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app-MAIL-temp/app/email_utils.py

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Python
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import base64
import binascii
import enum
import hmac
import json
import os
import quopri
import random
import time
import uuid
from copy import deepcopy
from email import policy, message_from_bytes, message_from_string
from email.header import decode_header, Header
from email.message import Message, EmailMessage
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import make_msgid, formatdate, formataddr
from smtplib import SMTP, SMTPException
from typing import Tuple, List, Optional, Union
import arrow
import dkim
import re2 as re
import spf
from aiosmtpd.smtp import Envelope
from cachetools import cached, TTLCache
from email_validator import (
validate_email,
EmailNotValidError,
ValidatedEmail,
)
from flanker.addresslib import address
from flanker.addresslib.address import EmailAddress
from jinja2 import Environment, FileSystemLoader
from sqlalchemy import func
from app import config
from app.db import Session
from app.dns_utils import get_mx_domains
from app.email import headers
from app.log import LOG
from app.mail_sender import sl_sendmail
from app.message_utils import message_to_bytes
from app.models import (
Mailbox,
User,
SentAlert,
CustomDomain,
SLDomain,
Contact,
Alias,
EmailLog,
TransactionalEmail,
IgnoreBounceSender,
InvalidMailboxDomain,
VerpType,
)
from app.utils import (
random_string,
convert_to_id,
convert_to_alphanumeric,
sanitize_email,
)
# 2022-01-01 00:00:00
VERP_TIME_START = 1640995200
VERP_HMAC_ALGO = "sha3-224"
def render(template_name, **kwargs) -> str:
templates_dir = os.path.join(config.ROOT_DIR, "templates", "emails")
env = Environment(loader=FileSystemLoader(templates_dir))
template = env.get_template(template_name)
return template.render(
MAX_NB_EMAIL_FREE_PLAN=config.MAX_NB_EMAIL_FREE_PLAN,
URL=config.URL,
LANDING_PAGE_URL=config.LANDING_PAGE_URL,
YEAR=arrow.now().year,
**kwargs,
)
def send_welcome_email(user):
comm_email, unsubscribe_link, via_email = user.get_communication_email()
if not comm_email:
return
# whether this email is sent to an alias
alias = comm_email if comm_email != user.email else None
send_email(
comm_email,
f"Welcome to SimpleLogin",
render("com/welcome.txt", user=user, alias=alias),
render("com/welcome.html", user=user, alias=alias),
unsubscribe_link,
via_email,
)
def send_trial_end_soon_email(user):
send_email(
user.email,
f"Your trial will end soon",
render("transactional/trial-end.txt.jinja2", user=user),
render("transactional/trial-end.html", user=user),
ignore_smtp_error=True,
)
def send_activation_email(email, activation_link):
send_email(
email,
f"Just one more step to join SimpleLogin",
render(
"transactional/activation.txt",
activation_link=activation_link,
email=email,
),
render(
"transactional/activation.html",
activation_link=activation_link,
email=email,
),
)
def send_reset_password_email(email, reset_password_link):
send_email(
email,
"Reset your password on SimpleLogin",
render(
"transactional/reset-password.txt",
reset_password_link=reset_password_link,
),
render(
"transactional/reset-password.html",
reset_password_link=reset_password_link,
),
)
def send_change_email(new_email, current_email, link):
send_email(
new_email,
"Confirm email update on SimpleLogin",
render(
"transactional/change-email.txt",
link=link,
new_email=new_email,
current_email=current_email,
),
render(
"transactional/change-email.html",
link=link,
new_email=new_email,
current_email=current_email,
),
)
def send_invalid_totp_login_email(user, totp_type):
send_email_with_rate_control(
user,
config.ALERT_INVALID_TOTP_LOGIN,
user.email,
"Unsuccessful attempt to login to your SimpleLogin account",
render(
"transactional/invalid-totp-login.txt",
type=totp_type,
),
render(
"transactional/invalid-totp-login.html",
type=totp_type,
),
1,
)
def send_test_email_alias(email, name):
send_email(
email,
f"This email is sent to {email}",
render(
"transactional/test-email.txt",
name=name,
alias=email,
),
render(
"transactional/test-email.html",
name=name,
alias=email,
),
)
def send_cannot_create_directory_alias(user, alias_address, directory_name):
"""when user cancels their subscription, they cannot create alias on the fly.
If this happens, send them an email to notify
"""
send_email(
user.email,
f"Alias {alias_address} cannot be created",
render(
"transactional/cannot-create-alias-directory.txt",
alias=alias_address,
directory=directory_name,
),
render(
"transactional/cannot-create-alias-directory.html",
alias=alias_address,
directory=directory_name,
),
)
def send_cannot_create_directory_alias_disabled(user, alias_address, directory_name):
"""when the directory is disabled, new alias can't be created on-the-fly.
Send user an email to notify of an attempt
"""
send_email_with_rate_control(
user,
config.ALERT_DIRECTORY_DISABLED_ALIAS_CREATION,
user.email,
f"Alias {alias_address} cannot be created",
render(
"transactional/cannot-create-alias-directory-disabled.txt",
alias=alias_address,
directory=directory_name,
),
render(
"transactional/cannot-create-alias-directory-disabled.html",
alias=alias_address,
directory=directory_name,
),
)
def send_cannot_create_domain_alias(user, alias, domain):
"""when user cancels their subscription, they cannot create alias on the fly with custom domain.
