text: # Copyright 2015 - 2016 OpenMarket Ltd
  # Copyright 2017 Vector Creations Ltd
  #
  # 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.
  import logging
  import random
  from typing import TYPE_CHECKING, List, Optional, Tuple
  
  from twisted.web.server import Request
  
  import synapse
  import synapse.api.auth
  import synapse.types
  from synapse.api.constants import APP_SERVICE_REGISTRATION_TYPE, LoginType
  from synapse.api.errors import (
      Codes,
      InteractiveAuthIncompleteError,
      SynapseError,
      ThreepidValidationError,
      UnrecognizedRequestError,
  )
  from synapse.api.ratelimiting import Ratelimiter
  from synapse.config import ConfigError
  from synapse.config.emailconfig import ThreepidBehaviour
  from synapse.config.homeserver import HomeServerConfig
  from synapse.config.ratelimiting import FederationRateLimitConfig
  from synapse.config.server import is_threepid_reserved
  from synapse.handlers.auth import AuthHandler
  from synapse.handlers.ui_auth import UIAuthSessionDataConstants
  from synapse.http.server import HttpServer, finish_request, respond_with_html
  from synapse.http.servlet import (
      RestServlet,
      assert_params_in_dict,
      parse_boolean,
      parse_json_object_from_request,
      parse_string,
  )
  from synapse.http.site import SynapseRequest
  from synapse.metrics import threepid_send_requests
  from synapse.push.mailer import Mailer
  from synapse.types import JsonDict
  from synapse.util.msisdn import phone_number_to_msisdn
  from synapse.util.ratelimitutils import FederationRateLimiter
  from synapse.util.stringutils import assert_valid_client_secret, random_string
  from synapse.util.threepids import (
      canonicalise_email,
      check_3pid_allowed,
      validate_email,
  )
  
  from ._base import client_patterns, interactive_auth_handler
  
  if TYPE_CHECKING:
      from synapse.server import HomeServer
  
  logger = logging.getLogger(__name__)
  
  
  class EmailRegisterRequestTokenRestServlet(RestServlet):
      PATTERNS = client_patterns("/register/email/requestToken$")
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
          self.hs = hs
          self.identity_handler = hs.get_identity_handler()
          self.config = hs.config
  
          if self.hs.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
              self.mailer = Mailer(
                  hs=self.hs,
                  app_name=self.config.email.email_app_name,
                  template_html=self.config.email.email_registration_template_html,
                  template_text=self.config.email.email_registration_template_text,
              )
  
      async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
          if self.hs.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
              if (
                  self.hs.config.email.local_threepid_handling_disabled_due_to_email_config
              ):
                  logger.warning(
                      "Email registration has been disabled due to lack of email config"
                  )
              raise SynapseError(
                  400, "Email-based registration has been disabled on this server"
              )
          body = parse_json_object_from_request(request)
  
          assert_params_in_dict(body, ["client_secret", "email", "send_attempt"])
  
          # Extract params from body
          client_secret = body["client_secret"]
          assert_valid_client_secret(client_secret)
  
          # For emails, canonicalise the address.
          # We store all email addresses canonicalised in the DB.
          # (See on_POST in EmailThreepidRequestTokenRestServlet
          # in synapse/rest/client/account.py)
          try:
              email = validate_email(body["email"])
          except ValueError as e:
              raise SynapseError(400, str(e))
          send_attempt = body["send_attempt"]
          next_link = body.get("next_link")  # Optional param
  
          if not check_3pid_allowed(self.hs, "email", email):
              raise SynapseError(
                  403,
                  "Your email domain is not authorized to register on this server",
                  Codes.THREEPID_DENIED,
              )
  
          await self.identity_handler.ratelimit_request_token_requests(
              request, "email", email
          )
  
          existing_user_id = await self.hs.get_datastore().get_user_id_by_threepid(
              "email", email
          )
  
          if existing_user_id is not None:
              if self.hs.config.server.request_token_inhibit_3pid_errors:
                  # Make the client think the operation succeeded. See the rationale in the
                  # comments for request_token_inhibit_3pid_errors.
                  # Also wait for some random amount of time between 100ms and 1s to make it
                  # look like we did something.
                  await self.hs.get_clock().sleep(random.randint(1, 10) / 10)
                  return 200, {"sid": random_string(16)}
  
              raise SynapseError(400, "Email is already in use", Codes.THREEPID_IN_USE)
  
          if self.config.email.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
              assert self.hs.config.registration.account_threepid_delegate_email
  
