fix(rx): reject undersized typed frames safely

tests/run_host_tests.ps1

@@ -0,0 +1,38 @@
+$ErrorActionPreference = 'Stop'
+
+$repo = Split-Path -Parent $PSScriptRoot
+$build = Join-Path $PSScriptRoot '.build'
+New-Item -ItemType Directory -Force -Path $build | Out-Null
+
+$compiler = if (Test-Path -LiteralPath 'C:\MinGW\bin\g++.exe') {
+    'C:\MinGW\bin\g++.exe'
+} else {
+    (Get-Command g++ -ErrorAction Stop).Source
+}
+
+$common = @(
+    '-std=c++17', '-Wall', '-Wextra', '-Werror',
+    '-Wno-unused-parameter', '-Wno-ignored-qualifiers', '-Wno-sign-compare',
+    '-I', (Join-Path $PSScriptRoot 'arduino_stubs'),
+    '-I', $repo
+)
+
+& $compiler @common `
+    (Join-Path $PSScriptRoot 'test_timing_contract.cpp') `
+    (Join-Path $repo 'IR_Encoder.cpp') `
+    (Join-Path $repo 'IR_config.cpp') `
+    '-o' (Join-Path $build 'test_timing_contract.exe')
+if ($LASTEXITCODE -ne 0) { throw 'timing test build failed' }
+
+& (Join-Path $build 'test_timing_contract.exe')
+if ($LASTEXITCODE -ne 0) { throw 'timing test failed' }
+
+& $compiler @common `
+    (Join-Path $PSScriptRoot 'test_packet_types.cpp') `
+    (Join-Path $repo 'PacketTypes.cpp') `
+    (Join-Path $repo 'IR_config.cpp') `
+    '-o' (Join-Path $build 'test_packet_types.exe')
+if ($LASTEXITCODE -ne 0) { throw 'packet test build failed' }
+
+& (Join-Path $build 'test_packet_types.exe')
+if ($LASTEXITCODE -ne 0) { throw 'packet test failed' }

