Initial commit

proxy.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/http/httputil"
+)
+
+// Proxy is used to forward HTTP requests.
+type Proxy struct {
+	rp httputil.ReverseProxy
+}
+
+// NewProxy returns a new Proxy.
+func NewProxy() *Proxy {
+	return &Proxy{
+		rp: httputil.ReverseProxy{
+			Director: func(r *http.Request) {
+				log.Printf("Director handled URL: %v", r.URL)
+			},
+		},
+	}
+}
+
+func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	log.Printf("ServeHTTP: Received request (host: %v, url: %v", r.Host, r.URL)
+
+	if r.Method == http.MethodConnect {
+		p.handleConnect(w, r)
+		return
+	}
+
+	p.rp.ServeHTTP(w, r)
+	log.Printf("ServeHTTP: Finished (host: %v, url: %v", r.Host, r.URL)
+}
+
+func (p *Proxy) handleConnect(w http.ResponseWriter, r *http.Request) {
+	hj, ok := w.(http.Hijacker)
+	if !ok {
+		log.Printf("handleConnect: ResponseWriter is not a http.Hijacker (type: %T)", w)
+		writeError(w, r, http.StatusServiceUnavailable)
+		return
+	}
+
+	// destConn is the TCP connection to the destination web server of the
+	// proxied HTTP request.
+	destConn, err := net.Dial("tcp", r.Host)
+	if err != nil {
+		log.Printf("handleConnect: Connect to destination host failed: %v", err)
+		writeError(w, r, http.StatusBadGateway)
+		return
+	}
+	defer destConn.Close()
+
+	w.WriteHeader(http.StatusOK)
+
+	// clientConn is the TCP connection to the client.
+	clientConn, _, err := hj.Hijack()
+	if err != nil {
+		log.Printf("handleConnect: Hijack failed: %v", err)
+		writeError(w, r, http.StatusServiceUnavailable)
+		return
+	}
+	defer clientConn.Close()
+
+	errc := make(chan error, 1)
+	go tunnelData(destConn, clientConn, errc)
+	go tunnelData(clientConn, destConn, errc)
+	<-errc
+}
+
+func tunnelData(dst, src io.ReadWriter, errc chan<- error) {
+	_, err := io.Copy(dst, src)
+	errc <- err
+}
+
+func writeError(w http.ResponseWriter, r *http.Request, code int) {
+	http.Error(w, http.StatusText(code), code)
+}