[Freeipa-devel] [PATCH 0063] Notify DNS slaves if zone serial number modification was detected.

[Petr Spacek]

On 09/24/2012 03:09 PM, Adam Tkac wrote:
> On Mon, Sep 17, 2012 at 02:55:06PM +0200, Petr Spacek wrote:
>> Hello,
>>
>> this patch adds missing notification to DNS slaves if zone serial
>> number modification was detected.
>
> Hi,
>
> please check my comment below.
>
>>  From eb8d7fc0c02e03b9c7c90e497225536c449fab1c Mon Sep 17 00:00:00 2001
>> From: Petr Spacek <pspacek at redhat.com>
>> Date: Mon, 17 Sep 2012 14:29:45 +0200
>> Subject: [PATCH] Notify DNS slaves if zone serial number modification was
>>   detected.
>>
>> Signed-off-by: Petr Spacek <pspacek at redhat.com>
>> ---
>>   src/ldap_helper.c | 22 ++++++++++++++--------
>>   1 file changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/src/ldap_helper.c b/src/ldap_helper.c
>> index 658b960f50b461fa602edf51e955f3bdd4769e1d..d22e8714df57edaad4cf45e6cc26ec0dbbd59108 100644
>> --- a/src/ldap_helper.c
>> +++ b/src/ldap_helper.c
>> @@ -1035,9 +1035,10 @@ ldap_parse_zoneentry(ldap_entry_t *entry, ldap_instance_t *inst)
>>   	isc_task_t *task = inst->task;
>>   	isc_uint32_t ldap_serial;
>>   	isc_uint32_t zr_serial;	/* SOA serial value from in-memory zone register */
>> -	unsigned char ldap_digest[RDLIST_DIGESTLENGTH];
>> +	unsigned char ldap_digest[RDLIST_DIGESTLENGTH] = {0};
>>   	unsigned char *zr_digest = NULL;
>>   	ldapdb_rdatalist_t rdatalist;
>> +	isc_boolean_t zone_dynamic = ISC_FALSE;
>>
>>   	REQUIRE(entry != NULL);
>>   	REQUIRE(inst != NULL);
>> @@ -1131,13 +1132,13 @@ ldap_parse_zoneentry(ldap_entry_t *entry, ldap_instance_t *inst)
>>   		&& result != DNS_R_DYNAMIC && result != DNS_R_CONTINUE)
>>   		goto cleanup;
>>
>> +	zone_dynamic = (result == DNS_R_DYNAMIC);
>>   	result = ISC_R_SUCCESS;
>>
>>   	/* initialize serial in zone register and always increment serial
>>   	 * for a new zone (typically after BIND start)
>>   	 * - the zone was possibly changed in meanwhile */
>>   	if (publish) {
>> -		memset(ldap_digest, 0, RDLIST_DIGESTLENGTH);
>>   		CHECK(ldap_get_zone_serial(inst, &name, &ldap_serial));
>>   		CHECK(zr_set_zone_serial_digest(inst->zone_register, &name, ldap_serial,
>>   				ldap_digest));
>> @@ -1154,23 +1155,28 @@ ldap_parse_zoneentry(ldap_entry_t *entry, ldap_instance_t *inst)
>>   	 * 3c) The old and new serials are same: autoincrement only if something
>>   	 *     else was changed.
>>   	 */
>> +	CHECK(ldap_get_zone_serial(inst, &name, &ldap_serial));
>> +	CHECK(zr_get_zone_serial_digest(inst->zone_register, &name, &zr_serial,
>> +			&zr_digest));
>>   	if (inst->serial_autoincrement) {
>> -		CHECK(ldap_get_zone_serial(inst, &name, &ldap_serial));
>>   		CHECK(ldapdb_rdatalist_get(inst->mctx, inst, &name,
>>   				&name, &rdatalist));
>>   		CHECK(rdatalist_digest(inst->mctx, &rdatalist, ldap_digest));
>>
>> -		CHECK(zr_get_zone_serial_digest(inst->zone_register, &name, &zr_serial,
>> -				&zr_digest));
>>   		if (ldap_serial == zr_serial) {
>>   			/* serials are same - increment only if something was changed */
>>   			if (memcmp(zr_digest, ldap_digest, RDLIST_DIGESTLENGTH) != 0)
>>   				CHECK(soa_serial_increment(inst->mctx, inst, &name));
>> -		} else { /* serial in LDAP was changed - update zone register */
>> -			CHECK(zr_set_zone_serial_digest(inst->zone_register, &name,
>> -					ldap_serial, ldap_digest));
>>   		}
>>   	}
>> +	if (ldap_serial != zr_serial) {
>> +		/* serial in LDAP was changed - update zone register */
>> +		CHECK(zr_set_zone_serial_digest(inst->zone_register, &name,
>> +				ldap_serial, ldap_digest));
>> +
>> +		if (zone_dynamic)
>> +			dns_zone_notify(zone);
>
> This if() doesn't seem fully correct to me. Although in most FreeIPA scenarios
> it will work, consider situation when someone disables DDNS updates for zone and
> modifies records in LDAP. In this case zone_dynamic is FALSE but SOA serial
> changes.
>
> I would recommend to simpy send notify every time when serial changes.

Two lines above start of the patch is following code:

result = dns_zone_load(zone);
	if (result != ISC_R_SUCCESS && result != DNS_R_UPTODATE
		&& result != DNS_R_DYNAMIC && result != DNS_R_CONTINUE)
		goto cleanup;

	zone_dynamic = (result == DNS_R_DYNAMIC);

For non-dynamic zones "dns_zone_load()" sends notifies. Zone_dynamic condition 
only prevents doubled dns_zone_notify() calls for non-dynamic zones. I can 
remove this condition if doubled calls are not problem.

Petr^2 Spacek

>
> Regards, Adam
>
>> +	}
>>
>>   cleanup:
>>   	if (unlock)
>> --
>> 1.7.11.4
>>
>
>