Esempio n. 1
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def remote_user_jwt(request: HttpRequest) -> HttpResponse:
    subdomain = get_subdomain(request)
    try:
        key = settings.JWT_AUTH_KEYS[subdomain]["key"]
        algorithms = settings.JWT_AUTH_KEYS[subdomain]["algorithms"]
    except KeyError:
        raise JsonableError(_("Auth key for this subdomain not found."))

    try:
        json_web_token = request.POST["json_web_token"]
        options = {"verify_signature": True}
        payload = jwt.decode(json_web_token,
                             key,
                             algorithms=algorithms,
                             options=options)
    except KeyError:
        raise JsonableError(_("No JSON web token passed in request"))
    except jwt.InvalidTokenError:
        raise JsonableError(_("Bad JSON web token"))

    remote_user = payload.get("user", None)
    if remote_user is None:
        raise JsonableError(_("No user specified in JSON web token claims"))
    email_domain = payload.get("realm", None)
    if email_domain is None:
        raise JsonableError(
            _("No organization specified in JSON web token claims"))

    email = f"{remote_user}@{email_domain}"

    try:
        realm = get_realm(subdomain)
    except Realm.DoesNotExist:
        raise JsonableError(_("Wrong subdomain"))

    user_profile = authenticate(username=email,
                                realm=realm,
                                use_dummy_backend=True)
    if user_profile is None:
        result = ExternalAuthResult(data_dict={
            "email": email,
            "full_name": remote_user,
            "subdomain": realm.subdomain
        })
    else:
        assert isinstance(user_profile, UserProfile)
        result = ExternalAuthResult(user_profile=user_profile)

    return login_or_register_remote_user(request, result)
Esempio n. 2
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def load_subdomain_token(response: HttpResponse) -> ExternalAuthDataDict:
    assert isinstance(response, HttpResponseRedirect)
    token = response.url.rsplit('/', 1)[1]
    data = ExternalAuthResult(login_token=token,
                              delete_stored_data=False).data_dict
    assert data is not None
    return data
Esempio n. 3
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def log_into_subdomain(request: HttpRequest, token: str) -> HttpResponse:
    """Given a valid authentication token (generated by
    redirect_and_log_into_subdomain called on auth.zulip.example.com),
    call login_or_register_remote_user, passing all the authentication
    result data that has been stored in redis, associated with this token.
    """
    if not has_api_key_format(
            token
    ):  # The tokens are intended to have the same format as API keys.
        logging.warning("log_into_subdomain: Malformed token given: %s", token)
        return HttpResponse(status=400)

    try:
        result = ExternalAuthResult(login_token=token)
    except ExternalAuthResult.InvalidTokenError:
        logging.warning("log_into_subdomain: Invalid token given: %s", token)
        return render(request,
                      'zerver/log_into_subdomain_token_invalid.html',
                      status=400)

    subdomain = get_subdomain(request)
    if result.data_dict['subdomain'] != subdomain:
        raise JsonableError(_("Invalid subdomain"))

