[utils] Rework URL path munging for ., .. components

* move processing to YoutubeDLHandler
* also process `Location` header for redirect
* use tests from https://github.com/yt-dlp/yt-dlp/pull/7662

4 files changed, 95 insertions, 41 deletions

diff --git a/test/test_http.py b/test/test_http.py
index 793bea359..485c4c6fc 100644
--- a/test/test_http.py
+++ b/test/test_http.py
@@ -180,6 +180,12 @@ class HTTPTestRequestHandler(compat_http_server.BaseHTTPRequestHandler):
             respond()
         elif self.path == '/%c7%9f':
             respond()
+        elif self.path == '/redirect_dotsegments':
+            self.send_response(301)
+            # redirect to /headers but with dot segments before
+            self.send_header('Location', '/a/b/./../../headers')
+            self.send_header('Content-Length', '0')
+            self.end_headers()
         elif self.path.startswith('/redirect_'):
             self._redirect()
         elif self.path.startswith('/method'):
@@ -489,6 +495,14 @@ class TestHTTP(unittest.TestCase):
             self.assertEqual(res.headers.get('Content-Encoding'), 'unsupported')
             self.assertEqual(res.read(), b'raw')
 
+    def test_remove_dot_segments(self):
+        with FakeYDL() as ydl:
+            res = ydl.urlopen(sanitized_Request(self._test_url('a/b/./../../headers')))
+            self.assertEqual(compat_urllib_parse.urlparse(res.geturl()).path, '/headers')
+
+            res = ydl.urlopen(sanitized_Request(self._test_url('redirect_dotsegments')))
+            self.assertEqual(compat_urllib_parse.urlparse(res.geturl()).path, '/headers')
+
 
 def _build_proxy_handler(name):
     class HTTPTestRequestHandler(compat_http_server.BaseHTTPRequestHandler):
diff --git a/test/test_utils.py b/test/test_utils.py
index e83977f29..fdae1f744 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -64,6 +64,7 @@ from youtube_dl.utils import (
     parse_age_limit,
     parse_duration,
     parse_filesize,
+    parse_codecs,
     parse_count,
     parse_iso8601,
     parse_resolution,
@@ -114,7 +115,7 @@ from youtube_dl.utils import (
     cli_option,
     cli_valueless_option,
     cli_bool_option,
-    parse_codecs,
+    YoutubeDLHandler,
 )
 from youtube_dl.compat import (
     compat_chr,
@@ -905,6 +906,32 @@ class TestUtil(unittest.TestCase):
         )
         self.assertEqual(escape_url('http://vimeo.com/56015672#at=0'), 'http://vimeo.com/56015672#at=0')
 
+    def test_remove_dot_segments(self):
+
+        def remove_dot_segments(p):
+            q = '' if p.startswith('/') else '/'
+            p = 'http://example.com' + q + p
+            p = compat_urlparse.urlsplit(YoutubeDLHandler._fix_path(p)).path
+            return p[1:] if q else p
+
+        self.assertEqual(remove_dot_segments('/a/b/c/./../../g'), '/a/g')
+        self.assertEqual(remove_dot_segments('mid/content=5/../6'), 'mid/6')
+        self.assertEqual(remove_dot_segments('/ad/../cd'), '/cd')
+        self.assertEqual(remove_dot_segments('/ad/../cd/'), '/cd/')
+        self.assertEqual(remove_dot_segments('/..'), '/')
+        self.assertEqual(remove_dot_segments('/./'), '/')
+        self.assertEqual(remove_dot_segments('/./a'), '/a')
+        self.assertEqual(remove_dot_segments('/abc/./.././d/././e/.././f/./../../ghi'), '/ghi')
+        self.assertEqual(remove_dot_segments('/'), '/')
+        self.assertEqual(remove_dot_segments('/t'), '/t')
+        self.assertEqual(remove_dot_segments('t'), 't')
+        self.assertEqual(remove_dot_segments(''), '')
+        self.assertEqual(remove_dot_segments('/../a/b/c'), '/a/b/c')
+        self.assertEqual(remove_dot_segments('../a'), 'a')
+        self.assertEqual(remove_dot_segments('./a'), 'a')
+        self.assertEqual(remove_dot_segments('.'), '')
+        self.assertEqual(remove_dot_segments('////'), '////')
+
     def test_js_to_json_vars_strings(self):
         self.assertDictEqual(
             json.loads(js_to_json(
diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index 6a12f91e4..13a41928f 100755
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -71,7 +71,6 @@ from .utils import (
     format_bytes,
     formatSeconds,
     GeoRestrictedError,
-    HEADRequest,
     int_or_none,
     ISO3166Utils,
     join_nonempty,
@@ -88,7 +87,6 @@ from .utils import (
     preferredencoding,
     prepend_extension,
     process_communicate_or_kill,
-    PUTRequest,
     register_socks_protocols,
     render_table,
     replace_extension,
@@ -2460,27 +2458,6 @@ class YoutubeDL(object):
         """ Start an HTTP download """
         if isinstance(req, compat_basestring):
             req = sanitized_Request(req)
-        # an embedded /../ sequence is not automatically handled by urllib2
-        # see https://github.com/yt-dlp/yt-dlp/issues/3355
-        url = req.get_full_url()
-        parts = url.partition('/../')
-        if parts[1]:
-            url = compat_urllib_parse.urljoin(parts[0] + parts[1][:1], parts[1][1:] + parts[2])
-        if url:
-            # worse, URL path may have initial /../ against RFCs: work-around
-            # by stripping such prefixes, like eg Firefox
-            parts = compat_urllib_parse.urlsplit(url)
-            path = parts.path
-            while path.startswith('/../'):
-                path = path[3:]
-            url = parts._replace(path=path).geturl()
-            # get a new Request with the munged URL
-            if url != req.get_full_url():
-                req_type = {'HEAD': HEADRequest, 'PUT': PUTRequest}.get(
-                    req.get_method(), compat_urllib_request.Request)
-                req = req_type(
-                    url, data=req.data, headers=dict(req.header_items()),
-                    origin_req_host=req.origin_req_host, unverifiable=req.unverifiable)
         return self._opener.open(req, timeout=self._socket_timeout)
 
     def print_debug_header(self):
diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index e73291107..36204c8fa 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -2678,17 +2678,52 @@ class YoutubeDLHandler(compat_urllib_request.HTTPHandler):
     def compress(data):
         return data and ncompress.decompress(data)
 
