1 /* $NetBSD: ecs.c,v 1.6 2023/01/25 21:43:30 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