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IP to Integer

2010-2-2 7:22:00来源:Asp.net

有时候我们要判断某个IP是否在某个段内,如何实现呢? 一个简单办法就是把IP转换成Integer,然后判断整数是否在某个范围内就可以实现这个判断。

转换的算法如下:

比如我们要转换的IP为: 058.062.042.000

First Octet: 058
Second Octet: 062
Third Octet: 042
Fourth Octet: 000

计算公式如下:
(first octet * 2563) + (second octet * 2562) + (third octet * 256) + (fourth octet)
=  (first octet * 16777216) + (second octet * 65536) + (third octet * 256) + (fourth octet)
=  (058 * 16777216) + (062 * 65536) + (042 * 256) + (000)
=  977152512

网上有现成的服务,比如下面这个地址:

http://www.aboutmyip.com/AboutMyXApp/IP2Integer.jsp

SQL Server 的一个例子如下:

CREATE FUNCTION dbo.ipStringToInt 
( 
    @ip CHAR(15) 
) 
RETURNS INT 
AS 
BEGIN 
    DECLARE @rv INT, 
        @o1 INT, 
        @o2 INT, 
        @o3 INT, 
        @o4 INT, 
        @base INT 
 
    SELECT 
        @o1 = CONVERT(INT, PARSENAME(@ip, 4)), 
        @o2 = CONVERT(INT, PARSENAME(@ip, 3)), 
        @o3 = CONVERT(INT, PARSENAME(@ip, 2)), 
        @o4 = CONVERT(INT, PARSENAME(@ip, 1)) 
 
    IF (@o1 BETWEEN 0 AND 255) 
        AND (@o2 BETWEEN 0 AND 255) 
        AND (@o3 BETWEEN 0 AND 255) 
        AND (@o4 BETWEEN 0 AND 255) 
    BEGIN      
        SELECT @base = CASE 
            WHEN @o1 < 128 THEN 
                (@o1 * 16777216) 
            ELSE 
                -(256 - @o1) * 16777216 
            END 
     
        SET @rv = @base +  
            (@o2 * 65536) +  
            (@o3 * 256) + 
            (@o4) 
    END 
    ELSE 
        SET @rv = -1 
    RETURN @rv 
END
go

调用范例:

select dbo.ipStringToInt('058.062.042.000')

整数转换如下:

CREATE FUNCTION dbo.ipIntToString 
( 
    @ip INT 
) 
RETURNS CHAR(15) 
AS 
BEGIN 
    DECLARE @o1 INT, 
        @o2 INT, 
        @o3 INT, 
        @o4 INT 
 
    IF ABS(@ip) > 2147483647 
        RETURN '255.255.255.255' 
 
    SET @o1 = @ip / 16777216 
 
    IF @o1 = 0 
        SELECT @o1 = 255, @ip = @ip + 16777216 
 
    ELSE IF @o1 < 0 
    BEGIN 
        IF @ip % 16777216 = 0 
            SET @o1 = @o1 + 256 
        ELSE 
        BEGIN 
            SET @o1 = @o1 + 255 
            IF @o1 = 128 
                SET @ip = @ip + 2147483648 
            ELSE 
                SET @ip = @ip + (16777216 * (256 - @o1)) 
        END 
    END 
    ELSE 
    BEGIN 
        SET @ip = @ip - (16777216 * @o1) 
    END 
 
    SET @ip = @ip % 16777216 
    SET @o2 = @ip / 65536 
    SET @ip = @ip % 65536 
    SET @o3 = @ip / 256 
    SET @ip = @ip % 256 
    SET @o4 = @ip 
 
    RETURN 
        CONVERT(VARCHAR(4), @o1) + '.' + 
        CONVERT(VARCHAR(4), @o2) + '.' + 
        CONVERT(VARCHAR(4), @o3) + '.' + 
        CONVERT(VARCHAR(4), @o4) 
END
go

调用范例: