niko
46 lines
2.1 KiB
Markdown
46 lines
2.1 KiB
Markdown
# Patches applied to vendored submodules
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## `0001-tachyon-packet-layer-hook.patch` → `vendor/LiteNetLibPP`
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Applies to: LiteNetLibPP @ `c6625b0652c5930046b75b495db314456c8bc411`
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(https://github.com/Revan600/LiteNetLibPP), the pinned submodule under `vendor/LiteNetLibPP`.
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### Why
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Upstream has no packet-layer abstraction, but the Rec Room client wraps every datagram in a
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trailing-marker "encrypt" layer (a `0x11` byte on the plaintext path). This patch adds a generic
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datagram-transform hook — the equivalent of the C# LiteNetLib `PacketLayerBase` — so Tachyon can
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install the marker without forking the library wholesale. It is deliberately generic (not
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RecRoom-specific) so it could be submitted upstream unchanged.
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### What it changes
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- `include/lnl/net_manager.h` — two public `std::function` members, `outbound_layer` and
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`inbound_layer` (both default null → stock behaviour), plus `<functional>`/`<vector>` includes.
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- `src/lnl/net_manager.cpp`
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- `send_raw()` — if `outbound_layer` is set, transform the bytes just before `sendto`.
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- `receive_logic()` — if `inbound_layer` is set, transform/drop each datagram just after
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`recvfrom`, before `on_message_received`.
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Tachyon installs the `0x11` marker through these hooks in `src/main.cpp`.
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### How it is applied
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The top-level `CMakeLists.txt` applies this patch to the submodule working tree at configure time,
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idempotently (`git apply --reverse --check` detects an already-patched tree and skips). This leaves
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the submodule showing as "dirty" in `git status` — that is expected. To reset it:
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`git -C vendor/LiteNetLibPP checkout .`
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### Regenerating the patch (if the pin is bumped)
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```sh
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# from a pristine checkout of the new upstream commit, with the two files edited:
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git -C <litenetlibpp> diff > patches/0001-tachyon-packet-layer-hook.patch
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```
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### Known limitation
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The outbound hook appends its marker *after* LiteNetLibPP's MTU/fragmentation math, without
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reserving space the way the C# `ExtraPacketSizeForLayer` did. Safe here because every packet the
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server *sends* is far below the MTU; revisit if the server ever sends reliable data near the MTU.
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