              # Have the configured identity server handle the request
              ret = await self.identity_handler.requestEmailToken(
                  self.hs.config.registration.account_threepid_delegate_email,
                  email,
                  client_secret,
                  send_attempt,
                  next_link,
              )
          else:
              # Send registration emails from Synapse
              sid = await self.identity_handler.send_threepid_validation(
                  email,
                  client_secret,
                  send_attempt,
                  self.mailer.send_registration_mail,
                  next_link,
              )
  
              # Wrap the session id in a JSON object
              ret = {"sid": sid}
  
          threepid_send_requests.labels(type="email", reason="register").observe(
              send_attempt
          )
  
          return 200, ret
  
  
  class MsisdnRegisterRequestTokenRestServlet(RestServlet):
      PATTERNS = client_patterns("/register/msisdn/requestToken$")
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
          self.hs = hs
          self.identity_handler = hs.get_identity_handler()
  
      async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
          body = parse_json_object_from_request(request)
  
          assert_params_in_dict(
              body, ["client_secret", "country", "phone_number", "send_attempt"]
          )
          client_secret = body["client_secret"]
          assert_valid_client_secret(client_secret)
          country = body["country"]
          phone_number = body["phone_number"]
          send_attempt = body["send_attempt"]
          next_link = body.get("next_link")  # Optional param
  
          msisdn = phone_number_to_msisdn(country, phone_number)
  
          if not check_3pid_allowed(self.hs, "msisdn", msisdn):
              raise SynapseError(
                  403,
                  "Phone numbers are not authorized to register on this server",
                  Codes.THREEPID_DENIED,
              )
  
          await self.identity_handler.ratelimit_request_token_requests(
              request, "msisdn", msisdn
          )
  
          existing_user_id = await self.hs.get_datastore().get_user_id_by_threepid(
              "msisdn", msisdn
          )
  
          if existing_user_id is not None:
              if self.hs.config.server.request_token_inhibit_3pid_errors:
                  # Make the client think the operation succeeded. See the rationale in the
                  # comments for request_token_inhibit_3pid_errors.
                  # Also wait for some random amount of time between 100ms and 1s to make it
                  # look like we did something.
                  await self.hs.get_clock().sleep(random.randint(1, 10) / 10)
                  return 200, {"sid": random_string(16)}
  
              raise SynapseError(
                  400, "Phone number is already in use", Codes.THREEPID_IN_USE
              )
  
          if not self.hs.config.registration.account_threepid_delegate_msisdn:
              logger.warning(
                  "No upstream msisdn account_threepid_delegate configured on the server to "
                  "handle this request"
              )
              raise SynapseError(
                  400, "Registration by phone number is not supported on this homeserver"
              )
  
          ret = await self.identity_handler.requestMsisdnToken(
              self.hs.config.registration.account_threepid_delegate_msisdn,
              country,
              phone_number,
              client_secret,
              send_attempt,
              next_link,
          )
  
          threepid_send_requests.labels(type="msisdn", reason="register").observe(
              send_attempt
          )
  
          return 200, ret
  
  
  class RegistrationSubmitTokenServlet(RestServlet):
      """Handles registration 3PID validation token submission"""
  
      PATTERNS = client_patterns(
          "/registration/(?P<medium>[^/]*)/submit_token$", releases=(), unstable=True
      )
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
          self.hs = hs
          self.auth = hs.get_auth()
          self.config = hs.config
          self.clock = hs.get_clock()
          self.store = hs.get_datastore()
  
          if self.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
              self._failure_email_template = (
                  self.config.email.email_registration_template_failure_html
              )
  
      async def on_GET(self, request: Request, medium: str) -> None:
          if medium != "email":
              raise SynapseError(
                  400, "This medium is currently not supported for registration"
              )
          if self.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
              if self.config.email.local_threepid_handling_disabled_due_to_email_config:
                  logger.warning(
                      "User registration via email has been disabled due to lack of email config"
                  )
              raise SynapseError(
                  400, "Email-based registration is disabled on this server"
              )
  
          sid = parse_string(request, "sid", required=True)
          client_secret = parse_string(request, "client_secret", required=True)
          assert_valid_client_secret(client_secret)
          token = parse_string(request, "token", required=True)
  
