update.c

/* update.c
 *
 * Functions for RFC 2136 Dynamic Update
 *
 * Copyright (c) 2005-2008, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
 */

#include <ldns/config.h>

#include <ldns/ldns.h>

#include <strings.h>
#include <stdlib.h>
#include <limits.h>

/*
 * RFC 2136 sections mapped to RFC 1035:
 *              zone/ZO -- QD/question
 *     prerequisites/PR -- AN/answers
 *           updates/UP -- NS/authority records
 *   additional data/AD -- AR/additional records
 */

ldns_pkt *
ldns_update_pkt_new(ldns_rdf *zone_rdf, ldns_rr_class c,
    const ldns_rr_list *pr_rrlist, const ldns_rr_list *up_rrlist, const ldns_rr_list *ad_rrlist)
{
	ldns_pkt *p;

	if (!zone_rdf || !up_rrlist) {
		return NULL;
	}

	if (c == 0) { 
		c = LDNS_RR_CLASS_IN;
	}

	/* Create packet, fill in Zone Section. */
	p = ldns_pkt_query_new(zone_rdf, LDNS_RR_TYPE_SOA, c, LDNS_RD);
	if (!p) {
		return NULL;
	}
	zone_rdf = NULL; /* No longer safe to use. */

	ldns_pkt_set_opcode(p, LDNS_PACKET_UPDATE);

	ldns_rr_list_deep_free(p->_authority);

	ldns_pkt_set_authority(p, ldns_rr_list_clone(up_rrlist));

	ldns_update_set_upcount(p, ldns_rr_list_rr_count(up_rrlist));

	if (pr_rrlist) {
		ldns_rr_list_deep_free(p->_answer); /*XXX access function */
		ldns_pkt_set_answer(p, ldns_rr_list_clone(pr_rrlist));
		ldns_update_set_prcount(p, ldns_rr_list_rr_count(pr_rrlist));
	}

	if (ad_rrlist) {
		ldns_rr_list_deep_free(p->_additional);
		ldns_pkt_set_additional(p, ldns_rr_list_clone(ad_rrlist));
		ldns_update_set_adcount(p, ldns_rr_list_rr_count(ad_rrlist));
	}
	return p;
}

ldns_status
ldns_update_pkt_tsig_add(ldns_pkt *p, const ldns_resolver *r)
{
#ifdef HAVE_SSL
	uint16_t fudge = 300; /* Recommended fudge. [RFC2845 6.4]  */
	if (ldns_resolver_tsig_keyname(r) && ldns_resolver_tsig_keydata(r))
		return ldns_pkt_tsig_sign(p, ldns_resolver_tsig_keyname(r),
		    ldns_resolver_tsig_keydata(r), fudge,
		    ldns_resolver_tsig_algorithm(r), NULL);
#else
	/* do nothing */
	(void)p;
	(void)r;
#endif /* HAVE_SSL */
	/* No TSIG to do. */
	return LDNS_STATUS_OK;
}

/* Move to higher.c or similar? */
/* XXX doc */
ldns_status
ldns_update_soa_mname(ldns_rdf *zone, ldns_resolver *r,
    ldns_rr_class c, ldns_rdf **mname)
{
	ldns_rr		*soa_rr;
	ldns_pkt	*query, *resp;

	/* Nondestructive, so clone 'zone' here */
	query = ldns_pkt_query_new(ldns_rdf_clone(zone), LDNS_RR_TYPE_SOA,
	    c, LDNS_RD);
	if (!query) {
		return LDNS_STATUS_ERR;
	}

	ldns_pkt_set_random_id(query);
	if (ldns_resolver_send_pkt(&resp, r, query) != LDNS_STATUS_OK) {
		ldns_pkt_free(query);
		return LDNS_STATUS_ERR;
	}
	ldns_pkt_free(query);
	if (!resp) {
		return LDNS_STATUS_ERR;
	}

