Handle user:pass in URLs

Fixes ytdl-org#18276 (point 4)
Fixes ytdl-org#20258
Fixes ytdl-org#26211 (see comment)

youtube_dl/utils.py

@@ -2155,7 +2155,31 @@ def sanitize_url(url):
 
 
 def sanitized_Request(url, *args, **kwargs):
-    return compat_urllib_request.Request(sanitize_url(url), *args, **kwargs)
+    url = sanitize_url(url)
+    parts = compat_urllib_parse.urlsplit(url)
+    username = parts.username
+    password = parts.password
+    if username is not None:
+        # Remove "user:pass" from "url" since they are not recognized by
+        # "compat_urllib_request.Request".
+        netloc = parts.hostname
+        if parts.port is not None:
+            netloc = parts.hostname + ':' + parts.port
+        parts = parts._replace(netloc=netloc)
+        url = compat_urllib_parse.urlunsplit(parts)
+        # Add the Authorization header.
+        if password is None:
+            password = ''
+        auth_payload = username + ':' + password
+        auth_payload = base64.b64encode(bytes(auth_payload, 'utf-8')).decode('utf-8')
+        auth_header = 'Basic ' + auth_payload
+        if len(args) >= 2:
+            args[1]['Authorization'] = auth_header
+        else:
+            if 'headers' not in kwargs:
+                kwargs['headers'] = {}
+            kwargs['headers']['Authorization'] = 'Basic ' + auth_payload
+    return compat_urllib_request.Request(url, *args, **kwargs)
 
 
 def expand_path(s):