+    @staticmethod
+    def _fix_path(url):
+        # an embedded /../ or /./ sequence is not automatically handled by urllib2
+        # see https://github.com/yt-dlp/yt-dlp/issues/3355
+        parsed_url = compat_urllib_parse.urlsplit(url)
+        path = parsed_url.path
+        if not path.endswith('/'):
+            path += '/'
+        parts = path.partition('/./')
+        if not parts[1]:
+            parts = path.partition('/../')
+        if parts[1]:
+            path = compat_urllib_parse.urljoin(
+                parts[0] + parts[1][:1],
+                parts[1][1:] + (parts[2] if parsed_url.path.endswith('/') else parts[2][:-1]))
+            url = parsed_url._replace(path=path).geturl()
+        if '/.' in url:
+            # worse, URL path may have initial /../ against RFCs: work-around
+            # by stripping such prefixes, like eg Firefox
+            path = parsed_url.path + '/'
+            while path.startswith('/.'):
+                if path.startswith('/../'):
+                    path = path[3:]
+                elif path.startswith('/./'):
+                    path = path[2:]
+                else:
+                    break
+            path = path[:-1]
+            if not path.startswith('/') and parsed_url.path.startswith('/'):
+                path = '/' + path
+            url = parsed_url._replace(path=path).geturl()
+        return url
+
     def http_request(self, req):
-        # According to RFC 3986, URLs can not contain non-ASCII characters, however this is not
-        # always respected by websites, some tend to give out URLs with non percent-encoded
+        url = req.get_full_url()
+        # resolve embedded . and ..
+        url_fixed = self._fix_path(url)
+        # According to RFC 3986, URLs can not contain non-ASCII characters; however this is not
+        # always respected by websites: some tend to give out URLs with non percent-encoded
         # non-ASCII characters (see telemb.py, ard.py [#3412])
         # urllib chokes on URLs with non-ASCII characters (see http://bugs.python.org/issue3991)
         # To work around aforementioned issue we will replace request's original URL with
         # percent-encoded one
         # Since redirects are also affected (e.g. http://www.southpark.de/alle-episoden/s18e09)
         # the code of this workaround has been moved here from YoutubeDL.urlopen()
-        url = req.get_full_url()
-        url_escaped = escape_url(url)
+        url_escaped = escape_url(url_fixed)
 
         # Substitute URL if any change after escaping
         if url != url_escaped:
@@ -2702,10 +2737,13 @@ class YoutubeDLHandler(compat_urllib_request.HTTPHandler):
 
         req.headers = handle_youtubedl_headers(req.headers)
 
-        if sys.version_info < (2, 7) and '#' in req.get_full_url():
-            # Python 2.6 is brain-dead when it comes to fragments
-            req._Request__original = req._Request__original.partition('#')[0]
-            req._Request__r_type = req._Request__r_type.partition('#')[0]
+        if sys.version_info < (2, 7):
+            # avoid possible race where __r_type may be unset
+            req.get_type()
+            if '#' in req.get_full_url():
+                # Python 2.6 is brain-dead when it comes to fragments
+                req._Request__original = req._Request__original.partition('#')[0]
+                req._Request__r_type = req._Request__r_type.partition('#')[0]
 
         # Use the totally undocumented AbstractHTTPHandler per
         # https://github.com/yt-dlp/yt-dlp/pull/4158
@@ -2775,10 +2813,13 @@ class YoutubeDLHandler(compat_urllib_request.HTTPHandler):
                 if sys.version_info >= (3, 0):
                     location = location.encode('iso-8859-1')
                 location = location.decode('utf-8')
-                location_escaped = escape_url(location)
+                # resolve embedded . and ..
+                location_fixed = self._fix_path(location)
+                location_escaped = escape_url(location_fixed)
                 if location != location_escaped:
                     del resp.headers['Location']
-                    if sys.version_info < (3, 0):
+                    # if sys.version_info < (3, 0):
+                    if not isinstance(location_escaped, str):
                         location_escaped = location_escaped.encode('utf-8')
                     resp.headers['Location'] = location_escaped
         return resp
@@ -4248,13 +4289,8 @@ def update_Request(req, url=None, data=None, headers={}, query={}):
     req_headers.update(headers)
     req_data = data if data is not None else req.data
     req_url = update_url_query(url or req.get_full_url(), query)
-    req_get_method = req.get_method()
-    if req_get_method == 'HEAD':
-        req_type = HEADRequest
-    elif req_get_method == 'PUT':
-        req_type = PUTRequest
-    else:
-        req_type = compat_urllib_request.Request
+    req_type = {'HEAD': HEADRequest, 'PUT': PUTRequest}.get(
+        req.get_method(), compat_urllib_request.Request)
     new_req = req_type(
         req_url, data=req_data, headers=req_headers,
         origin_req_host=req.origin_req_host, unverifiable=req.unverifiable)