????
Your IP : 216.73.216.1
from .exceptions_types import EmailSyntaxError
from .rfc_constants import EMAIL_MAX_LENGTH, LOCAL_PART_MAX_LENGTH, DOMAIN_MAX_LENGTH, \
DOT_ATOM_TEXT, DOT_ATOM_TEXT_INTL, ATEXT_RE, ATEXT_INTL_RE, ATEXT_HOSTNAME_INTL, QTEXT_INTL, \
DNS_LABEL_LENGTH_LIMIT, DOT_ATOM_TEXT_HOSTNAME, DOMAIN_NAME_REGEX, DOMAIN_LITERAL_CHARS, \
QUOTED_LOCAL_PART_ADDR
import re
import unicodedata
import idna # implements IDNA 2008; Python's codec is only IDNA 2003
import ipaddress
from typing import Optional
def split_email(email):
# Return the local part and domain part of the address and
# whether the local part was quoted as a three-tuple.
# Typical email addresses have a single @-sign, but the
# awkward "quoted string" local part form (RFC 5321 4.1.2)
# allows @-signs (and escaped quotes) to appear in the local
# part if the local part is quoted. If the address is quoted,
# split it at a non-escaped @-sign and unescape the escaping.
if m := QUOTED_LOCAL_PART_ADDR.match(email):
local_part, domain_part = m.groups()
# Since backslash-escaping is no longer needed because
# the quotes are removed, remove backslash-escaping
# to return in the normalized form.
local_part = re.sub(r"\\(.)", "\\1", local_part)
return local_part, domain_part, True
else:
# Split at the one and only at-sign.
parts = email.split('@')
if len(parts) != 2:
raise EmailSyntaxError("The email address is not valid. It must have exactly one @-sign.")
local_part, domain_part = parts
return local_part, domain_part, False
def get_length_reason(addr, utf8=False, limit=EMAIL_MAX_LENGTH):
"""Helper function to return an error message related to invalid length."""
diff = len(addr) - limit
prefix = "at least " if utf8 else ""
suffix = "s" if diff > 1 else ""
return f"({prefix}{diff} character{suffix} too many)"
def safe_character_display(c):
# Return safely displayable characters in quotes.
if c == '\\':
return f"\"{c}\"" # can't use repr because it escapes it
if unicodedata.category(c)[0] in ("L", "N", "P", "S"):
return repr(c)
# Construct a hex string in case the unicode name doesn't exist.
if ord(c) < 0xFFFF:
h = f"U+{ord(c):04x}".upper()
else:
h = f"U+{ord(c):08x}".upper()
# Return the character name or, if it has no name, the hex string.
return unicodedata.name(c, h)
def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_empty_local: bool = False,
quoted_local_part: bool = False):
"""Validates the syntax of the local part of an email address."""
if len(local) == 0:
if not allow_empty_local:
raise EmailSyntaxError("There must be something before the @-sign.")
# The caller allows an empty local part. Useful for validating certain
# Postfix aliases.
return {
"local_part": local,
"ascii_local_part": local,
"smtputf8": False,
}
# Check the length of the local part by counting characters.
# (RFC 5321 4.5.3.1.1)
# We're checking the number of characters here. If the local part
# is ASCII-only, then that's the same as bytes (octets). If it's
# internationalized, then the UTF-8 encoding may be longer, but
# that may not be relevant. We will check the total address length
# instead.
if len(local) > LOCAL_PART_MAX_LENGTH:
reason = get_length_reason(local, limit=LOCAL_PART_MAX_LENGTH)
raise EmailSyntaxError(f"The email address is too long before the @-sign {reason}.")
