python OscScreenGrabLAN.py png|bmp|csv oscilloscope_IP

OscScreenGrabLAN.py

#!/usr/bin/env python3
"""Take screen captures from DS1000Z-series oscilloscopes

This program captures either the waveform or the whole screen of a Rigol
DS1000Z series oscilloscope, then saves it on the computer as a CSV, PNG
or BMP file.

The program uses the LXI protocol, so the computer must have a LAN
connection with the oscilloscope.
"""

from enum import Enum, auto
import argparse
import logging
import os
import platform
import subprocess
import sys
import time

from Rigol_functions import *
from telnetlib_receive_all import Telnet

__version__ = 'v1.1.0'
# Added TMC Blockheader decoding
# Added possibility to manually allow run for scopes other then DS1000Z
__author__ = 'RoGeorge'

#
# TODO: Write all SCPI commands in their short name, with capitals
# TODO: Add ignore instrument model switch instead of asking
#
# TODO: Detect if the scope is in RUN or in STOP mode (looking at the length of data extracted)
# TODO: Add logic for 1200/mdep points to avoid displaying the 'Invalid Input!' message
# TODO: Add message for csv data points: mdep (all) or 1200 (screen), depending on RUN/STOP state, MATH and WAV:MODE
# TODO: Add STOP scope switch
#
# TODO: Add debug switch
# TODO: Clarify info, warning, error, debug and print messages
#
# TODO: Add automated version increase
#
# TODO: Extract all memory datapoints. For the moment, CSV is limited to the displayed 1200 datapoints.
# TODO: Use arrays instead of strings and lists for csv mode.
#
# TODO: variables/functions name refactoring
# TODO: Fine tune maximum chunk size request
# TODO: Investigate scaling. Sometimes 3.0e-008 instead of expected 3.0e-000
# TODO: Add timestamp and mark the trigger point as t0
# TODO: Use channels label instead of chan1, chan2, chan3, chan4, math
# TODO: Add command line parameters file path
# TODO: Speed-up the transfer, try to replace Telnet with direct TCP
# TODO: Add GUI
# TODO: Add browse and custom filename selection
# TODO: Create executable distributions
#

# Set the desired logging level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
logging.basicConfig(level=logging.INFO,
                    format='%(asctime)s - %(levelname)s - %(message)s',
                    filename=os.path.basename(sys.argv[0]) + '.log',
                    filemode='w')

logging.info("***** New run started...")
logging.info("OS Platform: " + str(platform.uname()))
log_running_python_versions()

# Update the next lines for your own default settings:
path_to_save = "captures/"
IP_DS1104Z = "192.168.1.3"

# Rigol/LXI specific constants
port = 5555

big_wait = 10
smallWait = 1

company = 0
model = 1
serial = 2


# Read/verify file type
class FileType(Enum):
    png = auto()
    bmp = auto()
    csv = auto()


# Check network response (ping)
def test_ping(hostname):
    """Ping hostname once"""
    if platform.system() == "Windows":
        command = ['ping', '-n', '1', hostname]
    else:
        command = ['ping', '-c', '1', hostname]
    completed = subprocess.run(command, stdout=subprocess.DEVNULL,
                   stderr=subprocess.DEVNULL)

    if completed.returncode != 0:
        print()
        print("WARNING! No response pinging", hostname)
        print("Check network cables and settings.")
        print("You should be able to ping the oscilloscope.")

def run(hostname, filename, filetype):
    test_ping(hostname)

    # Open a modified telnet session
    # The default telnetlib drops 0x00 characters,
    #   so a modified library 'telnetlib_receive_all' is used instead
    tn = Telnet(hostname, port)
    instrument_id = command(tn, "*IDN?").decode()    # ask for instrument ID

    # Check if instrument is set to accept LAN commands
    if instrument_id == "command error":
        print ("Instrument reply:", instrument_id)
        print ("Check the oscilloscope settings.")
        print ("Utility -> IO Setting -> RemoteIO -> LAN must be ON")
        sys.exit("ERROR")

    # Check if instrument is indeed a Rigol DS1000Z series
    id_fields = instrument_id.split(",")
    if (id_fields[company] != "RIGOL TECHNOLOGIES") or \
            (id_fields[model][:3] != "DS1") or (id_fields[model][-1] != "Z"):
        print ("Found instrument model '{}' from '{}'".format(id_fields[model], id_fields[company]))
        print ("WARNING: No Rigol from series DS1000Z found at", hostname)
        print ()
        typed = raw_input("ARE YOU SURE YOU WANT TO CONTINUE? (No/Yes):")
        if typed != 'Yes':
            sys.exit('Nothing done. Bye!')

