[tor-commits] [snowflake/master] Automatically fetch certificates from Let's Encrypt.
dcf at torproject.org
dcf at torproject.org
Fri Mar 31 02:16:53 UTC 2017
commit 61310600c3dc419da5661dba9b11da57acd5188f
Author: David Fifield <david at bamsoftware.com>
Date: Wed Jan 18 19:19:26 2017 -0800
Automatically fetch certificates from Let's Encrypt.
This removes the --tls-cert and --tls-keys options and replaces them
with --acme-hostname and (optional) --acme-email. It uses
https://godoc.org/golang.org/x/crypto/acme/autocert, which is kind of a
successor to https://godoc.org/rsc.io/letsencrypt.
The autocert package only works when the listener runs on port 443. For
that reason, if TOR_PT_SERVER_BINDADDR asks for a port other than 443,
the program will open an *additional* listening port on 443. If there is
an error opening the listener, it is reported through an SMETHOD-ERROR
for the requested address.
The inspiration for this code came from George Tankersley's patch for
meek-server:
https://bugs.torproject.org/18655#comment:8
https://github.com/gtank/meek/tree/letsencrypt
---
server/server.go | 70 ++++++++++++++++++++++++++++++++++++++------------------
server/torrc | 4 ++--
2 files changed, 50 insertions(+), 24 deletions(-)
diff --git a/server/server.go b/server/server.go
index 8025ad3..bedc70c 100644
--- a/server/server.go
+++ b/server/server.go
@@ -19,12 +19,14 @@ import (
"net/http"
"os"
"os/signal"
+ "strings"
"sync"
"syscall"
"time"
"git.torproject.org/pluggable-transports/goptlib.git"
"git.torproject.org/pluggable-transports/websocket.git/websocket"
+ "golang.org/x/crypto/acme/autocert"
)
const ptMethodName = "snowflake"
@@ -150,7 +152,7 @@ func webSocketHandler(ws *websocket.WebSocket) {
proxy(or, &conn)
}
-func listenTLS(network string, addr *net.TCPAddr, certFilename, keyFilename string) (net.Listener, error) {
+func listenTLS(network string, addr *net.TCPAddr, m *autocert.Manager) (net.Listener, error) {
// This is cribbed from the source of net/http.Server.ListenAndServeTLS.
// We have to separate the Listen and Serve parts because we need to
// report the listening address before entering Serve (which is an
@@ -158,13 +160,7 @@ func listenTLS(network string, addr *net.TCPAddr, certFilename, keyFilename stri
// https://groups.google.com/d/msg/Golang-nuts/3F1VRCCENp8/3hcayZiwYM8J
config := &tls.Config{}
config.NextProtos = []string{"http/1.1"}
-
- var err error
- config.Certificates = make([]tls.Certificate, 1)
- config.Certificates[0], err = tls.LoadX509KeyPair(certFilename, keyFilename)
- if err != nil {
- return nil, err
- }
+ config.GetCertificate = m.GetCertificate
conn, err := net.ListenTCP(network, addr)
if err != nil {
@@ -190,8 +186,8 @@ func startListener(network string, addr *net.TCPAddr) (net.Listener, error) {
return startServer(ln)
}
-func startListenerTLS(network string, addr *net.TCPAddr, certFilename, keyFilename string) (net.Listener, error) {
- ln, err := listenTLS(network, addr, certFilename, keyFilename)
+func startListenerTLS(network string, addr *net.TCPAddr, m *autocert.Manager) (net.Listener, error) {
+ ln, err := listenTLS(network, addr, m)
if err != nil {
return nil, err
}
@@ -217,14 +213,13 @@ func startServer(ln net.Listener) (net.Listener, error) {
}
func main() {
+ var acmeHostnamesCommas string
var disableTLS bool
- var certFilename, keyFilename string
var logFilename string
flag.Usage = usage
+ flag.StringVar(&acmeHostnamesCommas, "acme-hostnames", "", "comma-separated hostnames for TLS certificate")
flag.BoolVar(&disableTLS, "disable-tls", false, "don't use HTTPS")
- flag.StringVar(&certFilename, "cert", "", "TLS certificate file (required without --disable-tls)")
- flag.StringVar(&keyFilename, "key", "", "TLS private key file (required without --disable-tls)")
flag.StringVar(&logFilename, "log", "", "log file to write to")
flag.Parse()
@@ -237,15 +232,10 @@ func main() {
log.SetOutput(f)
}
- if disableTLS {
- if certFilename != "" || keyFilename != "" {
- log.Fatalf("the --cert and --key options are not allowed with --disable-tls")
- }
- } else {
- if certFilename == "" || keyFilename == "" {
- log.Fatalf("the --cert and --key options are required")
- }
+ if !disableTLS && acmeHostnamesCommas == "" {
+ log.Fatal("the --acme-hostnames option is required")
}
+ acmeHostnames := strings.Split(acmeHostnamesCommas, ",")
log.Printf("starting")
var err error
@@ -254,6 +244,28 @@ func main() {
log.Fatalf("error in setup: %s", err)
}
+ if !disableTLS {
+ log.Printf("ACME hostnames: %q", acmeHostnames)
+ }
+ certManager := autocert.Manager{
+ Prompt: autocert.AcceptTOS,
+ HostPolicy: autocert.HostWhitelist(acmeHostnames...),
+ }
+
+ // The ACME responder only works when it is running on port 443. In case
+ // there is not already going to be a TLS listener on port 443, we need
+ // to open an additional one. The port is actually opened in the loop
+ // below, so that any errors can be reported in the SMETHOD-ERROR of
+ // another bindaddr.
+ // https://letsencrypt.github.io/acme-spec/#domain-validation-with-server-name-indication-dvsni
+ need443Listener := !disableTLS
+ for _, bindaddr := range ptInfo.Bindaddrs {
+ if !disableTLS && bindaddr.Addr.Port == 443 {
+ need443Listener = false
+ break
+ }
+ }
+
listeners := make([]net.Listener, 0)
for _, bindaddr := range ptInfo.Bindaddrs {
if bindaddr.MethodName != ptMethodName {
@@ -261,6 +273,20 @@ func main() {
continue
}
+ if need443Listener {
+ addr := *bindaddr.Addr
+ addr.Port = 443
+ log.Printf("opening additional ACME listener on %s", addr.String())
+ ln443, err := startListenerTLS("tcp", &addr, &certManager)
+ if err != nil {
+ log.Printf("error opening ACME listener: %s", err)
+ pt.SmethodError(bindaddr.MethodName, "ACME listener: "+err.Error())
+ continue
+ }
+ listeners = append(listeners, ln443)
+ need443Listener = false
+ }
+
var ln net.Listener
args := pt.Args{}
if disableTLS {
@@ -268,7 +294,7 @@ func main() {
ln, err = startListener("tcp", bindaddr.Addr)
} else {
args.Add("tls", "yes")
- ln, err = startListenerTLS("tcp", bindaddr.Addr, certFilename, keyFilename)
+ ln, err = startListenerTLS("tcp", bindaddr.Addr, &certManager)
}
if err != nil {
log.Printf("error opening listener: %s", err)
diff --git a/server/torrc b/server/torrc
index 74f6af0..ed71a39 100644
--- a/server/torrc
+++ b/server/torrc
@@ -5,5 +5,5 @@ SocksPort 0
ExitPolicy reject *:*
DataDirectory datadir
-ServerTransportListenAddr snowflake 0.0.0.0:9902
-ServerTransportPlugin snowflake exec ./server --disable-tls --log snowflake.log
+ServerTransportListenAddr snowflake 0.0.0.0:443
+ServerTransportPlugin snowflake exec ./server --acme-hostnames snowflake.example --acme-email admin at snowflake.example --log snowflake.log
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