70 lines
2.2 KiB
Go
70 lines
2.2 KiB
Go
// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ipv4
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import (
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"fmt"
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"net"
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"sync"
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)
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type rawOpt struct {
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sync.RWMutex
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cflags ControlFlags
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}
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func (c *rawOpt) set(f ControlFlags) { c.cflags |= f }
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func (c *rawOpt) clear(f ControlFlags) { c.cflags &^= f }
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func (c *rawOpt) isset(f ControlFlags) bool { return c.cflags&f != 0 }
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type ControlFlags uint
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const (
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FlagTTL ControlFlags = 1 << iota // pass the TTL on the received packet
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FlagSrc // pass the source address on the received packet
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FlagDst // pass the destination address on the received packet
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FlagInterface // pass the interface index on the received packet
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)
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// A ControlMessage represents per packet basis IP-level socket options.
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type ControlMessage struct {
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// Receiving socket options: SetControlMessage allows to
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// receive the options from the protocol stack using ReadFrom
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// method of PacketConn or RawConn.
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//
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// Specifying socket options: ControlMessage for WriteTo
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// method of PacketConn or RawConn allows to send the options
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// to the protocol stack.
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//
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TTL int // time-to-live, receiving only
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Src net.IP // source address, specifying only
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Dst net.IP // destination address, receiving only
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IfIndex int // interface index, must be 1 <= value when specifying
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}
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func (cm *ControlMessage) String() string {
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if cm == nil {
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return "<nil>"
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}
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return fmt.Sprintf("ttl=%d src=%v dst=%v ifindex=%d", cm.TTL, cm.Src, cm.Dst, cm.IfIndex)
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}
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// Ancillary data socket options
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const (
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ctlTTL = iota // header field
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ctlSrc // header field
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ctlDst // header field
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ctlInterface // inbound or outbound interface
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ctlPacketInfo // inbound or outbound packet path
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ctlMax
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)
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// A ctlOpt represents a binding for ancillary data socket option.
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type ctlOpt struct {
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name int // option name, must be equal or greater than 1
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length int // option length
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marshal func([]byte, *ControlMessage) []byte
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parse func(*ControlMessage, []byte)
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}
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