762 lines
35 KiB
Python
762 lines
35 KiB
Python
from .exceptions_types import EmailSyntaxError, ValidatedEmail
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from .rfc_constants import EMAIL_MAX_LENGTH, LOCAL_PART_MAX_LENGTH, DOMAIN_MAX_LENGTH, \
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DOT_ATOM_TEXT, DOT_ATOM_TEXT_INTL, ATEXT_RE, ATEXT_INTL_DOT_RE, ATEXT_HOSTNAME_INTL, QTEXT_INTL, \
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DNS_LABEL_LENGTH_LIMIT, DOT_ATOM_TEXT_HOSTNAME, DOMAIN_NAME_REGEX, DOMAIN_LITERAL_CHARS
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import re
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import unicodedata
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import idna # implements IDNA 2008; Python's codec is only IDNA 2003
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import ipaddress
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from typing import Optional, Tuple, TypedDict, Union
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def split_email(email: str) -> Tuple[Optional[str], str, str, bool]:
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# Return the display name, unescaped local part, and domain part
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# of the address, and whether the local part was quoted. If no
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# display name was present and angle brackets do not surround
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# the address, display name will be None; otherwise, it will be
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# set to the display name or the empty string if there were
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# angle brackets but no display name.
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# Typical email addresses have a single @-sign and no quote
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# characters, but the awkward "quoted string" local part form
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# (RFC 5321 4.1.2) allows @-signs and escaped quotes to appear
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# in the local part if the local part is quoted.
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# A `display name <addr>` format is also present in MIME messages
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# (RFC 5322 3.4) and this format is also often recognized in
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# mail UIs. It's not allowed in SMTP commands or in typical web
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# login forms, but parsing it has been requested, so it's done
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# here as a convenience. It's implemented in the spirit but not
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# the letter of RFC 5322 3.4 because MIME messages allow newlines
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# and comments as a part of the CFWS rule, but this is typically
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# not allowed in mail UIs (although comment syntax was requested
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# once too).
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#
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# Display names are either basic characters (the same basic characters
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# permitted in email addresses, but periods are not allowed and spaces
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# are allowed; see RFC 5322 Appendix A.1.2), or or a quoted string with
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# the same rules as a quoted local part. (Multiple quoted strings might
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# be allowed? Unclear.) Optional space (RFC 5322 3.4 CFWS) and then the
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# email address follows in angle brackets.
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#
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# An initial quote is ambiguous between starting a display name or
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# a quoted local part --- fun.
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#
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# We assume the input string is already stripped of leading and
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# trailing CFWS.
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def split_string_at_unquoted_special(text: str, specials: Tuple[str, ...]) -> Tuple[str, str]:
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# Split the string at the first character in specials (an @-sign
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# or left angle bracket) that does not occur within quotes and
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# is not followed by a Unicode combining character.
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# If no special character is found, raise an error.
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inside_quote = False
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escaped = False
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left_part = ""
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for i, c in enumerate(text):
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# < plus U+0338 (Combining Long Solidus Overlay) normalizes to
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# ≮ U+226E (Not Less-Than), and it would be confusing to treat
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# the < as the start of "<email>" syntax in that case. Liekwise,
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# if anything combines with an @ or ", we should probably not
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# treat it as a special character.
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if unicodedata.normalize("NFC", text[i:])[0] != c:
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left_part += c
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elif inside_quote:
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left_part += c
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if c == '\\' and not escaped:
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escaped = True
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elif c == '"' and not escaped:
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# The only way to exit the quote is an unescaped quote.
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inside_quote = False
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escaped = False
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else:
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escaped = False
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elif c == '"':
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left_part += c
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inside_quote = True
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elif c in specials:
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# When unquoted, stop before a special character.
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break
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else:
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left_part += c
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if len(left_part) == len(text):
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raise EmailSyntaxError("An email address must have an @-sign.")
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# The right part is whatever is left.
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right_part = text[len(left_part):]
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return left_part, right_part
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def unquote_quoted_string(text: str) -> Tuple[str, bool]:
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# Remove surrounding quotes and unescape escaped backslashes
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# and quotes. Escapes are parsed liberally. I think only
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# backslashes and quotes can be escaped but we'll allow anything
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# to be.