    print ("Instrument ID:", instrument_id)

    # Prepare filename as C:\MODEL_SERIAL_YYYY-MM-DD_HH.MM.SS
    timestamp = time.strftime("%Y-%m-%d_%H.%M.%S", time.localtime())
    if filename is None:
        filename = "{}{}_{}_{}.{}".format(path_to_save, id_fields[model],
                                          id_fields[serial], timestamp,
                                          filetype.name)

    if filetype in {FileType.png, FileType.bmp}:
        # Ask for an oscilloscope display print screen
        print ("Receiving screen capture...")

        if filetype is FileType.png:
            buff = command(tn, ":DISP:DATA? ON,OFF,PNG")
        else:
            buff = command(tn, ":DISP:DATA? ON,OFF,BMP8")

        expectedBuffLen = expected_buff_bytes(buff)
        # Just in case the transfer did not complete in the expected time, read the remaining 'buff' chunks
        while len(buff) < expectedBuffLen:
            logging.warning("Received LESS data then expected! (" +
                            str(len(buff)) + " out of " + str(expectedBuffLen) + " expected 'buff' bytes.)")
            tmp = tn.read_until(b"\n", smallWait)
            if len(tmp) == 0:
                break
            buff += tmp
            logging.warning(str(len(tmp)) + " leftover bytes added to 'buff'.")

        if len(buff) < expectedBuffLen:
            logging.error("After reading all data chunks, 'buff' is still shorter then expected! (" +
                          str(len(buff)) + " out of " + str(expectedBuffLen) + " expected 'buff' bytes.)")
            sys.exit("ERROR")

        # Strip TMC Blockheader and keep only the data
        tmcHeaderLen = tmc_header_bytes(buff)
        expectedDataLen = expected_data_bytes(buff)
        buff = buff[tmcHeaderLen: tmcHeaderLen+expectedDataLen]

        # Write raw data to file
        with open(filename, 'wb') as f:
            f.write(buff)
        print('Saved raw data to {}'.format(filename))

    # TODO: Change WAV:FORM from ASC to BYTE
    elif filetype is FileType.csv:
        # Put the scope in STOP mode - for the moment, deal with it by manually stopping the scope
        # TODO: Add command line switch and code logic for 1200 vs ALL memory data points
        # tn.write("stop")
        # response = tn.read_until("\n", 1)

        # Scan for displayed channels
        chanList = []
        for channel in ["CHAN1", "CHAN2", "CHAN3", "CHAN4", "MATH"]:
            response = command(tn, ":" + channel + ":DISP?")

            # If channel is active
            if response == '1\n':
                chanList += [channel]

        # the meaning of 'max' is   - will read only the displayed data when the scope is in RUN mode,
        #                             or when the MATH channel is selected
        #                           - will read all the acquired data points when the scope is in STOP mode
        # TODO: Change mode to MAX
        # TODO: Add command line switch for MAX/NORM
        command(tn, ":WAV:MODE NORM")
        command(tn, ":WAV:STAR 0")
        command(tn, ":WAV:MODE NORM")

        csv_buff = ""

        # for each active channel
        for channel in chanList:
            print ()

            # Set WAVE parameters
            command(tn, ":WAV:SOUR " + channel)
            command(tn, ":WAV:FORM ASC")

            # MATH channel does not allow START and STOP to be set. They are always 0 and 1200
            if channel != "MATH":
                command(tn, ":WAV:STAR 1")
                command(tn, ":WAV:STOP 1200")

            buff = ""
            print ("Data from channel '" + str(channel) + "', points " + str(1) + "-" + str(1200) + ": Receiving...")
            buffChunk = command(tn, ":WAV:DATA?")

            # Just in case the transfer did not complete in the expected time
            while buffChunk[-1] != "\n":
                logging.warning("The data transfer did not complete in the expected time of " +
                                str(smallWait) + " second(s).")

                tmp = tn.read_until(b"\n", smallWait)
                if len(tmp) == 0:
                    break
                buffChunk += tmp
                logging.warning(str(len(tmp)) + " leftover bytes added to 'buff_chunks'.")

