chore: migrate to gitea

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

@@ -0,0 +1,361 @@
+// 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"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"log"
+	"log/slog"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+
+	"cloud.google.com/go/auth/internal"
+	"cloud.google.com/go/auth/internal/transport/cert"
+	"github.com/google/s2a-go"
+	"google.golang.org/grpc/credentials"
+)
+
+const (
+	mTLSModeAlways = "always"
+	mTLSModeNever  = "never"
+	mTLSModeAuto   = "auto"
+
+	// Experimental: if true, the code will try MTLS with S2A as the default for transport security. Default value is false.
+	googleAPIUseS2AEnv     = "EXPERIMENTAL_GOOGLE_API_USE_S2A"
+	googleAPIUseCertSource = "GOOGLE_API_USE_CLIENT_CERTIFICATE"
+	googleAPIUseMTLS       = "GOOGLE_API_USE_MTLS_ENDPOINT"
+	googleAPIUseMTLSOld    = "GOOGLE_API_USE_MTLS"
+
+	universeDomainPlaceholder = "UNIVERSE_DOMAIN"
+
+	mtlsMDSRoot = "/run/google-mds-mtls/root.crt"
+	mtlsMDSKey  = "/run/google-mds-mtls/client.key"
+)
+
+// Type represents the type of transport used.
+type Type int
+
+const (
+	// TransportTypeUnknown represents an unknown transport type and is the default option.
+	TransportTypeUnknown Type = iota
+	// TransportTypeMTLSS2A represents the mTLS transport type using S2A.
+	TransportTypeMTLSS2A
+)
+
+// Options is a struct that is duplicated information from the individual
+// transport packages in order to avoid cyclic deps. It correlates 1:1 with
+// fields on httptransport.Options and grpctransport.Options.
+type Options struct {
+	Endpoint                string
+	DefaultEndpointTemplate string
+	DefaultMTLSEndpoint     string
+	ClientCertProvider      cert.Provider
+	Client                  *http.Client
+	UniverseDomain          string
+	EnableDirectPath        bool
+	EnableDirectPathXds     bool
+	Logger                  *slog.Logger
+}
+
+// getUniverseDomain returns the default service domain for a given Cloud
+// universe.
+func (o *Options) getUniverseDomain() string {
+	if o.UniverseDomain == "" {
+		return internal.DefaultUniverseDomain
+	}
+	return o.UniverseDomain
+}
+
+// isUniverseDomainGDU returns true if the universe domain is the default Google
+// universe.
+func (o *Options) isUniverseDomainGDU() bool {
+	return o.getUniverseDomain() == internal.DefaultUniverseDomain
+}
+
+// defaultEndpoint returns the DefaultEndpointTemplate merged with the
+// universe domain if the DefaultEndpointTemplate is set, otherwise returns an
+// empty string.
+func (o *Options) defaultEndpoint() string {
+	if o.DefaultEndpointTemplate == "" {
+		return ""
+	}
+	return strings.Replace(o.DefaultEndpointTemplate, universeDomainPlaceholder, o.getUniverseDomain(), 1)
+}
+
+// defaultMTLSEndpoint returns the DefaultMTLSEndpointTemplate merged with the
+// universe domain if the DefaultMTLSEndpointTemplate is set, otherwise returns an
+// empty string.
+func (o *Options) defaultMTLSEndpoint() string {
+	if o.DefaultMTLSEndpoint == "" {
+		return ""
+	}
+	return strings.Replace(o.DefaultMTLSEndpoint, universeDomainPlaceholder, o.getUniverseDomain(), 1)
+}
+
+// mergedEndpoint merges a user-provided Endpoint of format host[:port] with the
+// default endpoint.
+func (o *Options) mergedEndpoint() (string, error) {
+	defaultEndpoint := o.defaultEndpoint()
+	u, err := url.Parse(fixScheme(defaultEndpoint))
+	if err != nil {
+		return "", err
+	}
+	return strings.Replace(defaultEndpoint, u.Host, o.Endpoint, 1), nil
+}
+
+func fixScheme(baseURL string) string {
+	if !strings.Contains(baseURL, "://") {
+		baseURL = "https://" + baseURL
+	}
+	return baseURL
+}
+
+// GRPCTransportCredentials embeds interface TransportCredentials with additional data.
+type GRPCTransportCredentials struct {
+	credentials.TransportCredentials
+	Endpoint      string
+	TransportType Type
+}
+
+// GetGRPCTransportCredsAndEndpoint returns an instance of
+// [google.golang.org/grpc/credentials.TransportCredentials], and the
+// corresponding endpoint and transport type to use for GRPC client.
