server: fix wireToAddrmgrNetAddress data race.

This fixes a data race for the network address passed into
wireToAddrmgrNetAddress.

go.mod

@@ -5,7 +5,7 @@ go 1.16
 require (
 	github.com/davecgh/go-spew v1.1.1
 	github.com/decred/base58 v1.0.3
-	github.com/decred/dcrd/addrmgr/v2 v2.0.0-20210802141345-893802fc06b0
+	github.com/decred/dcrd/addrmgr/v2 v2.0.0-20211005210707-931a579e127b
 	github.com/decred/dcrd/bech32 v1.1.1
 	github.com/decred/dcrd/blockchain/stake/v4 v4.0.0-20210906140327-598bf66f24a6
 	github.com/decred/dcrd/blockchain/standalone/v2 v2.0.0

peer/go.mod

@@ -4,6 +4,7 @@ go 1.11
 
 require (
 	github.com/davecgh/go-spew v1.1.1
+	github.com/decred/dcrd/addrmgr/v2 v2.0.0-20211005210707-931a579e127b
 	github.com/decred/dcrd/chaincfg/chainhash v1.0.2
 	github.com/decred/dcrd/lru v1.1.0
 	github.com/decred/dcrd/txscript/v4 v4.0.0-20210129190127-4ebd135a82f1

peer/go.sum

@@ -6,6 +6,8 @@ github.com/dchest/siphash v1.2.2 h1:9DFz8tQwl9pTVt5iok/9zKyzA1Q6bRGiF3HPiEEVr9I=
 github.com/dchest/siphash v1.2.2/go.mod h1:q+IRvb2gOSrUnYoPqHiyHXS0FOBBOdl6tONBlVnOnt4=
 github.com/decred/base58 v1.0.3 h1:KGZuh8d1WEMIrK0leQRM47W85KqCAdl2N+uagbctdDI=
 github.com/decred/base58 v1.0.3/go.mod h1:pXP9cXCfM2sFLb2viz2FNIdeMWmZDBKG3ZBYbiSM78E=
+github.com/decred/dcrd/addrmgr/v2 v2.0.0-20211005210707-931a579e127b h1:T2pIvkj+0DRUxfw0e9k4XvvNHGELAaertBpTO3Ks0KI=
+github.com/decred/dcrd/addrmgr/v2 v2.0.0-20211005210707-931a579e127b/go.mod h1:pFpkgqaKOORZmZ+GwO719PaXqBvBqt5ATUbMQ3QgYl8=
 github.com/decred/dcrd/chaincfg/chainhash v1.0.2 h1:rt5Vlq/jM3ZawwiacWjPa+smINyLRN07EO0cNBV6DGU=
 github.com/decred/dcrd/chaincfg/chainhash v1.0.2/go.mod h1:BpbrGgrPTr3YJYRN3Bm+D9NuaFd+zGyNeIKgrhCXK60=
 github.com/decred/dcrd/chaincfg/v3 v3.0.0 h1:+TFbu7ZmvBwM+SZz5mrj6cun9ts/6DAL5sqnsaFBHGQ=

peer/peer.go

@@ -579,10 +579,14 @@ func (p *Peer) ID() int32 {
 // This function is safe for concurrent access.
 func (p *Peer) NA() *wire.NetAddress {
 	p.flagsMtx.Lock()
-	na := p.na
+	if p.na == nil {
+		p.flagsMtx.Unlock()
+		return nil
+	}
+	na := *p.na
 	p.flagsMtx.Unlock()
 
-	return na
+	return &na
 }
 
 // Addr returns the peer address.
@@ -1852,7 +1856,7 @@ func (p *Peer) localVersionMsg() (*wire.MsgVersion, error) {
 		}
 	}
 
-	theirNA := p.na
+	theirNA := p.NA()
 
 	// If we are behind a proxy and the connection comes from the proxy then
 	// we return an unroutable address as their address. This is to prevent