# Check the local part against the non-internationalized regular expression.
# Most email addresses match this regex so it's probably fastest to check this first.
# (RFC 5322 3.2.3)
# All local parts matching the dot-atom rule are also valid as a quoted string
# so if it was originally quoted (quoted_local_part is True) and this regex matches,
# it's ok.
# (RFC 5321 4.1.2 / RFC 5322 3.2.4).
if DOT_ATOM_TEXT.match(local):
# It's valid. And since it's just the permitted ASCII characters,
# it's normalized and safe. If the local part was originally quoted,
# the quoting was unnecessary and it'll be returned as normalized to
# non-quoted form.
# Return the local part and flag that SMTPUTF8 is not needed.
return {
"local_part": local,
"ascii_local_part": local,
"smtputf8": False,
}
# The local part failed the basic dot-atom check. Try the extended character set
# for internationalized addresses. It's the same pattern but with additional
# characters permitted.
# RFC 6531 section 3.3.
valid: Optional[str] = None
requires_smtputf8 = False
if DOT_ATOM_TEXT_INTL.match(local):
# But international characters in the local part may not be permitted.
if not allow_smtputf8:
# Check for invalid characters against the non-internationalized
# permitted character set.
# (RFC 5322 3.2.3)
bad_chars = {
safe_character_display(c)
for c in local
if not ATEXT_RE.match(c)
}
if bad_chars:
raise EmailSyntaxError("Internationalized characters before the @-sign are not supported: " + ", ".join(sorted(bad_chars)) + ".")
# Although the check above should always find something, fall back to this just in case.
raise EmailSyntaxError("Internationalized characters before the @-sign are not supported.")
# It's valid.
valid = "dot-atom"
requires_smtputf8 = True
# There are no syntactic restrictions on quoted local parts, so if
# it was originally quoted, it is probably valid. More characters
# are allowed, like @-signs, spaces, and quotes, and there are no
# restrictions on the placement of dots, as in dot-atom local parts.
elif quoted_local_part:
# Check for invalid characters in a quoted string local part.
# (RFC 5321 4.1.2. RFC 5322 lists additional permitted *obsolete*
# characters which are *not* allowed here. RFC 6531 section 3.3
# extends the range to UTF8 strings.)
bad_chars = {
safe_character_display(c)
for c in local
if not QTEXT_INTL.match(c)
}
if bad_chars:
raise EmailSyntaxError("The email address contains invalid characters in quotes before the @-sign: " + ", ".join(sorted(bad_chars)) + ".")
# See if any characters are outside of the ASCII range.
bad_chars = {
safe_character_display(c)
for c in local
if not (32 <= ord(c) <= 126)
}
if bad_chars:
requires_smtputf8 = True
# International characters in the local part may not be permitted.
if not allow_smtputf8:
raise EmailSyntaxError("Internationalized characters before the @-sign are not supported: " + ", ".join(sorted(bad_chars)) + ".")
# It's valid.
valid = "quoted"
# If the local part matches the internationalized dot-atom form or was quoted,
# perform normalization and additional checks for Unicode strings.
if valid:
# RFC 6532 section 3.1 says that Unicode NFC normalization should be applied,
# so we'll return the normalized local part in the return value.
local = unicodedata.normalize("NFC", local)
# Check that the local part is a valid, safe, and sensible Unicode string.
# Some of this may be redundant with the range U+0080 to U+10FFFF that is checked
# by DOT_ATOM_TEXT_INTL and QTEXT_INTL. Other characters may be permitted by the
# email specs, but they may not be valid, safe, or sensible Unicode strings.
# See the function for rationale.
check_unsafe_chars(local, allow_space=(valid == "quoted"))
# Try encoding to UTF-8. Failure is possible with some characters like
# surrogate code points, but those are checked above. Still, we don't
# want to have an unhandled exception later.
try:
local.encode("utf8")
except ValueError as e:
raise EmailSyntaxError("The email address contains an invalid character.") from e
# If this address passes only by the quoted string form, re-quote it
# and backslash-escape quotes and backslashes (removing any unnecessary
# escapes). Per RFC 5321 4.1.2, "all quoted forms MUST be treated as equivalent,
# and the sending system SHOULD transmit the form that uses the minimum quoting possible."
if valid == "quoted":
local = '"' + re.sub(r'(["\\])', r'\\\1', local) + '"'
