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484 lines
18 KiB
484 lines
18 KiB
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Victor Stinner <vstinner@python.org>
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Date: Fri, 15 Dec 2023 16:10:40 +0100
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Subject: [PATCH] 00415: [CVE-2023-27043] gh-102988: Reject malformed addresses
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in email.parseaddr() (#111116)
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Detect email address parsing errors and return empty tuple to
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indicate the parsing error (old API). Add an optional 'strict'
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parameter to getaddresses() and parseaddr() functions. Patch by
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Thomas Dwyer.
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Co-Authored-By: Thomas Dwyer <github@tomd.tel>
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---
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Doc/library/email.utils.rst | 19 +-
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Lib/email/utils.py | 151 +++++++++++++-
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Lib/test/test_email/test_email.py | 187 +++++++++++++++++-
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...-10-20-15-28-08.gh-issue-102988.dStNO7.rst | 8 +
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4 files changed, 344 insertions(+), 21 deletions(-)
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create mode 100644 Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst
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diff --git a/Doc/library/email.utils.rst b/Doc/library/email.utils.rst
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index 6ba42491d6..6bd45200d8 100644
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--- a/Doc/library/email.utils.rst
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+++ b/Doc/library/email.utils.rst
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@@ -58,13 +58,18 @@ of the new API.
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begins with angle brackets, they are stripped off.
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-.. function:: parseaddr(address)
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+.. function:: parseaddr(address, *, strict=True)
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Parse address -- which should be the value of some address-containing field such
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as :mailheader:`To` or :mailheader:`Cc` -- into its constituent *realname* and
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*email address* parts. Returns a tuple of that information, unless the parse
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fails, in which case a 2-tuple of ``('', '')`` is returned.
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+ If *strict* is true, use a strict parser which rejects malformed inputs.
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+
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+ .. versionchanged:: 3.13
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+ Add *strict* optional parameter and reject malformed inputs by default.
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+
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.. function:: formataddr(pair, charset='utf-8')
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@@ -82,12 +87,15 @@ of the new API.
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Added the *charset* option.
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-.. function:: getaddresses(fieldvalues)
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+.. function:: getaddresses(fieldvalues, *, strict=True)
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This method returns a list of 2-tuples of the form returned by ``parseaddr()``.
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*fieldvalues* is a sequence of header field values as might be returned by
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- :meth:`Message.get_all <email.message.Message.get_all>`. Here's a simple
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- example that gets all the recipients of a message::
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+ :meth:`Message.get_all <email.message.Message.get_all>`.
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+
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+ If *strict* is true, use a strict parser which rejects malformed inputs.
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+
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+ Here's a simple example that gets all the recipients of a message::
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from email.utils import getaddresses
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@@ -97,6 +105,9 @@ of the new API.
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resent_ccs = msg.get_all('resent-cc', [])
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all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)
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+ .. versionchanged:: 3.13
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+ Add *strict* optional parameter and reject malformed inputs by default.
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+
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.. function:: parsedate(date)
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diff --git a/Lib/email/utils.py b/Lib/email/utils.py
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index 1de547a011..e53abc8b84 100644
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--- a/Lib/email/utils.py
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+++ b/Lib/email/utils.py
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@@ -48,6 +48,7 @@
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specialsre = re.compile(r'[][\\()<>@,:;".]')
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escapesre = re.compile(r'[\\"]')
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+
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def _has_surrogates(s):
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"""Return True if s may contain surrogate-escaped binary data."""
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# This check is based on the fact that unless there are surrogates, utf8
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@@ -106,12 +107,127 @@ def formataddr(pair, charset='utf-8'):
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return address
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+def _iter_escaped_chars(addr):
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+ pos = 0
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+ escape = False
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+ for pos, ch in enumerate(addr):
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+ if escape:
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+ yield (pos, '\\' + ch)
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+ escape = False
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+ elif ch == '\\':
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+ escape = True
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+ else:
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+ yield (pos, ch)
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+ if escape:
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+ yield (pos, '\\')
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-def getaddresses(fieldvalues):
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- """Return a list of (REALNAME, EMAIL) for each fieldvalue."""
