1/*	$NetBSD: byaddr.c,v 1.9 2024/02/21 22:52:05 christos Exp $	*/
2
3/*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * SPDX-License-Identifier: MPL-2.0
7 *
8 * This Source Code Form is subject to the terms of the Mozilla Public
9 * License, v. 2.0. If a copy of the MPL was not distributed with this
10 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
11 *
12 * See the COPYRIGHT file distributed with this work for additional
13 * information regarding copyright ownership.
14 */
15
16/*! \file */
17
18#include <stdbool.h>
19
20#include <isc/mem.h>
21#include <isc/netaddr.h>
22#include <isc/print.h>
23#include <isc/result.h>
24#include <isc/string.h> /* Required for HP/UX (and others?) */
25#include <isc/task.h>
26#include <isc/util.h>
27
28#include <dns/byaddr.h>
29#include <dns/db.h>
30#include <dns/events.h>
31#include <dns/lookup.h>
32#include <dns/rdata.h>
33#include <dns/rdataset.h>
34#include <dns/rdatastruct.h>
35#include <dns/resolver.h>
36#include <dns/view.h>
37
38/*
39 * XXXRTH  We could use a static event...
40 */
41
42static char hex_digits[] = { '0', '1', '2', '3', '4', '5', '6', '7',
43			     '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
44
45isc_result_t
46dns_byaddr_createptrname(const isc_netaddr_t *address, unsigned int options,
47			 dns_name_t *name) {
48	char textname[128];
49	const unsigned char *bytes;
50	int i;
51	char *cp;
52	isc_buffer_t buffer;
53	unsigned int len;
54
55	REQUIRE(address != NULL);
56	UNUSED(options);
57
58	/*
59	 * We create the text representation and then convert to a
60	 * dns_name_t.  This is not maximally efficient, but it keeps all
61	 * of the knowledge of wire format in the dns_name_ routines.
62	 */
63
64	bytes = (const unsigned char *)(&address->type);
65	if (address->family == AF_INET) {
66		(void)snprintf(textname, sizeof(textname),
67			       "%u.%u.%u.%u.in-addr.arpa.",
68			       ((unsigned int)bytes[3] & 0xffU),
69			       ((unsigned int)bytes[2] & 0xffU),
70			       ((unsigned int)bytes[1] & 0xffU),
71			       ((unsigned int)bytes[0] & 0xffU));
72	} else if (address->family == AF_INET6) {
73		size_t remaining;
74
75		cp = textname;
76		for (i = 15; i >= 0; i--) {
77			*cp++ = hex_digits[bytes[i] & 0x0f];
78			*cp++ = '.';
79			*cp++ = hex_digits[(bytes[i] >> 4) & 0x0f];
80			*cp++ = '.';
81		}
82		remaining = sizeof(textname) - (cp - textname);
83		strlcpy(cp, "ip6.arpa.", remaining);
84	} else {
85		return (ISC_R_NOTIMPLEMENTED);
86	}
87
88	len = (unsigned int)strlen(textname);
89	isc_buffer_init(&buffer, textname, len);
90	isc_buffer_add(&buffer, len);
91	return (dns_name_fromtext(name, &buffer, dns_rootname, 0, NULL));
92}
93
94struct dns_byaddr {
95	/* Unlocked. */
96	unsigned int magic;
97	isc_mem_t *mctx;
98	isc_mutex_t lock;
99	dns_fixedname_t name;
100	/* Locked by lock. */
101	unsigned int options;
102	dns_lookup_t *lookup;
103	isc_task_t *task;
104	dns_byaddrevent_t *event;
105	bool canceled;
106};
107
108#define BYADDR_MAGIC	ISC_MAGIC('B', 'y', 'A', 'd')
109#define VALID_BYADDR(b) ISC_MAGIC_VALID(b, BYADDR_MAGIC)
110
111#define MAX_RESTARTS 16
112
113static isc_result_t
114copy_ptr_targets(dns_byaddr_t *byaddr, dns_rdataset_t *rdataset) {
115	isc_result_t result;
116	dns_name_t *name;
117	dns_rdata_t rdata = DNS_RDATA_INIT;
118
119	/*
120	 * The caller must be holding the byaddr's lock.