    return login_or_register_remote_user(request, result)
Esempio n. 4
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def finish_desktop_flow(request: HttpRequest, user_profile: UserProfile,
                        otp: str) -> HttpResponse:
    """
    The desktop otp flow returns to the app (through the clipboard)
    a token that allows obtaining (through log_into_subdomain) a logged in session
    for the user account we authenticated in this flow.
    The token can only be used once and within ExternalAuthResult.LOGIN_KEY_EXPIRATION_SECONDS
    of being created, as nothing more powerful is needed for the desktop flow
    and this ensures the key can only be used for completing this authentication attempt.
    """
    result = ExternalAuthResult(user_profile=user_profile)
    token = result.store_data()
    key = bytes.fromhex(otp)
    iv = os.urandom(12)
    desktop_data = (iv + AESGCM(key).encrypt(iv, token.encode(), b"")).hex()
    context = {
        'desktop_data':
        desktop_data,
        'browser_url':
        reverse('zerver.views.auth.login_page',
                kwargs={'template_name': 'zerver/login.html'}),
        'realm_icon_url':
        realm_icon_url(user_profile.realm)
    }
    return render(request, 'zerver/desktop_redirect.html', context=context)
Esempio n. 5
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def finish_desktop_flow(request: HttpRequest, user_profile: UserProfile,
                        otp: str) -> HttpResponse:
    """
    The desktop otp flow returns to the app (through a zulip:// redirect)
    a token that allows obtaining (through log_into_subdomain) a logged in session
    for the user account we authenticated in this flow.
    The token can only be used once and within ExternalAuthResult.LOGIN_KEY_EXPIRATION_SECONDS
    of being created, as nothing more powerful is needed for the desktop flow
    and this ensures the key can only be used for completing this authentication attempt.
    """
    result = ExternalAuthResult(user_profile=user_profile)
    token = result.store_data()
    response = create_response_for_otp_flow(
        token,
        otp,
        user_profile,
        encrypted_key_field_name='otp_encrypted_login_key')
    browser_url = user_profile.realm.uri + reverse(
        'zerver.views.auth.log_into_subdomain', args=[token])
    context = {
        'desktop_url': response['Location'],
        'browser_url': browser_url,
        'realm_icon_url': realm_icon_url(user_profile.realm)
    }
    return render(request, 'zerver/desktop_redirect.html', context=context)
Esempio n. 6
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def remote_user_sso(
        request: HttpRequest,
        mobile_flow_otp: Optional[str] = REQ(default=None),
        desktop_flow_otp: Optional[str] = REQ(default=None),
        next: str = REQ(default="/"),
) -> HttpResponse:
    subdomain = get_subdomain(request)
    try:
        realm: Optional[Realm] = get_realm(subdomain)
    except Realm.DoesNotExist:
        realm = None

    if not auth_enabled_helper([ZulipRemoteUserBackend.auth_backend_name],
                               realm):
        return config_error(request, "remote_user_backend_disabled")

    try:
        remote_user = request.META["REMOTE_USER"]
    except KeyError:
        return config_error(request, "remote_user_header_missing")

    # Django invokes authenticate methods by matching arguments, and this
    # authentication flow will not invoke LDAP authentication because of
    # this condition of Django so no need to check if LDAP backend is
    # enabled.
    validate_login_email(remote_user_to_email(remote_user))

    # Here we support the mobile and desktop flow for REMOTE_USER_BACKEND; we
    # validate the data format and then pass it through to
    # login_or_register_remote_user if appropriate.
    validate_otp_params(mobile_flow_otp, desktop_flow_otp)

    if realm is None:
        user_profile = None
    else:
        user_profile = authenticate(remote_user=remote_user, realm=realm)
    if user_profile is not None:
        assert isinstance(user_profile, UserProfile)

    email = remote_user_to_email(remote_user)
    data_dict = ExternalAuthDataDict(
        email=email,
        mobile_flow_otp=mobile_flow_otp,
        desktop_flow_otp=desktop_flow_otp,
        redirect_to=next,
    )
    if realm:
        data_dict["subdomain"] = realm.subdomain
    else:
        data_dict["subdomain"] = ""  # realm creation happens on root subdomain
    result = ExternalAuthResult(user_profile=user_profile, data_dict=data_dict)
    return login_or_register_remote_user(request, result)
Esempio n. 7
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def accounts_register(
    request: HttpRequest,
    key: str = REQ(default=""),
    timezone: str = REQ(default="", converter=to_timezone_or_empty),
    from_confirmation: Optional[str] = REQ(default=None),
    form_full_name: Optional[str] = REQ("full_name", default=None),
    source_realm_id: Optional[int] = REQ(
        default=None, converter=to_converted_or_fallback(to_non_negative_int, None)
    ),
) -> HttpResponse:
    try:
        prereg_user = check_prereg_key(request, key)
    except ConfirmationKeyException as e:
        return render_confirmation_key_error(request, e)

    email = prereg_user.email
    realm_creation = prereg_user.realm_creation
    password_required = prereg_user.password_required

    role = prereg_user.invited_as
    if realm_creation:
        role = UserProfile.ROLE_REALM_OWNER

    try:
        validators.validate_email(email)
    except ValidationError:
        return render(request, "zerver/invalid_email.html", context={"invalid_email": True})

