diff options
| -rw-r--r-- | Lib/email/_header_value_parser.py | 17 | ||||
| -rw-r--r-- | Lib/email/parser.py | 1 | ||||
| -rw-r--r-- | Lib/test/test_email/test_policy.py | 20 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2019-04-08-13-00-13.bpo-36564._n67m_.rst | 3 |
4 files changed, 35 insertions, 6 deletions
diff --git a/Lib/email/_header_value_parser.py b/Lib/email/_header_value_parser.py index aefc457..37dc764 100644 --- a/Lib/email/_header_value_parser.py +++ b/Lib/email/_header_value_parser.py @@ -2846,15 +2846,22 @@ def _fold_as_ew(to_encode, lines, maxlen, last_ew, ew_combine_allowed, charset): trailing_wsp = to_encode[-1] to_encode = to_encode[:-1] new_last_ew = len(lines[-1]) if last_ew is None else last_ew + + encode_as = 'utf-8' if charset == 'us-ascii' else charset + + # The RFC2047 chrome takes up 7 characters plus the length + # of the charset name. + chrome_len = len(encode_as) + 7 + + if (chrome_len + 1) >= maxlen: + raise errors.HeaderParseError( + "max_line_length is too small to fit an encoded word") + while to_encode: remaining_space = maxlen - len(lines[-1]) - # The RFC2047 chrome takes up 7 characters plus the length - # of the charset name. - encode_as = 'utf-8' if charset == 'us-ascii' else charset - text_space = remaining_space - len(encode_as) - 7 + text_space = remaining_space - chrome_len if text_space <= 0: lines.append(' ') - # XXX We'll get an infinite loop here if maxlen is <= 7 continue to_encode_word = to_encode[:text_space] diff --git a/Lib/email/parser.py b/Lib/email/parser.py index 555b172..7db4da1 100644 --- a/Lib/email/parser.py +++ b/Lib/email/parser.py @@ -13,7 +13,6 @@ from email.feedparser import FeedParser, BytesFeedParser from email._policybase import compat32 - class Parser: def __init__(self, _class=None, *, policy=compat32): """Parser of RFC 2822 and MIME email messages. diff --git a/Lib/test/test_email/test_policy.py b/Lib/test/test_email/test_policy.py index 1e39aa0..e87c275 100644 --- a/Lib/test/test_email/test_policy.py +++ b/Lib/test/test_email/test_policy.py @@ -2,6 +2,7 @@ import io import types import textwrap import unittest +import email.errors import email.policy import email.parser import email.generator @@ -257,6 +258,25 @@ class PolicyAPITests(unittest.TestCase): 'Subject: \n' + 12 * ' =?utf-8?q?=C4=85?=\n') + def test_short_maxlen_error(self): + # RFC 2047 chrome takes up 7 characters, plus the length of the charset + # name, so folding should fail if maxlen is lower than the minimum + # required length for a line. + + # Note: This is only triggered when there is a single word longer than + # max_line_length, hence the 1234567890 at the end of this whimsical + # subject. This is because when we encounter a word longer than + # max_line_length, it is broken down into encoded words to fit + # max_line_length. If the max_line_length isn't large enough to even + # contain the RFC 2047 chrome (`?=<charset>?q??=`), we fail. + subject = "Melt away the pounds with this one simple trick! 1234567890" + + for maxlen in [3, 7, 9]: + with self.subTest(maxlen=maxlen): + policy = email.policy.default.clone(max_line_length=maxlen) + with self.assertRaises(email.errors.HeaderParseError): + policy.fold("Subject", subject) + # XXX: Need subclassing tests. # For adding subclassed objects, make sure the usual rules apply (subclass # wins), but that the order still works (right overrides left). diff --git a/Misc/NEWS.d/next/Library/2019-04-08-13-00-13.bpo-36564._n67m_.rst b/Misc/NEWS.d/next/Library/2019-04-08-13-00-13.bpo-36564._n67m_.rst new file mode 100644 index 0000000..ddd17ae --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-04-08-13-00-13.bpo-36564._n67m_.rst @@ -0,0 +1,3 @@ +Fix infinite loop in email header folding logic that would be triggered when +an email policy's max_line_length is not long enough to include the required +markup and any values in the message. Patch by Paul Ganssle |