From d6a6e0aaf8eb366e1158e3684e78b52ae74bbaba Mon Sep 17 00:00:00 2001
From: Darien Raymond <admin@v2ray.com>
Date: Wed, 14 Dec 2016 12:25:22 +0100
Subject: [PATCH] send back http response on error

---
 tools/conf/transport_authenticators.go  |  4 ++
 transport/internet/headers/http/http.go | 71 +++++++++++++++++++------
 2 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/tools/conf/transport_authenticators.go b/tools/conf/transport_authenticators.go
index 895ce22a..768292d4 100644
--- a/tools/conf/transport_authenticators.go
+++ b/tools/conf/transport_authenticators.go
@@ -124,6 +124,10 @@ func (v *HTTPAuthenticatorResponse) Build() (*http.ResponseConfig, error) {
 				Name:  "Pragma",
 				Value: []string{"no-cache"},
 			},
+			{
+				Name:  "Cache-Control",
+				Value: []string{"private", "no-cache"},
+			},
 		},
 	}
 
diff --git a/transport/internet/headers/http/http.go b/transport/internet/headers/http/http.go
index d0ce52ad..8b85d23e 100644
--- a/transport/internet/headers/http/http.go
+++ b/transport/internet/headers/http/http.go
@@ -97,13 +97,15 @@ type HttpConn struct {
 	readBuffer    *buf.Buffer
 	oneTimeReader Reader
 	oneTimeWriter Writer
+	isServer      bool
 }
 
-func NewHttpConn(conn net.Conn, reader Reader, writer Writer) *HttpConn {
+func NewHttpConn(conn net.Conn, reader Reader, writer Writer, isServer bool) *HttpConn {
 	return &HttpConn{
 		Conn:          conn,
 		oneTimeReader: reader,
 		oneTimeWriter: writer,
+		isServer:      isServer,
 	}
 }
 
@@ -141,14 +143,43 @@ func (v *HttpConn) Write(b []byte) (int, error) {
 	return v.Conn.Write(b)
 }
 
-type HttpAuthenticator struct {
-	config *Config
+// Close implements net.Conn.Close().
+func (v *HttpConn) Close() error {
+	if v.isServer && v.oneTimeWriter != nil {
+		// Connection is being closed but header wasn't sent. This means the client request
+		// is probably not valid. Sending back a server error header in this case.
+		writer := formResponseHeader(&ResponseConfig{
+			Version: &Version{
+				Value: "1.1",
+			},
+			Status: &Status{
+				Code:   "500",
+				Reason: "Internal Server Error",
+			},
+			Header: []*Header{
+				{
+					Name:  "Connection",
+					Value: []string{"close"},
+				},
+				{
+					Name:  "Cache-Control",
+					Value: []string{"private"},
+				},
+				{
+					Name:  "Content-Length",
+					Value: []string{"0"},
+				},
+			},
+		})
+		writer.Write(v.Conn)
+	}
+
+	return v.Conn.Close()
 }
 
-func (v HttpAuthenticator) GetClientWriter() *HeaderWriter {
+func formResponseHeader(config *ResponseConfig) *HeaderWriter {
 	header := buf.NewSmall()
-	config := v.config.Request
-	header.AppendSupplier(serial.WriteString(strings.Join([]string{config.Method.GetValue(), config.PickUri(), config.GetFullVersion()}, " ")))
+	header.AppendSupplier(serial.WriteString(strings.Join([]string{config.GetFullVersion(), config.Status.GetCode(), config.Status.GetReason()}, " ")))
 	header.AppendSupplier(writeCRLF)
 
 	headers := config.PickHeaders()
@@ -156,16 +187,25 @@ func (v HttpAuthenticator) GetClientWriter() *HeaderWriter {
 		header.AppendSupplier(serial.WriteString(h))
 		header.AppendSupplier(writeCRLF)
 	}
+	if !config.HasHeader("Date") {
+		header.AppendSupplier(serial.WriteString("Date: "))
+		header.AppendSupplier(serial.WriteString(time.Now().Format(http.TimeFormat)))
+		header.AppendSupplier(writeCRLF)
+	}
 	header.AppendSupplier(writeCRLF)
 	return &HeaderWriter{
 		header: header,
 	}
 }
 
-func (v HttpAuthenticator) GetServerWriter() *HeaderWriter {
+type HttpAuthenticator struct {
+	config *Config
+}
+
+func (v HttpAuthenticator) GetClientWriter() *HeaderWriter {
 	header := buf.NewSmall()
-	config := v.config.Response
-	header.AppendSupplier(serial.WriteString(strings.Join([]string{config.GetFullVersion(), config.Status.GetCode(), config.Status.GetReason()}, " ")))
+	config := v.config.Request
+	header.AppendSupplier(serial.WriteString(strings.Join([]string{config.Method.GetValue(), config.PickUri(), config.GetFullVersion()}, " ")))
 	header.AppendSupplier(writeCRLF)
 
 	headers := config.PickHeaders()
@@ -173,17 +213,16 @@ func (v HttpAuthenticator) GetServerWriter() *HeaderWriter {
 		header.AppendSupplier(serial.WriteString(h))
 		header.AppendSupplier(writeCRLF)
 	}
-	if !config.HasHeader("Date") {
-		header.AppendSupplier(serial.WriteString("Date: "))
-		header.AppendSupplier(serial.WriteString(time.Now().Format(http.TimeFormat)))
-		header.AppendSupplier(writeCRLF)
-	}
 	header.AppendSupplier(writeCRLF)
 	return &HeaderWriter{
 		header: header,
 	}
 }
 
+func (v HttpAuthenticator) GetServerWriter() *HeaderWriter {
+	return formResponseHeader(v.config.Response)
+}
+
 func (v HttpAuthenticator) Client(conn net.Conn) net.Conn {
 	if v.config.Request == nil && v.config.Response == nil {
 		return conn
@@ -197,14 +236,14 @@ func (v HttpAuthenticator) Client(conn net.Conn) net.Conn {
 	if v.config.Response != nil {
 		writer = v.GetClientWriter()
 	}
-	return NewHttpConn(conn, reader, writer)
+	return NewHttpConn(conn, reader, writer, false)
 }
 
 func (v HttpAuthenticator) Server(conn net.Conn) net.Conn {
 	if v.config.Request == nil && v.config.Response == nil {
 		return conn
 	}
-	return NewHttpConn(conn, new(HeaderReader), v.GetServerWriter())
+	return NewHttpConn(conn, new(HeaderReader), v.GetServerWriter(), true)
 }
 
 type HttpAuthenticatorFactory struct{}