    if realm_creation:
        # For creating a new realm, there is no existing realm or domain
        realm = None
    else:
        assert prereg_user.realm is not None
        if get_subdomain(request) != prereg_user.realm.string_id:
            return render_confirmation_key_error(
                request, ConfirmationKeyException(ConfirmationKeyException.DOES_NOT_EXIST)
            )
        realm = prereg_user.realm
        try:
            email_allowed_for_realm(email, realm)
        except DomainNotAllowedForRealmError:
            return render(
                request,
                "zerver/invalid_email.html",
                context={"realm_name": realm.name, "closed_domain": True},
            )
        except DisposableEmailError:
            return render(
                request,
                "zerver/invalid_email.html",
                context={"realm_name": realm.name, "disposable_emails_not_allowed": True},
            )
        except EmailContainsPlusError:
            return render(
                request,
                "zerver/invalid_email.html",
                context={"realm_name": realm.name, "email_contains_plus": True},
            )

        if realm.deactivated:
            # The user is trying to register for a deactivated realm. Advise them to
            # contact support.
            return redirect_to_deactivation_notice()

        try:
            validate_email_not_already_in_realm(realm, email)
        except ValidationError:
            return redirect_to_email_login_url(email)

        if settings.BILLING_ENABLED:
            try:
                check_spare_licenses_available_for_registering_new_user(realm, email)
            except LicenseLimitError:
                return render(request, "zerver/no_spare_licenses.html")

    name_validated = False
    require_ldap_password = False

    if from_confirmation:
        try:
            del request.session["authenticated_full_name"]
        except KeyError:
            pass

        ldap_full_name = None
        if settings.POPULATE_PROFILE_VIA_LDAP:
            # If the user can be found in LDAP, we'll take the full name from the directory,
            # and further down create a form pre-filled with it.
            for backend in get_backends():
                if isinstance(backend, LDAPBackend):
                    try:
                        ldap_username = backend.django_to_ldap_username(email)
                    except ZulipLDAPExceptionNoMatchingLDAPUser:
                        logging.warning("New account email %s could not be found in LDAP", email)
                        break

                    # Note that this `ldap_user` object is not a
                    # `ZulipLDAPUser` with a `Realm` attached, so
                    # calling `.populate_user()` on it will crash.
                    # This is OK, since we're just accessing this user
                    # to extract its name.
                    #
                    # TODO: We should potentially be accessing this
                    # user to sync its initial avatar and custom
                    # profile fields as well, if we indeed end up
                    # creating a user account through this flow,
                    # rather than waiting until `manage.py
                    # sync_ldap_user_data` runs to populate it.
                    ldap_user = _LDAPUser(backend, ldap_username)

                    try:
                        ldap_full_name = backend.get_mapped_name(ldap_user)
                    except TypeError:
                        break

                    # Check whether this is ZulipLDAPAuthBackend,
                    # which is responsible for authentication and
                    # requires that LDAP accounts enter their LDAP
                    # password to register, or ZulipLDAPUserPopulator,
                    # which just populates UserProfile fields (no auth).
                    require_ldap_password = isinstance(backend, ZulipLDAPAuthBackend)
                    break

        if ldap_full_name:
            # We don't use initial= here, because if the form is
            # complete (that is, no additional fields need to be
            # filled out by the user) we want the form to validate,
            # so they can be directly registered without having to
            # go through this interstitial.
            form = RegistrationForm({"full_name": ldap_full_name}, realm_creation=realm_creation)
            request.session["authenticated_full_name"] = ldap_full_name
            name_validated = True
        elif realm is not None and realm.is_zephyr_mirror_realm:
            # For MIT users, we can get an authoritative name from Hesiod.
            # Technically we should check that this is actually an MIT
            # realm, but we can cross that bridge if we ever get a non-MIT
            # zephyr mirroring realm.
            hesiod_name = compute_mit_user_fullname(email)
            form = RegistrationForm(
                initial={"full_name": hesiod_name if "@" not in hesiod_name else ""},
                realm_creation=realm_creation,
            )
            name_validated = True
        elif prereg_user.full_name:
            if prereg_user.full_name_validated:
                request.session["authenticated_full_name"] = prereg_user.full_name
                name_validated = True
                form = RegistrationForm(
                    {"full_name": prereg_user.full_name}, realm_creation=realm_creation
                )
            else:
                form = RegistrationForm(
                    initial={"full_name": prereg_user.full_name}, realm_creation=realm_creation
                )
        elif form_full_name is not None:
            form = RegistrationForm(
                initial={"full_name": form_full_name},
                realm_creation=realm_creation,
            )
        else:
            form = RegistrationForm(realm_creation=realm_creation)
    else:
        postdata = request.POST.copy()
        if name_changes_disabled(realm):
            # If we populate profile information via LDAP and we have a
            # verified name from you on file, use that. Otherwise, fall
            # back to the full name in the request.
            try:
                postdata.update(full_name=request.session["authenticated_full_name"])
                name_validated = True
            except KeyError:
                pass
        form = RegistrationForm(postdata, realm_creation=realm_creation)