          # Attempt to validate a 3PID session
          try:
              # Mark the session as valid
              next_link = await self.store.validate_threepid_session(
                  sid, client_secret, token, self.clock.time_msec()
              )
  
              # Perform a 302 redirect if next_link is set
              if next_link:
                  if next_link.startswith("file:///"):
                      logger.warning(
                          "Not redirecting to next_link as it is a local file: address"
                      )
                  else:
                      request.setResponseCode(302)
                      request.setHeader("Location", next_link)
                      finish_request(request)
                      return None
  
              # Otherwise show the success template
              html = self.config.email.email_registration_template_success_html_content
              status_code = 200
          except ThreepidValidationError as e:
              status_code = e.code
  
              # Show a failure page with a reason
              template_vars = {"failure_reason": e.msg}
              html = self._failure_email_template.render(**template_vars)
  
          respond_with_html(request, status_code, html)
  
  
  class UsernameAvailabilityRestServlet(RestServlet):
      PATTERNS = client_patterns("/register/available")
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
          self.hs = hs
          self.registration_handler = hs.get_registration_handler()
          self.ratelimiter = FederationRateLimiter(
              hs.get_clock(),
              FederationRateLimitConfig(
                  # Time window of 2s
                  window_size=2000,
                  # Artificially delay requests if rate > sleep_limit/window_size
                  sleep_limit=1,
                  # Amount of artificial delay to apply
                  sleep_delay=1000,
                  # Error with 429 if more than reject_limit requests are queued
                  reject_limit=1,
                  # Allow 1 request at a time
                  concurrent=1,
              ),
          )
  
      async def on_GET(self, request: Request) -> Tuple[int, JsonDict]:
          if not self.hs.config.registration.enable_registration:
              raise SynapseError(
                  403, "Registration has been disabled", errcode=Codes.FORBIDDEN
              )
  
          ip = request.getClientIP()
          with self.ratelimiter.ratelimit(ip) as wait_deferred:
              await wait_deferred
  
              username = parse_string(request, "username", required=True)
  
              await self.registration_handler.check_username(username)
  
              return 200, {"available": True}
  
  
  class RegistrationTokenValidityRestServlet(RestServlet):
      """Check the validity of a registration token.
  
      Example:
  
          GET /_matrix/client/unstable/org.matrix.msc3231/register/org.matrix.msc3231.login.registration_token/validity?token=abcd
  
          200 OK
  
          {
              "valid": true
          }
      """
  
      PATTERNS = client_patterns(
          f"/org.matrix.msc3231/register/{LoginType.REGISTRATION_TOKEN}/validity",
          releases=(),
          unstable=True,
      )
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
          self.hs = hs
          self.store = hs.get_datastore()
          self.ratelimiter = Ratelimiter(
              store=self.store,
              clock=hs.get_clock(),
              rate_hz=hs.config.ratelimiting.rc_registration_token_validity.per_second,
              burst_count=hs.config.ratelimiting.rc_registration_token_validity.burst_count,
          )
  
      async def on_GET(self, request: Request) -> Tuple[int, JsonDict]:
          await self.ratelimiter.ratelimit(None, (request.getClientIP(),))
  
          if not self.hs.config.registration.enable_registration:
              raise SynapseError(
                  403, "Registration has been disabled", errcode=Codes.FORBIDDEN
              )
  
          token = parse_string(request, "token", required=True)
          valid = await self.store.registration_token_is_valid(token)
  
          return 200, {"valid": valid}
  
  
  class RegisterRestServlet(RestServlet):
      PATTERNS = client_patterns("/register$")
  
      def __init__(self, hs: "HomeServer"):
          super().__init__()
  
          self.hs = hs
          self.auth = hs.get_auth()
          self.store = hs.get_datastore()
          self.auth_handler = hs.get_auth_handler()
          self.registration_handler = hs.get_registration_handler()
          self.identity_handler = hs.get_identity_handler()
          self.room_member_handler = hs.get_room_member_handler()
          self.macaroon_gen = hs.get_macaroon_generator()
          self.ratelimiter = hs.get_registration_ratelimiter()
          self.password_policy_handler = hs.get_password_policy_handler()
          self.clock = hs.get_clock()
          self._registration_enabled = self.hs.config.registration.enable_registration
          self._msc2918_enabled = (
              hs.config.registration.refreshable_access_token_lifetime is not None
          )
  
          self._registration_flows = _calculate_registration_flows(
              hs.config, self.auth_handler
          )
  