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quoted = False
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escaped = False
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value = ""
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for i, c in enumerate(text):
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if quoted:
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if escaped:
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value += c
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escaped = False
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elif c == '\\':
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escaped = True
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elif c == '"':
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if i != len(text) - 1:
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raise EmailSyntaxError("Extra character(s) found after close quote: "
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+ ", ".join(safe_character_display(c) for c in text[i + 1:]))
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break
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else:
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value += c
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elif i == 0 and c == '"':
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quoted = True
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else:
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value += c
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return value, quoted
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# Split the string at the first unquoted @-sign or left angle bracket.
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left_part, right_part = split_string_at_unquoted_special(email, ("@", "<"))
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# If the right part starts with an angle bracket,
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# then the left part is a display name and the rest
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# of the right part up to the final right angle bracket
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# is the email address, .
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if right_part.startswith("<"):
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# Remove space between the display name and angle bracket.
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left_part = left_part.rstrip()
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# Unquote and unescape the display name.
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display_name, display_name_quoted = unquote_quoted_string(left_part)
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# Check that only basic characters are present in a
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# non-quoted display name.
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if not display_name_quoted:
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bad_chars = {
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safe_character_display(c)
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for c in display_name
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if (not ATEXT_RE.match(c) and c != ' ') or c == '.'
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}
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if bad_chars:
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raise EmailSyntaxError("The display name contains invalid characters when not quoted: " + ", ".join(sorted(bad_chars)) + ".")
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# Check for other unsafe characters.
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check_unsafe_chars(display_name, allow_space=True)
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# Check that the right part ends with an angle bracket
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# but allow spaces after it, I guess.
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if ">" not in right_part:
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raise EmailSyntaxError("An open angle bracket at the start of the email address has to be followed by a close angle bracket at the end.")
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right_part = right_part.rstrip(" ")
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if right_part[-1] != ">":
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raise EmailSyntaxError("There can't be anything after the email address.")
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# Remove the initial and trailing angle brackets.
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addr_spec = right_part[1:].rstrip(">")
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# Split the email address at the first unquoted @-sign.
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local_part, domain_part = split_string_at_unquoted_special(addr_spec, ("@",))
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# Otherwise there is no display name. The left part is the local
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# part and the right part is the domain.
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else:
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display_name = None
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local_part, domain_part = left_part, right_part
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if domain_part.startswith("@"):
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domain_part = domain_part[1:]
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# Unquote the local part if it is quoted.
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local_part, is_quoted_local_part = unquote_quoted_string(local_part)
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return display_name, local_part, domain_part, is_quoted_local_part
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def get_length_reason(addr: str, limit: int) -> str:
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"""Helper function to return an error message related to invalid length."""
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diff = len(addr) - limit
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suffix = "s" if diff > 1 else ""
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return f"({diff} character{suffix} too many)"
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def safe_character_display(c: str) -> str:
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# Return safely displayable characters in quotes.
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if c == '\\':
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return f"\"{c}\"" # can't use repr because it escapes it
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if unicodedata.category(c)[0] in ("L", "N", "P", "S"):
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return repr(c)
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# Construct a hex string in case the unicode name doesn't exist.
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if ord(c) < 0xFFFF:
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h = f"U+{ord(c):04x}".upper()
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else:
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h = f"U+{ord(c):08x}".upper()
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# Return the character name or, if it has no name, the hex string.
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return unicodedata.name(c, h)
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class LocalPartValidationResult(TypedDict):
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local_part: str
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ascii_local_part: Optional[str]
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smtputf8: bool
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def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_empty_local: bool = False,
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quoted_local_part: bool = False) -> LocalPartValidationResult:
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"""Validates the syntax of the local part of an email address."""
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if len(local) == 0:
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if not allow_empty_local:
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raise EmailSyntaxError("There must be something before the @-sign.")
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# The caller allows an empty local part. Useful for validating certain
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# Postfix aliases.