    if not (password_auth_enabled(realm) and password_required):
        form["password"].field.required = False

    if form.is_valid():
        if password_auth_enabled(realm) and form["password"].field.required:
            password = form.cleaned_data["password"]
        else:
            # If the user wasn't prompted for a password when
            # completing the authentication form (because they're
            # signing up with SSO and no password is required), set
            # the password field to `None` (Which causes Django to
            # create an unusable password).
            password = None

        if realm_creation:
            string_id = form.cleaned_data["realm_subdomain"]
            realm_name = form.cleaned_data["realm_name"]
            realm_type = form.cleaned_data["realm_type"]
            is_demo_org = form.cleaned_data["is_demo_organization"]
            realm = do_create_realm(
                string_id, realm_name, org_type=realm_type, is_demo_organization=is_demo_org
            )
            setup_realm_internal_bots(realm)
        assert realm is not None

        full_name = form.cleaned_data["full_name"]
        enable_marketing_emails = form.cleaned_data["enable_marketing_emails"]
        default_stream_group_names = request.POST.getlist("default_stream_group")
        default_stream_groups = lookup_default_stream_groups(default_stream_group_names, realm)

        if source_realm_id is not None:
            # Non-integer realm_id values like "string" are treated
            # like the "Do not import" value of "".
            source_profile: Optional[UserProfile] = get_source_profile(email, source_realm_id)
        else:
            source_profile = None

        if not realm_creation:
            try:
                existing_user_profile: Optional[UserProfile] = get_user_by_delivery_email(
                    email, realm
                )
            except UserProfile.DoesNotExist:
                existing_user_profile = None
        else:
            existing_user_profile = None

        user_profile: Optional[UserProfile] = None
        return_data: Dict[str, bool] = {}
        if ldap_auth_enabled(realm):
            # If the user was authenticated using an external SSO
            # mechanism like Google or GitHub auth, then authentication
            # will have already been done before creating the
            # PreregistrationUser object with password_required=False, and
            # so we don't need to worry about passwords.
            #
            # If instead the realm is using EmailAuthBackend, we will
            # set their password above.
            #
            # But if the realm is using LDAPAuthBackend, we need to verify
            # their LDAP password (which will, as a side effect, create
            # the user account) here using authenticate.
            # pregeg_user.realm_creation carries the information about whether
            # we're in realm creation mode, and the ldap flow will handle
            # that and create the user with the appropriate parameters.
            user_profile = authenticate(
                request=request,
                username=email,
                password=password,
                realm=realm,
                prereg_user=prereg_user,
                return_data=return_data,
            )
            if user_profile is None:
                can_use_different_backend = email_auth_enabled(realm) or (
                    len(get_external_method_dicts(realm)) > 0
                )
                if settings.LDAP_APPEND_DOMAIN:
                    # In LDAP_APPEND_DOMAIN configurations, we don't allow making a non-LDAP account
                    # if the email matches the ldap domain.
                    can_use_different_backend = can_use_different_backend and (
                        not email_belongs_to_ldap(realm, email)
                    )
                if return_data.get("no_matching_ldap_user") and can_use_different_backend:
                    # If both the LDAP and Email or Social auth backends are
                    # enabled, and there's no matching user in the LDAP
                    # directory then the intent is to create a user in the
                    # realm with their email outside the LDAP organization
                    # (with e.g. a password stored in the Zulip database,
                    # not LDAP).  So we fall through and create the new
                    # account.
                    pass
                else:
                    # TODO: This probably isn't going to give a
                    # user-friendly error message, but it doesn't
                    # particularly matter, because the registration form
                    # is hidden for most users.
                    view_url = reverse("login")
                    query = urlencode({"email": email})
                    redirect_url = append_url_query_string(view_url, query)
                    return HttpResponseRedirect(redirect_url)
            elif not realm_creation:
                # Since we'll have created a user, we now just log them in.
                return login_and_go_to_home(request, user_profile)
            else:
                # With realm_creation=True, we're going to return further down,
                # after finishing up the creation process.
                pass