            # Append data chunks
            # Strip TMC Blockheader and terminator bytes
            buff += buffChunk[tmc_header_bytes(buffChunk):-1] + ","

            # Strip the last \n char
            buff = buff[:-1]

            # Process data
            buff_list = buff.split(",")
            buff_rows = len(buff_list)

            # Put read data into csv_buff
            csv_buff_list = csv_buff.split(os.linesep)
            csv_rows = len(csv_buff_list)

            current_row = 0
            if csv_buff == "":
                csv_first_column = True
                csv_buff = str(channel) + os.linesep
            else:
                csv_first_column = False
                csv_buff = str(csv_buff_list[current_row]) + "," + str(channel) + os.linesep

            for point in buff_list:
                current_row += 1
                if csv_first_column:
                    csv_buff += str(point) + os.linesep
                else:
                    if current_row < csv_rows:
                        csv_buff += str(csv_buff_list[current_row]) + "," + str(point) + os.linesep
                    else:
                        csv_buff += "," + str(point) + os.linesep

        # Save data as CSV
        scr_file = open(filename, "wb")
        scr_file.write(csv_buff)
        scr_file.close()

        print ("Saved file:", "'" + filename + "'")

    tn.close()

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Take screen captures from"
            " DS1000Z-series oscilloscopes")
    parser.add_argument("-t", "--type",
            choices=FileType.__members__,
            help="Optional type of file to save")
    parser.add_argument("hostname",
            help="Hostname or IP address of the oscilloscope")
    parser.add_argument("filename", nargs="?",
            help="Optional name of output file")

    args = parser.parse_args()

    # If no type is specified, auto-detect from the filename
    if args.type is None:
        if args.filename is None:
            parser.error("Either a file type or a filename must be specified")
        args.type = os.path.splitext(args.filename)[1][1:]

    try:
        args.type = FileType[args.type]
    except KeyError:
        parser.error("Unknown file type: {}".format(args.type))

    run(args.hostname, args.filename, args.type)

Rigol_functions.py

import pip
import sys
import logging

__author__ = 'RoGeorge'


def log_running_python_versions():
    logging.info("Python version: " + str(sys.version) + ", " + str(sys.version_info))  # () required in Python 3.

    installed_packages = pip.get_installed_distributions()
    installed_packages_list = sorted(["%s==%s" % (i.key, i.version) for i in installed_packages])
    logging.info("Installed Python modules: " + str(installed_packages_list))


def command(tn, scpi):
    logging.info("SCPI to be sent: " + scpi)
    answer_wait_s = 1
    response = ""
    while response != b"1\n":
        tn.write("*OPC?\n")  # previous operation(s) has completed ?
        logging.info("Send SCPI: *OPC? # May I send a command? 1==yes")
        response = tn.read_until(b"\n", 1)  # wait max 1s for an answer
        logging.info("Received response!")

    tn.write(scpi + "\n")
    logging.info("Sent SCPI: " + scpi)
    response = tn.read_until(b"\n", answer_wait_s)
    logging.info("Received response!")
    return response


# first TMC byte is '#'
# second is '0'..'9', and tells how many of the next ASCII chars
#   should be converted into an integer.
#   The integer will be the length of the data stream (in bytes)
# after all the data bytes, the last char is '\n'
def tmc_header_bytes(buff):
    return 2 + int(buff[1:2])


def expected_data_bytes(buff):
    return int(buff[2:tmc_header_bytes(buff)])


def expected_buff_bytes(buff):
    return tmc_header_bytes(buff) + expected_data_bytes(buff) + 1


def get_memory_depth(tn):
    # Define number of horizontal grid divisions for DS1054Z
    h_grid = 12

    # ACQuire:MDEPth
    mdep = command(tn, ":ACQ:MDEP?")

    # if mdep is "AUTO"
    if mdep == "AUTO\n":
        # ACQuire:SRATe
        srate = command(tn, ":ACQ:SRAT?")

        # TIMebase[:MAIN]:SCALe
        scal = command(tn, ":TIM:SCAL?")

        # mdep = h_grid * scal * srate
        mdep = h_grid * float(scal) * float(srate)

    # return mdep
    return int(mdep)

telnetlib_receive_all.py

# This whole file is a copy of the 'telnetlib.py' that came with Python 2.7.12 distribution.
# A patch was applied to this file, in order to stop dropping null (0x00) characters.

r"""TELNET client class.

Based on RFC 854: TELNET Protocol Specification, by J. Postel and
J. Reynolds

Example:

>>> from telnetlib import Telnet
>>> tn = Telnet('www.python.org', 79)   # connect to finger port
>>> tn.write('guido\r\n')
>>> print (tn.read_all())
Login       Name               TTY         Idle    When    Where
guido    Guido van Rossum      pts/2        <Dec  2 11:10> snag.cnri.reston..

>>>

Note that read_all() won't read until eof -- it just reads some data
-- but it guarantees to read at least one byte unless EOF is hit.

