resolve.c

此dns服务器是在mydns基础上改写

	return (rv);
}
/*--- process_rr() ------------------------------------------------------------------------------*/


/**************************************************************************************************
	ADD_AUTHORITY_NS
	Adds AUTHORITY records for any NS records that match the request.
**************************************************************************************************/
static inline void
add_authority_ns(TASK *t, datasection_t section, MYDNS_SOA *soa, char *match_label)
{
	if (!t->ns.size && section == ANSWER)
	{
		register MYDNS_RR *rr = NULL, *r = NULL;
		register char *label = NULL;

#if DEBUG_ENABLED && DEBUG_RESOLVE
		Debug("%s: add_authority_ns(%s, (%s), \"%s\")",
				desctask(t), resolve_datasection_str[section], soa->origin, match_label);
#endif
		/* Match down label by label in `label' -- include first matching NS record(s) */
		for (label = match_label; *label; label++)
		{
			if (label == match_label || *label == '.')
			{
				if (label[0] == '.' && label[1]) label++;		/* Advance past leading dot */

				/* Ignore NS records on wildcard (is that correct behavior?) */
				if (*label != '*')
				{
#if DEBUG_ENABLED && DEBUG_RESOLVE
					Debug("%s: Checking for NS (AUTHORITY) for label \"%s\" (would be glue)",
							desctask(t), label);
#endif
					if ((rr = find_rr(t, soa, DNS_QTYPE_NS, label)))
					{
						for (r = rr; r; r = r->next)
						{
							char name[DNS_MAXNAMELEN+1];

							snprintf(name, sizeof(name), "%s.%s", label, soa->origin);
							rrlist_add(t, AUTHORITY, DNS_RRTYPE_RR, (void *)r, name);
						}
						t->sort_level++;
						mydns_rr_free(rr);
#if DEBUG_ENABLED && DEBUG_RESOLVE
						Debug("%s: FOUND GLUE", desctask(t));
#endif
						return;
					}
				}
			}
		}

		/* Nothing added - try empty label */
#if DEBUG_ENABLED && DEBUG_RESOLVE
		Debug("%s: Checking for NS (AUTHORITY) for empty label", desctask(t));
#endif
		if ((rr = find_rr(t, soa, DNS_QTYPE_NS, label)))
		{
			for (r = rr; r; r = r->next)
				rrlist_add(t, AUTHORITY, DNS_RRTYPE_RR, (void *)r, soa->origin);
			t->sort_level++;
			mydns_rr_free(rr);
		}
	}
}
/*--- add_authority_ns() ------------------------------------------------------------------------*/


/**************************************************************************************************
	RESOLVE_LABEL
	Examine `label' (or a wildcard).  Add any relevant records.
	Returns nonzero if resolution is complete (because matches were found), else 0.
**************************************************************************************************/
static int
resolve_label(TASK *t, datasection_t section, dns_qtype_t qtype,
				  char *fqdn, MYDNS_SOA *soa, char *label, int full_match, int level)
{
	register MYDNS_RR *rr = NULL;
	register int rv = 0;

#if DEBUG_ENABLED && DEBUG_RESOLVE
	Debug("%s: resolve_label(%s, %s, \"%s\", (%s), \"%s\", %d, %d)",
			desctask(t), resolve_datasection_str[section], mydns_qtype_str(qtype), fqdn,
			soa->origin, label, full_match, level);
#endif

	/* Do any records match this label exactly? */
	/* Only check this if the label is the first in the list */
	if (full_match)
	{
		if ((rr = find_rr(t, soa, DNS_QTYPE_ANY, label)))
		{
			rv = process_rr(t, section, qtype, fqdn, soa, label, rr, level);
			mydns_rr_free(rr);
			add_authority_ns(t, section, soa, label);
			return (rv);
		}
	}

	/* No exact match.  If `label' isn't empty, replace the first part of the label with `*' and
		check for wildcard matches. */
	if (*label && !rv)
	{
		char wclabel[DNS_MAXNAMELEN+1], *c;

		/* Generate wildcarded label, i.e. `*.example' or maybe just `*'. */
		if (!(c = strchr(label, '.')))
			wclabel[0] = '*', wclabel[1] = '\0';
		else
			wclabel[0] = '*', strncpy(wclabel+1, c, sizeof(wclabel)-2);

		if ((rr = find_rr(t, soa, DNS_QTYPE_ANY, wclabel)))
		{
			rv = process_rr(t, section, qtype, fqdn, soa, wclabel, rr, level);
			mydns_rr_free(rr);
			add_authority_ns(t, section, soa, wclabel);
			return (rv);
		}
	}

