Add openvpn and openconnect

protocol/openvpn/socket_buffer_linux.go

@@ -0,0 +1,28 @@
+package openvpn
+
+import (
+	"syscall"
+
+	"github.com/sagernet/sing/common"
+
+	"golang.org/x/sys/unix"
+)
+
+const openVPNUDPSocketBufferSize = 7 << 20
+
+func tuneOpenVPNUDPSocket(connection any) {
+	syscallConnection, loaded := common.Cast[syscall.Conn](connection)
+	if !loaded {
+		return
+	}
+	rawConnection, err := syscallConnection.SyscallConn()
+	if err != nil {
+		return
+	}
+	_ = rawConnection.Control(func(fd uintptr) {
+		_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_RCVBUF, openVPNUDPSocketBufferSize)
+		_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_SNDBUF, openVPNUDPSocketBufferSize)
+		_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_RCVBUFFORCE, openVPNUDPSocketBufferSize)
+		_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_SNDBUFFORCE, openVPNUDPSocketBufferSize)
+	})
+}