      @interactive_auth_handler
      async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
          body = parse_json_object_from_request(request)
  
          client_addr = request.getClientIP()
  
          await self.ratelimiter.ratelimit(None, client_addr, update=False)
  
          kind = parse_string(request, "kind", default="user")
  
          if kind == "guest":
              ret = await self._do_guest_registration(body, address=client_addr)
              return ret
          elif kind != "user":
              raise UnrecognizedRequestError(
                  f"Do not understand membership kind: {kind}",
              )
  
          if self._msc2918_enabled:
              # Check if this registration should also issue a refresh token, as
              # per MSC2918
              should_issue_refresh_token = parse_boolean(
                  request, name="org.matrix.msc2918.refresh_token", default=False
              )
          else:
              should_issue_refresh_token = False
  
          # Pull out the provided username and do basic sanity checks early since
          # the auth layer will store these in sessions.
          desired_username = None
          if "username" in body:
              if not isinstance(body["username"], str) or len(body["username"]) > 512:
                  raise SynapseError(400, "Invalid username")
              desired_username = body["username"]
  
          # fork off as soon as possible for ASes which have completely
          # different registration flows to normal users
  
          # == Application Service Registration ==
          if body.get("type") == APP_SERVICE_REGISTRATION_TYPE:
              if not self.auth.has_access_token(request):
                  raise SynapseError(
                      400,
                      "Appservice token must be provided when using a type of m.login.application_service",
                  )
  
              # Verify the AS
              self.auth.get_appservice_by_req(request)
  
              # Set the desired user according to the AS API (which uses the
              # 'user' key not 'username'). Since this is a new addition, we'll
              # fallback to 'username' if they gave one.
              desired_username = body.get("user", desired_username)
  
              # XXX we should check that desired_username is valid. Currently
              # we give appservices carte blanche for any insanity in mxids,
              # because the IRC bridges rely on being able to register stupid
              # IDs.
  
              access_token = self.auth.get_access_token_from_request(request)
  
              if not isinstance(desired_username, str):
                  raise SynapseError(400, "Desired Username is missing or not a string")
  
              result = await self._do_appservice_registration(
                  desired_username,
                  access_token,
                  body,
                  should_issue_refresh_token=should_issue_refresh_token,
              )
  
              return 200, result
          elif self.auth.has_access_token(request):
              raise SynapseError(
                  400,
                  "An access token should not be provided on requests to /register (except if type is m.login.application_service)",
              )
  
          # == Normal User Registration == (everyone else)
          if not self._registration_enabled:
              raise SynapseError(403, "Registration has been disabled", Codes.FORBIDDEN)
  
          # For regular registration, convert the provided username to lowercase
          # before attempting to register it. This should mean that people who try
          # to register with upper-case in their usernames don't get a nasty surprise.
          #
          # Note that we treat usernames case-insensitively in login, so they are
          # free to carry on imagining that their username is CrAzYh4cKeR if that
          # keeps them happy.
          if desired_username is not None:
              desired_username = desired_username.lower()
  
          # Check if this account is upgrading from a guest account.
          guest_access_token = body.get("guest_access_token", None)
  
