/
pemfile_provider.go
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/
pemfile_provider.go
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/*
*
* Copyright 2020 gRPC authors.
*
* 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 advancedtls
import (
"context"
"crypto/tls"
"crypto/x509"
"fmt"
"io/ioutil"
"time"
"google.golang.org/grpc/credentials/tls/certprovider"
"google.golang.org/grpc/grpclog"
)
const defaultIdentityInterval = 1 * time.Hour
const defaultRootInterval = 2 * time.Hour
// readKeyCertPairFunc will be overridden from unit tests.
var readKeyCertPairFunc = tls.LoadX509KeyPair
// readTrustCertFunc will be overridden from unit tests.
var readTrustCertFunc = func(trustFile string) (*x509.CertPool, error) {
trustData, err := ioutil.ReadFile(trustFile)
if err != nil {
return nil, err
}
trustPool := x509.NewCertPool()
if !trustPool.AppendCertsFromPEM(trustData) {
return nil, fmt.Errorf("AppendCertsFromPEM failed to parse certificates")
}
return trustPool, nil
}
var logger = grpclog.Component("advancedtls")
// PEMFileProviderOptions contains options to configure a PEMFileProvider.
// Note that these fields will only take effect during construction. Once the
// PEMFileProvider starts, changing fields in PEMFileProviderOptions will have
// no effect.
type PEMFileProviderOptions struct {
// CertFile is the file path that holds identity certificate whose updates
// will be captured by a watching goroutine.
// Optional. If this is set, KeyFile must also be set.
CertFile string
// KeyFile is the file path that holds identity private key whose updates
// will be captured by a watching goroutine.
// Optional. If this is set, CertFile must also be set.
KeyFile string
// TrustFile is the file path that holds trust certificate whose updates will
// be captured by a watching goroutine.
// Optional.
TrustFile string
// IdentityInterval is the time duration between two credential update checks
// for identity certs.
// Optional. If not set, we will use the default interval(1 hour).
IdentityInterval time.Duration
// RootInterval is the time duration between two credential update checks
// for root certs.
// Optional. If not set, we will use the default interval(2 hours).
RootInterval time.Duration
}
// PEMFileProvider implements certprovider.Provider.
// It provides the most up-to-date identity private key-cert pairs and/or
// root certificates.
type PEMFileProvider struct {
identityDistributor *certprovider.Distributor
rootDistributor *certprovider.Distributor
cancel context.CancelFunc
}
func updateIdentityDistributor(distributor *certprovider.Distributor, certFile, keyFile string) {
if distributor == nil {
return
}
// Read identity certs from PEM files.
identityCert, err := readKeyCertPairFunc(certFile, keyFile)
if err != nil {
// If the reading produces an error, we will skip the update for this
// round and log the error.
logger.Warningf("tls.LoadX509KeyPair reads %s and %s failed: %v", certFile, keyFile, err)
return
}
distributor.Set(&certprovider.KeyMaterial{Certs: []tls.Certificate{identityCert}}, nil)
}
func updateRootDistributor(distributor *certprovider.Distributor, trustFile string) {
if distributor == nil {
return
}
// Read root certs from PEM files.
trustPool, err := readTrustCertFunc(trustFile)
if err != nil {
// If the reading produces an error, we will skip the update for this
// round and log the error.
logger.Warningf("readTrustCertFunc reads %v failed: %v", trustFile, err)
return
}
distributor.Set(&certprovider.KeyMaterial{Roots: trustPool}, nil)
}
// NewPEMFileProvider returns a new PEMFileProvider constructed using the
// provided options.
func NewPEMFileProvider(o PEMFileProviderOptions) (*PEMFileProvider, error) {
if o.CertFile == "" && o.KeyFile == "" && o.TrustFile == "" {
return nil, fmt.Errorf("at least one credential file needs to be specified")
}
if keySpecified, certSpecified := o.KeyFile != "", o.CertFile != ""; keySpecified != certSpecified {
return nil, fmt.Errorf("private key file and identity cert file should be both specified or not specified")
}
if o.IdentityInterval == 0 {
o.IdentityInterval = defaultIdentityInterval
}
if o.RootInterval == 0 {
o.RootInterval = defaultRootInterval
}
provider := &PEMFileProvider{}
if o.CertFile != "" && o.KeyFile != "" {
provider.identityDistributor = certprovider.NewDistributor()
}
if o.TrustFile != "" {
provider.rootDistributor = certprovider.NewDistributor()
}
// A goroutine to pull file changes.
identityTicker := time.NewTicker(o.IdentityInterval)
rootTicker := time.NewTicker(o.RootInterval)
ctx, cancel := context.WithCancel(context.Background())
go func() {
for {
updateIdentityDistributor(provider.identityDistributor, o.CertFile, o.KeyFile)
updateRootDistributor(provider.rootDistributor, o.TrustFile)
select {
case <-ctx.Done():
identityTicker.Stop()
rootTicker.Stop()
return
case <-identityTicker.C:
break
case <-rootTicker.C:
break
}
}
}()
provider.cancel = cancel
return provider, nil
}
// KeyMaterial returns the key material sourced by the PEMFileProvider.
// Callers are expected to use the returned value as read-only.
func (p *PEMFileProvider) KeyMaterial(ctx context.Context) (*certprovider.KeyMaterial, error) {
km := &certprovider.KeyMaterial{}
if p.identityDistributor != nil {
identityKM, err := p.identityDistributor.KeyMaterial(ctx)
if err != nil {
return nil, err
}
km.Certs = identityKM.Certs
}
if p.rootDistributor != nil {
rootKM, err := p.rootDistributor.KeyMaterial(ctx)
if err != nil {
return nil, err
}
km.Roots = rootKM.Roots
}
return km, nil
}
// Close cleans up resources allocated by the PEMFileProvider.
func (p *PEMFileProvider) Close() {
p.cancel()
if p.identityDistributor != nil {
p.identityDistributor.Stop()
}
if p.rootDistributor != nil {
p.rootDistributor.Stop()
}
}