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02ad987e24
This is so that we can plumb our client capability version through the protocol as the Noise version. The capability version increments more frequently than strictly required (the Noise version only needs to change when cryptographically-significant changes are made to the protocol, whereas the capability version also indicates changes in non-cryptographically-significant parts of the protocol), but this gives us a safe pre-auth way to determine if the client supports future protocol features, while still relying on Noise's strong assurance that the client and server have agreed on the same version. Currently, the server executes the same protocol regardless of the version number, and just presents the version to the caller so they can do capability-based things in the upper RPC protocol. In future, we may add a ratchet to disallow obsolete protocols, or vary the Noise handshake behavior based on requested version. Updates #3488 Signed-off-by: David Anderson <danderson@tailscale.com>
89 lines
3.2 KiB
Go
89 lines
3.2 KiB
Go
// Copyright (c) 2021 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 controlbase
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import "encoding/binary"
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const (
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// msgTypeInitiation frames carry a Noise IK handshake initiation message.
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msgTypeInitiation = 1
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// msgTypeResponse frames carry a Noise IK handshake response message.
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msgTypeResponse = 2
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// msgTypeError frames carry an unauthenticated human-readable
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// error message.
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//
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// Errors reported in this message type must be treated as public
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// hints only. They are not encrypted or authenticated, and so can
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// be seen and tampered with on the wire.
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msgTypeError = 3
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// msgTypeRecord frames carry session data bytes.
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msgTypeRecord = 4
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// headerLen is the size of the header on all messages except msgTypeInitiation.
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headerLen = 3
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// initiationHeaderLen is the size of the header on all msgTypeInitiation messages.
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initiationHeaderLen = 5
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)
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// initiationMessage is the protocol message sent from a client
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// machine to a control server.
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//
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// 2b: protocol version
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// 1b: message type (0x01)
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// 2b: payload length (96)
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// 5b: header (see headerLen for fields)
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// 32b: client ephemeral public key (cleartext)
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// 48b: client machine public key (encrypted)
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// 16b: message tag (authenticates the whole message)
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type initiationMessage [101]byte
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func mkInitiationMessage(protocolVersion uint16) initiationMessage {
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var ret initiationMessage
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binary.BigEndian.PutUint16(ret[:2], protocolVersion)
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ret[2] = msgTypeInitiation
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binary.BigEndian.PutUint16(ret[3:5], uint16(len(ret.Payload())))
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return ret
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}
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func (m *initiationMessage) Header() []byte { return m[:initiationHeaderLen] }
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func (m *initiationMessage) Payload() []byte { return m[initiationHeaderLen:] }
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func (m *initiationMessage) Version() uint16 { return binary.BigEndian.Uint16(m[:2]) }
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func (m *initiationMessage) Type() byte { return m[2] }
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func (m *initiationMessage) Length() int { return int(binary.BigEndian.Uint16(m[3:5])) }
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func (m *initiationMessage) EphemeralPub() []byte {
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return m[initiationHeaderLen : initiationHeaderLen+32]
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}
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func (m *initiationMessage) MachinePub() []byte {
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return m[initiationHeaderLen+32 : initiationHeaderLen+32+48]
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}
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func (m *initiationMessage) Tag() []byte { return m[initiationHeaderLen+32+48:] }
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// responseMessage is the protocol message sent from a control server
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// to a client machine.
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//
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// 1b: message type (0x02)
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// 2b: payload length (48)
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// 32b: control ephemeral public key (cleartext)
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// 16b: message tag (authenticates the whole message)
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type responseMessage [51]byte
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func mkResponseMessage() responseMessage {
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var ret responseMessage
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ret[0] = msgTypeResponse
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binary.BigEndian.PutUint16(ret[1:], uint16(len(ret.Payload())))
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return ret
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}
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func (m *responseMessage) Header() []byte { return m[:headerLen] }
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func (m *responseMessage) Payload() []byte { return m[headerLen:] }
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func (m *responseMessage) Type() byte { return m[0] }
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func (m *responseMessage) Length() int { return int(binary.BigEndian.Uint16(m[1:3])) }
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func (m *responseMessage) EphemeralPub() []byte { return m[headerLen : headerLen+32] }
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func (m *responseMessage) Tag() []byte { return m[headerLen+32:] }
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