multi: Handle detected data race conditions

All instances of data race are related to accessing
KnownAddress elements, except for peer.go where its
related to closure.

Following are the changes:
- Add KnownAddress.mtx (sync.Mutex) and used same to
 sync access points
- For peer.go, pass local copy to the closure

addrmgr/addrmanager.go

@@ -183,7 +183,9 @@ func (a *AddrManager) updateAddress(netAddr, srcAddr *wire.NetAddress) {
 			naCopy := *ka.na
 			naCopy.Timestamp = netAddr.Timestamp
 			naCopy.AddService(netAddr.Services)
+			ka.mtx.Lock()
 			ka.na = &naCopy
+			ka.mtx.Unlock()
 		}
 
 		// If already in tried, we have nothing to do here.
@@ -823,9 +825,12 @@ func (a *AddrManager) Attempt(addr *wire.NetAddress) {
 	if ka == nil {
 		return
 	}
+
 	// set last tried time to now
+	ka.mtx.Lock()
 	ka.attempts++
 	ka.lastattempt = time.Now()
+	ka.mtx.Unlock()
 }
 
 // Connected Marks the given address as currently connected and working at the

addrmgr/knownaddress.go

@@ -6,6 +6,7 @@
 package addrmgr
 
 import (
+	"sync"
 	"time"
 
 	"github.com/decred/dcrd/wire"
@@ -14,6 +15,7 @@ import (
 // KnownAddress tracks information about a known network address that is used
 // to determine how viable an address is.
 type KnownAddress struct {
+	mtx         sync.Mutex
 	na          *wire.NetAddress
 	srcAddr     *wire.NetAddress
 	attempts    int
@@ -26,18 +28,24 @@ type KnownAddress struct {
 // NetAddress returns the underlying wire.NetAddress associated with the
 // known address.
 func (ka *KnownAddress) NetAddress() *wire.NetAddress {
+	ka.mtx.Lock()
+	defer ka.mtx.Unlock()
 	return ka.na
 }
 
 // LastAttempt returns the last time the known address was attempted.
 func (ka *KnownAddress) LastAttempt() time.Time {
+	ka.mtx.Lock()
+	defer ka.mtx.Unlock()
 	return ka.lastattempt
 }
 
 // chance returns the selection probability for a known address.  The priority
 // depends upon how recently the address has been seen, how recently it was last
 // attempted and how often attempts to connect to it have failed.
 func (ka *KnownAddress) chance() float64 {
+	ka.mtx.Lock()
+	defer ka.mtx.Unlock()
 	now := time.Now()
 	lastSeen := now.Sub(ka.na.Timestamp)
 	lastAttempt := now.Sub(ka.lastattempt)
@@ -73,6 +81,8 @@ func (ka *KnownAddress) chance() float64 {
 // All addresses that meet these criteria are assumed to be worthless and not
 // worth keeping hold of.
 func (ka *KnownAddress) isBad() bool {
+	ka.mtx.Lock()
+	defer ka.mtx.Unlock()
 	if ka.lastattempt.After(time.Now().Add(-1 * time.Minute)) {
 		return false
 	}

peer/peer.go

@@ -1861,12 +1861,12 @@ func (p *Peer) AssociateConnection(conn net.Conn) {
 		p.na = na
 	}
 
-	go func() {
-		if err := p.start(); err != nil {
-			log.Debugf("Cannot start peer %v: %v", p, err)
-			p.Disconnect()
+	go func(peer *Peer) {
+		if err := peer.start(); err != nil {
+			log.Debugf("Cannot start peer %v: %v", peer, err)
+			peer.Disconnect()
 		}
-	}()
+	}(p)
 }
 
 // Connected returns whether or not the peer is currently connected.