From 818eca90dbbcc973852dfd4274fa6cf3a71db00a Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 29 Jun 2019 16:10:02 -0500
Subject: [PATCH] fix nil pointer deref if searches fail, block dial until a
 search exceeds or a timeout passes (todo: replace timer with context)

---
 src/yggdrasil/conn.go    | 14 ++++++++------
 src/yggdrasil/dialer.go  | 12 +++++++++++-
 src/yggdrasil/router.go  |  2 +-
 src/yggdrasil/session.go | 17 +++++++++++++----
 4 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/src/yggdrasil/conn.go b/src/yggdrasil/conn.go
index 0357ccad..53d2551e 100644
--- a/src/yggdrasil/conn.go
+++ b/src/yggdrasil/conn.go
@@ -89,11 +89,13 @@ func (c *Conn) search() error {
 		<-done
 		c.session = sess
 		if c.session == nil && err == nil {
-			panic("search failed but returend no error")
+			panic("search failed but returned no error")
 		}
-		c.nodeID = crypto.GetNodeID(&c.session.theirPermPub)
-		for i := range c.nodeMask {
-			c.nodeMask[i] = 0xFF
+		if c.session != nil {
+			c.nodeID = crypto.GetNodeID(&c.session.theirPermPub)
+			for i := range c.nodeMask {
+				c.nodeMask[i] = 0xFF
+			}
 		}
 		return err
 	} else {
@@ -218,8 +220,6 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 			go func() { c.core.router.admin <- routerWork }()
 		}
 		switch {
-		case !sinfo.init:
-			sinfo.core.sessions.ping(sinfo)
 		case time.Since(sinfo.time) > 6*time.Second:
 			if sinfo.time.Before(sinfo.pingTime) && time.Since(sinfo.pingTime) > 6*time.Second {
 				// TODO double check that the above condition is correct
@@ -227,6 +227,8 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 			} else {
 				sinfo.core.sessions.ping(sinfo)
 			}
+		case sinfo.reset && sinfo.pingTime.Before(sinfo.time):
+			sinfo.core.sessions.ping(sinfo)
 		default: // Don't do anything, to keep traffic throttled
 		}
 	}
diff --git a/src/yggdrasil/dialer.go b/src/yggdrasil/dialer.go
index 1e3e0d6e..6b24cfb4 100644
--- a/src/yggdrasil/dialer.go
+++ b/src/yggdrasil/dialer.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 )
@@ -61,7 +62,16 @@ func (d *Dialer) Dial(network, address string) (*Conn, error) {
 func (d *Dialer) DialByNodeIDandMask(nodeID, nodeMask *crypto.NodeID) (*Conn, error) {
 	conn := newConn(d.core, nodeID, nodeMask, nil)
 	if err := conn.search(); err != nil {
+		conn.Close()
 		return nil, err
 	}
-	return conn, nil
+	t := time.NewTimer(6 * time.Second) // TODO use a context instead
+	defer t.Stop()
+	select {
+	case <-conn.session.init:
+		return conn, nil
+	case <-t.C:
+		conn.Close()
+		return nil, errors.New("session handshake timeout")
+	}
 }
diff --git a/src/yggdrasil/router.go b/src/yggdrasil/router.go
index 2e32fb6b..514d14fa 100644
--- a/src/yggdrasil/router.go
+++ b/src/yggdrasil/router.go
@@ -119,7 +119,7 @@ func (r *router) mainLoop() {
 		case info := <-r.core.dht.peers:
 			r.core.dht.insertPeer(info)
 		case <-r.reset:
-			r.core.sessions.resetInits()
+			r.core.sessions.reset()
 			r.core.dht.reset()
 		case <-ticker.C:
 			{
diff --git a/src/yggdrasil/session.go b/src/yggdrasil/session.go
index dc3f01e8..98a12c7b 100644
--- a/src/yggdrasil/session.go
+++ b/src/yggdrasil/session.go
@@ -39,12 +39,13 @@ type sessionInfo struct {
 	pingTime       time.Time                // time the first ping was sent since the last received packet
 	pingSend       time.Time                // time the last ping was sent
 	coords         []byte                   // coords of destination
-	init           bool                     // Reset if coords change
+	reset          bool                     // reset if coords change
 	tstamp         int64                    // ATOMIC - tstamp from their last session ping, replay attack mitigation
 	bytesSent      uint64                   // Bytes of real traffic sent in this session
 	bytesRecvd     uint64                   // Bytes of real traffic received in this session
 	worker         chan func()              // Channel to send work to the session worker
 	recv           chan *wire_trafficPacket // Received packets go here, picked up by the associated Conn
+	init           chan struct{}            // Closed when the first session pong arrives, used to signal that the session is ready for initial use
 }
 
 func (sinfo *sessionInfo) doWorker(f func()) {
@@ -101,7 +102,14 @@ func (s *sessionInfo) update(p *sessionPing) bool {
 	}
 	s.time = time.Now()
 	s.tstamp = p.Tstamp
-	s.init = true
+	s.reset = false
+	defer func() { recover() }() // Recover if the below panics
+	select {
+	case <-s.init:
+	default:
+		// Unblock anything waiting for the session to initialize
+		close(s.init)
+	}
 	return true
 }
 
@@ -203,6 +211,7 @@ func (ss *sessions) createSession(theirPermKey *crypto.BoxPubKey) *sessionInfo {
 	sinfo.mtuTime = now
 	sinfo.pingTime = now
 	sinfo.pingSend = now
+	sinfo.init = make(chan struct{})
 	higher := false
 	for idx := range ss.core.boxPub {
 		if ss.core.boxPub[idx] > sinfo.theirPermPub[idx] {
@@ -410,10 +419,10 @@ func (sinfo *sessionInfo) updateNonce(theirNonce *crypto.BoxNonce) {
 
 // Resets all sessions to an uninitialized state.
 // Called after coord changes, so attemtps to use a session will trigger a new ping and notify the remote end of the coord change.
-func (ss *sessions) resetInits() {
+func (ss *sessions) reset() {
 	for _, sinfo := range ss.sinfos {
 		sinfo.doWorker(func() {
-			sinfo.init = false
+			sinfo.reset = true
 		})
 	}
 }