Packet增加Slice方法

xljiulang · Oct 28, 2022 · b72aeac · b72aeac
1 parent da1c6b2
commit b72aeac
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Showing 2 changed files with 65 additions and 4 deletions.
diff --git a/WindivertDotnet.Test/WinDivertPacketTest.cs b/WindivertDotnet.Test/WinDivertPacketTest.cs
@@ -39,6 +39,24 @@ public void GetSpanTest()
             Assert.Throws<ArgumentOutOfRangeException>(() => packet.GetSpan(1, 10));
         }
 
+
+        [Fact]
+        public void SliceTest()
+        {
+            using var packet = new WinDivertPacket(10);
+            var slicePacket = packet.Slice(2, 8);
+
+            var span = packet.GetSpan(0, packet.Capacity);
+            span[1] = 1;
+            span[2] = 2;
+            span[4] = 4;
+            span[8] = 8;
+
+            Assert.Equal(8, slicePacket.Capacity);
+            Assert.Equal(8, slicePacket.Length);
+            Assert.True(span.Slice(2, 8).SequenceEqual(slicePacket.Span));
+        }
+
         [Fact]
         public unsafe void CalcNetworkIfIdxTest()
         {

diff --git a/WindivertDotnet/WinDivertPacket.cs b/WindivertDotnet/WinDivertPacket.cs
@@ -36,7 +36,7 @@ public class WinDivertPacket : SafeHandleZeroOrMinusOneIsInvalid, IEquatable<Win
         /// <summary>
         /// 获取有效数据视图
         /// </summary>
-        public Span<byte> Span => this.GetSpan(0, this.length);
+        public unsafe Span<byte> Span => new(this.handle.ToPointer(), this.length);
 
         /// <summary>
         /// 获取或设置有效数据的长度
@@ -60,12 +60,25 @@ public int Length
         /// </summary>
         /// <param name="capacity">最大容量</param> 
         public WinDivertPacket(int capacity = MTU_MAX)
-            : base(ownsHandle: true)
+            : this(MemoryNative.AllocZeroed(capacity), capacity, ownsHandle: true)
         {
             this.Capacity = capacity;
             this.handle = MemoryNative.AllocZeroed(capacity);
         }
 
+        /// <summary>
+        /// WinDivert的数据包
+        /// </summary>
+        /// <param name="handle"></param>
+        /// <param name="capacity"></param>
+        /// <param name="ownsHandle"></param>
+        private unsafe WinDivertPacket(IntPtr handle, int capacity, bool ownsHandle)
+            : base(ownsHandle)
+        {
+            this.handle = handle;
+            this.Capacity = capacity;
+        }
+
         /// <summary>
         /// 释放本机句柄
         /// </summary>
@@ -89,8 +102,39 @@ public void Clear()
         /// </summary>
         /// <param name="offset">偏移量</param>
         /// <param name="count">字节数</param>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
         /// <returns></returns>
         public unsafe Span<byte> GetSpan(int offset, int count)
+        {
+            var pointer = this.GetPointer(offset, count);
+            return new Span<byte>(pointer, count);
+        }
+
+        /// <summary>
+        /// 切片
+        /// </summary>
+        /// <param name="offset">偏移量</param>
+        /// <param name="count">大小</param>
+        /// <returns></returns>
+        public unsafe WinDivertPacket Slice(int offset, int count)
+        {
+            var pointer = this.GetPointer(offset, count);
+            var handle = new IntPtr(pointer);
+            return new WinDivertPacket(handle, count, ownsHandle: false)
+            {
+                length = count
+            };
+        }
+
+
+        /// <summary>
+        /// 获取指针
+        /// </summary>
+        /// <param name="offset"></param>
+        /// <param name="count"></param>
+        /// <returns></returns>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        private unsafe void* GetPointer(int offset, int count)
         {
             if (offset < 0 || offset > this.Capacity)
             {
@@ -102,8 +146,7 @@ public unsafe Span<byte> GetSpan(int offset, int count)
                 throw new ArgumentOutOfRangeException(nameof(count));
             }
 
-            var pointer = (byte*)this.handle.ToPointer() + offset;
-            return new Span<byte>(pointer, count);
+            return (this.handle + offset).ToPointer();
         }
 
         /// <summary>