'参考文档:http://lumaqq.linuxsir.org/article/qqwry_format_detail.html
'作者: gounliey
'Email:4473117@qq.com
'第一次写东西出来大家分享，还有很多不足之处，请大家指点。
'辅助类，用于保存IP索引信息
Public Class CZ_INDEX_INFO
Public IpSet As UInt32
Public IpEnd As UInt32
Public Offset As UInt32
Sub New()
IpSet = 0
IpEnd = 0
Offset = 0
End Sub
End Class
'读取纯真IP数据库类
Public Class PHCZIP
Protected bFilePathInitialized As Boolean
Protected FilePath As String
Protected FileStrm As FileStream
Protected Index_Set As UInt32
Protected Index_End As UInt32
Protected Index_Count As UInt32
Protected Search_Index_Set As UInt32
Protected Search_Index_End As UInt32
Protected Search_Set As CZ_INDEX_INFO
Protected Search_Mid As CZ_INDEX_INFO
Protected Search_End As CZ_INDEX_INFO
Public Sub New()
bFilePathInitialized = False
End Sub
Public Sub New(ByVal dbFilePath As String)
bFilePathInitialized = False
SetDbFilePath(dbFilePath)
End Sub
'使用二分法查找索引区，初始化查找区间
Protected Sub Initialize()
Search_Index_Set = 0
Search_Index_End = Index_Count - 1
End Sub
'关闭文件
Public Sub Dispose()
If (bFilePathInitialized) Then
bFilePathInitialized = False
FileStrm.Close()
FileStrm.Dispose()
End If
End Sub
'设置纯真IP数据库的文件路径
Public Function SetDbFilePath(ByVal dbFilePath As String) As Boolean
If (dbFilePath = "") Then
Return False
End If
'Try
'打开数据文件
FileStrm = New FileStream(dbFilePath, FileMode.Open, FileAccess.Read)
'Catch
'Return False
'End Try
'检查文件长度
If (FileStrm.Length < 8) Then
FileStrm.Close()
FileStrm.Dispose()
Return False
End If
'得到第一条索引的绝对偏移和最后一条索引的绝对偏移
FileStrm.Seek(0, SeekOrigin.Begin)
Index_Set = GetUInt32()
Index_End = GetUInt32()
'得到总索引条数
Index_Count = (Index_End - Index_Set) / 7 + 1
bFilePathInitialized = True
Return True
End Function
'主接口函数，根据传入的IP返回该IP的地址信息
Public Function GetAddressWithIP(ByVal IPvalue As String) As String
If Not bFilePathInitialized Then
Return ""
End If
Initialize()
'将IP转化为数字
Dim ip As UInt32 = IPToUInt32(IPvalue)
While (True)
'首先初始化本轮查找的区间
'区间头
Search_Set = IndexInfoAtPos(Search_Index_Set)
'区间尾
Search_End = IndexInfoAtPos(Search_Index_End)
'判断IP是否在区间头内
If (ip >= Search_Set.IpSet And ip <= Search_Set.IpEnd) Then
Return ReadAddressInfoAtOffset(Search_Set.Offset)
End If
'判断IP是否在区间尾内
If (ip >= Search_End.IpSet And ip <= Search_End.IpEnd) Then
Return ReadAddressInfoAtOffset(Search_End.Offset)
End If
'计算出区间中点
Search_Mid = IndexInfoAtPos((Search_Index_End + Search_Index_Set) / 2)
'判断IP是否在中点
If (ip >= Search_Mid.IpSet And ip <= Search_Mid.IpEnd) Then
Return ReadAddressInfoAtOffset(Search_Mid.Offset)
End If
'本轮没有找到，准备下一轮
If (ip < Search_Mid.IpSet) Then
'IP比区间中点要小，将区间尾设为现在的中点，将区间缩小1倍。
Search_Index_End = (Search_Index_End + Search_Index_Set) / 2
Else
'IP比区间中点要大，将区间头设为现在的中点，将区间缩小1倍。
Search_Index_Set = (Search_Index_End + Search_Index_Set) / 2
End If
End While
Return ""
End Function
'读取指定文件偏移位置的国家和地区信息
Protected Function ReadAddressInfoAtOffset(ByVal Offset As UInt32) As String
Dim country As String = ""
Dim area As String = ""
Dim country_Offset As UInt32 = 0
Dim Tag As Byte = 0
'跳过4字节，因这4个字节是该索引的IP区间上限。
FileStrm.Seek(Offset + 4, SeekOrigin.Begin)
'读取一个字节，得到描述国家信息的“寻址方式”
Tag = GetTag()
If (Tag = &H1) Then
'模式0x01，表示接下来的3个字节是表示偏移位置
FileStrm.Seek(GetOffset(), SeekOrigin.Begin)
