Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 1 | /* $NetBSD: res_mkquery.c,v 1.6 2006/01/24 17:40:32 christos Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 1985, 1993 |
| 5 | * The Regents of the University of California. All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * 3. All advertising materials mentioning features or use of this software |
| 16 | * must display the following acknowledgement: |
| 17 | * This product includes software developed by the University of |
| 18 | * California, Berkeley and its contributors. |
| 19 | * 4. Neither the name of the University nor the names of its contributors |
| 20 | * may be used to endorse or promote products derived from this software |
| 21 | * without specific prior written permission. |
| 22 | * |
| 23 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 24 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 25 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 26 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 27 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 28 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 29 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 30 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 31 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 32 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 33 | * SUCH DAMAGE. |
| 34 | */ |
| 35 | |
| 36 | /* |
| 37 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
| 38 | * |
| 39 | * Permission to use, copy, modify, and distribute this software for any |
| 40 | * purpose with or without fee is hereby granted, provided that the above |
| 41 | * copyright notice and this permission notice appear in all copies, and that |
| 42 | * the name of Digital Equipment Corporation not be used in advertising or |
| 43 | * publicity pertaining to distribution of the document or software without |
| 44 | * specific, written prior permission. |
| 45 | * |
| 46 | * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
| 47 | * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
| 48 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
| 49 | * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
| 50 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
| 51 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
| 52 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
| 53 | * SOFTWARE. |
| 54 | */ |
| 55 | |
| 56 | /* |
| 57 | * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") |
| 58 | * Portions Copyright (c) 1996-1999 by Internet Software Consortium. |
| 59 | * |
| 60 | * Permission to use, copy, modify, and distribute this software for any |
| 61 | * purpose with or without fee is hereby granted, provided that the above |
| 62 | * copyright notice and this permission notice appear in all copies. |
| 63 | * |
| 64 | * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES |
| 65 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| 66 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR |
| 67 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| 68 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| 69 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT |
| 70 | * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| 71 | */ |
| 72 | |
Ken Chen | 5471dca | 2019-04-15 15:25:35 +0800 | [diff] [blame] | 73 | #define LOG_TAG "resolv" |
Bernie Innocenti | 3952ccc | 2019-03-03 19:39:53 +0900 | [diff] [blame] | 74 | |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 75 | #include <algorithm> // std::min() |
| 76 | |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 77 | #include <arpa/nameser.h> |
| 78 | #include <netdb.h> |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 79 | #include <netinet/in.h> |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 80 | #include <string.h> |
Bernie Innocenti | f33a63f | 2018-08-30 12:04:03 +0900 | [diff] [blame] | 81 | |
chenbruce | acb832c | 2019-02-20 19:45:50 +0800 | [diff] [blame] | 82 | #include <android-base/logging.h> |
Bernie Innocenti | 10a9028 | 2020-01-23 23:28:00 +0900 | [diff] [blame] | 83 | #include <netd_resolv/resolv.h> // NET_CONTEXT_FLAG_USE_DNS_OVER_TLS |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 84 | |
Bernie Innocenti | 10a9028 | 2020-01-23 23:28:00 +0900 | [diff] [blame] | 85 | #include "res_comp.h" |
| 86 | #include "res_debug.h" |
Bernie Innocenti | 983f02e | 2021-07-01 07:36:56 +0900 | [diff] [blame] | 87 | #include "resolv_private.h" // ResState* |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 88 | |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 89 | // Queries will be padded to a multiple of this length when EDNS0 is active. |
| 90 | constexpr uint16_t kEdns0Padding = 128; |
| 91 | |
