1 files changed, 282 insertions, 0 deletions
diff --git a/lib/dns/byaddr.c b/lib/dns/byaddr.c
new file mode 100644
index 0000000..8fa668a
--- /dev/null
+++ b/lib/dns/byaddr.c
@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+
+#include <stdbool.h>
+
+#include <isc/mem.h>
+#include <isc/netaddr.h>
+#include <isc/print.h>
+#include <isc/result.h>
+#include <isc/string.h> /* Required for HP/UX (and others?) */
+#include <isc/task.h>
+#include <isc/util.h>
+
+#include <dns/byaddr.h>
+#include <dns/db.h>
+#include <dns/events.h>
+#include <dns/lookup.h>
+#include <dns/rdata.h>
+#include <dns/rdataset.h>
+#include <dns/rdatastruct.h>
+#include <dns/resolver.h>
+#include <dns/view.h>
+
+/*
+ * XXXRTH  We could use a static event...
+ */
+
+static char hex_digits[] = { '0', '1', '2', '3', '4', '5', '6', '7',
+			     '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+
+isc_result_t
+dns_byaddr_createptrname(const isc_netaddr_t *address, unsigned int options,
+			 dns_name_t *name) {
+	char textname[128];
+	const unsigned char *bytes;
+	int i;
+	char *cp;
+	isc_buffer_t buffer;
+	unsigned int len;
+
+	REQUIRE(address != NULL);
+	UNUSED(options);
+
+	/*
+	 * We create the text representation and then convert to a
+	 * dns_name_t.  This is not maximally efficient, but it keeps all
+	 * of the knowledge of wire format in the dns_name_ routines.
+	 */
+
+	bytes = (const unsigned char *)(&address->type);
+	if (address->family == AF_INET) {
+		(void)snprintf(textname, sizeof(textname),
+			       "%u.%u.%u.%u.in-addr.arpa.",
+			       ((unsigned int)bytes[3] & 0xffU),
+			       ((unsigned int)bytes[2] & 0xffU),
+			       ((unsigned int)bytes[1] & 0xffU),
+			       ((unsigned int)bytes[0] & 0xffU));
+	} else if (address->family == AF_INET6) {
+		size_t remaining;
+
+		cp = textname;
+		for (i = 15; i >= 0; i--) {
+			*cp++ = hex_digits[bytes[i] & 0x0f];
+			*cp++ = '.';
+			*cp++ = hex_digits[(bytes[i] >> 4) & 0x0f];
+			*cp++ = '.';
+		}
+		remaining = sizeof(textname) - (cp - textname);
+		strlcpy(cp, "ip6.arpa.", remaining);
+	} else {
+		return (ISC_R_NOTIMPLEMENTED);
+	}
+
+	len = (unsigned int)strlen(textname);
+	isc_buffer_init(&buffer, textname, len);
+	isc_buffer_add(&buffer, len);
+	return (dns_name_fromtext(name, &buffer, dns_rootname, 0, NULL));
+}
+
+struct dns_byaddr {
+	/* Unlocked. */
+	unsigned int magic;
+	isc_mem_t *mctx;
+	isc_mutex_t lock;
+	dns_fixedname_t name;
+	/* Locked by lock. */
+	unsigned int options;
+	dns_lookup_t *lookup;
+	isc_task_t *task;
+	dns_byaddrevent_t *event;
+	bool canceled;
+};
+
+#define BYADDR_MAGIC	ISC_MAGIC('B', 'y', 'A', 'd')
+#define VALID_BYADDR(b) ISC_MAGIC_VALID(b, BYADDR_MAGIC)
+
+#define MAX_RESTARTS 16
+
+static isc_result_t
+copy_ptr_targets(dns_byaddr_t *byaddr, dns_rdataset_t *rdataset) {
+	isc_result_t result;
+	dns_name_t *name;
+	dns_rdata_t rdata = DNS_RDATA_INIT;
+
+	/*
+	 * The caller must be holding the byaddr's lock.