return {
"local_part": local,
"ascii_local_part": local if not requires_smtputf8 else None,
"smtputf8": requires_smtputf8,
}
# It's not a valid local part. Let's find out why.
# (Since quoted local parts are all valid or handled above, these checks
# don't apply in those cases.)
# Check for invalid characters.
# (RFC 5322 3.2.3, plus RFC 6531 3.3)
bad_chars = {
safe_character_display(c)
for c in local
if not ATEXT_INTL_RE.match(c)
}
if bad_chars:
raise EmailSyntaxError("The email address contains invalid characters before the @-sign: " + ", ".join(sorted(bad_chars)) + ".")
# Check for dot errors imposted by the dot-atom rule.
# (RFC 5322 3.2.3)
check_dot_atom(local, 'An email address cannot start with a {}.', 'An email address cannot have a {} immediately before the @-sign.', is_hostname=False)
# All of the reasons should already have been checked, but just in case
# we have a fallback message.
raise EmailSyntaxError("The email address contains invalid characters before the @-sign.")
def check_unsafe_chars(s, allow_space=False):
# Check for unsafe characters or characters that would make the string
# invalid or non-sensible Unicode.
bad_chars = set()
for i, c in enumerate(s):
category = unicodedata.category(c)
if category[0] in ("L", "N", "P", "S"):
# Letters, numbers, punctuation, and symbols are permitted.
pass
elif category[0] == "M":
# Combining character in first position would combine with something
# outside of the email address if concatenated, so they are not safe.
# We also check if this occurs after the @-sign, which would not be
# sensible.
if i == 0:
bad_chars.add(c)
elif category == "Zs":
# Spaces outside of the ASCII range are not specifically disallowed in
# internationalized addresses as far as I can tell, but they violate
# the spirit of the non-internationalized specification that email
# addresses do not contain ASCII spaces when not quoted. Excluding
# ASCII spaces when not quoted is handled directly by the atom regex.
#
# In quoted-string local parts, spaces are explicitly permitted, and
# the ASCII space has category Zs, so we must allow it here, and we'll
# allow all Unicode spaces to be consistent.
if not allow_space:
bad_chars.add(c)
elif category[0] == "Z":
# The two line and paragraph separator characters (in categories Zl and Zp)
# are not specifically disallowed in internationalized addresses
# as far as I can tell, but they violate the spirit of the non-internationalized
# specification that email addresses do not contain line breaks when not quoted.
bad_chars.add(c)
elif category[0] == "C":
# Control, format, surrogate, private use, and unassigned code points (C)
# are all unsafe in various ways. Control and format characters can affect
# text rendering if the email address is concatenated with other text.
# Bidirectional format characters are unsafe, even if used properly, because
# they cause an email address to render as a different email address.
# Private use characters do not make sense for publicly deliverable
# email addresses.
bad_chars.add(c)
else:
# All categories should be handled above, but in case there is something new
# to the Unicode specification in the future, reject all other categories.
bad_chars.add(c)
if bad_chars:
raise EmailSyntaxError("The email address contains unsafe characters: "
+ ", ".join(safe_character_display(c) for c in sorted(bad_chars)) + ".")
def check_dot_atom(label, start_descr, end_descr, is_hostname):
# RFC 5322 3.2.3
if label.endswith("."):
raise EmailSyntaxError(end_descr.format("period"))
if label.startswith("."):
raise EmailSyntaxError(start_descr.format("period"))
if ".." in label:
raise EmailSyntaxError("An email address cannot have two periods in a row.")
if is_hostname:
# RFC 952
if label.endswith("-"):
raise EmailSyntaxError(end_descr.format("hyphen"))
if label.startswith("-"):
raise EmailSyntaxError(start_descr.format("hyphen"))
if ".-" in label or "-." in label:
raise EmailSyntaxError("An email address cannot have a period and a hyphen next to each other.")
def validate_email_domain_name(domain, test_environment=False, globally_deliverable=True):
"""Validates the syntax of the domain part of an email address."""
