chore: migrate to gitea

vendor/cloud.google.com/go/auth/internal/transport/s2a.go

@@ -0,0 +1,138 @@
+// Copyright 2023 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"
+	"encoding/json"
+	"fmt"
+	"log"
+	"log/slog"
+	"os"
+	"strconv"
+	"sync"
+
+	"cloud.google.com/go/auth/internal/transport/cert"
+	"cloud.google.com/go/compute/metadata"
+)
+
+const (
+	configEndpointSuffix = "instance/platform-security/auto-mtls-configuration"
+)
+
+var (
+	mtlsConfiguration *mtlsConfig
+
+	mtlsOnce sync.Once
+)
+
+// GetS2AAddress returns the S2A address to be reached via plaintext connection.
+// Returns empty string if not set or invalid.
+func GetS2AAddress(logger *slog.Logger) string {
+	getMetadataMTLSAutoConfig(logger)
+	if !mtlsConfiguration.valid() {
+		return ""
+	}
+	return mtlsConfiguration.S2A.PlaintextAddress
+}
+
+// GetMTLSS2AAddress returns the S2A address to be reached via MTLS connection.
+// Returns empty string if not set or invalid.
+func GetMTLSS2AAddress(logger *slog.Logger) string {
+	getMetadataMTLSAutoConfig(logger)
+	if !mtlsConfiguration.valid() {
+		return ""
+	}
+	return mtlsConfiguration.S2A.MTLSAddress
+}
+
+// mtlsConfig contains the configuration for establishing MTLS connections with Google APIs.
+type mtlsConfig struct {
+	S2A *s2aAddresses `json:"s2a"`
+}
+
+func (c *mtlsConfig) valid() bool {
+	return c != nil && c.S2A != nil
+}
+
+// s2aAddresses contains the plaintext and/or MTLS S2A addresses.
+type s2aAddresses struct {
+	// PlaintextAddress is the plaintext address to reach S2A
+	PlaintextAddress string `json:"plaintext_address"`
+	// MTLSAddress is the MTLS address to reach S2A
+	MTLSAddress string `json:"mtls_address"`
+}
+
+func getMetadataMTLSAutoConfig(logger *slog.Logger) {
+	var err error
+	mtlsOnce.Do(func() {
+		mtlsConfiguration, err = queryConfig(logger)
+		if err != nil {
+			log.Printf("Getting MTLS config failed: %v", err)
+		}
+	})
+}
+
+var httpGetMetadataMTLSConfig = func(logger *slog.Logger) (string, error) {
+	metadataClient := metadata.NewWithOptions(&metadata.Options{
+		Logger: logger,
+	})
+	return metadataClient.GetWithContext(context.Background(), configEndpointSuffix)
+}
+
+func queryConfig(logger *slog.Logger) (*mtlsConfig, error) {
+	resp, err := httpGetMetadataMTLSConfig(logger)
+	if err != nil {
+		return nil, fmt.Errorf("querying MTLS config from MDS endpoint failed: %w", err)
+	}
+	var config mtlsConfig
+	err = json.Unmarshal([]byte(resp), &config)
+	if err != nil {
+		return nil, fmt.Errorf("unmarshalling MTLS config from MDS endpoint failed: %w", err)
+	}
+	if config.S2A == nil {
+		return nil, fmt.Errorf("returned MTLS config from MDS endpoint is invalid: %v", config)
+	}
+	return &config, nil
+}
+
+func shouldUseS2A(clientCertSource cert.Provider, opts *Options) bool {
+	// If client cert is found, use that over S2A.
+	if clientCertSource != nil {
+		return false
+	}
+	// If EXPERIMENTAL_GOOGLE_API_USE_S2A is not set to true, skip S2A.
+	if !isGoogleS2AEnabled() {
+		return false
+	}
+	// If DefaultMTLSEndpoint is not set or has endpoint override, skip S2A.
+	if opts.DefaultMTLSEndpoint == "" || opts.Endpoint != "" {
+		return false
+	}
+	// If custom HTTP client is provided, skip S2A.
+	if opts.Client != nil {
+		return false
+	}
+	// If directPath is enabled, skip S2A.
+	return !opts.EnableDirectPath && !opts.EnableDirectPathXds
+}
+
+func isGoogleS2AEnabled() bool {
+	b, err := strconv.ParseBool(os.Getenv(googleAPIUseS2AEnv))
+	if err != nil {
+		return false
+	}
+	return b
+}