#!@PYTHON@

# Copyright (C) 2010  Internet Systems Consortium.
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

''' cmdctl module is the configuration entry point for all commands from bindctl
or some other web tools client of bind10. cmdctl is pure https server which provi-
des RESTful API. When command client connecting with cmdctl, it should first login
with legal username and password.
    When cmdctl starting up, it will collect command specification and
configuration specification/data of other available modules from configmanager, then
wait for receiving request from client, parse the request and resend the request to
the proper module. When getting the request result from the module, send back the
resut to client.
'''

import sys; sys.path.append ('@@PYTHONPATH@@')
import os
import socketserver
import http.server
import urllib.parse
import json
import re
import ssl, socket
import isc
import pprint
import select
import csv
import random
import time
import signal
from isc.config import ccsession
import isc.util.process
import isc.net.parse
from optparse import OptionParser, OptionValueError
from hashlib import sha1
from isc.util import socketserver_mixin
from isc.log_messages.cmdctl_messages import *

isc.log.init("b10-cmdctl", buffer=True)
logger = isc.log.Logger("cmdctl")

# Debug level for communication with BIND10
DBG_CMDCTL_MESSAGING = logger.DBGLVL_COMMAND

try:
    import threading
except ImportError:
    import dummy_threading as threading

isc.util.process.rename()

__version__ = 'BIND10'
URL_PATTERN = re.compile('/([\w]+)(?:/([\w]+))?/?')
CONFIG_DATA_URL = 'config_data'
MODULE_SPEC_URL = 'module_spec'


# If B10_FROM_BUILD is set in the environment, we use data files
# from a directory relative to that, otherwise we use the ones
# installed on the system
if "B10_FROM_BUILD" in os.environ:
    SPECFILE_PATH = os.environ["B10_FROM_BUILD"] + "/src/bin/cmdctl"
else:
    PREFIX = "@prefix@"
    DATAROOTDIR = "@datarootdir@"
    SPECFILE_PATH = "@datadir@/@PACKAGE@".replace("${datarootdir}", DATAROOTDIR).replace("${prefix}", PREFIX)
SPECFILE_LOCATION = SPECFILE_PATH + os.sep + "cmdctl.spec"

class CmdctlException(Exception):
    pass

class SecureHTTPRequestHandler(http.server.BaseHTTPRequestHandler):
    '''https connection request handler.
    Currently only GET and POST are supported.  '''
    def do_GET(self):
        '''The client should send its session id in header with
        the name 'cookie'
        '''
        self.session_id = self.headers.get('cookie')
        rcode, reply = http.client.OK, []
        if self._is_session_valid():
            if self._is_user_logged_in():
                rcode, reply = self._handle_get_request()
            else:
                rcode, reply = http.client.UNAUTHORIZED, ["please login"]
        else:
            rcode = http.client.BAD_REQUEST

        self.send_response(rcode)
        self.end_headers()
        self.wfile.write(json.dumps(reply).encode())

    def _handle_get_request(self):
        '''Currently only support the following three url GET request '''
        id, module = self._parse_request_path()
        return self.server.get_reply_data_for_GET(id, module)

    def _is_session_valid(self):
        return self.session_id

    def _is_user_logged_in(self):
        login_time = self.server.user_sessions.get(self.session_id)
        if not login_time:
            return False

        idle_time = time.time() - login_time
        if idle_time > self.server.idle_timeout:
            return False
        # Update idle time
        self.server.user_sessions[self.session_id] = time.time()
        return True

    def _parse_request_path(self):
        '''Parse the url, the legal url should like /ldh or /ldh/ldh '''
        groups = URL_PATTERN.match(self.path)
        if not groups:
            return (None, None)
        else:
            return (groups.group(1), groups.group(2))

    def do_POST(self):
        '''Process POST request. '''
        '''Process user login and send command to proper module
        The client should send its session id in header with
        the name 'cookie'
        '''
        self.session_id = self.headers.get('cookie')
        rcode, reply = http.client.OK, []
        if self._is_session_valid():
            if self.path == '/login':
                rcode, reply = self._handle_login()
            elif self._is_user_logged_in():
                rcode, reply = self._handle_post_request()
            else:
                rcode, reply = http.client.UNAUTHORIZED, ["please login"]
        else:
            rcode, reply = http.client.BAD_REQUEST, ["session isn't valid"]

