mirror of https://github.com/akuker/RASCSI.git
101 lines
3.5 KiB
Python
101 lines
3.5 KiB
Python
"""
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Module for sending and receiving data over a socket connection with the RaSCSI backend
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"""
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import logging
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from time import sleep
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from flask import abort
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from flask_babel import _
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def send_pb_command(payload):
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"""
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Takes a (str) containing a serialized protobuf as argument.
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Establishes a socket connection with RaSCSI.
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"""
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# Host and port number where rascsi is listening for socket connections
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host = 'localhost'
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port = 6868
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counter = 0
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tries = 20
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error_msg = ""
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import socket
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while counter < tries:
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try:
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with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
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sock.connect((host, port))
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return send_over_socket(sock, payload)
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except socket.error as error:
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counter += 1
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logging.warning("The RaSCSI service is not responding - attempt %s/%s",
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str(counter), str(tries))
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error_msg = str(error)
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sleep(0.2)
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logging.error(error_msg)
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# After failing all attempts, throw a 404 error
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abort(404, _(
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u"The RaSCSI Web Interface failed to connect to RaSCSI at %(host)s:%(port)s "
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u"with error: %(error_msg)s. The RaSCSI process is not running or may have crashed.",
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host=host, port=port, error_msg=error_msg,
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)
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)
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def send_over_socket(sock, payload):
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"""
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Takes a socket object and (str) payload with serialized protobuf.
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Sends payload to RaSCSI over socket and captures the response.
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Tries to extract and interpret the protobuf header to get response size.
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Reads data from socket in 2048 bytes chunks until all data is received.
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"""
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from struct import pack, unpack
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# Sending the magic word "RASCSI" to authenticate with the server
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sock.send(b"RASCSI")
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# Prepending a little endian 32bit header with the message size
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sock.send(pack("<i", len(payload)))
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sock.send(payload)
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# Receive the first 4 bytes to get the response header
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response = sock.recv(4)
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if len(response) >= 4:
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# Extracting the response header to get the length of the response message
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response_length = unpack("<i", response)[0]
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# Reading in chunks, to handle a case where the response message is very large
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chunks = []
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bytes_recvd = 0
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while bytes_recvd < response_length:
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chunk = sock.recv(min(response_length - bytes_recvd, 2048))
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if chunk == b'':
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logging.error(
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"Read an empty chunk from the socket. "
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"Socket connection has dropped unexpectedly. "
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"RaSCSI may have crashed."
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)
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abort(
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503, _(
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u"The RaSCSI Web Interface lost connection to RaSCSI. "
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u"Please go back and try again. "
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u"If the issue persists, please report a bug."
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)
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)
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chunks.append(chunk)
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bytes_recvd = bytes_recvd + len(chunk)
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response_message = b''.join(chunks)
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return response_message
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logging.error(
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"The response from RaSCSI did not contain a protobuf header. "
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"RaSCSI may have crashed."
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)
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abort(
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500, _(
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u"The RaSCSI Web Interface did not get a valid response from RaSCSI. "
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u"Please go back and try again. "
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u"If the issue persists, please report a bug."
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)
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)
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