PONSIM: PON simulator with real dataplane handling

This was needed because neither CPQD nor OVS can handle
both zero-tagged packets and 802.1ad (QinQ).

- extensive unittest proves ponsim functional correctness
  (for the common use-cases needed in the PON scenario)
- integrated with frameio and coupled with a rather
  simple gRPC NBI, ponsim can be operated from Voltha
  just like a real PON system
- posim_olt/_onu adapters added to Voltha to work on
  ponsim
- CLI can be used to preprovision and activate a PONSIM
  instance (e.g., preprovision_olt -t ponsim_olt -H localhost:50060)
- Some of olt-oftest:olt-complex testcases can be run on
  the ponsim device (in vagrant/Ubuntu environment),
  but there are some remaining issues to work out:
  - barrier calls in OF do not guaranty that the flow
    is already installed on the device. This is a generic
    issue, not just for ponsim.
  - the whole test framework is inconsistent about zero-
    tagged vs. untagged frames at the ONUs, while ponsim
    is rather pedantica and does exactly what was defined
    in the flows.

Change-Id: I0dd564c932416ae1566935492134cb5b08113bdc
diff --git a/ponsim/main.py b/ponsim/main.py
new file mode 100755
index 0000000..f3d0ffd
--- /dev/null
+++ b/ponsim/main.py
@@ -0,0 +1,214 @@
+#!/usr/bin/env python
+#
+# Copyright 2016 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# 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 License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+PON Simulator process, able to move packets across NNI and UNIs, as well
+as take MGMT calls via gRPC.
+It can only work on Linux.
+"""
+import argparse
+import os
+
+import yaml
+from twisted.internet.defer import inlineCallbacks
+
+from common.structlog_setup import setup_logging
+from grpc_server import GrpcServer
+from ponsim import PonSim
+from realio import RealIo
+
+defs = dict(
+    config=os.environ.get('CONFIG', './ponsim.yml'),
+    grpc_port=int(os.environ.get('GRPC_PORT', 50060)),
+    name=os.environ.get('NAME', 'pon1'),
+    onus=int(os.environ.get("ONUS", 1))
+)
+
+
+def load_config(args):
+    path = args.config
+    if path.startswith('.'):
+        dir = os.path.dirname(os.path.abspath(__file__))
+        path = os.path.join(dir, path)
+    path = os.path.abspath(path)
+    with open(path) as fd:
+        config = yaml.load(fd)
+    return config
+
+
+banner = r'''
+ ____   __   __ _  ____  __  _  _
+(  _ \ /  \ (  ( \/ ___)(  )( \/ )
+ ) __/(  O )/    /\___ \ )( / \/ \
+(__)   \__/ \_)__)(____/(__)\_)(_/
+'''
+
+def print_banner(log):
+    for line in banner.strip('\n').splitlines():
+        log.info(line)
+    log.info('(to stop: press Ctrl-C)')
+
+
+def parse_args():
+
+    parser = argparse.ArgumentParser()
+
+    _help = ('Path to chameleon.yml config file (default: %s). '
+             'If relative, it is relative to main.py of chameleon.'
+             % defs['config'])
+    parser.add_argument('-c', '--config',
+                        dest='config',
+                        action='store',
+                        default=defs['config'],
+                        help=_help)
+
+    _help = ('port number of the GRPC service exposed by voltha (default: %s)'
+             % defs['grpc_port'])
+    parser.add_argument('-g', '--grpc-port',
+                        dest='grpc_port',
+                        action='store',
+                        default=defs['grpc_port'],
+                        help=_help)
+
+    _help = ('number of ONUs to simulate (default: %d)' % defs['onus'])
+    parser.add_argument('-o', '--onus',
+                        dest='onus',
+                        action='store',
+                        type=int,
+                        default=defs['onus'],
+                        help=_help)
+
+    _help = ('name of the PON natework used as a prefix for all network'
+             ' resource created on behalf of the PON (default: %s)' %
+             defs['name'])
+    parser.add_argument('-N', '--name',
+                        dest='name',
+                        action='store',
