control/noise: review fixups
Signed-off-by: David Anderson <danderson@tailscale.com>
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David Anderson
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Dave Anderson
Dave Anderson
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cf90392174
+72
-40
@@ -6,32 +6,68 @@ package noise
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import "encoding/binary"
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const (
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msgTypeInitiation = 1
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msgTypeResponse = 2
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msgTypeError = 3
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msgTypeRecord = 4
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)
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// headerLen is the size of the cleartext message header that gets
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// prepended to Noise messages.
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// The transport protocol is mostly Noise messages encapsulated in a
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// small header describing the payload's type and length. The one
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// place we deviate from pure Noise+header is that we also support
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// sending an unauthenticated plaintext error as payload, to provide
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// an explanation for a connection error that happens before the
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// handshake completes.
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//
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// All frames in our protocol have a 5-byte header:
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//
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// +------+------+------+------+------+
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// | version | type | length |
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// +------+------+------+------+------+
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//
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// 2b: protocol version
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// 1b: message type
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// 2b: payload length (not including this header)
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// 2b: payload length (not including the header)
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//
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// Multibyte values are all big-endian on the wire, as is traditional
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// for network protocols.
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//
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// The protocol version is 2 bytes in order to encourage frequent
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// revving of the protocol as needed, without fear of running out of
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// version numbers. At minimum, the version number must change
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// whenever any particulars of the Noise handshake change
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// (e.g. switching from Noise IK to Noise IKpsk1 or Noise XX), and
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// when security-critical aspects of the "uppper" protocol within the
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// Noise frames change (e.g. how further authentication data is bound
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// to the underlying Noise session).
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// headerLen is the size of the header that gets prepended to Noise
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// messages.
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const headerLen = 5
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func setHeader(bs []byte, version int, msgType byte, length int) {
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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 a Noise transport message (i.e. "user data").
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msgTypeRecord = 4
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)
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func setHeader(bs []byte, version uint16, msgType byte, length int) {
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binary.LittleEndian.PutUint16(bs[:2], uint16(version))
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bs[2] = msgType
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binary.LittleEndian.PutUint16(bs[3:5], uint16(length))
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}
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func hdrVersion(bs []byte) int { return int(binary.LittleEndian.Uint16(bs[:2])) }
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func hdrType(bs []byte) byte { return bs[2] }
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func hdrLen(bs []byte) int { return int(binary.LittleEndian.Uint16(bs[3:5])) }
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func hdrVersion(bs []byte) uint16 { return binary.LittleEndian.Uint16(bs[:2]) }
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func hdrType(bs []byte) byte { return bs[2] }
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func hdrLen(bs []byte) int { return int(binary.LittleEndian.Uint16(bs[3:5])) }
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// initiationMessage is the Noise protocol message sent from a client
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// machine to a control server.
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// machine to a control server. Aside from the message header, the
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// values are as specified in the Noise specification for the IK
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// handshake pattern.
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//
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// 5b: header (see headerLen for fields)
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// 32b: client ephemeral public key (cleartext)
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@@ -41,47 +77,43 @@ type initiationMessage [101]byte
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func mkInitiationMessage() initiationMessage {
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var ret initiationMessage
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binary.LittleEndian.PutUint16(ret[:2], protocolVersion)
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ret[2] = msgTypeInitiation
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binary.LittleEndian.PutUint16(ret[3:5], 96)
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setHeader(ret[:], protocolVersion, msgTypeInitiation, len(ret.Payload()))
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return ret
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}
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func (m *initiationMessage) Header() []byte { return m[:5] }
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func (m *initiationMessage) Payload() []byte { return m[5:] }
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func (m *initiationMessage) Header() []byte { return m[:headerLen] }
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func (m *initiationMessage) Payload() []byte { return m[headerLen:] }
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func (m *initiationMessage) Version() int { return hdrVersion(m.Header()) }
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func (m *initiationMessage) Type() byte { return hdrType(m.Header()) }
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func (m *initiationMessage) Length() int { return hdrLen(m.Header()) }
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func (m *initiationMessage) Version() uint16 { return hdrVersion(m.Header()) }
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func (m *initiationMessage) Type() byte { return hdrType(m.Header()) }
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func (m *initiationMessage) Length() int { return hdrLen(m.Header()) }
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func (m *initiationMessage) EphemeralPub() []byte { return m[5:37] }
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func (m *initiationMessage) MachinePub() []byte { return m[37:85] }
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func (m *initiationMessage) Tag() []byte { return m[85:] }
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func (m *initiationMessage) EphemeralPub() []byte { return m[headerLen : headerLen+32] }
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func (m *initiationMessage) MachinePub() []byte { return m[headerLen+32 : headerLen+32+48] }
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func (m *initiationMessage) Tag() []byte { return m[headerLen+32+48:] }
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// responseMessage is the Noise protocol message sent from a control
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// server to a client machine.
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// server to a client machine. Aside from the message header, the
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// values are as specified in the Noise specification for the IK
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// handshake pattern.
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//
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// 2b: little-endian protocol version
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// 1b: message type
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// 2b: little-endian size of message (not including this header)
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// 5b: header (see headerLen for fields)
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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 [53]byte
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func mkResponseMessage() responseMessage {
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var ret responseMessage
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binary.LittleEndian.PutUint16(ret[:2], protocolVersion)
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ret[2] = msgTypeResponse
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binary.LittleEndian.PutUint16(ret[3:5], 48)
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setHeader(ret[:], protocolVersion, msgTypeResponse, len(ret.Payload()))
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return ret
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}
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func (m *responseMessage) Header() []byte { return m[:5] }
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func (m *responseMessage) Payload() []byte { return m[5:] }
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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) Version() int { return hdrVersion(m.Header()) }
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func (m *responseMessage) Type() byte { return hdrType(m.Header()) }
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func (m *responseMessage) Length() int { return hdrLen(m.Header()) }
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func (m *responseMessage) Version() uint16 { return hdrVersion(m.Header()) }
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func (m *responseMessage) Type() byte { return hdrType(m.Header()) }
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func (m *responseMessage) Length() int { return hdrLen(m.Header()) }
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func (m *responseMessage) EphemeralPub() []byte { return m[5:37] }
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func (m *responseMessage) Tag() []byte { return m[37:] }
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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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