pyloxi: Connection class
This class creates a thread which continually parses OpenFlow messages off the
supplied socket and places them in a queue. The class has methods for reading messages
from the RX queue, sending messages, and higher level operations like request-response
and multipart transactions.
I'm putting this in Loxigen because it's so commonly used even though it goes
beyond the usual LOXI scope of serialization.
diff --git a/py_gen/codegen.py b/py_gen/codegen.py
index 9c741d2..aa7141a 100644
--- a/py_gen/codegen.py
+++ b/py_gen/codegen.py
@@ -88,6 +88,7 @@
render('__init__.py', template_name='toplevel_init.py')
render('pp.py')
render('generic_util.py')
+ render('connection.py')
for version in loxi_globals.OFVersions.all_supported:
subdir = 'of' + version.version.replace('.', '')
diff --git a/py_gen/templates/connection.py b/py_gen/templates/connection.py
new file mode 100644
index 0000000..ac3fbc1
--- /dev/null
+++ b/py_gen/templates/connection.py
@@ -0,0 +1,260 @@
+:: # Copyright 2015, Big Switch Networks, Inc.
+:: #
+:: # LoxiGen is licensed under the Eclipse Public License, version 1.0 (EPL), with
+:: # the following special exception:
+:: #
+:: # LOXI Exception
+:: #
+:: # As a special exception to the terms of the EPL, you may distribute libraries
+:: # generated by LoxiGen (LoxiGen Libraries) under the terms of your choice, provided
+:: # that copyright and licensing notices generated by LoxiGen are not altered or removed
+:: # from the LoxiGen Libraries and the notice provided below is (i) included in
+:: # the LoxiGen Libraries, if distributed in source code form and (ii) included in any
+:: # documentation for the LoxiGen Libraries, if distributed in binary form.
+:: #
+:: # Notice: "Copyright 2013, Big Switch Networks, Inc. This library was generated by the LoxiGen Compiler."
+:: #
+:: # You may not use this file except in compliance with the EPL or LOXI Exception. You may obtain
+:: # a copy of the EPL at:
+:: #
+:: # http://www.eclipse.org/legal/epl-v10.html
+:: #
+:: # Unless required by applicable law or agreed to in writing, software
+:: # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+:: # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+:: # EPL for the specific language governing permissions and limitations
+:: # under the EPL.
+::
+# Copyright 2015, Big Switch Networks, Inc.
+
+"""
+OpenFlow connection class
+
+This class creates a thread which continually parses OpenFlow messages off the
+supplied socket and places them in a queue. The class has methods for reading messages
+from the RX queue, sending messages, and higher level operations like request-response
+and multipart transactions.
+"""
+
+import loxi
+import loxi.of14
+import logging
+import time
+import socket
+import errno
+import os
+import select
+from threading import Condition, Lock, Thread
+
+DEFAULT_TIMEOUT = 1
+
+class TransactionError(Exception):
+ def __str__(self):
+ return self.args[0]
+
+ @property
+ def msg(self):
+ return self.args[1]
+
+class Connection(Thread):
+ def __init__(self, sock):
+ Thread.__init__(self)
+ self.sock = sock
+ self.logger = logging.getLogger("connection")
+ self.rx = []
+ self.rx_cv = Condition()
+ self.tx_lock = Lock()
+ self.next_xid = 1
+ self.wakeup_rd, self.wakeup_wr = os.pipe()
+ self.finished = False
+ self.read_buffer = None
+
+ def run(self):
+ while not self.finished:
+ rd, wr, err = select.select([self.sock, self.wakeup_rd], [], [])
+ if self.sock in rd:
+ self.process_read()
+ if self.wakeup_rd in rd:
+ os.read(self.wakeup_rd, 1)
+ self.logger.debug("Exited event loop")
+
+ def process_read(self):
+ recvd = self.sock.recv(4096)
+
+ self.logger.debug("Received %d bytes", len(recvd))
+
+ buf = self.read_buffer
+ if buf:
+ buf += recvd
+ else:
+ buf = recvd
+
+ offset = 0
+ while offset < len(buf):
+ if offset + 8 > len(buf):
+ # Not enough data for the OpenFlow header
+ break
+
+ # Parse the header to get type
+ hdr_version, hdr_type, hdr_length, hdr_xid = loxi.of14.message.parse_header(buf[offset:])
+
+ # Use loxi to resolve to ofp of matching version
+ ofp = loxi.protocol(hdr_version)
+
+ # Extract the raw message bytes
+ if (offset + hdr_length) > len(buf):
+ # Not enough data for the body
+ break
+ rawmsg = buf[offset : offset + hdr_length]
+ offset += hdr_length
+
