New handshake, use softcrdt upstream

src/core/version.go

@@ -4,65 +4,107 @@ package core
 // Used in the initial connection setup and key exchange
 // Some of this could arguably go in wire.go instead
 
-import "crypto/ed25519"
+import (
+	"bytes"
+	"crypto/ed25519"
+	"encoding/binary"
+)
 
 // This is the version-specific metadata exchanged at the start of a connection.
 // 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.
 type version_metadata struct {
-	meta [4]byte
-	ver  uint8 // 1 byte in this version
-	// Everything after this point potentially depends on the version number, and is subject to change in future versions
-	minorVer uint8 // 1 byte in this version
-	key      ed25519.PublicKey
+	majorVer  uint16
+	minorVer  uint16
+	publicKey ed25519.PublicKey
+	priority  uint8
 }
 
+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.
 func version_getBaseMetadata() version_metadata {
 	return version_metadata{
-		meta:     [4]byte{'m', 'e', 't', 'a'},
-		ver:      0,
-		minorVer: 4,
+		majorVer: ProtocolVersionMajor,
+		minorVer: ProtocolVersionMinor,
 	}
 }
 
-// Gets the length of the metadata for this version, used to know how many bytes to read from the start of a connection.
-func version_getMetaLength() (mlen int) {
-	mlen += 4                     // meta
-	mlen++                        // ver, as long as it's < 127, which it is in this version
-	mlen++                        // minorVer, as long as it's < 127, which it is in this version
-	mlen += ed25519.PublicKeySize // key
-	return
-}
-
 // Encodes version metadata into its wire format.
 func (m *version_metadata) encode() []byte {
-	bs := make([]byte, 0, version_getMetaLength())
-	bs = append(bs, m.meta[:]...)
-	bs = append(bs, m.ver)
-	bs = append(bs, m.minorVer)
-	bs = append(bs, m.key[:]...)
-	if len(bs) != version_getMetaLength() {
-		panic("Inconsistent metadata length")
-	}
+	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)
+
 	return bs
 }
 
 // Decodes version metadata from its wire format into the struct.
 func (m *version_metadata) decode(bs []byte) bool {
-	if len(bs) != version_getMetaLength() {
+	meta := [4]byte{'m', 'e', 't', 'a'}
+	if !bytes.Equal(bs[:4], meta[:]) {
 		return false
 	}
-	offset := 0
-	offset += copy(m.meta[:], bs[offset:])
-	m.ver, offset = bs[offset], offset+1
-	m.minorVer, offset = bs[offset], offset+1
-	m.key = append([]byte(nil), bs[offset:]...)
+	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:]
+	}
 	return true
 }
 
 // Checks that the "meta" bytes and the version numbers are the expected values.
 func (m *version_metadata) check() bool {
-	base := version_getBaseMetadata()
-	return base.meta == m.meta && base.ver == m.ver && base.minorVer == m.minorVer
+	switch {
+	case m.majorVer != ProtocolVersionMajor:
+		return false
+	case m.minorVer != ProtocolVersionMinor:
+		return false
+	case len(m.publicKey) != ed25519.PublicKeySize:
+		return false
+	default:
+		return true
+	}
 }