[networking] Rewrite architecture (#2861)

New networking interface consists of a `RequestDirector` that directs
each `Request` to appropriate `RequestHandler` and returns the
`Response` or raises `RequestError`. The handlers define adapters to
transform its internal Request/Response/Errors to our interfaces.

User-facing changes:
- Fix issues with per request proxies on redirects for urllib
- Support for `ALL_PROXY` environment variable for proxy setting
- Support for `socks5h` proxy
   - Closes https://github.com/yt-dlp/yt-dlp/issues/6325, https://github.com/ytdl-org/youtube-dl/issues/22618, https://github.com/ytdl-org/youtube-dl/pull/28093
- Raise error when using `https` proxy instead of silently converting it to `http`

Authored by: coletdjnz

yt_dlp/downloader/http.py

@@ -1,12 +1,10 @@
-import http.client
 import os
 import random
-import socket
-import ssl
 import time
 import urllib.error
 
 from .common import FileDownloader
+from ..networking.exceptions import CertificateVerifyError, TransportError
 from ..utils import (
     ContentTooShortError,
     RetryManager,
@@ -21,14 +19,6 @@ from ..utils import (
     write_xattr,
 )
 
-RESPONSE_READ_EXCEPTIONS = (
-    TimeoutError,
-    socket.timeout,  # compat: py < 3.10
-    ConnectionError,
-    ssl.SSLError,
-    http.client.HTTPException
-)
-
 
 class HttpFD(FileDownloader):
     def real_download(self, filename, info_dict):
@@ -196,13 +186,9 @@ class HttpFD(FileDownloader):
                     # Unexpected HTTP error
                     raise
                 raise RetryDownload(err)
-            except urllib.error.URLError as err:
-                if isinstance(err.reason, ssl.CertificateError):
-                    raise
-                raise RetryDownload(err)
-            # In urllib.request.AbstractHTTPHandler, the response is partially read on request.
-            # Any errors that occur during this will not be wrapped by URLError
-            except RESPONSE_READ_EXCEPTIONS as err:
+            except CertificateVerifyError:
+                raise
+            except TransportError as err:
                 raise RetryDownload(err)
 
         def close_stream():
@@ -258,7 +244,7 @@ class HttpFD(FileDownloader):
                 try:
                     # Download and write
                     data_block = ctx.data.read(block_size if not is_test else min(block_size, data_len - byte_counter))
-                except RESPONSE_READ_EXCEPTIONS as err:
+                except TransportError as err:
                     retry(err)
 
                 byte_counter += len(data_block)