network: fix race in TestHandleGetMPTData

Init server config before server start. Fixes the following data race:

```
WARNING: DATA RACE
Write at 0x00c00032ef20 by goroutine 26:
  github.com/nspcc-dev/neo-go/pkg/network.TestHandleGetMPTData.func2()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:755 +0x10a
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1193 +0x202

Previous read at 0x00c00032ef20 by goroutine 24:
  github.com/nspcc-dev/neo-go/internal/fakechain.(*FakeChain).GetConfig()
      /go/src/github.com/nspcc-dev/neo-go/internal/fakechain/fakechain.go:167 +0x6f
  github.com/nspcc-dev/neo-go/pkg/network.(*Server).initStaleMemPools()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server.go:1433 +0x89
  github.com/nspcc-dev/neo-go/pkg/network.(*Server).Start()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server.go:284 +0x288
  github.com/nspcc-dev/neo-go/pkg/network.startWithChannel.func1()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:91 +0x44

Goroutine 26 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:1238 +0x5d7
  github.com/nspcc-dev/neo-go/pkg/network.TestHandleGetMPTData()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:752 +0x8c
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1193 +0x202

Goroutine 24 (running) created at:
  github.com/nspcc-dev/neo-go/pkg/network.startWithChannel()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:90 +0x78
  github.com/nspcc-dev/neo-go/pkg/network.startTestServer()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:384 +0xbd
  github.com/nspcc-dev/neo-go/pkg/network.TestHandleGetMPTData.func2()
      /go/src/github.com/nspcc-dev/neo-go/pkg/network/server_test.go:753 +0x55
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1193 +0x202
```

internal/fakechain/fakechain.go

@@ -55,6 +55,15 @@ type FakeStateSync struct {
 
 // NewFakeChain returns new FakeChain structure.
 func NewFakeChain() *FakeChain {
+	return NewFakeChainWithCustomCfg(nil)
+}
+
+// NewFakeChainWithCustomCfg returns new FakeChain structure with specified protocol configuration.
+func NewFakeChainWithCustomCfg(protocolCfg func(c *config.ProtocolConfiguration)) *FakeChain {
+	cfg := config.ProtocolConfiguration{Magic: netmode.UnitTestNet, P2PNotaryRequestPayloadPoolSize: 10}
+	if protocolCfg != nil {
+		protocolCfg(&cfg)
+	}
 	return &FakeChain{
 		Pool:                  mempool.New(10, 0, false),
 		PoolTxF:               func(*transaction.Transaction) error { return nil },
@@ -62,7 +71,7 @@ func NewFakeChain() *FakeChain {
 		blocks:                make(map[util.Uint256]*block.Block),
 		hdrHashes:             make(map[uint32]util.Uint256),
 		txs:                   make(map[util.Uint256]*transaction.Transaction),
-		ProtocolConfiguration: config.ProtocolConfiguration{Magic: netmode.UnitTestNet, P2PNotaryRequestPayloadPoolSize: 10},
+		ProtocolConfiguration: cfg,
 	}
 }
 

pkg/network/helper_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/nspcc-dev/neo-go/internal/fakechain"
+	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/network/capability"
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
@@ -187,7 +188,11 @@ func (p *localPeer) CanProcessAddr() bool {
 }
 
 func newTestServer(t *testing.T, serverConfig ServerConfig) *Server {
-	s, err := newServerFromConstructors(serverConfig, fakechain.NewFakeChain(), zaptest.NewLogger(t),
+	return newTestServerWithCustomCfg(t, serverConfig, nil)
+}
+
+func newTestServerWithCustomCfg(t *testing.T, serverConfig ServerConfig, protocolCfg func(*config.ProtocolConfiguration)) *Server {
+	s, err := newServerFromConstructors(serverConfig, fakechain.NewFakeChainWithCustomCfg(protocolCfg), zaptest.NewLogger(t),
 		newFakeTransp, newFakeConsensus, newTestDiscovery)
 	require.NoError(t, err)
 	t.Cleanup(s.discovery.Close)

pkg/network/server_test.go

@@ -379,8 +379,14 @@ func (s *Server) testHandleMessage(t *testing.T, p Peer, cmd CommandType, pl pay
 	return s
 }
 
-func startTestServer(t *testing.T) *Server {
+func startTestServer(t *testing.T, protocolCfg ...func(*config.ProtocolConfiguration)) *Server {
-	s := newTestServer(t, ServerConfig{Port: 0, UserAgent: "/test/"})
+	var s *Server
+	srvCfg := ServerConfig{Port: 0, UserAgent: "/test/"}
+	if protocolCfg != nil {
+		s = newTestServerWithCustomCfg(t, srvCfg, protocolCfg[0])
+	} else {
+		s = newTestServer(t, srvCfg)
+	}
 	ch := startWithChannel(s)
 	t.Cleanup(func() {
 		s.Shutdown()
@@ -750,9 +756,10 @@ func TestHandleGetMPTData(t *testing.T) {
 	})
 
 	t.Run("KeepOnlyLatestState on", func(t *testing.T) {
-		s := startTestServer(t)
+		s := startTestServer(t, func(c *config.ProtocolConfiguration) {
-		s.chain.(*fakechain.FakeChain).P2PStateExchangeExtensions = true
+			c.P2PStateExchangeExtensions = true
-		s.chain.(*fakechain.FakeChain).KeepOnlyLatestState = true
+			c.KeepOnlyLatestState = true
+		})
 		p := newLocalPeer(t, s)
 		p.handshaked = true
 		msg := NewMessage(CMDGetMPTData, &payload.MPTInventory{
@@ -762,8 +769,9 @@ func TestHandleGetMPTData(t *testing.T) {
 	})
 
 	t.Run("good", func(t *testing.T) {
-		s := startTestServer(t)
+		s := startTestServer(t, func(c *config.ProtocolConfiguration) {
-		s.chain.(*fakechain.FakeChain).P2PStateExchangeExtensions = true
+			c.P2PStateExchangeExtensions = true
+		})
 		var recvResponse atomic.Bool
 		r1 := random.Uint256()
 		r2 := random.Uint256()