mirror of
https://github.com/akuker/RASCSI.git
synced 2024-06-06 07:29:30 +00:00
52c2aa474f
* Rebrand project to PiSCSI - rascsi ->piscsi - rasctl -> scsictl - rasdump -> scsidump - ras* -> piscsi* (rasutil -> piscsi_util, etc.) * Refined the formatting and wording of the app startup banner * Kept some references to rascsi and rasctl where backwards compatibility is concerned * Point to the new github repo URL Co-authored-by: nucleogenic <nr@nucleogenic.com> Co-authored-by: Uwe Seimet <Uwe.Seimet@seimet.de>
103 lines
3.5 KiB
Python
103 lines
3.5 KiB
Python
"""
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Module for sending and receiving data over a socket connection with the PiSCSI backend
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"""
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import logging
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import socket
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from time import sleep
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from struct import pack, unpack
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from piscsi.exceptions import (
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EmptySocketChunkException,
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InvalidProtobufResponse,
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FailedSocketConnectionException,
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)
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class SocketCmds:
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"""
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Class for sending and receiving data over a socket connection with the PiSCSI backend
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"""
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def __init__(self, host="localhost", port=6868):
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self.host = host
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self.port = port
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def send_pb_command(self, 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 PiSCSI.
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"""
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counter = 0
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tries = 20
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error_msg = ""
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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((self.host, self.port))
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response = self.send_over_socket(sock, payload)
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return response
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except socket.error as error:
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counter += 1
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logging.warning(
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"The PiSCSI service is not responding - attempt %s/%s",
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str(counter),
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str(tries),
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)
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error_msg = str(error)
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sleep(0.2)
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except EmptySocketChunkException as ex:
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raise ex
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except InvalidProtobufResponse as ex:
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raise ex
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logging.error(error_msg)
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raise FailedSocketConnectionException(error_msg)
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# pylint: disable=no-self-use
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def send_over_socket(self, 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 PiSCSI 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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# 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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error_message = (
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"Read an empty chunk from the socket. Socket connection has "
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"dropped unexpectedly. PiSCSI may have crashed."
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)
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logging.error(error_message)
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raise EmptySocketChunkException(error_message)
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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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error_message = (
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"The response from PiSCSI did not contain a protobuf header. "
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"PiSCSI may have crashed."
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)
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logging.error(error_message)
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raise InvalidProtobufResponse(error_message)
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