[urlshortener] add support for bit.ly & t.co

docs/supportedsites.md

@@ -1270,6 +1270,22 @@ Consider all sites to be NSFW unless otherwise known.
     <td></td>
 </tr>
 
+<tr>
+    <td colspan="4"><strong>URL Shorteners</strong></td>
+</tr>
+<tr>
+    <td>Bitly</td>
+    <td>https://bit.ly/</td>
+    <td></td>
+    <td></td>
+</tr>
+<tr>
+    <td>Twitter t.co</td>
+    <td>https://t.co/</td>
+    <td></td>
+    <td></td>
+</tr>
+
 <tr>
     <td colspan="4"><strong>vichan Imageboards</strong></td>
 </tr>

gallery_dl/extractor/__init__.py

@@ -153,6 +153,7 @@ modules = [
     "twitter",
     "unsplash",
     "uploadir",
+    "urlshortener",
     "vanillarock",
     "vichan",
     "vk",

gallery_dl/extractor/urlshortener.py

@@ -0,0 +1,59 @@
+# -*- coding: utf-8 -*-
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+"""Extractor for general-purpose URL shorteners"""
+
+from .common import BaseExtractor, Message
+from .. import exception
+
+
+class UrlshortenerExtractor(BaseExtractor):
+    """Base class for general-purpose URL shorteners"""
+    basecategory = "urlshortener"
+    test = (
+        ("https://bit.ly/3cWIUgq", {
+            "count": 1,
+            "pattern": "^https://gumroad.com/l/storm_b1"
+        }),
+        ("https://t.co/bCgBY8Iv5n", {
+            "count": 1,
+            "pattern": ("^https://twitter.com/elonmusk/status/"
+                        "1421395561324896257/photo/1")
+        }),
+    )
+
+    def __init__(self, match):
+        BaseExtractor.__init__(self, match)
+        self.headers = INSTANCES[self.category].get("headers")
+        self.url = match.group()
+
+    def request(self, url, **kwargs):
+        kwargs["headers"] = self.headers
+        return BaseExtractor.request(self, url, **kwargs)
+
+    def items(self):
+        response = self.request(
+            self.url, method="HEAD", allow_redirects=False, notfound="URL")
+        if "location" not in response.headers:
+            raise exception.StopExtraction("Unable to resolve short URL")
+        yield Message.Queue, response.headers["location"], {}
+
+
+INSTANCES = {
+    "bitly": {
+        "root": "https://bit.ly",
+        "pattern": r"bit\.ly",
+    },
+    "tco": {
+        # t.co sends 'http-equiv="refresh"' (200) when using browser UA
+        "headers": {"User-Agent": None},
+        "root": "https://t.co",
+        "pattern": r"t\.co",
+    },
+}
+
+UrlshortenerExtractor.pattern = \
+    UrlshortenerExtractor.update(INSTANCES) + r"/[^/?#&]+"

scripts/supportedsites.py

@@ -112,6 +112,7 @@ CATEGORY_MAP = {
     "subscribestar"  : "SubscribeStar",
     "tbib"           : "The Big ImageBoard",
     "tcbscans"       : "TCB Scans",
+    "tco"            : "Twitter t.co",
     "thatpervert"    : "ThatPervert",
     "thebarchive"    : "The /b/ Archive",
     "thecollection"  : "The /co/llection",
@@ -132,6 +133,7 @@ CATEGORY_MAP = {
 }
 
 SUBCATEGORY_MAP = {
+    ""       : "",
     "art"    : "Art",
     "audio"  : "Audio",
     "doujin" : "Doujin",
@@ -266,6 +268,7 @@ BASE_MAP = {
     "lynxchan"    : "LynxChan Imageboards",
     "moebooru"    : "Moebooru and MyImouto",
     "szurubooru"  : "szurubooru Instances",
+    "urlshortener": "URL Shorteners",
     "vichan"      : "vichan Imageboards",
 }