        if existing_user_profile is not None and existing_user_profile.is_mirror_dummy:
            user_profile = existing_user_profile
            do_activate_mirror_dummy_user(user_profile, acting_user=user_profile)
            do_change_password(user_profile, password)
            do_change_full_name(user_profile, full_name, user_profile)
            do_change_user_setting(user_profile, "timezone", timezone, acting_user=user_profile)
            # TODO: When we clean up the `do_activate_mirror_dummy_user` code path,
            # make it respect invited_as_admin / is_realm_admin.

        if user_profile is None:
            user_profile = do_create_user(
                email,
                password,
                realm,
                full_name,
                prereg_user=prereg_user,
                role=role,
                tos_version=settings.TOS_VERSION,
                timezone=timezone,
                default_stream_groups=default_stream_groups,
                source_profile=source_profile,
                realm_creation=realm_creation,
                acting_user=None,
                enable_marketing_emails=enable_marketing_emails,
            )

        if realm_creation:
            assert realm.signup_notifications_stream is not None
            bulk_add_subscriptions(
                realm, [realm.signup_notifications_stream], [user_profile], acting_user=None
            )
            send_initial_realm_messages(realm)

            # Because for realm creation, registration happens on the
            # root domain, we need to log them into the subdomain for
            # their new realm.
            return redirect_and_log_into_subdomain(
                ExternalAuthResult(user_profile=user_profile, data_dict={"is_realm_creation": True})
            )

        # This dummy_backend check below confirms the user is
        # authenticating to the correct subdomain.
        auth_result = authenticate(
            username=user_profile.delivery_email,
            realm=realm,
            return_data=return_data,
            use_dummy_backend=True,
        )
        if return_data.get("invalid_subdomain"):
            # By construction, this should never happen.
            logging.error(
                "Subdomain mismatch in registration %s: %s",
                realm.subdomain,
                user_profile.delivery_email,
            )
            return redirect("/")

        return login_and_go_to_home(request, auth_result)

    return render(
        request,
        "zerver/register.html",
        context={
            "form": form,
            "email": email,
            "key": key,
            "full_name": request.session.get("authenticated_full_name", None),
            "lock_name": name_validated and name_changes_disabled(realm),
            # password_auth_enabled is normally set via our context processor,
            # but for the registration form, there is no logged in user yet, so
            # we have to set it here.
            "creating_new_team": realm_creation,
            "password_required": password_auth_enabled(realm) and password_required,
            "require_ldap_password": require_ldap_password,
            "password_auth_enabled": password_auth_enabled(realm),
            "root_domain_available": is_root_domain_available(),
            "default_stream_groups": [] if realm is None else get_default_stream_groups(realm),
            "accounts": get_accounts_for_email(email),
            "MAX_REALM_NAME_LENGTH": str(Realm.MAX_REALM_NAME_LENGTH),
            "MAX_NAME_LENGTH": str(UserProfile.MAX_NAME_LENGTH),
            "MAX_PASSWORD_LENGTH": str(form.MAX_PASSWORD_LENGTH),
            "MAX_REALM_SUBDOMAIN_LENGTH": str(Realm.MAX_REALM_SUBDOMAIN_LENGTH),
            "sorted_realm_types": sorted(
                Realm.ORG_TYPES.values(), key=lambda d: d["display_order"]
            ),
        },
    )
Esempio n. 8
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def accounts_register(request: HttpRequest) -> HttpResponse:
    try:
        key = request.POST.get('key', default='')
        confirmation = Confirmation.objects.get(confirmation_key=key)
    except Confirmation.DoesNotExist:
        return render(request, "zerver/confirmation_link_expired_error.html")

