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# nxt.backend.socket module -- Socket backend
# Copyright (C) 2011 zonedaobne, Marcus Wanner
# Copyright (C) 2021 Nicolas Schodet
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
import logging
import socket
import nxt.brick
logger = logging.getLogger(__name__)
class SocketSock:
"""Socket socket connected to a NXT brick."""
#: Block size, conservative.
bsize = 60
def __init__(self, host, port):
self._host = host
self._port = port
self._sock = None
#: Connection type, used to evaluate latency, known on connection.
self.type = None
def __str__(self):
return f"Socket ({self._host}:{self._port})"
def connect(self):
"""Connect to NXT brick.
:return: Connected brick.
:rtype: Brick
"""
logger.info("connecting via %s:%d", self._host, self._port)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((self._host, self._port))
self._sock = sock
self.send(bytes((0x98,)))
self.type = "ip" + self.recv().decode("ascii")
return nxt.brick.Brick(self)
def close(self):
"""Close the connection."""
if self._sock is not None:
logger.info("closing connection to %s:%d", self._host, self._port)
self._sock.send(bytes((0x99,)))
self._sock.close()
self._sock = None
self.type = None
def send(self, data):
"""Send raw data.
:param bytes data: Data to send.
"""
logger.debug("send: %s", data.hex())
self._sock.send(data)
def recv(self):
"""Receive raw data.
:return: Received data.
:rtype: bytes
"""
data = self._sock.recv(1024)
logger.debug("recv: %s", data.hex())
return data
class Backend:
"""Socket backend.
To be used with ``nxt-server`` script to access a NXT brick over the network.
"""
def find(self, server_host="localhost", server_port=2727, **kwargs):
"""Find bricks connected using a socket.
:param str server_host: Server address or name, default to `localhost`.
:param server_port: Server port, default to 2727.
:type server_port: str or int
:param kwargs: Other parameters are ignored.
:return: Iterator over all found bricks.
:rtype: Iterator[Brick]
"""
sock = SocketSock(server_host, int(server_port))
try:
brick = sock.connect()
except ConnectionRefusedError:
logger.exception("failed to connect to device %s", sock)
else:
yield brick
def get_backend():
"""Get an instance of the Socket backend.
:return: Socket backend.
:rtype: Backend
"""
return Backend()
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