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Use ListenAndServe{TLS} rather than separate Listen and Serve.

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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.
This commit is contained in:
David Fifield 2018-03-12 13:34:57 -07:00
parent c61336c897
commit 19b317e781
1 changed files with 62 additions and 58 deletions
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120
server/server.go
View file

@ -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
conn, err := net.ListenTCP(network, addr)
if err != nil {
return nil, err
if addr.Port == 0 {
return nil, fmt.Errorf("cannot listen on port %d; configure a port using ServerTransportListenAddr", addr.Port)
}
// 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
}
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)
}
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(ln net.Listener) (net.Listener, error) {
go func() {
defer ln.Close()
var config websocket.Config
config.MaxMessageSize = maxMessageSize
s := &http.Server{
server := &http.Server{
Addr: addr.String(),
Handler: config.Handler(webSocketHandler),
ReadTimeout: requestTimeout,
}
err := s.Serve(ln)
// 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 {
log.Printf("http.Serve: %s", err)
return server, err
}
}()
return ln, nil
server.TLSConfig.GetCertificate = getCertificate
go listenAndServe(server)
return server, nil
}
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 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("error in ListenAndServeTLS: %s", err)
}
})
}
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