+func GetGRPCTransportCredsAndEndpoint(opts *Options) (*GRPCTransportCredentials, error) {
+	config, err := getTransportConfig(opts)
+	if err != nil {
+		return nil, err
+	}
+
+	defaultTransportCreds := credentials.NewTLS(&tls.Config{
+		GetClientCertificate: config.clientCertSource,
+	})
+
+	var s2aAddr string
+	var transportCredsForS2A credentials.TransportCredentials
+
+	if config.mtlsS2AAddress != "" {
+		s2aAddr = config.mtlsS2AAddress
+		transportCredsForS2A, err = loadMTLSMDSTransportCreds(mtlsMDSRoot, mtlsMDSKey)
+		if err != nil {
+			log.Printf("Loading MTLS MDS credentials failed: %v", err)
+			if config.s2aAddress != "" {
+				s2aAddr = config.s2aAddress
+			} else {
+				return &GRPCTransportCredentials{defaultTransportCreds, config.endpoint, TransportTypeUnknown}, nil
+			}
+		}
+	} else if config.s2aAddress != "" {
+		s2aAddr = config.s2aAddress
+	} else {
+		return &GRPCTransportCredentials{defaultTransportCreds, config.endpoint, TransportTypeUnknown}, nil
+	}
+
+	s2aTransportCreds, err := s2a.NewClientCreds(&s2a.ClientOptions{
+		S2AAddress:     s2aAddr,
+		TransportCreds: transportCredsForS2A,
+	})
+	if err != nil {
+		// Use default if we cannot initialize S2A client transport credentials.
+		return &GRPCTransportCredentials{defaultTransportCreds, config.endpoint, TransportTypeUnknown}, nil
+	}
+	return &GRPCTransportCredentials{s2aTransportCreds, config.s2aMTLSEndpoint, TransportTypeMTLSS2A}, nil
+}
+
+// GetHTTPTransportConfig returns a client certificate source and a function for
+// dialing MTLS with S2A.
+func GetHTTPTransportConfig(opts *Options) (cert.Provider, func(context.Context, string, string) (net.Conn, error), error) {
+	config, err := getTransportConfig(opts)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var s2aAddr string
+	var transportCredsForS2A credentials.TransportCredentials
+
+	if config.mtlsS2AAddress != "" {
+		s2aAddr = config.mtlsS2AAddress
+		transportCredsForS2A, err = loadMTLSMDSTransportCreds(mtlsMDSRoot, mtlsMDSKey)
+		if err != nil {
+			log.Printf("Loading MTLS MDS credentials failed: %v", err)
+			if config.s2aAddress != "" {
+				s2aAddr = config.s2aAddress
+			} else {
+				return config.clientCertSource, nil, nil
+			}
+		}
+	} else if config.s2aAddress != "" {
+		s2aAddr = config.s2aAddress
+	} else {
+		return config.clientCertSource, nil, nil
+	}
+
+	dialTLSContextFunc := s2a.NewS2ADialTLSContextFunc(&s2a.ClientOptions{
+		S2AAddress:     s2aAddr,
+		TransportCreds: transportCredsForS2A,
+	})
+	return nil, dialTLSContextFunc, nil
+}
+
+func loadMTLSMDSTransportCreds(mtlsMDSRootFile, mtlsMDSKeyFile string) (credentials.TransportCredentials, error) {
+	rootPEM, err := os.ReadFile(mtlsMDSRootFile)
+	if err != nil {
+		return nil, err
+	}
+	caCertPool := x509.NewCertPool()
+	ok := caCertPool.AppendCertsFromPEM(rootPEM)
+	if !ok {
+		return nil, errors.New("failed to load MTLS MDS root certificate")
+	}
+	// The mTLS MDS credentials are formatted as the concatenation of a PEM-encoded certificate chain
+	// followed by a PEM-encoded private key. For this reason, the concatenation is passed in to the
+	// tls.X509KeyPair function as both the certificate chain and private key arguments.
