forked from TrueCloudLab/certificates
136 lines
2.9 KiB
Go
136 lines
2.9 KiB
Go
package main
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import (
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"crypto/tls"
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"crypto/x509"
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"errors"
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"fmt"
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"io/ioutil"
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"log"
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"net/http"
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"sync"
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"time"
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)
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const (
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autocertFile = "/var/run/autocert.step.sm/site.crt"
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autocertKey = "/var/run/autocert.step.sm/site.key"
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autocertRoot = "/var/run/autocert.step.sm/root.crt"
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tickFrequency = 15 * time.Second
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)
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// Uses techniques from https://diogomonica.com/2017/01/11/hitless-tls-certificate-rotation-in-go/
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// to automatically rotate certificates when they're renewed.
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type rotator struct {
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sync.Mutex
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certificate *tls.Certificate
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}
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func (r *rotator) getCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
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r.Lock()
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defer r.Unlock()
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return r.certificate, nil
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}
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func (r *rotator) loadCertificate(certFile, keyFile string) error {
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r.Lock()
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defer r.Unlock()
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c, err := tls.LoadX509KeyPair(certFile, keyFile)
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if err != nil {
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return err
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}
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r.certificate = &c
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return nil
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}
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func loadRootCertPool() (*x509.CertPool, error) {
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root, err := ioutil.ReadFile(autocertRoot)
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if err != nil {
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return nil, err
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}
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pool := x509.NewCertPool()
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if ok := pool.AppendCertsFromPEM(root); !ok {
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return nil, errors.New("Missing or invalid root certificate")
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}
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return pool, nil
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}
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func main() {
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mux := http.NewServeMux()
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mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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if r.TLS == nil || len(r.TLS.PeerCertificates) == 0 {
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fmt.Fprintf(w, "Unauthenticated")
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} else {
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name := r.TLS.PeerCertificates[0].Subject.CommonName
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fmt.Fprintf(w, "Hello, %s!\n", name)
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}
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})
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mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
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fmt.Fprintf(w, "Ok\n")
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})
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roots, err := loadRootCertPool()
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if err != nil {
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log.Fatal(err)
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}
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r := &rotator{}
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cfg := &tls.Config{
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ClientAuth: tls.RequireAndVerifyClientCert,
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ClientCAs: roots,
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MinVersion: tls.VersionTLS12,
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CurvePreferences: []tls.CurveID{tls.CurveP521, tls.CurveP384, tls.CurveP256},
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PreferServerCipherSuites: true,
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CipherSuites: []uint16{
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tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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},
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GetCertificate: r.getCertificate,
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}
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srv := &http.Server{
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Addr: ":443",
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Handler: mux,
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TLSConfig: cfg,
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}
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// Load certificate
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err = r.loadCertificate(autocertFile, autocertKey)
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if err != nil {
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log.Fatal("Error loading certificate and key", err)
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}
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// Schedule periodic re-load of certificate
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done := make(chan struct{})
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go func() {
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ticker := time.NewTicker(tickFrequency)
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defer ticker.Stop()
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for {
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select {
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case <-ticker.C:
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fmt.Println("Checking for new certificate...")
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err := r.loadCertificate(autocertFile, autocertKey)
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if err != nil {
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log.Println("Error loading certificate and key", err)
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}
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case <-done:
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return
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}
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}
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}()
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defer close(done)
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log.Println("Listening no :443")
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// Start serving HTTPS
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err = srv.ListenAndServeTLS("", "")
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if err != nil {
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log.Fatal("ListenAndServerTLS: ", err)
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}
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}
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