        self.send_response(rcode)
        self.end_headers()
        self.wfile.write(json.dumps(reply).encode())


    def _handle_login(self):
        if self._is_user_logged_in():
            return http.client.OK, ["user has already login"]
        is_user_valid, error_info = self._check_user_name_and_pwd()
        if is_user_valid:
            self.server.save_user_session_id(self.session_id)
            return http.client.OK, ["login success "]
        else:
            return http.client.UNAUTHORIZED, error_info

    def _check_user_name_and_pwd(self):
        '''Check user name and its password '''
        length = self.headers.get('Content-Length')

        if not length:
            return False, ["invalid username or password"]

        try:
            user_info = json.loads((self.rfile.read(int(length))).decode())
        except:
            return False, ["invalid username or password"]

        user_name = user_info.get('username')
        if not user_name:
            return False, ["need user name"]
        if not self.server.get_user_info(user_name):
            logger.info(CMDCTL_NO_SUCH_USER, user_name)
            return False, ["username or password error"]

        user_pwd = user_info.get('password')
        if not user_pwd:
            return False, ["need password"]
        local_info = self.server.get_user_info(user_name)
        pwd_hashval = sha1((user_pwd + local_info[1]).encode())
        if pwd_hashval.hexdigest() != local_info[0]:
            logger.info(CMDCTL_BAD_PASSWORD, user_name)
            return False, ["username or password error"]

        return True, None


    def _handle_post_request(self):
        '''Handle all the post request from client. '''
        mod, cmd = self._parse_request_path()
        if (not mod) or (not cmd):
            return http.client.BAD_REQUEST, ['malformed url']

        param = None
        len = self.headers.get('Content-Length')
        if len:
            try:
                post_str = str(self.rfile.read(int(len)).decode())
                param = json.loads(post_str)
            except:
                pass

        rcode, reply = self.server.send_command_to_module(mod, cmd, param)
        ret = http.client.OK
        if rcode != 0:
            ret = http.client.BAD_REQUEST
        return ret, reply

    def log_request(self, code='-', size='-'):
        '''Rewrite the log request function, log nothing.'''
        pass


class CommandControl():
    '''Get all modules' config data/specification from configmanager.
    receive command from client and resend it to proper module.
    '''
    def __init__(self, httpserver, verbose = False):
        ''' httpserver: the http server which use the object of
        CommandControl to communicate with other modules. '''
        self._verbose = verbose
        self._httpserver = httpserver
        self._lock = threading.Lock()
        self._setup_session()
        self.modules_spec = self._get_modules_specification()
        self._config_data = self._get_config_data_from_config_manager()
        self._serving = True
        self._start_msg_handle_thread()

    def _setup_session(self):
        '''Setup the session for receving the commands
        sent from other modules. There are two sessions
        for cmdctl, one(self.module_cc) is used for receiving
        commands sent from other modules, another one (self._cc)
        is used to send the command from Bindctl or other tools
        to proper modules.'''
        self._cc = isc.cc.Session()
        self._module_cc = isc.config.ModuleCCSession(SPECFILE_LOCATION,
                                              self.config_handler,
                                              self.command_handler)
        self._module_name = self._module_cc.get_module_spec().get_module_name()
        self._cmdctl_config_data = self._module_cc.get_full_config()
        self._module_cc.start()

    def _accounts_file_check(self, filepath):
        ''' Check whether the accounts file is valid, each row
        should be a list with 3 items.'''
        csvfile = None
        errstr = None
        try:
            csvfile = open(filepath)
            reader = csv.reader(csvfile)
            for row in reader:
                a = (row[0], row[1], row[2])
        except (IOError, IndexError) as e:
            errstr = 'Invalid accounts file: ' + str(e)
        finally:
            if csvfile:
                csvfile.close()

        return errstr

    def _config_data_check(self, new_config):
        ''' Check whether the new config data is valid or
        not. '''
        errstr = None
        for key in new_config:
            if key == 'version':
                continue
            elif key in ['key_file', 'cert_file']:
                #TODO, only check whether the file exist,
                # further check need to be done: eg. whether
                # the private/certificate is valid.
                path = new_config[key]
                if not os.path.exists(path):
                    errstr = "the file doesn't exist: " + path
            elif key == 'accounts_file':
                errstr = self._accounts_file_check(new_config[key])
            else:
                errstr = 'unknown config item: ' + key