          # Pull out the provided password and do basic sanity checks early.
          #
          # Note that we remove the password from the body since the auth layer
          # will store the body in the session and we don't want a plaintext
          # password store there.
          password = body.pop("password", None)
          if password is not None:
              if not isinstance(password, str) or len(password) > 512:
                  raise SynapseError(400, "Invalid password")
              self.password_policy_handler.validate_password(password)
  
          if "initial_device_display_name" in body and password is None:
              # ignore 'initial_device_display_name' if sent without
              # a password to work around a client bug where it sent
              # the 'initial_device_display_name' param alone, wiping out
              # the original registration params
              logger.warning("Ignoring initial_device_display_name without password")
              del body["initial_device_display_name"]
  
          session_id = self.auth_handler.get_session_id(body)
          registered_user_id = None
          password_hash = None
          if session_id:
              # if we get a registered user id out of here, it means we previously
              # registered a user for this session, so we could just return the
              # user here. We carry on and go through the auth checks though,
              # for paranoia.
              registered_user_id = await self.auth_handler.get_session_data(
                  session_id, UIAuthSessionDataConstants.REGISTERED_USER_ID, None
              )
              # Extract the previously-hashed password from the session.
              password_hash = await self.auth_handler.get_session_data(
                  session_id, UIAuthSessionDataConstants.PASSWORD_HASH, None
              )
  
          # Ensure that the username is valid.
          if desired_username is not None:
              await self.registration_handler.check_username(
                  desired_username,
                  guest_access_token=guest_access_token,
                  assigned_user_id=registered_user_id,
              )
  
          # Check if the user-interactive authentication flows are complete, if
          # not this will raise a user-interactive auth error.
          try:
              auth_result, params, session_id = await self.auth_handler.check_ui_auth(
                  self._registration_flows,
                  request,
                  body,
                  "register a new account",
              )
          except InteractiveAuthIncompleteError as e:
              # The user needs to provide more steps to complete auth.
              #
              # Hash the password and store it with the session since the client
              # is not required to provide the password again.
              #
              # If a password hash was previously stored we will not attempt to
              # re-hash and store it for efficiency. This assumes the password
              # does not change throughout the authentication flow, but this
              # should be fine since the data is meant to be consistent.
              if not password_hash and password:
                  password_hash = await self.auth_handler.hash(password)
                  await self.auth_handler.set_session_data(
                      e.session_id,
                      UIAuthSessionDataConstants.PASSWORD_HASH,
                      password_hash,
                  )
              raise
  
          # Check that we're not trying to register a denied 3pid.
          #
          # the user-facing checks will probably already have happened in
          # /register/email/requestToken when we requested a 3pid, but that's not
          # guaranteed.
          if auth_result:
              for login_type in [LoginType.EMAIL_IDENTITY, LoginType.MSISDN]:
                  if login_type in auth_result:
                      medium = auth_result[login_type]["medium"]
                      address = auth_result[login_type]["address"]
  
                      if not check_3pid_allowed(self.hs, medium, address):
                          raise SynapseError(
                              403,
                              "Third party identifiers (email/phone numbers)"
                              + " are not authorized on this server",
                              Codes.THREEPID_DENIED,
                          )
  
          if registered_user_id is not None:
              logger.info(
                  "Already registered user ID %r for this session", registered_user_id
              )
              # don't re-register the threepids
              registered = False
          else:
              # If we have a password in this request, prefer it. Otherwise, there
              # might be a password hash from an earlier request.
              if password:
                  password_hash = await self.auth_handler.hash(password)
              if not password_hash:
                  raise SynapseError(400, "Missing params: password", Codes.MISSING_PARAM)
  
              desired_username = params.get("username", None)
              guest_access_token = params.get("guest_access_token", None)
  
              if desired_username is not None:
                  desired_username = desired_username.lower()
  
              threepid = None
              if auth_result:
                  threepid = auth_result.get(LoginType.EMAIL_IDENTITY)
  
                  # Also check that we're not trying to register a 3pid that's already
                  # been registered.
                  #
                  # This has probably happened in /register/email/requestToken as well,
                  # but if a user hits this endpoint twice then clicks on each link from
                  # the two activation emails, they would register the same 3pid twice.
                  for login_type in [LoginType.EMAIL_IDENTITY, LoginType.MSISDN]:
                      if login_type in auth_result:
                          medium = auth_result[login_type]["medium"]
                          address = auth_result[login_type]["address"]
                          # For emails, canonicalise the address.
                          # We store all email addresses canonicalised in the DB.
                          # (See on_POST in EmailThreepidRequestTokenRestServlet
                          # in synapse/rest/client/account.py)
                          if medium == "email":
                              try:
                                  address = canonicalise_email(address)
                              except ValueError as e:
                                  raise SynapseError(400, str(e))
  