It is possible to pass a Telnet object to select.select() in order to
wait until more data is available.  Note that in this case,
read_eager() may return '' even if there was data on the socket,
because the protocol negotiation may have eaten the data.  This is why
EOFError is needed in some cases to distinguish between "no data" and
"connection closed" (since the socket also appears ready for reading
when it is closed).

To do:
- option negotiation
- timeout should be intrinsic to the connection object instead of an
  option on one of the read calls only

"""


# Imported modules
import errno
import sys
import socket
import select

__all__ = ["Telnet"]

# Tunable parameters
DEBUGLEVEL = 0

# Telnet protocol defaults
TELNET_PORT = 23

# Telnet protocol characters (don't change)
IAC  = chr(255) # "Interpret As Command"
DONT = chr(254)
DO   = chr(253)
WONT = chr(252)
WILL = chr(251)
theNULL = chr(0)

SE  = chr(240)  # Subnegotiation End
NOP = chr(241)  # No Operation
DM  = chr(242)  # Data Mark
BRK = chr(243)  # Break
IP  = chr(244)  # Interrupt process
AO  = chr(245)  # Abort output
AYT = chr(246)  # Are You There
EC  = chr(247)  # Erase Character
EL  = chr(248)  # Erase Line
GA  = chr(249)  # Go Ahead
SB =  chr(250)  # Subnegotiation Begin


# Telnet protocol options code (don't change)
# These ones all come from arpa/telnet.h
BINARY = chr(0) # 8-bit data path
ECHO = chr(1) # echo
RCP = chr(2) # prepare to reconnect
SGA = chr(3) # suppress go ahead
NAMS = chr(4) # approximate message size
STATUS = chr(5) # give status
TM = chr(6) # timing mark
RCTE = chr(7) # remote controlled transmission and echo
NAOL = chr(8) # negotiate about output line width
NAOP = chr(9) # negotiate about output page size
NAOCRD = chr(10) # negotiate about CR disposition
NAOHTS = chr(11) # negotiate about horizontal tabstops
NAOHTD = chr(12) # negotiate about horizontal tab disposition
NAOFFD = chr(13) # negotiate about formfeed disposition
NAOVTS = chr(14) # negotiate about vertical tab stops
NAOVTD = chr(15) # negotiate about vertical tab disposition
NAOLFD = chr(16) # negotiate about output LF disposition
XASCII = chr(17) # extended ascii character set
LOGOUT = chr(18) # force logout
BM = chr(19) # byte macro
DET = chr(20) # data entry terminal
SUPDUP = chr(21) # supdup protocol
SUPDUPOUTPUT = chr(22) # supdup output
SNDLOC = chr(23) # send location
TTYPE = chr(24) # terminal type
EOR = chr(25) # end or record
TUID = chr(26) # TACACS user identification
OUTMRK = chr(27) # output marking
TTYLOC = chr(28) # terminal location number
VT3270REGIME = chr(29) # 3270 regime
X3PAD = chr(30) # X.3 PAD
NAWS = chr(31) # window size
TSPEED = chr(32) # terminal speed
LFLOW = chr(33) # remote flow control
LINEMODE = chr(34) # Linemode option
XDISPLOC = chr(35) # X Display Location
OLD_ENVIRON = chr(36) # Old - Environment variables
AUTHENTICATION = chr(37) # Authenticate
ENCRYPT = chr(38) # Encryption option
NEW_ENVIRON = chr(39) # New - Environment variables
# the following ones come from
# http://www.iana.org/assignments/telnet-options
# Unfortunately, that document does not assign identifiers
# to all of them, so we are making them up
TN3270E = chr(40) # TN3270E
XAUTH = chr(41) # XAUTH
CHARSET = chr(42) # CHARSET
RSP = chr(43) # Telnet Remote Serial Port
COM_PORT_OPTION = chr(44) # Com Port Control Option
SUPPRESS_LOCAL_ECHO = chr(45) # Telnet Suppress Local Echo
TLS = chr(46) # Telnet Start TLS
KERMIT = chr(47) # KERMIT
SEND_URL = chr(48) # SEND-URL
FORWARD_X = chr(49) # FORWARD_X
PRAGMA_LOGON = chr(138) # TELOPT PRAGMA LOGON
SSPI_LOGON = chr(139) # TELOPT SSPI LOGON
PRAGMA_HEARTBEAT = chr(140) # TELOPT PRAGMA HEARTBEAT
EXOPL = chr(255) # Extended-Options-List
NOOPT = chr(0)

class Telnet:

    """Telnet interface class.

    An instance of this class represents a connection to a telnet
    server.  The instance is initially not connected; the open()
    method must be used to establish a connection.  Alternatively, the
    host name and optional port number can be passed to the
    constructor, too.