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return {
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"local_part": local,
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"ascii_local_part": local,
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"smtputf8": False,
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}
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# Check the length of the local part by counting characters.
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# (RFC 5321 4.5.3.1.1)
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# We're checking the number of characters here. If the local part
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# is ASCII-only, then that's the same as bytes (octets). If it's
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# internationalized, then the UTF-8 encoding may be longer, but
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# that may not be relevant. We will check the total address length
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# instead.
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if len(local) > LOCAL_PART_MAX_LENGTH:
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reason = get_length_reason(local, limit=LOCAL_PART_MAX_LENGTH)
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raise EmailSyntaxError(f"The email address is too long before the @-sign {reason}.")
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# Check the local part against the non-internationalized regular expression.
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# Most email addresses match this regex so it's probably fastest to check this first.
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# (RFC 5322 3.2.3)
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# All local parts matching the dot-atom rule are also valid as a quoted string
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# so if it was originally quoted (quoted_local_part is True) and this regex matches,
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# it's ok.
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# (RFC 5321 4.1.2 / RFC 5322 3.2.4).
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if DOT_ATOM_TEXT.match(local):
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# It's valid. And since it's just the permitted ASCII characters,
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# it's normalized and safe. If the local part was originally quoted,
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# the quoting was unnecessary and it'll be returned as normalized to
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# non-quoted form.
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# Return the local part and flag that SMTPUTF8 is not needed.
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return {
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"local_part": local,
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"ascii_local_part": local,
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"smtputf8": False,
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}
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# The local part failed the basic dot-atom check. Try the extended character set
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# for internationalized addresses. It's the same pattern but with additional
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# characters permitted.
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# RFC 6531 section 3.3.
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valid: Optional[str] = None
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requires_smtputf8 = False
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if DOT_ATOM_TEXT_INTL.match(local):
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# But international characters in the local part may not be permitted.
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if not allow_smtputf8:
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# Check for invalid characters against the non-internationalized
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# permitted character set.
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# (RFC 5322 3.2.3)
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bad_chars = {
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safe_character_display(c)
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for c in local
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if not ATEXT_RE.match(c)
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}
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if bad_chars:
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raise EmailSyntaxError("Internationalized characters before the @-sign are not supported: " + ", ".join(sorted(bad_chars)) + ".")
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# Although the check above should always find something, fall back to this just in case.
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raise EmailSyntaxError("Internationalized characters before the @-sign are not supported.")
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# It's valid.
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valid = "dot-atom"
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requires_smtputf8 = True
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# There are no syntactic restrictions on quoted local parts, so if
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# it was originally quoted, it is probably valid. More characters
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# are allowed, like @-signs, spaces, and quotes, and there are no
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# restrictions on the placement of dots, as in dot-atom local parts.
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elif quoted_local_part:
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# Check for invalid characters in a quoted string local part.
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# (RFC 5321 4.1.2. RFC 5322 lists additional permitted *obsolete*
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# characters which are *not* allowed here. RFC 6531 section 3.3
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# extends the range to UTF8 strings.)
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bad_chars = {
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safe_character_display(c)
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for c in local
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if not QTEXT_INTL.match(c)
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}
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if bad_chars:
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raise EmailSyntaxError("The email address contains invalid characters in quotes before the @-sign: " + ", ".join(sorted(bad_chars)) + ".")
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# See if any characters are outside of the ASCII range.
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bad_chars = {
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safe_character_display(c)
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for c in local
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if not (32 <= ord(c) <= 126)
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}
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if bad_chars:
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requires_smtputf8 = True
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# International characters in the local part may not be permitted.
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if not allow_smtputf8:
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raise EmailSyntaxError("Internationalized characters before the @-sign are not supported: " + ", ".join(sorted(bad_chars)) + ".")
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# It's valid.
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valid = "quoted"
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# If the local part matches the internationalized dot-atom form or was quoted,
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# perform additional checks for Unicode strings.
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if valid:
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# Check that the local part is a valid, safe, and sensible Unicode string.
