Set HTTP upgrade header only when requested by client

Signed-off-by: Jean-Tiare Le Bigot <jt@yadutaf.fr>

api/server/server.go

@@ -887,7 +887,11 @@ func postContainersAttach(eng *engine.Engine, version version.Version, w http.Re
 
 	var errStream io.Writer
 
-	fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")
+	if _, ok := r.Header["Upgrade"]; ok {
+		fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")
+	} else {
+		fmt.Fprintf(outStream, "HTTP/1.1 200 OK\r\nContent-Type: application/vnd.docker.raw-stream\r\n\r\n")
+	}
 
 	if c.GetSubEnv("Config") != nil && !c.GetSubEnv("Config").GetBool("Tty") && version.GreaterThanOrEqualTo("1.6") {
 		errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr)
@@ -1137,7 +1141,12 @@ func postContainerExecStart(eng *engine.Engine, version version.Version, w http.
 
 		var errStream io.Writer
 
-		fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")
+		if _, ok := r.Header["Upgrade"]; ok {
+			fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")
+		} else {
+			fmt.Fprintf(outStream, "HTTP/1.1 200 OK\r\nContent-Type: application/vnd.docker.raw-stream\r\n\r\n")
+		}
+
 		if !job.GetenvBool("Tty") && version.GreaterThanOrEqualTo("1.6") {
 			errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr)
 			outStream = stdcopy.NewStdWriter(outStream, stdcopy.Stdout)