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| # These constants are defined by the email specifications. | |
| import re | |
| # Based on RFC 5322 3.2.3, these characters are permitted in email | |
| # addresses (not taking into account internationalization) separated by dots: | |
| ATEXT = r'a-zA-Z0-9_!#\$%&\'\*\+\-/=\?\^`\{\|\}~' | |
| ATEXT_RE = re.compile('[.' + ATEXT + ']') # ATEXT plus dots | |
| DOT_ATOM_TEXT = re.compile('[' + ATEXT + ']+(?:\\.[' + ATEXT + r']+)*\Z') | |
| # RFC 6531 3.3 extends the allowed characters in internationalized | |
| # addresses to also include three specific ranges of UTF8 defined in | |
| # RFC 3629 section 4, which appear to be the Unicode code points from | |
| # U+0080 to U+10FFFF. | |
| ATEXT_INTL = ATEXT + "\u0080-\U0010FFFF" | |
| ATEXT_INTL_DOT_RE = re.compile('[.' + ATEXT_INTL + ']') # ATEXT_INTL plus dots | |
| DOT_ATOM_TEXT_INTL = re.compile('[' + ATEXT_INTL + ']+(?:\\.[' + ATEXT_INTL + r']+)*\Z') | |
| # The domain part of the email address, after IDNA (ASCII) encoding, | |
| # must also satisfy the requirements of RFC 952/RFC 1123 2.1 which | |
| # restrict the allowed characters of hostnames further. | |
| ATEXT_HOSTNAME_INTL = re.compile(r"[a-zA-Z0-9\-\." + "\u0080-\U0010FFFF" + "]") | |
| HOSTNAME_LABEL = r'(?:(?:[a-zA-Z0-9][a-zA-Z0-9\-]*)?[a-zA-Z0-9])' | |
| DOT_ATOM_TEXT_HOSTNAME = re.compile(HOSTNAME_LABEL + r'(?:\.' + HOSTNAME_LABEL + r')*\Z') | |
| DOMAIN_NAME_REGEX = re.compile(r"[A-Za-z]\Z") # all TLDs currently end with a letter | |
| # Domain literal (RFC 5322 3.4.1) | |
| DOMAIN_LITERAL_CHARS = re.compile(r"[\u0021-\u00FA\u005E-\u007E]") | |
| # Quoted-string local part (RFC 5321 4.1.2, internationalized by RFC 6531 3.3) | |
| # The permitted characters in a quoted string are the characters in the range | |
| # 32-126, except that quotes and (literal) backslashes can only appear when escaped | |
| # by a backslash. When internationalized, UTF-8 strings are also permitted except | |
| # the ASCII characters that are not previously permitted (see above). | |
| # QUOTED_LOCAL_PART_ADDR = re.compile(r"^\"((?:[\u0020-\u0021\u0023-\u005B\u005D-\u007E]|\\[\u0020-\u007E])*)\"@(.*)") | |
| QTEXT_INTL = re.compile(r"[\u0020-\u007E\u0080-\U0010FFFF]") | |
| # Length constants | |
| # RFC 3696 + errata 1003 + errata 1690 (https://www.rfc-editor.org/errata_search.php?rfc=3696&eid=1690) | |
| # explains the maximum length of an email address is 254 octets. | |
| EMAIL_MAX_LENGTH = 254 | |
| LOCAL_PART_MAX_LENGTH = 64 | |
| DNS_LABEL_LENGTH_LIMIT = 63 # in "octets", RFC 1035 2.3.1 | |
| DOMAIN_MAX_LENGTH = 253 # in "octets" as transmitted, RFC 1035 2.3.4 and RFC 5321 4.5.3.1.2, and see https://stackoverflow.com/questions/32290167/what-is-the-maximum-length-of-a-dns-name | |
| # RFC 2142 | |
| CASE_INSENSITIVE_MAILBOX_NAMES = [ | |
| 'info', 'marketing', 'sales', 'support', # section 3 | |
| 'abuse', 'noc', 'security', # section 4 | |
| 'postmaster', 'hostmaster', 'usenet', 'news', 'webmaster', 'www', 'uucp', 'ftp', # section 5 | |
| ] | |