fix: resolve relative download redirect URLs

databusclient/api/download.py

@@ -7,7 +7,7 @@
 import re
 import shutil
 import tempfile
-from urllib.parse import urlparse
+from urllib.parse import urljoin, urlparse
 
 import requests
 from SPARQLWrapper import JSON, SPARQLWrapper
@@ -467,7 +467,7 @@ def _download_file(
         307,
         308,
     ]:
-        url = response.headers.get("Location")
+        url = urljoin(url, response.headers["Location"])
         print("Redirects url: ", url)
         # Re-do HEAD request on redirect URL
         response = requests.head(url, timeout=30)

tests/test_download_redirects.py

@@ -0,0 +1,57 @@
+"""Exercise download redirects against a local HTTP server."""
+
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from threading import Thread
+
+import pytest
+
+from databusclient.api.download import _download_file
+
+
+@pytest.mark.parametrize(
+    ("location", "expected_path"),
+    [
+        ("/data.ttl", "/data.ttl"),
+        ("../data.ttl", "/data.ttl"),
+        ("data.ttl", "/entry/data.ttl"),
+        ("{base}/data.ttl", "/data.ttl"),
+        ("//{host}/data.ttl", "/data.ttl"),
+    ],
+)
+def test_download_resolves_redirect_location(tmp_path, location, expected_path):
+    content = b"<urn:s> <urn:p> <urn:o> .\n"
+    requested_paths = []
+
+    class Handler(BaseHTTPRequestHandler):
+        def do_HEAD(self):
+            if self.path == "/entry/file.ttl":
+                self.send_response(302)
+                self.send_header("Location", redirect_location)
+            else:
+                self.send_response(200)
+            self.end_headers()
+
+        def do_GET(self):
+            requested_paths.append(self.path)
+            self.send_response(200)
+            self.send_header("Content-Length", str(len(content)))
+            self.end_headers()
+            self.wfile.write(content)
+
+        def log_message(self, format, *args):
+            pass
+
+    with ThreadingHTTPServer(("127.0.0.1", 0), Handler) as server:
+        host = f"127.0.0.1:{server.server_port}"
+        base = f"http://{host}"
+        redirect_location = location.format(base=base, host=host)
+        thread = Thread(target=server.serve_forever, kwargs={"poll_interval": 0.01})
+        thread.start()
+        try:
+            _download_file(f"{base}/entry/file.ttl", localDir=str(tmp_path))
+        finally:
+            server.shutdown()
+            thread.join()
+
+    assert requested_paths == [expected_path]
+    assert (tmp_path / "file.ttl").read_bytes() == content