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# Some of this may be redundant with the range U+0080 to U+10FFFF that is checked
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# by DOT_ATOM_TEXT_INTL and QTEXT_INTL. Other characters may be permitted by the
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# email specs, but they may not be valid, safe, or sensible Unicode strings.
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# See the function for rationale.
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check_unsafe_chars(local, allow_space=(valid == "quoted"))
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# Try encoding to UTF-8. Failure is possible with some characters like
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# surrogate code points, but those are checked above. Still, we don't
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# want to have an unhandled exception later.
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try:
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local.encode("utf8")
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except ValueError as e:
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raise EmailSyntaxError("The email address contains an invalid character.") from e
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# If this address passes only by the quoted string form, re-quote it
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# and backslash-escape quotes and backslashes (removing any unnecessary
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# escapes). Per RFC 5321 4.1.2, "all quoted forms MUST be treated as equivalent,
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# and the sending system SHOULD transmit the form that uses the minimum quoting possible."
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if valid == "quoted":
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local = '"' + re.sub(r'(["\\])', r'\\\1', local) + '"'
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return {
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"local_part": local,
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"ascii_local_part": local if not requires_smtputf8 else None,
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"smtputf8": requires_smtputf8,
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}
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# It's not a valid local part. Let's find out why.
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# (Since quoted local parts are all valid or handled above, these checks
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# don't apply in those cases.)
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# Check for invalid characters.
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# (RFC 5322 3.2.3, plus RFC 6531 3.3)
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bad_chars = {
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safe_character_display(c)
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for c in local
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if not ATEXT_INTL_DOT_RE.match(c)
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}
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if bad_chars:
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raise EmailSyntaxError("The email address contains invalid characters before the @-sign: " + ", ".join(sorted(bad_chars)) + ".")
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# Check for dot errors imposted by the dot-atom rule.
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# (RFC 5322 3.2.3)
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check_dot_atom(local, 'An email address cannot start with a {}.', 'An email address cannot have a {} immediately before the @-sign.', is_hostname=False)
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# All of the reasons should already have been checked, but just in case
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# we have a fallback message.
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raise EmailSyntaxError("The email address contains invalid characters before the @-sign.")
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def check_unsafe_chars(s: str, allow_space: bool = False) -> None:
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# Check for unsafe characters or characters that would make the string
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# invalid or non-sensible Unicode.
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bad_chars = set()
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for i, c in enumerate(s):
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category = unicodedata.category(c)
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if category[0] in ("L", "N", "P", "S"):
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# Letters, numbers, punctuation, and symbols are permitted.
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pass
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elif category[0] == "M":
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# Combining character in first position would combine with something
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# outside of the email address if concatenated, so they are not safe.
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# We also check if this occurs after the @-sign, which would not be
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# sensible because it would modify the @-sign.
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if i == 0:
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bad_chars.add(c)
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elif category == "Zs":
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# Spaces outside of the ASCII range are not specifically disallowed in
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# internationalized addresses as far as I can tell, but they violate
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# the spirit of the non-internationalized specification that email
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# addresses do not contain ASCII spaces when not quoted. Excluding
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# ASCII spaces when not quoted is handled directly by the atom regex.
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#
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# In quoted-string local parts, spaces are explicitly permitted, and
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# the ASCII space has category Zs, so we must allow it here, and we'll
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# allow all Unicode spaces to be consistent.
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if not allow_space:
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bad_chars.add(c)
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elif category[0] == "Z":
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# The two line and paragraph separator characters (in categories Zl and Zp)
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# are not specifically disallowed in internationalized addresses
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# as far as I can tell, but they violate the spirit of the non-internationalized
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# specification that email addresses do not contain line breaks when not quoted.
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bad_chars.add(c)
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elif category[0] == "C":
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# Control, format, surrogate, private use, and unassigned code points (C)
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# are all unsafe in various ways. Control and format characters can affect
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# text rendering if the email address is concatenated with other text.
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# Bidirectional format characters are unsafe, even if used properly, because
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# they cause an email address to render as a different email address.
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# Private use characters do not make sense for publicly deliverable
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# email addresses.