+                        default=defs['name'],
+                        help=_help)
+
+    _help = "suppress debug and info logs"
+    parser.add_argument('-q', '--quiet',
+                        dest='quiet',
+                        action='count',
+                        help=_help)
+
+    _help = 'enable verbose logging'
+    parser.add_argument('-v', '--verbose',
+                        dest='verbose',
+                        action='count',
+                        help=_help)
+
+    _help = 'omit startup banner log lines'
+    parser.add_argument('-n', '--no-banner',
+                        dest='no_banner',
+                        action='store_true',
+                        default=False,
+                        help=_help)
+
+    args = parser.parse_args()
+
+    return args
+
+
+class Main(object):
+
+    def __init__(self):
+
+        self.args = args = parse_args()
+        self.config = load_config(args)
+
+        verbosity_adjust = (args.verbose or 0) - (args.quiet or 0)
+        self.log = setup_logging(self.config.get('logging', {}),
+                                 args.name,
+                                 verbosity_adjust=verbosity_adjust)
+
+        # components
+        self.io = None
+        self.ponsim = None
+        self.grpc_server = None
+
+        if not args.no_banner:
+            print_banner(self.log)
+
+        self.startup_components()
+
+    def start(self):
+        self.start_reactor()  # will not return except Keyboard interrupt
+
+    @inlineCallbacks
+    def startup_components(self):
+        try:
+            self.log.info('starting-internal-components')
+
+            iface_map = self.setup_networking_assets(self.args.name,
+                                                     self.args.onus)
+            self.io = yield RealIo(iface_map).start()
+            self.ponsim = PonSim(self.args.onus, self.io.egress)
+            self.io.register_ponsim(self.ponsim)
+
+            self.grpc_server = GrpcServer(self.args.grpc_port, self.ponsim)
+            yield self.grpc_server.start()
+
+            self.log.info('started-internal-services')
+
+        except Exception, e:
+            self.log.exception('startup-failed', e=e)
+
+    @inlineCallbacks
+    def shutdown_components(self):
+        """Execute before the reactor is shut down"""
+        self.log.info('exiting-on-keyboard-interrupt')
+        if self.io is not None:
+            self.io.stop()
+        self.teardown_networking_assets(self.args.name, self.args.onus)
+        if self.grpc_server is not None:
+            yield self.grpc_server.stop()
+
+    def start_reactor(self):
+        from twisted.internet import reactor
+        reactor.callWhenRunning(
+            lambda: self.log.info('twisted-reactor-started'))
+        reactor.addSystemEventTrigger('before', 'shutdown',
+                                      self.shutdown_components)
+        reactor.run()
+
+    def setup_networking_assets(self, prefix, n_unis):
+        # setup veth pairs for NNI and each UNI, using prefix and port numbers
+        port_map = dict()
+        for portnum in [0] + range(128, 128 + n_unis):
+            external_name = '%s_%d' % (prefix, portnum)
+            internal_name = external_name + 'sim'
+            os.system('sudo ip link add dev {} type veth peer name {}'.format(
+                external_name, internal_name
+            ))
+            os.system('sudo ip link set {} up'.format(external_name))
+            os.system('sudo ip link set {} up'.format(internal_name))
+            if portnum == 0:
+                os.system('sudo brctl addif ponmgmt {}'.format(external_name))
+            port_map[portnum] = internal_name
+        return port_map
+
+    def teardown_networking_assets(self, prefix, n_unis):
+        # undo all the networking stuff
+        for portnum in [0] + range(128, 128 + n_unis):
+            external_name = '%s_%d' % (prefix, portnum)
+            os.system('sudo ip link del {}'.format(external_name))
+
+
+if __name__ == '__main__':
+    Main().start()