Add --enable-file-urls (#5917)

Closes https://github.com/yt-dlp/yt-dlp/issues/3675

Authored by: coletdjnz

README.md

@@ -419,6 +419,8 @@ ## Network Options:
     --source-address IP             Client-side IP address to bind to
     -4, --force-ipv4                Make all connections via IPv4
     -6, --force-ipv6                Make all connections via IPv6
+    --enable-file-urls              Enable file:// URLs. This is disabled by
+                                    default for security reasons.
 
 ## Geo-restriction:
     --geo-verification-proxy URL    Use this proxy to verify the IP address for

yt_dlp/YoutubeDL.py

@@ -318,6 +318,7 @@ class YoutubeDL:
                         If not provided and the key is encrypted, yt-dlp will ask interactively
     prefer_insecure:   Use HTTP instead of HTTPS to retrieve information.
                        (Only supported by some extractors)
+    enable_file_urls:  Enable file:// URLs. This is disabled by default for security reasons.
     http_headers:      A dictionary of custom headers to be used for all requests
     proxy:             URL of the proxy server to use
     geo_verification_proxy:  URL of the proxy to use for IP address verification
@@ -3875,9 +3876,12 @@ def _setup_opener(self):
         # https://github.com/ytdl-org/youtube-dl/issues/8227)
         file_handler = urllib.request.FileHandler()
 
-        def file_open(*args, **kwargs):
-            raise urllib.error.URLError('file:// scheme is explicitly disabled in yt-dlp for security reasons')
-        file_handler.file_open = file_open
+        if not self.params.get('enable_file_urls'):
+            def file_open(*args, **kwargs):
+                raise urllib.error.URLError(
+                    'file:// URLs are explicitly disabled in yt-dlp for security reasons. '
+                    'Use --enable-file-urls to enable at your own risk.')
+            file_handler.file_open = file_open
 
         opener = urllib.request.build_opener(
             proxy_handler, https_handler, cookie_processor, ydlh, redirect_handler, data_handler, file_handler)

yt_dlp/__init__.py

@@ -855,6 +855,7 @@ def parse_options(argv=None):
         'legacyserverconnect': opts.legacy_server_connect,
         'nocheckcertificate': opts.no_check_certificate,
         'prefer_insecure': opts.prefer_insecure,
+        'enable_file_urls': opts.enable_file_urls,
         'http_headers': opts.headers,
         'proxy': opts.proxy,
         'socket_timeout': opts.socket_timeout,

yt_dlp/options.py

@@ -516,6 +516,11 @@ def _alias_callback(option, opt_str, value, parser, opts, nargs):
         action='store_const', const='::', dest='source_address',
         help='Make all connections via IPv6',
     )
+    network.add_option(
+        '--enable-file-urls', action='store_true',
+        dest='enable_file_urls', default=False,
+        help='Enable file:// URLs. This is disabled by default for security reasons.'
+    )
 
     geo = optparse.OptionGroup(parser, 'Geo-restriction')
     geo.add_option(