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"""Multicast transport for stomp.py.
Obviously not a typical message broker, but convenient if you don't have a broker, but still want to use stomp.py
methods.
"""
import struct
from stomp.connect import BaseConnection
from stomp.protocol import *
from stomp.transport import *
from stomp.utils import *
MCAST_GRP = "224.1.1.1"
MCAST_PORT = 5000
class MulticastTransport(Transport):
"""
Transport over multicast connections rather than using a broker.
"""
def __init__(self, encoding):
Transport.__init__(self, [], False, False, 0.0, 0.0, 0.0, 0.0, 0, None, None, None, False, encoding)
self.subscriptions = {}
self.current_host_and_port = (MCAST_GRP, MCAST_PORT)
def attempt_connection(self):
"""
Establish a multicast connection - uses 2 sockets (one for sending, the other for receiving)
"""
self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
self.socket.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
self.receiver_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
self.receiver_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.receiver_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
self.receiver_socket.bind(("", MCAST_PORT))
mreq = struct.pack("4sl", socket.inet_aton(MCAST_GRP), socket.INADDR_ANY)
self.receiver_socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
if not self.socket or not self.receiver_socket:
raise exception.ConnectFailedException()
def send(self, encoded_frame):
"""
Send an encoded frame through the mcast socket.
:param bytes encoded_frame:
"""
self.socket.sendto(encoded_frame, (MCAST_GRP, MCAST_PORT))
def receive(self):
"""
Receive 1024 bytes from the multicast receiver socket.
:rtype: bytes
"""
return self.receiver_socket.recv(1024)
def process_frame(self, f, frame_str):
"""
:param Frame f: Frame object
:param bytes frame_str: Raw frame content
"""
frame_type = f.cmd.lower()
if frame_type in ["disconnect"]:
return
if frame_type == "send":
frame_type = "message"
f.cmd = "MESSAGE"
if frame_type in ["connected", "message", "receipt", "error", "heartbeat"]:
if frame_type == "message":
if f.headers["destination"] not in self.subscriptions.values():
return
self.notify("before_message", f)
self.notify(frame_type, f)
if "receipt" in f.headers:
receipt_frame = Frame("RECEIPT", {"receipt-id": f.headers["receipt"]})
lines = convert_frame(receipt_frame)
self.send(encode(pack(lines)))
logging.debug("received frame: %r, headers=%r, body=%r", f.cmd, f.headers, f.body)
def stop(self):
self.running = False
if hasattr(self.receiver_socket, "SHUT_RDWR"):
self.receiver_socket.shutdown(socket.SHUT_RDWR)
self.receiver_socket.close()
self.disconnect_socket()
Transport.stop(self)
class MulticastConnection(BaseConnection, Protocol12):
def __init__(self, encoding="utf-8"):
self.transport = MulticastTransport(encoding)
self.transport.set_listener("mcast-listener", self)
self.transactions = {}
Protocol12.__init__(self, self.transport, (0, 0))
def connect(self, username=None, passcode=None, wait=False, headers=None, **keyword_headers):
"""
:param str username:
:param str passcode:
:param bool wait:
:param dict headers:
:param keyword_headers:
"""
self.transport.start()
def subscribe(self, destination, id, ack="auto", headers=None, **keyword_headers):
"""
:param str destination:
:param str id:
:param str ack:
:param dict headers:
:param keyword_headers:
"""
self.transport.subscriptions[id] = destination
def unsubscribe(self, id, headers=None, **keyword_headers):
"""
:param str id:
:param dict headers:
:param keyword_headers:
"""
del self.transport.subscriptions[id]
def disconnect(self, receipt=None, headers=None, **keyword_headers):
"""
:param str receipt:
:param dict headers:
:param keyword_headers:
"""
Protocol12.disconnect(self, receipt, headers, **keyword_headers)
self.transport.stop()
def send_frame(self, cmd, headers=None, body=""):
"""
:param str cmd:
:param dict headers:
:param body:
"""
if headers is None:
headers = {}
frame = Frame(cmd, headers, body)
if cmd == CMD_BEGIN:
trans = headers[HDR_TRANSACTION]
if trans in self.transactions:
self.notify("error", Frame(None, {}, "Transaction %s already started" % trans))
else:
self.transactions[trans] = []
elif cmd == CMD_COMMIT:
trans = headers[HDR_TRANSACTION]
if trans not in self.transactions:
self.notify("error", Frame(None, {}, "Transaction %s not started" % trans))
else:
for f in self.transactions[trans]:
self.transport.transmit(f)
del self.transactions[trans]
elif cmd == CMD_ABORT:
trans = headers["transaction"]
del self.transactions[trans]
else:
if "transaction" in headers:
trans = headers["transaction"]
if trans not in self.transactions:
self.transport.notify("error", Frame(None, {}, "Transaction %s not started" % trans))
return
else:
self.transactions[trans].append(frame)
else:
self.transport.transmit(frame)
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