If this happens, send them an email to notify
"""
send_email(
user.email,
f"Alias {alias} cannot be created",
render(
"transactional/cannot-create-alias-domain.txt",
alias=alias,
domain=domain,
),
render(
"transactional/cannot-create-alias-domain.html",
alias=alias,
domain=domain,
),
)
def send_email(
to_email,
subject,
plaintext,
html=None,
unsubscribe_link=None,
unsubscribe_via_email=False,
retries=0, # by default no retry if sending fails
ignore_smtp_error=False,
from_name=None,
from_addr=None,
):
to_email = sanitize_email(to_email)
LOG.d("send email to %s, subject '%s'", to_email, subject)
from_name = from_name or config.NOREPLY
from_addr = from_addr or config.NOREPLY
from_domain = get_email_domain_part(from_addr)
if html:
msg = MIMEMultipart("alternative")
msg.attach(MIMEText(plaintext))
msg.attach(MIMEText(html, "html"))
else:
msg = EmailMessage()
msg.set_payload(plaintext)
msg[headers.CONTENT_TYPE] = "text/plain"
msg[headers.SUBJECT] = subject
msg[headers.FROM] = f'"{from_name}" <{from_addr}>'
msg[headers.TO] = to_email
msg_id_header = make_msgid(domain=config.EMAIL_DOMAIN)
msg[headers.MESSAGE_ID] = msg_id_header
date_header = formatdate()
msg[headers.DATE] = date_header
if headers.MIME_VERSION not in msg:
msg[headers.MIME_VERSION] = "1.0"
if unsubscribe_link:
add_or_replace_header(msg, headers.LIST_UNSUBSCRIBE, f"<{unsubscribe_link}>")
if not unsubscribe_via_email:
add_or_replace_header(
msg, headers.LIST_UNSUBSCRIBE_POST, "List-Unsubscribe=One-Click"
)
# add DKIM
email_domain = from_addr[from_addr.find("@") + 1 :]
add_dkim_signature(msg, email_domain)
transaction = TransactionalEmail.create(email=to_email, commit=True)
# use a different envelope sender for each transactional email (aka VERP)
sl_sendmail(
generate_verp_email(VerpType.transactional, transaction.id, from_domain),
to_email,
msg,
retries=retries,
ignore_smtp_error=ignore_smtp_error,
)
def send_email_with_rate_control(
user: User,
alert_type: str,
to_email: str,
subject,
plaintext,
html=None,
max_nb_alert=config.MAX_ALERT_24H,
nb_day=1,
ignore_smtp_error=False,
retries=0,
) -> bool:
"""Same as send_email with rate control over alert_type.
Make sure no more than `max_nb_alert` emails are sent over the period of `nb_day` days
Return true if the email is sent, otherwise False
"""
to_email = sanitize_email(to_email)
min_dt = arrow.now().shift(days=-1 * nb_day)
nb_alert = (
SentAlert.filter_by(alert_type=alert_type, to_email=to_email)
.filter(SentAlert.created_at > min_dt)
.count()
)
if nb_alert >= max_nb_alert:
LOG.w(
"%s emails were sent to %s in the last %s days, alert type %s",
nb_alert,
to_email,
nb_day,
alert_type,
)
return False
SentAlert.create(user_id=user.id, alert_type=alert_type, to_email=to_email)
Session.commit()
if ignore_smtp_error:
try:
send_email(to_email, subject, plaintext, html, retries=retries)
except SMTPException:
LOG.w("Cannot send email to %s, subject %s", to_email, subject)
else:
send_email(to_email, subject, plaintext, html, retries=retries)
return True
def send_email_at_most_times(
user: User,
alert_type: str,
to_email: str,
subject,
plaintext,
html=None,
max_times=1,
) -> bool:
"""Same as send_email with rate control over alert_type.
Sent at most `max_times`
This is used to inform users about a warning.
