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tailscale/control/controlbase/messages.go

89 lines
3.2 KiB
Go

// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package controlbase
import "encoding/binary"
const (
// msgTypeInitiation frames carry a Noise IK handshake initiation message.
msgTypeInitiation = 1
// msgTypeResponse frames carry a Noise IK handshake response message.
msgTypeResponse = 2
// msgTypeError frames carry an unauthenticated human-readable
// error message.
//
// Errors reported in this message type must be treated as public
// hints only. They are not encrypted or authenticated, and so can
// be seen and tampered with on the wire.
msgTypeError = 3
// msgTypeRecord frames carry session data bytes.
msgTypeRecord = 4
// headerLen is the size of the header on all messages except msgTypeInitiation.
headerLen = 3
// initiationHeaderLen is the size of the header on all msgTypeInitiation messages.
initiationHeaderLen = 5
)
// initiationMessage is the protocol message sent from a client
// machine to a control server.
//
// 2b: protocol version
// 1b: message type (0x01)
// 2b: payload length (96)
// 5b: header (see headerLen for fields)
// 32b: client ephemeral public key (cleartext)
// 48b: client machine public key (encrypted)
// 16b: message tag (authenticates the whole message)
type initiationMessage [101]byte
func mkInitiationMessage(protocolVersion uint16) initiationMessage {
var ret initiationMessage
binary.BigEndian.PutUint16(ret[:2], protocolVersion)
ret[2] = msgTypeInitiation
binary.BigEndian.PutUint16(ret[3:5], uint16(len(ret.Payload())))
return ret
}
func (m *initiationMessage) Header() []byte { return m[:initiationHeaderLen] }
func (m *initiationMessage) Payload() []byte { return m[initiationHeaderLen:] }
func (m *initiationMessage) Version() uint16 { return binary.BigEndian.Uint16(m[:2]) }
func (m *initiationMessage) Type() byte { return m[2] }
func (m *initiationMessage) Length() int { return int(binary.BigEndian.Uint16(m[3:5])) }
func (m *initiationMessage) EphemeralPub() []byte {
return m[initiationHeaderLen : initiationHeaderLen+32]
}
func (m *initiationMessage) MachinePub() []byte {
return m[initiationHeaderLen+32 : initiationHeaderLen+32+48]
}
func (m *initiationMessage) Tag() []byte { return m[initiationHeaderLen+32+48:] }
// responseMessage is the protocol message sent from a control server
// to a client machine.
//
// 1b: message type (0x02)
// 2b: payload length (48)
// 32b: control ephemeral public key (cleartext)
// 16b: message tag (authenticates the whole message)
type responseMessage [51]byte
func mkResponseMessage() responseMessage {
var ret responseMessage
ret[0] = msgTypeResponse
binary.BigEndian.PutUint16(ret[1:], uint16(len(ret.Payload())))
return ret
}
func (m *responseMessage) Header() []byte { return m[:headerLen] }
func (m *responseMessage) Payload() []byte { return m[headerLen:] }
func (m *responseMessage) Type() byte { return m[0] }
func (m *responseMessage) Length() int { return int(binary.BigEndian.Uint16(m[1:3])) }
func (m *responseMessage) EphemeralPub() []byte { return m[headerLen : headerLen+32] }
func (m *responseMessage) Tag() []byte { return m[headerLen+32:] }