Fix silent truncation of UDP datagrams over 1024 bytes#499
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recvfrom() into a 1 KB buffer clips any larger datagram and the tail is lost. A compressed position packet from a client with several moving vehicles exceeds that, so those updates were silently dropped and the remote vehicles stuttered/warped. Size the receive buffer to the UDP maximum instead. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Problem
TNetwork::UDPRcvFromClientreceives into a fixedstd::array<char, 1024>. UDPrecvfrom()truncates any datagram larger than the buffer — the tail is silently lost. A compressed (ABG:) position packet from a client with several moving vehicles can exceed 1 KB, so those updates were silently dropped (the truncated payload fails to decompress/parse), and other players saw those vehicles stutter or warp.Fix
Size the receive buffer to the UDP maximum (65535). One-line change plus a comment; the function already returns only the received byte count, so there is no behavior change for small datagrams.
How this was found
Diagnosed while profiling remote-vehicle drift on a LAN fork of BeamMP (position updates from multi-vehicle clients disappearing under load); the fix has been running in that fork for weeks of sessions.
Transparency
This fix comes from an AI-assisted fork: the bug was found and the patch written with the help of an AI coding tool (Claude), then tested by a human in real multiplayer sessions. Given this project's policy on AI-generated code, it's submitted as a draft for the maintainers to decide — happy to close it if that's not wanted, or for a maintainer to re-implement the one-liner independently.
🤖 Generated with Claude Code