AB CIP UDT Template Object shape reader. Closes the shape-reader half of task #179. CipTemplateObjectDecoder (pure-managed) parses the Read Template blob per Rockwell CIP Vol 1 + libplctag ab/cip.c handle_read_template_reply — 12-byte header (u16 member_count + u16 struct_handle + u32 instance_size + u32 member_def_size) followed by memberCount × 8-byte member blocks (u16 info with bit-15 struct flag + lower-12-bit type code matching the Symbol Object encoding, u16 array_size, u32 struct_offset) followed by semicolon-terminated strings (UDT name first, then one per member). ParseSemicolonTerminatedStrings handles the observed firmware variations — name;\0 vs name; delimiters, optional null/space padding after the semicolon, trailing-name-without-semicolon corner case. Struct-flag members decode as AbCipDataType.Structure; unknown atomic codes fall back to Structure so the shape remains valid even with unrecognised members. Zero member count + short buffer both return null; missing member names yield <member_N> placeholders. IAbCipTemplateReader + IAbCipTemplateReaderFactory abstraction — one call per template instance id returning the raw blob. LibplctagTemplateReader is the production implementation creating a libplctag Tag with name @udt/{templateId} + handing the buffer to the decoder. AbCipDriver ctor gains optional templateReaderFactory parameter (defaults to LibplctagTemplateReaderFactory) + new internal FetchUdtShapeAsync that — checks AbCipTemplateCache first, misses call the reader + decode + cache, template-read exceptions + decode failures return null so callers can fall back to declaration-driven fan-out without the whole discovery blowing up. OperationCanceledException rethrows for shutdown propagation. Unknown device host returns null without attempting a fetch. FlushOptionalCachesAsync empties the cache so a subsequent fetch re-reads. 16 new decoder tests — simple two-member UDT, struct-member flag → Structure, array member ArrayLength, 6-member mixed-type with correct offsets, unknown type code → Structure, zero member count → null, short buffer → null, missing member name → placeholder, ParseSemicolonTerminatedStrings theory across 5 shapes. 6 new AbCipFetchUdtShapeTests exercising the driver integration via reflection (method is internal) — happy-path decode + cache, different template ids get separate fetches, unknown device → null without reader creation, decode failure returns null + doesn't cache (next call retries), reader exception returns null, FlushOptionalCachesAsync clears the cache. Total AbCip unit tests now 211/211 passing (+19 from the @tags merge's 192); full solution builds 0 errors; other drivers untouched. Whole-UDT read optimization (single libplctag call returning the packed buffer + client-side member decode using the template offsets) is left as a follow-up — requires rethinking the per-tag read path + careful hardware validation; current per-member fan-out still works correctly, just with N round-trips instead of 1.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Joseph Doherty
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using System.Buffers.Binary;
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using System.Reflection;
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using System.Text;
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using Shouldly;
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using Xunit;
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using ZB.MOM.WW.OtOpcUa.Driver.AbCip;
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namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests;
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[Trait("Category", "Unit")]
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public sealed class AbCipFetchUdtShapeTests
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{
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private sealed class FakeTemplateReader : IAbCipTemplateReader
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{
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public byte[] Response { get; set; } = [];
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public int ReadCount { get; private set; }
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public bool Disposed { get; private set; }
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public uint LastTemplateId { get; private set; }
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public Task<byte[]> ReadAsync(AbCipTagCreateParams deviceParams, uint templateInstanceId, CancellationToken ct)
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{
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ReadCount++;
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LastTemplateId = templateInstanceId;
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return Task.FromResult(Response);
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}
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public void Dispose() => Disposed = true;
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}
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private sealed class FakeTemplateReaderFactory : IAbCipTemplateReaderFactory
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{
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public List<IAbCipTemplateReader> Readers { get; } = new();
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public Func<IAbCipTemplateReader>? Customise { get; set; }
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public IAbCipTemplateReader Create()
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{
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var r = Customise?.Invoke() ?? new FakeTemplateReader();
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Readers.Add(r);
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return r;
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}
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}
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private static byte[] BuildSimpleTemplate(string name, uint instanceSize, params (string n, ushort info, ushort arr, uint off)[] members)
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{
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var headerSize = 12;
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var blockSize = 8;
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var strings = new MemoryStream();
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void Add(string s) { var b = Encoding.ASCII.GetBytes(s + ";\0"); strings.Write(b, 0, b.Length); }
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Add(name);
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foreach (var m in members) Add(m.n);
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var stringsArr = strings.ToArray();
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var buf = new byte[headerSize + blockSize * members.Length + stringsArr.Length];
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BinaryPrimitives.WriteUInt16LittleEndian(buf.AsSpan(0), (ushort)members.Length);
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BinaryPrimitives.WriteUInt16LittleEndian(buf.AsSpan(2), 0x1234);
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BinaryPrimitives.WriteUInt32LittleEndian(buf.AsSpan(4), instanceSize);
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for (var i = 0; i < members.Length; i++)
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{
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var o = headerSize + i * blockSize;
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BinaryPrimitives.WriteUInt16LittleEndian(buf.AsSpan(o), members[i].info);
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BinaryPrimitives.WriteUInt16LittleEndian(buf.AsSpan(o + 2), members[i].arr);
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BinaryPrimitives.WriteUInt32LittleEndian(buf.AsSpan(o + 4), members[i].off);
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}
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Buffer.BlockCopy(stringsArr, 0, buf, headerSize + blockSize * members.Length, stringsArr.Length);
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return buf;
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}
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private static Task<AbCipUdtShape?> InvokeFetch(AbCipDriver drv, string deviceHostAddress, uint templateId)
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{
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var mi = typeof(AbCipDriver).GetMethod("FetchUdtShapeAsync",
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BindingFlags.NonPublic | BindingFlags.Instance)!;
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return (Task<AbCipUdtShape?>)mi.Invoke(drv, [deviceHostAddress, templateId, CancellationToken.None])!;
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}