+ msg = ofp.message.parse_message(rawmsg)
+ if not msg:
+ self.logger.warn("Could not parse message")
+ continue
+
+ self.logger.debug("Received message %s.%s xid %d length %d",
+ type(msg).__module__, type(msg).__name__, hdr_xid, hdr_length)
+
+ with self.rx_cv:
+ self.rx.append(msg)
+ self.rx_cv.notify_all()
+
+ if offset == len(buf):
+ self.read_buffer = None
+ else:
+ self.read_buffer = buf[offset:]
+ self.logger.debug("%d bytes remaining", len(self.read_buffer))
+
+ def recv(self, predicate, timeout=DEFAULT_TIMEOUT):
+ """
+ Remove and return the first message in the RX queue for
+ which 'predicate' returns true
+ """
+ assert self.is_alive()
+
+ deadline = time.time() + timeout
+ while True:
+ with self.rx_cv:
+ for i, msg in enumerate(self.rx):
+ if predicate(msg):
+ return self.rx.pop(i)
+
+ now = time.time()
+ if now > deadline:
+ return None
+ else:
+ self.rx_cv.wait(deadline - now)
+
+ def recv_any(self, timeout=DEFAULT_TIMEOUT):
+ """
+ Return the first message in the RX queue
+ """
+ return self.recv(lambda msg: True, timeout)
+
+ def recv_xid(self, xid, timeout=DEFAULT_TIMEOUT):
+ """
+ Return the first message in the RX queue with XID 'xid'
+ """
+ return self.recv(lambda msg: msg.xid == xid, timeout)
+
+ def recv_class(self, klass, timeout=DEFAULT_TIMEOUT):
+ """
+ Return the first message in the RX queue which is an instance of 'klass'
+ """
+ return self.recv(lambda msg: isinstance(msg, klass), timeout)
+
+ def send_raw(self, buf):
+ """
+ Send raw bytes on the socket
+ """
+ assert self.is_alive()
+ self.logger.debug("Sending raw message length %d", len(buf))
+ with self.tx_lock:
+ if self.sock.sendall(buf) is not None:
+ raise RuntimeError("failed to send message to switch")
+
+ def send(self, msg):
+ """
+ Send a message
+ """
+ assert self.is_alive()
+
+ if msg.xid is None:
+ msg.xid = self._gen_xid()
+ buf = msg.pack()
+ self.logger.debug("Sending message %s.%s xid %d length %d",
+ type(msg).__module__, type(msg).__name__, msg.xid, len(buf))
+ with self.tx_lock:
+ if self.sock.sendall(buf) is not None:
+ raise RuntimeError("failed to send message to switch")
+
+ def transact(self, msg, timeout=DEFAULT_TIMEOUT):
+ """
+ Send a message and return the reply
+ """
+ self.send(msg)
+ reply = self.recv_xid(msg.xid, timeout)
+ if reply is None:
+ raise TransactionError("no reply for %s" % type(msg).__name__, None)
+ elif isinstance(reply, loxi.protocol(reply.version).message.error_msg):
+ raise TransactionError("received %s in response to %s" % (type(reply).__name__, type(msg).__name__), reply)
+ return reply
+
+ def transact_multipart_generator(self, msg, timeout=DEFAULT_TIMEOUT):
+ """
+ Send a multipart request and yield each entry from the replies
+ """
+ self.send(msg)
+ finished = False
+ while not finished:
+ reply = self.recv_xid(msg.xid, timeout)
+ if reply is None:
+ raise TransactionError("no reply for %s" % type(msg).__name__, None)
+ elif not isinstance(reply, loxi.protocol(reply.version).message.stats_reply):
+ raise TransactionError("received %s in response to %s" % (type(reply).__name__, type(msg).__name__), reply)
+ for entry in reply.entries:
+ yield entry
+ finished = reply.flags & loxi.protocol(reply.version).OFPSF_REPLY_MORE == 0
+
+ def transact_multipart(self, msg, timeout=DEFAULT_TIMEOUT):
+ """
+ Send a multipart request and return all entries from the replies
+ """
+ entries = []
+ for entry in self.transact_multipart_generator(msg, timeout):
+ entries.append(entry)
+ return entries
+
+ def stop(self):
+ """
+ Signal the thread to exit and wait for it
+ """
+ assert not self.finished
+ self.logger.debug("Stopping connection")
+ self.finished = True
+ os.write(self.wakeup_wr, "x")
+ self.join()
+ self.sock.close()
+ os.close(self.wakeup_rd)
+ os.close(self.wakeup_wr)
+ self.logger.debug("Stopped connection")
+
+ def _gen_xid(self):
+ xid = self.next_xid
+ self.next_xid += 1
+ return xid
+
+def connect(ip, port=6653, daemon=True, ofp=loxi.of14):
+ """
+ Actively connect to a switch
+ """
+ soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+ soc.connect((ip, port))
+ soc.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True)
+ cxn = Connection(soc)
+ cxn.daemon = daemon
+ cxn.logger.debug("Connected to %s:%d", ip, port)
+ cxn.start()
+ cxn.send(ofp.message.hello())
+ return cxn