add http2 proxy example

http2_proxy.go

@@ -0,0 +1,208 @@
+// +build ignore
+
+package main
+
+/*
+this is a example of using http2 proxy
+this applet act http proxy and forward the request through http2 proxy
+
+usage example
+
+	go build -o proxy http2_proxy.go
+	./proxy -server www.example.com -listen :8088
+	curl --proxy http://localhost:8088/ https://httpbin.org/ip
+
+*/
+
+import (
+	"crypto/tls"
+	"flag"
+	"fmt"
+	"golang.org/x/net/http2"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"sync"
+)
+
+type clientConn struct {
+	host      string
+	port      string
+	hostname  string
+	transport *http2.Transport
+	conn      *http2.ClientConn
+	lock      *sync.Mutex
+}
+
+type handler struct {
+	transport *http2.Transport
+}
+
+func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method == http.MethodConnect {
+		h.handleConnect(w, r)
+	} else {
+		h.handleHTTP(w, r)
+	}
+}
+
+func (h *handler) handleConnect(w http.ResponseWriter, r *http.Request) {
+	pr, pw := io.Pipe()
+
+	defer pr.Close()
+	defer pw.Close()
+
+	r.Body = ioutil.NopCloser(pr)
+	r.URL.Scheme = "https"
+
+	r.Header.Del("proxy-connection")
+
+	resp, err := h.transport.RoundTrip(r)
+	if err != nil {
+		log.Println(err)
+		w.WriteHeader(http.StatusServiceUnavailable)
+		fmt.Fprintf(w, "%s", err)
+		return
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		w.WriteHeader(resp.StatusCode)
+		return
+	}
+
+	c, _, err := w.(http.Hijacker).Hijack()
+	if err != nil {
+		w.WriteHeader(http.StatusServiceUnavailable)
+		fmt.Fprintf(w, "%s", err)
+		return
+	}
+
+	defer c.Close()
+	fmt.Fprintf(c, "%s 200 connection established\r\n\r\n", r.Proto)
+
+	ch := make(chan struct{}, 2)
+
+	go func() {
+		io.Copy(pw, c)
+		ch <- struct{}{}
+	}()
+
+	go func() {
+		io.Copy(c, resp.Body)
+		ch <- struct{}{}
+	}()
+
+	<-ch
+}
+
+func (h *handler) handleHTTP(w http.ResponseWriter, r *http.Request) {
+	resp, err := h.transport.RoundTrip(r)
+	if err != nil {
+		log.Println(err)
+		w.WriteHeader(http.StatusServiceUnavailable)
+		fmt.Fprintf(w, "%s", err)
+		return
+	}
+	defer resp.Body.Close()
+
+	resp.Header.Del("connection")
+
+	hdr := w.Header()
+	for k, v := range resp.Header {
+		for _, v1 := range v {
+			hdr.Add(k, v1)
+		}
+	}
+
+	w.WriteHeader(resp.StatusCode)
+	io.Copy(w, resp.Body)
+}
+
+func newClientConn(host string, port string, hostname string, t *http2.Transport) *clientConn {
+	return &clientConn{
+		host:      host,
+		port:      port,
+		hostname:  hostname,
+		transport: t,
+		lock:      new(sync.Mutex),
+	}
+}
+
+func (p *clientConn) GetClientConn(req *http.Request, addr string) (*http2.ClientConn, error) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+	if p.conn != nil {
+		return p.conn, nil
+	}
+	config := &tls.Config{
+		ServerName: p.hostname,
+		NextProtos: []string{"h2"},
+	}
+
+	conn, err := tls.Dial("tcp", net.JoinHostPort(p.host, p.port), config)
+	if err != nil {
+		log.Println(err)
+		return nil, err
+	}
+	http2conn, err := p.transport.NewClientConn(conn)
+	if err != nil {
+		conn.Close()
+		log.Println(err)
+		return nil, err
+	}
+	p.conn = http2conn
+	return http2conn, err
+}
+
+func (p *clientConn) MarkDead(conn *http2.ClientConn) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+	log.Println("mark dead")
+
+	p.conn = nil
+}
+
+func main() {
+	var addr string
+	var hostname string
+	var listen string
+	flag.StringVar(&addr, "server", "", "server address")
+	flag.StringVar(&hostname, "name", "", "server 's SNI name")
+	flag.StringVar(&listen, "listen", ":8080", "listen address")
+	flag.Parse()
+
+	if addr == "" {
+		fmt.Println("please specify the server address")
+		os.Exit(-1)
+	}
+
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		host = addr
+		port = "443"
+	}
+
+	if hostname == "" {
+		hostname = host
+	}
+
+	transport := &http2.Transport{
+		AllowHTTP: true,
+	}
+
+	p := newClientConn(host, port, hostname, transport)
+	transport.ConnPool = p
+
+	log.Printf("listen on %s", listen)
+	log.Printf("use parent proxy https://%s:%s/", host, port)
+	log.Printf("server SNI name %s", hostname)
+
+	if err := http.ListenAndServe(listen, &handler{transport}); err != nil {
+		log.Fatal(err)
+	}
+}