Send out emails with links to extend an account's validity period

1 files changed, 228 insertions, 0 deletions

diff --git a/synapse/handlers/account_validity.py b/synapse/handlers/account_validity.py
new file mode 100644
index 0000000000..e82049e42d
--- /dev/null
+++ b/synapse/handlers/account_validity.py
@@ -0,0 +1,228 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector 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 email.mime.multipart
+import email.utils
+import logging
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+
+from twisted.internet import defer
+
+from synapse.api.errors import StoreError
+from synapse.types import UserID
+from synapse.util import stringutils
+from synapse.util.logcontext import make_deferred_yieldable
+
+try:
+    from synapse.push.mailer import load_jinja2_templates
+except ImportError:
+    load_jinja2_templates = None
+
+logger = logging.getLogger(__name__)
+
+
+class AccountValidityHandler(object):
+    def __init__(self, hs):
+        self.hs = hs
+        self.store = self.hs.get_datastore()
+        self.sendmail = self.hs.get_sendmail()
+        self.clock = self.hs.get_clock()
+
+        self._account_validity = self.hs.config.account_validity
+
+        if self._account_validity.renew_by_email_enabled and load_jinja2_templates:
+            # Don't do email-specific configuration if renewal by email is disabled.
+            try:
+                app_name = self.hs.config.email_app_name
+
+                self._subject = self._account_validity.renew_email_subject % {
+                    "app": app_name,
+                }
+
+                self._from_string = self.hs.config.email_notif_from % {
+                    "app": app_name,
+                }
+            except Exception:
+                # If substitution failed, fall back to the bare strings.
+                self._subject = self._account_validity.renew_email_subject
+                self._from_string = self.hs.config.email_notif_from
+
+            self._raw_from = email.utils.parseaddr(self._from_string)[1]
+
+            self._template_html, self._template_text = load_jinja2_templates(
+                config=self.hs.config,
+                template_html_name=self.hs.config.email_expiry_template_html,
+                template_text_name=self.hs.config.email_expiry_template_text,
+            )
+
+            # Check the renewal emails to send and send them every 30min.
+            self.clock.looping_call(
+                self.send_renewal_emails,
+                30 * 60 * 1000,
+            )
+
+    @defer.inlineCallbacks
+    def send_renewal_emails(self):
+        """Gets the list of users whose account is expiring in the amount of time
+        configured in the ``renew_at`` parameter from the ``account_validity``
+        configuration, and sends renewal emails to all of these users as long as they
+        have an email 3PID attached to their account.
+        """
+        expiring_users = yield self.store.get_users_expiring_soon()
+
+        if expiring_users:
+            for user in expiring_users:
+                yield self._send_renewal_email(
+                    user_id=user["user_id"],
+                    expiration_ts=user["expiration_ts_ms"],
+                )
+
+    @defer.inlineCallbacks
+    def _send_renewal_email(self, user_id, expiration_ts):
+        """Sends out a renewal email to every email address attached to the given user
+        with a unique link allowing them to renew their account.
+
+        Args:
+            user_id (str): ID of the user to send email(s) to.
+            expiration_ts (int): Timestamp in milliseconds for the expiration date of
+                this user's account (used in the email templates).
+        """
+        addresses = yield self._get_email_addresses_for_user(user_id)
+
+        # Stop right here if the user doesn't have at least one email address.
+        # In this case, they will have to ask their server admin to renew their
+        # account manually.
+        if not addresses:
+            return
+
+        try:
+            user_display_name = yield self.store.get_profile_displayname(
+                UserID.from_string(user_id).localpart
+            )
+            if user_display_name is None:
+                user_display_name = user_id
+        except StoreError:
+            user_display_name = user_id
+
+        renewal_token = yield self._get_renewal_token(user_id)
+        url = "%s_matrix/client/unstable/account_validity/renew?token=%s" % (
+            self.hs.config.public_baseurl,
+            renewal_token,
+        )
+
+        template_vars = {
+            "display_name": user_display_name,
+            "expiration_ts": expiration_ts,
+            "url": url,
+        }
+
+        html_text = self._template_html.render(**template_vars)
+        html_part = MIMEText(html_text, "html", "utf8")
+
+        plain_text = self._template_text.render(**template_vars)
+        text_part = MIMEText(plain_text, "plain", "utf8")
+
+        for address in addresses:
+            raw_to = email.utils.parseaddr(address)[1]
+
+            multipart_msg = MIMEMultipart('alternative')
+            multipart_msg['Subject'] = self._subject
+            multipart_msg['From'] = self._from_string
+            multipart_msg['To'] = address
+            multipart_msg['Date'] = email.utils.formatdate()
+            multipart_msg['Message-ID'] = email.utils.make_msgid()
+            multipart_msg.attach(text_part)
+            multipart_msg.attach(html_part)
+
+            logger.info("Sending renewal email to %s", address)
+
+            yield make_deferred_yieldable(self.sendmail(
+                self.hs.config.email_smtp_host,
+                self._raw_from, raw_to, multipart_msg.as_string().encode('utf8'),
+                reactor=self.hs.get_reactor(),
+                port=self.hs.config.email_smtp_port,
+                requireAuthentication=self.hs.config.email_smtp_user is not None,
+                username=self.hs.config.email_smtp_user,
+                password=self.hs.config.email_smtp_pass,
+                requireTransportSecurity=self.hs.config.require_transport_security
+            ))
+
+        yield self.store.set_renewal_mail_status(
+            user_id=user_id,
+            email_sent=True,
+        )
+
+    @defer.inlineCallbacks
+    def _get_email_addresses_for_user(self, user_id):
+        """Retrieve the list of email addresses attached to a user's account.
+
+        Args:
+            user_id (str): ID of the user to lookup email addresses for.
+
+        Returns:
+            defer.Deferred[list[str]]: Email addresses for this account.
+        """
+        threepids = yield self.store.user_get_threepids(user_id)
+
+        addresses = []
+        for threepid in threepids:
+            if threepid["medium"] == "email":
+                addresses.append(threepid["address"])
+
+        defer.returnValue(addresses)
+
+    @defer.inlineCallbacks
+    def _get_renewal_token(self, user_id):
+        """Generates a 32-byte long random string that will be inserted into the
+        user's renewal email's unique link, then saves it into the database.
+
+        Args:
+            user_id (str): ID of the user to generate a string for.
+
+        Returns:
+            defer.Deferred[str]: The generated string.
+
+        Raises:
+            StoreError(500): Couldn't generate a unique string after 5 attempts.
+        """
+        attempts = 0
+        while attempts < 5:
+            try:
+                renewal_token = stringutils.random_string(32)
+                yield self.store.set_renewal_token_for_user(user_id, renewal_token)
+                defer.returnValue(renewal_token)
+            except StoreError:
+                attempts += 1
+        raise StoreError(500, "Couldn't generate a unique string as refresh string.")
+
+    @defer.inlineCallbacks
+    def renew_account(self, renewal_token):
+        """Renews the account attached to a given renewal token by pushing back the
+        expiration date by the current validity period in the server's configuration.
+
+        Args:
+            renewal_token (str): Token sent with the renewal request.
+        """
+        user_id = yield self.store.get_user_from_renewal_token(renewal_token)
+
+        logger.debug("Renewing an account for user %s", user_id)
+
+        new_expiration_date = self.clock.time_msec() + self._account_validity.period
+
+        yield self.store.renew_account_for_user(
+            user_id=user_id,
+            new_expiration_ts=new_expiration_date,
+        )