224 lines
8.0 KiB
Python
224 lines
8.0 KiB
Python
# Copyright 2021 The Matrix.org C.I.C. Foundation
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import email.utils
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import logging
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from email.mime.multipart import MIMEMultipart
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from email.mime.text import MIMEText
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from io import BytesIO
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from typing import TYPE_CHECKING, Any, Dict, Optional
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from pkg_resources import parse_version
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import twisted
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from twisted.internet.defer import Deferred
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from twisted.internet.endpoints import HostnameEndpoint
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from twisted.internet.interfaces import IOpenSSLContextFactory, IProtocolFactory
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from twisted.internet.ssl import optionsForClientTLS
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from twisted.mail.smtp import ESMTPSender, ESMTPSenderFactory
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from twisted.protocols.tls import TLSMemoryBIOFactory
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from synapse.logging.context import make_deferred_yieldable
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from synapse.types import ISynapseReactor
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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_is_old_twisted = parse_version(twisted.__version__) < parse_version("21")
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class _NoTLSESMTPSender(ESMTPSender):
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"""Extend ESMTPSender to disable TLS
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Unfortunately, before Twisted 21.2, ESMTPSender doesn't give an easy way to disable
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TLS, so we override its internal method which it uses to generate a context factory.
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"""
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def _getContextFactory(self) -> Optional[IOpenSSLContextFactory]:
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return None
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async def _sendmail(
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reactor: ISynapseReactor,
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smtphost: str,
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smtpport: int,
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from_addr: str,
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to_addr: str,
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msg_bytes: bytes,
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username: Optional[bytes] = None,
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password: Optional[bytes] = None,
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require_auth: bool = False,
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require_tls: bool = False,
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enable_tls: bool = True,
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force_tls: bool = False,
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) -> None:
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"""A simple wrapper around ESMTPSenderFactory, to allow substitution in tests
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Params:
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reactor: reactor to use to make the outbound connection
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smtphost: hostname to connect to
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smtpport: port to connect to
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from_addr: "From" address for email
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to_addr: "To" address for email
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msg_bytes: Message content
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username: username to authenticate with, if auth is enabled
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password: password to give when authenticating
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require_auth: if auth is not offered, fail the request
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require_tls: if TLS is not offered, fail the reqest
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enable_tls: True to enable STARTTLS. If this is False and require_tls is True,
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the request will fail.
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force_tls: True to enable Implicit TLS.
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"""
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msg = BytesIO(msg_bytes)
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d: "Deferred[object]" = Deferred()
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def build_sender_factory(**kwargs: Any) -> ESMTPSenderFactory:
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return ESMTPSenderFactory(
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username,
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password,
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from_addr,
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to_addr,
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msg,
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d,
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heloFallback=True,
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requireAuthentication=require_auth,
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requireTransportSecurity=require_tls,
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**kwargs,
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)
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factory: IProtocolFactory
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if _is_old_twisted:
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# before twisted 21.2, we have to override the ESMTPSender protocol to disable
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# TLS
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factory = build_sender_factory()
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if not enable_tls:
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factory.protocol = _NoTLSESMTPSender
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else:
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# for twisted 21.2 and later, there is a 'hostname' parameter which we should
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# set to enable TLS.
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factory = build_sender_factory(hostname=smtphost if enable_tls else None)
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if force_tls:
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factory = TLSMemoryBIOFactory(optionsForClientTLS(smtphost), True, factory)
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endpoint = HostnameEndpoint(
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reactor, smtphost, smtpport, timeout=30, bindAddress=None
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)
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await make_deferred_yieldable(endpoint.connect(factory))
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await make_deferred_yieldable(d)
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class SendEmailHandler:
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def __init__(self, hs: "HomeServer"):
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self.hs = hs
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self._reactor = hs.get_reactor()
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self._from = hs.config.email.email_notif_from
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self._smtp_host = hs.config.email.email_smtp_host
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self._smtp_port = hs.config.email.email_smtp_port
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user = hs.config.email.email_smtp_user
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self._smtp_user = user.encode("utf-8") if user is not None else None
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passwd = hs.config.email.email_smtp_pass
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self._smtp_pass = passwd.encode("utf-8") if passwd is not None else None
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self._require_transport_security = hs.config.email.require_transport_security
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self._enable_tls = hs.config.email.enable_smtp_tls
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self._force_tls = hs.config.email.force_tls
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self._sendmail = _sendmail
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async def send_email(
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self,
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email_address: str,
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subject: str,
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app_name: str,
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html: str,
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text: str,
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additional_headers: Optional[Dict[str, str]] = None,
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) -> None:
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"""Send a multipart email with the given information.
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Args:
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email_address: The address to send the email to.
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subject: The email's subject.
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app_name: The app name to include in the From header.
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html: The HTML content to include in the email.
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text: The plain text content to include in the email.
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additional_headers: A map of additional headers to include.
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"""
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try:
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from_string = self._from % {"app": app_name}
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except (KeyError, TypeError):
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from_string = self._from
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raw_from = email.utils.parseaddr(from_string)[1]
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raw_to = email.utils.parseaddr(email_address)[1]
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if raw_to == "":
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raise RuntimeError("Invalid 'to' address")
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html_part = MIMEText(html, "html", "utf-8")
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text_part = MIMEText(text, "plain", "utf-8")
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multipart_msg = MIMEMultipart("alternative")
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multipart_msg["Subject"] = subject
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multipart_msg["From"] = from_string
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multipart_msg["To"] = email_address
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multipart_msg["Date"] = email.utils.formatdate()
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multipart_msg["Message-ID"] = email.utils.make_msgid()
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# Discourage automatic responses to Synapse's emails.
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# Per RFC 3834, automatic responses should not be sent if the "Auto-Submitted"
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# header is present with any value other than "no". See
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# https://www.rfc-editor.org/rfc/rfc3834.html#section-5.1
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multipart_msg["Auto-Submitted"] = "auto-generated"
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# Also include a Microsoft-Exchange specific header:
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# https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxcmail/ced68690-498a-4567-9d14-5c01f974d8b1
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# which suggests it can take the value "All" to "suppress all auto-replies",
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# or a comma separated list of auto-reply classes to suppress.
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# The following stack overflow question has a little more context:
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# https://stackoverflow.com/a/25324691/5252017
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# https://stackoverflow.com/a/61646381/5252017
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multipart_msg["X-Auto-Response-Suppress"] = "All"
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if additional_headers:
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for header, value in additional_headers.items():
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multipart_msg[header] = value
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multipart_msg.attach(text_part)
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multipart_msg.attach(html_part)
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logger.info("Sending email to %s" % email_address)
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await self._sendmail(
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self._reactor,
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self._smtp_host,
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self._smtp_port,
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raw_from,
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raw_to,
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multipart_msg.as_string().encode("utf8"),
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username=self._smtp_user,
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password=self._smtp_pass,
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require_auth=self._smtp_user is not None,
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require_tls=self._require_transport_security,
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enable_tls=self._enable_tls,
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force_tls=self._force_tls,
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)
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