            if errstr != None:
                logger.error(CMDCTL_BAD_CONFIG_DATA, errstr);
                return ccsession.create_answer(1, errstr)

        return ccsession.create_answer(0)

    def config_handler(self, new_config):
        answer = self._config_data_check(new_config)
        rcode, val = ccsession.parse_answer(answer)
        if rcode != 0:
            return answer

        with self._lock:
            for key in new_config:
                if key in self._cmdctl_config_data:
                    self._cmdctl_config_data[key] = new_config[key]
        return answer

    def command_handler(self, command, args):
        answer = ccsession.create_answer(0)
        if command == ccsession.COMMAND_MODULE_SPECIFICATION_UPDATE:
            # The 'value' of a specification update can be either
            # a specification, or None. In the first case, simply
            # set it. If it is None, delete the module if it is
            # known.
            with self._lock:
                if args[1] is None:
                    if args[0] in self.modules_spec:
                        del self.modules_spec[args[0]]
                    else:
                        answer = ccsession.create_answer(1,
                                                         'No such module: ' +
                                                         args[0])
                else:
                    self.modules_spec[args[0]] = args[1]

        elif command == ccsession.COMMAND_SHUTDOWN:
            #When cmdctl get 'shutdown' command from boss,
            #shutdown the outer httpserver.
            self._module_cc.send_stopping()
            self._httpserver.shutdown()
            self._serving = False

        elif command == 'print_settings':
            answer = ccsession.create_answer(0, self._cmdctl_config_data)
        else:
            answer = ccsession.create_answer(1, 'unknown command: ' + command)

        return answer

    def _start_msg_handle_thread(self):
        ''' Start one thread to handle received message from msgq.'''
        td = threading.Thread(target=self._handle_msg_from_msgq)
        td.daemon = True
        td.start()

    def _handle_msg_from_msgq(self):
        '''Process all the received commands with module session. '''
        while self._serving:
            self._module_cc.check_command(False)

    def _parse_command_result(self, rcode, reply):
        '''Ignore the error reason when command rcode isn't 0, '''
        if rcode != 0:
            return {}
        return reply

    def _get_config_data_from_config_manager(self):
        '''Get config data for all modules from configmanager '''
        rcode, reply = self.send_command('ConfigManager', ccsession.COMMAND_GET_CONFIG)
        return self._parse_command_result(rcode, reply)

    def _update_config_data(self, module_name, command_name):
        '''Get lastest config data for all modules from configmanager '''
        if module_name == 'ConfigManager' and command_name == ccsession.COMMAND_SET_CONFIG:
            data = self._get_config_data_from_config_manager()
            with self._lock:
                self._config_data = data

    def get_config_data(self):
        with self._lock:
            data = self._config_data
        return data

    def get_modules_spec(self):
        with self._lock:
            spec = self.modules_spec
        return spec

    def _get_modules_specification(self):
        '''Get all the modules' specification files. '''
        rcode, reply = self.send_command('ConfigManager', ccsession.COMMAND_GET_MODULE_SPEC)
        return self._parse_command_result(rcode, reply)

    def send_command_with_check(self, module_name, command_name, params = None):
        '''Before send the command to modules, check if module_name, command_name
        parameters are legal according the spec file of the module.
        Return rcode, dict. TODO, the rcode should be defined properly.
        rcode = 0: dict is the correct returned value.
        rcode > 0: dict is : { 'error' : 'error reason' }
        '''
        # core module ConfigManager does not have a specification file
        if module_name == 'ConfigManager':
            return self.send_command(module_name, command_name, params)

        specs = self.get_modules_spec()
        if module_name not in specs.keys():
            return 1, {'error' : 'unknown module'}

        spec_obj = isc.config.module_spec.ModuleSpec(specs[module_name], False)
        errors = []
        if not spec_obj.validate_command(command_name, params, errors):
            return 1, {'error': errors[0]}

        return self.send_command(module_name, command_name, params)

    def send_command(self, module_name, command_name, params = None):
        '''Send the command from bindctl to proper module. '''
        errstr = 'unknown error'
        answer = None
        logger.debug(DBG_CMDCTL_MESSAGING, CMDCTL_SEND_COMMAND,
                     command_name, module_name)

