feat(auth): add token_endpoint_auth_method to OAuthClientConfig#1
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feat(auth): add token_endpoint_auth_method to OAuthClientConfig#1
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Some OAuth providers (e.g. HubSpot) require client credentials to be sent as POST body parameters (client_secret_post) instead of via HTTP Basic Auth header. The oauth2 crate defaults to BasicAuth, and rmcp had no way to override this, causing TokenExchangeFailed errors. Add an optional `token_endpoint_auth_method` field to OAuthClientConfig that accepts "client_secret_post" (RequestBody) and "client_secret_basic" (BasicAuth). Unknown values are silently ignored, preserving the default. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Move auth method selection from per-client config to server's AuthorizationMetadata, which is the correct OAuth 2.0 approach. Servers like HubSpot advertise token_endpoint_auth_methods_supported in their metadata; reading it from there avoids manual configuration and prevents TokenExchangeFailed errors with non-BasicAuth providers. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…ional_fields Move token_endpoint_auth_methods_supported out of AuthorizationMetadata as an explicit field and read it from the serde(flatten) additional_fields HashMap instead. This avoids serializing `null` when the field is absent, which broke Zod validation in downstream consumers like MCP Inspector. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
… test assertions When token_endpoint_auth_methods_supported contains both client_secret_post and client_secret_basic, default to basic auth per RFC 6749 §2.3.1. Update configure_client tests to assert actual AuthType instead of is_some(). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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This pr was merged to the original repo here: modelcontextprotocol#648 |
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Summary
token_endpoint_auth_method: Option<String>toOAuthClientConfigso callers can choose betweenclient_secret_post(POST body) andclient_secret_basic(HTTP Basic Auth, the default)TokenExchangeFailederrors with OAuth providers like HubSpot that require credentials in the POST bodyTest plan
client_secret_post,client_secret_basic,None, and unknown method valuescargo clippy -p rmcp --features auth -- -D warningspasses clean🤖 Generated with Claude Code