[tor-commits] [snowflake/master] Use ListenAndServe{TLS} rather than separate Listen and Serve.
dcf at torproject.org
dcf at torproject.org
Wed Mar 14 02:21:20 UTC 2018
commit 19b317e7814cc0cfaab8b20bc61c3663005c02dc
Author: David Fifield <david at bamsoftware.com>
Date: Mon Mar 12 13:34:57 2018 -0700
Use ListenAndServe{TLS} rather than separate Listen and Serve.
This is a port of commit cea86c937dc278ba6b2100c238b1d5206bbae2f0 from
meek. Its purpose is to remove the need to copy-paste parts of
net/http.Server.ListenAndServeTLS. Here is a copy of the commit message
from meek:
The net/http package provides ListenAndServe and ListenAndServeTLS
functions, but it doesn't provide a way to set up a listener without
also entering an infinite serve loop. This matters for
ListenAndServeTLS, which sets up a lot of magic behind the scenes for
TLS and HTTP/2 support. Formerly, we had copy-pasted code from
ListenAndServeTLS, but that code has only gotten more complicated in
upstream net/http.
The price we pay for this is that it's no longer possible for a server
bindaddr to ask to listen on port 0 (i.e., a random ephemeral port).
That's because we never get a change to find out what the listening
address is, before entering the serve loop.
What we gain is HTTP/2 support; formerly our copy-pasted code had the
side effect of disabling HTTP/2, because it was copied from an older
version and did things like
config.NextProtos = []string{"http/1.1"}
The new code calls http2.ConfigureServer first, but that's not what's
providing HTTP/2 support. HTTP/2 support happens by default. The reason
we call http2.ConfigureServer is because we need to set
TLSConfig.GetCertificate, and http2.ConfigureServer is a convenient way
to initialize TLSConfig in a way that is guaranteed to work with HTTP/2.
---
server/server.go | 116 ++++++++++++++++++++++++++++---------------------------
1 file changed, 60 insertions(+), 56 deletions(-)
diff --git a/server/server.go b/server/server.go
index 5ec3ff9..8fd703a 100644
--- a/server/server.go
+++ b/server/server.go
@@ -22,6 +22,7 @@ import (
"git.torproject.org/pluggable-transports/goptlib.git"
"git.torproject.org/pluggable-transports/websocket.git/websocket"
"golang.org/x/crypto/acme/autocert"
+ "golang.org/x/net/http2"
)
const ptMethodName = "snowflake"
@@ -171,64 +172,63 @@ func webSocketHandler(ws *websocket.WebSocket) {
proxy(or, &conn)
}
-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
- // infinite loop).
+func initServer(addr *net.TCPAddr,
+ getCertificate func(*tls.ClientHelloInfo) (*tls.Certificate, error),
+ listenAndServe func(*http.Server)) (*http.Server, error) {
+ // We're not capable of listening on port 0 (i.e., an ephemeral port
+ // unknown in advance). The reason is that while the net/http package
+ // exposes ListenAndServe and ListenAndServeTLS, those functions never
+ // return, so there's no opportunity to find out what the port number
+ // is, in between the Listen and Serve steps.
// https://groups.google.com/d/msg/Golang-nuts/3F1VRCCENp8/3hcayZiwYM8J
- config := &tls.Config{}
- config.NextProtos = []string{"http/1.1"}
- config.GetCertificate = m.GetCertificate
+ if addr.Port == 0 {
+ return nil, fmt.Errorf("cannot listen on port %d; configure a port using ServerTransportListenAddr", addr.Port)
+ }
- conn, err := net.ListenTCP(network, addr)
+ var config websocket.Config
+ config.MaxMessageSize = maxMessageSize
+ server := &http.Server{
+ Addr: addr.String(),
+ Handler: config.Handler(webSocketHandler),
+ ReadTimeout: requestTimeout,
+ }
+ // We need to override server.TLSConfig.GetCertificate--but first
+ // server.TLSConfig needs to be non-nil. If we just create our own new
+ // &tls.Config, it will lack the default settings that the net/http
+ // package sets up for things like HTTP/2. Therefore we first call
+ // http2.ConfigureServer for its side effect of initializing
+ // server.TLSConfig properly. An alternative would be to make a dummy
+ // net.Listener, call Serve on it, and let it return.
+ // https://github.com/golang/go/issues/16588#issuecomment-237386446
+ err := http2.ConfigureServer(server, nil)
if err != nil {
- return nil, err
+ return server, err
}
+ server.TLSConfig.GetCertificate = getCertificate
- // Additionally disable SSLv3 because of the POODLE attack.
- // http://googleonlinesecurity.blogspot.com/2014/10/this-poodle-bites-exploiting-ssl-30.html
- // https://code.google.com/p/go/source/detail?r=ad9e191a51946e43f1abac8b6a2fefbf2291eea7
- config.MinVersion = tls.VersionTLS10
-
- tlsListener := tls.NewListener(conn, config)
-
- return tlsListener, nil
-}
+ go listenAndServe(server)
-func startListener(network string, addr *net.TCPAddr) (net.Listener, error) {
- ln, err := net.ListenTCP(network, addr)
- if err != nil {
- return nil, err
- }
- log.Printf("listening with plain HTTP on %s", ln.Addr())
- return startServer(ln)
+ return server, nil
}
-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
- }
- log.Printf("listening with HTTPS on %s", ln.Addr())
- return startServer(ln)
+func startServer(addr *net.TCPAddr) (*http.Server, error) {
+ return initServer(addr, nil, func(server *http.Server) {
+ log.Printf("listening with plain HTTP on %s", addr)
+ err := server.ListenAndServe()
+ if err != nil {
+ log.Printf("error in ListenAndServe: %s", err)
+ }
+ })
}
-func startServer(ln net.Listener) (net.Listener, error) {
- go func() {
- defer ln.Close()
- var config websocket.Config
- config.MaxMessageSize = maxMessageSize
- s := &http.Server{
- Handler: config.Handler(webSocketHandler),
- ReadTimeout: requestTimeout,
- }
- err := s.Serve(ln)
+func startServerTLS(addr *net.TCPAddr, getCertificate func(*tls.ClientHelloInfo) (*tls.Certificate, error)) (*http.Server, error) {
+ return initServer(addr, getCertificate, func(server *http.Server) {
+ log.Printf("listening with HTTPS on %s", addr)
+ err := server.ListenAndServeTLS("", "")
if err != nil {
- log.Printf("http.Serve: %s", err)
+ log.Printf("error in ListenAndServeTLS: %s", err)
}
- }()
- return ln, nil
+ })
}
func getCertificateCacheDir() (string, error) {
@@ -303,7 +303,7 @@ func main() {
// https://github.com/ietf-wg-acme/acme/blob/master/draft-ietf-acme-acme.md#http-challenge
needHTTP01Listener := !disableTLS
- listeners := make([]net.Listener, 0)
+ servers := make([]*http.Server, 0)
for _, bindaddr := range ptInfo.Bindaddrs {
if bindaddr.MethodName != ptMethodName {
pt.SmethodError(bindaddr.MethodName, "no such method")
@@ -320,32 +320,36 @@ func main() {
pt.SmethodError(bindaddr.MethodName, "HTTP-01 ACME listener: "+err.Error())
continue
}
+ server := &http.Server{
+ Addr: addr.String(),
+ Handler: certManager.HTTPHandler(nil),
+ }
go func() {
- log.Fatal(http.Serve(lnHTTP01, certManager.HTTPHandler(nil)))
+ log.Fatal(server.Serve(lnHTTP01))
}()
- listeners = append(listeners, lnHTTP01)
+ servers = append(servers, server)
needHTTP01Listener = false
}
- var ln net.Listener
+ var server *http.Server
args := pt.Args{}
if disableTLS {
args.Add("tls", "no")
- ln, err = startListener("tcp", bindaddr.Addr)
+ server, err = startServer(bindaddr.Addr)
} else {
args.Add("tls", "yes")
for _, hostname := range acmeHostnames {
args.Add("hostname", hostname)
}
- ln, err = startListenerTLS("tcp", bindaddr.Addr, certManager)
+ server, err = startServerTLS(bindaddr.Addr, certManager.GetCertificate)
}
if err != nil {
log.Printf("error opening listener: %s", err)
pt.SmethodError(bindaddr.MethodName, err.Error())
continue
}
- pt.SmethodArgs(bindaddr.MethodName, ln.Addr(), args)
- listeners = append(listeners, ln)
+ pt.SmethodArgs(bindaddr.MethodName, bindaddr.Addr, args)
+ servers = append(servers, server)
}
pt.SmethodsDone()
@@ -366,8 +370,8 @@ func main() {
// signal received, shut down
log.Printf("caught signal %q, exiting", sig)
- for _, ln := range listeners {
- ln.Close()
+ for _, server := range servers {
+ server.Close()
}
for n := range handlerChan {
numHandlers += n
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