Porting from MySql to T-Sql. Any INET_ATON() equivalent?

Question

Need to move some code from MySql to TSql. I have a couple of calls to INET_ATON which converts a string which resembles an IPAddress into a number. Is there a T-SQL equivalent?

Answer 1

An abuse of the parsname function:

create function INET_ATON (@addr varchar(15))
returns bigint
with schemabinding
as
begin
  return  
    cast(parsename(@addr, 4) as bigint) * 16777216 +
    cast(parsename(@addr, 3) as bigint) * 65536 +
    cast(parsename(@addr, 2) as bigint) * 256 +
    cast(parsename(@addr, 1) as bigint)
end

That "short form address" thing is not supported here though.

Answer 2

Here's a function to convert an IP address to a string:

CREATE FUNCTION dbo.IpToString 
    (@ip_str VarChar(15))
returns BigInt
as
    begin
    declare @i int
    declare @dot_pos int
    declare @current_part VarChar(15)
    declare @result BigInt

    set @result = 0
    set @i = 0

    while Len(@ip_str) > 0
        begin
        set @i = @i + 1
        set @dot_pos = CharIndex('.', @ip_str)
        if @dot_pos > 0
            begin
            set @current_part = Left(@ip_str, @dot_pos - 1)
            set @ip_str = SubString(@ip_str, @dot_pos + 1, 15)
            end
        else 
            begin
            set @current_part = @ip_str
            set @ip_str = ''
            end

        if Len(@current_part) > 3 Return(Null)
        if IsNumeric(@current_part) = 0 Return (Null)
        if not cast(@current_part as int) between 0 and 255 Return (Null)
        set @result = 256 * @result + Cast(@current_part as BigInt)
        end

    if @i = 4 Return(@result)

    Return(Null)
    end

After creating the function, you can call it like:

select dbo.IpToString('1.2.3.4')

Answer 3

Little better. It uses int (4b) instead of bigint (8b). Your result should only be four bytes... one per octet:

create function INET_ATON (@ip varchar(15))
returns int
begin
    declare @rslt int 
    -- This first part is a little error checking
    -- Looks for three dots and all numbers when not dots 
    if len(@ip) - len(replace(@ip,'.','')) = 3 
        AND
            isnumeric(replace(@ip,'.','')) = 1
    begin 
    set @rslt = convert(int,
            convert(binary(1),convert(tinyint,parsename(@ip, 4)))
        +   convert(binary(1),convert(tinyint,parsename(@ip, 3)))
        +   convert(binary(1),convert(tinyint,parsename(@ip, 2)))
        +   convert(binary(1),convert(tinyint,parsename(@ip, 1)))
        )
    end
    else set @rslt = 0
    return @rslt
end;

Answer 4

More a different option than a direct answer to your question (I see the downvotes coming ^^), but you could also consider putting the conversion logic into your software instead of the query. Depending on language and use case this might be even better.

Examples

PHP: ip2long("192.168.1.1");

C/C++: inet_addr("192.168.1.1");

C#

System.Net.IPAddress ip;
long ipn = (System.Net.IPAddress.TryParse("192.168.1.1", out ip))

    ? (((long) ip.GetAddressBytes()[0] << 24) | (ip.GetAddressBytes()[1] << 16) |
              (ip.GetAddressBytes()[2] <<  8) |  ip.GetAddressBytes()[3])

    : 0;

You could also give it -1, or null (with long? as datatype), or write a method which throws an exception, in case the conversion fails.

Python

reduce(lambda sum, chunk: sum <<8 | chunk, map(int, '192.168.1.1'.split(".")))

Before you start downvoting: This is just a short example, no error handling here, I know.

Conclusion

Of course it is most of the time nicer to let the dbs do the job, but it really depends, and in case you don' t have a project with millions of requests per second, this might help.