Return true if the email is sent, otherwise False
"""
to_email = sanitize_email(to_email)
nb_alert = SentAlert.filter_by(alert_type=alert_type, to_email=to_email).count()
if nb_alert >= max_times:
LOG.w(
"%s emails were sent to %s alert type %s",
nb_alert,
to_email,
alert_type,
)
return False
SentAlert.create(user_id=user.id, alert_type=alert_type, to_email=to_email)
Session.commit()
send_email(to_email, subject, plaintext, html)
return True
def get_email_local_part(address) -> str:
"""
Get the local part from email
ab@cd.com -> ab
Convert the local part to lowercase
"""
r: ValidatedEmail = validate_email(
address, check_deliverability=False, allow_smtputf8=False
)
return r.local_part.lower()
def get_email_domain_part(address):
"""
Get the domain part from email
ab@cd.com -> cd.com
"""
address = sanitize_email(address)
return address[address.find("@") + 1 :]
def add_dkim_signature(msg: Message, email_domain: str):
if config.RSPAMD_SIGN_DKIM:
LOG.d("DKIM signature will be added by rspamd")
msg[headers.SL_WANT_SIGNING] = "yes"
return
for dkim_headers in headers.DKIM_HEADERS:
try:
add_dkim_signature_with_header(msg, email_domain, dkim_headers)
return
except dkim.DKIMException:
LOG.w("DKIM fail with %s", dkim_headers, exc_info=True)
# try with another headers
continue
# To investigate why some emails can't be DKIM signed. todo: remove
if config.TEMP_DIR:
file_name = str(uuid.uuid4()) + ".eml"
with open(os.path.join(config.TEMP_DIR, file_name), "wb") as f:
f.write(msg.as_bytes())
LOG.w("email saved to %s", file_name)
raise Exception("Cannot create DKIM signature")
def add_dkim_signature_with_header(
msg: Message, email_domain: str, dkim_headers: [bytes]
):
delete_header(msg, "DKIM-Signature")
# Specify headers in "byte" form
# Generate message signature
if config.DKIM_PRIVATE_KEY:
sig = dkim.sign(
message_to_bytes(msg),
config.DKIM_SELECTOR,
email_domain.encode(),
config.DKIM_PRIVATE_KEY.encode(),
include_headers=dkim_headers,
)
sig = sig.decode()
# remove linebreaks from sig
sig = sig.replace("\n", " ").replace("\r", "")
msg[headers.DKIM_SIGNATURE] = sig[len("DKIM-Signature: ") :]
def add_or_replace_header(msg: Message, header: str, value: str):
"""
Remove all occurrences of `header` and add `header` with `value`.
"""
delete_header(msg, header)
msg[header] = value
def delete_header(msg: Message, header: str):
"""a header can appear several times in message."""
# inspired from https://stackoverflow.com/a/47903323/1428034
for i in reversed(range(len(msg._headers))):
header_name = msg._headers[i][0].lower()
if header_name == header.lower():
del msg._headers[i]
def sanitize_header(msg: Message, header: str):
"""remove trailing space and remove linebreak from a header"""
for i in reversed(range(len(msg._headers))):
header_name = msg._headers[i][0].lower()
if header_name == header.lower():
# msg._headers[i] is a tuple like ('From', 'hey@google.com')
if msg._headers[i][1]:
msg._headers[i] = (
msg._headers[i][0],
msg._headers[i][1].strip().replace("\n", " "),
)
def delete_all_headers_except(msg: Message, headers: [str]):
headers = [h.lower() for h in headers]
for i in reversed(range(len(msg._headers))):
header_name = msg._headers[i][0].lower()
if header_name not in headers:
del msg._headers[i]
def can_create_directory_for_address(email_address: str) -> bool:
"""return True if an email ends with one of the alias domains provided by SimpleLogin"""
# not allow creating directory with premium domain
for domain in config.ALIAS_DOMAINS:
if email_address.endswith("@" + domain):
return True
return False
def is_valid_alias_address_domain(email_address) -> bool:
"""Return whether an address domain might a domain handled by SimpleLogin"""
domain = get_email_domain_part(email_address)
if SLDomain.get_by(domain=domain):
return True
if CustomDomain.get_by(domain=domain, verified=True):
return True
return False
def email_can_be_used_as_mailbox(email_address: str) -> bool:
"""Return True if an email can be used as a personal email.
Use the email domain as criteria. A domain can be used if it is not:
- one of ALIAS_DOMAINS
- one of PREMIUM_ALIAS_DOMAINS
- one of custom domains
- a disposable domain
"""
try:
domain = validate_email(
email_address, check_deliverability=False, allow_smtputf8=False
).domain
except EmailNotValidError:
LOG.d("%s is invalid email address", email_address)
return False
if not domain:
LOG.d("no valid domain associated to %s", email_address)
return False
if SLDomain.get_by(domain=domain):
LOG.d("%s is a SL domain", email_address)
return False
from app.models import CustomDomain
if CustomDomain.get_by(domain=domain, verified=True):
LOG.d("domain %s is a SimpleLogin custom domain", domain)
return False
if is_invalid_mailbox_domain(domain):
LOG.d("Domain %s is invalid mailbox domain", domain)
return False
# check if email MX domain is disposable
mx_domains = get_mx_domain_list(domain)
# if no MX record, email is not valid
if not config.SKIP_MX_LOOKUP_ON_CHECK and not mx_domains:
LOG.d("No MX record for domain %s", domain)
return False
for mx_domain in mx_domains:
if is_invalid_mailbox_domain(mx_domain):
LOG.d("MX Domain %s %s is invalid mailbox domain", mx_domain, domain)
return False
return True
def is_invalid_mailbox_domain(domain):
"""
Whether a domain is invalid mailbox domain
Also return True if `domain` is a subdomain of an invalid mailbox domain
"""
parts = domain.split(".")
for i in range(0, len(parts) - 1):
parent_domain = ".".join(parts[i:])
if InvalidMailboxDomain.get_by(domain=parent_domain):
return True
return False
def get_mx_domain_list(domain) -> [str]:
"""return list of MX domains for a given email.
domain name ends *without* a dot (".") at the end.