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- all = COMMASPACE.join(str(v) for v in fieldvalues)
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- a = _AddressList(all)
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- return a.addresslist
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+
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+def _strip_quoted_realnames(addr):
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+ """Strip real names between quotes."""
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+ if '"' not in addr:
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+ # Fast path
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+ return addr
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+
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+ start = 0
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+ open_pos = None
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+ result = []
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+ for pos, ch in _iter_escaped_chars(addr):
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+ if ch == '"':
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+ if open_pos is None:
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+ open_pos = pos
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+ else:
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+ if start != open_pos:
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+ result.append(addr[start:open_pos])
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+ start = pos + 1
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+ open_pos = None
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+
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+ if start < len(addr):
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+ result.append(addr[start:])
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+
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+ return ''.join(result)
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+
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+
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+supports_strict_parsing = True
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+
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+def getaddresses(fieldvalues, *, strict=True):
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+ """Return a list of (REALNAME, EMAIL) or ('','') for each fieldvalue.
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+
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+ When parsing fails for a fieldvalue, a 2-tuple of ('', '') is returned in
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+ its place.
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+
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+ If strict is true, use a strict parser which rejects malformed inputs.
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+ """
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+
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+ # If strict is true, if the resulting list of parsed addresses is greater
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+ # than the number of fieldvalues in the input list, a parsing error has
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+ # occurred and consequently a list containing a single empty 2-tuple [('',
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+ # '')] is returned in its place. This is done to avoid invalid output.
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+ #
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+ # Malformed input: getaddresses(['alice@example.com <bob@example.com>'])
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+ # Invalid output: [('', 'alice@example.com'), ('', 'bob@example.com')]
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+ # Safe output: [('', '')]
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+
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+ if not strict:
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+ all = COMMASPACE.join(str(v) for v in fieldvalues)
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+ a = _AddressList(all)
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+ return a.addresslist
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+
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+ fieldvalues = [str(v) for v in fieldvalues]
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+ fieldvalues = _pre_parse_validation(fieldvalues)
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+ addr = COMMASPACE.join(fieldvalues)
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+ a = _AddressList(addr)
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+ result = _post_parse_validation(a.addresslist)
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+
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+ # Treat output as invalid if the number of addresses is not equal to the
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+ # expected number of addresses.
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+ n = 0
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+ for v in fieldvalues:
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+ # When a comma is used in the Real Name part it is not a deliminator.
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+ # So strip those out before counting the commas.
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+ v = _strip_quoted_realnames(v)
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+ # Expected number of addresses: 1 + number of commas
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+ n += 1 + v.count(',')
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+ if len(result) != n:
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+ return [('', '')]
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+
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+ return result
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+
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+
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+def _check_parenthesis(addr):
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+ # Ignore parenthesis in quoted real names.
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+ addr = _strip_quoted_realnames(addr)
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+
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+ opens = 0
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+ for pos, ch in _iter_escaped_chars(addr):
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+ if ch == '(':
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+ opens += 1
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+ elif ch == ')':
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+ opens -= 1
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+ if opens < 0:
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+ return False
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+ return (opens == 0)
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+
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+
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+def _pre_parse_validation(email_header_fields):
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+ accepted_values = []
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+ for v in email_header_fields:
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+ if not _check_parenthesis(v):
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+ v = "('', '')"
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+ accepted_values.append(v)
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+
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+ return accepted_values
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+
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+
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+def _post_parse_validation(parsed_email_header_tuples):
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+ accepted_values = []
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+ # The parser would have parsed a correctly formatted domain-literal
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+ # The existence of an [ after parsing indicates a parsing failure
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+ for v in parsed_email_header_tuples:
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+ if '[' in v[1]:
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+ v = ('', '')
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+ accepted_values.append(v)
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+
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+ return accepted_values
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def _format_timetuple_and_zone(timetuple, zone):
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@@ -205,16 +321,33 @@ def parsedate_to_datetime(data):
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tzinfo=datetime.timezone(datetime.timedelta(seconds=tz)))
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-def parseaddr(addr):
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+def parseaddr(addr, *, strict=True):
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"""
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Parse addr into its constituent realname and email address parts.
