inet increment w/ int8

oops

- FUNCTION inet_inc(int, int8) RETURNS inet
+ FUNCTION inet_inc(inet, int8) RETURNS inet

Would you modify this so it can go in /contrib or pgfoundry? Is there
general interest for this?

---------------------------------------------------------------------------

Ilya A. Kovalenko wrote:

Greetings,

I suggest function for "inet" increment w/ int8 (signed).

FUNCTION inet_inc(int, int8) RETURNS inet

Function, useful for making address pools (using also
existing "inet" compare functions to trap boundaries).

Notes:
This version lets address wrap around 0-*ff boundary.
Uses couple of non-POSIX functions - betoh64() and htobe64()
Tested on i386 with OpenBSD 3.7
PostgreSQL 8.0.2

-----------------------------------------------------
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "postgres.h" /* general Postgres declarations */

#include "fmgr.h" /* for argument/result macros */
#include "utils/inet.h"

Datum inet_inc(PG_FUNCTION_ARGS);

//------ stolen from backend/utils/adt/network.c --------

#define ip_family(inetptr) \
(((inet_struct *)VARDATA(inetptr))->family)
#define ip_bits(inetptr) \
(((inet_struct *)VARDATA(inetptr))->bits)
#define ip_type(inetptr) \
(((inet_struct *)VARDATA(inetptr))->type)
#define ip_addr(inetptr) \
(((inet_struct *)VARDATA(inetptr))->ipaddr)
#define ip_maxbits(inetptr) \
(ip_family(inetptr) == PGSQL_AF_INET ? 32 : 128)

static int
ip_addrsize(inet *inetptr)
{
switch (ip_family(inetptr))
{
case PGSQL_AF_INET:
return 4;
case PGSQL_AF_INET6:
return 16;
default:
return 0;
}
}
//-------------------------------------------------------

PG_FUNCTION_INFO_V1(inet_inc);

Datum
inet_inc(PG_FUNCTION_ARGS)
{
inet *src = PG_GETARG_INET_P(0);
int64 arg = PG_GETARG_INT64(1);
inet *dst;
uint64 wsp;

// allocate destination structure
dst = (inet *) palloc0(VARHDRSZ + sizeof(inet_struct));

// copy to destination
*((inet_struct *)VARDATA(dst)) = *((inet_struct *)VARDATA(src));

if (ip_family(dst) == PGSQL_AF_INET)
{
// Increment v4 address w/ item truncated to 32 bits
*((uint32*)(ip_addr(dst))) =
htonl(ntohl(*((int32*)(ip_addr(dst)))) + (int32)arg);
}
else
{
// Increment v6 address low qword (store to workspace)
wsp = htobe64(betoh64(*((int64*)(ip_addr(dst) + 8))) + arg);
*((uint64*)(ip_addr(dst) + 8)) = wsp;

// Carry/borrow high qword
if ( arg > 0 && wsp < *((uint64*)(ip_addr(src) + 8)) )
{ *((int64*)(ip_addr(dst))) =
htobe64(betoh64(*((int64*)(ip_addr(dst)))) + 1);
}
else
if ( arg < 0 && wsp > *((uint64*)(ip_addr(src) + 8)) )
{ *((int64*)(ip_addr(dst))) =
htobe64(betoh64(*((int64*)(ip_addr(dst)))) - 1);
}
}

// Return result
VARATT_SIZEP(dst) = VARHDRSZ
+ ((char *) ip_addr(dst) - (char *) VARDATA(dst))
+ ip_addrsize(dst);

PG_RETURN_INET_P(dst);

}
-----------------------------------------------------

Thank you

Ilya A. Kovalenko (mailto:shadow@oganer.net)
SpecialEQ SW section
JSC Oganer-Service

P.S. Treat as Public Domain

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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

On Mon, Apr 18, 2005 at 08:58:01PM -0400, Bruce Momjian wrote:

Would you modify this so it can go in /contrib or pgfoundry? Is there
general interest for this?

I was about to sit down and write the same function yesterday, when as if
by magic this appeared. In my case it is to loop over ip numbers in a
class C looking for a free one to allocate. So, from here there is
interest..

Cheers,

Patrick

BM> Would you modify this so it can go in /contrib or pgfoundry? Is there
BM> general interest for this?

Actually, I suggested to do such or similar function as internal.
PostgreSQL has inet/cidr - excellent data type and good facilities to
examine and compare inet values, but has no facilities to modify
them (i.e. get-change-return operations).

