From 5341365bb80f24e199888ec836dc2d41445479dd Mon Sep 17 00:00:00 2001
From: H1JK <hell0jack@protonmail.com>
Date: Sat, 13 Apr 2024 12:21:01 +0800
Subject: [PATCH] Add v2ray httpupgrade fast open support

---
 option/v2ray_transport.go            |  7 +--
 transport/v2rayhttpupgrade/client.go | 67 +++++++++++++++++++++++++++-
 2 files changed, 70 insertions(+), 4 deletions(-)

diff --git a/option/v2ray_transport.go b/option/v2ray_transport.go
index fcd81f94..99d0328b 100644
--- a/option/v2ray_transport.go
+++ b/option/v2ray_transport.go
@@ -92,7 +92,8 @@ type V2RayGRPCOptions struct {
 }
 
 type V2RayHTTPUpgradeOptions struct {
-	Host    string     `json:"host,omitempty"`
-	Path    string     `json:"path,omitempty"`
-	Headers HTTPHeader `json:"headers,omitempty"`
+	Host     string     `json:"host,omitempty"`
+	Path     string     `json:"path,omitempty"`
+	Headers  HTTPHeader `json:"headers,omitempty"`
+	FastOpen bool       `json:"fast_open,omitempty"`
 }
diff --git a/transport/v2rayhttpupgrade/client.go b/transport/v2rayhttpupgrade/client.go
index c10e1b8f..87354ca6 100644
--- a/transport/v2rayhttpupgrade/client.go
+++ b/transport/v2rayhttpupgrade/client.go
@@ -6,11 +6,15 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
+	"sync"
+	"time"
 
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/common/tls"
 	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing/common/atomic"
 	"github.com/sagernet/sing/common/buf"
 	"github.com/sagernet/sing/common/bufio"
 	E "github.com/sagernet/sing/common/exceptions"
@@ -28,6 +32,7 @@ type Client struct {
 	requestURL url.URL
 	headers    http.Header
 	host       string
+	fastOpen   bool
 }
 
 func NewClient(ctx context.Context, dialer N.Dialer, serverAddr M.Socksaddr, options option.V2RayHTTPUpgradeOptions, tlsConfig tls.Config) (*Client, error) {
@@ -70,6 +75,7 @@ func NewClient(ctx context.Context, dialer N.Dialer, serverAddr M.Socksaddr, opt
 		requestURL: requestURL,
 		headers:    headers,
 		host:       host,
+		fastOpen:   options.FastOpen,
 	}, nil
 }
 
@@ -96,8 +102,17 @@ func (c *Client) DialContext(ctx context.Context) (net.Conn, error) {
 	if err != nil {
 		return nil, err
 	}
+	if c.fastOpen {
+		return &EarlyHTTPUpgradeConn{
+			Conn: conn,
+		}, nil
+	}
+	return readResponse(conn)
+}
+
+func readResponse(conn net.Conn) (net.Conn, error) {
 	bufReader := std_bufio.NewReader(conn)
-	response, err := http.ReadResponse(bufReader, request)
+	response, err := http.ReadResponse(bufReader, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -116,3 +131,53 @@ func (c *Client) DialContext(ctx context.Context) (net.Conn, error) {
 	}
 	return conn, nil
 }
+
+type EarlyHTTPUpgradeConn struct {
+	net.Conn
+	once    sync.Once
+	err     error
+	created atomic.Bool
+}
+
+func (c *EarlyHTTPUpgradeConn) Read(b []byte) (int, error) {
+	c.once.Do(func() {
+		var newConn net.Conn
+		newConn, c.err = readResponse(c.Conn)
+		if c.err == nil {
+			c.Conn = newConn
+			c.created.Store(true)
+		}
+	})
+	if c.err != nil {
+		return 0, c.err
+	}
+	return c.Conn.Read(b)
+}
+
+func (c *EarlyHTTPUpgradeConn) Upstream() any {
+	return c.Conn
+}
+
+func (c *EarlyHTTPUpgradeConn) ReaderReplaceable() bool {
+	return c.created.Load()
+}
+
+func (c *EarlyHTTPUpgradeConn) WriterReplaceable() bool {
+	return true
+}
+
+func (c *EarlyHTTPUpgradeConn) SetDeadline(time.Time) error {
+	return os.ErrInvalid
+}
+
+func (c *EarlyHTTPUpgradeConn) SetReadDeadline(time.Time) error {
+	return os.ErrInvalid
+}
+
+func (c *EarlyHTTPUpgradeConn) SetWriteDeadline(time.Time) error {
+	return os.ErrInvalid
+}
+
+func (c *EarlyHTTPUpgradeConn) NeedAdditionalReadDeadline() bool {
+	return true
+}