From 28db566b37b14224ffbf1505b89d8eab2a0d0f32 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 29 Jun 2019 18:44:24 -0500
Subject: [PATCH 1/3] fix concurrency bug in iface.go

---
 src/tuntap/iface.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tuntap/iface.go b/src/tuntap/iface.go
index f6cfec9c..16a3b65d 100644
--- a/src/tuntap/iface.go
+++ b/src/tuntap/iface.go
@@ -225,11 +225,11 @@ func (tun *TunAdapter) reader() error {
 				panic("Given empty dstNodeID and dstNodeIDMask - this shouldn't happen")
 			}
 			// Dial to the remote node
+			packet := append(util.GetBytes(), bs[:n]...)
 			go func() {
 				// FIXME just spitting out a goroutine to do this is kind of ugly and means we drop packets until the dial finishes
 				tun.mutex.Lock()
 				_, known := tun.dials[*dstNodeID]
-				packet := append(util.GetBytes(), bs[:n]...)
 				tun.dials[*dstNodeID] = append(tun.dials[*dstNodeID], packet)
 				for len(tun.dials[*dstNodeID]) > 32 {
 					util.PutBytes(tun.dials[*dstNodeID][0])

From d39428735df66a39acef3da98c2ca3eac5237a15 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 29 Jun 2019 18:50:21 -0500
Subject: [PATCH 2/3] recover if we try to send to a closed session worker due
 to a race between a Conn.Write call and a Conn.Close call

---
 src/yggdrasil/conn.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/yggdrasil/conn.go b/src/yggdrasil/conn.go
index 38e4df9f..b4f68e18 100644
--- a/src/yggdrasil/conn.go
+++ b/src/yggdrasil/conn.go
@@ -236,6 +236,11 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 	timer := getDeadlineTimer(&c.writeDeadline)
 	defer util.TimerStop(timer)
 	// Hand over to the session worker
+	defer func() {
+		if recover() != nil {
+			err = errors.New("write failed")
+		}
+	}() // In case we're racing with a close
 	select { // Send to worker
 	case sinfo.worker <- workerFunc:
 	case <-timer.C:

From 40553a6a44e88c3df8e164f7b2386d92c3bc93cc Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 29 Jun 2019 18:56:26 -0500
Subject: [PATCH 3/3] make GetSessions use the session workers to avoid races

---
 src/yggdrasil/api.go | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/src/yggdrasil/api.go b/src/yggdrasil/api.go
index 864e7f37..7270bc2e 100644
--- a/src/yggdrasil/api.go
+++ b/src/yggdrasil/api.go
@@ -211,16 +211,31 @@ func (c *Core) GetSessions() []Session {
 	var sessions []Session
 	getSessions := func() {
 		for _, sinfo := range c.sessions.sinfos {
-			// TODO? skipped known but timed out sessions?
-			session := Session{
-				Coords:      append([]byte{}, sinfo.coords...),
-				MTU:         sinfo.getMTU(),
-				BytesSent:   sinfo.bytesSent,
-				BytesRecvd:  sinfo.bytesRecvd,
-				Uptime:      time.Now().Sub(sinfo.timeOpened),
-				WasMTUFixed: sinfo.wasMTUFixed,
+			var session Session
+			workerFunc := func() {
+				session := Session{
+					Coords:      append([]byte{}, sinfo.coords...),
+					MTU:         sinfo.getMTU(),
+					BytesSent:   sinfo.bytesSent,
+					BytesRecvd:  sinfo.bytesRecvd,
+					Uptime:      time.Now().Sub(sinfo.timeOpened),
+					WasMTUFixed: sinfo.wasMTUFixed,
+				}
+				copy(session.PublicKey[:], sinfo.theirPermPub[:])
 			}
-			copy(session.PublicKey[:], sinfo.theirPermPub[:])
+			var skip bool
+			func() {
+				defer func() {
+					if recover() != nil {
+						skip = true
+					}
+				}()
+				sinfo.doWorker(workerFunc)
+			}()
+			if skip {
+				continue
+			}
+			// TODO? skipped known but timed out sessions?
 			sessions = append(sessions, session)
 		}
 	}