74 lines
2.1 KiB
Go
74 lines
2.1 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package header
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const (
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typeHLen = 0
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encapProto = 1
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)
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// GUEFields contains the fields of a GUE packet. It is used to describe the
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// fields of a packet that needs to be encoded.
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type GUEFields struct {
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// Type is the "type" field of the GUE header.
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Type uint8
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// Control is the "control" field of the GUE header.
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Control bool
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// HeaderLength is the "header length" field of the GUE header. It must
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// be at least 4 octets, and a multiple of 4 as well.
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HeaderLength uint8
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// Protocol is the "protocol" field of the GUE header. This is one of
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// the IPPROTO_* values.
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Protocol uint8
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}
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// GUE represents a Generic UDP Encapsulation header stored in a byte array, the
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// fields are described in https://tools.ietf.org/html/draft-ietf-nvo3-gue-01.
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type GUE []byte
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const (
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// GUEMinimumSize is the minimum size of a valid GUE packet.
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GUEMinimumSize = 4
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)
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// TypeAndControl returns the GUE packet type (top 3 bits of the first byte,
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// which includes the control bit).
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func (b GUE) TypeAndControl() uint8 {
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return b[typeHLen] >> 5
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}
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// HeaderLength returns the total length of the GUE header.
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func (b GUE) HeaderLength() uint8 {
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return 4 + 4*(b[typeHLen]&0x1f)
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}
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// Protocol returns the protocol field of the GUE header.
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func (b GUE) Protocol() uint8 {
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return b[encapProto]
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}
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// Encode encodes all the fields of the GUE header.
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func (b GUE) Encode(i *GUEFields) {
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ctl := uint8(0)
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if i.Control {
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ctl = 1 << 5
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}
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b[typeHLen] = ctl | i.Type<<6 | (i.HeaderLength-4)/4
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b[encapProto] = i.Protocol
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}
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