What am I doing wrong in calculating cidr IP range? - sql

Question

I am trying to write a function that will output some address information on a CIDR formatted IP (output underneath code):
create function dbo.ConvertIpToInt (#Ip as varchar(15))
returns bigint
as
begin
return (convert(bigint, parsename(#Ip, 1)) +
convert(bigint, parsename(#Ip, 2)) * 256 +
convert(bigint, parsename(#Ip, 3)) * 256 * 256 +
convert(bigint, parsename(#Ip, 4)) * 256 * 256 * 256)
end
go
create function dbo.ConvertIntToIp (#Int bigint)
returns varchar(15)
as
begin
declare
#IpHex varchar(8)
,#IpDotted varchar(15)
select
#IpHex = substring(convert(varchar(30), master.dbo.fn_varbintohexstr(#Int)), 11, 8)
select
#IpDotted = convert(varchar(3), convert(int, (convert(varbinary, substring(#IpHex, 1, 2), 2)))) + '.' +
convert(varchar(3), convert(int, (convert(varbinary, substring(#IpHex, 3, 2), 2)))) + '.' +
convert(varchar(3), convert(int, (convert(varbinary, substring(#IpHex, 5, 2), 2)))) + '.' +
convert(varchar(3), convert(int, (convert(varbinary, substring(#IpHex, 7, 2), 2))))
return #IpDotted
end
go
create function dbo.GetCidrIpRange (#CidrIp varchar(15))
returns #result table
(
CidrIp varchar(15) not null,
Mask int not null,
LowRange varchar(15) not null,
LowIp varchar(15) not null,
HighRange varchar(15) not null,
HighIp varchar(15) not null,
AddressQty bigint not null
)
as
begin
declare #Base bigint = cast(4294967295 as bigint)
declare #Mask int = cast(substring(#CidrIp, patindex('%/%' , #CidrIP) + 1, 2) as int)
declare #Power bigint = Power(2.0, 32.0 - #Mask) - 1
declare #LowRange bigint = dbo.ConvertIpToInt(left(#CidrIp, patindex('%/%' , #CidrIp) - 1)) & (#Base ^ #Power)
declare #HighRange bigint = #LowRange + #Power
insert #result
select
CidrIp = #CidrIp
, Mask = #Mask
, LowRange = #LowRange
, LowIp = dbo.ConvertIntToIp(#LowRange)
, HighRange = #HighRange
, HighIp = dbo.ConvertIntToIp(#HighRange)
, AddressQty = convert(bigint, power(2.0, (32.0 - #Mask)))
return
end
go
select * from dbo.GetCidrIpRange('195.65.254.11/2');
This outputs the following:
CidrIp Mask LowRange LowIp HighRange HighIp AddressQty
--------------------------------------------------------------------------------------
195.65.254.11/2 2 3221225472 192.0.0.0 4294967295 255.255.255.255 1073741824
I have been browsing SO and Google for some hours now, and I am quite convinced that ConvertIpToInt and ConvertIntToIp are correct.
However, I was expecting the following output:
CidrIp Mask LowRange LowIp HighRange HighIp AddressQty
--------------------------------------------------------------------------------------
195.65.254.11/2 2 3275881985 195.65.254.1 3275882238 195.65.254.254 254
Can someone please point me out where the mistake in my code is? I've been staring myself blind and I don't see it (or I am misunderstanding how to do this).

Answer 1

According to both http://www.ipaddressguide.com/cidr and http://jodies.de/ipcalc?host=195.65.254.11&mask1=2&mask2=, your calculations are correct. The only disagreement between those two sites is that the jodies.de/ipcalc page removes the lowest and highest (broadcast) IP addresses from the range.
I tested with both 195.65.254.11/2 and 195.65.254.11/24. In order to get your code working, I needed to change the input parameter specification on dbo.GetCidrIpRang to be VARCHAR(20) (as mentioned by #Damien_The_Unbeliever in a comment on the question).
Two notes regarding performance:
For the ConvertIpToInt and ConvertIntToIp Scalar UDFs you might be better off using the INET_AddressToNumber and INET_NumberToAddress functions, respectively, that are included in the Free version of the SQL# SQLCLR library (which I wrote, but hey, Free :). The reason for this recommendation is that unlike T-SQL UDFs, deterministic SQLCLR UDFs (and these two are) do not prevent parallel plans.
If you don't want to go the SQLCLR route, then you should, at the very least, keep the ConvertIntToIp function as purely mathematical. There is no reason to do all of those conversions and substrings.
CREATE FUNCTION dbo.IPNumberToAddress(#IPNumber BIGINT)
RETURNS VARCHAR(15)
WITH SCHEMABINDING
AS
BEGIN
DECLARE #Oct1 BIGINT,
#Oct2 INT,
#Oct3 INT;
SET #Oct1 = #IPNumber / (256 * 256 * 256);
SET #IPNumber -= (#Oct1 * (256 * 256 * 256));
SET #Oct2 = #IPNumber / (256 * 256);
SET #IPNumber -= (#Oct2 * (256 * 256));
SET #Oct3 = #IPNumber / 256;
SET #IPNumber -= (#Oct3 * 256);
RETURN CONCAT(#Oct1, '.', #Oct2, '.', #Oct3, '.', #IPNumber);
END;
GO
And then:
SELECT dbo.IPNumberToAddress(3275881995);
-- 195.65.254.11
For the GetCidrIpRange TVF, you would be better off converting that to be an Inline TVF. You can accomplish the multi-step calculations via CTEs in the following manner (you will just need to clean it up a little / finish it):
WITH cte1 AS
(
SELECT 2 AS [Mask] -- replace with real formula
), cte2 AS
(
SELECT 999 AS [Base], -- replace with real formula
POWER(2.0, 32.0 - cte1.[Mask]) - 1 AS [Power],
cte1.[Mask]
FROM cte1
), cte3 AS
(
SELECT SQL#.INET_AddressToNumber(left(#CidrIp, PATINDEX('%/%' , #CidrIp) - 1))
& (cte2.[Base] ^ cte2.[Power]) AS [LowRange],
cte2.[Power],
cte2.[Mask]
FROM cte2
)
SELECT #CidrIp AS [CidrIp],
cte3.[Mask],
cte3.[LowRange],
SQL#.INET_NumberToAddress(cte3.[LowRange]) AS [LowIp],
(cte3.[LowRange] + cte3.[Power]) AS [HighRange],
SQL#.INET_NumberToAddress(cte3.[LowRange] + cte3.[Power]) AS [HighIp],
CONVERT(BIGINT, POWER(2.0, (32.0 - cte3.[Mask]))) AS [AddressQty]
FROM cte3 c;