feat: mTLS support (#68)

Signed-off-by: Jiri Novotny <k4chn1k@gmail.com>

README.md

@@ -30,6 +30,7 @@ This is the server program of [rtty](https://github.com/zhaojh329/rtty)
 	statik -src=frontend/dist
 
 ## Authorization
+### Token
 Generate a token
 
     $ rttys token
@@ -40,6 +41,11 @@ Use token
 
     $ rttys run -t 34762d07637276694b938d23f10d7164
 
+### mTLS
+You can enable mTLS by specifying device CA storage (valid file) in config file or from CLI (variable ssl-devs).
+Appending to CA storage is possible on-the-fly, you can reload CA certs by sendig SIGUSR1 signal.
+Device(s) without valid CA in storage will be disconnected in TLS handshake.
+
 ## Running as a Linux service
 Move the rttys binary into /usr/local/bin/
 

broker.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/binary"
+	"crypto/x509"
 
 	"github.com/gorilla/websocket"
 	jsoniter "github.com/json-iterator/go"
@@ -32,6 +33,7 @@ type broker struct {
 	userMessage    chan *usrMessage
 	cmdMessage     chan []byte
 	webMessage     chan *webResp
+	devCertPool    *x509.CertPool
 }
 
 func newBroker(cfg *config.Config) *broker {

build.sh

@@ -5,7 +5,7 @@ GitCommit=$(git log --pretty=format:"%h" -1)
 BuildTime=$(date +%FT%T%z)
 
 [ $# -lt 2 ] && {
-	echo "Usage: $0 linux amb64"
+	echo "Usage: $0 linux amd64"
 	exit 1
 }
 

config/config.go

@@ -19,6 +19,7 @@ type Config struct {
 	WebPort      int
 	SslCert      string
 	SslKey       string
+	SslDevices   string
 	HTTPUsername string
 	HTTPPassword string
 	Token        string
@@ -49,6 +50,7 @@ func Parse(c *cli.Context) *Config {
 		WebRedirURL:  c.String("web-redir-url"),
 		SslCert:      c.String("ssl-cert"),
 		SslKey:       c.String("ssl-key"),
+		SslDevices:   c.String("ssl-devs"),
 		HTTPUsername: c.String("http-username"),
 		HTTPPassword: c.String("http-password"),
 		Token:        c.String("token"),
@@ -74,6 +76,7 @@ func Parse(c *cli.Context) *Config {
 		getConfigOpt(yamlCfg, "web-redir-url", &cfg.WebRedirURL)
 		getConfigOpt(yamlCfg, "ssl-cert", &cfg.SslCert)
 		getConfigOpt(yamlCfg, "ssl-key", &cfg.SslKey)
+		getConfigOpt(yamlCfg, "ssl-devs", &cfg.SslDevices)
 		getConfigOpt(yamlCfg, "http-username", &cfg.HTTPUsername)
 		getConfigOpt(yamlCfg, "http-password", &cfg.HTTPPassword)
 		getConfigOpt(yamlCfg, "token", &cfg.Token)

device.go

@@ -6,8 +6,10 @@ import (
 	"context"
 	"crypto/rand"
 	"crypto/tls"
+	"crypto/x509"
 	"encoding/binary"
 	"io"
+	"io/ioutil"
 	"net"
 	"strings"
 	"sync"
@@ -272,6 +274,18 @@ func listenDevice(br *broker) {
 		tlsConfig.Time = time.Now
 		tlsConfig.Rand = rand.Reader
 
+		caCert, err := ioutil.ReadFile(cfg.SslDevices)
+		if err != nil {
+			log.Warn().Msgf("mTLS not used: %s", err.Error())
+		} else {
+			br.devCertPool = x509.NewCertPool()
+			br.devCertPool.AppendCertsFromPEM(caCert)
+
+			// Create the TLS Config with the CA pool and enable Client certificate validation
+			tlsConfig.ClientCAs = br.devCertPool
+			tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
+		}
+
 		ln = tls.NewListener(ln, tlsConfig)
 		log.Info().Msgf("Listen device on: %s SSL on", cfg.AddrDev)
 	} else {

main.go

@@ -3,7 +3,10 @@ package main
 import (
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 	"runtime"
+	"io/ioutil"
 
 	"github.com/rs/zerolog/log"
 	"github.com/urfave/cli/v2"
@@ -17,6 +20,8 @@ func runRttys(c *cli.Context) {
 	rlog.SetPath(c.String("log"))
 
 	cfg := config.Parse(c)
+	sigs := make(chan os.Signal, 1)
+	signal.Notify(sigs, syscall.SIGUSR1)
 
 	if cfg.HTTPUsername == "" {
 		fmt.Println("You must configure the http username by commandline or config file")
@@ -46,6 +51,26 @@ func runRttys(c *cli.Context) {
 	listenDeviceWeb(br)
 	httpStart(br)
 
+	go func() {
+		for {
+			s := <-sigs
+			switch s {
+			case syscall.SIGUSR1:
+				if br.devCertPool != nil {
+					log.Info().Msg("Reload certs for mTLS")
+					caCert, err := ioutil.ReadFile(cfg.SslDevices)
+					if err != nil {
+						log.Info().Msgf("mTLS update faled: %s", err.Error())
+					} else {
+						br.devCertPool.AppendCertsFromPEM(caCert)
+					}
+				} else {
+					log.Warn().Msg("Reload certs failed: mTLS not used")
+				}
+			}
+		}
+	}()
+
 	select {}
 }
 
@@ -105,6 +130,11 @@ func main() {
 						Value: "",
 						Usage: "ssl key file Path",
 					},
+					&cli.StringFlag{
+						Name:  "ssl-devs",
+						Value: "",
+						Usage: "mtls CA storage in PEM file Path",
+					},
 					&cli.StringFlag{
 						Name:  "http-username",
 						Value: "",