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ecs.c revision 1.1 
      1 /*	$NetBSD: ecs.c,v 1.1 2024/02/18 20:57:31 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 <string.h>
     19 
     20 #include <isc/buffer.h>
     21 #include <isc/mem.h>
     22 #include <isc/netaddr.h>
     23 #include <isc/print.h>
     24 #include <isc/util.h>
     25 
     26 #include <dns/ecs.h>
     27 #include <dns/nsec.h>
     28 #include <dns/rbt.h>
     29 #include <dns/rdata.h>
     30 #include <dns/rdatatype.h>
     31 #include <dns/result.h>
     32 #include <dns/types.h>
     33 
     34 void
     35 dns_ecs_init(dns_ecs_t *ecs) {
     36 	isc_netaddr_unspec(&ecs->addr);
     37 	ecs->source = 0;
     38 	ecs->scope = 0xff;
     39 }
     40 
     41 bool
     42 dns_ecs_equals(const dns_ecs_t *ecs1, const dns_ecs_t *ecs2) {
     43 	const unsigned char *addr1, *addr2;
     44 	uint8_t mask;
     45 	size_t alen;
     46 
     47 	REQUIRE(ecs1 != NULL && ecs2 != NULL);
     48 
     49 	if (ecs1->source != ecs2->source ||
     50 	    ecs1->addr.family != ecs2->addr.family)
     51 	{
     52 		return (false);
     53 	}
     54 
     55 	alen = (ecs1->source + 7) / 8;
     56 	if (alen == 0) {
     57 		return (true);
     58 	}
     59 
     60 	switch (ecs1->addr.family) {
     61 	case AF_INET:
     62 		INSIST(alen <= 4);
     63 		addr1 = (const unsigned char *)&ecs1->addr.type.in;
     64 		addr2 = (const unsigned char *)&ecs2->addr.type.in;
     65 		break;
     66 	case AF_INET6:
     67 		INSIST(alen <= 16);
     68 		addr1 = (const unsigned char *)&ecs1->addr.type.in6;
     69 		addr2 = (const unsigned char *)&ecs2->addr.type.in6;
     70 		break;
     71 	default:
     72 		UNREACHABLE();
     73 	}
     74 
     75 	/*
     76 	 * Compare all octets except the final octet of the address
     77 	 * prefix.
     78 	 */
     79 	if (alen > 1 && memcmp(addr1, addr2, alen - 1) != 0) {
     80 		return (false);
     81 	}
     82 
     83 	/*
     84 	 * It should not be necessary to mask the final octet; all
     85 	 * bits past the source prefix length are supposed to be 0.
     86 	 * However, it seems prudent not to omit them from the
     87 	 * comparison anyway.
     88 	 */
     89 	mask = (~0U << (8 - (ecs1->source % 8))) & 0xff;
     90 	if (mask == 0) {
     91 		mask = 0xff;
     92 	}
     93 
     94 	if ((addr1[alen - 1] & mask) != (addr2[alen - 1] & mask)) {
     95 		return (false);
     96 	}
     97 
     98 	return (true);
     99 }
    100 
    101 void
    102 dns_ecs_format(const dns_ecs_t *ecs, char *buf, size_t size) {
    103 	size_t len;
    104 	char *p;
    105 
    106 	REQUIRE(ecs != NULL);
    107 	REQUIRE(buf != NULL);
    108 	REQUIRE(size >= DNS_ECS_FORMATSIZE);
    109 
    110 	isc_netaddr_format(&ecs->addr, buf, size);
    111 	len = strlen(buf);
    112 	p = buf + len;
    113 	snprintf(p, size - len, "/%d/%d", ecs->source,
    114 		 ecs->scope == 0xff ? 0 : ecs->scope);
    115 }
    116