67 lines
1.8 KiB
Go
67 lines
1.8 KiB
Go
// Copyright (c) 2017 Arista Networks, Inc.
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// Use of this source code is governed by the Apache License 2.0
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// that can be found in the COPYING file.
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package dscp
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import (
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"fmt"
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"net"
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"os"
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"reflect"
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"syscall"
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"golang.org/x/sys/unix"
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)
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// This works for the UNIX implementation of netFD, i.e. not on Windows and Plan9.
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// conn must either implement syscall.Conn or be a TCPListener.
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func setTOS(ip net.IP, conn interface{}, tos byte) error {
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var proto, optname int
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if ip.To4() != nil {
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proto = unix.IPPROTO_IP
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optname = unix.IP_TOS
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} else {
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proto = unix.IPPROTO_IPV6
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optname = unix.IPV6_TCLASS
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}
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switch c := conn.(type) {
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case syscall.Conn:
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return setTOSWithSyscallConn(proto, optname, c, tos)
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case *net.TCPListener:
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// This code is needed to support go1.9. In go1.10
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// *net.TCPListener implements syscall.Conn.
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return setTOSWithTCPListener(proto, optname, c, tos)
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}
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return fmt.Errorf("unsupported connection type: %T", conn)
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}
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func setTOSWithTCPListener(proto, optname int, conn *net.TCPListener, tos byte) error {
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// A kludge for pre-go1.10 to get the fd of a net.TCPListener
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value := reflect.ValueOf(conn)
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netFD := value.Elem().FieldByName("fd").Elem()
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fd := int(netFD.FieldByName("pfd").FieldByName("Sysfd").Int())
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if err := unix.SetsockoptInt(fd, proto, optname, int(tos)); err != nil {
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return os.NewSyscallError("setsockopt", err)
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}
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return nil
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}
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func setTOSWithSyscallConn(proto, optname int, conn syscall.Conn, tos byte) error {
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syscallConn, err := conn.SyscallConn()
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if err != nil {
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return err
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}
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var setsockoptErr error
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err = syscallConn.Control(func(fd uintptr) {
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if err := unix.SetsockoptInt(int(fd), proto, optname, int(tos)); err != nil {
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setsockoptErr = os.NewSyscallError("setsockopt", err)
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}
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})
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if setsockoptErr != nil {
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return setsockoptErr
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}
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return err
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}
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