
+    def rfc2217SendSubnegotiation(self, option, value=''):
+        """Subnegotiation of RFC 2217 parameters."""
+        value = value.replace(IAC, IAC_DOUBLED)
+        self.connection.write(to_bytes([IAC, SB, COM_PORT_OPTION, option] + list(value) + [IAC, SE]))
+
+    # - check modem lines, needs to be called periodically from user to
+    # establish polling
+
+    def check_modem_lines(self, force_notification=False):
+        modemstate = (
+            (self.serial.getCTS() and MODEMSTATE_MASK_CTS) |
+            (self.serial.getDSR() and MODEMSTATE_MASK_DSR) |
+            (self.serial.getRI() and MODEMSTATE_MASK_RI) |
+            (self.serial.getCD() and MODEMSTATE_MASK_CD)
+        )
+        # check what has changed
+        deltas = modemstate ^ (self.last_modemstate or 0) # when last is None -> 0
+        if deltas & MODEMSTATE_MASK_CTS:
+            modemstate |= MODEMSTATE_MASK_CTS_CHANGE
+        if deltas & MODEMSTATE_MASK_DSR:
+            modemstate |= MODEMSTATE_MASK_DSR_CHANGE
+        if deltas & MODEMSTATE_MASK_RI:
+            modemstate |= MODEMSTATE_MASK_RI_CHANGE
+        if deltas & MODEMSTATE_MASK_CD:
+            modemstate |= MODEMSTATE_MASK_CD_CHANGE
+        # if new state is different and the mask allows this change, send
+        # notification. suppress notifications when client is not rfc2217
+        if modemstate != self.last_modemstate or force_notification:
+            if (self._client_is_rfc2217 and (modemstate & self.modemstate_mask)) or force_notification:
+                self.rfc2217SendSubnegotiation(
+                    SERVER_NOTIFY_MODEMSTATE,
+                    to_bytes([modemstate & self.modemstate_mask])
+                    )
+                if self.logger:
+                    self.logger.info("NOTIFY_MODEMSTATE: %s" % (modemstate,))
+            # save last state, but forget about deltas.
+            # otherwise it would also notify about changing deltas which is
+            # probably not very useful
+            self.last_modemstate = modemstate & 0xf0
+
+    # - outgoing data escaping
+
+    def escape(self, data):
+        """\
+        this generator function is for the user. all outgoing data has to be
+        properly escaped, so that no IAC character in the data stream messes up
+        the Telnet state machine in the server.
+
+        socket.sendall(escape(data))
+        """
+        for byte in data:
+            if byte == IAC:
+                yield IAC
+                yield IAC
+            else:
+                yield byte
+
+    # - incoming data filter
+
+    def filter(self, data):
+        """\
+        handle a bunch of incoming bytes. this is a generator. it will yield
+        all characters not of interest for Telnet/RFC 2217.
+
+        The idea is that the reader thread pushes data from the socket through
+        this filter:
+
+        for byte in filter(socket.recv(1024)):
+            # do things like CR/LF conversion/whatever
+            # and write data to the serial port
+            serial.write(byte)
+
+        (socket error handling code left as exercise for the reader)
+        """
+        for byte in data:
+            if self.mode == M_NORMAL:
+                # interpret as command or as data
+                if byte == IAC:
+                    self.mode = M_IAC_SEEN
+                else:
+                    # store data in sub option buffer or pass it to our
+                    # consumer depending on state
+                    if self.suboption is not None:
+                        self.suboption.append(byte)
+                    else:
+                        yield byte
+            elif self.mode == M_IAC_SEEN:
+                if byte == IAC:
+                    # interpret as command doubled -> insert character
+                    # itself
+                    if self.suboption is not None:
+                        self.suboption.append(byte)
+                    else:
+                        yield byte
+                    self.mode = M_NORMAL
+                elif byte == SB:
+                    # sub option start
+                    self.suboption = bytearray()
+                    self.mode = M_NORMAL
+                elif byte == SE:
+                    # sub option end -> process it now
+                    self._telnetProcessSubnegotiation(bytes(self.suboption))
+                    self.suboption = None
+                    self.mode = M_NORMAL
+                elif byte in (DO, DONT, WILL, WONT):
+                    # negotiation
+                    self.telnet_command = byte
+                    self.mode = M_NEGOTIATE
+                else:
+                    # other telnet commands
+                    self._telnetProcessCommand(byte)
+                    self.mode = M_NORMAL
+            elif self.mode == M_NEGOTIATE: # DO, DONT, WILL, WONT was received, option now following
+                self._telnetNegotiateOption(self.telnet_command, byte)
+                self.mode = M_NORMAL
+
+    # - incoming telnet commands and options
+
+    def _telnetProcessCommand(self, command):
+        """Process commands other than DO, DONT, WILL, WONT."""