"""
priority_domains = get_mx_domains(domain)
return [d[:-1] for _, d in priority_domains]
def personal_email_already_used(email_address: str) -> bool:
"""test if an email can be used as user email"""
if User.get_by(email=email_address):
return True
return False
def mailbox_already_used(email: str, user) -> bool:
if Mailbox.get_by(email=email, user_id=user.id):
return True
# support the case user wants to re-add their real email as mailbox
# can happen when user changes their root email and wants to add this new email as mailbox
if email == user.email:
return False
return False
def get_orig_message_from_bounce(bounce_report: Message) -> Optional[Message]:
"""parse the original email from Bounce"""
i = 0
for part in bounce_report.walk():
i += 1
# 1st part is the container (bounce report)
# 2nd part is the report from our own Postfix
# 3rd is report from other mailbox
# 4th is the container of the original message
# ...
# 7th is original message
if i == 7:
return part
def get_mailbox_bounce_info(bounce_report: Message) -> Optional[Message]:
"""
Return the bounce info from the bounce report
An example of bounce info:
Final-Recipient: rfc822; not-existing@gmail.com
Original-Recipient: rfc822;not-existing@gmail.com
Action: failed
Status: 5.1.1
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp;
550-5.1.1 The email account that you tried to reach does
not exist. Please try 550-5.1.1 double-checking the recipient's email
address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1
https://support.google.com/mail/?p=NoSuchUser z127si6173191wmc.132 - gsmtp
"""
i = 0
for part in bounce_report.walk():
i += 1
# 1st part is the container (bounce report)
# 2nd part is the report from our own Postfix
# 3rd is report from other mailbox
# 4th is the container of the original message
# 5th is a child of 3rd that contains more info about the bounce
if i == 5:
if not part["content-transfer-encoding"]:
LOG.w("add missing content-transfer-encoding header")
part["content-transfer-encoding"] = "7bit"
try:
part.as_bytes().decode()
except UnicodeDecodeError:
LOG.w("cannot use this bounce report")
return
else:
return part
def get_header_from_bounce(msg: Message, header: str) -> str:
"""using regex to get header value from bounce message
get_orig_message_from_bounce is better. This should be the last option
"""
msg_str = str(msg)
exp = re.compile(f"{header}.*\n")
r = re.search(exp, msg_str)
if r:
# substr should be something like 'HEADER: 1234'
substr = msg_str[r.start() : r.end()].strip()
parts = substr.split(":")
return parts[1].strip()
return None
def get_orig_message_from_spamassassin_report(msg: Message) -> Message:
"""parse the original email from Spamassassin report"""
i = 0
for part in msg.walk():
i += 1
# the original message is the 4th part
# 1st part is the root part, multipart/report
# 2nd is text/plain, SpamAssassin part
# 3rd is the original message in message/rfc822 content type
# 4th is original message
if i == 4:
return part
def get_spam_info(msg: Message, max_score=None) -> (bool, str):
"""parse SpamAssassin header to detect whether a message is classified as spam.
Return (is spam, spam status detail)
The header format is
```X-Spam-Status: No, score=-0.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
DKIM_VALID_AU,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_PASS,
URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2```
"""
spamassassin_status = msg[headers.X_SPAM_STATUS]
if not spamassassin_status:
return False, ""
return get_spam_from_header(spamassassin_status, max_score=max_score)
def get_spam_from_header(spam_status_header, max_score=None) -> (bool, str):
"""get spam info from X-Spam-Status header
Return (is spam, spam status detail).
The spam_status_header has the following format
```No, score=-0.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
DKIM_VALID_AU,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_PASS,
URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2```
"""
# yes or no
spamassassin_answer = spam_status_header[: spam_status_header.find(",")]
if max_score:
# spam score
# get the score section "score=-0.1"
score_section = (
spam_status_header[spam_status_header.find(",") + 1 :].strip().split(" ")[0]
)
score = float(score_section[len("score=") :])
if score >= max_score:
LOG.w("Spam score %s exceeds %s", score, max_score)
return True, spam_status_header
return spamassassin_answer.lower() == "yes", spam_status_header
def get_header_unicode(header: Union[str, Header]) -> str:
"""
Convert a header to unicode
Should be used to handle headers like From:, To:, CC:, Subject:
"""
if header is None:
return ""
ret = ""
for to_decoded_str, charset in decode_header(header):
if charset is None:
if type(to_decoded_str) is bytes:
decoded_str = to_decoded_str.decode()
else:
decoded_str = to_decoded_str
else:
try:
decoded_str = to_decoded_str.decode(charset)
except (LookupError, UnicodeDecodeError): # charset is unknown
LOG.w("Cannot decode %s with %s, try utf-8", to_decoded_str, charset)
try:
decoded_str = to_decoded_str.decode("utf-8")
except UnicodeDecodeError:
LOG.w("Cannot UTF-8 decode %s", to_decoded_str)
decoded_str = to_decoded_str.decode("utf-8", errors="replace")
ret += decoded_str
return ret
def copy(msg: Message) -> Message:
"""return a copy of message"""
try:
return deepcopy(msg)
except Exception:
LOG.w("deepcopy fails, try string parsing")
try:
return message_from_string(msg.as_string())
except (UnicodeEncodeError, LookupError):
LOG.w("as_string() fails, try bytes parsing")
return message_from_bytes(message_to_bytes(msg))
def to_bytes(msg: Message):
"""replace Message.as_bytes() method by trying different policies"""
for generator_policy in [None, policy.SMTP, policy.SMTPUTF8]:
try:
return msg.as_bytes(policy=generator_policy)
except:
LOG.w("as_bytes() fails with %s policy", policy, exc_info=True)
msg_string = msg.as_string()
try:
return msg_string.encode()
except:
LOG.w("as_string().encode() fails", exc_info=True)
return msg_string.encode(errors="replace")
def should_add_dkim_signature(domain: str) -> bool:
if SLDomain.get_by(domain=domain):
return True
custom_domain: CustomDomain = CustomDomain.get_by(domain=domain)
if custom_domain.dkim_verified:
return True
return False
def is_valid_email(email_address: str) -> bool:
"""
Used to check whether an email address is valid
NOT run MX check.
