automatically reload TLS certificates when they change (#3598)

* Dynamically refresh tls certs for all servers

* make sure that CertLoader is always closed

---------

Co-authored-by: aler9 <46489434+aler9@users.noreply.github.com>

internal/certloader/certloader.go

@@ -0,0 +1,108 @@
+// Package certloader contains a certicate loader.
+package certloader
+
+import (
+	"crypto/tls"
+	"sync"
+
+	"github.com/bluenviron/mediamtx/internal/confwatcher"
+	"github.com/bluenviron/mediamtx/internal/logger"
+)
+
+// CertLoader is a certificate loader. It watches for changes to the certificate and key files.
+type CertLoader struct {
+	log                     logger.Writer
+	certWatcher, keyWatcher *confwatcher.ConfWatcher
+	certPath, keyPath       string
+	done                    chan struct{}
+
+	cert   *tls.Certificate
+	certMu sync.RWMutex
+}
+
+// New allocates a CertLoader.
+func New(certPath, keyPath string, log logger.Writer) (*CertLoader, error) {
+	cl := &CertLoader{
+		log:      log,
+		certPath: certPath,
+		keyPath:  keyPath,
+		done:     make(chan struct{}),
+	}
+
+	var err error
+	cl.certWatcher, err = confwatcher.New(certPath)
+	if err != nil {
+		return nil, err
+	}
+
+	cl.keyWatcher, err = confwatcher.New(keyPath)
+	if err != nil {
+		cl.certWatcher.Close() //nolint:errcheck
+		return nil, err
+	}
+
+	cert, err := tls.LoadX509KeyPair(certPath, keyPath)
+	if err != nil {
+		return nil, err
+	}
+
+	cl.certMu.Lock()
+	cl.cert = &cert
+	cl.certMu.Unlock()
+
+	go cl.watch()
+
+	return cl, nil
+}
+
+// Close closes a CertLoader and releases any underlying resources.
+func (cl *CertLoader) Close() {
+	close(cl.done)
+	cl.certWatcher.Close() //nolint:errcheck
+	cl.keyWatcher.Close()  //nolint:errcheck
+	cl.certMu.Lock()
+	defer cl.certMu.Unlock()
+	cl.cert = nil
+}
+
+// GetCertificate returns a function that returns the certificate for use in a tls.Config.
+func (cl *CertLoader) GetCertificate() func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
+	return func(_ *tls.ClientHelloInfo) (*tls.Certificate, error) {
+		cl.certMu.RLock()
+		defer cl.certMu.RUnlock()
+		return cl.cert, nil
+	}
+}
+
+func (cl *CertLoader) watch() {
+	for {
+		select {
+		case <-cl.certWatcher.Watch():
+			cert, err := tls.LoadX509KeyPair(cl.certPath, cl.keyPath)
+			if err != nil {
+				cl.log.Log(logger.Error, "certloader failed to load after change to %s: %s", cl.certPath, err.Error())
+				continue
+			}
+
+			cl.certMu.Lock()
+			cl.cert = &cert
+			cl.certMu.Unlock()
+
+			cl.log.Log(logger.Info, "certificate reloaded after change to %s", cl.certPath)
+		case <-cl.keyWatcher.Watch():
+			cert, err := tls.LoadX509KeyPair(cl.certPath, cl.keyPath)
+			if err != nil {
+				cl.log.Log(logger.Error, "certloader failed to load after change to %s: %s", cl.keyPath, err.Error())
+				continue
+			}
+
+			cl.certMu.Lock()
+			cl.cert = &cert
+			cl.certMu.Unlock()
+
+			cl.log.Log(logger.Info, "certificate reloaded after change to %s", cl.keyPath)
+		case <-cl.done:
+			return
+		}
+	}
+}

internal/certloader/certloader_test.go

@@ -0,0 +1,52 @@
+package certloader
+
+import (
+	"crypto/tls"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/bluenviron/mediamtx/internal/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCertReload(t *testing.T) {
+	testData, err := tls.X509KeyPair(test.TLSCertPub, test.TLSCertKey)
+	require.NoError(t, err)
+
+	serverCertPath, err := test.CreateTempFile(test.TLSCertPub)
+	require.NoError(t, err)
+	defer os.Remove(serverCertPath)
+
+	serverKeyPath, err := test.CreateTempFile(test.TLSCertKey)
+	require.NoError(t, err)
+	defer os.Remove(serverKeyPath)
+
+	loader, err := New(serverCertPath, serverKeyPath, test.NilLogger)
+	require.NoError(t, err)
+	defer loader.Close()
+
+	getCert := loader.GetCertificate()
+	require.NotNil(t, getCert)
+
+	cert, err := getCert(nil)
+	require.NoError(t, err)
+	require.NotNil(t, cert)
+	require.Equal(t, &testData, cert)
+
+	testData, err = tls.X509KeyPair(test.TLSCertPubAlt, test.TLSCertKeyAlt)
+	require.NoError(t, err)
+
+	err = os.WriteFile(serverCertPath, test.TLSCertPubAlt, 0o644)
+	require.NoError(t, err)
+
+	err = os.WriteFile(serverKeyPath, test.TLSCertKeyAlt, 0o644)
+	require.NoError(t, err)
+
+	time.Sleep(1 * time.Second)
+
+	cert, err = getCert(nil)
+	require.NoError(t, err)
+	require.NotNil(t, cert)
+	require.Equal(t, &testData, cert)
+}

internal/protocols/httpp/wrapped_server.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/bluenviron/mediamtx/internal/certloader"
 	"github.com/bluenviron/mediamtx/internal/logger"
 )
 
