Fixed issue causing frequent disconnects (found by szisti)

When sending or requesting more than 1000 online accounts, peers would be disconnected with an EOF or connection reset error due to an intentional null response. This response has been removed and it will instead now only send the first 1000 accounts, which prevents the disconnections from occurring.

In theory, these accounts should be in a different order on each node, so the 1000 limit should still result in a fairly even propagation of accounts. However, we may want to consider increasing this limit, to maximise the propagation speed.

Thanks to szisti for tracking this one down.

src/main/java/org/qortal/network/message/GetOnlineAccountsMessage.java

@@ -6,6 +6,7 @@
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.qortal.data.network.OnlineAccountData;
 import org.qortal.transform.Transformer;
@@ -25,7 +26,7 @@ public GetOnlineAccountsMessage(List<OnlineAccountData> onlineAccounts) {
 	private GetOnlineAccountsMessage(int id, List<OnlineAccountData> onlineAccounts) {
 		super(id, MessageType.GET_ONLINE_ACCOUNTS);
 
-		this.onlineAccounts = onlineAccounts;
+		this.onlineAccounts = onlineAccounts.stream().limit(MAX_ACCOUNT_COUNT).collect(Collectors.toList());
 	}
 
 	public List<OnlineAccountData> getOnlineAccounts() {
@@ -35,12 +36,9 @@ public List<OnlineAccountData> getOnlineAccounts() {
 	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
 		final int accountCount = bytes.getInt();
 
-		if (accountCount > MAX_ACCOUNT_COUNT)
-			return null;
-
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
 
-		for (int i = 0; i < accountCount; ++i) {
+		for (int i = 0; i < Math.min(MAX_ACCOUNT_COUNT, accountCount); ++i) {
 			long timestamp = bytes.getLong();
 
 			byte[] publicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];

src/main/java/org/qortal/network/message/OnlineAccountsMessage.java

@@ -6,6 +6,7 @@
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.qortal.data.network.OnlineAccountData;
 import org.qortal.transform.Transformer;
@@ -25,7 +26,7 @@ public OnlineAccountsMessage(List<OnlineAccountData> onlineAccounts) {
 	private OnlineAccountsMessage(int id, List<OnlineAccountData> onlineAccounts) {
 		super(id, MessageType.ONLINE_ACCOUNTS);
 
-		this.onlineAccounts = onlineAccounts;
+		this.onlineAccounts = onlineAccounts.stream().limit(MAX_ACCOUNT_COUNT).collect(Collectors.toList());
 	}
 
 	public List<OnlineAccountData> getOnlineAccounts() {
@@ -35,12 +36,9 @@ public List<OnlineAccountData> getOnlineAccounts() {
 	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
 		final int accountCount = bytes.getInt();
 
-		if (accountCount > MAX_ACCOUNT_COUNT)
-			return null;
-
 		List<OnlineAccountData> onlineAccounts = new ArrayList<>(accountCount);
 
-		for (int i = 0; i < accountCount; ++i) {
+		for (int i = 0; i < Math.min(MAX_ACCOUNT_COUNT, accountCount); ++i) {
 			long timestamp = bytes.getLong();
 
 			byte[] signature = new byte[Transformer.SIGNATURE_LENGTH];