From 87330995167e7f79b28d9110f6921d6cb003d8b1 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 9 Jun 2018 17:46:19 -0500
Subject: [PATCH] add version metadata to key exchange at the start of
 connections

---
 src/yggdrasil/tcp.go | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/src/yggdrasil/tcp.go b/src/yggdrasil/tcp.go
index c5f7927b..459b51b1 100644
--- a/src/yggdrasil/tcp.go
+++ b/src/yggdrasil/tcp.go
@@ -10,6 +10,10 @@ package yggdrasil
 //  Could be used to DoS (connect, give someone else's keys, spew garbage)
 //  I guess the "peer" part should watch for link packets, disconnect?
 
+// TCP connections start with a metadata exchange.
+//  It involves exchanging version numbers and crypto keys
+//  See version.go for version metadata format
+
 import "net"
 import "time"
 import "errors"
@@ -142,29 +146,43 @@ func (iface *tcpInterface) handler(sock net.Conn, incoming bool) {
 	defer sock.Close()
 	// Get our keys
 	myLinkPub, myLinkPriv := newBoxKeys() // ephemeral link keys
-	keys := []byte{}
-	keys = append(keys, tcp_key[:]...)
-	keys = append(keys, iface.core.boxPub[:]...)
-	keys = append(keys, iface.core.sigPub[:]...)
-	keys = append(keys, myLinkPub[:]...)
-	_, err := sock.Write(keys)
+	meta := version_getBaseMetadata()
+	meta.box = iface.core.boxPub
+	meta.sig = iface.core.sigPub
+	meta.link = *myLinkPub
+	metaBytes := meta.encode()
+	_, err := sock.Write(metaBytes)
 	if err != nil {
 		return
 	}
 	timeout := time.Now().Add(6 * time.Second)
 	sock.SetReadDeadline(timeout)
-	n, err := sock.Read(keys)
+	n, err := sock.Read(metaBytes)
 	if err != nil {
 		return
 	}
-	if n < len(keys) { /*panic("Partial key packet?") ;*/
+	if n != version_getMetaLength() {
 		return
 	}
-	info := tcpInfo{} // used as a map key, so don't include ephemeral link eys
-	var theirLinkPub boxPubKey
-	if !tcp_chop_keys(&info.box, &info.sig, &theirLinkPub, &keys) { /*panic("Invalid key packet?") ;*/
+	meta = version_metadata{} // Reset to zero value
+	if !meta.decode(metaBytes) {
 		return
 	}
+	if !meta.check() {
+		base := version_getBaseMetadata()
+		if meta.meta == base.meta {
+			if meta.ver > base.ver {
+				iface.core.log.Println("Failed to connect to node:", sock.RemoteAddr().String(), "version:", meta.ver)
+			} else if meta.ver == base.ver && meta.minorVer > base.minorVer {
+				iface.core.log.Println("Failed to connect to node:", sock.RemoteAddr().String(), "version:", fmt.Sprintf("%d.%d", meta.ver, meta.minorVer))
+			}
+		}
+		return
+	}
+	info := tcpInfo{ // used as a map key, so don't include ephemeral link key
+		box: meta.box,
+		sig: meta.sig,
+	}
 	// Quit the parent call if this is a connection to ourself
 	equiv := func(k1, k2 []byte) bool {
 		for idx := range k1 {
@@ -210,7 +228,7 @@ func (iface *tcpInterface) handler(sock net.Conn, incoming bool) {
 	}()
 	// Note that multiple connections to the same node are allowed
 	//  E.g. over different interfaces
-	p := iface.core.peers.newPeer(&info.box, &info.sig, getSharedKey(myLinkPriv, &theirLinkPub))
+	p := iface.core.peers.newPeer(&info.box, &info.sig, getSharedKey(myLinkPriv, &meta.link))
 	p.linkOut = make(chan []byte, 1)
 	in := func(bs []byte) {
 		p.handlePacket(bs)