From 042a3400fe08050ae0e30b8e453ae2f59bb5c50d Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Wed, 12 Dec 2018 22:40:49 +0000
Subject: [PATCH] Wrap the metadata with a mutex to guarantee thread safety
 across core/router/sessions

---
 src/yggdrasil/core.go    | 15 ++++++++++-----
 src/yggdrasil/router.go  |  2 ++
 src/yggdrasil/session.go | 30 +++++++++++++++++++++++-------
 src/yggdrasil/wire.go    |  7 +++++--
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/src/yggdrasil/core.go b/src/yggdrasil/core.go
index 5a9267c..72a11d7 100644
--- a/src/yggdrasil/core.go
+++ b/src/yggdrasil/core.go
@@ -80,11 +80,6 @@ func GetBuildVersion() string {
 	return buildVersion
 }
 
-// Gets the friendly name of this node, as specified in the NodeConfig.
-func (c *Core) GetMeta() metadata {
-	return c.sessions.myMetadata
-}
-
 // Starts up Yggdrasil using the provided NodeConfig, and outputs debug logging
 // through the provided log.Logger. The started stack will include TCP and UDP
 // sockets, a multicast discovery socket, an admin socket, router, switch and
@@ -245,6 +240,16 @@ func (c *Core) GetSubnet() *net.IPNet {
 	return &net.IPNet{IP: subnet, Mask: net.CIDRMask(64, 128)}
 }
 
+// Gets the node metadata.
+func (c *Core) GetMetadata() metadata {
+	return c.sessions.getMetadata()
+}
+
+// Sets the node metadata.
+func (c *Core) SetMetadata(meta metadata) {
+	c.sessions.setMetadata(meta)
+}
+
 // Sets the output logger of the Yggdrasil node after startup. This may be
 // useful if you want to redirect the output later.
 func (c *Core) SetLogger(log *log.Logger) {
diff --git a/src/yggdrasil/router.go b/src/yggdrasil/router.go
index a40563b..8ac59d8 100644
--- a/src/yggdrasil/router.go
+++ b/src/yggdrasil/router.go
@@ -58,7 +58,9 @@ func (r *router) init(core *Core) {
 	r.addr = *address_addrForNodeID(&r.core.dht.nodeID)
 	r.subnet = *address_subnetForNodeID(&r.core.dht.nodeID)
 	in := make(chan []byte, 32) // TODO something better than this...
+	r.core.sessions.myMetadataMutex.RLock()
 	p := r.core.peers.newPeer(&r.core.boxPub, &r.core.sigPub, &boxSharedKey{}, "(self)", r.core.sessions.myMetadata)
+	r.core.sessions.myMetadataMutex.RUnlock()
 	p.out = func(packet []byte) {
 		// This is to make very sure it never blocks
 		select {
diff --git a/src/yggdrasil/session.go b/src/yggdrasil/session.go
index 690f603..a7bed8a 100644
--- a/src/yggdrasil/session.go
+++ b/src/yggdrasil/session.go
@@ -7,6 +7,7 @@ package yggdrasil
 import (
 	"bytes"
 	"encoding/hex"
+	"sync"
 	"time"
 )
 
@@ -128,7 +129,8 @@ type sessions struct {
 	sessionFirewallWhitelist            []string
 	sessionFirewallBlacklist            []string
 	// Metadata for this node
-	myMetadata metadata
+	myMetadata      metadata
+	myMetadataMutex sync.RWMutex
 }
 
 // Initializes the session struct.
@@ -143,8 +145,17 @@ func (ss *sessions) init(core *Core) {
 	ss.lastCleanup = time.Now()
 }
 
-// Enable or disable the session firewall
+// Get the metadata
+func (ss *sessions) getMetadata() metadata {
+	ss.myMetadataMutex.RLock()
+	defer ss.myMetadataMutex.RUnlock()
+	return ss.myMetadata
+}
+
+// Set the metadata
 func (ss *sessions) setMetadata(meta metadata) {
+	ss.myMetadataMutex.Lock()
+	defer ss.myMetadataMutex.Unlock()
 	ss.myMetadata = meta
 }
 
@@ -485,18 +496,23 @@ func (ss *sessions) handlePing(ping *sessionPing) {
 		bs, sinfo.packet = sinfo.packet, nil
 		ss.core.router.sendPacket(bs)
 	}
-	if time.Since(sinfo.metaResTime).Minutes() > 15 {
-		if time.Since(sinfo.metaReqTime).Minutes() > 1 {
-			ss.sendMeta(sinfo, false)
-		}
-	}
+	// This requests metadata from the remote side fairly quickly after
+	// establishing the session, and if other time constraints apply (no more
+	// often than 15 minutes since receiving the last metadata)
+	//if time.Since(sinfo.metaResTime).Minutes() > 15 {
+	//	if time.Since(sinfo.metaReqTime).Minutes() > 1 {
+	//		ss.sendMeta(sinfo, false)
+	//	}
+	//}
 }
 
 func (ss *sessions) sendMeta(sinfo *sessionInfo, isResponse bool) {
+	ss.myMetadataMutex.RLock()
 	meta := sessionMeta{
 		IsResponse: isResponse,
 		Metadata:   ss.myMetadata,
 	}
+	ss.myMetadataMutex.RUnlock()
 	bs := meta.encode()
 	shared := ss.getSharedKey(&ss.core.boxPriv, &sinfo.theirPermPub)
 	payload, nonce := boxSeal(shared, bs, nil)
diff --git a/src/yggdrasil/wire.go b/src/yggdrasil/wire.go
index 7f394d7..2d87a37 100644
--- a/src/yggdrasil/wire.go
+++ b/src/yggdrasil/wire.go
@@ -355,7 +355,7 @@ func (p *sessionPing) decode(bs []byte) bool {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// Encodes a sessionPing into its wire format.
+// Encodes a sessionMeta into its wire format.
 func (p *sessionMeta) encode() []byte {
 	var pTypeVal uint64
 	if p.IsResponse {
@@ -370,7 +370,7 @@ func (p *sessionMeta) encode() []byte {
 	return bs
 }
 
-// Decodes an encoded sessionPing into the struct, returning true if successful.
+// Decodes an encoded sessionMeta into the struct, returning true if successful.
 func (p *sessionMeta) decode(bs []byte) bool {
 	var pType uint64
 	switch {
@@ -380,6 +380,9 @@ func (p *sessionMeta) decode(bs []byte) bool {
 		return false
 	}
 	if p.IsResponse = pType == wire_SessionMetaResponse; p.IsResponse {
+		if len(bs) == 0 {
+			return false
+		}
 		p.Metadata = make(metadata, len(bs))
 		if !wire_chop_slice(p.Metadata[:], &bs) {
 			return false