#!/usr/bin/python
# Copyright (c) 2009, 2010 Nicira Networks
#
# 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.


# A daemon to monitor the external_ids columns of the Bridge and
# Interface OVSDB tables.  Its primary responsibility is to set the
# "bridge-id" and "iface-id" keys in the Bridge and Interface tables,
# respectively.  It also looks for the use of "network-uuids" in the
# Bridge table and duplicates its value to the preferred "xs-network-uuids".

import getopt
import logging, logging.handlers
import os
import signal
import subprocess
import sys
import time

import XenAPI

from ovs.db import error
from ovs.db import types
import ovs.util
import ovs.daemon
import ovs.db.idl

s_log     = logging.getLogger("ovs-external-ids")
l_handler = logging.handlers.RotatingFileHandler(
        "/var/log/openvswitch/ovs-external-ids.log")
l_formatter = logging.Formatter('%(filename)s: %(levelname)s: %(message)s')
l_handler.setFormatter(l_formatter)
s_log.addHandler(l_handler)
s_log.setLevel(logging.INFO)

vsctl="/usr/bin/ovs-vsctl"
session = None
force_run = False

# Set up a session to interact with XAPI.
#
# On system start-up, OVS comes up before XAPI, so we can't log into the
# session until later.  Try to do this on-demand, since we won't
# actually do anything interesting until XAPI is up.
def init_session():
    global session
    if session is not None:
        return True

    try:
        session = XenAPI.xapi_local()
        session.xenapi.login_with_password("", "")
    except:
        session = None
        s_log.warning("Couldn't login to XAPI")
        return False

    return True

# By default, the "bridge-id" external id in the Bridge table is the
# same as "xs-network-uuids".  This may be overridden by defining a
# "nicira-bridge-id" key in the "other_config" field of the network
# record of XAPI.
def get_bridge_id(br_name, default=None):
    if not init_session():
        s_log.warning("Failed to get bridge id %s because"
                " XAPI session could not be initialized" % br_name)
        return default

    for n in session.xenapi.network.get_all():
        rec = session.xenapi.network.get_record(n)
        if rec['bridge'] != br_name:
            continue
        return rec['other_config'].get('nicira-bridge-id', default)

# By default, the "iface-id" external id in the Interface table is the
# same as "xs-vif-uuid".  This may be overridden by defining a
# "nicira-iface-id" key in the "other_config" field of the VIF
# record of XAPI.
def get_iface_id(if_name, xs_vif_uuid):
    if not if_name.startswith("vif"):
        # Treat whatever was passed into 'xs_vif_uuid' as a default
        # value for non-VIFs.
        return xs_vif_uuid

    if not init_session():
        s_log.warning("Failed to get interface id %s because"
                " XAPI session could not be initialized" % if_name)
        return xs_vif_uuid

    try:
        vif = session.xenapi.VIF.get_by_uuid(xs_vif_uuid)
        rec = session.xenapi.VIF.get_record(vif)
        return rec['other_config'].get('nicira-iface-id', xs_vif_uuid)
    except XenAPI.Failure:
        s_log.warning("Could not find XAPI entry for VIF %s" % if_name)
        return xs_vif_uuid

def set_external_id(table, record, key, value):
    col = 'external-ids:"' + key + '"="' + value + '"'
    cmd = [vsctl, "--timeout=30", "-vANY:console:emer", "set", table, record, col]
    exitcode = subprocess.call(cmd)
    if exitcode != 0:
        s_log.warning("Couldn't call ovs-vsctl")

# XAPI on XenServer 5.6 uses the external-id "network-uuids" for internal
# networks, but we now prefer "xs-network-uuids".  Look for its use and
# write our preferred external-id.
def update_network_uuids(name, ids):
    if ids["network-uuids"] and not ids["xs-network-uuids"]:
        set_external_id("Bridge", name, "xs-network-uuids",
                ids["network-uuids"])

def update_bridge_id(name, ids):
    id = get_bridge_id(name, ids.get("xs-network-uuids"))

    if not id:
        return

    primary_id = id.split(";")[0]

    if ids.get("bridge-id") != primary_id:
        set_external_id("Bridge", name, "bridge-id", primary_id)

def update_iface_id(name, ids):
    id = get_iface_id(name, ids.get("xs-vif-uuid"))
    if ids.get("iface-id") != id and id:
        set_external_id("Interface", name, "iface-id", id)

def keep_table_columns(schema, table_name, column_types):
    table = schema.tables.get(table_name)
    if not table:
        raise error.Error("schema has no %s table" % table_name)