There is place for many useful operators and functions to do but
they not invented enough yet (to supplement with existing facilites
and each other).

Only facility that has no doubt is increment/decrement inet
address value with numeric value. It nicely supplements existing
inet compare operators (that compares two addresses as numeric
values). Also, it can be used to override "+" and "-" operators
between inet and numeric values.

I understand, that you have more important things to do, so I write
this function, to save your time.

Maybe, it is good idea, to implement such functions separatelly as
/contrib ... for a start ...

Live example for inet_inc() (as "+" operator)

(PL/pgSQL)

-- (try to) Peek address from group pool
SELECT next INTO next_ip FROM peer_ranges WHERE
group_id = (SELECT id FROM peer_groups WHERE name = $3) AND
next < last
ORDER BY first LIMIT 1;

-- Return NULL if pool is empty
IF NOT FOUND THEN
RAISE NOTICE ''Group address pool is empty'';
RETURN NULL;
END IF;

-- Update pool
UPDATE peer_ranges SET next = next_ip + 1 WHERE next = next_ip;

RETURN next_ip;

where, peer_ranges is:

CREATE TABLE peer_ranges
( group_id bigint NOT NULL REFERENCES peer_groups (id),
first inet NOT NULL UNIQUE,
next inet NOT NULL UNIQUE,
last inet NOT NULL UNIQUE
);

Thank you,

Ilya A. Kovalenko (mailto:shadow@oganer.net)

Ilya A. Kovalenko wrote:

BM> Would you modify this so it can go in /contrib or pgfoundry? Is there
BM> general interest for this?

Actually, I suggested to do such or similar function as internal.
PostgreSQL has inet/cidr - excellent data type and good facilities to
examine and compare inet values, but has no facilities to modify
them (i.e. get-change-return operations).

There is place for many useful operators and functions to do but
they not invented enough yet (to supplement with existing facilites
and each other).

Only facility that has no doubt is increment/decrement inet
address value with numeric value. It nicely supplements existing
inet compare operators (that compares two addresses as numeric
values). Also, it can be used to override "+" and "-" operators
between inet and numeric values.

I understand, that you have more important things to do, so I write
this function, to save your time.

Agreed. Let's implement '+/-' for 'inet + int4' and put it in the
backend as standard (I can help do the system table stuff if you give me
the C functions). However, how do we handle cases where int4 > 255. I
am thinking we should support only inet + inet, like this:

SELECT '1.2.3.4'::inet + '0.0.1.2'::inet;

But how do we do:

SELECT '1.2.3.255'::inet + '0.0.0.1'::inet;

I assume this becomes '1.2.4.0'. Inet +/- inet seems the most flexible
because it allows you to add to any part of the mask, rather than just
the lower-order bytes, or trying to make sense that 256 adds like
'0.0.1.0'.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

am thinking we should support only inet + inet, like this:

SELECT '1.2.3.4'::inet + '0.0.1.2'::inet;

I don't think inet+inet makes any sense.

I think inet+int4 should work by adding to the host address and overflowing if
it exceeds the network mask.

Ie,

10.0.0.0/24 + 1 = 10.0.0.1/24
10.0.0.255/24 + 1 => overflow

Or

10.1/16 + 1 = 10.1.0.1/16
10.1/16 + 16384 = 10.1.64.0/16
10.1/16 + 65536 => overflow

--
greg

Greg Stark wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

am thinking we should support only inet + inet, like this:

SELECT '1.2.3.4'::inet + '0.0.1.2'::inet;

I don't think inet+inet makes any sense.

I think inet+int4 should work by adding to the host address and overflowing if
it exceeds the network mask.

Ie,

10.0.0.0/24 + 1 = 10.0.0.1/24
10.0.0.255/24 + 1 => overflow

Or

10.1/16 + 1 = 10.1.0.1/16
10.1/16 + 16384 = 10.1.64.0/16
10.1/16 + 65536 => overflow

So, do not overflow? We can do that. Another idea Tom had was creating
a function that increments/decrements the address or the network portion
of the address, and if you increment past the non-network portion that
overflows too.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Ie,

10.0.0.0/24 + 1 = 10.0.0.1/24
10.0.0.255/24 + 1 => overflow

Or

10.1/16 + 1 = 10.1.0.1/16
10.1/16 + 16384 = 10.1.64.0/16
10.1/16 + 65536 => overflow

So, do not overflow?

You mean not doing modulus arithemtic? Yes. Overflow instead.

I see a use case for of generating addresses based on a sequence or some
primary key from the database.