@@ -36,8 +37,9 @@ type WrappedServer struct {
 	Handler     http.Handler
 	Parent      logger.Writer
 
-	ln    net.Listener
-	inner *http.Server
+	ln     net.Listener
+	inner  *http.Server
+	loader *certloader.CertLoader
 }
 
 // Initialize initializes a WrappedServer.
@@ -47,13 +49,15 @@ func (s *WrappedServer) Initialize() error {
 		if s.ServerCert == "" {
 			return fmt.Errorf("server cert is missing")
 		}
-		crt, err := tls.LoadX509KeyPair(s.ServerCert, s.ServerKey)
+
+		var err error
+		s.loader, err = certloader.New(s.ServerCert, s.ServerKey, s.Parent)
 		if err != nil {
 			return err
 		}
 
 		tlsConfig = &tls.Config{
-			Certificates: []tls.Certificate{crt},
+			GetCertificate: s.loader.GetCertificate(),
 		}
 	}
 
@@ -92,4 +96,7 @@ func (s *WrappedServer) Close() {
 	ctxCancel()
 	s.inner.Shutdown(ctx)
 	s.ln.Close() // in case Shutdown() is called before Serve()
+	if s.loader != nil {
+		s.loader.Close()
+	}
 }

internal/servers/rtmp/server.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/bluenviron/mediamtx/internal/certloader"
 	"github.com/bluenviron/mediamtx/internal/conf"
 	"github.com/bluenviron/mediamtx/internal/defs"
 	"github.com/bluenviron/mediamtx/internal/externalcmd"
@@ -82,6 +83,7 @@ type Server struct {
 	wg        sync.WaitGroup
 	ln        net.Listener
 	conns     map[*conn]struct{}
+	loader    *certloader.CertLoader
 
 	// in
 	chNewConn      chan net.Conn
@@ -99,13 +101,14 @@ func (s *Server) Initialize() error {
 			return net.Listen(restrictnetwork.Restrict("tcp", s.Address))
 		}
 
-		cert, err := tls.LoadX509KeyPair(s.ServerCert, s.ServerKey)
+		var err error
+		s.loader, err = certloader.New(s.ServerCert, s.ServerKey, s.Parent)
 		if err != nil {
 			return nil, err
 		}
 
 		network, address := restrictnetwork.Restrict("tcp", s.Address)
-		return tls.Listen(network, address, &tls.Config{Certificates: []tls.Certificate{cert}})
+		return tls.Listen(network, address, &tls.Config{GetCertificate: s.loader.GetCertificate()})
 	}()
 	if err != nil {
 		return err
@@ -153,6 +156,9 @@ func (s *Server) Close() {
 	s.Log(logger.Info, "listener is closing")
 	s.ctxCancel()
 	s.wg.Wait()
+	if s.loader != nil {
+		s.loader.Close()
+	}
 }
 
 func (s *Server) run() {

internal/servers/rtsp/server.go

@@ -17,6 +17,7 @@ import (
 	"github.com/bluenviron/gortsplib/v4/pkg/liberrors"
 	"github.com/google/uuid"
 
+	"github.com/bluenviron/mediamtx/internal/certloader"
 	"github.com/bluenviron/mediamtx/internal/conf"
 	"github.com/bluenviron/mediamtx/internal/defs"
 	"github.com/bluenviron/mediamtx/internal/externalcmd"
@@ -89,6 +90,7 @@ type Server struct {
 	mutex     sync.RWMutex
 	conns     map[*gortsplib.ServerConn]*conn
 	sessions  map[*gortsplib.ServerSession]*session
+	loader    *certloader.CertLoader
 }
 
 // Initialize initializes the server.
@@ -118,12 +120,13 @@ func (s *Server) Initialize() error {
 	}
 
 	if s.IsTLS {
-		cert, err := tls.LoadX509KeyPair(s.ServerCert, s.ServerKey)
+		var err error
+		s.loader, err = certloader.New(s.ServerCert, s.ServerKey, s.Parent)
 		if err != nil {
 			return err
 		}
 
-		s.srv.TLSConfig = &tls.Config{Certificates: []tls.Certificate{cert}}
+		s.srv.TLSConfig = &tls.Config{GetCertificate: s.loader.GetCertificate()}
 	}
 
 	err := s.srv.Start()
@@ -155,6 +158,9 @@ func (s *Server) Close() {
 	s.Log(logger.Info, "listener is closing")
 	s.ctxCancel()
 	s.wg.Wait()
+	if s.loader != nil {
+		s.loader.Close()
+	}
 }
 
 func (s *Server) run() {

internal/test/tls_cert.go

@@ -53,3 +53,55 @@ y++U32uuSFiXDcSLarfIsE992MEJLSAynbF1Rsgsr3gXbGiuToJRyxbIeVy7gwzD
 +3K6cnKEyg+0ekYmLertRFIY6SwWmY1fyKgTvxudMcsBY7dC4xs=
 -----END RSA PRIVATE KEY-----
 `)
+
+// TLSCertPubAlt is the public key of an alternative test certificate.
+var TLSCertPubAlt = []byte(`-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`)
+
+// TLSCertKeyAlt is the private key of an alternative test certificate.
+var TLSCertKeyAlt = []byte(`-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----
+`)