+        # Currently none. RFC2217 only uses negotiation and subnegotiation.
+        if self.logger:
+            self.logger.warning("ignoring Telnet command: %r" % (command,))
+
+    def _telnetNegotiateOption(self, command, option):
+        """Process incoming DO, DONT, WILL, WONT."""
+        # check our registered telnet options and forward command to them
+        # they know themselves if they have to answer or not
+        known = False
+        for item in self._telnet_options:
+            # can have more than one match! as some options are duplicated for
+            # 'us' and 'them'
+            if item.option == option:
+                item.process_incoming(command)
+                known = True
+        if not known:
+            # handle unknown options
+            # only answer to positive requests and deny them
+            if command == WILL or command == DO:
+                self.telnetSendOption((command == WILL and DONT or WONT), option)
+                if self.logger:
+                    self.logger.warning("rejected Telnet option: %r" % (option,))
+
+
+    def _telnetProcessSubnegotiation(self, suboption):
+        """Process subnegotiation, the data between IAC SB and IAC SE."""
+        if suboption[0:1] == COM_PORT_OPTION:
+            if self.logger:
+                self.logger.debug('received COM_PORT_OPTION: %r' % (suboption,))
+            if suboption[1:2] == SET_BAUDRATE:
+                backup = self.serial.baudrate
+                try:
+                    (baudrate,) = struct.unpack("!I", suboption[2:6])
+                    if baudrate != 0:
+                        self.serial.baudrate = baudrate
+                except ValueError, e:
+                    if self.logger:
+                        self.logger.error("failed to set baud rate: %s" % (e,))
+                    self.serial.baudrate = backup
+                else:
+                    if self.logger:
+                        self.logger.info("%s baud rate: %s" % (baudrate and 'set' or 'get', self.serial.baudrate))
+                self.rfc2217SendSubnegotiation(SERVER_SET_BAUDRATE, struct.pack("!I", self.serial.baudrate))
+            elif suboption[1:2] == SET_DATASIZE:
+                backup = self.serial.bytesize
+                try:
+                    (datasize,) = struct.unpack("!B", suboption[2:3])
+                    if datasize != 0:
+                        self.serial.bytesize = datasize
+                except ValueError, e:
+                    if self.logger:
+                        self.logger.error("failed to set data size: %s" % (e,))
+                    self.serial.bytesize = backup
+                else:
+                    if self.logger:
+                        self.logger.info("%s data size: %s" % (datasize and 'set' or 'get', self.serial.bytesize))
+                self.rfc2217SendSubnegotiation(SERVER_SET_DATASIZE, struct.pack("!B", self.serial.bytesize))
+            elif suboption[1:2] == SET_PARITY:
+                backup = self.serial.parity
+                try:
+                    parity = struct.unpack("!B", suboption[2:3])[0]
+                    if parity != 0:
+                            self.serial.parity = RFC2217_REVERSE_PARITY_MAP[parity]
+                except ValueError, e:
+                    if self.logger:
+                        self.logger.error("failed to set parity: %s" % (e,))
+                    self.serial.parity = backup
+                else:
+                    if self.logger:
+                        self.logger.info("%s parity: %s" % (parity and 'set' or 'get', self.serial.parity))
+                self.rfc2217SendSubnegotiation(
+                    SERVER_SET_PARITY,
+                    struct.pack("!B", RFC2217_PARITY_MAP[self.serial.parity])
+                    )
+            elif suboption[1:2] == SET_STOPSIZE:
+                backup = self.serial.stopbits
+                try:
+                    stopbits = struct.unpack("!B", suboption[2:3])[0]
+                    if stopbits != 0:
+                        self.serial.stopbits = RFC2217_REVERSE_STOPBIT_MAP[stopbits]
+                except ValueError, e:
+                    if self.logger:
+                        self.logger.error("failed to set stop bits: %s" % (e,))
+                    self.serial.stopbits = backup
+                else:
+                    if self.logger:
+                        self.logger.info("%s stop bits: %s" % (stopbits and 'set' or 'get', self.serial.stopbits))
+                self.rfc2217SendSubnegotiation(
+                    SERVER_SET_STOPSIZE,
+                    struct.pack("!B", RFC2217_STOPBIT_MAP[self.serial.stopbits])
+                    )
+            elif suboption[1:2] == SET_CONTROL:
+                if suboption[2:3] == SET_CONTROL_REQ_FLOW_SETTING:
+                    if self.serial.xonxoff:
+                        self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_SW_FLOW_CONTROL)
+                    elif self.serial.rtscts:
+                        self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_HW_FLOW_CONTROL)
+                    else:
+                        self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_NO_FLOW_CONTROL)
+                elif suboption[2:3] == SET_CONTROL_USE_NO_FLOW_CONTROL:
+                    self.serial.xonxoff = False
+                    self.serial.rtscts = False
+                    if self.logger:
+                        self.logger.info("changed flow control to None")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_NO_FLOW_CONTROL)
+                elif suboption[2:3] == SET_CONTROL_USE_SW_FLOW_CONTROL:
+                    self.serial.xonxoff = True
+                    if self.logger:
+                        self.logger.info("changed flow control to XON/XOFF")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_SW_FLOW_CONTROL)
+                elif suboption[2:3] == SET_CONTROL_USE_HW_FLOW_CONTROL:
+                    self.serial.rtscts = True
+                    if self.logger:
+                        self.logger.info("changed flow control to RTS/CTS")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_USE_HW_FLOW_CONTROL)
+                elif suboption[2:3] == SET_CONTROL_REQ_BREAK_STATE:
+                    if self.logger:
+                        self.logger.warning("requested break state - not implemented")
+                    pass # XXX needs cached value
+                elif suboption[2:3] == SET_CONTROL_BREAK_ON:
+                    self.serial.setBreak(True)
+                    if self.logger:
+                        self.logger.info("changed BREAK to active")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_BREAK_ON)
+                elif suboption[2:3] == SET_CONTROL_BREAK_OFF:
+                    self.serial.setBreak(False)
+                    if self.logger:
+                        self.logger.info("changed BREAK to inactive")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_BREAK_OFF)
+                elif suboption[2:3] == SET_CONTROL_REQ_DTR:
+                    if self.logger:
+                        self.logger.warning("requested DTR state - not implemented")
+                    pass # XXX needs cached value
+                elif suboption[2:3] == SET_CONTROL_DTR_ON:
+                    self.serial.setDTR(True)
+                    if self.logger:
+                        self.logger.info("changed DTR to active")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_DTR_ON)
+                elif suboption[2:3] == SET_CONTROL_DTR_OFF:
+                    self.serial.setDTR(False)
+                    if self.logger:
+                        self.logger.info("changed DTR to inactive")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_DTR_OFF)
+                elif suboption[2:3] == SET_CONTROL_REQ_RTS:
+                    if self.logger:
+                        self.logger.warning("requested RTS state - not implemented")
+                    pass # XXX needs cached value
+                    #~ self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_RTS_ON)
+                elif suboption[2:3] == SET_CONTROL_RTS_ON:
+                    self.serial.setRTS(True)
+                    if self.logger:
+                        self.logger.info("changed RTS to active")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_RTS_ON)
+                elif suboption[2:3] == SET_CONTROL_RTS_OFF:
+                    self.serial.setRTS(False)
+                    if self.logger:
+                        self.logger.info("changed RTS to inactive")
+                    self.rfc2217SendSubnegotiation(SERVER_SET_CONTROL, SET_CONTROL_RTS_OFF)
+                #~ elif suboption[2:3] == SET_CONTROL_REQ_FLOW_SETTING_IN:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_NO_FLOW_CONTROL_IN:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_SW_FLOW_CONTOL_IN:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_HW_FLOW_CONTOL_IN:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_DCD_FLOW_CONTROL:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_DTR_FLOW_CONTROL:
+                #~ elif suboption[2:3] == SET_CONTROL_USE_DSR_FLOW_CONTROL:
+            elif suboption[1:2] == NOTIFY_LINESTATE:
+                # client polls for current state
+                self.rfc2217SendSubnegotiation(
+                    SERVER_NOTIFY_LINESTATE,
+                    to_bytes([0])   # sorry, nothing like that implemented
+                    )
+            elif suboption[1:2] == NOTIFY_MODEMSTATE:
+                if self.logger:
+                    self.logger.info("request for modem state")
+                # client polls for current state
+                self.check_modem_lines(force_notification=True)
+            elif suboption[1:2] == FLOWCONTROL_SUSPEND:
+                if self.logger:
+                    self.logger.info("suspend")
+                self._remote_suspend_flow = True
+            elif suboption[1:2] == FLOWCONTROL_RESUME:
+                if self.logger:
+                    self.logger.info("resume")
+                self._remote_suspend_flow = False
+            elif suboption[1:2] == SET_LINESTATE_MASK:
+                self.linstate_mask = ord(suboption[2:3]) # ensure it is a number
+                if self.logger:
+                    self.logger.info("line state mask: 0x%02x" % (self.linstate_mask,))
+            elif suboption[1:2] == SET_MODEMSTATE_MASK:
+                self.modemstate_mask = ord(suboption[2:3]) # ensure it is a number
+                if self.logger:
+                    self.logger.info("modem state mask: 0x%02x" % (self.modemstate_mask,))
+            elif suboption[1:2] == PURGE_DATA:
+                if suboption[2:3] == PURGE_RECEIVE_BUFFER:
+                    self.serial.flushInput()
+                    if self.logger:
+                        self.logger.info("purge in")
+                    self.rfc2217SendSubnegotiation(SERVER_PURGE_DATA, PURGE_RECEIVE_BUFFER)
+                elif suboption[2:3] == PURGE_TRANSMIT_BUFFER:
+                    self.serial.flushOutput()
+                    if self.logger:
+                        self.logger.info("purge out")
+                    self.rfc2217SendSubnegotiation(SERVER_PURGE_DATA, PURGE_TRANSMIT_BUFFER)
+                elif suboption[2:3] == PURGE_BOTH_BUFFERS:
+                    self.serial.flushInput()
+                    self.serial.flushOutput()
+                    if self.logger:
+                        self.logger.info("purge both")
+                    self.rfc2217SendSubnegotiation(SERVER_PURGE_DATA, PURGE_BOTH_BUFFERS)
+                else:
+                    if self.logger:
+                        self.logger.error("undefined PURGE_DATA: %r" % list(suboption[2:]))
+            else:
+                if self.logger:
+                    self.logger.error("undefined COM_PORT_OPTION: %r" % list(suboption[1:]))
+        else:
+            if self.logger:
+                self.logger.warning("unknown subnegotiation: %r" % (suboption,))
+
+
+# simple client test
+if __name__ == '__main__':
+    import sys
+    s = Serial('rfc2217://localhost:7000', 115200)
+    sys.stdout.write('%s\n' % s)
+
+    #~ s.baudrate = 1898
+
+    sys.stdout.write("write...\n")
+    s.write("hello\n")
+    s.flush()
+    sys.stdout.write("read: %s\n" % s.read(5))
+
+    #~ s.baudrate = 19200
+    #~ s.databits = 7
+    s.close()