    Don't try to reopen an already connected instance.

    This class has many read_*() methods.  Note that some of them
    raise EOFError when the end of the connection is read, because
    they can return an empty string for other reasons.  See the
    individual doc strings.

    read_until(expected, [timeout])
        Read until the expected string has been seen, or a timeout is
        hit (default is no timeout); may block.

    read_all()
        Read all data until EOF; may block.

    read_some()
        Read at least one byte or EOF; may block.

    read_very_eager()
        Read all data available already queued or on the socket,
        without blocking.

    read_eager()
        Read either data already queued or some data available on the
        socket, without blocking.

    read_lazy()
        Read all data in the raw queue (processing it first), without
        doing any socket I/O.

    read_very_lazy()
        Reads all data in the cooked queue, without doing any socket
        I/O.

    read_sb_data()
        Reads available data between SB ... SE sequence. Don't block.

    set_option_negotiation_callback(callback)
        Each time a telnet option is read on the input flow, this callback
        (if set) is called with the following parameters :
        callback(telnet socket, command, option)
            option will be chr(0) when there is no option.
        No other action is done afterwards by telnetlib.

    """

    def __init__(self, host=None, port=0,
                 timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
        """Constructor.

        When called without arguments, create an unconnected instance.
        With a hostname argument, it connects the instance; port number
        and timeout are optional.
        """
        self.debuglevel = DEBUGLEVEL
        self.host = host
        self.port = port
        self.timeout = timeout
        self.sock = None
        self.rawq = b''
        self.irawq = 0
        self.cookedq = b''
        self.eof = 0
        self.iacseq = b'' # Buffer for IAC sequence.
        self.sb = 0 # flag for SB and SE sequence.
        self.sbdataq = b''
        self.option_callback = None
        self._has_poll = hasattr(select, 'poll')
        if host is not None:
            self.open(host, port, timeout)

    def open(self, host, port=0, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
        """Connect to a host.

        The optional second argument is the port number, which
        defaults to the standard telnet port (23).

        Don't try to reopen an already connected instance.
        """
        self.eof = 0
        if not port:
            port = TELNET_PORT
        self.host = host
        self.port = port
        self.timeout = timeout
        self.sock = socket.create_connection((host, port), timeout)

    def __del__(self):
        """Destructor -- close the connection."""
        self.close()

    def msg(self, msg, *args):
        """Print a debug message, when the debug level is > 0.

        If extra arguments are present, they are substituted in the
        message using the standard string formatting operator.

        """
        if self.debuglevel > 0:
            print ('Telnet(%s,%s):' % (self.host, self.port),)
            if args:
                print (msg % args)
            else:
                print (msg)

    def set_debuglevel(self, debuglevel):
        """Set the debug level.

        The higher it is, the more debug output you get (on sys.stdout).

        """
        self.debuglevel = debuglevel

    def close(self):
        """Close the connection."""
        sock = self.sock
        self.sock = 0
        self.eof = 1
        self.iacseq = b''
        self.sb = 0
        if sock:
            sock.close()

    def get_socket(self):
        """Return the socket object used internally."""
        return self.sock

    def fileno(self):
        """Return the fileno() of the socket object used internally."""
        return self.sock.fileno()

    def write(self, buffer):
        """Write a string to the socket, doubling any IAC characters.

        Can block if the connection is blocked.  May raise
        socket.error if the connection is closed.

        """
        if IAC in buffer:
            buffer = buffer.replace(IAC, IAC+IAC)
        self.msg("send %r", buffer)
        self.sock.sendall(bytes(buffer, 'ascii'))

    def read_until(self, match, timeout=None):
        """Read until a given string is encountered or until timeout.

        When no match is found, return whatever is available instead,
        possibly the empty string.  Raise EOFError if the connection
        is closed and no cooked data is available.

        """
        if self._has_poll:
            return self._read_until_with_poll(match, timeout)
        else:
            return self._read_until_with_select(match, timeout)

    def _read_until_with_poll(self, match, timeout):
        """Read until a given string is encountered or until timeout.