# Check for invalid characters before normalization.
# (RFC 952 plus RFC 6531 section 3.3 for internationalized addresses)
bad_chars = {
safe_character_display(c)
for c in domain
if not ATEXT_HOSTNAME_INTL.match(c)
}
if bad_chars:
raise EmailSyntaxError("The part after the @-sign contains invalid characters: " + ", ".join(sorted(bad_chars)) + ".")
# Check for unsafe characters.
# Some of this may be redundant with the range U+0080 to U+10FFFF that is checked
# by DOT_ATOM_TEXT_INTL. Other characters may be permitted by the email specs, but
# they may not be valid, safe, or sensible Unicode strings.
check_unsafe_chars(domain)
# Perform UTS-46 normalization, which includes casefolding, NFC normalization,
# and converting all label separators (the period/full stop, fullwidth full stop,
# ideographic full stop, and halfwidth ideographic full stop) to regular dots.
# It will also raise an exception if there is an invalid character in the input,
# such as "⒈" which is invalid because it would expand to include a dot.
# Since several characters are normalized to a dot, this has to come before
# checks related to dots, like check_dot_atom which comes next.
try:
domain = idna.uts46_remap(domain, std3_rules=False, transitional=False)
except idna.IDNAError as e:
raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).") from e
# The domain part is made up dot-separated "labels." Each label must
# have at least one character and cannot start or end with dashes, which
# means there are some surprising restrictions on periods and dashes.
# Check that before we do IDNA encoding because the IDNA library gives
# unfriendly errors for these cases, but after UTS-46 normalization because
# it can insert periods and hyphens (from fullwidth characters).
# (RFC 952, RFC 1123 2.1, RFC 5322 3.2.3)
check_dot_atom(domain, 'An email address cannot have a {} immediately after the @-sign.', 'An email address cannot end with a {}.', is_hostname=True)
# Check for RFC 5890's invalid R-LDH labels, which are labels that start
# with two characters other than "xn" and two dashes.
for label in domain.split("."):
if re.match(r"(?!xn)..--", label, re.I):
raise EmailSyntaxError("An email address cannot have two letters followed by two dashes immediately after the @-sign or after a period, except Punycode.")
if DOT_ATOM_TEXT_HOSTNAME.match(domain):
# This is a valid non-internationalized domain.
ascii_domain = domain
else:
# If international characters are present in the domain name, convert
# the domain to IDNA ASCII. If internationalized characters are present,
# the MTA must either support SMTPUTF8 or the mail client must convert the
# domain name to IDNA before submission.
#
# Unfortunately this step incorrectly 'fixes' domain names with leading
# periods by removing them, so we have to check for this above. It also gives
# a funky error message ("No input") when there are two periods in a
# row, also checked separately above.
#
# For ASCII-only domains, the transformation does nothing and is safe to
# apply. However, to ensure we don't rely on the idna library for basic
# syntax checks, we don't use it if it's not needed.
#
# uts46 is off here because it is handled above.
try:
ascii_domain = idna.encode(domain, uts46=False).decode("ascii")
except idna.IDNAError as e:
if "Domain too long" in str(e):
# We can't really be more specific because UTS-46 normalization means
# the length check is applied to a string that is different from the
# one the user supplied. Also I'm not sure if the length check applies
# to the internationalized form, the IDNA ASCII form, or even both!
raise EmailSyntaxError("The email address is too long after the @-sign.") from e
# Other errors seem to not be possible because the call to idna.uts46_remap
# would have already raised them.
raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).") from e
# Check the syntax of the string returned by idna.encode.
# It should never fail.
if not DOT_ATOM_TEXT_HOSTNAME.match(ascii_domain):
raise EmailSyntaxError("The email address contains invalid characters after the @-sign after IDNA encoding.")
