From 7a2769621bd654b26cd157774a79ebe2892bff91 Mon Sep 17 00:00:00 2001
From: gVisor bot <gvisor-bot@google.com>
Date: Mon, 20 Dec 2021 12:59:06 +0800
Subject: [PATCH] Update vless.go

---
 adapter/outbound/vless.go | 85 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 80 insertions(+), 5 deletions(-)

diff --git a/adapter/outbound/vless.go b/adapter/outbound/vless.go
index 01d161ec..3dac52da 100644
--- a/adapter/outbound/vless.go
+++ b/adapter/outbound/vless.go
@@ -3,11 +3,13 @@ package outbound
 import (
 	"context"
 	"crypto/tls"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"net"
 	"net/http"
 	"strconv"
+	"sync"
 
 	"github.com/Dreamacro/clash/component/dialer"
 	"github.com/Dreamacro/clash/component/resolver"
@@ -18,6 +20,11 @@ import (
 	"golang.org/x/net/http2"
 )
 
+const (
+	// max packet length
+	maxLength = 8192
+)
+
 type Vless struct {
 	*Base
 	client *vless.Client
@@ -280,17 +287,85 @@ func parseVlessAddr(metadata *C.Metadata) *vless.DstAddr {
 type vlessPacketConn struct {
 	net.Conn
 	rAddr net.Addr
+	remain int
+	mux    sync.Mutex
+	cache  []byte
 }
 
-func (uc *vlessPacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
-	return uc.Conn.Write(b)
+func (c *vlessPacketConn) writePacket(b []byte, addr net.Addr) (int, error) {
+	length := len(b)
+	defer func() {
+		c.cache = c.cache[:0]
+	}()
+	c.cache = append(c.cache, byte(length>>8), byte(length))
+	c.cache = append(c.cache, b...)
+	n, err := c.Conn.Write(c.cache)
+	if n > 2 {
+		return n - 2, err
+	}
+
+	return 0, err
 }
 
-func (uc *vlessPacketConn) ReadFrom(b []byte) (int, net.Addr, error) {
-	n, err := uc.Conn.Read(b)
-	return n, uc.rAddr, err
+func (c *vlessPacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
+	if len(b) <= maxLength {
+		return c.writePacket(b, addr)
+	}
+
+	offset := 0
+	total := len(b)
+	for offset < total {
+		cursor := offset + maxLength
+		if cursor > total {
+			cursor = total
+		}
+
+		n, err := c.writePacket(b[offset:cursor], addr)
+		if err != nil {
+			return offset + n, err
+		}
+
+		offset = cursor
+	}
+
+	return total, nil
 }
 
+
+func (c *vlessPacketConn) ReadFrom(b []byte) (int, net.Addr, error) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+
+	length := len(b)
+	if c.remain > 0 {
+		if c.remain < length {
+			length = c.remain
+		}
+
+		n, err := c.Conn.Read(b[:length])
+		if err != nil {
+			return 0, nil, err
+		}
+
+		c.remain -= n
+		return n, c.rAddr, nil
+	}
+
+	var packetLength uint16
+	if err := binary.Read(c.Conn, binary.BigEndian, &packetLength); err != nil {
+		return 0, nil, err
+	}
+
+	remain := int(packetLength)
+	n, err := c.Conn.Read(b[:length])
+	remain -= n
+	if remain > 0 {
+		c.remain = remain
+	}
+	return n, c.rAddr, err
+}
+
+
 func NewVless(option VlessOption) (*Vless, error) {
 	if !option.TLS && option.Network == "grpc" {
 		return nil, fmt.Errorf("TLS must be true with vless-grpc")