        if module_name == self._module_name:
            # Process the command sent to cmdctl directly.
            answer = self.command_handler(command_name, params)
        else:
            msg = ccsession.create_command(command_name, params)
            seq = self._cc.group_sendmsg(msg, module_name)
            logger.debug(DBG_CMDCTL_MESSAGING, CMDCTL_COMMAND_SENT,
                         command_name, module_name)
            #TODO, it may be blocked, msqg need to add a new interface waiting in timeout.
            try:
                answer, env = self._cc.group_recvmsg(False, seq)
            except isc.cc.session.SessionTimeout:
                errstr = "Module '%s' not responding" % module_name

        if answer:
            try:
                rcode, arg = ccsession.parse_answer(answer)
                if rcode == 0:
                    self._update_config_data(module_name, command_name)
                    if arg != None:
                        return rcode, arg
                    else:
                        return rcode, {}
                else:
                    errstr = str(answer['result'][1])
            except ccsession.ModuleCCSessionError as mcse:
                errstr = str("Error in ccsession answer:") + str(mcse)

        logger.error(CMDCTL_COMMAND_ERROR, command_name, module_name, errstr)
        return 1, {'error': errstr}

    def get_cmdctl_config_data(self):
        ''' If running in source code tree, use keyfile, certificate
        and user accounts file in source code. '''
        if "B10_FROM_SOURCE" in os.environ:
            sysconf_path = os.environ["B10_FROM_SOURCE"] + "/src/bin/cmdctl/"
            accountsfile  = sysconf_path + "cmdctl-accounts.csv"
            keyfile = sysconf_path + "cmdctl-keyfile.pem"
            certfile = sysconf_path + "cmdctl-certfile.pem"
            return (keyfile, certfile, accountsfile)

        with self._lock:
            keyfile = self._cmdctl_config_data.get('key_file')
            certfile = self._cmdctl_config_data.get('cert_file')
            accountsfile = self._cmdctl_config_data.get('accounts_file')

        return (keyfile, certfile, accountsfile)

class SecureHTTPServer(socketserver_mixin.NoPollMixIn,
                       socketserver.ThreadingMixIn,
                       http.server.HTTPServer):
    '''Make the server address can be reused.'''
    allow_reuse_address = True

    def __init__(self, server_address, RequestHandlerClass,
                 CommandControlClass,
                 idle_timeout = 1200, verbose = False):
        '''idle_timeout: the max idle time for login'''
        socketserver_mixin.NoPollMixIn.__init__(self)
        try:
            http.server.HTTPServer.__init__(self, server_address, RequestHandlerClass)
            logger.debug(DBG_CMDCTL_MESSAGING, CMDCTL_STARTED,
                         server_address[0], server_address[1])
        except socket.error as err:
            raise CmdctlException("Error creating server, because: %s \n" % str(err))

        self.user_sessions = {}
        self.idle_timeout = idle_timeout
        self.cmdctl = CommandControlClass(self, verbose)
        self._verbose = verbose
        self._lock = threading.Lock()
        self._user_infos = {}
        self._accounts_file = None

    def _create_user_info(self, accounts_file):
        '''Read all user's name and its' salt, hashed password
        from accounts file.'''
        if (self._accounts_file == accounts_file) and (len(self._user_infos) > 0):
            return

        with self._lock:
            self._user_infos = {}
            csvfile = None
            try:
                csvfile = open(accounts_file)
                reader = csv.reader(csvfile)
                for row in reader:
                    self._user_infos[row[0]] = [row[1], row[2]]
            except (IOError, IndexError) as e:
                logger.error(CMDCTL_USER_DATABASE_READ_ERROR,
                             accounts_file, e)
            finally:
                if csvfile:
                    csvfile.close()

        self._accounts_file = accounts_file
        if len(self._user_infos) == 0:
            logger.error(CMDCTL_NO_USER_ENTRIES_READ)

    def get_user_info(self, username):
        '''Get user's salt and hashed string. If the user
        doesn't exist, return None, or else, the list
        [salt, hashed password] will be returned.'''
        with self._lock:
            info = self._user_infos.get(username)
        return info

    def save_user_session_id(self, session_id):
        ''' Record user's id and login time. '''
        self.user_sessions[session_id] = time.time()