NOT allow unicode.
"""
try:
validate_email(email_address, check_deliverability=False, allow_smtputf8=False)
return True
except EmailNotValidError:
return False
class EmailEncoding(enum.Enum):
BASE64 = "base64"
QUOTED = "quoted-printable"
NO = "no-encoding"
def get_encoding(msg: Message) -> EmailEncoding:
"""
Return the message encoding, possible values:
- quoted-printable
- base64
- 7bit: default if unknown or empty
"""
cte = (
str(msg.get(headers.CONTENT_TRANSFER_ENCODING, ""))
.lower()
.strip()
.strip('"')
.strip("'")
)
if cte in (
"",
"7bit",
"7-bit",
"7bits",
"8bit",
"8bits",
"binary",
"8bit;",
"utf-8",
):
return EmailEncoding.NO
if cte == "base64":
return EmailEncoding.BASE64
if cte == "quoted-printable":
return EmailEncoding.QUOTED
# some email services use unknown encoding
if cte in ("amazonses.com",):
return EmailEncoding.NO
LOG.e("Unknown encoding %s", cte)
return EmailEncoding.NO
def encode_text(text: str, encoding: EmailEncoding = EmailEncoding.NO) -> str:
if encoding == EmailEncoding.QUOTED:
encoded = quopri.encodestring(text.encode("utf-8"))
return str(encoded, "utf-8")
elif encoding == EmailEncoding.BASE64:
encoded = base64.b64encode(text.encode("utf-8"))
return str(encoded, "utf-8")
else: # 7bit - no encoding
return text
def decode_text(text: str, encoding: EmailEncoding = EmailEncoding.NO) -> str:
if encoding == EmailEncoding.QUOTED:
decoded = quopri.decodestring(text.encode("utf-8"))
return decoded.decode(errors="ignore")
elif encoding == EmailEncoding.BASE64:
decoded = base64.b64decode(text.encode("utf-8"))
return decoded.decode(errors="ignore")
else: # 7bit - no encoding
return text
def add_header(msg: Message, text_header, html_header=None) -> Message:
if not html_header:
html_header = text_header.replace("\n", "<br>")
content_type = msg.get_content_type().lower()
if content_type == "text/plain":
encoding = get_encoding(msg)
payload = msg.get_payload()
if type(payload) is str:
clone_msg = copy(msg)
new_payload = f"""{text_header}
------------------------------
{decode_text(payload, encoding)}"""
clone_msg.set_payload(encode_text(new_payload, encoding))
return clone_msg
elif content_type == "text/html":
encoding = get_encoding(msg)
payload = msg.get_payload()
if type(payload) is str:
new_payload = f"""<table width="100%" style="width: 100%; -premailer-width: 100%; -premailer-cellpadding: 0;
-premailer-cellspacing: 0; margin: 0; padding: 0;">
<tr>
<td style="border-bottom:1px dashed #5675E2; padding: 10px 0px">{html_header}</td>
</tr>
<tr>
<td>
{decode_text(payload, encoding)}
</td>
</tr>
</table>
"""
clone_msg = copy(msg)
clone_msg.set_payload(encode_text(new_payload, encoding))
return clone_msg
elif content_type in ("multipart/alternative", "multipart/related"):
new_parts = []
for part in msg.get_payload():
if isinstance(part, Message):
new_parts.append(add_header(part, text_header, html_header))
else:
new_parts.append(part)
clone_msg = copy(msg)
clone_msg.set_payload(new_parts)
return clone_msg
elif content_type in ("multipart/mixed", "multipart/signed"):
new_parts = []
parts = list(msg.get_payload())
LOG.d("only add header for the first part for %s", content_type)
for ix, part in enumerate(parts):
if ix == 0:
new_parts.append(add_header(part, text_header, html_header))
else:
new_parts.append(part)
clone_msg = copy(msg)
clone_msg.set_payload(new_parts)
return clone_msg
LOG.d("No header added for %s", content_type)
return msg
def replace(msg: Union[Message, str], old, new) -> Union[Message, str]:
if type(msg) is str:
msg = msg.replace(old, new)
return msg
content_type = msg.get_content_type()
if (
content_type.startswith("image/")
or content_type.startswith("video/")
or content_type.startswith("audio/")
or content_type == "multipart/signed"
or content_type.startswith("application/")
or content_type == "text/calendar"
or content_type == "text/directory"
or content_type == "text/csv"
or content_type == "text/x-python-script"
):
LOG.d("not applicable for %s", content_type)
return msg
if content_type in ("text/plain", "text/html"):
encoding = get_encoding(msg)
payload = msg.get_payload()
if type(payload) is str:
if encoding == EmailEncoding.QUOTED:
LOG.d("handle quoted-printable replace %s -> %s", old, new)
# first decode the payload
try:
new_payload = quopri.decodestring(payload).decode("utf-8")
except UnicodeDecodeError:
LOG.w("cannot decode payload:%s", payload)
