Add TLS support for CTLog server

Signed-off-by: Firas Ghanmi <fghanmi@redhat.com>

Author: fghanmi

trillian/ctfe/ct_server/main.go

@@ -21,6 +21,7 @@ import (
 	"crypto/ecdsa"
 	"crypto/ed25519"
 	"crypto/rsa"
+	"crypto/tls"
 	"flag"
 	"fmt"
 	"net/http"
@@ -57,6 +58,8 @@ import (
 // Global flags that affect all log instances.
 var (
 	httpEndpoint       = flag.String("http_endpoint", "localhost:6962", "Endpoint for HTTP (host:port)")
+	tlsCert            = flag.String("tls-certificate", "", "Path to server TLS certificate")
+	tlsKey             = flag.String("tls-key", "", "Path to server TLS private key")
 	metricsEndpoint    = flag.String("metrics_endpoint", "", "Endpoint for serving metrics; if left empty, metrics will be visible on --http_endpoint")
 	rpcBackend         = flag.String("log_rpc_server", "", "Backend specification; comma-separated list or etcd service name (if --etcd_servers specified). If unset backends are specified in config (as a LogMultiConfig proto)")
 	rpcDeadline        = flag.Duration("rpc_deadline", time.Second*10, "Deadline for backend RPC requests")
@@ -306,7 +309,19 @@ func main() {
 	}
 
 	// Bring up the HTTP server and serve until we get a signal not to.
-	srv := http.Server{Addr: *httpEndpoint, Handler: handler}
+	srv := http.Server{}
+	if *tlsCert == "" || *tlsKey == "" {
+		srv = http.Server{Addr: *httpEndpoint, Handler: handler}
+	} else {
+		cert, err := tls.LoadX509KeyPair(*tlsCert, *tlsKey)
+		if err != nil {
+			klog.Errorf("failed to load TLS certificate/key: %v", err)
+		}
+		tlsConfig := &tls.Config{
+			Certificates: []tls.Certificate{cert},
+		}
+		srv = http.Server{Addr: *httpEndpoint, Handler: handler, TLSConfig: tlsConfig}
+	}
 	shutdownWG := new(sync.WaitGroup)
 	go awaitSignal(func() {
 		shutdownWG.Add(1)