Documentation
¶
Overview ¶
Package mcp is part of the GoFastr framework. See https://github.com/DonaldMurillo/gofastr for documentation.
Package mcp implements a Model Context Protocol server for GoFastr.
It provides tool registration, JSON-RPC 2.0 message handling, and transports for stdio and HTTP/SSE.
Index ¶
- Constants
- func RequestFromContext(ctx context.Context) (*http.Request, bool)
- func StreamSSE(w io.Writer, event, data string)
- func WithRequest(ctx context.Context, r *http.Request) context.Context
- type RPCError
- type Request
- type Response
- type Server
- func (s *Server) CallTool(ctx context.Context, name string, params map[string]any) (any, error)
- func (s *Server) HandleRequest(ctx context.Context, req Request) Response
- func (s *Server) ListTools() []Tool
- func (s *Server) RegisterTool(name, description string, inputSchema map[string]any, fn ToolHandler) error
- func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request)
- func (s *Server) ServeSSE(path string) http.Handler
- func (s *Server) ServeStdio(ctx context.Context, in io.Reader, out io.Writer) error
- type Tool
- type ToolHandler
Constants ¶
const ( ErrMethodNotFound = -32601 ErrInvalidParams = -32602 ErrInternalError = -32603 )
JSON-RPC 2.0 standard error codes.
Variables ¶
This section is empty.
Functions ¶
func RequestFromContext ¶
RequestFromContext returns the original inbound *http.Request stashed by the transport, if any. Tool handlers that re-dispatch through an HTTP router use it to copy the caller's auth onto the internal request so session/JWT middleware re-resolves the same user instead of demoting to anonymous.
func StreamSSE ¶
StreamSSE writes a single SSE event to the writer. It is the hardened entry point for tool-result streaming and treats both arguments as untrusted:
- the event name is truncated at the first CR/LF/NUL so the caller can't terminate the "event:" field and inject a forged directive below it.
- data is collapsed to a single line (CR/LF/NUL stripped) and any occurrence of a literal SSE directive marker (e.g. "event:", "id:", "retry:", "data:") inside the payload has its colon replaced with " -" so the bytes can no longer be mistaken for — or substring-matched as — an injected directive.
func WithRequest ¶
WithRequest stashes the original inbound *http.Request in ctx so tool handlers can recover the caller's transport-level auth (Cookie / Authorization headers). The HTTP transports call this automatically; it is exported so non-HTTP callers (and tests) can populate the same slot.
Types ¶
type RPCError ¶
type RPCError struct {
Code int `json:"code"`
Message string `json:"message"`
Data any `json:"data,omitempty"`
}
RPCError represents a JSON-RPC 2.0 error object.
type Request ¶
type Request struct {
JSONRPC string `json:"jsonrpc"`
ID any `json:"id"`
Method string `json:"method"`
Params json.RawMessage `json:"params,omitempty"`
}
Request represents a JSON-RPC 2.0 request.
type Response ¶
type Response struct {
JSONRPC string `json:"jsonrpc"`
ID any `json:"id"`
Result any `json:"result,omitempty"`
Error *RPCError `json:"error,omitempty"`
}
Response represents a JSON-RPC 2.0 response.
type Server ¶
type Server struct {
// contains filtered or unexported fields
}
Server is an MCP server with a tool registry.
func NewServer ¶
func NewServer() *Server
NewServer creates a new MCP server with an empty tool registry.
func (*Server) CallTool ¶
CallTool is the exported form of callTool: invokes a registered tool by name with the given params. Use this when calling MCP tools in-process (tests, server-side integrations) without going through the JSON-RPC transport layer.
func (*Server) HandleRequest ¶
HandleRequest routes a JSON-RPC 2.0 request to the correct handler and returns the appropriate response.
func (*Server) ListTools ¶
ListTools returns all registered tools (handlers are nilled out for safety). This is the exported version of listTools for external consumption.
func (*Server) RegisterTool ¶
func (s *Server) RegisterTool(name, description string, inputSchema map[string]any, fn ToolHandler) error
RegisterTool adds a tool to the server's registry. Returns an error if a tool with the same name already exists.
func (*Server) ServeHTTP ¶
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request)
ServeHTTP handles HTTP POST requests for MCP JSON-RPC calls. It reads a JSON-RPC request from the body and writes the response.
Source Files