# Check the length of the domain name in bytes.
# (RFC 1035 2.3.4 and RFC 5321 4.5.3.1.2)
# We're checking the number of bytes ("octets") here, which can be much
# higher than the number of characters in internationalized domains,
# on the assumption that the domain may be transmitted without SMTPUTF8
# as IDNA ASCII. (This is also checked by idna.encode, so this exception
# is never reached for internationalized domains.)
if len(ascii_domain) > DOMAIN_MAX_LENGTH:
reason = get_length_reason(ascii_domain, limit=DOMAIN_MAX_LENGTH)
raise EmailSyntaxError(f"The email address is too long after the @-sign {reason}.")
# Also check the label length limit.
# (RFC 1035 2.3.1)
for label in ascii_domain.split("."):
if len(label) > DNS_LABEL_LENGTH_LIMIT:
reason = get_length_reason(label, limit=DNS_LABEL_LENGTH_LIMIT)
raise EmailSyntaxError(f"After the @-sign, periods cannot be separated by so many characters {reason}.")
if globally_deliverable:
# All publicly deliverable addresses have domain names with at least
# one period, at least for gTLDs created since 2013 (per the ICANN Board
# New gTLD Program Committee, https://www.icann.org/en/announcements/details/new-gtld-dotless-domain-names-prohibited-30-8-2013-en).
# We'll consider the lack of a period a syntax error
# since that will match people's sense of what an email address looks
# like. We'll skip this in test environments to allow '@test' email
# addresses.
if "." not in ascii_domain and not (ascii_domain == "test" and test_environment):
raise EmailSyntaxError("The part after the @-sign is not valid. It should have a period.")
# We also know that all TLDs currently end with a letter.
if not DOMAIN_NAME_REGEX.search(ascii_domain):
raise EmailSyntaxError("The part after the @-sign is not valid. It is not within a valid top-level domain.")
# Check special-use and reserved domain names.
# Some might fail DNS-based deliverability checks, but that
# can be turned off, so we should fail them all sooner.
# See the references in __init__.py.
from . import SPECIAL_USE_DOMAIN_NAMES
for d in SPECIAL_USE_DOMAIN_NAMES:
# See the note near the definition of SPECIAL_USE_DOMAIN_NAMES.
if d == "test" and test_environment:
continue
if ascii_domain == d or ascii_domain.endswith("." + d):
raise EmailSyntaxError("The part after the @-sign is a special-use or reserved name that cannot be used with email.")
# We may have been given an IDNA ASCII domain to begin with. Check
# that the domain actually conforms to IDNA. It could look like IDNA
# but not be actual IDNA. For ASCII-only domains, the conversion out
# of IDNA just gives the same thing back.
#
# This gives us the canonical internationalized form of the domain.
try:
domain_i18n = idna.decode(ascii_domain.encode('ascii'))
except idna.IDNAError as e:
raise EmailSyntaxError(f"The part after the @-sign is not valid IDNA ({e}).") from e
# Check for invalid characters after normalization. These
# should never arise. See the similar checks above.
bad_chars = {
safe_character_display(c)
for c in domain
if not ATEXT_HOSTNAME_INTL.match(c)
}
if bad_chars:
raise EmailSyntaxError("The part after the @-sign contains invalid characters: " + ", ".join(sorted(bad_chars)) + ".")
check_unsafe_chars(domain)
# Return the IDNA ASCII-encoded form of the domain, which is how it
# would be transmitted on the wire (except when used with SMTPUTF8
# possibly), as well as the canonical Unicode form of the domain,
# which is better for display purposes. This should also take care
# of RFC 6532 section 3.1's suggestion to apply Unicode NFC
# normalization to addresses.
return {
"ascii_domain": ascii_domain,
"domain": domain_i18n,
}
def validate_email_length(addrinfo):
