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yggdrasil-go/src/core/version.go

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package core
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// This file contains the version metadata struct
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// Used in the initial connection setup and key exchange
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// Some of this could arguably go in wire.go instead
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import (
"bytes"
"crypto/ed25519"
"encoding/binary"
)
// This is the version-specific metadata exchanged at the start of a connection.
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// It must always begin with the 4 bytes "meta" and a wire formatted uint64 major version number.
// The current version also includes a minor version number, and the box/sig/link keys that need to be exchanged to open a connection.
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type version_metadata struct {
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majorVer uint16
minorVer uint16
publicKey ed25519.PublicKey
priority uint8
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}
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const (
ProtocolVersionMajor uint16 = 0
ProtocolVersionMinor uint16 = 5
)
const (
metaVersionMajor uint16 = iota // uint16
metaVersionMinor // uint16
metaPublicKey // [32]byte
metaPriority // uint8
)
// Gets a base metadata with no keys set, but with the correct version numbers.
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func version_getBaseMetadata() version_metadata {
return version_metadata{
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majorVer: ProtocolVersionMajor,
minorVer: ProtocolVersionMinor,
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}
}
// Encodes version metadata into its wire format.
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func (m *version_metadata) encode() []byte {
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bs := make([]byte, 0, 64)
bs = append(bs, 'm', 'e', 't', 'a')
bs = binary.BigEndian.AppendUint16(bs, metaVersionMajor)
bs = binary.BigEndian.AppendUint16(bs, 2)
bs = binary.BigEndian.AppendUint16(bs, m.majorVer)
bs = binary.BigEndian.AppendUint16(bs, metaVersionMinor)
bs = binary.BigEndian.AppendUint16(bs, 2)
bs = binary.BigEndian.AppendUint16(bs, m.minorVer)
bs = binary.BigEndian.AppendUint16(bs, metaPublicKey)
bs = binary.BigEndian.AppendUint16(bs, ed25519.PublicKeySize)
bs = append(bs, m.publicKey[:]...)
bs = binary.BigEndian.AppendUint16(bs, metaPriority)
bs = binary.BigEndian.AppendUint16(bs, 1)
bs = append(bs, m.priority)
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return bs
}
// Decodes version metadata from its wire format into the struct.
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func (m *version_metadata) decode(bs []byte) bool {
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meta := [4]byte{'m', 'e', 't', 'a'}
if !bytes.Equal(bs[:4], meta[:]) {
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return false
}
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for bs = bs[4:]; len(bs) >= 4; {
op := binary.BigEndian.Uint16(bs[:2])
oplen := binary.BigEndian.Uint16(bs[2:4])
if bs = bs[4:]; len(bs) < int(oplen) {
break
}
switch op {
case metaVersionMajor:
m.majorVer = binary.BigEndian.Uint16(bs[:2])
case metaVersionMinor:
m.minorVer = binary.BigEndian.Uint16(bs[:2])
case metaPublicKey:
m.publicKey = make(ed25519.PublicKey, ed25519.PublicKeySize)
copy(m.publicKey, bs[:ed25519.PublicKeySize])
case metaPriority:
m.priority = bs[0]
}
bs = bs[oplen:]
}
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return true
}
// Checks that the "meta" bytes and the version numbers are the expected values.
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func (m *version_metadata) check() bool {
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switch {
case m.majorVer != ProtocolVersionMajor:
return false
case m.minorVer != ProtocolVersionMinor:
return false
case len(m.publicKey) != ed25519.PublicKeySize:
return false
default:
return true
}
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}