return msg
# then replace the old text
new_payload = new_payload.replace(old, new)
clone_msg = copy(msg)
clone_msg.set_payload(quopri.encodestring(new_payload.encode()))
return clone_msg
elif encoding == EmailEncoding.BASE64:
new_payload = decode_text(payload, encoding).replace(old, new)
new_payload = base64.b64encode(new_payload.encode("utf-8"))
clone_msg = copy(msg)
clone_msg.set_payload(new_payload)
return clone_msg
else:
clone_msg = copy(msg)
new_payload = payload.replace(
encode_text(old, encoding), encode_text(new, encoding)
)
clone_msg.set_payload(new_payload)
return clone_msg
elif content_type in (
"multipart/alternative",
"multipart/related",
"multipart/mixed",
"message/rfc822",
):
new_parts = []
for part in msg.get_payload():
new_parts.append(replace(part, old, new))
clone_msg = copy(msg)
clone_msg.set_payload(new_parts)
return clone_msg
LOG.w("Cannot replace text for %s", msg.get_content_type())
return msg
def generate_reply_email(contact_email: str, user: User) -> str:
"""
generate a reply_email (aka reverse-alias), make sure it isn't used by any contact
"""
# shorten email to avoid exceeding the 64 characters
# from https://tools.ietf.org/html/rfc5321#section-4.5.3
# "The maximum total length of a user name or other local-part is 64
# octets."
include_sender_in_reverse_alias = False
# user has set this option explicitly
if user.include_sender_in_reverse_alias is not None:
include_sender_in_reverse_alias = user.include_sender_in_reverse_alias
if include_sender_in_reverse_alias and contact_email:
# make sure contact_email can be ascii-encoded
contact_email = convert_to_id(contact_email)
contact_email = sanitize_email(contact_email)
contact_email = contact_email[:45]
# use _ instead of . to avoid AC_FROM_MANY_DOTS SpamAssassin rule
contact_email = contact_email.replace("@", "_at_")
contact_email = contact_email.replace(".", "_")
contact_email = convert_to_alphanumeric(contact_email)
# not use while to avoid infinite loop
for _ in range(1000):
if include_sender_in_reverse_alias and contact_email:
random_length = random.randint(5, 10)
reply_email = (
# do not use the ra+ anymore
# f"ra+{contact_email}+{random_string(random_length)}@{config.EMAIL_DOMAIN}"
f"{contact_email}_{random_string(random_length)}@{config.EMAIL_DOMAIN}"
)
else:
random_length = random.randint(20, 50)
# do not use the ra+ anymore
# reply_email = f"ra+{random_string(random_length)}@{config.EMAIL_DOMAIN}"
reply_email = f"{random_string(random_length)}@{config.EMAIL_DOMAIN}"
if not Contact.get_by(reply_email=reply_email):
return reply_email
raise Exception("Cannot generate reply email")
def is_reverse_alias(address: str) -> bool:
# to take into account the new reverse-alias that doesn't start with "ra+"
if Contact.get_by(reply_email=address):
return True
return address.endswith(f"@{config.EMAIL_DOMAIN}") and (
address.startswith("reply+") or address.startswith("ra+")
)
# allow also + and @ that are present in a reply address
_ALLOWED_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-.+@"
def normalize_reply_email(reply_email: str) -> str:
"""Handle the case where reply email contains *strange* char that was wrongly generated in the past"""
if not reply_email.isascii():
reply_email = convert_to_id(reply_email)
ret = []
# drop all control characters like shift, separator, etc
for c in reply_email:
if c not in _ALLOWED_CHARS:
ret.append("_")
else:
ret.append(c)
return "".join(ret)
def should_disable(alias: Alias) -> (bool, str):
"""
Return whether an alias should be disabled and if yes, the reason why
"""
# Bypass the bounce rule
if alias.cannot_be_disabled:
LOG.w("%s cannot be disabled", alias)
return False, ""
if not config.ALIAS_AUTOMATIC_DISABLE:
return False, ""
yesterday = arrow.now().shift(days=-1)
nb_bounced_last_24h = (
Session.query(EmailLog)
.filter(
EmailLog.bounced.is_(True),
EmailLog.is_reply.is_(False),
EmailLog.created_at > yesterday,
)
.filter(EmailLog.alias_id == alias.id)
.count()
)
# if more than 12 bounces in 24h -> disable alias
if nb_bounced_last_24h > 12:
return True, "+12 bounces in the last 24h"
# if more than 5 bounces but has +10 bounces last week -> disable alias
elif nb_bounced_last_24h > 5:
one_week_ago = arrow.now().shift(days=-7)
nb_bounced_7d_1d = (
Session.query(EmailLog)
.filter(
EmailLog.bounced.is_(True),
EmailLog.is_reply.is_(False),
EmailLog.created_at > one_week_ago,