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bad_chars.add(c)
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else:
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# All categories should be handled above, but in case there is something new
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# to the Unicode specification in the future, reject all other categories.
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bad_chars.add(c)
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if bad_chars:
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raise EmailSyntaxError("The email address contains unsafe characters: "
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+ ", ".join(safe_character_display(c) for c in sorted(bad_chars)) + ".")
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def check_dot_atom(label: str, start_descr: str, end_descr: str, is_hostname: bool) -> None:
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# RFC 5322 3.2.3
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if label.endswith("."):
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raise EmailSyntaxError(end_descr.format("period"))
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if label.startswith("."):
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raise EmailSyntaxError(start_descr.format("period"))
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if ".." in label:
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raise EmailSyntaxError("An email address cannot have two periods in a row.")
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if is_hostname:
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# RFC 952
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if label.endswith("-"):
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raise EmailSyntaxError(end_descr.format("hyphen"))
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if label.startswith("-"):
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raise EmailSyntaxError(start_descr.format("hyphen"))
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if ".-" in label or "-." in label:
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raise EmailSyntaxError("An email address cannot have a period and a hyphen next to each other.")
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class DomainNameValidationResult(TypedDict):
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ascii_domain: str
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domain: str
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def validate_email_domain_name(domain: str, test_environment: bool = False, globally_deliverable: bool = True) -> DomainNameValidationResult:
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"""Validates the syntax of the domain part of an email address."""
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# Check for invalid characters.
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# (RFC 952 plus RFC 6531 section 3.3 for internationalized addresses)
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bad_chars = {
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safe_character_display(c)
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for c in domain
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if not ATEXT_HOSTNAME_INTL.match(c)
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}
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if bad_chars:
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raise EmailSyntaxError("The part after the @-sign contains invalid characters: " + ", ".join(sorted(bad_chars)) + ".")
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# 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 and
|
|
# U+1FEF which normalizes to a backtick, which is not an allowed hostname character.
|
|
# Since several characters *are* normalized to a dot, this has to come before
|
|
# checks related to dots, like check_dot_atom which comes next.
|
|
original_domain = domain
|
|
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
|
|
|
|
# Check for invalid characters after Unicode normalization which are not caught
|
|
# by uts46_remap (see tests for examples).
|
|
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 after Unicode normalization: " + ", ".join(sorted(bad_chars)) + ".")
|
|
|
|
# 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.
|
|
#
|
|
# 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.
|
|
#
|
|
# idna.encode also checks the domain name length after encoding but it
|
|
# doesn't give a nice error, so we call the underlying idna.alabel method
|
|
# directly. idna.alabel checks label length and doesn't give great messages,
|
|
# but we can't easily go to lower level methods.
|
|
try:
|
|
ascii_domain = ".".join(
|
|
idna.alabel(label).decode("ascii")
|
|
for label in domain.split(".")
|
|
)
|
|
except idna.IDNAError as e:
|
|
# Some errors would have already been raised by idna.uts46_remap.
|
|
raise EmailSyntaxError(f"The part after the @-sign is invalid ({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:
|
|
if ascii_domain == original_domain:
|
|
reason = get_length_reason(ascii_domain, limit=DOMAIN_MAX_LENGTH)
|
|
raise EmailSyntaxError(f"The email address is too long after the @-sign {reason}.")
|
|
else:
|
|
diff = len(ascii_domain) - DOMAIN_MAX_LENGTH
|
|
s = "" if diff == 1 else "s"
|
|
raise EmailSyntaxError(f"The email address is too long after the @-sign ({diff} byte{s} too many after IDNA encoding).")