    prereg_user = confirmation.content_object
    if prereg_user.status == confirmation_settings.STATUS_REVOKED:
        return render(request, "zerver/confirmation_link_expired_error.html")
    email = prereg_user.email
    realm_creation = prereg_user.realm_creation
    password_required = prereg_user.password_required

    role = get_role_for_new_user(prereg_user.invited_as, realm_creation)

    try:
        validators.validate_email(email)
    except ValidationError:
        return render(request,
                      "zerver/invalid_email.html",
                      context={"invalid_email": True})

    if realm_creation:
        # For creating a new realm, there is no existing realm or domain
        realm = None
    else:
        if get_subdomain(request) != prereg_user.realm.string_id:
            return render_confirmation_key_error(
                request,
                ConfirmationKeyException(
                    ConfirmationKeyException.DOES_NOT_EXIST))
        realm = prereg_user.realm
        try:
            email_allowed_for_realm(email, realm)
        except DomainNotAllowedForRealmError:
            return render(request,
                          "zerver/invalid_email.html",
                          context={
                              "realm_name": realm.name,
                              "closed_domain": True
                          })
        except DisposableEmailError:
            return render(request,
                          "zerver/invalid_email.html",
                          context={
                              "realm_name": realm.name,
                              "disposable_emails_not_allowed": True
                          })
        except EmailContainsPlusError:
            return render(request,
                          "zerver/invalid_email.html",
                          context={
                              "realm_name": realm.name,
                              "email_contains_plus": True
                          })

        if realm.deactivated:
            # The user is trying to register for a deactivated realm. Advise them to
            # contact support.
            return redirect_to_deactivation_notice()

        try:
            validate_email_not_already_in_realm(realm, email)
        except ValidationError:
            view_url = reverse('login')
            redirect_url = add_query_to_redirect_url(
                view_url, 'email=' + urllib.parse.quote_plus(email))
            return HttpResponseRedirect(redirect_url)

    name_validated = False
    full_name = None
    require_ldap_password = False

    if request.POST.get('from_confirmation'):
        try:
            del request.session['authenticated_full_name']
        except KeyError:
            pass

        ldap_full_name = None
        if settings.POPULATE_PROFILE_VIA_LDAP:
            # If the user can be found in LDAP, we'll take the full name from the directory,
            # and further down create a form pre-filled with it.
            for backend in get_backends():
                if isinstance(backend, LDAPBackend):
                    try:
                        ldap_username = backend.django_to_ldap_username(email)
                    except ZulipLDAPExceptionNoMatchingLDAPUser:
                        logging.warning(
                            "New account email %s could not be found in LDAP",
                            email)
                        break

                    # Note that this `ldap_user` object is not a
                    # `ZulipLDAPUser` with a `Realm` attached, so
                    # calling `.populate_user()` on it will crash.
                    # This is OK, since we're just accessing this user
                    # to extract its name.
                    #
                    # TODO: We should potentially be accessing this
                    # user to sync its initial avatar and custom
                    # profile fields as well, if we indeed end up
                    # creating a user account through this flow,
                    # rather than waiting until `manage.py
                    # sync_ldap_user_data` runs to populate it.
                    ldap_user = _LDAPUser(backend, ldap_username)

                    try:
                        ldap_full_name = backend.get_mapped_name(ldap_user)
                    except TypeError:
                        break

                    # Check whether this is ZulipLDAPAuthBackend,
                    # which is responsible for authentication and
                    # requires that LDAP accounts enter their LDAP
                    # password to register, or ZulipLDAPUserPopulator,
                    # which just populates UserProfile fields (no auth).
                    require_ldap_password = isinstance(backend,
                                                       ZulipLDAPAuthBackend)
                    break

