Replace a call to cgi.parse_header()

Fixes #330

Author: kurtmckee

changelog.d/20220521_105155_kurtmckee_fix_python_3_11_cgi_deprecation.rst

@@ -0,0 +1,4 @@
+Fixed
+-----
+
+* Replace a call to ``cgi.parse_header()``, which causes deprecation warnings in Python 3.11.

feedparser/encodings.py

@@ -26,9 +26,9 @@
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-import cgi
 import codecs
 import re
+import typing as t
 
 try:
  try:
@@ -68,6 +68,30 @@ def lazy_chardet_encoding(data):
 RE_XML_PI_ENCODING = re.compile(br'^<\?.*encoding=[\'"](.*?)[\'"].*\?>')
 
 
+def parse_content_type(line: str) -> t.Tuple[str, str]:
+ """Parse an HTTP Content-Type header.
+
+ The return value will be a tuple of strings:
+ the MIME type, and the value of the "charset" (if any).
+
+ This is a custom replacement for Python's cgi.parse_header().
+ The cgi module will be removed in Python 3.13.
+ """
+
+ chunks = line.split(";")
+ if not chunks:
+ return "", ""
+
+ mime_type = chunks[0].strip()
+ charset_value = ""
+ for chunk in chunks[1:]:
+ key, _, value = chunk.partition("=")
+ if key.strip().lower() == "charset":
+ charset_value = value.strip().strip("\"'")
+
+ return mime_type, charset_value
+
+
 def convert_to_utf8(http_headers, data, result):
  """Detect and convert the character encoding to UTF-8.
 
@@ -181,10 +205,7 @@ def convert_to_utf8(http_headers, data, result):
  # XML declaration encoding, and HTTP encoding, following the
  # heuristic defined in RFC 3023.
  http_content_type = http_headers.get('content-type') or ''
- http_content_type, params = cgi.parse_header(http_content_type)
- http_encoding = params.get('charset', '').replace("'", "")
- if isinstance(http_encoding, bytes):
- http_encoding = http_encoding.decode('utf-8', 'ignore')
+ http_content_type, http_encoding = parse_content_type(http_content_type)
 
  acceptable_content_type = 0
  application_content_types = ('application/xml', 'application/xml-dtd',