'继续检查“寻址方式”
Tag = GetTag()
If (Tag = &H2) Then
'模式0x02，表示接下来的3个字节代表国家信息的偏移位置
'先将这个偏移位置保存起来，因为我们要读取它后面的地区信息。
country_Offset = GetOffset()
'读取地区信息（注：按照Luma的说明，好像没有这么多种可能性，但在测试过程中好像有些情况没有考虑到，
'所以写了个ReadArea()来读取。
area = ReadArea()
'读取国家信息
FileStrm.Seek(country_Offset, SeekOrigin.Begin)
country = ReadString()
Else
'这种模式说明接下来就是保存的国家和地区信息了，以'\0'代表结束。
FileStrm.Seek(-1, SeekOrigin.Current)
country = ReadString()
area = ReadArea()
End If
ElseIf (Tag = &H2) Then
'模式0x02，说明国家信息是一个偏移位置
country_Offset = GetOffset()
'先读取地区信息
area = ReadArea()
'读取国家信息
FileStrm.Seek(country_Offset, SeekOrigin.Begin)
country = ReadString()
Else
'这种模式最简单了，直接读取国家和地区就OK了
FileStrm.Seek(-1, SeekOrigin.Current)
country = ReadString()
area = ReadArea()
End If
Return country + " " + area
End Function
'从当前位置读取一个字符串（国家或者地区信息）
Protected Function ReadString() As String
Dim Offset As UInt32 = 0
Dim TempByteArray(256) As Byte
TempByteArray(Offset) = FileStrm.ReadByte()
While (TempByteArray(Offset) <> &H0)
Offset += 1
TempByteArray(Offset) = FileStrm.ReadByte()
End While
Return System.Text.Encoding.Default.GetString(TempByteArray)
End Function
'从当前文件位置读取地区信息
Protected Function ReadArea() As String
Dim Tag As Byte = GetTag()
If (Tag = &H1 Or Tag = &H2) Then
FileStrm.Seek(GetOffset(), SeekOrigin.Begin)
Return ReadString()
Else
FileStrm.Seek(-1, SeekOrigin.Current)
Return ReadString()
End If
End Function
'从当前文件位置读取一个字节的标识
Protected Function GetTag() As Byte
Return FileStrm.ReadByte()
End Function
'得到指定索引位置的信息（IP起始范围）
Protected Function IndexInfoAtPos(ByVal Index_Pos As Int32) As CZ_INDEX_INFO
Dim Index_Info As New CZ_INDEX_INFO
'根据索引编号计算出在文件中在偏移位置
FileStrm.Seek(Index_Set + 7 * Index_Pos, SeekOrigin.Begin)
Index_Info.IpSet = GetUInt32()
Index_Info.Offset = GetOffset()
FileStrm.Seek(Index_Info.Offset, SeekOrigin.Begin)
Index_Info.IpEnd = GetUInt32()
Return Index_Info
End Function
'读取3个字节，得到偏移位置
Protected Function GetOffset() As UInt32
Dim TempByte4(4) As Byte
TempByte4(0) = FileStrm.ReadByte()
TempByte4(1) = FileStrm.ReadByte()
TempByte4(2) = FileStrm.ReadByte()
TempByte4(3) = 0
Return BitConverter.ToUInt32(TempByte4, 0)
End Function
Protected Function GetUInt32() As UInt32
Dim TempByte4(4) As Byte
FileStrm.Read(TempByte4, 0, 4)
Return BitConverter.ToUInt32(TempByte4, 0)
End Function
'将字符串的IP转换成Int32
Public Shared Function IPToUInt32(ByVal Ipvalue As String) As UInt32
Dim IpByte() As String = Ipvalue.Split(".")
Dim nUpperBound As Int32 = IpByte.GetUpperBound(0)
If nUpperBound <> 3 Then
ReDim Preserve IpByte(4)
For i As Int32 = 1 To 3 - nUpperBound
IpByte(nUpperBound + i) = "0"
Next
End If
Dim TempByte4(4) As Byte
For i As Int32 = 0 To 3
'如果是.Net 2.0可以支持TryParse。
'If Not (Byte.TryParse(IpByte(i), TempByte4(3 - i))) Then
'TempByte4(3 - i) = &H0
'End If
If (IsNumeric(IpByte(i))) Then
TempByte4(3 - i) = CInt(IpByte(i)) And &HFF
End If
Next
Return BitConverter.ToUInt32(TempByte4, 0)
'System.Net.IPAddress.NetworkToHostOrder
End Function
'将Int32型的IP转换成字符串
Public Shared Function UInt32ToIP(ByVal UInt32value As UInt32) As String
Return New System.Net.IPAddress(System.Net.IPAddress.HostToNetworkOrder(UInt32value)).ToString()
End Function
End Class
