Merge pull request #808 from christianlouis/fix/double-slashes-join-url-12822045781097996485

Fix double slashes again

app/utils/network.py

@@ -1,6 +1,7 @@
 import ipaddress
 import logging
 import socket
+from urllib.parse import urlsplit, urlunsplit
 
 logger = logging.getLogger(__name__)
 
@@ -32,3 +33,28 @@ def is_private_ip(hostname: str) -> bool:
             # and SSRF bypasses via unresolvable addresses.
             logger.warning(f"Could not resolve hostname (blocking securely): {hostname}")
             return True
+
+
+def join_url(base: str, *parts: str) -> str:
+    """
+    Safely join a base URL with one or more path parts.
+
+    Uses urllib.parse to correctly handle scheme/netloc/query/fragment so that
+    only the path component is modified.  Leading and trailing slashes are
+    stripped from each part before joining, preventing double-slash sequences
+    at segment boundaries without touching the scheme separator or query string.
+
+    Examples:
+        join_url("https://example.com/dav/", "/remote/", "file.pdf")
+        -> "https://example.com/dav/remote/file.pdf"
+    """
+    parsed = urlsplit(base)
+    # Strip each part once and filter out empty segments; use walrus operator
+    # to avoid calling strip twice per iteration.
+    stripped_parts = [s for p in parts if (s := p.strip("/"))]
+    base_path = parsed.path.rstrip("/")
+    new_path = base_path + "/" + "/".join(stripped_parts) if stripped_parts else base_path
+    # Ensure path is non-empty so the reconstructed URL is valid.
+    if not new_path:
+        new_path = "/"
+    return urlunsplit((parsed.scheme, parsed.netloc, new_path, parsed.query, parsed.fragment))