Use h2c from x/net to handle h2c requests

Co-authored-by: Mathieu Lonjaret <mathieu.lonjaret@gmail.com>

vendor/golang.org/x/net/proxy/dial.go

@@ -0,0 +1,54 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"context"
+	"net"
+)
+
+// A ContextDialer dials using a context.
+type ContextDialer interface {
+	DialContext(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+// Dial works like DialContext on net.Dialer but using a dialer returned by FromEnvironment.
+//
+// The passed ctx is only used for returning the Conn, not the lifetime of the Conn.
+//
+// Custom dialers (registered via RegisterDialerType) that do not implement ContextDialer
+// can leak a goroutine for as long as it takes the underlying Dialer implementation to timeout.
+//
+// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
+func Dial(ctx context.Context, network, address string) (net.Conn, error) {
+	d := FromEnvironment()
+	if xd, ok := d.(ContextDialer); ok {
+		return xd.DialContext(ctx, network, address)
+	}
+	return dialContext(ctx, d, network, address)
+}
+
+// WARNING: this can leak a goroutine for as long as the underlying Dialer implementation takes to timeout
+// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
+func dialContext(ctx context.Context, d Dialer, network, address string) (net.Conn, error) {
+	var (
+		conn net.Conn
+		done = make(chan struct{}, 1)
+		err  error
+	)
+	go func() {
+		conn, err = d.Dial(network, address)
+		close(done)
+		if conn != nil && ctx.Err() != nil {
+			conn.Close()
+		}
+	}()
+	select {
+	case <-ctx.Done():
+		err = ctx.Err()
+	case <-done:
+	}
+	return conn, err
+}

vendor/golang.org/x/net/proxy/direct.go

@@ -5,14 +5,27 @@
 package proxy
 
 import (
+	"context"
 	"net"
 )
 
 type direct struct{}
 
-// Direct is a direct proxy: one that makes network connections directly.
+// Direct implements Dialer by making network connections directly using net.Dial or net.DialContext.
 var Direct = direct{}
 
+var (
+	_ Dialer        = Direct
+	_ ContextDialer = Direct
+)
+
+// Dial directly invokes net.Dial with the supplied parameters.
 func (direct) Dial(network, addr string) (net.Conn, error) {
 	return net.Dial(network, addr)
 }
+
+// DialContext instantiates a net.Dialer and invokes its DialContext receiver with the supplied parameters.
+func (direct) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	var d net.Dialer
+	return d.DialContext(ctx, network, addr)
+}

vendor/golang.org/x/net/proxy/per_host.go

@@ -5,6 +5,7 @@
 package proxy
 
 import (
+	"context"
 	"net"
 	"strings"
 )
@@ -41,6 +42,20 @@ func (p *PerHost) Dial(network, addr string) (c net.Conn, err error) {
 	return p.dialerForRequest(host).Dial(network, addr)
 }
 
+// DialContext connects to the address addr on the given network through either
+// defaultDialer or bypass.
+func (p *PerHost) DialContext(ctx context.Context, network, addr string) (c net.Conn, err error) {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+	d := p.dialerForRequest(host)
+	if x, ok := d.(ContextDialer); ok {
+		return x.DialContext(ctx, network, addr)
+	}
+	return dialContext(ctx, d, network, addr)
+}
+
 func (p *PerHost) dialerForRequest(host string) Dialer {
 	if ip := net.ParseIP(host); ip != nil {
 		for _, net := range p.bypassNetworks {

vendor/golang.org/x/net/proxy/proxy.go

@@ -15,6 +15,7 @@ import (
 )
 
 // A Dialer is a means to establish a connection.
+// Custom dialers should also implement ContextDialer.
 type Dialer interface {
 	// Dial connects to the given address via the proxy.
 	Dial(network, addr string) (c net.Conn, err error)
@@ -25,21 +26,30 @@ type Auth struct {
 	User, Password string
 }
 
-// FromEnvironment returns the dialer specified by the proxy related variables in
-// the environment.
+// FromEnvironment returns the dialer specified by the proxy-related
+// variables in the environment and makes underlying connections
+// directly.
 func FromEnvironment() Dialer {
+	return FromEnvironmentUsing(Direct)
+}
+
+// FromEnvironmentUsing returns the dialer specify by the proxy-related
+// variables in the environment and makes underlying connections
+// using the provided forwarding Dialer (for instance, a *net.Dialer
+// with desired configuration).
+func FromEnvironmentUsing(forward Dialer) Dialer {
 	allProxy := allProxyEnv.Get()
 	if len(allProxy) == 0 {
-		return Direct
+		return forward
 	}
 
 	proxyURL, err := url.Parse(allProxy)
 	if err != nil {
-		return Direct
+		return forward
 	}
-	proxy, err := FromURL(proxyURL, Direct)
+	proxy, err := FromURL(proxyURL, forward)
 	if err != nil {
-		return Direct
+		return forward
 	}
 
 	noProxy := noProxyEnv.Get()
@@ -47,7 +57,7 @@ func FromEnvironment() Dialer {
 		return proxy
 	}
 
-	perHost := NewPerHost(proxy, Direct)
+	perHost := NewPerHost(proxy, forward)
 	perHost.AddFromString(noProxy)
 	return perHost
 }
@@ -79,8 +89,13 @@ func FromURL(u *url.URL, forward Dialer) (Dialer, error) {
 	}
 
 	switch u.Scheme {
-	case "socks5":
-		return SOCKS5("tcp", u.Host, auth, forward)
+	case "socks5", "socks5h":
+		addr := u.Hostname()
+		port := u.Port()
+		if port == "" {
+			port = "1080"
+		}
+		return SOCKS5("tcp", net.JoinHostPort(addr, port), auth, forward)
 	}
 
 	// If the scheme doesn't match any of the built-in schemes, see if it

vendor/golang.org/x/net/proxy/socks5.go

@@ -17,8 +17,14 @@ import (
 func SOCKS5(network, address string, auth *Auth, forward Dialer) (Dialer, error) {
 	d := socks.NewDialer(network, address)
 	if forward != nil {
-		d.ProxyDial = func(_ context.Context, network string, address string) (net.Conn, error) {
-			return forward.Dial(network, address)
+		if f, ok := forward.(ContextDialer); ok {
+			d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
+				return f.DialContext(ctx, network, address)
+			}
+		} else {
+			d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
+				return dialContext(ctx, forward, network, address)
+			}
 		}
 	}
 	if auth != nil {