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
dns_ecs_init(dns_ecs_t * ecs)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
dns_ecs_equals(const dns_ecs_t * ecs1,const dns_ecs_t * ecs2)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
dns_ecs_format(const dns_ecs_t * ecs,char * buf,size_t size)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