        This method uses select.poll() to implement the timeout.
        """
        n = len(match)
        call_timeout = timeout
        if timeout is not None:
            from time import time
            time_start = time()
        self.process_rawq()
        i = self.cookedq.find(match)
        if i < 0:
            poller = select.poll()
            poll_in_or_priority_flags = select.POLLIN | select.POLLPRI
            poller.register(self, poll_in_or_priority_flags)
            while i < 0 and not self.eof:
                try:
                    # Poll takes its timeout in milliseconds.
                    ready = poller.poll(None if timeout is None
                                        else 1000 * call_timeout)
                except select.error as e:
                    if e.errno == errno.EINTR:
                        if timeout is not None:
                            elapsed = time() - time_start
                            call_timeout = timeout-elapsed
                        continue
                    raise
                for fd, mode in ready:
                    if mode & poll_in_or_priority_flags:
                        i = max(0, len(self.cookedq)-n)
                        self.fill_rawq()
                        self.process_rawq()
                        i = self.cookedq.find(match, i)
                if timeout is not None:
                    elapsed = time() - time_start
                    if elapsed >= timeout:
                        break
                    call_timeout = timeout-elapsed
            poller.unregister(self)
        if i >= 0:
            i = i + n
            buf = self.cookedq[:i]
            self.cookedq = self.cookedq[i:]
            return buf
        return self.read_very_lazy()

    def _read_until_with_select(self, match, timeout=None):
        """Read until a given string is encountered or until timeout.

        The timeout is implemented using select.select().
        """
        n = len(match)
        self.process_rawq()
        i = self.cookedq.find(match)
        if i >= 0:
            i = i+n
            buf = self.cookedq[:i]
            self.cookedq = self.cookedq[i:]
            return buf
        s_reply = ([self], [], [])
        s_args = s_reply
        if timeout is not None:
            s_args = s_args + (timeout,)
            from time import time
            time_start = time()
        while not self.eof and select.select(*s_args) == s_reply:
            i = max(0, len(self.cookedq)-n)
            self.fill_rawq()
            self.process_rawq()
            i = self.cookedq.find(match, i)
            if i >= 0:
                i = i+n
                buf = self.cookedq[:i]
                self.cookedq = self.cookedq[i:]
                return buf
            if timeout is not None:
                elapsed = time() - time_start
                if elapsed >= timeout:
                    break
                s_args = s_reply + (timeout-elapsed,)
        return self.read_very_lazy()

    def read_all(self):
        """Read all data until EOF; block until connection closed."""
        self.process_rawq()
        while not self.eof:
            self.fill_rawq()
            self.process_rawq()
        buf = self.cookedq
        self.cookedq = b''
        return buf

    def read_some(self):
        """Read at least one byte of cooked data unless EOF is hit.

        Return '' if EOF is hit.  Block if no data is immediately
        available.

        """
        self.process_rawq()
        while not self.cookedq and not self.eof:
            self.fill_rawq()
            self.process_rawq()
        buf = self.cookedq
        self.cookedq = b''
        return buf

    def read_very_eager(self):
        """Read everything that's possible without blocking in I/O (eager).

        Raise EOFError if connection closed and no cooked data
        available.  Return '' if no cooked data available otherwise.
        Don't block unless in the midst of an IAC sequence.

        """
        self.process_rawq()
        while not self.eof and self.sock_avail():
            self.fill_rawq()
            self.process_rawq()
        return self.read_very_lazy()

    def read_eager(self):
        """Read readily available data.

        Raise EOFError if connection closed and no cooked data
        available.  Return '' if no cooked data available otherwise.
        Don't block unless in the midst of an IAC sequence.

        """
        self.process_rawq()
        while not self.cookedq and not self.eof and self.sock_avail():
            self.fill_rawq()
            self.process_rawq()
        return self.read_very_lazy()

    def read_lazy(self):
        """Process and return data that's already in the queues (lazy).

        Raise EOFError if connection closed and no data available.
        Return '' if no cooked data available otherwise.  Don't block
        unless in the midst of an IAC sequence.

        """
        self.process_rawq()
        return self.read_very_lazy()

    def read_very_lazy(self):
        """Return any data available in the cooked queue (very lazy).

        Raise EOFError if connection closed and no data available.
        Return '' if no cooked data available otherwise.  Don't block.

        """
        buf = self.cookedq
        self.cookedq = b''
        if not buf and self.eof and not self.rawq:
            raise EOFError ('telnet connection closed')
        return buf

    def read_sb_data(self):
        """Return any data available in the SB ... SE queue.

        Return '' if no SB ... SE available. Should only be called
        after seeing a SB or SE command. When a new SB command is
        found, old unread SB data will be discarded. Don't block.

        """
        buf = self.sbdataq
        self.sbdataq = b''
        return buf

    def set_option_negotiation_callback(self, callback):
        """Provide a callback function called after each receipt of a telnet option."""
        self.option_callback = callback

    def process_rawq(self):
        """Transfer from raw queue to cooked queue.

        Set self.eof when connection is closed.  Don't block unless in
        the midst of an IAC sequence.

