如何使用mDNS进行Pcap.net查询？

Question

问题：--我正在寻找一个mDNS包，同时在堆栈流中搜索选项。我尝试了bonjour和一些包装器，但是取得了非常有限的成功，特别是当我第二次请求并收到套接字绑定投诉时(当然，这可能是我的代码而不是它们)。

因为据我所知，VB.net没有一个真正可编辑的DNS层，所以我在pcapdotnet中使用构建DNS包中的DNS层，并且只是一层一层地制作包。我认为这是一个很好的选择，但我有点不知道该怎么做。

以下是我们想要的问题：

        q_name = new QuestionName("_axis-video._tcp.local"),
        q_type = QueryConstants.Question.QuestionType.PTR,
        q_class = QueryConstants.Question.QuestionClass.IN

下面是我根据标准编辑的BuildDNSPacket函数：

Private Shared Function BuildDnsPacket(destmac As String, domainName As String) As Packet

    'get source MAC address of PC
    Dim nic = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces()
    Dim source As String = nic(0).GetPhysicalAddress().ToString
    Dim sourcearray As Byte() = System.Text.Encoding.ASCII.GetBytes(source)

    'format
    Dim sourceMacStr As String = ""
    For i As Integer = 0 To sourcearray.Count - 1 Step 2
        sourceMacStr += Chr(sourcearray(i)) & Chr(sourcearray(i + 1)) & ":"
    Next

    ' Will be filled automatically.
    Dim ethernetLayer As New EthernetLayer() With { _
         .Source = New MacAddress(sourceMacStr.Substring(0, 17)), _
          .Destination = New MacAddress(destmac), _
          .EtherType = EthernetType.None _
    }

    ' Will be filled automatically.
    Dim ipV4Layer As New IpV4Layer() With { _
          .Source = New IpV4Address("1.2.3.4"), _
          .CurrentDestination = New IpV4Address(destmac), _
          .Fragmentation = IpV4Fragmentation.None, _
          .HeaderChecksum = Nothing, _
          .Identification = 123, _
          .Options = IpV4Options.None, _
          .Protocol = Nothing, _
          .Ttl = 100, _
          .TypeOfService = 0 _
    }

    ' Will be filled automatically.
    Dim udpLayer As New UdpLayer() With { _
          .SourcePort = 5353, _
          .DestinationPort = 5353, _
          .Checksum = Nothing, _
          .CalculateChecksumValue = False _
    }

    Dim dnsLayer As New DnsLayer() With { _
          .Id = 0, _
          .IsResponse = False, _
          .OpCode = DnsOpCode.Query, _
          .IsAuthoritativeAnswer = False, _
          .IsTruncated = False, _
          .IsRecursionDesired = False, _
          .IsRecursionAvailable = False, _
          .FutureUse = False, _
          .IsAuthenticData = False, _
          .IsCheckingDisabled = False, _
          .ResponseCode = DnsResponseCode.NoError, _
          .Queries = {New DnsQueryResourceRecord(New DnsDomainName(domainName), DnsType.Ptr, DnsClass.Any)}, _
          .Answers = Nothing, _
          .Authorities = Nothing, _
          .Additionals = Nothing, _
          .DomainNameCompressionMode = DnsDomainNameCompressionMode.All _
    }


    Dim builder As New PacketBuilder(ethernetLayer, ipV4Layer, udpLayer, dnsLayer)

    Return builder.Build(DateTime.Now)
End Function

主要的区别是我将DnsType更改为PTR，将端口更改为5353。

问题：，为了使它成为mDNS，我还应该添加或更改什么？我能在domainName里放些什么？我应该改变一下等级吗？

我们绝对欢迎所有或任何建议。

Answer 1

如果其他需要在mDNS中使用vb.net的人需要这样做，我将回答我的问题：

解决方案：--我不需要向DNS层添加任何内容就可以完成这项工作。我将DNS层更改为：

   Dim dnsLayer As New DnsLayer() With { _
          .Id = 0, _
          .IsResponse = False, _
          .OpCode = DnsOpCode.Query, _
          .IsAuthoritativeAnswer = False, _
          .IsTruncated = False, _
          .IsRecursionDesired = False, _
          .IsRecursionAvailable = False, _
          .FutureUse = False, _
          .IsAuthenticData = False, _
          .IsCheckingDisabled = False, _
          .ResponseCode = DnsResponseCode.NoError, _
          .Queries = {New DnsQueryResourceRecord(New DnsDomainName(domainName), DnsType.Ptr, DnsClass.Any)}, _
          .Answers = Nothing, _
          .Authorities = Nothing, _
          .Additionals = Nothing, _
          .DomainNameCompressionMode = DnsDomainNameCompressionMode.All _
    }

我将Ipv4层的输出地址改为"224.0.0.251“的多播地址，将端口更改为5353，并使用了上述问题的域名。

这里有一个wireshark来展示你的回答：

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