diff --git a/scrapy/utils/response.py b/scrapy/utils/response.py
index c068d9b1e..f5632da75 100644
--- a/scrapy/utils/response.py
+++ b/scrapy/utils/response.py
@@ -28,7 +28,7 @@ _baseurl_cache: WeakKeyDictionary[Response, str] = WeakKeyDictionary()
def get_base_url(response: TextResponse) -> str:
"""Return the base url of the given response, joined with the response url"""
if response not in _baseurl_cache:
- text = response.text[0:4096]
+ text = response.text
_baseurl_cache[response] = html.get_base_url(
text, response.url, response.encoding
)
@@ -46,7 +46,7 @@ def get_meta_refresh(
) -> tuple[None, None] | tuple[float, str]:
"""Parse the http-equiv refresh parameter from the given response"""
if response not in _metaref_cache:
- text = response.text[0:4096]
+ text = response.text
_metaref_cache[response] = html.get_meta_refresh(
text, get_base_url(response), response.encoding, ignore_tags=ignore_tags
)
diff --git a/tests/test_utils_response.py b/tests/test_utils_response.py
index 4544cd29e..f79d5ecd4 100644
--- a/tests/test_utils_response.py
+++ b/tests/test_utils_response.py
@@ -321,3 +321,21 @@ def test_open_in_browser_raises_for_unsupported_response_type():
response = Response("http://www.example.com", body=b"binary")
with pytest.raises(TypeError):
open_in_browser(response, _openfunc=lambda _: True)
+
+
+def test_get_base_url_beyond_4096_chars():
+ """get_base_url must find even when it appears after
+ the first 4096 characters of the response body.
+
+ Regression test for https://github.com/scrapy/scrapy/issues/3017
+ """
+ # Build a body where the base tag is past the 4096-char mark by
+ # padding with an HTML comment before the .
+ padding = ""
+ body = (
+ f"{padding}"
+ f''
+ f"content"
+ ).encode()
+ resp = HtmlResponse("http://www.example.com", body=body)
+ assert get_base_url(resp) == "http://www.example.com/img/"