问BPF过滤器不适用于vlan数据包

EN

pcpp::IFileReaderDevice* reader = pcpp::IFileReaderDevice::getReader("input.pcap");

// verify that a reader interface was indeed created
if (reader == NULL)
{   
    printf("Cannot determine reader for file type\n");
    exit(1);
}   

// open the reader for reading
if (!reader->open())
{   
    printf("Cannot open input.pcap for reading\n");
    exit(1);
}   

// create a pcap file writer. Specify file name and link type of all packets that
// will be written to it
pcpp::PcapFileWriterDevice pcapWriter("output.pcap", pcpp::LINKTYPE_ETHERNET);

// try to open the file for writing
if (!pcapWriter.open())
{   
    printf("Cannot open output.pcap for writing\n");
    exit(1);
}   

// create a pcap-ng file writer. Specify file name. Link type is not necessary because
// pcap-ng files can store multiple link types in the same file
pcpp::PcapNgFileWriterDevice pcapNgWriter("output.pcapng");

// try to open the file for writing
if (!pcapNgWriter.open())
{   
    printf("Cannot open output.pcapng for writing\n");
    exit(1);
}   

// set a BPF filter for the reader - only packets that match the filter will be read
if (!reader->setFilter("tcp"))
{   
    printf("Cannot set filter for file reader\n");
    exit(1);
}   

// the packet container
pcpp::RawPacket rawPacket;

// a while loop that will continue as long as there are packets in the input file
// matching the BPF filter
while (reader->getNextPacket(rawPacket))
{
    // write each packet to both writers
    printf("matched ...\n");
    pcapWriter.writePacket(rawPacket);
    pcapNgWriter.writePacket(rawPacket);
}