通过IPIP.NET实现数据库来查询IP地址的实例

IPIP所提供的数据库有付费和免费两个版本，我们可以直接使用其中的免费版本。下载地址 https://www.ipip.net/download.html （需要先注册一个帐号）压缩包内有一个PHP的解析类，还有一个 17monipdb.dat 文件就是数据库了，我们只需要用到它就可以了。

将 17monipdb.dat 复制到程序的主目录，使用下面的代码：

Imports System.IO  Imports System.Text    Public Class IPIP        Shared offset As Integer      Shared index As UInteger() = New UInteger(255) {}      Shared dataBuffer As Byte()      Shared indexBuffer As Byte()      Shared lastModifyTime As Long = 0L      Shared ipFile As String        Shared rwlock As New Threading.ReaderWriterLock          Shared Sub New()          Load("17monipdb.dat")      End Sub        Shared Sub Load(ByVal filename As String)          ipFile = New FileInfo(filename).FullName          Load()      End Sub        Shared Sub Load()          rwlock.AcquireWriterLock(-1)            Dim fi As New FileInfo(ipFile)          lastModifyTime = fi.LastWriteTime.Ticks            Try              dataBuffer = File.ReadAllBytes(fi.FullName)                Dim indexLength = BytesToLong(dataBuffer(0), dataBuffer(1), dataBuffer(2), dataBuffer(3))              indexBuffer = New Byte(indexLength - 1) {}              Array.Copy(dataBuffer, 4, indexBuffer, 0, indexLength)              offset = CType(indexLength, Integer)                            For lp As Integer = 0 To 255                    index(lp) = BytesToLong( _                   indexBuffer(lp * 4 + 3), _                   indexBuffer(lp * 4 + 2), _                   indexBuffer(lp * 4 + 1), _                   indexBuffer(lp * 4) _                   )                Next            Catch ex As Exception              Throw ex          End Try            rwlock.ReleaseWriterLock()      End Sub              Private Shared Function BytesToLong(ByVal a As Byte, ByVal b As Byte, ByVal c As Byte, ByVal d As Byte) As UInteger          Return (CType(a, UInteger) << 24) Or (CType(b, UInteger) << 16) Or (CType(c, UInteger) << 8) Or d      End Function          Shared Function Find(ByVal ip As String) As String()          rwlock.AcquireReaderLock(-1)            Dim ips = ip.Split(".")          Dim ip_prefix_value = Integer.Parse(ips(0))          Dim ip2long_value As Long = BytesToLong(Byte.Parse(ips(0)), Byte.Parse(ips(1)), Byte.Parse(ips(2)), Byte.Parse(ips(3)))          Dim start = index(ip_prefix_value)          Dim max_comp_len = offset - 1028            Dim index_offset As Long = -1L          Dim index_length As Integer = -1          Dim b As Byte = 0            start = start * 8 + 1024          While start < max_comp_len              If BytesToLong(indexBuffer(start + 0), indexBuffer(start + 1), indexBuffer(start + 2), indexBuffer(start + 3)) >= ip2long_value Then                  index_offset = BytesToLong(b, indexBuffer(start + 6), indexBuffer(start + 5), indexBuffer(start + 4))                  index_length = &HFF And indexBuffer(start + 7)                  Exit While              End If              start += 8          End While            Dim areaBytes = New Byte(index_length - 1) {}          Array.Copy(dataBuffer, offset + index_offset - 1024, areaBytes, 0, index_length)            Dim ret As String() = Encoding.UTF8.GetString(areaBytes).Split(vbTab)            rwlock.ReleaseReaderLock()            Return ret      End Function        End Class

使用方法很简单：

Dim ret = IPIP.Find("127.0.0.1"  ' 用换行分隔所有信息  Dim ipdesc = String.Join(vbCrLf, ret)

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