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Return a tuple of realname and email address, unless the parse fails, in
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which case return a 2-tuple of ('', '').
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+
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+ If strict is True, use a strict parser which rejects malformed inputs.
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"""
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- addrs = _AddressList(addr).addresslist
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- if not addrs:
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- return '', ''
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+ if not strict:
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+ addrs = _AddressList(addr).addresslist
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+ if not addrs:
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+ return ('', '')
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+ return addrs[0]
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+
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+ if isinstance(addr, list):
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+ addr = addr[0]
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+
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+ if not isinstance(addr, str):
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+ return ('', '')
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+
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+ addr = _pre_parse_validation([addr])[0]
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+ addrs = _post_parse_validation(_AddressList(addr).addresslist)
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+
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+ if not addrs or len(addrs) > 1:
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+ return ('', '')
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+
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return addrs[0]
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diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
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index a373c53c7c..c616398eb1 100644
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--- a/Lib/test/test_email/test_email.py
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+++ b/Lib/test/test_email/test_email.py
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@@ -16,6 +16,7 @@
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import email
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import email.policy
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+import email.utils
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from email.charset import Charset
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from email.generator import Generator, DecodedGenerator, BytesGenerator
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@@ -3352,15 +3353,137 @@ def test_getaddresses_comma_in_name(self):
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],
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)
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+ def test_parsing_errors(self):
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+ """Test for parsing errors from CVE-2023-27043 and CVE-2019-16056"""
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+ alice = 'alice@example.org'
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+ bob = 'bob@example.com'
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+ empty = ('', '')
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+
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+ # Test utils.getaddresses() and utils.parseaddr() on malformed email
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+ # addresses: default behavior (strict=True) rejects malformed address,
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+ # and strict=False which tolerates malformed address.
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+ for invalid_separator, expected_non_strict in (
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+ ('(', [(f'<{bob}>', alice)]),
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+ (')', [('', alice), empty, ('', bob)]),
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+ ('<', [('', alice), empty, ('', bob), empty]),
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+ ('>', [('', alice), empty, ('', bob)]),
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+ ('[', [('', f'{alice}[<{bob}>]')]),
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+ (']', [('', alice), empty, ('', bob)]),
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+ ('@', [empty, empty, ('', bob)]),
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+ (';', [('', alice), empty, ('', bob)]),
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+ (':', [('', alice), ('', bob)]),
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+ ('.', [('', alice + '.'), ('', bob)]),
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+ ('"', [('', alice), ('', f'<{bob}>')]),
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+ ):
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+ address = f'{alice}{invalid_separator}<{bob}>'
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+ with self.subTest(address=address):
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+ self.assertEqual(utils.getaddresses([address]),
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+ [empty])
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+ self.assertEqual(utils.getaddresses([address], strict=False),
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+ expected_non_strict)
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+
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+ self.assertEqual(utils.parseaddr([address]),
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+ empty)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Comma (',') is treated differently depending on strict parameter.
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+ # Comma without quotes.
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+ address = f'{alice},<{bob}>'
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+ self.assertEqual(utils.getaddresses([address]),
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+ [('', alice), ('', bob)])
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+ self.assertEqual(utils.getaddresses([address], strict=False),
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+ [('', alice), ('', bob)])
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+ self.assertEqual(utils.parseaddr([address]),
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+ empty)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Real name between quotes containing comma.
