Zones

$Id: zone,v 1.3 1999/03/03 12:20:05 marka Exp $

Overview

Zones are the unit of delegation in the DNS and may go from holding

RR's only at the zone top to holding the complete hierachy (private

roots zones). Zones are a container for the RRsets that make up the

zone.

Zone have certain properties associated with them.

* name

* class

* master / slave / stub / hint / cache / forward

* serial number

* signed / unsigned

* update periods (refresh / retry) (slave / stub)

* last update time (slave / stub)

* access restrictions

* transfer restrictions (master / slave)

* update restictions (master / slave)

* expire period (slave / stub)

* children => bottom

* glue

* rrsets / data

* transfer "in" in progress

* transfers "out" in progress

* "current" check in progress

* our masters

* primary master name (required to auto generate our masters)

* master file name

* database name

* transaction logs

* notification lists

* NS's

* static additional sites (stealth servers)

* dynamically leared sites (soa queries)

Zones have two types of versions associated with them.

Type 1.

The image of the "current" zone when a AXFR out is in progress.

There may be several of these at once but they cease to need

to exist once the AXFR's on this version has completed.

Type 2.

These are virtual versions of the zone and are required to

support IXFR requests. While the entire contents of the old

version does not need to be kept, a change log needs to be

kept. An index into this log would be useful in speeding

up replies. These versions have an explict expiry date.

"How long are we going to keep them operationally?"

While there are expriry dates based on last update /

change time + expire. In practice holding the deltas

for a few refresh periods should be enough. If the network

and servers are up one is enough.

"How are we going to generate them from a master file?"

UPDATE should not be the only answer to this question.

We need a tool that takes the current zone & new zone.

Verifies the new zone, generates a delta and feeds this

at named. It could well be part of ndc but does not have

to be.

Zones need to have certain operations performed on them. The need to

be:

* loaded

* unloaded

* dumped

* updated (UPDATE / IXFR)

* copied out in full (AXFR) or as partial deltas (IXFR)

* read from

* validated

* generate a delta between two given versions.

* signed / resigned

* maintaince

validate current soa

remove old deltas / consolidation

purge stale rrsets (cache)

* notification

responding to

generating

Types:

typedef enum {

dns_zone_none = 0,

dns_zone_master,

dns_zone_slave,

dns_zone_stub,

dns_zone_hint,

dns_zone_cache,

dns_zone_forward

} dns_zonetypes_t;

typedef struct dns_ixfr dns_ixfr_t;

struct dns_ixfr {

unsigned int magic; /*IXFR*/

isc_uint32_t serial;

time_t expire;

unsigned int offset;

ISC_LINK(dns_ixfr_t) link;

};

struct dns_zone {

unsigned int magic; /* ZONE */

dns_name_t name;

dns_rdataclass_t class;

dns_zonetypes_t type;

dns_rbt_t top;

isc_uint32_t version;

isc_uint32_t serial;

isc_uint32_t refresh;

isc_uint32_t retry;

isc_uint32_t serial;

char *masterfile;

dns_acl_t *access;

dns_acl_t *transfer;

struct {

dns_acl_t *acl;

dns_scl_t *scl; /* tsig based acl */

} update;

char *database;

ISC_LIST(dns_ixfr_t) ixfr;

...

};

Operations:

Loading:

Functions:

void

dns_zone_init(dns_zone_t * zone, dns_rdataclass_t class,

isc_mem_t *mxtc);

void

dns_zone_invalidate(dns_zone_t *zone);

void

dns_ixfr_init(dns_ixfr_t *ixfr, unsigned long serial, time_t expire);

void

dns_ixfr_invalidate(dns_ixfr_t *ixfr);

dns_zone_axfrout(dns_zone_t *zone);