        if ldap_full_name:
            # We don't use initial= here, because if the form is
            # complete (that is, no additional fields need to be
            # filled out by the user) we want the form to validate,
            # so they can be directly registered without having to
            # go through this interstitial.
            form = RegistrationForm({'full_name': ldap_full_name},
                                    realm_creation=realm_creation)
            request.session['authenticated_full_name'] = ldap_full_name
            name_validated = True
        elif realm is not None and realm.is_zephyr_mirror_realm:
            # For MIT users, we can get an authoritative name from Hesiod.
            # Technically we should check that this is actually an MIT
            # realm, but we can cross that bridge if we ever get a non-MIT
            # zephyr mirroring realm.
            hesiod_name = compute_mit_user_fullname(email)
            form = RegistrationForm(initial={
                'full_name':
                hesiod_name if "@" not in hesiod_name else ""
            },
                                    realm_creation=realm_creation)
            name_validated = True
        elif prereg_user.full_name:
            if prereg_user.full_name_validated:
                request.session[
                    'authenticated_full_name'] = prereg_user.full_name
                name_validated = True
                form = RegistrationForm({'full_name': prereg_user.full_name},
                                        realm_creation=realm_creation)
            else:
                form = RegistrationForm(
                    initial={'full_name': prereg_user.full_name},
                    realm_creation=realm_creation)
        elif 'full_name' in request.POST:
            form = RegistrationForm(
                initial={'full_name': request.POST.get('full_name')},
                realm_creation=realm_creation,
            )
        else:
            form = RegistrationForm(realm_creation=realm_creation)
    else:
        postdata = request.POST.copy()
        if name_changes_disabled(realm):
            # If we populate profile information via LDAP and we have a
            # verified name from you on file, use that. Otherwise, fall
            # back to the full name in the request.
            try:
                postdata.update(
                    full_name=request.session['authenticated_full_name'])
                name_validated = True
            except KeyError:
                pass
        form = RegistrationForm(postdata, realm_creation=realm_creation)

    if not (password_auth_enabled(realm) and password_required):
        form['password'].field.required = False

    if form.is_valid():
        if password_auth_enabled(realm) and form['password'].field.required:
            password = form.cleaned_data['password']
        else:
            # If the user wasn't prompted for a password when
            # completing the authentication form (because they're
            # signing up with SSO and no password is required), set
            # the password field to `None` (Which causes Django to
            # create an unusable password).
            password = None

        if realm_creation:
            string_id = form.cleaned_data['realm_subdomain']
            realm_name = form.cleaned_data['realm_name']
            realm = do_create_realm(string_id, realm_name)
            setup_realm_internal_bots(realm)
        assert (realm is not None)

        full_name = form.cleaned_data['full_name']
        default_stream_group_names = request.POST.getlist(
            'default_stream_group')
        default_stream_groups = lookup_default_stream_groups(
            default_stream_group_names, realm)

        timezone = ""
        if 'timezone' in request.POST and request.POST[
                'timezone'] in get_all_timezones():
            timezone = request.POST['timezone']

        if 'source_realm' in request.POST and request.POST[
                "source_realm"] != "on":
            source_profile = get_source_profile(email,
                                                request.POST["source_realm"])
        else:
            source_profile = None

        if not realm_creation:
            try:
                existing_user_profile: Optional[
                    UserProfile] = get_user_by_delivery_email(email, realm)
            except UserProfile.DoesNotExist:
                existing_user_profile = None
        else:
            existing_user_profile = None

        user_profile: Optional[UserProfile] = None
        return_data: Dict[str, bool] = {}
        if ldap_auth_enabled(realm):
            # If the user was authenticated using an external SSO
            # mechanism like Google or GitHub auth, then authentication
            # will have already been done before creating the
            # PreregistrationUser object with password_required=False, and
            # so we don't need to worry about passwords.
            #
            # If instead the realm is using EmailAuthBackend, we will
            # set their password above.
            #
            # But if the realm is using LDAPAuthBackend, we need to verify
            # their LDAP password (which will, as a side effect, create
            # the user account) here using authenticate.
            # pregeg_user.realm_creation carries the information about whether
            # we're in realm creation mode, and the ldap flow will handle
            # that and create the user with the appropriate parameters.
            user_profile = authenticate(request=request,
                                        username=email,
                                        password=password,
                                        realm=realm,
                                        prereg_user=prereg_user,
                                        return_data=return_data)
            if user_profile is None:
                can_use_different_backend = email_auth_enabled(
                    realm) or any_social_backend_enabled(realm)
                if settings.LDAP_APPEND_DOMAIN:
                    # In LDAP_APPEND_DOMAIN configurations, we don't allow making a non-ldap account
                    # if the email matches the ldap domain.
                    can_use_different_backend = can_use_different_backend and (
                        not email_belongs_to_ldap(realm, email))
                if return_data.get(
                        "no_matching_ldap_user") and can_use_different_backend:
                    # If both the LDAP and Email or Social auth backends are
                    # enabled, and there's no matching user in the LDAP
                    # directory then the intent is to create a user in the
                    # realm with their email outside the LDAP organization
                    # (with e.g. a password stored in the Zulip database,
                    # not LDAP).  So we fall through and create the new
                    # account.
                    pass
                else:
                    # TODO: This probably isn't going to give a
                    # user-friendly error message, but it doesn't
                    # particularly matter, because the registration form
                    # is hidden for most users.
                    view_url = reverse('login')
                    query = 'email=' + urllib.parse.quote_plus(email)
                    redirect_url = add_query_to_redirect_url(view_url, query)
                    return HttpResponseRedirect(redirect_url)
            elif not realm_creation:
                # Since we'll have created a user, we now just log them in.
                return login_and_go_to_home(request, user_profile)
            else:
                # With realm_creation=True, we're going to return further down,
                # after finishing up the creation process.
                pass