        """
        buf = [b'', b'']
        try:
            while self.rawq:
                c = self.rawq_getchar()
                if not self.iacseq:
                    #if c == theNULL:
                    #    continue
                    #if c == "\021":
                    #    continue
                    if c != IAC:
                        buf[self.sb] = buf[self.sb] + c
                        continue
                    else:
                        self.iacseq += c
                elif len(self.iacseq) == 1:
                    # 'IAC: IAC CMD [OPTION only for WILL/WONT/DO/DONT]'
                    if c in (DO, DONT, WILL, WONT):
                        self.iacseq += c
                        continue

                    self.iacseq = b''
                    if c == IAC:
                        buf[self.sb] = buf[self.sb] + c
                    else:
                        if c == SB: # SB ... SE start.
                            self.sb = 1
                            self.sbdataq = b''
                        elif c == SE:
                            self.sb = 0
                            self.sbdataq = self.sbdataq + buf[1]
                            buf[1] = b''
                        if self.option_callback:
                            # Callback is supposed to look into
                            # the sbdataq
                            self.option_callback(self.sock, c, NOOPT)
                        else:
                            # We can't offer automatic processing of
                            # suboptions. Alas, we should not get any
                            # unless we did a WILL/DO before.
                            self.msg('IAC %d not recognized' % ord(c))
                elif len(self.iacseq) == 2:
                    cmd = self.iacseq[1]
                    self.iacseq = b''
                    opt = c
                    if cmd in (DO, DONT):
                        self.msg('IAC %s %d',
                            cmd == DO and 'DO' or 'DONT', ord(opt))
                        if self.option_callback:
                            self.option_callback(self.sock, cmd, opt)
                        else:
                            self.sock.sendall(bytes(IAC + WONT + opt, 'ascii'))
                    elif cmd in (WILL, WONT):
                        self.msg('IAC %s %d',
                            cmd == WILL and 'WILL' or 'WONT', ord(opt))
                        if self.option_callback:
                            self.option_callback(self.sock, cmd, opt)
                        else:
                            self.sock.sendall(bytes(IAC + DONT + opt, 'ascii'))
        except EOFError: # raised by self.rawq_getchar()
            self.iacseq = b'' # Reset on EOF
            self.sb = 0
            pass
        self.cookedq = self.cookedq + buf[0]
        self.sbdataq = self.sbdataq + buf[1]

    def rawq_getchar(self):
        """Get next char from raw queue.

        Block if no data is immediately available.  Raise EOFError
        when connection is closed.

        """
        if not self.rawq:
            self.fill_rawq()
            if self.eof:
                raise EOFError
        c = self.rawq[self.irawq:self.irawq+1]
        self.irawq = self.irawq + 1
        if self.irawq >= len(self.rawq):
            self.rawq = b''
            self.irawq = 0
        return c

    def fill_rawq(self):
        """Fill raw queue from exactly one recv() system call.

        Block if no data is immediately available.  Set self.eof when
        connection is closed.

        """
        if self.irawq >= len(self.rawq):
            self.rawq = b''
            self.irawq = 0
        # The buffer size should be fairly small so as to avoid quadratic
        # behavior in process_rawq() above
        buf = self.sock.recv(50)
        self.msg("recv %r", buf)
        self.eof = (not buf)
        self.rawq = self.rawq + buf

    def sock_avail(self):
        """Test whether data is available on the socket."""
        return select.select([self], [], [], 0) == ([self], [], [])

    def interact(self):
        """Interaction function, emulates a very dumb telnet client."""
        if sys.platform == "win32":
            self.mt_interact()
            return
        while 1:
            rfd, wfd, xfd = select.select([self, sys.stdin], [], [])
            if self in rfd:
                try:
                    text = self.read_eager()
                except EOFError:
                    print ('*** Connection closed by remote host ***')
                    break
                if text:
                    sys.stdout.write(text)
                    sys.stdout.flush()
            if sys.stdin in rfd:
                line = sys.stdin.readline()
                if not line:
                    break
                self.write(line)

    def mt_interact(self):
        """Multithreaded version of interact()."""
        import thread
        thread.start_new_thread(self.listener, ())
        while 1:
            line = sys.stdin.readline()
            if not line:
                break
            self.write(line)

    def listener(self):
        """Helper for mt_interact() -- this executes in the other thread."""
        while 1:
            try:
                data = self.read_eager()
            except EOFError:
                print ('*** Connection closed by remote host ***')
                return
            if data:
                sys.stdout.write(data)
            else:
                sys.stdout.flush()

    def expect(self, list, timeout=None):
        """Read until one from a list of a regular expressions matches.