    def _check_key_and_cert(self, key, cert):
        # TODO, check the content of key/certificate file
        if not os.path.exists(key):
            raise CmdctlException("key file '%s' doesn't exist " % key)

        if not os.path.exists(cert):
            raise CmdctlException("certificate file '%s' doesn't exist " % cert)

    def _wrap_socket_in_ssl_context(self, sock, key, cert):
        try:
            self._check_key_and_cert(key, cert)
            ssl_sock = ssl.wrap_socket(sock,
                                      server_side = True,
                                      certfile = cert,
                                      keyfile = key,
                                      ssl_version = ssl.PROTOCOL_SSLv23)
            return ssl_sock
        except (ssl.SSLError, CmdctlException) as err :
            logger.error(CMDCTL_SSL_SETUP_FAILURE_USER_DENIED, err)
            self.close_request(sock)
            # raise socket error to finish the request
            raise socket.error

    def get_request(self):
        '''Get client request socket and wrap it in SSL context. '''
        key, cert, account_file = self.cmdctl.get_cmdctl_config_data()
        self._create_user_info(account_file)
        newsocket, fromaddr = self.socket.accept()
        ssl_sock = self._wrap_socket_in_ssl_context(newsocket, key, cert)
        return (ssl_sock, fromaddr)

    def get_reply_data_for_GET(self, id, module):
        '''Currently only support the following three url GET request '''
        rcode, reply = http.client.NO_CONTENT, []
        if not module:
            if id == CONFIG_DATA_URL:
                rcode, reply = http.client.OK, self.cmdctl.get_config_data()
            elif id == MODULE_SPEC_URL:
                rcode, reply = http.client.OK, self.cmdctl.get_modules_spec()

        return rcode, reply

    def send_command_to_module(self, module_name, command_name, params):
        return self.cmdctl.send_command_with_check(module_name, command_name, params)

httpd = None

def signal_handler(signal, frame):
    if httpd:
        httpd.shutdown()
    sys.exit(0)

def set_signal_handler():
    signal.signal(signal.SIGTERM, signal_handler)
    signal.signal(signal.SIGINT, signal_handler)

def run(addr = 'localhost', port = 8080, idle_timeout = 1200, verbose = False):
    ''' Start cmdctl as one https server. '''
    httpd = SecureHTTPServer((addr, port), SecureHTTPRequestHandler,
                             CommandControl, idle_timeout, verbose)

    httpd.serve_forever()

def check_port(option, opt_str, value, parser):
    try:
        parser.values.port = isc.net.parse.port_parse(value)
    except ValueError as e:
        raise OptionValueError(str(e))

def check_addr(option, opt_str, value, parser):
    try:
        isc.net.parse.addr_parse(value)
        parser.values.addr = value
    except ValueError as e:
        raise OptionValueError(str(e))

def set_cmd_options(parser):
    parser.add_option('-p', '--port', dest = 'port', type = 'int',
            action = 'callback', callback=check_port,
            default = '8080', help = 'port cmdctl will use')

    parser.add_option('-a', '--address', dest = 'addr', type = 'string',
            action = 'callback', callback=check_addr,
            default = '127.0.0.1', help = 'IP address cmdctl will use')

    parser.add_option('-i', '--idle-timeout', dest = 'idle_timeout', type = 'int',
            default = '1200', help = 'login idle time out')

    parser.add_option("-v", "--verbose", dest="verbose", action="store_true", default=False,
            help="display more about what is going on")

if __name__ == '__main__':
    set_signal_handler()
    parser = OptionParser(version = __version__)
    set_cmd_options(parser)
    (options, args) = parser.parse_args()
    result = 1                  # in case of failure
    try:
        if options.verbose:
            logger.set_severity("DEBUG", 99)
        run(options.addr, options.port, options.idle_timeout, options.verbose)
        result = 0
    except isc.cc.SessionError as err:
        logger.fatal(CMDCTL_CC_SESSION_ERROR, err)
    except isc.cc.SessionTimeout:
        logger.fatal(CMDCTL_CC_SESSION_TIMEOUT)
    except KeyboardInterrupt:
        logger.info(CMDCTL_STOPPED_BY_KEYBOARD)
    except CmdctlException as err:
        logger.fatal(CMDCTL_UNCAUGHT_EXCEPTION, err);

    if httpd:
        httpd.shutdown()

    sys.exit(result)
