#!/usr/bin/env python
#
# xapi plugin script to update the cache of configuration items in the
# ovs-vswitchd configuration that are managed in the xapi database when 
# integrated with Citrix management tools.

# Copyright (C) 2009, 2010 Nicira Networks, Inc.
#
# 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.

# TBD: - error handling needs to be improved.  Currently this can leave
# TBD:   the system in a bad state if anything goes wrong.

import XenAPIPlugin
import XenAPI
import os
import subprocess
import syslog

vsctl="/usr/bin/ovs-vsctl"
cacert_filename="/etc/openvswitch/vswitchd.cacert"

# Delete the CA certificate, so that we go back to boot-strapping mode
def delete_cacert():
    try:
        os.remove(cacert_filename)
    except OSError:
        # Ignore error if file doesn't exist
        pass

def update(session, args):
    # Refresh bridge network UUIDs in case this host joined or left a pool.
    script = "/opt/xensource/libexec/interface-reconfigure"
    try:
        retval = subprocess.call([script, "rewrite"])
        if retval != 0:
            syslog.syslog("%s exited with status %d" % (script, retval))
    except OSError, e:
        syslog.syslog("%s: failed to execute (%s)" % (script, e.strerror))

    pools = session.xenapi.pool.get_all()
    # We assume there is only ever one pool...
    if len(pools) == 0:
        raise XenAPIPlugin.Failure("NO_POOL_FOR_HOST", [])
    if len(pools) > 1:
        raise XenAPIPlugin.Failure("MORE_THAN_ONE_POOL_FOR_HOST", [])
    pool = session.xenapi.pool.get_record(pools[0])
    try:
        try:
            controller = pool["vswitch_controller"]
        except KeyError:
            # On systems older than XenServer 5.6.0, we needed to store
            # the key in "other_config".
            controller = pool["other_config"]["vSwitchController"]
    except KeyError, e:
        controller = ""
    currentController = vswitchCurrentController()
    if controller == "" and currentController != "":
        delete_cacert()
        try:
            emergency_reset(session, None)
        except:
            pass
        removeControllerCfg()
        return "Successfully removed controller config"
    elif controller != currentController:
        delete_cacert()
        try:
            emergency_reset(session, None)
        except:
            pass
        setControllerCfg(controller)
        return "Successfully set controller to " + controller
    else:
        return "No change to configuration"

def vswitchCurrentController():
    controller = vswitchCfgQuery(["get", "Open_vSwitch", 
                                  ".", "managers"]).strip('[]"')
    if controller == "":
        return controller
    if len(controller) < 4 or controller[0:4] != "ssl:":
        return controller
    else:
        return controller.split(':')[1]

def removeControllerCfg():
    vswitchCfgMod(["--", "clear", "Open_vSwitch", ".", "managers",
                   "--", "del-ssl"])

def setControllerCfg(controller):
    # /etc/xensource/xapi-ssl.pem is mentioned twice below because it
    # contains both the private key and the certificate.
    vswitchCfgMod(["--", "clear", "Open_vSwitch", ".", "managers",
                   "--", "del-ssl",
                   "--", "--bootstrap", "set-ssl",
                   "/etc/xensource/xapi-ssl.pem",
                   "/etc/xensource/xapi-ssl.pem",
                   cacert_filename,
                   "--", "set", "Open_vSwitch", ".",
                   'managers="ssl:' + controller + ':6632"'])

def vswitchCfgQuery(action_args):
    cmd = [vsctl, "--timeout=5", "-vANY:console:emer"] + action_args
    output = subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()
    if len(output) == 0 or output[0] == None:
        output = ""
    else:
        output = output[0].strip()
    return output

def vswitchCfgMod(action_args):
    cmd = [vsctl, "--timeout=5", "-vANY:console:emer"] + action_args
    exitcode = subprocess.call(cmd)
    if exitcode != 0:
        raise XenAPIPlugin.Failure("VSWITCH_CONFIG_MOD_FAILURE",
                                   [ str(exitcode) , str(action_args) ])

def emergency_reset(session, args):
    cmd = [vsctl, "--timeout=5", "emer-reset"]
    exitcode = subprocess.call(cmd)
    if exitcode != 0:
        raise XenAPIPlugin.Failure("VSWITCH_EMER_RESET_FAILURE",
                                   [ str(exitcode) ])

    return "Successfully reset configuration"
    
if __name__ == "__main__":
    XenAPIPlugin.dispatch({"update": update,
                           "emergency_reset": emergency_reset})