urllib3 does not control redirects in browsers and Node.js

@@ -4,6 +4,8 @@
 - Fixed a security issue where restricting the maximum number of followed
   redirects at the ``urllib3.PoolManager`` level via the ``retries`` parameter
   did not work.
+- Made the Node.js runtime respect redirect parameters such as ``retries``
+  and ``redirects``.
 - TODO: add other entries in the release PR.
 
 

@@ -65,7 +65,7 @@ Features which are usable with Emscripten support are:
 * Timeouts
 * Retries
 * Streaming (with Web Workers and Cross-Origin Isolation)
-* Redirects (determined by browser/runtime, not restrictable with urllib3)
+* Redirects (urllib3 controls redirects in Node.js but not in browsers where behavior is determined by runtime)
 * Decompressing response bodies
 
 Features which don't work with Emscripten:

@@ -573,6 +573,11 @@ def send_jspi_request(
         "method": request.method,
         "signal": js_abort_controller.signal,
     }
+    # Node.js returns the whole response (unlike opaqueredirect in browsers),
+    # so urllib3 can set `redirect: manual` to control redirects itself.
+    # https://stackoverflow.com/a/78524615
+    if _is_node_js():
+        fetch_data["redirect"] = "manual"
     # Call JavaScript fetch (async api, returns a promise)
     fetcher_promise_js = js.fetch(request.url, _obj_from_dict(fetch_data))
     # Now suspend WebAssembly until we resolve that promise
@@ -693,6 +698,21 @@ def has_jspi() -> bool:
         return False
 
 
+def _is_node_js() -> bool:
+    """
+    Check if we are in Node.js.
+
+    :return: True if we are in Node.js.
+    :rtype: bool
+    """
+    return (
+        hasattr(js, "process")
+        and hasattr(js.process, "release")
+        # According to the Node.js documentation, the release name is always "node".
+        and js.process.release.name == "node"
+    )
+
+
 def streaming_ready() -> bool | None:
     if _fetcher:
         return _fetcher.streaming_ready

@@ -960,6 +960,52 @@ def pyodide_test(selenium_coverage: typing.Any, host: str, port: int) -> None:
     )
 
 
+@pytest.mark.with_jspi
+def test_disabled_redirects(
+    selenium_coverage: typing.Any, testserver_http: PyodideServerInfo
+) -> None:
+    """
+    Test that urllib3 can control redirects in Node.js.
+    """
+
+    @run_in_pyodide  # type: ignore[misc]
+    def pyodide_test(selenium_coverage: typing.Any, host: str, port: int) -> None:
+        import pytest
+
+        from urllib3 import PoolManager, request
+        from urllib3.contrib.emscripten.fetch import _is_node_js
+        from urllib3.exceptions import MaxRetryError
+
+        if not _is_node_js():
+            pytest.skip("urllib3 does not control redirects in browsers.")
+
+        redirect_url = f"http://{host}:{port}/redirect"
+
+        with PoolManager(retries=0) as http:
+            with pytest.raises(MaxRetryError):
+                http.request("GET", redirect_url)
+
+            response = http.request("GET", redirect_url, redirect=False)
+            assert response.status == 303
+
+        with PoolManager(retries=False) as http:
+            response = http.request("GET", redirect_url)
+            assert response.status == 303
+
+        with pytest.raises(MaxRetryError):
+            request("GET", redirect_url, retries=0)
+
+        response = request("GET", redirect_url, redirect=False)
+        assert response.status == 303
+
+        response = request("GET", redirect_url, retries=0, redirect=False)
+        assert response.status == 303
+
+    pyodide_test(
+        selenium_coverage, testserver_http.http_host, testserver_http.http_port
+    )
+
+
 def test_insecure_requests_warning(
     selenium_coverage: typing.Any, testserver_http: PyodideServerInfo
 ) -> None: