feat: HTTP Header Standardization for method and name

mcp/mcp_http_headers.go

@@ -0,0 +1,93 @@
+// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by the license
+// that can be found in the LICENSE file.
+
+package mcp
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/modelcontextprotocol/go-sdk/jsonrpc"
+)
+
+const (
+	ProtocolVersionHeader        = "Mcp-Protocol-Version"
+	SessionIDHeader              = "Mcp-Session-Id"
+	LastEventIDHeader            = "Last-Event-ID"
+	MethodHeader                 = "Mcp-Method"
+	NameHeader                   = "Mcp-Name"
+	MinVersionForStandardHeaders = "2026-06-XX"
+)
+
+func extractName(method string, params json.RawMessage) (string, bool) {
+	switch method {
+	case "tools/call":
+		var p CallToolParams
+		if err := json.Unmarshal(params, &p); err == nil {
+			return p.Name, true
+		}
+	case "prompts/get":
+		var p GetPromptParams
+		if err := json.Unmarshal(params, &p); err == nil {
+			return p.Name, true
+		}
+	case "resources/read":
+		var p ReadResourceParams
+		if err := json.Unmarshal(params, &p); err == nil {
+			return p.URI, true
+		}
+	}
+
+	return "", false
+}
+
+func setStandardHeaders(header http.Header, msg jsonrpc.Message) {
+	if msg == nil {
+		return
+	}
+	if header.Get(ProtocolVersionHeader) == "" || header.Get(ProtocolVersionHeader) < MinVersionForStandardHeaders {
+		return
+	}
+
+	switch msg := msg.(type) {
+	case *jsonrpc.Request:
+		header.Set(MethodHeader, msg.Method)
+		if name, ok := extractName(msg.Method, msg.Params); ok {
+			header.Set(NameHeader, name)
+		}
+	}
+}
+
+func validateMcpHeaders(header http.Header, msg jsonrpc.Message) error {
+	protocolVersion := header.Get(ProtocolVersionHeader)
+	if protocolVersion == "" || protocolVersion < MinVersionForStandardHeaders {
+		return nil
+	}
+
+	switch msg := msg.(type) {
+	case *jsonrpc.Request:
+		methodInHeader := header.Get(MethodHeader)
+		if methodInHeader == "" {
+			return errors.New("missing required Mcp-Method header")
+		}
+		if methodInHeader != msg.Method {
+			return fmt.Errorf("header mismatch: Mcp-Method header value '%s' does not match body value '%s'", methodInHeader, msg.Method)
+		}
+
+		if msg.Method == "tools/call" || msg.Method == "resources/read" || msg.Method == "prompts/get" {
+			nameInHeader := header.Get(NameHeader)
+			if nameInHeader == "" {
+				return fmt.Errorf("missing required Mcp-Name header for method %q", msg.Method)
+			}
+			if nameInBody, ok := extractName(msg.Method, msg.Params); ok {
+				if nameInHeader != nameInBody {
+					return fmt.Errorf("header mismatch: Mcp-Name header value '%s' does not match body value '%s'", nameInHeader, nameInBody)
+				}
+			}
+		}
+	}
+	return nil
+}