Merge pull request #142 from writeas/autocert

Automatic certificates from Let's Encrypt

Resolves T542

app.go

@@ -11,6 +11,7 @@
 package writefreely
 
 import (
+	"crypto/tls"
 	"database/sql"
 	"fmt"
 	"html/template"
@@ -39,6 +40,7 @@ import (
 	"github.com/writeas/writefreely/key"
 	"github.com/writeas/writefreely/migrations"
 	"github.com/writeas/writefreely/page"
+	"golang.org/x/crypto/acme/autocert"
 )
 
 const (
@@ -380,19 +382,55 @@ func Serve(app *App, r *mux.Router) {
 	}
 	var err error
 	if app.cfg.IsSecureStandalone() {
+		if app.cfg.Server.Autocert {
+			m := &autocert.Manager{
+				Prompt: autocert.AcceptTOS,
+				Cache:  autocert.DirCache(app.cfg.Server.TLSCertPath),
+			}
+			host, err := url.Parse(app.cfg.App.Host)
+			if err != nil {
+				log.Error("[WARNING] Unable to parse configured host! %s", err)
+				log.Error(`[WARNING] ALL hosts are allowed, which can open you to an attack where
+clients connect to a server by IP address and pretend to be asking for an
+incorrect host name, and cause you to reach the CA's rate limit for certificate
+requests. We recommend supplying a valid host name.`)
+				log.Info("Using autocert on ANY host")
+			} else {
+				log.Info("Using autocert on host %s", host.Host)
+				m.HostPolicy = autocert.HostWhitelist(host.Host)
+			}
+			s := &http.Server{
+				Addr:    ":https",
+				Handler: r,
+				TLSConfig: &tls.Config{
+					GetCertificate: m.GetCertificate,
+				},
+			}
+			s.SetKeepAlivesEnabled(false)
+
+			go func() {
 				log.Info("Serving redirects on http://%s:80", bindAddress)
+				err = http.ListenAndServe(":80", m.HTTPHandler(nil))
+				log.Error("Unable to start redirect server: %v", err)
+			}()
+
+			log.Info("Serving on https://%s:443", bindAddress)
+			log.Info("---")
+			err = s.ListenAndServeTLS("", "")
+		} else {
 			go func() {
-			err = http.ListenAndServe(
+				log.Info("Serving redirects on http://%s:80", bindAddress)
-				fmt.Sprintf("%s:80", bindAddress), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				err = http.ListenAndServe(fmt.Sprintf("%s:80", bindAddress), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 					http.Redirect(w, r, app.cfg.App.Host, http.StatusMovedPermanently)
 				}))
 				log.Error("Unable to start redirect server: %v", err)
 			}()
 
 			log.Info("Serving on https://%s:443", bindAddress)
+			log.Info("Using manual certificates")
 			log.Info("---")
-		err = http.ListenAndServeTLS(
+			err = http.ListenAndServeTLS(fmt.Sprintf("%s:443", bindAddress), app.cfg.Server.TLSCertPath, app.cfg.Server.TLSKeyPath, r)
-			fmt.Sprintf("%s:443", bindAddress), app.cfg.Server.TLSCertPath, app.cfg.Server.TLSKeyPath, r)
+		}
 	} else {
 		log.Info("Serving on http://%s:%d\n", bindAddress, app.cfg.Server.Port)
 		log.Info("---")

config/config.go

@@ -35,6 +35,7 @@ type (
 
 		TLSCertPath string `ini:"tls_cert_path"`
 		TLSKeyPath  string `ini:"tls_key_path"`
+		Autocert    bool   `ini:"autocert"`
 
 		TemplatesParentDir string `ini:"templates_parent_dir"`
 		StaticParentDir    string `ini:"static_parent_dir"`

config/setup.go

@@ -101,19 +101,23 @@ func Configure(fname string, configSections string) (*SetupData, error) {
 			selPrompt = promptui.Select{
 				Templates: selTmpls,
 				Label:     "Web server mode",
-				Items:     []string{"Insecure (port 80)", "Secure (port 443)"},
+				Items:     []string{"Insecure (port 80)", "Secure (port 443), manual certificate", "Secure (port 443), auto certificate"},
 			}
 			sel, _, err := selPrompt.Run()
 			if err != nil {
 				return data, err
 			}
 			if sel == 0 {
+				data.Config.Server.Autocert = false
 				data.Config.Server.Port = 80
 				data.Config.Server.TLSCertPath = ""
 				data.Config.Server.TLSKeyPath = ""
-			} else if sel == 1 {
+			} else if sel == 1 || sel == 2 {
 				data.Config.Server.Port = 443
+				data.Config.Server.Autocert = sel == 2
 
+				if sel == 1 {
+					// Manual certificate configuration
 					prompt = promptui.Prompt{
 						Templates: tmpls,
 						Label:     "Certificate path",
@@ -135,6 +139,11 @@ func Configure(fname string, configSections string) (*SetupData, error) {
 					if err != nil {
 						return data, err
 					}
+				} else {
+					// Automatic certificate
+					data.Config.Server.TLSCertPath = "certs"
+					data.Config.Server.TLSKeyPath = "certs"
+				}
 			}
 		} else {
 			data.Config.Server.TLSCertPath = ""