From 151c3fea88f454c3cde290e9e4ea6f3ea6da59e3 Mon Sep 17 00:00:00 2001
From: AJ ONeal <awesome@coolaj86.com>
Date: Tue, 14 Jul 2015 00:14:48 -0600
Subject: [PATCH] dynamic SNI loading

---
 serve.go | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 83 insertions(+), 5 deletions(-)

diff --git a/serve.go b/serve.go
index 58afce1..9d0fc1b 100644
--- a/serve.go
+++ b/serve.go
@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 )
 
 func usage() {
@@ -20,7 +21,14 @@ func usage() {
 	os.Exit(2)
 }
 
-type myHandler struct{}
+type myHandler struct {
+	certMap map[string]tls.Certificate
+}
+
+type myCert struct {
+	cert      *tls.Certificate
+	touchedAt time.Time
+}
 
 func (m *myHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Print debug info
@@ -31,9 +39,13 @@ func (m *myHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	for k, v := range r.Header {
 		fmt.Println(k, v)
 	}
+
 	fmt.Println(r.Body)
+	fmt.Println()
+	fmt.Println()
 
 	// End the request
+	// TODO serve from hosting directory
 	fmt.Fprintf(w, "Hi there, %s %q? Wow!\n\nWith Love,\n\t%s", r.Method, r.URL.Path[1:], r.Host)
 }
 
@@ -58,7 +70,7 @@ func main() {
 	fmt.Printf("Loading Certificates %s/%s/{privkey.pem,fullchain.pem}\n", *certsPath, *defaultHost)
 	privkeyPath := filepath.Join(*certsPath, *defaultHost, "privkey.pem")
 	certPath := filepath.Join(*certsPath, *defaultHost, "fullchain.pem")
-	cert, err := tls.LoadX509KeyPair(certPath, privkeyPath)
+	defaultCert, err := tls.LoadX509KeyPair(certPath, privkeyPath)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Couldn't load default certificates: %s\n", err)
 		os.Exit(1)
@@ -72,10 +84,76 @@ func main() {
 		os.Exit(1)
 	}
 
+	certMap := make(map[string]myCert)
 	tlsConfig := new(tls.Config)
-	tlsConfig.Certificates = []tls.Certificate{cert}
+	tlsConfig.Certificates = []tls.Certificate{defaultCert}
 	tlsConfig.GetCertificate = func(clientHello *tls.ClientHelloInfo) (*tls.Certificate, error) {
-		return &cert, nil
+
+		// Load from memory
+		// TODO unload untouched certificates every x minutes
+		if myCert, ok := certMap[clientHello.ServerName]; ok {
+			myCert.touchedAt = time.Now()
+			return myCert.cert, nil
+		}
+
+		privkeyPath := filepath.Join(*certsPath, clientHello.ServerName, "privkey.pem")
+		certPath := filepath.Join(*certsPath, clientHello.ServerName, "fullchain.pem")
+
+		loadCert := func() *tls.Certificate {
+			// TODO handle race condition (ask Matt)
+			// the transaction is idempotent, however, so it shouldn't matter
+			if _, err := os.Stat(privkeyPath); err == nil {
+				fmt.Printf("Loading Certificates %s/%s/{privkey.pem,fullchain.pem}\n\n", *certsPath, clientHello.ServerName)
+				cert, err := tls.LoadX509KeyPair(certPath, privkeyPath)
+				if nil != err {
+					return &cert
+				}
+				return nil
+			}
+
+			return nil
+		}
+
+		if cert := loadCert(); nil != cert {
+			certMap[clientHello.ServerName] = myCert{
+				cert:      cert,
+				touchedAt: time.Now(),
+			}
+			return cert, nil
+		}
+
+		// TODO try to get cert via letsencrypt python client
+		// TODO check for a hosting directory before attempting this
+		/*
+			cmd := exec.Command(
+				"./venv/bin/letsencrypt",
+				"--text",
+				"--agree-eula",
+				"--email", "coolaj86@gmail.com",
+				"--authenticator", "standalone",
+				"--domains", "www.example.com", "example.com",
+				"--dvsni-port", "65443",
+				"auth",
+			)
+			err := cmd.Run()
+			if nil != err {
+				if cert := loadCert(); nil != cert {
+					return cert, nil
+				}
+			}
+		*/
+
+		fmt.Fprintf(os.Stderr, "Failed to load certificates for %q.\n", clientHello.ServerName)
+		fmt.Fprintf(os.Stderr, "\tTried %s/{privkey.pem,fullchain.pem}\n", filepath.Join(*certsPath, clientHello.ServerName))
+		//fmt.Fprintf(os.Stderr, "\tand letsencrypt api\n")
+		fmt.Fprintf(os.Stderr, "\n")
+		// TODO how to prevent attack and still enable retry?
+		// perhaps check DNS and hosting directory, wait 5 minutes?
+		certMap[clientHello.ServerName] = myCert{
+			cert:      &defaultCert,
+			touchedAt: time.Now(),
+		}
+		return &defaultCert, nil
 	}
 	tlsListener := tls.NewListener(conn, tlsConfig)
 
@@ -83,6 +161,6 @@ func main() {
 		Addr:    addr,
 		Handler: &myHandler{},
 	}
-	fmt.Printf("Listening on https://%s:%d\n", host, *port)
+	fmt.Printf("Listening on https://%s:%d\n\n", host, *port)
 	server.Serve(tlsListener)
 }