                          existing_user_id = await self.store.get_user_id_by_threepid(
                              medium, address
                          )
  
                          if existing_user_id is not None:
                              raise SynapseError(
                                  400,
                                  "%s is already in use" % medium,
                                  Codes.THREEPID_IN_USE,
                              )
  
              entries = await self.store.get_user_agents_ips_to_ui_auth_session(
                  session_id
              )
  
              registered_user_id = await self.registration_handler.register_user(
                  localpart=desired_username,
                  password_hash=password_hash,
                  guest_access_token=guest_access_token,
                  threepid=threepid,
                  address=client_addr,
                  user_agent_ips=entries,
              )
              # Necessary due to auth checks prior to the threepid being
              # written to the db
              if threepid:
                  if is_threepid_reserved(
                      self.hs.config.server.mau_limits_reserved_threepids, threepid
                  ):
                      await self.store.upsert_monthly_active_user(registered_user_id)
  
              # Remember that the user account has been registered (and the user
              # ID it was registered with, since it might not have been specified).
              await self.auth_handler.set_session_data(
                  session_id,
                  UIAuthSessionDataConstants.REGISTERED_USER_ID,
                  registered_user_id,
              )
  
              registered = True
  
          return_dict = await self._create_registration_details(
              registered_user_id,
              params,
              should_issue_refresh_token=should_issue_refresh_token,
          )
  
          if registered:
              # Check if a token was used to authenticate registration
              registration_token = await self.auth_handler.get_session_data(
                  session_id,
                  UIAuthSessionDataConstants.REGISTRATION_TOKEN,
              )
              if registration_token:
                  # Increment the `completed` counter for the token
                  await self.store.use_registration_token(registration_token)
                  # Indicate that the token has been successfully used so that
                  # pending is not decremented again when expiring old UIA sessions.
                  await self.store.mark_ui_auth_stage_complete(
                      session_id,
                      LoginType.REGISTRATION_TOKEN,
                      True,
                  )
  
              await self.registration_handler.post_registration_actions(
                  user_id=registered_user_id,
                  auth_result=auth_result,
                  access_token=return_dict.get("access_token"),
              )
  
          return 200, return_dict
  
      async def _do_appservice_registration(
          self,
          username: str,
          as_token: str,
          body: JsonDict,
          should_issue_refresh_token: bool = False,
      ) -> JsonDict:
          user_id = await self.registration_handler.appservice_register(
              username, as_token
          )
          return await self._create_registration_details(
              user_id,
              body,
              is_appservice_ghost=True,
              should_issue_refresh_token=should_issue_refresh_token,
          )
  
      async def _create_registration_details(
          self,
          user_id: str,
          params: JsonDict,
          is_appservice_ghost: bool = False,
          should_issue_refresh_token: bool = False,
      ) -> JsonDict:
          """Complete registration of newly-registered user
  
          Allocates device_id if one was not given; also creates access_token.
  
          Args:
              user_id: full canonical @user:id
              params: registration parameters, from which we pull device_id,
                  initial_device_name and inhibit_login
              is_appservice_ghost
              should_issue_refresh_token: True if this registration should issue
                  a refresh token alongside the access token.
          Returns:
               dictionary for response from /register
          """
          result: JsonDict = {
              "user_id": user_id,
              "home_server": self.hs.hostname,
          }
          if not params.get("inhibit_login", False):
              device_id = params.get("device_id")
              initial_display_name = params.get("initial_device_display_name")
              (
                  device_id,
                  access_token,
                  valid_until_ms,
                  refresh_token,
              ) = await self.registration_handler.register_device(
                  user_id,
                  device_id,
                  initial_display_name,
                  is_guest=False,
                  is_appservice_ghost=is_appservice_ghost,
                  should_issue_refresh_token=should_issue_refresh_token,
              )
  
              result.update({"access_token": access_token, "device_id": device_id})
  
              if valid_until_ms is not None:
                  expires_in_ms = valid_until_ms - self.clock.time_msec()
                  result["expires_in_ms"] = expires_in_ms
  
              if refresh_token is not None:
                  result["refresh_token"] = refresh_token
  
          return result
  
      async def _do_guest_registration(
          self, params: JsonDict, address: Optional[str] = None
      ) -> Tuple[int, JsonDict]:
          if not self.hs.config.registration.allow_guest_access:
              raise SynapseError(403, "Guest access is disabled")
          user_id = await self.registration_handler.register_user(
              make_guest=True, address=address
          )
  
