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

# Copyright (C) 2009 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

vsctl="/usr/bin/ovs-vsctl"
cacert_filename="/etc/ovs-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):
    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:
        controller = pool["other_config"]["vSwitchController"]
    except KeyError, e:
        controller = ""
    if controller == "do-not-update":
        return "XAPI key set to do-not-update"
    if controller.startswith("for-bridges|"):
        l = controller.split("|")[1:]
        for netctrl in l:
            xapiNet = session.xenapi.network
            n, t = netctrl.split("=")
            blist = xapiNet.get_by_name_label(n)
            if len(blist) == 0:
                # If there is no bridge for the network, just keep
                # going so we bring up as much as possible.
                continue
            elif len(blist) > 1:
                raise XenAPIPlugin.Failure("TOO_MANY_MATCHING_NETWORKS", [n,blist])
            b = xapiNet.get_bridge(blist[0])
            setBrControllerCfg(b, t)
        return "Completed setting controllers on specific bridges"
    currentController = vswitchCurrentController()
    if controller == "" and currentController != "":
        delete_cacert()
        removeControllerCfg()
        return "Successfully removed controller config"
    elif controller != currentController:
        delete_cacert()
        setControllerCfg(controller)
        return "Successfully set controller to " + controller
    else:
        return "No change to configuration"

def vswitchCurrentController():
    controller = vswitchCfgQuery("get-controller")
    if controller == "":
        return controller
    if len(controller) < 4 or controller[0:4] != "ssl:":
        return controller
    else:
        return controller[4:]

def removeControllerCfg():
    vswitchCfgMod(["--", "del-controller",
                   "--", "del-ssl"])

def setBrControllerCfg(br, target):
    # Terrible hack... When this is run at boot the required bridges
    # may not be present.  So, we fork a process for each bridge that
    # needs to be set which sits around in the background and updates
    # it when it becomes available, finally timing out after a long
    # interval if it never becomes available.
    #
    # The right way to do this is to hook the bridge creation somehow
    # but I don't believe this is possible in XenServer 5.5 without
    # either listening to XAPI events or writing it in C code in
    # brcompatd.
    import time
    import syslog
    import resource

    p = os.fork()
    if p != 0:
        return

    os.setsid()
    p = os.fork()
    if p != 0:
        sys.exit(0)

    os.chdir("/")
    os.umask(0)
    maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
    if maxfd == resource.RLIM_INFINITY:
        maxfd = 1024
    for fd in range(0, maxfd):
        try:
            os.close(fd)
        except OSError:
            pass
    os.open("/dev/null", os.O_RDWR)
    os.dup2(0, 1)
    os.dup2(0, 2)

    syslog.openlog("vswitch-cfg-update", syslog.LOG_PID)
    syslog.syslog(syslog.LOG_INFO,
                  "Started background process waiting on bridge %s" % (br,))

    count = 0
    error = None
    sleep_time = 10
    while count < 60:
        count += 1
        try:
            vswitchCfgMod(["--", "del-controller", br,
                           "--", "set-controller", br, target,
                           "--", "set-fail-mode", br, "secure"])
        except XenAPIPlugin.Failure, e:
            error = e
            syslog.syslog(syslog.LOG_INFO,
                          "Attempt to set br %s controller failed" % (br,))
            time.sleep(sleep_time)
            continue
        syslog.syslog(syslog.LOG_INFO,
                      "Successfully set br %s controller to %s" % (br, repr(target)))
        return
    syslog.syslog(syslog.LOG_ERR,
                  "Giving up on setting br %s controller" % (br,))

def setControllerCfg(controller):
    vswitchCfgMod(["--", "del-controller",
                   "--", "del-ssl",
                   "--", "--bootstrap", "set-ssl",
                   "/etc/xensource/xapi-ssl.pem",
                   "/etc/xensource/xapi-ssl.pem",
                   "/etc/ovs-vswitchd.cacert",
                   "--", "set-controller", "ssl:" + controller])

def vswitchCfgQuery(action):
    cmd = [vsctl, "-vANY:console:emer", action]
    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, "-vANY:console:emer"] + action_args
    exitcode = subprocess.call(cmd)
    if exitcode != 0:
        raise XenAPIPlugin.Failure("VSWITCH_CONFIG_MOD_FAILURE",
                                   [ str(exitcode) , str(action_args) ])
    
if __name__ == "__main__":
    XenAPIPlugin.dispatch({"update": update})