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+ address = '"Alice, alice@example.org" <bob@example.com>'
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+ expected_strict = ('Alice, alice@example.org', 'bob@example.com')
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+ self.assertEqual(utils.getaddresses([address]), [expected_strict])
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+ self.assertEqual(utils.getaddresses([address], strict=False), [expected_strict])
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+ self.assertEqual(utils.parseaddr([address]), expected_strict)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Valid parenthesis in comments.
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+ address = 'alice@example.org (Alice)'
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+ expected_strict = ('Alice', 'alice@example.org')
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+ self.assertEqual(utils.getaddresses([address]), [expected_strict])
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+ self.assertEqual(utils.getaddresses([address], strict=False), [expected_strict])
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+ self.assertEqual(utils.parseaddr([address]), expected_strict)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Invalid parenthesis in comments.
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+ address = 'alice@example.org )Alice('
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+ self.assertEqual(utils.getaddresses([address]), [empty])
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+ self.assertEqual(utils.getaddresses([address], strict=False),
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+ [('', 'alice@example.org'), ('', ''), ('', 'Alice')])
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+ self.assertEqual(utils.parseaddr([address]), empty)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Two addresses with quotes separated by comma.
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+ address = '"Jane Doe" <jane@example.net>, "John Doe" <john@example.net>'
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+ self.assertEqual(utils.getaddresses([address]),
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+ [('Jane Doe', 'jane@example.net'),
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+ ('John Doe', 'john@example.net')])
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+ self.assertEqual(utils.getaddresses([address], strict=False),
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+ [('Jane Doe', 'jane@example.net'),
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+ ('John Doe', 'john@example.net')])
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+ self.assertEqual(utils.parseaddr([address]), empty)
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+ self.assertEqual(utils.parseaddr([address], strict=False),
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+ ('', address))
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+
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+ # Test email.utils.supports_strict_parsing attribute
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+ self.assertEqual(email.utils.supports_strict_parsing, True)
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+
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def test_getaddresses_nasty(self):
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- eq = self.assertEqual
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- eq(utils.getaddresses(['foo: ;']), [('', '')])
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- eq(utils.getaddresses(
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- ['[]*-- =~$']),
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- [('', ''), ('', ''), ('', '*--')])
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- eq(utils.getaddresses(
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- ['foo: ;', '"Jason R. Mastaler" <jason@dom.ain>']),
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- [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')])
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+ for addresses, expected in (
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+ (['"Sürname, Firstname" <to@example.com>'],
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+ [('Sürname, Firstname', 'to@example.com')]),
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+
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+ (['foo: ;'],
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+ [('', '')]),
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+
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+ (['foo: ;', '"Jason R. Mastaler" <jason@dom.ain>'],
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+ [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')]),
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+
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+ ([r'Pete(A nice \) chap) <pete(his account)@silly.test(his host)>'],
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+ [('Pete (A nice ) chap his account his host)', 'pete@silly.test')]),
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+
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+ (['(Empty list)(start)Undisclosed recipients :(nobody(I know))'],
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+ [('', '')]),
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+
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+ (['Mary <@machine.tld:mary@example.net>, , jdoe@test . example'],
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+ [('Mary', 'mary@example.net'), ('', ''), ('', 'jdoe@test.example')]),
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+
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+ (['John Doe <jdoe@machine(comment). example>'],
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+ [('John Doe (comment)', 'jdoe@machine.example')]),
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+
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+ (['"Mary Smith: Personal Account" <smith@home.example>'],
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+ [('Mary Smith: Personal Account', 'smith@home.example')]),
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+