	/* STILL no match - check for NS records for child delegation */
	if (*label && !rv && (rr = find_rr(t, soa, DNS_QTYPE_NS, label)))
	{
		rv = process_rr(t, section, qtype, fqdn, soa, label, rr, level);
		mydns_rr_free(rr);
		add_authority_ns(t, section, soa, label);
		return (rv);
	}

	return (rv);
}
/*--- resolve_label() ---------------------------------------------------------------------------*/


/**************************************************************************************************
	RESOLVE
	Resolves the specified name, storing all data found in the specified section.
	If `section' is ANSWER, this function will set an error if we lack an authoritative answer.
	Returns number of records inserted, or -1 if an error occurred.
**************************************************************************************************/
int
resolve(TASK *t, datasection_t section, dns_qtype_t qtype, char *fqdn, int level)
{
	char name[DNS_MAXNAMELEN+1];
	register MYDNS_SOA *soa;
	register int rv = 0;
	register char *label;

#if DEBUG_ENABLED && DEBUG_RESOLVE
	Debug("%s: resolve(%s, %s, \"%s\", %d)",
			desctask(t), resolve_datasection_str[section], mydns_qtype_str(qtype), fqdn, level);
#endif

#if STATUS_ENABLED
	if (t->qclass == DNS_CLASS_CHAOS)
		return remote_status(t);
#endif

	if (!axfr_enabled && t->qtype == DNS_QTYPE_AXFR)
		return dnserror(t, DNS_RCODE_REFUSED, ERR_NO_AXFR);

	/* Is the request for a SOA record only? */
	if (t->qtype == DNS_QTYPE_SOA && section == ANSWER)
		return resolve_soa(t, section, fqdn);

	/* Load SOA record for this name - if section is ANSWER and no SOA is found, we're not
		authoritative */
#if DEBUG_ENABLED && DEBUG_RESOLVE
	Debug("%s: Look up soa record for this zone", desctask(t));
#endif
	memset(name, 0, sizeof(name));
	if (!(soa = find_soa(t, fqdn, name)))
	{
		if ((section == ANSWER) && !level)
		{
			if (forward_recursive && t->hdr.rd)
				return recursive_fwd(t);
			else
				return dnserror(t, DNS_RCODE_REFUSED, ERR_ZONE_NOT_FOUND);
		}
		return 0;
	}
	t->zone = soa->id;
	t->minimum_ttl = soa->minimum;

	/* We are authoritative; Set `aa' flag */
	if (section == ANSWER)
	{
#if DEBUG_ENABLED && DEBUG_RESOLVE
		Debug("%s: We are authoritative, zone_id is %u", desctask(t), soa->id);
#endif
		t->hdr.aa = 1;
	}

	/* If the request is ANY, and `fqdn' exactly matches the origin, include SOA */
	if ((qtype == DNS_QTYPE_ANY) && (section == ANSWER) && !strcasecmp(fqdn, soa->origin))
	{
		rrlist_add(t, section, DNS_RRTYPE_SOA, (void *)soa, soa->origin);
		t->sort_level++;
	}

	/* Examine each label in the name, one at a time; look for relevant records */
#if DEBUG_ENABLED && DEBUG_RESOLVE
	Debug("%s: Examining \"%s\", label by label", desctask(t), name);
#endif
	for (label = name; ; label++)
	{
		if (label == name || *label == '.')
		{
			if (label[0] == '.' && label[1]) label++;		/* Advance past leading dot */

			/* Resolve the label; if we find records, we're done. */
			if ((rv = resolve_label(t, section, qtype, fqdn, soa, label, label == name, level)) != 0)
				break;
		}
		if (!*label)
			break;
	}
#if DEBUG_ENABLED && DEBUG_RESOLVE
	Debug("%s: Done examining \"%s\", label by label", desctask(t), name);
#endif

	/* If we got this far and there are NO records, set result and send the SOA */
	if (!level && !t->an.size && !t->ns.size && !t->ar.size)
	{
#if DEBUG_ENABLED && DEBUG_RESOLVE
		Debug("- We are authoritative, but no RRs matched; sending %s with SOA in AUTHORITY section",
				t->name_ok == 1 ? "NOERROR" : "NXDOMAIN");
#endif
		if (t->name_ok)
		{
			t->hdr.rcode = DNS_RCODE_NOERROR;
			t->reason = ERR_NONE;
		}
		else
		{
			t->hdr.rcode = DNS_RCODE_NXDOMAIN;
			t->reason = ERR_NO_MATCHING_RECORDS;
		}
		rrlist_add(t, AUTHORITY, DNS_RRTYPE_SOA, (void *)soa, soa->origin);
		t->sort_level++;
	}

	mydns_soa_free(soa);

	return (rv);
}	
/*--- resolve() ---------------------------------------------------------------------------------*/

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/* NEED_PO */