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71029cea2d
This updates all source files to use a new standard header for copyright and license declaration. Notably, copyright no longer includes a date, and we now use the standard SPDX-License-Identifier header. This commit was done almost entirely mechanically with perl, and then some minimal manual fixes. Updates #6865 Signed-off-by: Will Norris <will@tailscale.com>
77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package packet
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import (
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"encoding/binary"
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"net/netip"
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"tailscale.com/types/ipproto"
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)
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// ip6HeaderLength is the length of an IPv6 header with no IP options.
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const ip6HeaderLength = 40
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// IP6Header represents an IPv6 packet header.
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type IP6Header struct {
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IPProto ipproto.Proto
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IPID uint32 // only lower 20 bits used
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Src netip.Addr
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Dst netip.Addr
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}
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// Len implements Header.
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func (h IP6Header) Len() int {
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return ip6HeaderLength
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}
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// Marshal implements Header.
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func (h IP6Header) Marshal(buf []byte) error {
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if len(buf) < h.Len() {
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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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binary.BigEndian.PutUint32(buf[:4], h.IPID&0x000FFFFF)
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buf[0] = 0x60
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binary.BigEndian.PutUint16(buf[4:6], uint16(len(buf)-ip6HeaderLength)) // Total length
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buf[6] = uint8(h.IPProto) // Inner protocol
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buf[7] = 64 // TTL
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src, dst := h.Src.As16(), h.Dst.As16()
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copy(buf[8:24], src[:])
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copy(buf[24:40], dst[:])
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return nil
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}
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// ToResponse implements Header.
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func (h *IP6Header) ToResponse() {
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h.Src, h.Dst = h.Dst, h.Src
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// Flip the bits in the IPID. If incoming IPIDs are distinct, so are these.
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h.IPID = (^h.IPID) & 0x000FFFFF
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}
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// marshalPseudo serializes h into buf in the "pseudo-header" form
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// required when calculating UDP checksums.
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func (h IP6Header) marshalPseudo(buf []byte, proto ipproto.Proto) error {
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if len(buf) < h.Len() {
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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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src, dst := h.Src.As16(), h.Dst.As16()
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copy(buf[:16], src[:])
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copy(buf[16:32], dst[:])
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binary.BigEndian.PutUint32(buf[32:36], uint32(len(buf)-h.Len()))
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buf[36] = 0
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buf[37] = 0
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buf[38] = 0
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buf[39] = byte(proto) // NextProto
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return nil
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}
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