Fixed issue #132 and #133 (#151)

* Issue #132

* fix: Update address parsing to skip empty entries from absent headers

Author: fedelemantuano

src/mailparser/core.py

@@ -18,7 +18,6 @@
 
 import base64
 import email
-import email.utils
 import ipaddress
 import json
 import logging
@@ -29,6 +28,7 @@
     convert_mail_date,
     decode_header_part,
     find_between,
+    get_addresses,
     get_header,
     get_mail_keys,
     get_to_domains,
@@ -569,10 +569,17 @@ def __getattr__(self, name):
         # object headers
         elif name_header in ADDRESSES_HEADERS:
             raw_header = self.message.get(name_header, "") if self.message else ""
-            # parse before decoding
-            parsed_addresses = email.utils.getaddresses([raw_header], strict=True)
-
-            # decoded addresses
+            # Parse addresses. RFC 5322 §3.4 does not allow unquoted "@" in
+            # display names, so a strict parser correctly rejects headers like
+            #   From: alice@example.com <bob@example.com>
+            # and returns ('', '').  mail-parser is a security/forensics tool,
+            # not an MTA: hiding addresses from analysts is worse than accepting
+            # non-conforming input.  get_addresses() applies a regex fallback
+            # when strict parsing yields only empty results — see its docstring
+            # in utils.py for the full rationale.
+            parsed_addresses = get_addresses(raw_header)
+
+            # decoded addresses — skip entries with no address (absent header)
             return [
                 (
                     (
@@ -583,6 +590,7 @@ def __getattr__(self, name):
                     email_addr,
                 )
                 for name, email_addr in parsed_addresses
+                if email_addr
             ]
 
         # others headers

src/mailparser/utils.py

@@ -50,6 +50,88 @@
 
 log = logging.getLogger(__name__)
 
+# ---------------------------------------------------------------------------
+# RFC 5322 address parsing — fallback for non-compliant display names
+# ---------------------------------------------------------------------------
+# RFC 5322 §3.4 defines the display-name as a "phrase", which must not contain
+# unquoted special characters such as "@".  A header like
+#
+#     From: alice@example.com <bob@example.com>
+#
+# is therefore *technically non-conforming*: the display name contains an
+# unquoted "@".  Python's ``email.utils.getaddresses`` with ``strict=True``
+# (hardened against CVE-2023-27043) correctly rejects this and returns
+# ``[('', '')]``, leaving the real address invisible.
+#
+# mail-parser is a security / forensics tool, not an MTA.  Silently hiding an
+# address because its display-name looks like an e-mail address defeats the
+# purpose of the tool — analysts *need* to see those values.  We therefore
+# bypass strict compliance with a regex fallback whenever strict parsing yields
+# an empty address, always surfacing the value that is actually in the header.
+_ADDR_FALLBACK_RE = re.compile(
+    r'"([^"]*?)"\s*<([^>]+)>'  # "Quoted Name" <email@addr>
+    r"|([^<,]*?)\s*<([^>]+)>"  # Any Name <email@addr>  (incl. email-as-name)
+    r"|([^\s,<>]+@[^\s,<>]+)"  # bare email@addr
+)
+
+
+def get_addresses(raw_header):
+    """
+    Parse email addresses from a raw address header with a fallback for
+    RFC-non-compliant but real-world-common formats.
+
+    RFC 5322 §3.4 requires the display name (phrase) before an angle-bracket
+    address to consist only of printable ASCII characters that are *not*
+    special.  The ``@`` character is special, so a header such as::
+
+        From: alice@example.com <bob@example.com>
+
+    is technically non-conforming because the display name contains an
+    unquoted ``@``.  Python's ``email.utils.getaddresses`` with
+    ``strict=True`` (hardened against CVE-2023-27043) correctly returns
+    ``[('', '')]`` for this input, making the real sender invisible.
+
+    mail-parser is a *security / forensics* tool, not an MTA.  Silently
+    discarding an address because its display name happens to look like an
+    e-mail address would hide relevant forensic information from analysts —
+    the very opposite of what the tool is for.  We therefore bypass strict
+    RFC compliance by applying a regex-based fallback whenever the strict
+    parser yields only empty addresses, so that analysts always see the value
+    that was actually present in the header.
+
+    Args:
+        raw_header (str): raw value of an address header
+            (e.g. ``From``, ``To``, ``CC`` …)
+
+    Returns:
+        list[tuple[str, str]]: list of ``(display_name, email_addr)`` tuples.
+            ``display_name`` is an empty string when absent.
+    """
+    parsed = email.utils.getaddresses([raw_header], strict=True)
+
+    # If every result from the strict parser has an empty address — while the
+    # raw header is non-empty — fall back to regex extraction so that the
+    # actual address values are not silently lost.
+    if raw_header.strip() and all(not addr for _, addr in parsed):
+        results = []
+        for m in _ADDR_FALLBACK_RE.finditer(raw_header):
+            if m.group(2):  # "Quoted Name" <email>
+                results.append((m.group(1).strip(), m.group(2).strip()))
+            elif m.group(4):  # Any Name <email>  (incl. email-as-display-name)
+                results.append((m.group(3).strip(), m.group(4).strip()))
+            elif m.group(5):  # bare email
+                results.append(("", m.group(5).strip()))
+        if results:
+            log.debug(
+                "Strict address parsing yielded empty results for %r; "
+                "regex fallback recovered %d address(es)",
+                raw_header,
+                len(results),
+            )
+            return results
+
+    return parsed
+
 
