拆分包分成2包用pcapdotnet(Split packet into 2 packets wit

我怎样才能使用pcapdotnet拆分一个包分成两个包？这是我试过，但我不知道它是否是正确的：

    public IEnumerable<Packet> splitPacket(Packet packet)
    {
        EthernetLayer ethernet = (EthernetLayer)packet.Ethernet.ExtractLayer();
        IpV4Layer ipV4Layer = (IpV4Layer)packet.Ethernet.IpV4.ExtractLayer();
        DateTime packetTimestamp = packet.Timestamp;
        ILayer payload = packet.Ethernet.IpV4.Payload.ExtractLayer();
        IpV4Fragmentation.Equals(packet, packet);

        yield return PacketBuilder.Build(packetTimestamp, ethernet, ipV4Layer, payload);
    }

我从来没有使用Pcap.Net，所以我不知道这是否会工作，但总的想法是将数据（“有效载荷层”）拆分成若干块，然后将其发送。为了确保该片段可以被重新组装，您还需要添加有关每个片段的位置（偏移）的一些信息。

在Pcap.Net中， IpV4Fragmentation类里包含了这两个属性：

IpV4Fragmentation.Options ：
- 对于除塔最后一个的所有片段，它应被设置为IpV4FragmentationOptions.MoreFragments ，
- 对于最后一个片段，它应被设置为IpV4FragmentationOptions.None
IpV4Fragmentation.Offset ：
- 的片段（其必须是8的倍数）的包含的偏移。该偏移是用于第一片段为零。

考虑到这一点，我会写这样的事情：

（免责声明：本写在记事本中，我不知道如果它甚至编译，更不用说工作，因为它应该）：

public IEnumerable<Packet> Split(Packet packet, int numberOfFragments)
{
    // get original layers
    var ethernet = (EthernetLayer)packet.Ethernet.ExtractLayer();
    var ipV4 = (IpV4Layer)packet.Ethernet.IpV4.ExtractLayer();
    var time = packet.Timestamp;

    // extract the data
    var payload = (PayloadLayer)packet.Ethernet.IpV4.Payload.ExtractLayer();
    var totalLength = payload.Length;

    // split data into smaller segments
    var partialLength = totalLength / numberOfFragments;

    // make sure it's divisible with 8
    // (see http://en.wikipedia.org/wiki/IPv4#Fragmentation_and_reassembly)
    partialLength = (partialLength / 8) * 8;

    // send one by one
    var offset = 0;
    while (offset < totalLength)
    {
        // get length for this fragment
        var fragmentLength = partialLength;
        var options = IpV4FragmentationOptions.MoreFragments;            

        // is this the last fragment? trim length if needed
        if (offset + fragmentLength >= totalLength) 
        {
            options = IpV4FragmentationOptions.None;
            fragmentLength = totalLength - offset;
        }

        // copy the actual data into a new buffer
        var newBuffer = payload.ReadBytes(offset, fragmentLength);
        var newPayload = new PayloadLayer() { Data = newBuffer };

        // change IP layer fragmentation options
        ipV4.Fragmentation = new IpV4Fragmentation(options, offset);

        // return it
        yield return PacketBuilder.Build(time, ethernet, ipV4, newPayload);

        // next offset
        offset += fragmentLength;
    }
}

[更新了@ brickner的建议]