Something like

CREATE SEQUENCE hosts_ip_seq MAXVALUE 65536;
ALTER TABLE hosts ALTER ip SET DEFAULT '10.0.0.0/16'::inet + nextval(hosts_ip_seq')

Using the primary key or some foreign key in the table would require a trigger
which would take too much work to cons up an example for.

--
greg

On Tue, Apr 19, 2005 at 12:03:27 -0400,
Bruce Momjian <pgman@candle.pha.pa.us> wrote:

Agreed. Let's implement '+/-' for 'inet + int4' and put it in the
backend as standard (I can help do the system table stuff if you give me
the C functions). However, how do we handle cases where int4 > 255. I
am thinking we should support only inet + inet, like this:

SELECT '1.2.3.4'::inet + '0.0.1.2'::inet;

I don't think this operation makes much sense. Adding an integer makes
some sense, but I think the original problem would be better solved
by having a set returning function generate the possible network addresses
to be allocated and store that set in a table.

I don't think assuming everthing is a /24 is a good idea. If wrapping is
to be done, there should be some mask specified.

BM> Greg Stark wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

am thinking we should support only inet + inet, like this:

SELECT '1.2.3.4'::inet + '0.0.1.2'::inet;

I don't think inet+inet makes any sense.

I think inet+int4 should work by adding to the host address and overflowing if
it exceeds the network mask.

Ie,

10.0.0.0/24 + 1 = 10.0.0.1/24
10.0.0.255/24 + 1 => overflow

Or

10.1/16 + 1 = 10.1.0.1/16
10.1/16 + 16384 = 10.1.64.0/16
10.1/16 + 65536 => overflow

BM> So, do not overflow? We can do that. Another idea Tom had was creating
BM> a function that increments/decrements the address or the network portion
BM> of the address, and if you increment past the non-network portion that
BM> overflows too.

Hmm, actually, you can do several functions to increase/decrease
network address with different overflow models (octet-overflow,
host part overflow, full address overflow, or without overflow
as special case), for flexibility.
Another question, what model choose for '+/-' ...

BTW, why 'inet + int4' (not int8), what about v6 ?

Few words for 'inet + inet'. It's can be useful for IPv6 addresses
(because you don't have 128-bit numeric type, except, maybe, 'numeric'
one).
But, there is another way to reach higher octets - use existing
inet_{send|receive} functions.

<disclaimer text='raw ideas and thoughts'>

Or invent something new like this:

-- <src> <index> <value>
FUNCTION extract_octet(inet, integer) RETURNS integer
FUNCTION extract_word (inet, integer) RETURNS int2
FUNCTION extract_dword(inet, integer) RETURNS int4
FUNCTION extract_qword(inet, integer) RETURNS int8

-- <src> <index> <value>
FUNCTION replace_octet(inet, integer, integer) RETURNS inet
FUNCTION replace_word (inet, integer, int2) RETURNS inet
FUNCTION replace_dword(inet, integer, int4) RETURNS inet
FUNCTION replace_qword(inet, integer, int8) RETURNS inet

(not established with signed 'int%')

</disclaimer>

Ilya A. Kovalenko

GS> I see a use case for of generating addresses based on a sequence or some
GS> primary key from the database.

GS> Something like

GS> CREATE SEQUENCE hosts_ip_seq MAXVALUE 65536;
GS> ALTER TABLE hosts ALTER ip SET DEFAULT '10.0.0.0/16'::inet + nextval(hosts_ip_seq')

hmm, not quite good idea - SEQUENCEs, by design, does not rollback next
value on transation rollback, so you'll have holes on address range when
other values will break some constraints or concurrent sessions
appears.

On Wed, Apr 20, 2005 at 12:30:08 +0800,
"Ilya A. Kovalenko" <shadow@oganer.net> wrote:

GS> I see a use case for of generating addresses based on a sequence or some
GS> primary key from the database.

GS> Something like

GS> CREATE SEQUENCE hosts_ip_seq MAXVALUE 65536;
GS> ALTER TABLE hosts ALTER ip SET DEFAULT '10.0.0.0/16'::inet + nextval(hosts_ip_seq')

hmm, not quite good idea - SEQUENCEs, by design, does not rollback next
value on transation rollback, so you'll have holes on address range when
other values will break some constraints or concurrent sessions
appears.

You are going to have to have some way of handling holes anyway. What
happens when an allocated IP address is returned? That is why I think
for most uses a table with a row for each possible allocation is the
way to go.