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[Fact]
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public async Task FetchUdtShapeAsync_decodes_blob_and_caches_result()
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{
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var factory = new FakeTemplateReaderFactory
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{
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Customise = () => new FakeTemplateReader
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{
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Response = BuildSimpleTemplate("MotorUdt", 8,
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("Speed", 0xC4, 0, 0),
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("Enabled", 0xC1, 0, 4)),
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},
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};
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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var shape = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 42);
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shape.ShouldNotBeNull();
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shape.TypeName.ShouldBe("MotorUdt");
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shape.Members.Count.ShouldBe(2);
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// Second fetch must hit the cache — no second reader created.
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_ = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 42);
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factory.Readers.Count.ShouldBe(1);
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}
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[Fact]
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public async Task FetchUdtShapeAsync_different_templateIds_each_fetch()
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{
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var callCount = 0;
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var factory = new FakeTemplateReaderFactory
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{
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Customise = () =>
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{
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callCount++;
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var name = callCount == 1 ? "UdtA" : "UdtB";
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return new FakeTemplateReader
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{
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Response = BuildSimpleTemplate(name, 4, ("X", 0xC4, 0, 0)),
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};
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},
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};
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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var a = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 1);
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var b = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 2);
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a!.TypeName.ShouldBe("UdtA");
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b!.TypeName.ShouldBe("UdtB");
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factory.Readers.Count.ShouldBe(2);
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}
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[Fact]
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public async Task FetchUdtShapeAsync_unknown_device_returns_null()
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{
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var factory = new FakeTemplateReaderFactory();
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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var shape = await InvokeFetch(drv, "ab://10.0.0.99/1,0", 1);
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shape.ShouldBeNull();
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factory.Readers.ShouldBeEmpty();
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}
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[Fact]
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public async Task FetchUdtShapeAsync_decode_failure_returns_null_and_does_not_cache()
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{
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var factory = new FakeTemplateReaderFactory
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{
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Customise = () => new FakeTemplateReader { Response = [0x00, 0x00] }, // too short
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};
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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var shape = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 1);
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shape.ShouldBeNull();
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// Next call retries (not cached as a failure).
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var shape2 = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 1);
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shape2.ShouldBeNull();
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factory.Readers.Count.ShouldBe(2);
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}
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[Fact]
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public async Task FetchUdtShapeAsync_reader_exception_returns_null()
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{
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var factory = new FakeTemplateReaderFactory
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{
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Customise = () => new ThrowingTemplateReader(),
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};
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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var shape = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 1);
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shape.ShouldBeNull();
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}
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[Fact]
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public async Task FlushOptionalCachesAsync_empties_template_cache()
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{
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var factory = new FakeTemplateReaderFactory
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{
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Customise = () => new FakeTemplateReader
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{
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Response = BuildSimpleTemplate("U", 4, ("X", 0xC4, 0, 0)),
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},
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};
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var drv = new AbCipDriver(new AbCipDriverOptions
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{
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Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
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}, "drv-1", templateReaderFactory: factory);
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await drv.InitializeAsync("{}", CancellationToken.None);
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_ = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 99);
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drv.TemplateCache.Count.ShouldBe(1);
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await drv.FlushOptionalCachesAsync(CancellationToken.None);
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drv.TemplateCache.Count.ShouldBe(0);
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// Next fetch hits the network again.
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_ = await InvokeFetch(drv, "ab://10.0.0.5/1,0", 99);
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factory.Readers.Count.ShouldBe(2);
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}
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private sealed class ThrowingTemplateReader : IAbCipTemplateReader
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{
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public Task<byte[]> ReadAsync(AbCipTagCreateParams p, uint id, CancellationToken ct) =>
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throw new InvalidOperationException("fake read failure");
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public void Dispose() { }
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}
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}
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