+	 */
+
+	result = dns_rdataset_first(rdataset);
+	while (result == ISC_R_SUCCESS) {
+		dns_rdata_ptr_t ptr;
+		dns_rdataset_current(rdataset, &rdata);
+		result = dns_rdata_tostruct(&rdata, &ptr, NULL);
+		if (result != ISC_R_SUCCESS) {
+			return (result);
+		}
+		name = isc_mem_get(byaddr->mctx, sizeof(*name));
+		dns_name_init(name, NULL);
+		dns_name_dup(&ptr.ptr, byaddr->mctx, name);
+		dns_rdata_freestruct(&ptr);
+		ISC_LIST_APPEND(byaddr->event->names, name, link);
+		dns_rdata_reset(&rdata);
+		result = dns_rdataset_next(rdataset);
+	}
+	if (result == ISC_R_NOMORE) {
+		result = ISC_R_SUCCESS;
+	}
+
+	return (result);
+}
+
+static void
+lookup_done(isc_task_t *task, isc_event_t *event) {
+	dns_byaddr_t *byaddr = event->ev_arg;
+	dns_lookupevent_t *levent;
+	isc_result_t result;
+
+	REQUIRE(event->ev_type == DNS_EVENT_LOOKUPDONE);
+	REQUIRE(VALID_BYADDR(byaddr));
+	REQUIRE(byaddr->task == task);
+
+	UNUSED(task);
+
+	levent = (dns_lookupevent_t *)event;
+
+	if (levent->result == ISC_R_SUCCESS) {
+		result = copy_ptr_targets(byaddr, levent->rdataset);
+		byaddr->event->result = result;
+	} else {
+		byaddr->event->result = levent->result;
+	}
+	isc_event_free(&event);
+	isc_task_sendanddetach(&byaddr->task, (isc_event_t **)&byaddr->event);
+}
+
+static void
+bevent_destroy(isc_event_t *event) {
+	dns_byaddrevent_t *bevent;
+	dns_name_t *name, *next_name;
+	isc_mem_t *mctx;
+
+	REQUIRE(event->ev_type == DNS_EVENT_BYADDRDONE);
+	mctx = event->ev_destroy_arg;
+	bevent = (dns_byaddrevent_t *)event;
+
+	for (name = ISC_LIST_HEAD(bevent->names); name != NULL;
+	     name = next_name)
+	{
+		next_name = ISC_LIST_NEXT(name, link);
+		ISC_LIST_UNLINK(bevent->names, name, link);
+		dns_name_free(name, mctx);
+		isc_mem_put(mctx, name, sizeof(*name));
+	}
+	isc_mem_put(mctx, event, event->ev_size);
+}
+
+isc_result_t
+dns_byaddr_create(isc_mem_t *mctx, const isc_netaddr_t *address,
+		  dns_view_t *view, unsigned int options, isc_task_t *task,
+		  isc_taskaction_t action, void *arg, dns_byaddr_t **byaddrp) {
+	isc_result_t result;
+	dns_byaddr_t *byaddr;
+	isc_event_t *ievent;
+
+	byaddr = isc_mem_get(mctx, sizeof(*byaddr));
+	byaddr->mctx = NULL;
+	isc_mem_attach(mctx, &byaddr->mctx);
+	byaddr->options = options;
+
+	byaddr->event = isc_mem_get(mctx, sizeof(*byaddr->event));
+	ISC_EVENT_INIT(byaddr->event, sizeof(*byaddr->event), 0, NULL,
+		       DNS_EVENT_BYADDRDONE, action, arg, byaddr,
+		       bevent_destroy, mctx);
+	byaddr->event->result = ISC_R_FAILURE;
+	ISC_LIST_INIT(byaddr->event->names);
+
+	byaddr->task = NULL;
+	isc_task_attach(task, &byaddr->task);
+
+	isc_mutex_init(&byaddr->lock);
+
+	dns_fixedname_init(&byaddr->name);
+
+	result = dns_byaddr_createptrname(address, options,
+					  dns_fixedname_name(&byaddr->name));
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup_lock;
+	}
+
+	byaddr->lookup = NULL;
+	result = dns_lookup_create(mctx, dns_fixedname_name(&byaddr->name),
+				   dns_rdatatype_ptr, view, 0, task,
+				   lookup_done, byaddr, &byaddr->lookup);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup_lock;
+	}
+
+	byaddr->canceled = false;
+	byaddr->magic = BYADDR_MAGIC;
+
+	*byaddrp = byaddr;
+
+	return (ISC_R_SUCCESS);
+
+cleanup_lock:
+	isc_mutex_destroy(&byaddr->lock);
+
+	ievent = (isc_event_t *)byaddr->event;
+	isc_event_free(&ievent);
+	byaddr->event = NULL;
+
+	isc_task_detach(&byaddr->task);
+
+	isc_mem_putanddetach(&mctx, byaddr, sizeof(*byaddr));
+
+	return (result);
+}
+
+void
+dns_byaddr_cancel(dns_byaddr_t *byaddr) {
+	REQUIRE(VALID_BYADDR(byaddr));
+
+	LOCK(&byaddr->lock);
+
+	if (!byaddr->canceled) {
+		byaddr->canceled = true;
+		if (byaddr->lookup != NULL) {
+			dns_lookup_cancel(byaddr->lookup);
+		}
+	}
+
+	UNLOCK(&byaddr->lock);
+}
+
+void
+dns_byaddr_destroy(dns_byaddr_t **byaddrp) {
+	dns_byaddr_t *byaddr;
+
+	REQUIRE(byaddrp != NULL);
+	byaddr = *byaddrp;
+	*byaddrp = NULL;
+	REQUIRE(VALID_BYADDR(byaddr));
+	REQUIRE(byaddr->event == NULL);
+	REQUIRE(byaddr->task == NULL);
+	dns_lookup_destroy(&byaddr->lookup);
+
+	isc_mutex_destroy(&byaddr->lock);
+	byaddr->magic = 0;
+	isc_mem_putanddetach(&byaddr->mctx, byaddr, sizeof(*byaddr));
+}