Mcp support resource discovery (#24223)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/mcp/auth/auth_flow.py

 import secrets
 import urllib.parse
 from typing import Optional
-from urllib.parse import urljoin
+from urllib.parse import urljoin, urlparse
 
 import httpx
 from pydantic import BaseModel, ValidationError
     return full_state_data
 
 
+def check_support_resource_discovery(server_url: str) -> tuple[bool, str]:
+    """Check if the server supports OAuth 2.0 Resource Discovery."""
+    b_scheme, b_netloc, b_path, b_params, b_query, b_fragment = urlparse(server_url, "", True)
+    url_for_resource_discovery = f"{b_scheme}://{b_netloc}/.well-known/oauth-protected-resource{b_path}"
+    if b_query:
+        url_for_resource_discovery += f"?{b_query}"
+    if b_fragment:
+        url_for_resource_discovery += f"#{b_fragment}"
+    try:
+        headers = {"MCP-Protocol-Version": LATEST_PROTOCOL_VERSION, "User-Agent": "Dify"}
+        response = httpx.get(url_for_resource_discovery, headers=headers)
+        if 200 <= response.status_code < 300:
+            body = response.json()
+            if "authorization_server_url" in body:
+                return True, body["authorization_server_url"][0]
+            else:
+                return False, ""
+        return False, ""
+    except httpx.RequestError as e:
+        # Not support resource discovery, fall back to well-known OAuth metadata
+        return False, ""
+
+
 def discover_oauth_metadata(server_url: str, protocol_version: Optional[str] = None) -> Optional[OAuthMetadata]:
     """Looks up RFC 8414 OAuth 2.0 Authorization Server Metadata."""
-    url = urljoin(server_url, "/.well-known/oauth-authorization-server")
+    # First check if the server supports OAuth 2.0 Resource Discovery
+    support_resource_discovery, oauth_discovery_url = check_support_resource_discovery(server_url)
+    if support_resource_discovery:
+        url = oauth_discovery_url
+    else:
+        url = urljoin(server_url, "/.well-known/oauth-authorization-server")
 
     try:
         headers = {"MCP-Protocol-Version": protocol_version or LATEST_PROTOCOL_VERSION}