tests/test_packet_types.cpp

@@ -0,0 +1,145 @@
+#include "PacketTypes.h"
+
+#include <array>
+#include <cassert>
+#include <cstdint>
+#include <iostream>
+
+namespace
+{
+template <typename Packet>
+class ExposedPacket : public Packet
+{
+public:
+    void attach(IR_FOX::PackInfo *info, uint16_t id = 0U)
+    {
+        this->set(info, id);
+    }
+};
+
+IR_FOX::PackInfo makeFrame(uint8_t *buffer, uint8_t msgType, uint8_t wireBytes)
+{
+    buffer[0] = static_cast<uint8_t>((msgType << 5) | (wireBytes & IR_MASK_MSG_INFO));
+    IR_FOX::PackInfo result;
+    result.buffer = buffer;
+    result.packSize = wireBytes;
+    return result;
+}
+
+template <typename Packet>
+void verifyMinimum(uint8_t msgType, uint8_t minimum)
+{
+    std::array<uint8_t, irproto::kMaxWireFrameBytes> buffer{};
+    ExposedPacket<Packet> packet;
+
+    IR_FOX::PackInfo shortFrame = makeFrame(buffer.data(), msgType, minimum - 1U);
+    packet.attach(&shortFrame);
+    assert(!packet.available());
+    assert(!packet.availableRaw());
+
+    IR_FOX::PackInfo minimumFrame = makeFrame(buffer.data(), msgType, minimum);
+    packet.attach(&minimumFrame);
+    assert(packet.available());
+}
+
+void verifyTypedMinimums()
+{
+    verifyMinimum<PacketTypes::Data>(IR_MSG_DATA_ACCEPT, 7U);
+    verifyMinimum<PacketTypes::Data>(IR_MSG_DATA_NOACCEPT, 7U);
+    verifyMinimum<PacketTypes::DataBack>(IR_MSG_BACK, 5U);
+    verifyMinimum<PacketTypes::DataBack>(IR_MSG_BACK_TO, 7U);
+    verifyMinimum<PacketTypes::Accept>(IR_MSG_ACCEPT, 6U);
+    verifyMinimum<PacketTypes::Request>(IR_MSG_REQUEST, 7U);
+}
+
+void verifyDataAccessCannotUnderflow()
+{
+    std::array<uint8_t, irproto::kMaxWireFrameBytes> buffer{};
+    ExposedPacket<PacketTypes::Data> data;
+
+    for (uint8_t wireBytes = 0U; wireBytes < irproto::kDataFrameOverheadBytes; ++wireBytes)
+    {
+        IR_FOX::PackInfo malformed = makeFrame(buffer.data(), IR_MSG_DATA_ACCEPT, wireBytes);
+        data.attach(&malformed);
+        assert(!data.available());
+        assert(data.getDataSize() == 0U);
+        assert(data.getDataPrt() == nullptr);
+        assert(data.getAddrTo() == 0U);
+    }
+
+    IR_FOX::PackInfo empty = makeFrame(buffer.data(), IR_MSG_DATA_ACCEPT, 7U);
+    data.attach(&empty);
+    assert(data.available());
+    assert(data.getDataSize() == 0U);
+    assert(data.getDataPrt() == buffer.data() + 5U);
+
+    IR_FOX::PackInfo oneByte = makeFrame(buffer.data(), IR_MSG_DATA_ACCEPT, 8U);
+    data.attach(&oneByte);
+    assert(data.available());
+    assert(data.getDataSize() == 1U);
+    assert(data.getDataPrt() == buffer.data() + 5U);
+}
+
+void verifyBackLayouts()
+{
+    std::array<uint8_t, irproto::kMaxWireFrameBytes> buffer{};
+    ExposedPacket<PacketTypes::DataBack> back;
+
+    IR_FOX::PackInfo shortBroadcast = makeFrame(buffer.data(), IR_MSG_BACK, 4U);
+    back.attach(&shortBroadcast);
+    assert(!back.available());
+    assert(back.getDataSize() == 0U);
+    assert(back.getDataPrt() == nullptr);
+
+    IR_FOX::PackInfo broadcast = makeFrame(buffer.data(), IR_MSG_BACK, 5U);
+    back.attach(&broadcast);
+    assert(back.available());
+    assert(back.getDataSize() == 0U);
+    assert(back.getDataPrt() == buffer.data() + 3U);
+
+    IR_FOX::PackInfo shortAddressed = makeFrame(buffer.data(), IR_MSG_BACK_TO, 6U);
+    back.attach(&shortAddressed);
+    assert(!back.available());
+    assert(back.getDataSize() == 0U);
+
+    IR_FOX::PackInfo addressed = makeFrame(buffer.data(), IR_MSG_BACK_TO, 7U);
+    back.attach(&addressed);
+    assert(back.available());
+    assert(back.getDataSize() == 0U);
+    assert(back.getDataPrt() == buffer.data() + 5U);
+}
+
+void verifyRawAndHeaderContracts()
+{
+    std::array<uint8_t, irproto::kMaxWireFrameBytes> buffer{};
+    ExposedPacket<PacketTypes::BasePack> raw;
+
+    // Raw diagnostics remain able to observe a CRC-sized frame even when its
+    // declared type-specific layout is too short.
+    IR_FOX::PackInfo shortTyped = makeFrame(buffer.data(), IR_MSG_DATA_ACCEPT, 3U);
+    raw.attach(&shortTyped);
+    assert(raw.availableRaw());
+
+    IR_FOX::PackInfo inconsistent = makeFrame(buffer.data(), IR_MSG_BACK, 5U);
+    inconsistent.packSize = 6U;
+    raw.attach(&inconsistent);
+    assert(!raw.available());
+    assert(!raw.availableRaw());
+
+    IR_FOX::PackInfo nullFrame;
+    nullFrame.packSize = 31U;
+    raw.attach(&nullFrame);
+    assert(!raw.available());
+    assert(!raw.availableRaw());
+}
+}
+
+int main()
+{
+    verifyTypedMinimums();
+    verifyDataAccessCannotUnderflow();
+    verifyBackLayouts();
+    verifyRawAndHeaderContracts();
+    std::cout << "IR packet boundary tests: OK\n";
+    return 0;
+}