        if existing_user_profile is not None and existing_user_profile.is_mirror_dummy:
            user_profile = existing_user_profile
            do_activate_user(user_profile, acting_user=user_profile)
            do_change_password(user_profile, password)
            do_change_full_name(user_profile, full_name, user_profile)
            do_set_user_display_setting(user_profile, 'timezone', timezone)
            # TODO: When we clean up the `do_activate_user` code path,
            # make it respect invited_as_admin / is_realm_admin.

        if user_profile is None:
            user_profile = do_create_user(
                email,
                password,
                realm,
                full_name,
                prereg_user=prereg_user,
                role=role,
                tos_version=settings.TOS_VERSION,
                timezone=timezone,
                newsletter_data={"IP": request.META['REMOTE_ADDR']},
                default_stream_groups=default_stream_groups,
                source_profile=source_profile,
                realm_creation=realm_creation,
                acting_user=None)

        if realm_creation:
            bulk_add_subscriptions([realm.signup_notifications_stream],
                                   [user_profile])
            send_initial_realm_messages(realm)

            # Because for realm creation, registration happens on the
            # root domain, we need to log them into the subdomain for
            # their new realm.
            return redirect_and_log_into_subdomain(
                ExternalAuthResult(user_profile=user_profile,
                                   data_dict={'is_realm_creation': True}))

        # This dummy_backend check below confirms the user is
        # authenticating to the correct subdomain.
        auth_result = authenticate(username=user_profile.delivery_email,
                                   realm=realm,
                                   return_data=return_data,
                                   use_dummy_backend=True)
        if return_data.get('invalid_subdomain'):
            # By construction, this should never happen.
            logging.error(
                "Subdomain mismatch in registration %s: %s",
                realm.subdomain,
                user_profile.delivery_email,
            )
            return redirect('/')

        return login_and_go_to_home(request, auth_result)

    return render(
        request,
        'zerver/register.html',
        context={
            'form':
            form,
            'email':
            email,
            'key':
            key,
            'full_name':
            request.session.get('authenticated_full_name', None),
            'lock_name':
            name_validated and name_changes_disabled(realm),
            # password_auth_enabled is normally set via our context processor,
            # but for the registration form, there is no logged in user yet, so
            # we have to set it here.
            'creating_new_team':
            realm_creation,
            'password_required':
            password_auth_enabled(realm) and password_required,
            'require_ldap_password':
            require_ldap_password,
            'password_auth_enabled':
            password_auth_enabled(realm),
            'root_domain_available':
            is_root_domain_available(),
            'default_stream_groups':
            [] if realm is None else get_default_stream_groups(realm),
            'accounts':
            get_accounts_for_email(email),
            'MAX_REALM_NAME_LENGTH':
            str(Realm.MAX_REALM_NAME_LENGTH),
            'MAX_NAME_LENGTH':
            str(UserProfile.MAX_NAME_LENGTH),
            'MAX_PASSWORD_LENGTH':
            str(form.MAX_PASSWORD_LENGTH),
            'MAX_REALM_SUBDOMAIN_LENGTH':
            str(Realm.MAX_REALM_SUBDOMAIN_LENGTH),
        },
    )