# If the email address has an ASCII representation, then we assume it may be
# transmitted in ASCII (we can't assume SMTPUTF8 will be used on all hops to
# the destination) and the length limit applies to ASCII characters (which is
# the same as octets). The number of characters in the internationalized form
# may be many fewer (because IDNA ASCII is verbose) and could be less than 254
# Unicode characters, and of course the number of octets over the limit may
# not be the number of characters over the limit, so if the email address is
# internationalized, we can't give any simple information about why the address
# is too long.
if addrinfo.ascii_email and len(addrinfo.ascii_email) > EMAIL_MAX_LENGTH:
if addrinfo.ascii_email == addrinfo.normalized:
reason = get_length_reason(addrinfo.ascii_email)
elif len(addrinfo.normalized) > EMAIL_MAX_LENGTH:
# If there are more than 254 characters, then the ASCII
# form is definitely going to be too long.
reason = get_length_reason(addrinfo.normalized, utf8=True)
else:
reason = "(when converted to IDNA ASCII)"
raise EmailSyntaxError(f"The email address is too long {reason}.")
# In addition, check that the UTF-8 encoding (i.e. not IDNA ASCII and not
# Unicode characters) is at most 254 octets. If the addres is transmitted using
# SMTPUTF8, then the length limit probably applies to the UTF-8 encoded octets.
# If the email address has an ASCII form that differs from its internationalized
# form, I don't think the internationalized form can be longer, and so the ASCII
# form length check would be sufficient. If there is no ASCII form, then we have
# to check the UTF-8 encoding. The UTF-8 encoding could be up to about four times
# longer than the number of characters.
#
# See the length checks on the local part and the domain.
if len(addrinfo.normalized.encode("utf8")) > EMAIL_MAX_LENGTH:
if len(addrinfo.normalized) > EMAIL_MAX_LENGTH:
# If there are more than 254 characters, then the UTF-8
# encoding is definitely going to be too long.
reason = get_length_reason(addrinfo.normalized, utf8=True)
else:
reason = "(when encoded in bytes)"
raise EmailSyntaxError(f"The email address is too long {reason}.")
def validate_email_domain_literal(domain_literal):
# This is obscure domain-literal syntax. Parse it and return
# a compressed/normalized address.
# RFC 5321 4.1.3 and RFC 5322 3.4.1.
# Try to parse the domain literal as an IPv4 address.
# There is no tag for IPv4 addresses, so we can never
# be sure if the user intends an IPv4 address.
if re.match(r"^[0-9\.]+$", domain_literal):
try:
addr = ipaddress.IPv4Address(domain_literal)
except ValueError as e:
raise EmailSyntaxError(f"The address in brackets after the @-sign is not valid: It is not an IPv4 address ({e}) or is missing an address literal tag.") from e
# Return the IPv4Address object and the domain back unchanged.
return {
"domain_address": addr,
"domain": f"[{addr}]",
}
# If it begins with "IPv6:" it's an IPv6 address.
if domain_literal.startswith("IPv6:"):
try:
addr = ipaddress.IPv6Address(domain_literal[5:])
except ValueError as e:
raise EmailSyntaxError(f"The IPv6 address in brackets after the @-sign is not valid ({e}).") from e
# Return the IPv6Address object and construct a normalized
# domain literal.
return {
"domain_address": addr,
"domain": f"[IPv6:{addr.compressed}]",
}
# Nothing else is valid.
if ":" not in domain_literal:
raise EmailSyntaxError("The part after the @-sign in brackets is not an IPv4 address and has no address literal tag.")
# The tag (the part before the colon) has character restrictions,
# but since it must come from a registry of tags (in which only "IPv6" is defined),
# there's no need to check the syntax of the tag. See RFC 5321 4.1.2.
# Check for permitted ASCII characters. This actually doesn't matter
# since there will be an exception after anyway.
bad_chars = {
safe_character_display(c)
for c in domain_literal
if not DOMAIN_LITERAL_CHARS.match(c)
}
if bad_chars:
raise EmailSyntaxError("The part after the @-sign contains invalid characters in brackets: " + ", ".join(sorted(bad_chars)) + ".")
# There are no other domain literal tags.
# https://www.iana.org/assignments/address-literal-tags/address-literal-tags.xhtml
raise EmailSyntaxError("The part after the @-sign contains an invalid address literal tag in brackets.")