    new_columns = {}
    for column_name, column_type in column_types.iteritems():
        column = table.columns.get(column_name)
        if not column:
            raise error.Error("%s table schema lacks %s column"
                              % (table_name, column_name))
        if column.type != column_type:
            raise error.Error("%s column in %s table has type \"%s\", "
                              "expected type \"%s\""
                              % (column_name, table_name,
                                 column.type.toEnglish(),
                                 column_type.toEnglish()))
        new_columns[column_name] = column
    table.columns = new_columns
    return table

def monitor_uuid_schema_cb(schema):
    string_type = types.Type(types.BaseType(types.StringType))
    string_map_type = types.Type(types.BaseType(types.StringType),
                                 types.BaseType(types.StringType),
                                 0, sys.maxint)

    new_tables = {}
    for table_name in ("Bridge", "Interface"):
        new_tables[table_name] = keep_table_columns(
            schema, table_name, {"name": string_type,
                                 "external_ids": string_map_type})
    schema.tables = new_tables

def usage():
    print "usage: %s [OPTIONS] DATABASE" % sys.argv[0]
    print "where DATABASE is a socket on which ovsdb-server is listening."
    ovs.daemon.usage()
    print "Other options:"
    print "  -h, --help               display this help message"
    sys.exit(0)

def handler(signum, frame):
    global force_run
    if (signum == signal.SIGHUP):
        force_run = True

def main(argv):
    global force_run

    try:
        options, args = getopt.gnu_getopt(
            argv[1:], 'h', ['help'] + ovs.daemon.LONG_OPTIONS)
    except getopt.GetoptError, geo:
        sys.stderr.write("%s: %s\n" % (ovs.util.PROGRAM_NAME, geo.msg))
        sys.exit(1)

    for key, value in options:
        if key in ['-h', '--help']:
            usage()
        elif not ovs.daemon.parse_opt(key, value):
            sys.stderr.write("%s: unhandled option %s\n"
                             % (ovs.util.PROGRAM_NAME, key))
            sys.exit(1)

    if len(args) != 1:
        sys.stderr.write("%s: exactly one nonoption argument is required "
                         "(use --help for help)\n" % ovs.util.PROGRAM_NAME)
        sys.exit(1)

    ovs.daemon.die_if_already_running()

    remote = args[0]
    idl = ovs.db.idl.Idl(remote, "Open_vSwitch", monitor_uuid_schema_cb)

    ovs.daemon.daemonize()

    # This daemon is usually started before XAPI, but to complete our
    # tasks, we need it.  Wait here until it's up.
    while not os.path.exists("/var/run/xapi_init_complete.cookie"):
        time.sleep(1)

    signal.signal(signal.SIGHUP, handler)

    bridges = {}
    interfaces = {}
    while True:
        if not force_run and not idl.run():
            poller = ovs.poller.Poller()
            idl.wait(poller)
            poller.block()
            continue

        if force_run:
            s_log.info("Forced to re-run as the result of a SIGHUP")
            bridges    = {}
            interfaces = {}
            force_run  = False

        new_bridges = {}
        for rec in idl.data["Bridge"].itervalues():
            name = rec.name.as_scalar()
            xs_network_uuids = rec.external_ids.get("xs-network-uuids")
            network_uuids = rec.external_ids.get("network-uuids")
            new_bridges[name] = {"xs-network-uuids": xs_network_uuids,
                                 "network-uuids": network_uuids}

        new_interfaces = {}
        for rec in idl.data["Interface"].itervalues():
            name = rec.name.as_scalar()
            xs_vif_uuid = rec.external_ids.get("xs-vif-uuid")
            new_interfaces[name] = {"xs-vif-uuid": xs_vif_uuid}

        if bridges != new_bridges:
            for name,ids in new_bridges.items():
                # Network uuids shouldn't change in the life of a bridge,
                # so only check for "network-uuids" on creation.
                if name not in bridges:
                    update_network_uuids(name, ids)

                if (name not in bridges) or (bridges[name] != ids):
                    update_bridge_id(name, ids)

            bridges = new_bridges

        if interfaces != new_interfaces:
            for name,ids in new_interfaces.items():
                if (name not in interfaces) or (interfaces[name] != ids):
                    update_iface_id(name, ids)
            interfaces = new_interfaces

if __name__ == '__main__':
    try:
        main(sys.argv)
    except SystemExit:
        # Let system.exit() calls complete normally
        raise
    except:
        s_log.exception("traceback")
        sys.exit(ovs.daemon.RESTART_EXIT_CODE)