Source code for linkcheck.checker.mailtourl

# Copyright (C) 2000-2014 Bastian Kleineidam
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
Handler for mailto: links.
"""

import re
import urllib.parse
from email._parseaddr import AddressList

from . import urlbase
from .. import log, LOG_CHECK, strformat, url as urlutil
from dns import resolver
from ..network import iputil
from .const import WARN_MAIL_NO_MX_HOST


[docs]def getaddresses(addr): """Return list of email addresses from given field value.""" parsed = [mail for name, mail in AddressList(addr).addresslist if mail] if parsed: addresses = parsed elif addr: # we could not parse any mail addresses, so try with the raw string addresses = [addr] else: addresses = [] return addresses
[docs]def is_quoted(addr): """Return True iff mail address string is quoted.""" return addr.startswith('"') and addr.endswith('"')
[docs]def is_literal(domain): """Return True iff domain string is a literal.""" return domain.startswith('[') and domain.endswith(']')
_remove_quoted = re.compile(r'\\.').sub _quotes = re.compile(r'["\\]')
[docs]def is_missing_quote(addr): """Return True iff mail address is not correctly quoted.""" return _quotes.match(_remove_quoted("", addr[1:-1]))
# list of CGI keys to search for email addresses EMAIL_CGI_ADDRESS = ("to", "cc", "bcc") EMAIL_CGI_SUBJECT = "subject"
[docs]class MailtoUrl(urlbase.UrlBase): """ Url link with mailto scheme. """
[docs] def build_url(self): """Call super.build_url(), extract list of mail addresses from URL, and check their syntax. """ super().build_url() self.addresses = set() self.subject = None self.parse_addresses() if self.addresses: for addr in sorted(self.addresses): self.check_email_syntax(addr) if not self.valid: break elif not self.subject: self.add_warning( _("No mail addresses or email subject found in `%(url)s'.") % {"url": self.url} )
[docs] def parse_addresses(self): """Parse all mail addresses out of the URL target. Also parses optional CGI headers like "?to=foo@example.org". Stores parsed addresses in the self.addresses set. """ # cut off leading mailto: and unquote url = urllib.parse.unquote(self.base_url[7:], self.encoding) # search for cc, bcc, to and store in headers mode = 0 # 0=default, 1=quote, 2=esc quote = None i = 0 for i, c in enumerate(url): if mode == 0: if c == '?': break elif c in '<"': quote = c mode = 1 elif c == '\\': mode = 2 elif mode == 1: if c == '"' and quote == '"': mode = 0 elif c == '>' and quote == '<': mode = 0 elif mode == 2: mode = 0 if i < (len(url) - 1): self.addresses.update(getaddresses(url[:i])) try: headers = urllib.parse.parse_qs(url[(i + 1):], strict_parsing=True) for key, vals in headers.items(): if key.lower() in EMAIL_CGI_ADDRESS: # Only the first header value is added self.addresses.update( getaddresses(urllib.parse.unquote(vals[0], self.encoding)) ) if key.lower() == EMAIL_CGI_SUBJECT: self.subject = vals[0] except ValueError as err: self.add_warning(_("Error parsing CGI values: %s") % str(err)) else: self.addresses.update(getaddresses(url)) log.debug(LOG_CHECK, "addresses: %s", self.addresses)
[docs] def check_email_syntax(self, mail): """Check email syntax. The relevant RFCs: - How to check names (memo): https://tools.ietf.org/html/rfc3696 - Email address syntax https://tools.ietf.org/html/rfc2822 - SMTP protocol https://tools.ietf.org/html/rfc5321#section-4.1.3 - IPv6 https://tools.ietf.org/html/rfc4291#section-2.2 - Host syntax https://tools.ietf.org/html/rfc1123#section-2 """ # length checks # restrict email length to 256 characters # https://www.rfc-editor.org/errata_search.php?eid=1003 if len(mail) > 256: self.set_result( _( "Mail address `%(addr)s' too long. Allowed 256 chars," " was %(length)d chars." ) % {"addr": mail, "length": len(mail)}, valid=False, overwrite=False, ) return if "@" not in mail: self.set_result( _("Missing `@' in mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return # note: be sure to use rsplit since "@" can occur in local part local, domain = mail.rsplit("@", 1) if not local: self.set_result( _("Missing local part of mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return if not domain: self.set_result( _("Missing domain part of mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return if len(local) > 