Mike Yu | bfb1b34 | 2018-11-06 15:42:36 +0800 | [diff] [blame] | 92 | extern const char* const _res_opcodes[] = { |
| 93 | "QUERY", "IQUERY", "CQUERYM", "CQUERYU", /* experimental */ |
| 94 | "NOTIFY", /* experimental */ |
| 95 | "UPDATE", "6", "7", "8", "9", "10", |
| 96 | "11", "12", "13", "ZONEINIT", "ZONEREF", |
| 97 | }; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 98 | |
Bernie Innocenti | 0848711 | 2019-10-11 21:14:13 +0900 | [diff] [blame] | 99 | // Form all types of queries. Returns the size of the result or -1. |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 100 | int res_nmkquery(int op, // opcode of query |
| 101 | const char* dname, // domain name |
| 102 | int cl, int type, // class and type of query |
| 103 | std::span<const uint8_t> data, // resource record data |
| 104 | std::span<uint8_t> buf, // buffer to put query |
Bernie Innocenti | 0848711 | 2019-10-11 21:14:13 +0900 | [diff] [blame] | 105 | int netcontext_flags) { |
Bernie Innocenti | 9c57593 | 2018-09-07 21:10:25 +0900 | [diff] [blame] | 106 | HEADER* hp; |
chenbruce | c51f121 | 2019-09-12 16:59:33 +0800 | [diff] [blame] | 107 | uint8_t *cp, *ep; |
Bernie Innocenti | 9c57593 | 2018-09-07 21:10:25 +0900 | [diff] [blame] | 108 | int n; |
chenbruce | c51f121 | 2019-09-12 16:59:33 +0800 | [diff] [blame] | 109 | uint8_t *dnptrs[20], **dpp, **lastdnptr; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 110 | |
Ken Chen | ffc224a | 2019-03-19 17:41:28 +0800 | [diff] [blame] | 111 | LOG(DEBUG) << __func__ << ": (" << _res_opcodes[op] << ", " << p_class(cl) << ", " |
| 112 | << p_type(type) << ")"; |
chenbruce | acb832c | 2019-02-20 19:45:50 +0800 | [diff] [blame] | 113 | |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 114 | /* |
| 115 | * Initialize header fields. |
| 116 | */ |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 117 | if (buf.empty() || (buf.size() < HFIXEDSZ)) return (-1); |
| 118 | memset(buf.data(), 0, HFIXEDSZ); |
| 119 | hp = (HEADER*)(void*)buf.data(); |
Luke Huang | dda920f | 2019-02-13 14:05:02 +0800 | [diff] [blame] | 120 | hp->id = htons(arc4random_uniform(65536)); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 121 | hp->opcode = op; |
chenbruce | 018fdb2 | 2019-06-12 18:08:04 +0800 | [diff] [blame] | 122 | hp->rd = true; |
Bernie Innocenti | 0848711 | 2019-10-11 21:14:13 +0900 | [diff] [blame] | 123 | hp->ad = (netcontext_flags & NET_CONTEXT_FLAG_USE_DNS_OVER_TLS) != 0U; |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 124 | hp->rcode = NOERROR; |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 125 | cp = buf.data() + HFIXEDSZ; |
| 126 | ep = buf.data() + buf.size(); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 127 | dpp = dnptrs; |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 128 | *dpp++ = buf.data(); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 129 | *dpp++ = NULL; |
| 130 | lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0]; |
| 131 | /* |
| 132 | * perform opcode specific processing |
| 133 | */ |
| 134 | switch (op) { |
Bernie Innocenti | f40b3bd | 2018-10-10 22:30:12 +0900 | [diff] [blame] | 135 | case QUERY: |
| 136 | [[fallthrough]]; |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 137 | case NS_NOTIFY_OP: |
| 138 | if (ep - cp < QFIXEDSZ) return (-1); |
| 139 | if ((n = dn_comp(dname, cp, ep - cp - QFIXEDSZ, dnptrs, lastdnptr)) < 0) return (-1); |
| 140 | cp += n; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 141 | *reinterpret_cast<uint16_t*>(cp) = htons(type); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 142 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 143 | *reinterpret_cast<uint16_t*>(cp) = htons(cl); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 144 | cp += INT16SZ; |
| 145 | hp->qdcount = htons(1); |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 146 | if (op == QUERY || data.empty()) break; |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 147 | /* |
| 148 | * Make an additional record for completion domain. |
| 149 | */ |
| 150 | if ((ep - cp) < RRFIXEDSZ) return (-1); |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 151 | n = dn_comp((const char*)data.data(), cp, ep - cp - RRFIXEDSZ, dnptrs, lastdnptr); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 152 | if (n < 0) return (-1); |
| 153 | cp += n; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 154 | *reinterpret_cast<uint16_t*>(cp) = htons(ns_t_null); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 155 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 156 | *reinterpret_cast<uint16_t*>(cp) = htons(cl); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 157 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 158 | *reinterpret_cast<uint32_t*>(cp) = htonl(0); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 159 | cp += INT32SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 160 | *reinterpret_cast<uint16_t*>(cp) = htons(0); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 161 | cp += INT16SZ; |
