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POMarshalling IntPtrs within structs in C#
 

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  1. POMarshalling IntPtrs within structs in C#
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    <p>I intend to model a C# class for parsing custom protocol data I receive as a raw buffer. The buffer is already at hand as a byte array. </p> <p>This parser has to cope with varying field layouts, hence some of the protocol elements are IntPtrs.</p> <p>When I try to access a pointer within a struct after mapping the raw buffer into it, I run into an access violation.</p> <p>I made up a simple example which shows the crucial part:</p> <pre><code>namespace CS_StructMarshalling { class Packet { public PacketStruct Fields; [StructLayout(LayoutKind.Explicit)] public struct PacketStruct { [FieldOffset(0)] public UInt16 Flags; [FieldOffset(2)] public IntPtr Data; } public Packet() { Fields = new PacketStruct(); } public void DecompileBinaryBuffer(ref Byte[] byteBuffer) { int size = Marshal.SizeOf(typeof(PacketStruct)); IntPtr ptr = Marshal.AllocHGlobal(size); Marshal.Copy(byteBuffer, 0, ptr, size); this.Fields = (PacketStruct)Marshal.PtrToStructure(ptr, typeof(PacketStruct)); Marshal.FreeHGlobal(ptr); } } class Program { static void Main(string[] args) { byte[] rawBuffer = new byte[] { 1, 2, 65, 66, 67, 68, 69, 70 }; Packet testPkt = new Packet(); testPkt.DecompileBinaryBuffer(ref rawBuffer); UInt16 testFlags = testPkt.Fields.Flags; String testData = Marshal.PtrToStringAnsi(testPkt.Fields.Data, 6); } } } </code></pre> <p>I just try to wrap my head around this issue, but to no avail. To my understanding, the IntPtr must be marshalled seperately, but I don't find any hints how this could be done in a clean way.</p> <p>Any pointers welcome. Thank you for your time.</p>
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    1. USmarsch
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    1. COSending an `IntPtr` is doomed; that ***cannot ever work***. However; it looks like you are just trying to serialize some data; have you considered pre-rolled binary serialization APIs such as protobuf-net?
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      1. USMarc Gravell
 

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