64: self.set_result( _( "Local part of mail address `%(addr)s' too long." " Allowed 64 chars, was %(length)d chars." ) % {"addr": mail, "length": len(local)}, valid=False, overwrite=False, ) return if len(domain) > 255: self.set_result( _( "Domain part of mail address `%(addr)s' too long." " Allowed 255 chars, was %(length)d chars." ) % {"addr": mail, "length": len(local)}, valid=False, overwrite=False, ) return # local part syntax check # Rules taken from https://tools.ietf.org/html/rfc3696#section-3 if is_quoted(local): if is_missing_quote(local): self.set_result( _("Unquoted double quote or backslash in mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return else: if local.startswith("."): self.set_result( _("Local part of mail address `%(addr)s' may not start with a dot.") % {"addr": mail}, valid=False, overwrite=False, ) return if local.endswith("."): self.set_result( _("Local part of mail address `%(addr)s' may not end with a dot.") % {"addr": mail}, valid=False, overwrite=False, ) return if ".." in local: self.set_result( _("Local part of mail address `%(addr)s' may not contain two dots.") % {"addr": mail}, valid=False, overwrite=False, ) return for char in '@ \\",[]': if char in local.replace(f"\\{char}", ""): self.set_result( _( "Local part of mail address `%(addr)s' contains" " unquoted character `%(char)s." ) % {"addr": mail, "char": char}, valid=False, overwrite=False, ) return # domain part syntax check if is_literal(domain): # it's an IP address ip = domain[1:-1] if ip.startswith("IPv6:"): ip = ip[5:] if not iputil.is_valid_ip(ip): self.set_result( _("Domain part of mail address `%(addr)s' has invalid IP.") % {"addr": mail}, valid=False, overwrite=False, ) return else: # it's a domain name if not urlutil.is_safe_domain(domain): self.set_result( _("Invalid domain part of mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return if domain.endswith(".") or domain.split(".")[-1].isdigit(): self.set_result( _("Invalid top level domain part of mail address `%(addr)s'.") % {"addr": mail}, valid=False, overwrite=False, ) return
[docs] def check_connection(self): """ Verify a list of email addresses. If one address fails, the whole list will fail. For each mail address the MX DNS records are found. If no MX records are found, print a warning and try to look for A DNS records. If no A records are found either print an error. """ for mail in sorted(self.addresses): self.check_smtp_domain(mail) if not self.valid: break
[docs] def check_smtp_domain(self, mail): """ Check a single mail address. """ from dns.exception import DNSException log.debug(LOG_CHECK, "checking mail address %r", mail) mail = strformat.ascii_safe(mail) username, domain = mail.rsplit('@', 1) log.debug(LOG_CHECK, "looking up MX mailhost %r", domain) try: answers = resolver.resolve(domain, 'MX', search=True) except DNSException: answers = [] if len(answers) == 0: self.add_warning( _("No MX mail host for %(domain)s found.") % {'domain': domain}, tag=WARN_MAIL_NO_MX_HOST, ) try: answers = resolver.resolve(domain, 'A', search=True) except DNSException: answers = [] if len(answers) == 0: self.set_result( _("No host for %(domain)s found.") % {'domain': domain}, valid=False, overwrite=True, ) return # set preference to zero mxdata = [(0, rdata.to_text(omit_final_dot=True)) for rdata in answers] else: from dns.rdtypes.mxbase import MXBase mxdata = [ (rdata.preference, rdata.exchange.to_text(omit_final_dot=True)) for rdata in answers if isinstance(rdata, MXBase) ] if not mxdata: self.set_result( _("Got invalid DNS answer %(answer)s for %(domain)s.") % {'answer': answers, 'domain': domain}, valid=False, overwrite=True, ) return # sort according to preference (lower preference means this # host should be preferred) mxdata.sort() # debug output log.debug(LOG_CHECK, "found %d MX mailhosts:", len(answers)) for preference, host in mxdata: log.debug(LOG_CHECK, "MX host %r, preference %d", host, preference) self.set_result(_("Valid mail address syntax"))
[docs] def set_cache_url(self): """ The cache url is a comma separated list of emails. """ emails = ",".join(sorted(self.addresses)) self.cache_url = f"{self.scheme}:{emails}"
[docs] def can_get_content(self): """ mailto: URLs do not have any content @return: False @rtype: bool """ return False