CNA-GAP-072: SendDataOptions cannot express XNA's combined Chat flags, and chat packets are always sent reliably

CNA snapshot b0e97bb1  ·  Known Issues › Functional gaps  ·  source links pinned to b0e97bb1

XNA's SendDataOptions is a [Flags] enum whose Chat flag combines with Reliable and InOrder (values 5 to 7); CNA's is a plain enum 0 to 4 without bitwise operators, and the packet codec sends Chat, and any other value, reliably.

Identifier

CNA-GAP-072

Category

Functional gap

Subsystem

Networking & gamer services

Status

Open

Verified against

CNA b0e97bb1 (b0e97bb1bb876f9b3edd6f4ff1ef3067908ae8ac)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

Microsoft::Xna::Framework::Net::SendDataOptions and LocalNetworkGamer::SendData(..., SendDataOptions)

Expected behaviour

XNA 4.0 declares SendDataOptions as [Flags] (decompiled Microsoft.Xna.Framework.Net; read, not executed): None 0, Reliable 1, InOrder 2, ReliableInOrder 3 and Chat 4, and documents that Chat "can be combined with either or both of the Reliable and InOrder flags", with ordered chat packets ordered relative to other chat packets only.

Actual behaviour at TARGET

SendDataOptions.hpp declares a plain enum class with values 0 to 4 and no bitwise operators (its comment follows FNA, whose members are sequential), so SendDataOptions::Chat | SendDataOptions::Reliable does not compile and a combined value can only be produced by a cast. NetPacketCodec::SendDataOptionsToEnetFlags (NetPacketCodec.cpp) maps Reliable, ReliableInOrder and Chat, and any value outside the switch, to ENET_PACKET_FLAG_RELIABLE: chat packets are always reliable, and there is no separately ordered chat stream. CNA's own audit records the difference as GS-AUDIT-016 (gamer-services-issues.md).

Source locations

• modules/net/include/Microsoft/Xna/Framework/Net/SendDataOptions.hpp — plain enum class, values 0 to 4, no bitwise operators
• modules/net/src/Internal/NetPacketCodec.cpp — SendDataOptionsToEnetFlags: Chat and unknown values become ENET_PACKET_FLAG_RELIABLE
• audit/gamer-services/gamer-services-issues.md — GS-AUDIT-016: combined Chat send flags

Evidence

Read at b0e97bb1 and compared with the decompiled XNA 4.0 SendDataOptions; nothing was built or executed. CNA's audit classifies GS-AUDIT-016 as needing further qualification and notes that extra reliability alone does not prove a game-breaking failure; this entry records only the narrower contract.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

The net tests cover each individual option; none combines Chat with another flag.

Regression test

Give SendDataOptions XNA's flag semantics and bitwise operators, map the Chat combinations to their own reliability and ordering, and test each of the eight values between two machines.

Blast radius

Ports that combine Chat with Reliable or InOrder, or rely on chat packets being unreliable or ordered only among themselves: delivery is stronger than requested, so nothing is lost, but ordering and bandwidth differ. Games that use the four plain options are unaffected.

Workaround

Send chat with Reliable or ReliableInOrder explicitly, and do not cast combined values.