lbry-sdk/lbrynet/lbrynet_daemon/auth/server.py

import logging
import urlparse

from decimal import Decimal
from zope.interface import implements
from twisted.web import server, resource
from twisted.internet import defer
from twisted.python.failure import Failure
from twisted.internet.error import ConnectionDone, ConnectionLost
from txjsonrpc import jsonrpclib

from lbrynet import conf
from lbrynet.core.Error import InvalidAuthenticationToken, InvalidHeaderError
from lbrynet.core import utils
from lbrynet.lbrynet_daemon.auth.util import APIKey, get_auth_message, jsonrpc_dumps_pretty
from lbrynet.lbrynet_daemon.auth.client import LBRY_SECRET

log = logging.getLogger(__name__)

EMPTY_PARAMS = [{}]


def default_decimal(obj):
    if isinstance(obj, Decimal):
        return float(obj)


class JSONRPCException(Exception):
    def __init__(self, err, code):
        self.faultCode = code
        self.err = err

    @property
    def faultString(self):
        try:
            return self.err.getTraceback()
        except AttributeError:
            return str(self.err)


class UnknownAPIMethodError(Exception):
    pass


class NotAllowedDuringStartupError(Exception):
    pass


def trap(err, *to_trap):
    err.trap(*to_trap)


class AuthorizedBase(object):
    def __init__(self):
        self.authorized_functions = []
        self.callable_methods = {}

        for methodname in dir(self):
            if methodname.startswith("jsonrpc_"):
                method = getattr(self, methodname)
                self.callable_methods.update({methodname.split("jsonrpc_")[1]: method})
                if hasattr(method, '_auth_required'):
                    self.authorized_functions.append(methodname.split("jsonrpc_")[1])

    @staticmethod
    def auth_required(f):
        f._auth_required = True
        return f


class AuthJSONRPCServer(AuthorizedBase):
    """Authorized JSONRPC server used as the base class for the LBRY API

    API methods are named with a leading "jsonrpc_"

    Decorators:

        @AuthJSONRPCServer.auth_required: this requires that the client
            include a valid hmac authentication token in their request

    Attributes:
        allowed_during_startup (list): list of api methods that are
            callable before the server has finished startup

        sessions (dict): dictionary of active session_id:
            lbrynet.lbrynet_daemon.auth.util.APIKey values

        authorized_functions (list): list of api methods that require authentication

        callable_methods (dict): dictionary of api_callable_name: method values

    """
    implements(resource.IResource)

    isLeaf = True
    OK = 200
    UNAUTHORIZED = 401
    # TODO: codes should follow jsonrpc spec: http://www.jsonrpc.org/specification#error_object
    NOT_FOUND = 8001
    FAILURE = 8002

    def __init__(self, use_authentication=None):
        AuthorizedBase.__init__(self)
        self._use_authentication = (
            use_authentication if use_authentication is not None else conf.settings['use_auth_http']
        )
        self.announced_startup = False
        self.allowed_during_startup = []
        self.sessions = {}

    def setup(self):
        return NotImplementedError()

    def _set_headers(self, request, data, update_secret=False):
        if conf.settings['allowed_origin']:
            request.setHeader("Access-Control-Allow-Origin", conf.settings['allowed_origin'])
        request.setHeader("Content-Type", "text/json")
        request.setHeader("Content-Length", str(len(data)))
        if update_secret:
            session_id = request.getSession().uid
            request.setHeader(LBRY_SECRET, self.sessions.get(session_id).secret)

    def _render_message(self, request, message):
        request.write(message)
        request.finish()

    def _render_error(self, failure, request, id_,
                      version=jsonrpclib.VERSION_2, response_code=FAILURE):
        # TODO: is it necessary to wrap the failure in a Failure? if not, merge this with next fn
        self._render_error_string(Failure(failure), request, id_, version, response_code)

    def _render_error_string(self, error_string, request, id_, version=jsonrpclib.VERSION_2,
                             response_code=FAILURE):
        err = JSONRPCException(error_string, response_code)
        fault = jsonrpc_dumps_pretty(err, id=id_, version=version)
        self._set_headers(request, fault)
        if response_code != AuthJSONRPCServer.FAILURE:
            request.setResponseCode(response_code)
        self._render_message(request, fault)

    def _handle_dropped_request(self, result, d, function_name):
        if not d.called:
            log.warning("Cancelling dropped api request %s", function_name)
            d.cancel()

    def render(self, request):
        time_in = utils.now()
        assert self._check_headers(request), InvalidHeaderError
        session = request.getSession()
        session_id = session.uid
        finished_deferred = request.notifyFinish()

        if self._use_authentication:
            # if this is a new session, send a new secret and set the expiration
            # otherwise, session.touch()
            if self._initialize_session(session_id):
                def expire_session():
                    self._unregister_user_session(session_id)

                session.startCheckingExpiration()
                session.notifyOnExpire(expire_session)
                message = "OK"
                request.setResponseCode(self.OK)
                self._set_headers(request, message, True)
                self._render_message(request, message)
                return server.NOT_DONE_YET
            else:
                session.touch()

        request.content.seek(0, 0)
        content = request.content.read()
        try:
            parsed = jsonrpclib.loads(content)
        except ValueError:
            log.warning("Unable to decode request json")
            self._render_error_string('Invalid JSON', request, None)
            return server.NOT_DONE_YET

