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#! python
#
# This module implements a simple socket based client.
# It does not support changing any port parameters and will silently ignore any
# requests to do so.
#
# The purpose of this module is that applications using pySerial can connect to
# TCP/IP to serial port converters that do not support RFC 2217.
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# (C) 2001-2015 Chris Liechti <cliechti@gmx.net>
#
# SPDX-License-Identifier: BSD-3-Clause
#
# URL format: socket://<host>:<port>[/option[/option...]]
# options:
# - "debug" print diagnostic messages
import errno
import logging
import select
import socket
import time
try:
import urlparse
except ImportError:
import urllib.parse as urlparse
from serial.serialutil import SerialBase, SerialException, to_bytes, \
portNotOpenError, writeTimeoutError, Timeout
# map log level names to constants. used in from_url()
LOGGER_LEVELS = {
'debug': logging.DEBUG,
'info': logging.INFO,
'warning': logging.WARNING,
'error': logging.ERROR,
}
POLL_TIMEOUT = 5
class Serial(SerialBase):
"""Serial port implementation for plain sockets."""
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
if self._port is None:
raise SerialException("Port must be configured before it can be used.")
if self.is_open:
raise SerialException("Port is already open.")
try:
# timeout is used for write timeout support :/ and to get an initial connection timeout
self._socket = socket.create_connection(self.from_url(self.portstr), timeout=POLL_TIMEOUT)
except Exception as msg:
self._socket = None
raise SerialException("Could not open port {}: {}".format(self.portstr, msg))
# after connecting, switch to non-blocking, we're using select
self._socket.setblocking(False)
# not that there is anything to configure...
self._reconfigure_port()
# all things set up get, now a clean start
self.is_open = True
if not self._dsrdtr:
self._update_dtr_state()
if not self._rtscts:
self._update_rts_state()
self.reset_input_buffer()
self.reset_output_buffer()
def _reconfigure_port(self):
"""\
Set communication parameters on opened port. For the socket://
protocol all settings are ignored!
"""
if self._socket is None:
raise SerialException("Can only operate on open ports")
if self.logger:
self.logger.info('ignored port configuration change')
def close(self):
"""Close port"""
if self.is_open:
if self._socket:
try:
self._socket.shutdown(socket.SHUT_RDWR)
self._socket.close()
except:
# ignore errors.
pass
self._socket = None
self.is_open = False
# in case of quick reconnects, give the server some time
time.sleep(0.3)
def from_url(self, url):
"""extract host and port from an URL string"""
parts = urlparse.urlsplit(url)
if parts.scheme != "socket":
raise SerialException(
'expected a string in the form '
'"socket://<host>:<port>[?logging={debug|info|warning|error}]": '
'not starting with socket:// ({!r})'.format(parts.scheme))
try:
# process options now, directly altering self
for option, values in urlparse.parse_qs(parts.query, True).items():
if option == 'logging':
logging.basicConfig() # XXX is that good to call it here?
self.logger = logging.getLogger('pySerial.socket')
self.logger.setLevel(LOGGER_LEVELS[values[0]])
self.logger.debug('enabled logging')
else:
raise ValueError('unknown option: {!r}'.format(option))
if not 0 <= parts.port < 65536:
raise ValueError("port not in range 0...65535")
except ValueError as e:
raise SerialException(
'expected a string in the form '
'"socket://<host>:<port>[?logging={debug|info|warning|error}]": {}'.format(e))
return (parts.hostname, parts.port)
# - - - - - - - - - - - - - - - - - - - - - - - -
@property
def in_waiting(self):
"""Return the number of bytes currently in the input buffer."""
if not self.is_open:
raise portNotOpenError
# Poll the socket to see if it is ready for reading.
# If ready, at least one byte will be to read.
lr, lw, lx = select.select([self._socket], [], [], 0)
return len(lr)
# select based implementation, similar to posix, but only using socket API
# to be portable, additionally handle socket timeout which is used to
# emulate write timeouts
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.is_open:
raise portNotOpenError
read = bytearray()
timeout = Timeout(self._timeout)
while len(read) < size:
try:
ready, _, _ = select.select([self._socket], [], [], timeout.time_left())
