Files
litellm/tests/test_litellm/proxy/_experimental/mcp_server
1b0ae3af83 fix(mcp-oauth): PROXY_BASE_URL escape hatch + diagnostic logging for {"detail":"invalid_request"} (#28086)
* fix(mcp-oauth): add PROXY_BASE_URL escape hatch + diagnostic logging for invalid_request

Customers hitting "{"detail":"invalid_request"}" on the MCP /authorize
endpoint had no way to recover when their ingress mangles X-Forwarded-*
headers (the same-origin check in validate_trusted_redirect_uri compares
the browser-supplied redirect_uri against get_request_base_url, which is
reconstructed from those headers).

Two contained changes:

  1. get_request_base_url now honours PROXY_BASE_URL as the canonical
     public origin when set, bypassing the X-Forwarded-* trust gate
     entirely. Operators who know their public URL can set it once
     instead of debugging ingress header rewrites.

  2. The rejection path in validate_trusted_redirect_uri emits a WARN
     log carrying the redirect_uri, computed proxy base, and the
     X-Forwarded-* / Host headers seen. A bare 400 was undiagnosable;
     this turns it into a one-line root-cause.

* test(mcp-oauth): capture warnings from correct logger ("LiteLLM")

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp-oauth): reject malformed PROXY_BASE_URL with one-shot diagnostic

A scheme-less PROXY_BASE_URL (e.g. "litellm.example.com" instead of
"https://litellm.example.com") would sail through urlparse with empty
scheme + netloc, silently breaking every same-origin compare in
validate_trusted_redirect_uri and leaving the operator staring at the
same opaque 400 the env var was meant to fix.

Validate it once at read time: only honour values that parse as
http(s) URLs with a non-empty netloc; otherwise log a one-shot WARN
naming the bad value and fall through to the request-derived origin
so the proxy still serves traffic.

* fix(mcp/oauth): normalize PROXY_BASE_URL to strip query/fragment

Match the X-Forwarded-* path's normalization so a configured
PROXY_BASE_URL containing a query string or fragment does not break
downstream f-string concatenation like f"{base_url}/callback".

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* refactor(mcp-oauth): drop non-essential comments from PROXY_BASE_URL changes

Strip narrative comments and verbose docstrings added in this PR; the
code is intuitive enough on its own and the log messages already carry
their own diagnostic context. Pre-existing comments are left untouched.

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Yassin Kortam <yassin@berri.ai>
2026-05-16 17:48:03 -07:00
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