move router.recvPacket calls into the main router goroutine, to make the ckr checks threadsafe

src/yggdrasil/router.go

@@ -38,6 +38,7 @@ type router struct {
 	subnet    subnet
 	in        <-chan []byte          // packets we received from the network, link to peer's "out"
 	out       func([]byte)           // packets we're sending to the network, link to peer's "in"
+	toRecv    chan router_recvPacket // packets to handle via recvPacket()
 	recv      chan<- []byte          // place where the tun pulls received packets from
 	send      <-chan []byte          // place where the tun puts outgoing packets
 	reset     chan struct{}          // signal that coords changed (re-init sessions/dht)
@@ -45,6 +46,12 @@ type router struct {
 	cryptokey cryptokey
 }
 
+// Packet and session info, used to check that the packet matches a valid IP range or CKR prefix before sending to the tun.
+type router_recvPacket struct {
+	bs    []byte
+	sinfo *sessionInfo
+}
+
 // Initializes the router struct, which includes setting up channels to/from the tun/tap.
 func (r *router) init(core *Core) {
 	r.core = core
@@ -63,6 +70,7 @@ func (r *router) init(core *Core) {
 	}
 	r.in = in
 	r.out = func(packet []byte) { p.handlePacket(packet) } // The caller is responsible for go-ing if it needs to not block
+	r.toRecv = make(chan router_recvPacket, 32)
 	recv := make(chan []byte, 32)
 	send := make(chan []byte, 32)
 	r.recv = recv
@@ -70,7 +78,7 @@ func (r *router) init(core *Core) {
 	r.core.tun.recv = recv
 	r.core.tun.send = send
 	r.reset = make(chan struct{}, 1)
-	r.admin = make(chan func())
+	r.admin = make(chan func(), 32)
 	r.cryptokey.init(r.core)
 	// go r.mainLoop()
 }
@@ -91,6 +99,8 @@ func (r *router) mainLoop() {
 	defer ticker.Stop()
 	for {
 		select {
+		case rp := <-r.toRecv:
+			r.recvPacket(rp.bs, rp.sinfo)
 		case p := <-r.in:
 			r.handleIn(p)
 		case p := <-r.send:

src/yggdrasil/session.go

@@ -589,5 +589,5 @@ func (sinfo *sessionInfo) doRecv(p *wire_trafficPacket) {
 	sinfo.updateNonce(&p.Nonce)
 	sinfo.time = time.Now()
 	sinfo.bytesRecvd += uint64(len(bs))
-	sinfo.core.router.recvPacket(bs, sinfo)
+	sinfo.core.router.toRecv <- router_recvPacket{bs, sinfo}
 }