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+ (['Undisclosed recipients:;'],
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+ [('', '')]),
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+
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+ ([r'<boss@nil.test>, "Giant; \"Big\" Box" <bob@example.net>'],
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+ [('', 'boss@nil.test'), ('Giant; "Big" Box', 'bob@example.net')]),
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+ ):
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+ with self.subTest(addresses=addresses):
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+ self.assertEqual(utils.getaddresses(addresses),
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+ expected)
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+ self.assertEqual(utils.getaddresses(addresses, strict=False),
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+ expected)
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+
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+ addresses = ['[]*-- =~$']
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+ self.assertEqual(utils.getaddresses(addresses),
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+ [('', '')])
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+ self.assertEqual(utils.getaddresses(addresses, strict=False),
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+ [('', ''), ('', ''), ('', '*--')])
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|
|
|
def test_getaddresses_embedded_comment(self):
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|
"""Test proper handling of a nested comment"""
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|
@@ -3551,6 +3674,54 @@ def test_mime_classes_policy_argument(self):
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m = cls(*constructor, policy=email.policy.default)
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self.assertIs(m.policy, email.policy.default)
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+ def test_iter_escaped_chars(self):
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+ self.assertEqual(list(utils._iter_escaped_chars(r'a\\b\"c\\"d')),
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+ [(0, 'a'),
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+ (2, '\\\\'),
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+ (3, 'b'),
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+ (5, '\\"'),
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+ (6, 'c'),
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+ (8, '\\\\'),
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+ (9, '"'),
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+ (10, 'd')])
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+ self.assertEqual(list(utils._iter_escaped_chars('a\\')),
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+ [(0, 'a'), (1, '\\')])
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+
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+ def test_strip_quoted_realnames(self):
|
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+ def check(addr, expected):
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+ self.assertEqual(utils._strip_quoted_realnames(addr), expected)
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+
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+ check('"Jane Doe" <jane@example.net>, "John Doe" <john@example.net>',
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+ ' <jane@example.net>, <john@example.net>')
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+ check(r'"Jane \"Doe\"." <jane@example.net>',
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+ ' <jane@example.net>')
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+
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+ # special cases
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+ check(r'before"name"after', 'beforeafter')
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+ check(r'before"name"', 'before')
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+ check(r'b"name"', 'b') # single char
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+ check(r'"name"after', 'after')
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+ check(r'"name"a', 'a') # single char
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+ check(r'"name"', '')
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+
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+ # no change
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+ for addr in (
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+ 'Jane Doe <jane@example.net>, John Doe <john@example.net>',
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+ 'lone " quote',
|
|
+ ):
|
|
+ self.assertEqual(utils._strip_quoted_realnames(addr), addr)
|
|
+
|
|
+
|
|
+ def test_check_parenthesis(self):
|
|
+ addr = 'alice@example.net'
|
|
+ self.assertTrue(utils._check_parenthesis(f'{addr} (Alice)'))
|
|
+ self.assertFalse(utils._check_parenthesis(f'{addr} )Alice('))
|
|
+ self.assertFalse(utils._check_parenthesis(f'{addr} (Alice))'))
|
|
+ self.assertFalse(utils._check_parenthesis(f'{addr} ((Alice)'))
|
|
+
|
|
+ # Ignore real name between quotes
|
|
+ self.assertTrue(utils._check_parenthesis(f'")Alice((" {addr}'))
|
|
+
|
|
|
|
# Test the iterator/generators
|
|
class TestIterators(TestEmailBase):
|
|
diff --git a/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst b/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst
|
|
new file mode 100644
|
|
index 0000000000..3d0e9e4078
|
|
--- /dev/null
|
|
+++ b/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst
|
|
@@ -0,0 +1,8 @@
|
|
+:func:`email.utils.getaddresses` and :func:`email.utils.parseaddr` now
|
|
+return ``('', '')`` 2-tuples in more situations where invalid email
|
|
+addresses are encountered instead of potentially inaccurate values. Add
|
|
+optional *strict* parameter to these two functions: use ``strict=False`` to
|
|
+get the old behavior, accept malformed inputs.
|
|
+``getattr(email.utils, 'supports_strict_parsing', False)`` can be use to check
|
|
+if the *strict* paramater is available. Patch by Thomas Dwyer and Victor
|
|
+Stinner to improve the CVE-2023-27043 fix.
|