chore: Add Transport interface and Toolbox Transport

core/transport/interface.go

@@ -0,0 +1,32 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package transport
+
+import (
+	"context"
+)
+
+type Transport interface {
+	BaseURL() string
+
+	// GetTool fetches a single tool manifest.
+	GetTool(ctx context.Context, toolName string, headers map[string]string) (*ManifestSchema, error)
+
+	// ListTools fetches available tools.
+	ListTools(ctx context.Context, toolsetName string, headers map[string]string) (*ManifestSchema, error)
+
+	// InvokeTool executes a tool.
+	InvokeTool(ctx context.Context, toolName string, payload map[string]any, headers map[string]string) (any, error)
+}

core/transport/toolboxtransport/http.go

@@ -0,0 +1,174 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package toolboxtransport
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/googleapis/mcp-toolbox-sdk-go/core/transport"
+)
+
+type ToolboxTransport struct {
+	baseURL    string
+	httpClient *http.Client
+}
+
+// Ensure that ToolboxTransport implements the Transport interface.
+var _ transport.Transport = &ToolboxTransport{}
+
+func New(baseURL string, client *http.Client) transport.Transport {
+	return &ToolboxTransport{baseURL: baseURL, httpClient: client}
+}
+
+func (t *ToolboxTransport) BaseURL() string { return t.baseURL }
+
+func (t *ToolboxTransport) GetTool(ctx context.Context, toolName string, headers map[string]string) (*transport.ManifestSchema, error) {
+	fullURL, err := url.JoinPath(t.baseURL, "api", "tool", toolName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to construct URL: %w", err)
+	}
+	return t.LoadManifest(ctx, fullURL, headers)
+}
+
+func (t *ToolboxTransport) ListTools(ctx context.Context, toolsetName string, headers map[string]string) (*transport.ManifestSchema, error) {
+	fullURL, err := url.JoinPath(t.baseURL, "api", "toolset", toolsetName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to construct URL: %w", err)
+	}
+	if toolsetName == "" && !strings.HasSuffix(fullURL, "/") {
+		fullURL += "/"
+	}
+	return t.LoadManifest(ctx, fullURL, headers)
+}
+
+// LoadManifest is an internal helper for fetching manifests from the Toolbox server.
+// Inputs:
+//   - ctx: The context to control the lifecycle of the HTTP request, including
+//     cancellation.
+//   - url: The specific URL from which to fetch the manifest.
+//   - headers: A map of token sources to be resolved and applied as
+//     headers to the request.
+//
+// Returns:
+//
+//	A pointer to the successfully parsed ManifestSchema and a nil error, or a
+//	nil ManifestSchema and a descriptive error if any part of the process fails.
+func (t *ToolboxTransport) LoadManifest(ctx context.Context, url string, headers map[string]string) (*transport.ManifestSchema, error) {
+	// Create a new GET request with a context for cancellation.
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create HTTP request : %w", err)
+	}
+
+	// Add all headers to the request
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+
+	//  Execute the HTTP request.
+	resp, err := t.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to make HTTP request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Check for non-successful status codes and include the response body
+	// for better debugging.
+	if resp.StatusCode != http.StatusOK {
+		bodyBytes, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("server returned non-OK status: %d %s, body: %s", resp.StatusCode, resp.Status, string(bodyBytes))
+	}
+
+	// Read the response body.
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	// Unmarshal the JSON body into the ManifestSchema struct.
+	var manifest transport.ManifestSchema
+	if err = json.Unmarshal(body, &manifest); err != nil {
+		return nil, fmt.Errorf("unable to parse manifest correctly: %w", err)
+	}
+	return &manifest, nil
+}
+
+func (t *ToolboxTransport) InvokeTool(ctx context.Context, toolName string, payload map[string]any, headers map[string]string) (any, error) {
+	if !strings.HasPrefix(t.baseURL, "https://") {
+		log.Println("WARNING: Sending ID token over HTTP. User data may be exposed. Use HTTPS for secure communication.")
+	}
+
+	if t.httpClient == nil {
+		return nil, fmt.Errorf("http client is not set for toolbox tool '%s'", toolName)
+	}
+
+	payloadBytes, err := json.Marshal(payload)
+	invocationURL := fmt.Sprintf("%s/api/tool/%s/invoke", t.baseURL, toolName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal tool payload for API call: %w", err)
+	}
+
+	// Assemble the API request
+	req, err := http.NewRequestWithContext(ctx, "POST", invocationURL, bytes.NewBuffer(payloadBytes))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create API request for tool '%s': %w", toolName, err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	// Add all headers to the request
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+
+	// API call execution
+	resp, err := t.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("HTTP call to tool '%s' failed: %w", toolName, err)
+	}
+	defer resp.Body.Close()
+
+	responseBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body for tool '%s': %w", toolName, err)
+	}
+
+	// Handle non-successful status codes
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		var errorResponse map[string]any
+		if jsonErr := json.Unmarshal(responseBody, &errorResponse); jsonErr == nil {
+			if errMsg, ok := errorResponse["error"].(string); ok {
+				return nil, fmt.Errorf("tool '%s' API returned error status %d: %s", toolName, resp.StatusCode, errMsg)
+			}
+		}
+		return nil, fmt.Errorf("tool '%s' API returned unexpected status: %d %s, body: %s", toolName, resp.StatusCode, resp.Status, string(responseBody))
+	}
+
+	// For successful responses, attempt to extract the 'result' field.
+	var apiResult map[string]any
+	if err := json.Unmarshal(responseBody, &apiResult); err == nil {
+		if result, ok := apiResult["result"]; ok {
+			return result, nil
+		}
+	}
+	return string(responseBody), nil
+}