featurebase/server/tlsconfig.go

// Copyright 2017 Pilosa Corp.
//
// 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.
//
// This file contains source code from bridge
// (https://github.com/robustirc/bridge); which is governed by the following
// license notice:
//
// Copyright © 2014-2015 The RobustIRC Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
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//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
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//       to endorse or promote products derived from this software without
//       specific prior written permission.
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package server

import (
	"crypto/tls"
	"crypto/x509"
	"io/ioutil"
	"log"
	"os"
	"os/signal"
	"sync"
	"syscall"

	"github.com/pkg/errors"
)

type keypairReloader struct {
	certMu   sync.RWMutex
	cert     *tls.Certificate
	certPath string
	keyPath  string
}

func NewKeypairReloader(certPath, keyPath string, logger *log.Logger) (*keypairReloader, error) {
	result := &keypairReloader{
		certPath: certPath,
		keyPath:  keyPath,
	}
	cert, err := tls.LoadX509KeyPair(certPath, keyPath)
	if err != nil {
		return nil, err
	}
	result.cert = &cert
	go func() {
		c := make(chan os.Signal, 1)
		signal.Notify(c, syscall.SIGHUP)
		for range c {
			logger.Printf("Received SIGHUP, reloading TLS certificate and key from %q and %q", certPath, keyPath)
			if err := result.maybeReload(); err != nil {
				logger.Printf("Keeping old TLS certificate because the new one could not be loaded: %v", err)
			}
		}
	}()
	return result, nil
}

func (kpr *keypairReloader) maybeReload() error {
	newCert, err := tls.LoadX509KeyPair(kpr.certPath, kpr.keyPath)
	if err != nil {
		return err
	}
	kpr.certMu.Lock()
	defer kpr.certMu.Unlock()
	kpr.cert = &newCert
	return nil
}

func (kpr *keypairReloader) GetCertificateFunc() func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
	return func(clientHello *tls.ClientHelloInfo) (*tls.Certificate, error) {
		kpr.certMu.RLock()
		defer kpr.certMu.RUnlock()
		return kpr.cert, nil
	}
}

func (kpr *keypairReloader) GetClientCertificateFunc() func(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
	return func(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
		kpr.certMu.RLock()
		defer kpr.certMu.RUnlock()
		return kpr.cert, nil
	}
}

func GetTLSConfig(tlsConfig *TLSConfig, logger *log.Logger) (TLSConfig *tls.Config, err error) {
	if tlsConfig.CertificatePath != "" && tlsConfig.CertificateKeyPath != "" {
		kpr, err := NewKeypairReloader(tlsConfig.CertificatePath, tlsConfig.CertificateKeyPath, logger)
		if err != nil {
			return nil, errors.Wrap(err, "loading keypair")
		}
		TLSConfig = &tls.Config{
			InsecureSkipVerify:       tlsConfig.SkipVerify,
			PreferServerCipherSuites: true,
			MinVersion:               tls.VersionTLS12,
			GetCertificate:           kpr.GetCertificateFunc(),
			GetClientCertificate:     kpr.GetClientCertificateFunc(),
		}
		if tlsConfig.CACertPath != "" {
			b, err := ioutil.ReadFile(tlsConfig.CACertPath)
			if err != nil {
				return nil, errors.Wrap(err, "loading tls ca key")
			}
			certPool := x509.NewCertPool()

			ok := certPool.AppendCertsFromPEM(b)
			if !ok {
				return nil, errors.New("error parsing CA certificate")
			}
			TLSConfig.ClientCAs = certPool
			TLSConfig.RootCAs = certPool
		}
		if tlsConfig.EnableClientVerification {
			TLSConfig.ClientAuth = tls.RequireAndVerifyClientCert
		}
	}
	return TLSConfig, nil
}