42 lines
1.2 KiB
Go
42 lines
1.2 KiB
Go
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// Copyright 2014 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 icmp
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// A PacketTooBig represents an ICMP packet too big message body.
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type PacketTooBig struct {
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MTU int // maximum transmission unit of the nexthop link
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Data []byte // data, known as original datagram field
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}
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// Len implements the Len method of MessageBody interface.
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func (p *PacketTooBig) Len(proto int) int {
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if p == nil {
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return 0
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}
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return 4 + len(p.Data)
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}
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// Marshal implements the Marshal method of MessageBody interface.
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func (p *PacketTooBig) Marshal(proto int) ([]byte, error) {
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b := make([]byte, 4+len(p.Data))
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b[0], b[1], b[2], b[3] = byte(p.MTU>>24), byte(p.MTU>>16), byte(p.MTU>>8), byte(p.MTU)
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copy(b[4:], p.Data)
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return b, nil
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}
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// parsePacketTooBig parses b as an ICMP packet too big message body.
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func parsePacketTooBig(proto int, b []byte) (MessageBody, error) {
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bodyLen := len(b)
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if bodyLen < 4 {
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return nil, errMessageTooShort
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}
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p := &PacketTooBig{MTU: int(b[0])<<24 | int(b[1])<<16 | int(b[2])<<8 | int(b[3])}
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if bodyLen > 4 {
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p.Data = make([]byte, bodyLen-4)
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copy(p.Data, b[4:])
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}
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return p, nil
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}
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