EmailLog.created_at < yesterday,
)
.filter(EmailLog.alias_id == alias.id)
.count()
)
if nb_bounced_7d_1d > 10:
return (
True,
"+5 bounces in the last 24h and +10 bounces in the last 7 days",
)
else:
# alias level
# if bounces happen for at least 9 days in the last 10 days -> disable alias
query = (
Session.query(
func.date(EmailLog.created_at).label("date"),
func.count(EmailLog.id).label("count"),
)
.filter(EmailLog.alias_id == alias.id)
.filter(
EmailLog.created_at > arrow.now().shift(days=-10),
EmailLog.bounced.is_(True),
EmailLog.is_reply.is_(False),
)
.group_by("date")
)
if query.count() >= 9:
return True, "Bounces every day for at least 9 days in the last 10 days"
# account level
query = (
Session.query(
func.date(EmailLog.created_at).label("date"),
func.count(EmailLog.id).label("count"),
)
.filter(EmailLog.user_id == alias.user_id)
.filter(
EmailLog.created_at > arrow.now().shift(days=-10),
EmailLog.bounced.is_(True),
EmailLog.is_reply.is_(False),
)
.group_by("date")
)
# if an account has more than 10 bounces every day for at least 4 days in the last 10 days, disable alias
date_bounces: List[Tuple[arrow.Arrow, int]] = list(query)
more_than_10_bounces = [
(d, nb_bounce) for d, nb_bounce in date_bounces if nb_bounce > 10
]
if len(more_than_10_bounces) > 4:
return True, "+10 bounces for +4 days in the last 10 days"
return False, ""
def parse_id_from_bounce(email_address: str) -> int:
return int(email_address[email_address.find("+") : email_address.rfind("+")])
def spf_pass(
envelope,
mailbox: Mailbox,
user: User,
alias: Alias,
contact_email: str,
msg: Message,
) -> bool:
ip = msg[headers.SL_CLIENT_IP]
if ip:
LOG.d("Enforce SPF on %s %s", ip, envelope.mail_from)
try:
r = spf.check2(i=ip, s=envelope.mail_from, h=None)
except Exception:
LOG.e("SPF error, mailbox %s, ip %s", mailbox.email, ip)
else:
# TODO: Handle temperr case (e.g. dns timeout)
# only an absolute pass, or no SPF policy at all is 'valid'
if r[0] not in ["pass", "none"]:
LOG.w(
"SPF fail for mailbox %s, reason %s, failed IP %s",
mailbox.email,
r[0],
ip,
)
subject = get_header_unicode(msg[headers.SUBJECT])
send_email_with_rate_control(
user,
config.ALERT_SPF,
mailbox.email,
f"SimpleLogin Alert: attempt to send emails from your alias {alias.email} from unknown IP Address",
render(
"transactional/spf-fail.txt",
alias=alias.email,
ip=ip,
mailbox_url=config.URL + f"/dashboard/mailbox/{mailbox.id}#spf",
to_email=contact_email,
subject=subject,
time=arrow.now(),
),
render(
"transactional/spf-fail.html",
ip=ip,
mailbox_url=config.URL + f"/dashboard/mailbox/{mailbox.id}#spf",
to_email=contact_email,
subject=subject,
time=arrow.now(),
),
)
return False
else:
LOG.w(
"Could not find %s header %s -> %s",
headers.SL_CLIENT_IP,
mailbox.email,
contact_email,
)
return True
# cache the smtp server for 20 seconds
@cached(cache=TTLCache(maxsize=2, ttl=20))
def get_smtp_server():
LOG.d("get a smtp server")
if config.POSTFIX_SUBMISSION_TLS:
smtp = SMTP(config.POSTFIX_SERVER, 587)
smtp.starttls()
else:
smtp = SMTP(config.POSTFIX_SERVER, config.POSTFIX_PORT)
return smtp
def get_queue_id(msg: Message) -> Optional[str]:
"""Get the Postfix queue-id from a message"""
header_values = msg.get_all(headers.RSPAMD_QUEUE_ID)
if header_values:
# Get last in case somebody tries to inject a header
return header_values[-1]
received_header = str(msg[headers.RECEIVED])
if not received_header:
return
# received_header looks like 'from mail-wr1-x434.google.com (mail-wr1-x434.google.com [IPv6:2a00:1450:4864:20::434])\r\n\t(using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits))\r\n\t(No client certificate requested)\r\n\tby mx1.simplelogin.co (Postfix) with ESMTPS id 4FxQmw1DXdz2vK2\r\n\tfor <jglfdjgld@alias.com>; Fri, 4 Jun 2021 14:55:43 +0000 (UTC)'
search_result = re.search("with ESMTPS id [0-9a-zA-Z]{1,}", received_header)
if not search_result:
return
# the "with ESMTPS id 4FxQmw1DXdz2vK2" part
with_esmtps = received_header[search_result.start() : search_result.end()]
return with_esmtps[len("with ESMTPS id ") :]
def should_ignore_bounce(mail_from: str) -> bool:
if IgnoreBounceSender.get_by(mail_from=mail_from):
LOG.w("do not send back bounce report to %s", mail_from)
return True
return False
def parse_address_list(address_list: str) -> List[Tuple[str, str]]:
"""
Parse a list of email addresses from a header in the form "ab <ab@sd.com>, cd <cd@cd.com>"