        function_name = parsed.get('method')
        args = parsed.get('params', {})
        id_ = parsed.get('id')
        token = parsed.pop('hmac', None)
        version = self._get_jsonrpc_version(parsed.get('jsonrpc'), id_)

        reply_with_next_secret = False
        if self._use_authentication:
            if function_name in self.authorized_functions:
                try:
                    self._verify_token(session_id, parsed, token)
                except InvalidAuthenticationToken as err:
                    log.warning("API validation failed")
                    self._render_error(
                        err, request, id_, version=version,
                        response_code=AuthJSONRPCServer.UNAUTHORIZED)
                    return server.NOT_DONE_YET
                self._update_session_secret(session_id)
                reply_with_next_secret = True

        try:
            function = self._get_jsonrpc_method(function_name)
        except (UnknownAPIMethodError, NotAllowedDuringStartupError) as err:
            log.warning('Failed to get function %s: %s', function_name, err)
            self._render_error(err, request, version)
            return server.NOT_DONE_YET

        if args == EMPTY_PARAMS or args == []:
            d = defer.maybeDeferred(function)
        elif isinstance(args, dict):
            d = defer.maybeDeferred(function, **args)
        elif len(args) == 1 and isinstance(args[0], dict):
            # TODO: this is for backwards compatibility. Remove this once API and UI are updated
            # TODO: also delete EMPTY_PARAMS then
            d = defer.maybeDeferred(function, **args[0])
        else:
            # d = defer.maybeDeferred(function, *args)  # if we want to support positional args too
            raise ValueError('Args must be a dict')

        # finished_deferred will callback when the request is finished
        # and errback if something went wrong. If the errback is
        # called, cancel the deferred stack. This is to prevent
        # request.finish() from being called on a closed request.
        finished_deferred.addErrback(self._handle_dropped_request, d, function_name)

        d.addCallback(self._callback_render, request, id_, version, reply_with_next_secret)
        # TODO: don't trap RuntimeError, which is presently caught to
        # handle deferredLists that won't peacefully cancel, namely
        # get_lbry_files
        d.addErrback(trap, ConnectionDone, ConnectionLost, defer.CancelledError, RuntimeError)
        d.addErrback(log.fail(self._render_error, request, id_, version=version),
                     'Failed to process %s', function_name)
        d.addBoth(lambda _: log.debug("%s took %f",
                                      function_name,
                                      (utils.now() - time_in).total_seconds()))
        return server.NOT_DONE_YET

    def _register_user_session(self, session_id):
        """
        Add or update a HMAC secret for a session

        @param session_id:
        @return: secret
        """
        log.info("Register api session")
        token = APIKey.new(seed=session_id)
        self.sessions.update({session_id: token})

    def _unregister_user_session(self, session_id):
        log.info("Unregister API session")
        del self.sessions[session_id]

    def _check_headers(self, request):
        return (
            self._check_header_source(request, 'Origin') and
            self._check_header_source(request, 'Referer'))

    def _check_header_source(self, request, header):
        """Check if the source of the request is allowed based on the header value."""
        source = request.getHeader(header)
        if not self._check_source_of_request(source):
            log.warning("Attempted api call from invalid %s: %s", header, source)
            return False
        return True

    def _check_source_of_request(self, source):
        if source is None:
            return True
        if conf.settings['api_host'] == '0.0.0.0':
            return True
        server, port = self.get_server_port(source)
        return (
            server == conf.settings['api_host'] and
            port == conf.settings['api_port'])

    def get_server_port(self, origin):
        parsed = urlparse.urlparse(origin)
        server_port = parsed.netloc.split(':')
        assert len(server_port) <= 2
        if len(server_port) == 2:
            return server_port[0], int(server_port[1])
        else:
            return server_port[0], 80

    def _verify_method_is_callable(self, function_path):
        if function_path not in self.callable_methods:
            raise UnknownAPIMethodError(function_path)
        if not self.announced_startup:
            if function_path not in self.allowed_during_startup:
                raise NotAllowedDuringStartupError(function_path)

    def _get_jsonrpc_method(self, function_path):
        self._verify_method_is_callable(function_path)
        return self.callable_methods.get(function_path)

    def _initialize_session(self, session_id):
        if not self.sessions.get(session_id, False):
            self._register_user_session(session_id)
            return True
        return False

    def _verify_token(self, session_id, message, token):
        assert token is not None, InvalidAuthenticationToken
        to_auth = get_auth_message(message)
        api_key = self.sessions.get(session_id)
        assert api_key.compare_hmac(to_auth, token), InvalidAuthenticationToken

    def _update_session_secret(self, session_id):
        self.sessions.update({session_id: APIKey.new(name=session_id)})

    @staticmethod
    def _get_jsonrpc_version(version=None, id_=None):
        if version:
            return int(float(version))
        elif id_:
            return jsonrpclib.VERSION_1
        else:
            return jsonrpclib.VERSION_PRE1

    def _callback_render(self, result, request, id_, version, auth_required=False):
        result_for_return = result

        if version == jsonrpclib.VERSION_PRE1:
            if not isinstance(result, jsonrpclib.Fault):
                result_for_return = (result_for_return,)

        try:
            encoded_message = jsonrpc_dumps_pretty(
                result_for_return, id=id_, version=version, default=default_decimal)
            self._set_headers(request, encoded_message, auth_required)
            self._render_message(request, encoded_message)
        except Exception as err:
            log.exception("Failed to render API response: %s", result)
            self._render_error(err, request, id_, version)

    @staticmethod
    def _render_response(result):
        return defer.succeed(result)