# If select was used with a timeout, and the timeout occurs, it
# returns with empty lists -> thus abort read operation.
# For timeout == 0 (non-blocking operation) also abort when
# there is nothing to read.
if not ready:
break # timeout
buf = self._socket.recv(size - len(read))
# read should always return some data as select reported it was
# ready to read when we get to this point, unless it is EOF
if not buf:
raise SerialException('socket disconnected')
read.extend(buf)
except OSError as e:
# this is for Python 3.x where select.error is a subclass of
# OSError ignore BlockingIOErrors and EINTR. other errors are shown
# https://www.python.org/dev/peps/pep-0475.
if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
except (select.error, socket.error) as e:
# this is for Python 2.x
# ignore BlockingIOErrors and EINTR. all errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
if timeout.expired():
break
return bytes(read)
def write(self, data):
"""\
Output the given byte string over the serial port. Can block if the
connection is blocked. May raise SerialException if the connection is
closed.
"""
if not self.is_open:
raise portNotOpenError
d = to_bytes(data)
tx_len = length = len(d)
timeout = Timeout(self._write_timeout)
while tx_len > 0:
try:
n = self._socket.send(d)
if timeout.is_non_blocking:
# Zero timeout indicates non-blocking - simply return the
# number of bytes of data actually written
return n
elif not timeout.is_infinite:
# when timeout is set, use select to wait for being ready
# with the time left as timeout
if timeout.expired():
raise writeTimeoutError
_, ready, _ = select.select([], [self._socket], [], timeout.time_left())
if not ready:
raise writeTimeoutError
else:
assert timeout.time_left() is None
# wait for write operation
_, ready, _ = select.select([], [self._socket], [], None)
if not ready:
raise SerialException('write failed (select)')
d = d[n:]
tx_len -= n
except SerialException:
raise
except OSError as e:
# this is for Python 3.x where select.error is a subclass of
# OSError ignore BlockingIOErrors and EINTR. other errors are shown
# https://www.python.org/dev/peps/pep-0475.
if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('write failed: {}'.format(e))
except select.error as e:
# this is for Python 2.x
# ignore BlockingIOErrors and EINTR. all errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('write failed: {}'.format(e))
if not timeout.is_non_blocking and timeout.expired():
raise writeTimeoutError
return length - len(d)
def reset_input_buffer(self):
"""Clear input buffer, discarding all that is in the buffer."""
if not self.is_open:
raise portNotOpenError
# just use recv to remove input, while there is some
ready = True
while ready:
ready, _, _ = select.select([self._socket], [], [], 0)
try:
self._socket.recv(4096)
except OSError as e:
# this is for Python 3.x where select.error is a subclass of
# OSError ignore BlockingIOErrors and EINTR. other errors are shown
# https://www.python.org/dev/peps/pep-0475.
if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
except (select.error, socket.error) as e:
# this is for Python 2.x
# ignore BlockingIOErrors and EINTR. all errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
def reset_output_buffer(self):
"""\
Clear output buffer, aborting the current output and
discarding all that is in the buffer.
"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('ignored reset_output_buffer')
def send_break(self, duration=0.25):
"""\
Send break condition. Timed, returns to idle state after given
duration.
"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('ignored send_break({!r})'.format(duration))
def _update_break_state(self):
"""Set break: Controls TXD. When active, to transmitting is
possible."""
if self.logger:
self.logger.info('ignored _update_break_state({!r})'.format(self._break_state))
def _update_rts_state(self):
"""Set terminal status line: Request To Send"""
if self.logger:
self.logger.info('ignored _update_rts_state({!r})'.format(self._rts_state))
def _update_dtr_state(self):
"""Set terminal status line: Data Terminal Ready"""
if self.logger:
self.logger.info('ignored _update_dtr_state({!r})'.format(self._dtr_state))
@property
def cts(self):
"""Read terminal status line: Clear To Send"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for cts')
return True
@property
def dsr(self):
"""Read terminal status line: Data Set Ready"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for dsr')
return True
@property
def ri(self):
"""Read terminal status line: Ring Indicator"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for ri')
return False
@property
def cd(self):
"""Read terminal status line: Carrier Detect"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for cd)')
return True
# - - - platform specific - - -
# works on Linux and probably all the other POSIX systems
def fileno(self):
"""Get the file handle of the underlying socket for use with select"""
return self._socket.fileno()
#
# simple client test
if __name__ == '__main__':
import sys
s = Serial('socket://localhost:7000')
sys.stdout.write('{}\n'.format(s))
sys.stdout.write("write...\n")
s.write(b"hello\n")
s.flush()
sys.stdout.write("read: {}\n".format(s.read(5)))
s.close()
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