 def custom_log(level="WARNING", name=None):  # pragma: no cover
     """

tests/mails/mail_test_19

@@ -0,0 +1,12 @@
+From: alice@example.com <bob@example.com>
+To: "Charlie Brown" <charlie@example.com>, dave@example.com
+CC: eve@example.com <frank@example.com>
+Reply-To: henry@example.com <ivan@example.com>
+Subject: Test email with email address as display name
+Message-ID: <test-email-as-name@example.com>
+Date: Mon, 01 Jan 2024 12:00:00 +0000
+MIME-Version: 1.0
+Content-Type: text/plain; charset=utf-8
+
+This email tests parsing of address headers where the display name is itself
+an email address (RFC non-compliant but common in real-world mail).

tests/test_mail_parser.py

@@ -29,6 +29,7 @@
 from mailparser.utils import (
     convert_mail_date,
     fingerprints,
+    get_addresses,
     get_header,
     get_mail_keys,
     get_to_domains,
@@ -62,6 +63,7 @@
 mail_test_16 = os.path.join(base_path, "mails", "mail_test_16")
 mail_test_17 = os.path.join(base_path, "mails", "mail_test_17")
 mail_test_18 = os.path.join(base_path, "mails", "mail_test_18")
+mail_test_19 = os.path.join(base_path, "mails", "mail_test_19")
 mail_malformed_1 = os.path.join(base_path, "mails", "mail_malformed_1")
 mail_malformed_2 = os.path.join(base_path, "mails", "mail_malformed_2")
 mail_malformed_3 = os.path.join(base_path, "mails", "mail_malformed_3")
@@ -1084,3 +1086,162 @@ def test_unicode_decode_error_in_payload(self):
         mail = mailparser.parse_from_string(raw_mail)
         # Should have parsed successfully and body contains the text
         self.assertIn("hello", mail.body)
+
+
+class TestEmailAsDisplayName(unittest.TestCase):
+    """
+    Tests for address parsing when the display name is itself an email address.
+
+    RFC 5322 §3.4 forbids unquoted "@" in the display-name phrase, so a header
+    like ``From: alice@example.com <bob@example.com>`` is technically
+    non-conforming.  Python's strict parser (CVE-2023-27043 hardening) returns
+    ``[('', '')]`` for such input, which would silently hide the real sender.
+
+    mail-parser is a security/forensics tool: it intentionally bypasses this
+    strict compliance and applies a regex fallback so that analysts always see
+    the address values that are actually present in the header.
+    """
+
+    def test_from_email_as_display_name(self):
+        """From header with an email address as display name is parsed correctly."""
+        mail = mailparser.parse_from_file(mail_test_19)
+        result = mail.from_
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "bob@example.com")
+        self.assertEqual(name, "alice@example.com")
+
+    def test_cc_email_as_display_name(self):
+        """CC header with an email address as display name is parsed correctly."""
+        mail = mailparser.parse_from_file(mail_test_19)
+        result = mail.cc
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "frank@example.com")
+        self.assertEqual(name, "eve@example.com")
+
+    def test_reply_to_email_as_display_name(self):
+        """Reply-To header with an email address as display name is parsed correctly."""
+        mail = mailparser.parse_from_file(mail_test_19)
+        result = mail.reply_to
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "ivan@example.com")
+        self.assertEqual(name, "henry@example.com")
+
+    def test_to_mixed_addresses(self):
+        """To header with a mix of quoted name and bare address is parsed correctly."""
+        mail = mailparser.parse_from_file(mail_test_19)
+        result = mail.to
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 2)
+        # "Charlie Brown" <charlie@example.com>
+        name0, addr0 = result[0]
+        self.assertEqual(addr0, "charlie@example.com")
+        self.assertEqual(name0, "Charlie Brown")
+        # dave@example.com  (bare address, no display name)
+        name1, addr1 = result[1]
+        self.assertEqual(addr1, "dave@example.com")
+        self.assertEqual(name1, "")
+
+    # ------------------------------------------------------------------
+    # Edge-case tests via parse_from_string (no additional mail files needed)
+    # ------------------------------------------------------------------
+
+    def test_same_email_as_name_and_address_suppresses_name(self):