	/* Expect a SOA answer. */
	*mname = NULL;
	while ((soa_rr = ldns_rr_list_pop_rr(ldns_pkt_answer(resp)))) {
		if (ldns_rr_get_type(soa_rr) != LDNS_RR_TYPE_SOA
				|| ldns_rr_rdf(soa_rr, 0) == NULL)
			continue;
		/* [RFC1035 3.3.13] */
		*mname = ldns_rdf_clone(ldns_rr_rdf(soa_rr, 0));
		break;
	}
	ldns_pkt_free(resp);

	return *mname ? LDNS_STATUS_OK : LDNS_STATUS_ERR;
}

/* Try to get zone and MNAME from SOA queries. */
ldns_status
ldns_update_soa_zone_mname(const char *fqdn, ldns_resolver *r,
    ldns_rr_class c, ldns_rdf **zone_rdf, ldns_rdf **mname_rdf)
{
	ldns_rr		*soa_rr, *rr;
	ldns_rdf	*soa_zone = NULL, *soa_mname = NULL;
	ldns_rdf	*ipaddr, *fqdn_rdf, *tmp;
	ldns_rdf	**nslist;
	ldns_pkt	*query, *resp;
	ldns_resolver   *tmp_r;
	size_t		i;

	/* 
	 * XXX Ok, this cannot be the best way to find this...?
	 * XXX (I run into weird cache-related stuff here)
	 */

	/* Step 1 - first find a nameserver that should know *something* */
	fqdn_rdf = ldns_dname_new_frm_str(fqdn);
	query = ldns_pkt_query_new(fqdn_rdf, LDNS_RR_TYPE_SOA, c, LDNS_RD);
	if (!query) {
		return LDNS_STATUS_ERR;
	}
	fqdn_rdf = NULL;

	ldns_pkt_set_random_id(query);
	if (ldns_resolver_send_pkt(&resp, r, query) != LDNS_STATUS_OK) {
		ldns_pkt_free(query);
		return LDNS_STATUS_ERR;
	}
	ldns_pkt_free(query);
	if (!resp) {
		return LDNS_STATUS_ERR;
	}

	/* XXX Is it safe to only look in authority section here? */
	while ((soa_rr = ldns_rr_list_pop_rr(ldns_pkt_authority(resp)))) {
		if (ldns_rr_get_type(soa_rr) != LDNS_RR_TYPE_SOA
				|| ldns_rr_rdf(soa_rr, 0) == NULL)
			continue;
		/* [RFC1035 3.3.13] */
		soa_mname = ldns_rdf_clone(ldns_rr_rdf(soa_rr, 0));
		break;
	}
	ldns_pkt_free(resp);
	if (!soa_rr) {
		return LDNS_STATUS_ERR;
	}

	/* Step 2 - find SOA MNAME IP address, add to resolver */
	query = ldns_pkt_query_new(soa_mname, LDNS_RR_TYPE_A, c, LDNS_RD);
	if (!query) {
		return LDNS_STATUS_ERR;
	}
	soa_mname = NULL;

	ldns_pkt_set_random_id(query);
	if (ldns_resolver_send_pkt(&resp, r, query) != LDNS_STATUS_OK) {
		ldns_pkt_free(query);
		return LDNS_STATUS_ERR;
	}
	ldns_pkt_free(query);
	if (!resp) {
		return LDNS_STATUS_ERR;
	}

	if (ldns_pkt_ancount(resp) == 0) {
		ldns_pkt_free(resp);
		return LDNS_STATUS_ERR;
	}

	/* XXX There may be more than one answer RR here. */
	rr = ldns_rr_list_pop_rr(ldns_pkt_answer(resp));
	ipaddr = ldns_rr_rdf(rr, 0);

