Squash a whole load of races (and mutex half the world)

src/yggdrasil/conn.go

@@ -3,6 +3,7 @@ package yggdrasil
 import (
 	"encoding/hex"
 	"errors"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -15,6 +16,7 @@ type Conn struct {
 	nodeID        *crypto.NodeID
 	nodeMask      *crypto.NodeID
 	session       *sessionInfo
+	sessionMutex  *sync.RWMutex
 	readDeadline  time.Time
 	writeDeadline time.Time
 	expired       bool
@@ -28,7 +30,9 @@ func (c *Conn) startSearch() {
 			return
 		}
 		if sinfo != nil {
+			c.sessionMutex.Lock()
 			c.session = sinfo
+			c.sessionMutex.Unlock()
 		}
 	}
 	doSearch := func() {
@@ -61,15 +65,20 @@ func (c *Conn) startSearch() {
 }
 
 func (c *Conn) Read(b []byte) (int, error) {
+	c.sessionMutex.RLock()
+	defer c.sessionMutex.RUnlock()
 	if c.expired {
 		return 0, errors.New("session is closed")
 	}
 	if c.session == nil {
 		return 0, errors.New("searching for remote side")
 	}
+	c.session.initMutex.RLock()
 	if !c.session.init {
+		c.session.initMutex.RUnlock()
 		return 0, errors.New("waiting for remote side to accept")
 	}
+	c.session.initMutex.RUnlock()
 	select {
 	case p, ok := <-c.session.recv:
 		if !ok {
@@ -93,7 +102,9 @@ func (c *Conn) Read(b []byte) (int, error) {
 				b = b[:len(bs)]
 			}
 			c.session.updateNonce(&p.Nonce)
+			c.session.timeMutex.Lock()
 			c.session.time = time.Now()
+			c.session.timeMutex.Unlock()
 			return nil
 		}()
 		if err != nil {
@@ -108,6 +119,8 @@ func (c *Conn) Read(b []byte) (int, error) {
 }
 
 func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
+	c.sessionMutex.RLock()
+	defer c.sessionMutex.RUnlock()
 	if c.expired {
 		return 0, errors.New("session is closed")
 	}
@@ -118,12 +131,16 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 		return 0, errors.New("searching for remote side")
 	}
 	defer util.PutBytes(b)
+	c.session.initMutex.RLock()
 	if !c.session.init {
-		// To prevent using empty session keys
+		c.session.initMutex.RUnlock()
 		return 0, errors.New("waiting for remote side to accept")
 	}
+	c.session.initMutex.RUnlock()
 	// code isn't multithreaded so appending to this is safe
+	c.session.coordsMutex.RLock()
 	coords := c.session.coords
+	c.session.coordsMutex.RUnlock()
 	// Prepare the payload
 	c.session.myNonceMutex.Lock()
 	payload, nonce := crypto.BoxSeal(&c.session.sharedSesKey, b, &c.session.myNonce)