+        """When display name == address, name is suppressed to empty string.
+
+        This covers the case ``From: bob@example.com <bob@example.com>`` which
+        is both RFC non-compliant (unquoted @) AND redundant.  After the regex
+        fallback recovers the address, the existing name-suppression logic
+        (decoded_name == email_addr → "") must still fire correctly.
+        """
+        mail = mailparser.parse_from_string(
+            "From: bob@example.com <bob@example.com>\nSubject: x\n\nBody"
+        )
+        result = mail.from_
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "bob@example.com")
+        self.assertEqual(name, "")
+
+    def test_quoted_email_as_display_name(self):
+        """Properly quoted email-as-name (RFC-compliant) is parsed by strict parser."""
+        mail = mailparser.parse_from_string(
+            'From: "alice@example.com" <bob@example.com>\nSubject: x\n\nBody'
+        )
+        result = mail.from_
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "bob@example.com")
+        self.assertEqual(name, "alice@example.com")
+
+    def test_standard_display_name_unchanged(self):
+        """Standard ``Name <email>`` format still works correctly (no regression)."""
+        mail = mailparser.parse_from_string(
+            "From: Alice Smith <alice@example.com>\nSubject: x\n\nBody"
+        )
+        result = mail.from_
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "alice@example.com")
+        self.assertEqual(name, "Alice Smith")
+
+    def test_bare_address_no_display_name(self):
+        """Bare address with no display name returns empty name (no regression)."""
+        mail = mailparser.parse_from_string(
+            "From: alice@example.com\nSubject: x\n\nBody"
+        )
+        result = mail.from_
+        self.assertEqual(len(result), 1)
+        name, addr = result[0]
+        self.assertEqual(addr, "alice@example.com")
+        self.assertEqual(name, "")
+
+    def test_empty_header_returns_empty_list(self):
+        """A missing address header returns [] — absent headers must not appear."""
+        mail = mailparser.parse_from_string("Subject: x\n\nBody")
+        # Python's getaddresses("") yields [('', '')], but we filter out entries
+        # with an empty address so that absent headers are not included in the
+        # parsed mail object.
+        self.assertEqual(mail.from_, [])
+
+    # ------------------------------------------------------------------
+    # Unit tests for get_addresses() helper directly
+    # ------------------------------------------------------------------
+
+    def test_get_addresses_email_as_name(self):
+        """get_addresses() fallback recovers address when display name is an email."""
+        result = get_addresses("alice@example.com <bob@example.com>")
+        self.assertEqual(result, [("alice@example.com", "bob@example.com")])
+
+    def test_get_addresses_standard_format(self):
+        """get_addresses() strict path handles normal ``Name <email>`` correctly."""
+        result = get_addresses("Alice Smith <alice@example.com>")
+        self.assertEqual(result, [("Alice Smith", "alice@example.com")])
+
+    def test_get_addresses_bare_email(self):
+        """get_addresses() handles bare email address with no display name."""
+        result = get_addresses("alice@example.com")
+        self.assertEqual(result, [("", "alice@example.com")])
+
+    def test_get_addresses_empty_header(self):
+        """get_addresses() on empty string returns [('', '')] — raw Python lib result.
+
+        The ('', '') entry is filtered out in __getattr__ (core.py) so that
+        absent headers do not appear in the parsed mail output.
+        """
+        result = get_addresses("")
+        self.assertEqual(result, [("", "")])
+
+    def test_get_addresses_multiple_with_email_as_name(self):
+        """get_addresses() fallback handles multiple addresses when all fail strict."""
+        result = get_addresses(
+            "alice@example.com <bob@example.com>, eve@example.com <frank@example.com>"
+        )
+        self.assertEqual(len(result), 2)
+        self.assertEqual(result[0], ("alice@example.com", "bob@example.com"))
+        self.assertEqual(result[1], ("eve@example.com", "frank@example.com"))