	/* Put the SOA mname IP first in the nameserver list. */
	if (!(tmp_r = ldns_resolver_clone(r))) {
		return LDNS_STATUS_MEM_ERR;
	}
	nslist = ldns_resolver_nameservers(tmp_r);
	for (i = 0; i < ldns_resolver_nameserver_count(tmp_r); i++) {
		if (ldns_rdf_compare(ipaddr, nslist[i]) == 0) {
			if (i) {
				tmp = nslist[0];
				nslist[0] = nslist[i];
				nslist[i] = tmp;
			}
			break;
		}
	}
	if (i >= ldns_resolver_nameserver_count(tmp_r)) {
		/* SOA mname was not part of the resolver so add it first. */
		(void) ldns_resolver_push_nameserver(tmp_r, ipaddr);
		nslist = ldns_resolver_nameservers(tmp_r);
		i = ldns_resolver_nameserver_count(tmp_r) - 1;
		tmp = nslist[0];
		nslist[0] = nslist[i];
		nslist[i] = tmp;
	}
	ldns_pkt_free(resp);

	/* Make sure to ask the first in the list, i.e SOA mname */
	ldns_resolver_set_random(tmp_r, false);

	/* Step 3 - Redo SOA query, sending to SOA MNAME directly. */
	fqdn_rdf = ldns_dname_new_frm_str(fqdn);
	query = ldns_pkt_query_new(fqdn_rdf, LDNS_RR_TYPE_SOA, c, LDNS_RD);
	if (!query) {
		ldns_resolver_free(tmp_r);
		return LDNS_STATUS_ERR;
	}
	fqdn_rdf = NULL;

	ldns_pkt_set_random_id(query);
	if (ldns_resolver_send_pkt(&resp, tmp_r, query) != LDNS_STATUS_OK) {
		ldns_pkt_free(query);
		ldns_resolver_free(tmp_r);
		return LDNS_STATUS_ERR;
	}
	ldns_resolver_free(tmp_r);
	ldns_pkt_free(query);
	if (!resp) {
		return LDNS_STATUS_ERR;
	}

	/* XXX Is it safe to only look in authority section here, too? */
	while ((soa_rr = ldns_rr_list_pop_rr(ldns_pkt_authority(resp)))) {
		if (ldns_rr_get_type(soa_rr) != LDNS_RR_TYPE_SOA
				|| ldns_rr_rdf(soa_rr, 0) == NULL)
			continue;
		/* [RFC1035 3.3.13] */
		soa_mname = ldns_rdf_clone(ldns_rr_rdf(soa_rr, 0));
		soa_zone = ldns_rdf_clone(ldns_rr_owner(soa_rr));
		break;
	}
	ldns_pkt_free(resp);
	if (!soa_rr) {
		return LDNS_STATUS_ERR;
	}

	/* That seems to have worked, pass results to caller. */
	*zone_rdf = soa_zone;
	*mname_rdf = soa_mname;
	return LDNS_STATUS_OK;
}	

/*
 * ldns_update_{get,set}_{zo,pr,up,ad}count
 */

uint16_t
ldns_update_zocount(const ldns_pkt *p)
{
	return ldns_pkt_qdcount(p);
}

uint16_t
ldns_update_prcount(const ldns_pkt *p)
{
	return ldns_pkt_ancount(p);
}

uint16_t
ldns_update_upcount(const ldns_pkt *p)
{
	return ldns_pkt_nscount(p);
}

uint16_t
ldns_update_ad(const ldns_pkt *p)
{
	return ldns_pkt_arcount(p);
}

void
ldns_update_set_zo(ldns_pkt *p, uint16_t v)
{
	ldns_pkt_set_qdcount(p, v);
}

void
ldns_update_set_prcount(ldns_pkt *p, uint16_t v)
{
	ldns_pkt_set_ancount(p, v);
}

void
ldns_update_set_upcount(ldns_pkt *p, uint16_t v)
{
	ldns_pkt_set_nscount(p, v);
}

void
ldns_update_set_adcount(ldns_pkt *p, uint16_t v)
{
	ldns_pkt_set_arcount(p, v);
}