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Transport.TransportReceive catches exceptions and disconnects the connection after invalid data was received. (#737)

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This commit is contained in:
vis2k 2019-04-06 00:17:03 +02:00
parent 7d2c5e5b0e
commit cc16df72cc
1 changed files with 31 additions and 11 deletions
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42
Assets/Mirror/Runtime/NetworkConnection.cs
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@ -225,22 +225,42 @@ public bool InvokeHandler<T>(T msg) where T : IMessageBase
// and in NetworkServer/Client Update. HandleBytes already takes exactly one.
public virtual void TransportReceive(byte[] buffer)
{
// unpack message
NetworkReader reader = new NetworkReader(buffer);
if (MessagePacker.UnpackMessage(reader, out int msgType))
// protect against DOS attacks if attackers try to send invalid
// data packets to crash the server/client. there are a thousand
// ways to cause an exception in data handling:
// - invalid headers
// - invalid message ids
// - invalid data causing exceptions
// - negative ReadBytesAndSize prefixes
// - invalid utf8 strings
// - etc.
//
// let's catch them all and then disconnect that connection to avoid
// further attacks.
try
{
if (logNetworkMessages)
// unpack message
NetworkReader reader = new NetworkReader(buffer);
if (MessagePacker.UnpackMessage(reader, out int msgType))
{
Debug.Log("ConnectionRecv con:" + connectionId + " msgType:" + msgType + " content:" + BitConverter.ToString(buffer));
}
if (logNetworkMessages)
{
Debug.Log("ConnectionRecv con:" + connectionId + " msgType:" + msgType + " content:" + BitConverter.ToString(buffer));
}
// try to invoke the handler for that message
if (InvokeHandler(msgType, reader))
{
lastMessageTime = Time.time;
// try to invoke the handler for that message
if (InvokeHandler(msgType, reader))
{
lastMessageTime = Time.time;
}
}
else Debug.LogError("HandleBytes UnpackMessage failed for: " + BitConverter.ToString(buffer));
}
catch (Exception exception)
{
Disconnect();
Debug.LogWarning("Closed connection: " + connectionId + ". This can happen if the other side accidentally (or an attacker intentionally) sent invalid data. Reason: " + exception);
}
else Debug.LogError("HandleBytes UnpackMessage failed for: " + BitConverter.ToString(buffer));
}
public virtual bool TransportSend(int channelId, byte[] bytes, out byte error)