+	cert, err := tls.LoadX509KeyPair(mtlsMDSKeyFile, mtlsMDSKeyFile)
+	if err != nil {
+		return nil, err
+	}
+	tlsConfig := tls.Config{
+		RootCAs:      caCertPool,
+		Certificates: []tls.Certificate{cert},
+		MinVersion:   tls.VersionTLS13,
+	}
+	return credentials.NewTLS(&tlsConfig), nil
+}
+
+func getTransportConfig(opts *Options) (*transportConfig, error) {
+	clientCertSource, err := GetClientCertificateProvider(opts)
+	if err != nil {
+		return nil, err
+	}
+	endpoint, err := getEndpoint(opts, clientCertSource)
+	if err != nil {
+		return nil, err
+	}
+	defaultTransportConfig := transportConfig{
+		clientCertSource: clientCertSource,
+		endpoint:         endpoint,
+	}
+
+	if !shouldUseS2A(clientCertSource, opts) {
+		return &defaultTransportConfig, nil
+	}
+
+	s2aAddress := GetS2AAddress(opts.Logger)
+	mtlsS2AAddress := GetMTLSS2AAddress(opts.Logger)
+	if s2aAddress == "" && mtlsS2AAddress == "" {
+		return &defaultTransportConfig, nil
+	}
+	return &transportConfig{
+		clientCertSource: clientCertSource,
+		endpoint:         endpoint,
+		s2aAddress:       s2aAddress,
+		mtlsS2AAddress:   mtlsS2AAddress,
+		s2aMTLSEndpoint:  opts.defaultMTLSEndpoint(),
+	}, nil
+}
+
+// GetClientCertificateProvider returns a default client certificate source, if
+// not provided by the user.
+//
+// A nil default source can be returned if the source does not exist. Any exceptions
+// encountered while initializing the default source will be reported as client
+// error (ex. corrupt metadata file).
+func GetClientCertificateProvider(opts *Options) (cert.Provider, error) {
+	if !isClientCertificateEnabled(opts) {
+		return nil, nil
+	} else if opts.ClientCertProvider != nil {
+		return opts.ClientCertProvider, nil
+	}
+	return cert.DefaultProvider()
+
+}
+
+// isClientCertificateEnabled returns true by default for all GDU universe domain, unless explicitly overridden by env var
+func isClientCertificateEnabled(opts *Options) bool {
+	if value, ok := os.LookupEnv(googleAPIUseCertSource); ok {
+		// error as false is OK
+		b, _ := strconv.ParseBool(value)
+		return b
+	}
+	return opts.isUniverseDomainGDU()
+}
+
+type transportConfig struct {
+	// The client certificate source.
+	clientCertSource cert.Provider
+	// The corresponding endpoint to use based on client certificate source.
+	endpoint string
+	// The plaintext S2A address if it can be used, otherwise an empty string.
+	s2aAddress string
+	// The MTLS S2A address if it can be used, otherwise an empty string.
+	mtlsS2AAddress string
+	// The MTLS endpoint to use with S2A.
+	s2aMTLSEndpoint string
+}
+
+// getEndpoint returns the endpoint for the service, taking into account the
+// user-provided endpoint override "settings.Endpoint".
+//
+// If no endpoint override is specified, we will either return the default
+// endpoint or the default mTLS endpoint if a client certificate is available.
+//
+// You can override the default endpoint choice (mTLS vs. regular) by setting
+// the GOOGLE_API_USE_MTLS_ENDPOINT environment variable.
+//
+// If the endpoint override is an address (host:port) rather than full base
+// URL (ex. https://...), then the user-provided address will be merged into
+// the default endpoint. For example, WithEndpoint("myhost:8000") and
+// DefaultEndpointTemplate("https://UNIVERSE_DOMAIN/bar/baz") will return
+// "https://myhost:8080/bar/baz". Note that this does not apply to the mTLS
+// endpoint.
+func getEndpoint(opts *Options, clientCertSource cert.Provider) (string, error) {
+	if opts.Endpoint == "" {
+		mtlsMode := getMTLSMode()
+		if mtlsMode == mTLSModeAlways || (clientCertSource != nil && mtlsMode == mTLSModeAuto) {
+			return opts.defaultMTLSEndpoint(), nil
+		}
+		return opts.defaultEndpoint(), nil
+	}
+	if strings.Contains(opts.Endpoint, "://") {
+		// User passed in a full URL path, use it verbatim.
+		return opts.Endpoint, nil
+	}
+	if opts.defaultEndpoint() == "" {
+		// If DefaultEndpointTemplate is not configured,
+		// use the user provided endpoint verbatim. This allows a naked
+		// "host[:port]" URL to be used with GRPC Direct Path.
+		return opts.Endpoint, nil
+	}
+
+	// Assume user-provided endpoint is host[:port], merge it with the default endpoint.
+	return opts.mergedEndpoint()
+}
+
+func getMTLSMode() string {
+	mode := os.Getenv(googleAPIUseMTLS)
+	if mode == "" {
+		mode = os.Getenv(googleAPIUseMTLSOld) // Deprecated.
+	}
+	if mode == "" {
+		return mTLSModeAuto
+	}
+	return strings.ToLower(mode)
+}