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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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20
Assets/Mirror/Runtime/NetworkConnection.cs
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@ -224,6 +224,20 @@ public bool InvokeHandler<T>(T msg) where T : IMessageBase
// -> can be tested easily with a 1000ms send delay and then logging amount received in while loops here
// and in NetworkServer/Client Update. HandleBytes already takes exactly one.
public virtual void TransportReceive(byte[] buffer)
{
// 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
{
// unpack message
NetworkReader reader = new NetworkReader(buffer);
@ -242,6 +256,12 @@ public virtual void TransportReceive(byte[] buffer)
}
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);
}
}
public virtual bool TransportSend(int channelId, byte[] bytes, out byte error)
{