RFC 8707 Resource Indicators Implementation (#991)

src/mcp/shared/auth_utils.py

@@ -0,0 +1,69 @@
+"""Utilities for OAuth 2.0 Resource Indicators (RFC 8707)."""
+
+from urllib.parse import urlparse, urlsplit, urlunsplit
+
+from pydantic import AnyUrl, HttpUrl
+
+
+def resource_url_from_server_url(url: str | HttpUrl | AnyUrl) -> str:
+    """Convert server URL to canonical resource URL per RFC 8707.
+
+    RFC 8707 section 2 states that resource URIs "MUST NOT include a fragment component".
+    Returns absolute URI with lowercase scheme/host for canonical form.
+
+    Args:
+        url: Server URL to convert
+
+    Returns:
+        Canonical resource URL string
+    """
+    # Convert to string if needed
+    url_str = str(url)
+
+    # Parse the URL and remove fragment, create canonical form
+    parsed = urlsplit(url_str)
+    canonical = urlunsplit(parsed._replace(scheme=parsed.scheme.lower(), netloc=parsed.netloc.lower(), fragment=""))
+
+    return canonical
+
+
+def check_resource_allowed(requested_resource: str, configured_resource: str) -> bool:
+    """Check if a requested resource URL matches a configured resource URL.
+
+    A requested resource matches if it has the same scheme, domain, port,
+    and its path starts with the configured resource's path. This allows
+    hierarchical matching where a token for a parent resource can be used
+    for child resources.
+
+    Args:
+        requested_resource: The resource URL being requested
+        configured_resource: The resource URL that has been configured
+
+    Returns:
+        True if the requested resource matches the configured resource
+    """
+    # Parse both URLs
+    requested = urlparse(requested_resource)
+    configured = urlparse(configured_resource)
+
+    # Compare scheme, host, and port (origin)
+    if requested.scheme.lower() != configured.scheme.lower() or requested.netloc.lower() != configured.netloc.lower():
+        return False
+
+    # Handle cases like requested=/foo and configured=/foo/
+    requested_path = requested.path
+    configured_path = configured.path
+
+    # If requested path is shorter, it cannot be a child
+    if len(requested_path) < len(configured_path):
+        return False
+
+    # Check if the requested path starts with the configured path
+    # Ensure both paths end with / for proper comparison
+    # This ensures that paths like "/api123" don't incorrectly match "/api"
+    if not requested_path.endswith("/"):
+        requested_path += "/"
+    if not configured_path.endswith("/"):
+        configured_path += "/"
+
+    return requested_path.startswith(configured_path)