Question

我想发送一个UDP数据包，其结构如下

数据包大小为8个字节
uint16数据类型的标题字段
uint16数据类型的命令字段
uint32数据类型的数字字段

我按照以下方式设计了数据包：

ushort header = (ushort)IPAddress.HostToNetworkOrder(0x0001);
ushort command = (ushort)IPAddress.HostToNetworkOrder(10);
uint number = (uint)IPAddress.HostToNetworkOrder(2);

byte[] requestPacket = new byte[8];
requestPacket[0] = (byte)(header >> 8 & 0xFF);
requestPacket[1] = (byte)(header & 0xFF);
requestPacket[2] = (byte)(command >> 8 & 0xFF);
requestPacket[3] = (byte)(command & 0xFF);
requestPacket[4] = (byte)(number >> 24 & 0xFF);
requestPacket[5] = (byte)(number >> 16 & 0xFF);
requestPacket[6] = (byte)(number >> 8 & 0xFF);
requestPacket[7] = (byte)(number & 0xFF);

是否有更好的方法与上述相同？

Answer 1

您可以使用BitConverter例如：

var headerBytes = BitConverter.GetBytes(header);
Array.Copy(headerBytes, 0, requestPacket, 0, 2);

Answer 2

您还可以使用.NET的内置编组功能或不安全的代码：

[StructLayout(LayoutKind.Sequential, Pack = 1)] // Ensure tight packing
public struct Packet
{
    public ushort Header;
    public ushort Command;
    public uint Number;
}

Packet packet = new Packet { ... };
byte[] packetData = new byte[Marshal.Sizeof<Packet>()];

// Using marshaling
var handle = default(GCHandle);
try
{
    handle = GCHandle.Alloc(packetData, GCHandleType.Pinned);
    Marshal.StructureToPtr(packet, handle.AddrOfPinnedObject(), fDeleteOld: false);
}
finally
{
    if (handle.IsAllocated) handle.Free();
}

// Using unsafe code (careful, assumes marshaled size == size in memory!)
unsafe { fixed(byte* packedPtr = packetData) *(Packet*)packedPtr = packet; }

但是，这两种解决方案都会使用本地计算机字节序编码您的字段。这对您来说可能是也可能不是问题。

C＃中的自定义UDP数据包结构

2 个答案: