Fix: http proxy Upgrade behavior (#2097)

listener/http/proxy.go

@@ -19,12 +19,7 @@ func HandleConn(c net.Conn, in chan<- C.ConnContext, cache *cache.Cache[string,
 	client := newClient(c.RemoteAddr(), in)
 	defer client.CloseIdleConnections()
 
-	var conn *N.BufferedConn
-	if bufConn, ok := c.(*N.BufferedConn); ok {
-		conn = bufConn
-	} else {
-		conn = N.NewBufferedConn(c)
-	}
+	conn := N.NewBufferedConn(c)
 
 	keepAlive := true
 	trusted := cache == nil // disable authenticate if cache is nil
@@ -66,6 +61,12 @@ func HandleConn(c net.Conn, in chan<- C.ConnContext, cache *cache.Cache[string,
 
 			request.RequestURI = ""
 
+			if isUpgradeRequest(request) {
+				handleUpgrade(conn, request, in)
+
+				return // hijack connection
+			}
+
 			removeHopByHopHeaders(request.Header)
 			removeExtraHTTPHostPort(request)
 

listener/http/upgrade.go

@@ -0,0 +1,61 @@
+package http
+
+import (
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/Dreamacro/clash/adapter/inbound"
+	N "github.com/Dreamacro/clash/common/net"
+	C "github.com/Dreamacro/clash/constant"
+	"github.com/Dreamacro/clash/transport/socks5"
+)
+
+func isUpgradeRequest(req *http.Request) bool {
+	return strings.EqualFold(req.Header.Get("Connection"), "Upgrade")
+}
+
+func handleUpgrade(conn net.Conn, request *http.Request, in chan<- C.ConnContext) {
+	defer conn.Close()
+
+	removeProxyHeaders(request.Header)
+	removeExtraHTTPHostPort(request)
+
+	address := request.Host
+	if _, _, err := net.SplitHostPort(address); err != nil {
+		address = net.JoinHostPort(address, "80")
+	}
+
+	dstAddr := socks5.ParseAddr(address)
+	if dstAddr == nil {
+		return
+	}
+
+	left, right := net.Pipe()
+
+	in <- inbound.NewHTTP(dstAddr, conn.RemoteAddr(), right)
+
+	bufferedLeft := N.NewBufferedConn(left)
+	defer bufferedLeft.Close()
+
+	err := request.Write(bufferedLeft)
+	if err != nil {
+		return
+	}
+
+	resp, err := http.ReadResponse(bufferedLeft.Reader(), request)
+	if err != nil {
+		return
+	}
+
+	removeProxyHeaders(resp.Header)
+
+	err = resp.Write(conn)
+	if err != nil {
+		return
+	}
+
+	if resp.StatusCode == http.StatusSwitchingProtocols {
+		N.Relay(bufferedLeft, conn)
+	}
+}

listener/http/utils.go

@@ -8,15 +8,21 @@ import (
 	"strings"
 )
 
+// removeHopByHopHeaders remove Proxy-* headers
+func removeProxyHeaders(header http.Header) {
+	header.Del("Proxy-Connection")
+	header.Del("Proxy-Authenticate")
+	header.Del("Proxy-Authorization")
+}
+
 // removeHopByHopHeaders remove hop-by-hop header
 func removeHopByHopHeaders(header http.Header) {
 	// Strip hop-by-hop header based on RFC:
 	// http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.5.1
 	// https://www.mnot.net/blog/2011/07/11/what_proxies_must_do
 
-	header.Del("Proxy-Connection")
-	header.Del("Proxy-Authenticate")
-	header.Del("Proxy-Authorization")
+	removeProxyHeaders(header)
+
 	header.Del("TE")
 	header.Del("Trailers")
 	header.Del("Transfer-Encoding")