[downloader/fragment] Fix bugs around resuming with Range (#2901)

Authored by: Lesmiscore

yt_dlp/utils.py

@@ -5252,6 +5252,16 @@ def join_nonempty(*values, delim='-', from_dict=None):
     return delim.join(map(str, filter(None, values)))
 
 
+def parse_http_range(range):
+    """ Parse value of "Range" or "Content-Range" HTTP header into tuple. """
+    if not range:
+        return None, None, None
+    crg = re.search(r'bytes[ =](\d+)-(\d+)?(?:/(\d+))?', range)
+    if not crg:
+        return None, None, None
+    return int(crg.group(1)), int_or_none(crg.group(2)), int_or_none(crg.group(3))
+
+
 class Config:
     own_args = None
     filename = None