          # we don't allow guests to specify their own device_id, because
          # we have nowhere to store it.
          device_id = synapse.api.auth.GUEST_DEVICE_ID
          initial_display_name = params.get("initial_device_display_name")
          (
              device_id,
              access_token,
              valid_until_ms,
              refresh_token,
          ) = await self.registration_handler.register_device(
              user_id, device_id, initial_display_name, is_guest=True
          )
  
          result: JsonDict = {
              "user_id": user_id,
              "device_id": device_id,
              "access_token": access_token,
              "home_server": self.hs.hostname,
          }
  
          if valid_until_ms is not None:
              expires_in_ms = valid_until_ms - self.clock.time_msec()
              result["expires_in_ms"] = expires_in_ms
  
          if refresh_token is not None:
              result["refresh_token"] = refresh_token
  
          return 200, result
  
  
  def _calculate_registration_flows(
      config: HomeServerConfig, auth_handler: AuthHandler
  ) -> List[List[str]]:
      """Get a suitable flows list for registration
  
      Args:
          config: server configuration
          auth_handler: authorization handler
  
      Returns: a list of supported flows
      """
      # FIXME: need a better error than "no auth flow found" for scenarios
      # where we required 3PID for registration but the user didn't give one
      require_email = "email" in config.registration.registrations_require_3pid
      require_msisdn = "msisdn" in config.registration.registrations_require_3pid
  
      show_msisdn = True
      show_email = True
  
      if config.registration.disable_msisdn_registration:
          show_msisdn = False
          require_msisdn = False
  
      enabled_auth_types = auth_handler.get_enabled_auth_types()
      if LoginType.EMAIL_IDENTITY not in enabled_auth_types:
          show_email = False
          if require_email:
              raise ConfigError(
                  "Configuration requires email address at registration, but email "
                  "validation is not configured"
              )
  
      if LoginType.MSISDN not in enabled_auth_types:
          show_msisdn = False
          if require_msisdn:
              raise ConfigError(
                  "Configuration requires msisdn at registration, but msisdn "
                  "validation is not configured"
              )
  
      flows = []
  
      # only support 3PIDless registration if no 3PIDs are required
      if not require_email and not require_msisdn:
          # Add a dummy step here, otherwise if a client completes
          # recaptcha first we'll assume they were going for this flow
          # and complete the request, when they could have been trying to
          # complete one of the flows with email/msisdn auth.
          flows.append([LoginType.DUMMY])
  
      # only support the email-only flow if we don't require MSISDN 3PIDs
      if show_email and not require_msisdn:
          flows.append([LoginType.EMAIL_IDENTITY])
  
      # only support the MSISDN-only flow if we don't require email 3PIDs
      if show_msisdn and not require_email:
          flows.append([LoginType.MSISDN])
  
      if show_email and show_msisdn:
          # always let users provide both MSISDN & email
          flows.append([LoginType.MSISDN, LoginType.EMAIL_IDENTITY])
  
      # Prepend m.login.terms to all flows if we're requiring consent
      if config.consent.user_consent_at_registration:
          for flow in flows:
              flow.insert(0, LoginType.TERMS)
  
      # Prepend recaptcha to all flows if we're requiring captcha
      if config.captcha.enable_registration_captcha:
          for flow in flows:
              flow.insert(0, LoginType.RECAPTCHA)
  
      # Prepend registration token to all flows if we're requiring a token
      if config.registration.registration_requires_token:
          for flow in flows:
              flow.insert(0, LoginType.REGISTRATION_TOKEN)
  
      return flows
  
  
  def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
      EmailRegisterRequestTokenRestServlet(hs).register(http_server)
      MsisdnRegisterRequestTokenRestServlet(hs).register(http_server)
      UsernameAvailabilityRestServlet(hs).register(http_server)
      RegistrationSubmitTokenServlet(hs).register(http_server)
      RegistrationTokenValidityRestServlet(hs).register(http_server)
      RegisterRestServlet(hs).register(http_server)
  