        The first argument is a list of regular expressions, either
        compiled (re.RegexObject instances) or uncompiled (strings).
        The optional second argument is a timeout, in seconds; default
        is no timeout.

        Return a tuple of three items: the index in the list of the
        first regular expression that matches; the match object
        returned; and the text read up till and including the match.

        If EOF is read and no text was read, raise EOFError.
        Otherwise, when nothing matches, return (-1, None, text) where
        text is the text received so far (may be the empty string if a
        timeout happened).

        If a regular expression ends with a greedy match (e.g. '.*')
        or if more than one expression can match the same input, the
        results are undeterministic, and may depend on the I/O timing.

        """
        if self._has_poll:
            return self._expect_with_poll(list, timeout)
        else:
            return self._expect_with_select(list, timeout)

    def _expect_with_poll(self, expect_list, timeout=None):
        """Read until one from a list of a regular expressions matches.

        This method uses select.poll() to implement the timeout.
        """
        re = None
        expect_list = expect_list[:]
        indices = range(len(expect_list))
        for i in indices:
            if not hasattr(expect_list[i], "search"):
                if not re: import re
                expect_list[i] = re.compile(expect_list[i])
        call_timeout = timeout
        if timeout is not None:
            from time import time
            time_start = time()
        self.process_rawq()
        m = None
        for i in indices:
            m = expect_list[i].search(self.cookedq)
            if m:
                e = m.end()
                text = self.cookedq[:e]
                self.cookedq = self.cookedq[e:]
                break
        if not m:
            poller = select.poll()
            poll_in_or_priority_flags = select.POLLIN | select.POLLPRI
            poller.register(self, poll_in_or_priority_flags)
            while not m and not self.eof:
                try:
                    ready = poller.poll(None if timeout is None
                                        else 1000 * call_timeout)
                except select.error as e:
                    if e.errno == errno.EINTR:
                        if timeout is not None:
                            elapsed = time() - time_start
                            call_timeout = timeout-elapsed
                        continue
                    raise
                for fd, mode in ready:
                    if mode & poll_in_or_priority_flags:
                        self.fill_rawq()
                        self.process_rawq()
                        for i in indices:
                            m = expect_list[i].search(self.cookedq)
                            if m:
                                e = m.end()
                                text = self.cookedq[:e]
                                self.cookedq = self.cookedq[e:]
                                break
                if timeout is not None:
                    elapsed = time() - time_start
                    if elapsed >= timeout:
                        break
                    call_timeout = timeout-elapsed
            poller.unregister(self)
        if m:
            return (i, m, text)
        text = self.read_very_lazy()
        if not text and self.eof:
            raise EOFError
        return (-1, None, text)

    def _expect_with_select(self, list, timeout=None):
        """Read until one from a list of a regular expressions matches.

        The timeout is implemented using select.select().
        """
        re = None
        list = list[:]
        indices = range(len(list))
        for i in indices:
            if not hasattr(list[i], "search"):
                if not re: import re
                list[i] = re.compile(list[i])
        if timeout is not None:
            from time import time
            time_start = time()
        while 1:
            self.process_rawq()
            for i in indices:
                m = list[i].search(self.cookedq)
                if m:
                    e = m.end()
                    text = self.cookedq[:e]
                    self.cookedq = self.cookedq[e:]
                    return (i, m, text)
            if self.eof:
                break
            if timeout is not None:
                elapsed = time() - time_start
                if elapsed >= timeout:
                    break
                s_args = ([self.fileno()], [], [], timeout-elapsed)
                r, w, x = select.select(*s_args)
                if not r:
                    break
            self.fill_rawq()
        text = self.read_very_lazy()
        if not text and self.eof:
            raise EOFError
        return (-1, None, text)


def test():
    """Test program for telnetlib.

    Usage: python telnetlib.py [-d] ... [host [port]]

    Default host is localhost; default port is 23.

    """
    debuglevel = 0
    while sys.argv[1:] and sys.argv[1] == '-d':
        debuglevel = debuglevel+1
        del sys.argv[1]
    host = 'localhost'
    if sys.argv[1:]:
        host = sys.argv[1]
    port = 0
    if sys.argv[2:]:
        portstr = sys.argv[2]
        try:
            port = int(portstr)
        except ValueError:
            port = socket.getservbyname(portstr, 'tcp')
    tn = Telnet()
    tn.set_debuglevel(debuglevel)
    tn.open(host, port, timeout=0.5)
    tn.interact()
    tn.close()

if __name__ == '__main__':
    test()