add probing resistance support for HTTP2 proxy

gost.go

@@ -7,6 +7,7 @@ import (
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
+	"io"
 	"math/big"
 	"time"
 
@@ -100,3 +101,16 @@ func generateKeyPair() (rawCert, rawKey []byte, err error) {
 
 	return
 }
+
+type readWriter struct {
+	r io.Reader
+	w io.Writer
+}
+
+func (rw *readWriter) Read(p []byte) (n int, err error) {
+	return rw.r.Read(p)
+}
+
+func (rw *readWriter) Write(p []byte) (n int, err error) {
+	return rw.w.Write(p)
+}

http.go

@@ -175,10 +175,12 @@ func (h *httpHandler) handleRequest(conn net.Conn, req *http.Request) {
 			case "host":
 				cc, err := net.Dial("tcp", ss[1])
 				if err == nil {
+					defer cc.Close()
+
 					req.Write(cc)
-					log.Logf("[http] %s <-> %s", conn.LocalAddr(), ss[1])
+					log.Logf("[http] %s <-> %s : forward to %s", conn.LocalAddr(), req.Host, ss[1])
 					transport(conn, cc)
-					log.Logf("[http] %s >-< %s", conn.LocalAddr(), ss[1])
+					log.Logf("[http] %s >-< %s : forward to %s", conn.LocalAddr(), req.Host, ss[1])
 					return
 				}
 			case "file":

http2.go

@@ -2,14 +2,18 @@ package gost
 
 import (
 	"bufio"
+	"bytes"
 	"crypto/tls"
 	"encoding/base64"
 	"errors"
 	"io"
+	"io/ioutil"
 	"net"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
+	"os"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -308,14 +312,79 @@ func (h *http2Handler) roundTrip(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	resp := &http.Response{
+		ProtoMajor: 2,
+		ProtoMinor: 0,
+		Header:     http.Header{},
+		Body:       ioutil.NopCloser(bytes.NewReader([]byte{})),
+	}
+
 	u, p, _ := basicProxyAuth(r.Header.Get("Proxy-Authorization"))
 	if Debug && (u != "" || p != "") {
 		log.Logf("[http] %s - %s : Authorization: '%s' '%s'", r.RemoteAddr, target, u, p)
 	}
 	if !authenticate(u, p, h.options.Users...) {
-		log.Logf("[http2] %s <- %s : proxy authentication required", r.RemoteAddr, target)
-		w.Header().Set("Proxy-Authenticate", "Basic realm=\"gost\"")
-		w.WriteHeader(http.StatusProxyAuthRequired)
+		// probing resistance is enabled
+		if ss := strings.SplitN(h.options.ProbeResist, ":", 2); len(ss) == 2 {
+			switch ss[0] {
+			case "error":
+				resp.StatusCode, _ = strconv.Atoi(ss[1])
+			case "web":
+				url := ss[1]
+				if !strings.HasPrefix(url, "http") {
+					url = "http://" + url
+				}
+				if r, err := http.Get(url); err == nil {
+					resp = r
+				}
+			case "host":
+				cc, err := net.Dial("tcp", ss[1])
+				if err == nil {
+					defer cc.Close()
+					log.Logf("[http2] %s <-> %s : forward to %s", r.RemoteAddr, target, ss[1])
+					if err := h.forwardRequest(w, r, cc); err != nil {
+						log.Logf("[http2] %s - %s : %s", r.RemoteAddr, target, err)
+					}
+					log.Logf("[http2] %s >-< %s : forward to %s", r.RemoteAddr, target, ss[1])
+					return
+				}
+			case "file":
+				f, _ := os.Open(ss[1])
+				if f != nil {
+					resp.StatusCode = http.StatusOK
+					if finfo, _ := f.Stat(); finfo != nil {
+						resp.ContentLength = finfo.Size()
+					}
+					resp.Body = f
+				}
+			}
+		}
+
+		if resp.StatusCode == 0 {
+			log.Logf("[http2] %s <- %s : proxy authentication required", r.RemoteAddr, target)
+			resp.StatusCode = http.StatusProxyAuthRequired
+			resp.Header.Add("Proxy-Authenticate", "Basic realm=\"gost\"")
+		} else {
+			w.Header().Del("Proxy-Agent")
+			resp.Header = http.Header{}
+			resp.Header.Set("Server", "nginx/1.14.1")
+			resp.Header.Set("Date", time.Now().Format(http.TimeFormat))
+			if resp.ContentLength > 0 {
+				resp.Header.Set("Content-Type", "text/html")
+			}
+			if resp.StatusCode == http.StatusOK {
+				resp.Header.Set("Connection", "keep-alive")
+			}
+		}
+
+		if Debug {
+			dump, _ := httputil.DumpResponse(resp, false)
+			log.Logf("[http2] %s <- %s\n%s", r.RemoteAddr, target, string(dump))
+		}
+
+		h.writeResponse(w, resp)
+		resp.Body.Close()
+
 		return
 	}
 
@@ -359,47 +428,41 @@ func (h *http2Handler) roundTrip(w http.ResponseWriter, r *http.Request) {
 		}
 
 		log.Logf("[http2] %s <-> %s", r.RemoteAddr, target)
-		errc := make(chan error, 2)
-		go func() {
-			_, err := io.Copy(cc, r.Body)
-			errc <- err
-		}()
-		go func() {
-			_, err := io.Copy(flushWriter{w}, cc)
-			errc <- err
-		}()
-
-		select {
-		case <-errc:
-			// glog.V(LWARNING).Infoln("exit", err)
-		}
+		transport(&readWriter{r: r.Body, w: flushWriter{w}}, cc)
 		log.Logf("[http2] %s >-< %s", r.RemoteAddr, target)
 		return
 	}
 
 	log.Logf("[http2] %s <-> %s", r.RemoteAddr, target)
-	if err = r.Write(cc); err != nil {
-		log.Logf("[http2] %s -> %s : %s", r.RemoteAddr, target, err)
+	if err := h.forwardRequest(w, r, cc); err != nil {
+		log.Logf("[http2] %s - %s : %s", r.RemoteAddr, target, err)
+	}
+	log.Logf("[http2] %s >-< %s", r.RemoteAddr, target)
+}
+
+func (h *http2Handler) forwardRequest(w http.ResponseWriter, r *http.Request, rw io.ReadWriter) (err error) {
+	if err = r.Write(rw); err != nil {
 		return
 	}
 
-	resp, err := http.ReadResponse(bufio.NewReader(cc), r)
+	resp, err := http.ReadResponse(bufio.NewReader(rw), r)
 	if err != nil {
-		log.Logf("[http2] %s -> %s : %s", r.RemoteAddr, target, err)
 		return
 	}
 	defer resp.Body.Close()
 
+	return h.writeResponse(w, resp)
+}
+
+func (h *http2Handler) writeResponse(w http.ResponseWriter, resp *http.Response) error {
 	for k, v := range resp.Header {
 		for _, vv := range v {
 			w.Header().Add(k, vv)
 		}
 	}
 	w.WriteHeader(resp.StatusCode)
-	if _, err := io.Copy(flushWriter{w}, resp.Body); err != nil {
-		log.Logf("[http2] %s <- %s : %s", r.RemoteAddr, target, err)
-	}
-	log.Logf("[http2] %s >-< %s", r.RemoteAddr, target)
+	_, err := io.Copy(flushWriter{w}, resp.Body)
+	return err
 }
 
 type http2Listener struct {