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https://github.com/tailscale/tailscale.git
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55b1221db2
The packet filter still rejects all IPv6, but decodes enough from v6 packets to do something smarter in a followup. name time/op Decode/tcp4-8 28.8ns ± 2% Decode/tcp6-8 20.6ns ± 1% Decode/udp4-8 28.2ns ± 1% Decode/udp6-8 20.0ns ± 6% Decode/icmp4-8 21.7ns ± 2% Decode/icmp6-8 14.1ns ± 2% Decode/unknown-8 9.43ns ± 2% Signed-off-by: David Anderson <danderson@tailscale.com>
81 lines
1.6 KiB
Go
81 lines
1.6 KiB
Go
// Copyright (c) 2020 Tailscale Inc & 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 packet
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type ICMP4Type uint8
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const (
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ICMP4EchoReply ICMP4Type = 0x00
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ICMP4EchoRequest ICMP4Type = 0x08
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ICMP4Unreachable ICMP4Type = 0x03
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ICMP4TimeExceeded ICMP4Type = 0x0b
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)
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func (t ICMP4Type) String() string {
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switch t {
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case ICMP4EchoReply:
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return "EchoReply"
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case ICMP4EchoRequest:
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return "EchoRequest"
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case ICMP4Unreachable:
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return "Unreachable"
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case ICMP4TimeExceeded:
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return "TimeExceeded"
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default:
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return "Unknown"
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}
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}
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type ICMP4Code uint8
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const (
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ICMP4NoCode ICMP4Code = 0
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)
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// ICMP4Header represents an ICMPv4 packet header.
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type ICMP4Header struct {
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IP4Header
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Type ICMP4Type
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Code ICMP4Code
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}
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const (
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icmp4HeaderLength = 4
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// icmp4AllHeadersLength is the length of all headers in a ICMPv4 packet.
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icmp4AllHeadersLength = ip4HeaderLength + icmp4HeaderLength
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)
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func (ICMP4Header) Len() int {
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return icmp4AllHeadersLength
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}
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func (h ICMP4Header) Marshal(buf []byte) error {
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if len(buf) < icmp4AllHeadersLength {
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return errSmallBuffer
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}
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if len(buf) > maxPacketLength {
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return errLargePacket
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}
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// The caller does not need to set this.
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h.IPProto = ICMPv4
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buf[20] = uint8(h.Type)
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buf[21] = uint8(h.Code)
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h.IP4Header.Marshal(buf)
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put16(buf[22:24], ipChecksum(buf))
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return nil
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}
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func (h *ICMP4Header) ToResponse() {
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// TODO: this doesn't implement ToResponse correctly, as it
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// assumes the ICMP request type.
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h.Type = ICMP4EchoReply
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h.Code = ICMP4NoCode
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h.IP4Header.ToResponse()
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}
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