|
|
|
|
# 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,
|
|
# which we return to the caller as a part of the normalized email
|
|
# address.
|
|
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 that this normalized domain name has not somehow become
|
|
# an invalid domain name. All of the checks before this point
|
|
# using the idna package probably guarantee that we now have
|
|
# a valid international domain name in most respects. But it
|
|
# doesn't hurt to re-apply some tests to be sure. See the similar
|
|
# tests above.
|
|
|
|
# Check for invalid and unsafe characters. We have no test
|
|
# case for this.
|
|
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)
|
|
|
|
# Check that it can be encoded back to IDNA ASCII. We have no test
|
|
# case for this.
|
|
try:
|
|
idna.encode(domain_i18n)
|
|
except idna.IDNAError as e:
|
|
raise EmailSyntaxError(f"The part after the @-sign became invalid after normalizing to international characters ({e}).") from e
|
|
|
|
# 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: ValidatedEmail) -> None:
|
|
# There are three forms of the email address whose length must be checked:
|
|
#
|
|
# 1) The original email address string. Since callers may continue to use
|
|
# this string, even though we recommend using the normalized form, we
|
|
# should not pass validation when the original input is not valid. This
|
|
# form is checked first because it is the original input.
|
|
# 2) The normalized email address. We perform Unicode NFC normalization of
|
|
# the local part, we normalize the domain to internationalized characters
|
|
# (if originaly IDNA ASCII) which also includes Unicode normalization,
|
|
# and we may remove quotes in quoted local parts. We recommend that
|
|
# callers use this string, so it must be valid.
|
|
# 3) The email address with the IDNA ASCII representation of the domain
|
|
# name, since this string may be used with email stacks that don't
|
|
# support UTF-8. Since this is the least likely to be used by callers,
|
|
# it is checked last. Note that ascii_email will only be set if the
|
|
# local part is ASCII, but conceivably the caller may combine a
|
|
# internationalized local part with an ASCII domain, so we check this
|
|
# on that combination also. Since we only return the normalized local
|
|
# part, we use that (and not the unnormalized local part).
|
|
#
|
|
# In all cases, the length is checked in UTF-8 because the SMTPUTF8
|
|
# extension to SMTP validates the length in bytes.
|
|
|
|
addresses_to_check = [
|
|
(addrinfo.original, None),
|
|
(addrinfo.normalized, "after normalization"),
|
|
((addrinfo.ascii_local_part or addrinfo.local_part or "") + "@" + addrinfo.ascii_domain, "when the part after the @-sign is converted to IDNA ASCII"),
|
|
]
|
|
|
|
for addr, reason in addresses_to_check:
|
|
addr_len = len(addr)
|
|
addr_utf8_len = len(addr.encode("utf8"))
|
|
diff = addr_utf8_len - EMAIL_MAX_LENGTH
|
|
if diff > 0:
|
|
if reason is None and addr_len == addr_utf8_len:
|
|
# If there is no normalization or transcoding,
|
|
# we can give a simple count of the number of
|
|
# characters over the limit.
|
|
reason = get_length_reason(addr, limit=EMAIL_MAX_LENGTH)
|
|
elif reason is None:
|
|
# If there is no normalization but there is
|
|
# some transcoding to UTF-8, we can compute
|
|
# the minimum number of characters over the
|
|
# limit by dividing the number of bytes over
|
|
# the limit by the maximum number of bytes
|
|
# per character.
|
|
mbpc = max(len(c.encode("utf8")) for c in addr)
|
|
mchars = max(1, diff // mbpc)
|
|
suffix = "s" if diff > 1 else ""
|
|
if mchars == diff:
|
|
reason = f"({diff} character{suffix} too many)"
|
|
else:
|
|
reason = f"({mchars}-{diff} character{suffix} too many)"
|
|
else:
|
|
# Since there is normalization, the number of
|
|
# characters in the input that need to change is
|
|
# impossible to know.
|
|
suffix = "s" if diff > 1 else ""
|
|
reason += f" ({diff} byte{suffix} too many)"
|
|
raise EmailSyntaxError(f"The email address is too long {reason}.")
|
|
|
|
|
|
class DomainLiteralValidationResult(TypedDict):
|
|
domain_address: Union[ipaddress.IPv4Address, ipaddress.IPv6Address]
|
|
domain: str
|
|
|
|
|
|
def validate_email_domain_literal(domain_literal: str) -> DomainLiteralValidationResult:
|
|
# 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.
|
|
|
|
addr: Union[ipaddress.IPv4Address, ipaddress.IPv6Address]
|
|
|
|
# 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.")
|