121	 */
122
123	result = dns_rdataset_first(rdataset);
124	while (result == ISC_R_SUCCESS) {
125		dns_rdata_ptr_t ptr;
126		dns_rdataset_current(rdataset, &rdata);
127		result = dns_rdata_tostruct(&rdata, &ptr, NULL);
128		if (result != ISC_R_SUCCESS) {
129			return (result);
130		}
131		name = isc_mem_get(byaddr->mctx, sizeof(*name));
132		dns_name_init(name, NULL);
133		dns_name_dup(&ptr.ptr, byaddr->mctx, name);
134		dns_rdata_freestruct(&ptr);
135		ISC_LIST_APPEND(byaddr->event->names, name, link);
136		dns_rdata_reset(&rdata);
137		result = dns_rdataset_next(rdataset);
138	}
139	if (result == ISC_R_NOMORE) {
140		result = ISC_R_SUCCESS;
141	}
142
143	return (result);
144}
145
146static void
147lookup_done(isc_task_t *task, isc_event_t *event) {
148	dns_byaddr_t *byaddr = event->ev_arg;
149	dns_lookupevent_t *levent;
150	isc_result_t result;
151
152	REQUIRE(event->ev_type == DNS_EVENT_LOOKUPDONE);
153	REQUIRE(VALID_BYADDR(byaddr));
154	REQUIRE(byaddr->task == task);
155
156	UNUSED(task);
157
158	levent = (dns_lookupevent_t *)event;
159
160	if (levent->result == ISC_R_SUCCESS) {
161		result = copy_ptr_targets(byaddr, levent->rdataset);
162		byaddr->event->result = result;
163	} else {
164		byaddr->event->result = levent->result;
165	}
166	isc_event_free(&event);
167	isc_task_sendanddetach(&byaddr->task, (isc_event_t **)(void *)&byaddr->event);
168}
169
170static void
171bevent_destroy(isc_event_t *event) {
172	dns_byaddrevent_t *bevent;
173	dns_name_t *name, *next_name;
174	isc_mem_t *mctx;
175
176	REQUIRE(event->ev_type == DNS_EVENT_BYADDRDONE);
177	mctx = event->ev_destroy_arg;
178	bevent = (dns_byaddrevent_t *)event;
179
180	for (name = ISC_LIST_HEAD(bevent->names); name != NULL;
181	     name = next_name)
182	{
183		next_name = ISC_LIST_NEXT(name, link);
184		ISC_LIST_UNLINK(bevent->names, name, link);
185		dns_name_free(name, mctx);
186		isc_mem_put(mctx, name, sizeof(*name));
187	}
188	isc_mem_put(mctx, event, event->ev_size);
189}
190
191isc_result_t
192dns_byaddr_create(isc_mem_t *mctx, const isc_netaddr_t *address,
193		  dns_view_t *view, unsigned int options, isc_task_t *task,
194		  isc_taskaction_t action, void *arg, dns_byaddr_t **byaddrp) {
195	isc_result_t result;
196	dns_byaddr_t *byaddr;
197	isc_event_t *ievent;
198
199	byaddr = isc_mem_get(mctx, sizeof(*byaddr));
200	byaddr->mctx = NULL;
201	isc_mem_attach(mctx, &byaddr->mctx);
202	byaddr->options = options;
203
204	byaddr->event = isc_mem_get(mctx, sizeof(*byaddr->event));
205	ISC_EVENT_INIT(byaddr->event, sizeof(*byaddr->event), 0, NULL,
206		       DNS_EVENT_BYADDRDONE, action, arg, byaddr,
207		       bevent_destroy, mctx);
208	byaddr->event->result = ISC_R_FAILURE;
209	ISC_LIST_INIT(byaddr->event->names);
210
211	byaddr->task = NULL;
212	isc_task_attach(task, &byaddr->task);
213
214	isc_mutex_init(&byaddr->lock);
215
216	dns_fixedname_init(&byaddr->name);
217
218	result = dns_byaddr_createptrname(address, options,
219					  dns_fixedname_name(&byaddr->name));
220	if (result != ISC_R_SUCCESS) {
221		goto cleanup_lock;
222	}
223
224	byaddr->lookup = NULL;
225	result = dns_lookup_create(mctx, dns_fixedname_name(&byaddr->name),
226				   dns_rdatatype_ptr, view, 0, task,
227				   lookup_done, byaddr, &byaddr->lookup);
228	if (result != ISC_R_SUCCESS) {
229		goto cleanup_lock;
230	}
231
232	byaddr->canceled = false;
233	byaddr->magic = BYADDR_MAGIC;
234
235	*byaddrp = byaddr;
236
237	return (ISC_R_SUCCESS);
238
239cleanup_lock:
240	isc_mutex_destroy(&byaddr->lock);
241
242	ievent = (isc_event_t *)byaddr->event;
243	isc_event_free(&ievent);
244	byaddr->event = NULL;
245
246	isc_task_detach(&byaddr->task);
247
248	isc_mem_putanddetach(&mctx, byaddr, sizeof(*byaddr));
249
250	return (result);
251}
252
253void
254dns_byaddr_cancel(dns_byaddr_t *byaddr) {
255	REQUIRE(VALID_BYADDR(byaddr));
256
257	LOCK(&byaddr->lock);
258
259	if (!byaddr->canceled) {
260		byaddr->canceled = true;
261		if (byaddr->lookup != NULL) {
262			dns_lookup_cancel(byaddr->lookup);
263		}
264	}
265
266	UNLOCK(&byaddr->lock);
267}
268
269void
270dns_byaddr_destroy(dns_byaddr_t **byaddrp) {
271	dns_byaddr_t *byaddr;
272
273	REQUIRE(byaddrp != NULL);
274	byaddr = *byaddrp;
275	*byaddrp = NULL;
276	REQUIRE(VALID_BYADDR(byaddr));
277	REQUIRE(byaddr->event == NULL);
278	REQUIRE(byaddr->task == NULL);
279	dns_lookup_destroy(&byaddr->lookup);
280
281	isc_mutex_destroy(&byaddr->lock);
282	byaddr->magic = 0;
283	isc_mem_putanddetach(&byaddr->mctx, byaddr, sizeof(*byaddr));
284}
285