and return a list [("ab", "ab@sd.com"),("cd", "cd@cd.com")]
"""
processed_addresses = []
for split_address in address_list.split(","):
split_address = split_address.strip()
if not split_address:
continue
processed_addresses.append(parse_full_address(split_address))
return processed_addresses
def parse_full_address(full_address) -> (str, str):
"""
parse the email address full format and return the display name and address
For ex: ab <cd@xy.com> -> (ab, cd@xy.com)
'=?UTF-8?B?TmjGoW4gTmd1eeG7hW4=?= <abcd@gmail.com>' -> ('Nhơn Nguyễn', "abcd@gmail.com")
If the parsing fails, raise ValueError
"""
full_address: EmailAddress = address.parse(full_address)
if full_address is None:
raise ValueError
# address.parse can also parse a URL and return UrlAddress
if type(full_address) is not EmailAddress:
raise ValueError
return full_address.display_name, full_address.address
def save_email_for_debugging(msg: Message, file_name_prefix=None) -> str:
"""Save email for debugging to temporary location
Return the file path
"""
if config.TEMP_DIR:
file_name = str(uuid.uuid4()) + ".eml"
if file_name_prefix:
file_name = "{}-{}".format(file_name_prefix, file_name)
with open(os.path.join(config.TEMP_DIR, file_name), "wb") as f:
f.write(msg.as_bytes())
LOG.d("email saved to %s", file_name)
return file_name
return ""
def save_envelope_for_debugging(envelope: Envelope, file_name_prefix=None) -> str:
"""Save envelope for debugging to temporary location
Return the file path
"""
if config.TEMP_DIR:
file_name = str(uuid.uuid4()) + ".eml"
if file_name_prefix:
file_name = "{}-{}".format(file_name_prefix, file_name)
with open(os.path.join(config.TEMP_DIR, file_name), "wb") as f:
f.write(envelope.original_content)
LOG.d("envelope saved to %s", file_name)
return file_name
return ""
def generate_verp_email(
verp_type: VerpType, object_id: int, sender_domain: Optional[str] = None
) -> str:
"""Generates an email address with the verp type, object_id and domain encoded in the address
and signed with hmac to prevent tampering
"""
# Encoded as a list to minimize size of email address
# Time is in minutes granularity and start counting on 2022-01-01 to reduce bytes to represent time
data = [
verp_type.value,
object_id,
int((time.time() - VERP_TIME_START) / 60),
]
json_payload = json.dumps(data).encode("utf-8")
# Signing without itsdangereous because it uses base64 that includes +/= symbols and lower and upper case letters.
# We need to encode in base32
payload_hmac = hmac.new(
config.VERP_EMAIL_SECRET.encode("utf-8"), json_payload, VERP_HMAC_ALGO
).digest()[:8]
encoded_payload = base64.b32encode(json_payload).rstrip(b"=").decode("utf-8")
encoded_signature = base64.b32encode(payload_hmac).rstrip(b"=").decode("utf-8")
return "{}.{}.{}@{}".format(
config.VERP_PREFIX,
encoded_payload,
encoded_signature,
sender_domain or config.EMAIL_DOMAIN,
).lower()
def get_verp_info_from_email(email: str) -> Optional[Tuple[VerpType, int]]:
"""This method processes the email address, checks if it's a signed verp email generated by us to receive bounces
and extracts the type of verp email and associated email log id/transactional email id stored as object_id
"""
idx = email.find("@")
if idx == -1:
return None
username = email[:idx]
fields = username.split(".")
if len(fields) != 3 or fields[0] != config.VERP_PREFIX:
return None
try:
padding = (8 - (len(fields[1]) % 8)) % 8
payload = base64.b32decode(fields[1].encode("utf-8").upper() + (b"=" * padding))
padding = (8 - (len(fields[2]) % 8)) % 8
signature = base64.b32decode(
fields[2].encode("utf-8").upper() + (b"=" * padding)
)
except binascii.Error:
return None
expected_signature = hmac.new(
config.VERP_EMAIL_SECRET.encode("utf-8"), payload, VERP_HMAC_ALGO
).digest()[:8]
if expected_signature != signature:
return None
data = json.loads(payload)
# verp type, object_id, time
if len(data) != 3:
return None
if data[2] > (time.time() + config.VERP_MESSAGE_LIFETIME - VERP_TIME_START) / 60:
return None
return VerpType(data[0]), data[1]
def sl_formataddr(name_address_tuple: Tuple[str, str]):
"""Same as formataddr but use utf-8 encoding by default and always return str (and never Header)"""
name, addr = name_address_tuple
# formataddr can return Header, make sure to convert to str
return str(formataddr((name, Header(addr, "utf-8"))))
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