190 lines
4.7 KiB
Go
190 lines
4.7 KiB
Go
/*
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* Minio Cloud Storage, (C) 2018 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package certs
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import (
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"crypto/tls"
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"os"
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"path/filepath"
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"sync"
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"time"
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"github.com/rjeczalik/notify"
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)
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// A Certs represents a certificate manager able to watch certificate
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// and key pairs for changes.
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type Certs struct {
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sync.RWMutex
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// user input params.
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certFile string
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keyFile string
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loadCert LoadX509KeyPairFunc
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// points to the latest certificate.
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cert tls.Certificate
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// internal param to track for events, also
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// used to close the watcher.
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e chan notify.EventInfo
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}
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// LoadX509KeyPairFunc - provides a type for custom cert loader function.
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type LoadX509KeyPairFunc func(certFile, keyFile string) (tls.Certificate, error)
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// New initializes a new certs monitor.
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func New(certFile, keyFile string, loadCert LoadX509KeyPairFunc) (*Certs, error) {
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certFileIsLink, err := checkSymlink(certFile)
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if err != nil {
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return nil, err
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}
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keyFileIsLink, err := checkSymlink(keyFile)
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if err != nil {
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return nil, err
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}
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c := &Certs{
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certFile: certFile,
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keyFile: keyFile,
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loadCert: loadCert,
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// Make the channel buffered to ensure no event is dropped. Notify will drop
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// an event if the receiver is not able to keep up the sending pace.
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e: make(chan notify.EventInfo, 1),
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}
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if certFileIsLink && keyFileIsLink {
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if err := c.watchSymlinks(); err != nil {
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return nil, err
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}
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} else {
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if err := c.watch(); err != nil {
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return nil, err
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}
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}
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return c, nil
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}
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func checkSymlink(file string) (bool, error) {
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st, err := os.Lstat(file)
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if err != nil {
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return false, err
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}
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return st.Mode()&os.ModeSymlink == os.ModeSymlink, nil
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}
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// watchSymlinks reloads symlinked files since fsnotify cannot watch
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// on symbolic links.
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func (c *Certs) watchSymlinks() (err error) {
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c.Lock()
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c.cert, err = c.loadCert(c.certFile, c.keyFile)
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c.Unlock()
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if err != nil {
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return err
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}
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go func() {
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for {
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select {
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case <-c.e:
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// Once stopped exits this routine.
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return
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case <-time.After(24 * time.Hour):
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cert, cerr := c.loadCert(c.certFile, c.keyFile)
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if cerr != nil {
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continue
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}
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c.Lock()
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c.cert = cert
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c.Unlock()
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}
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}
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}()
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return nil
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}
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// watch starts watching for changes to the certificate
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// and key files. On any change the certificate and key
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// are reloaded. If there is an issue the loading will fail
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// and the old (if any) certificates and keys will continue
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// to be used.
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func (c *Certs) watch() (err error) {
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defer func() {
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if err != nil {
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// Stop any watches previously setup after an error.
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notify.Stop(c.e)
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}
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}()
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// Windows doesn't allow for watching file changes but instead allows
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// for directory changes only, while we can still watch for changes
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// on files on other platforms. Watch parent directory on all platforms
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// for simplicity.
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if err = notify.Watch(filepath.Dir(c.certFile), c.e, eventWrite...); err != nil {
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return err
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}
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if err = notify.Watch(filepath.Dir(c.keyFile), c.e, eventWrite...); err != nil {
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return err
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}
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c.Lock()
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c.cert, err = c.loadCert(c.certFile, c.keyFile)
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c.Unlock()
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if err != nil {
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return err
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}
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go c.run()
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return nil
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}
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func (c *Certs) run() {
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for event := range c.e {
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base := filepath.Base(event.Path())
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if isWriteEvent(event.Event()) {
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certChanged := base == filepath.Base(c.certFile)
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keyChanged := base == filepath.Base(c.keyFile)
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if certChanged || keyChanged {
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cert, err := c.loadCert(c.certFile, c.keyFile)
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if err != nil {
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// ignore the error continue to use
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// old certificates.
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continue
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}
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c.Lock()
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c.cert = cert
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c.Unlock()
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}
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}
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}
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}
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// GetCertificateFunc provides a GetCertificate type for custom client implementations.
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type GetCertificateFunc func(hello *tls.ClientHelloInfo) (*tls.Certificate, error)
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// GetCertificate returns the loaded certificate for use by
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// the TLSConfig fields GetCertificate field in a http.Server.
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func (c *Certs) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
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c.RLock()
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defer c.RUnlock()
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return &c.cert, nil
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}
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// Stop tells loader to stop watching for changes to the
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// certificate and key files.
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func (c *Certs) Stop() {
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if c != nil {
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notify.Stop(c.e)
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}
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}
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