| 162 | hp->arcount = htons(1); |
| 163 | break; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 164 | |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 165 | case IQUERY: |
| 166 | /* |
| 167 | * Initialize answer section |
| 168 | */ |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 169 | if (ep - cp < 1 + RRFIXEDSZ + data.size()) return (-1); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 170 | *cp++ = '\0'; /* no domain name */ |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 171 | *reinterpret_cast<uint16_t*>(cp) = htons(type); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 172 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 173 | *reinterpret_cast<uint16_t*>(cp) = htons(cl); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 174 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 175 | *reinterpret_cast<uint32_t*>(cp) = htonl(0); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 176 | cp += INT32SZ; |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 177 | *reinterpret_cast<uint16_t*>(cp) = htons(data.size()); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 178 | cp += INT16SZ; |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 179 | if (data.size()) { |
| 180 | memcpy(cp, data.data(), data.size()); |
| 181 | cp += data.size(); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 182 | } |
| 183 | hp->ancount = htons(1); |
| 184 | break; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 185 | |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 186 | default: |
| 187 | return (-1); |
| 188 | } |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 189 | return (cp - buf.data()); |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 190 | } |
| 191 | |
Bernie Innocenti | 983f02e | 2021-07-01 07:36:56 +0900 | [diff] [blame] | 192 | int res_nopt(ResState* statp, int n0, /* current offset in buffer */ |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 193 | std::span<uint8_t> buf, /* buffer to put query */ |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 194 | int anslen) /* UDP answer buffer size */ |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 195 | { |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 196 | HEADER* hp = reinterpret_cast<HEADER*>(buf.data()); |
chenbruce | c51f121 | 2019-09-12 16:59:33 +0800 | [diff] [blame] | 197 | uint8_t *cp, *ep; |
| 198 | uint16_t flags = 0; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 199 | |
Bernie Innocenti | 3952ccc | 2019-03-03 19:39:53 +0900 | [diff] [blame] | 200 | LOG(DEBUG) << __func__; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 201 | |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 202 | cp = buf.data() + n0; |
| 203 | ep = buf.data() + buf.size(); |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 204 | |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 205 | if ((ep - cp) < 1 + RRFIXEDSZ) return (-1); |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 206 | |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 207 | *cp++ = 0; /* "." */ |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 208 | |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 209 | // Attach OPT pseudo-RR, as documented in RFC2671 (EDNS0). |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 210 | *reinterpret_cast<uint16_t*>(cp) = htons(ns_t_opt); /* TYPE */ |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 211 | cp += INT16SZ; |
| 212 | if (anslen > 0xffff) anslen = 0xffff; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 213 | *reinterpret_cast<uint16_t*>(cp) = htons(anslen); /* CLASS = UDP payload size */ |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 214 | cp += INT16SZ; |
| 215 | *cp++ = NOERROR; /* extended RCODE */ |
| 216 | *cp++ = 0; /* EDNS version */ |
chenbruce | d8cbb9b | 2019-06-20 18:25:28 +0800 | [diff] [blame] | 217 | if (statp->netcontext_flags & NET_CONTEXT_FLAG_USE_DNS_OVER_TLS) { |
Bernie Innocenti | 3952ccc | 2019-03-03 19:39:53 +0900 | [diff] [blame] | 218 | LOG(DEBUG) << __func__ << ": ENDS0 DNSSEC"; |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 219 | flags |= NS_OPT_DNSSEC_OK; |
| 220 | } |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 221 | *reinterpret_cast<uint16_t*>(cp) = htons(flags); |
Bernie Innocenti | 8ad893f | 2018-08-31 14:09:46 +0900 | [diff] [blame] | 222 | cp += INT16SZ; |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 223 | |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 224 | // EDNS0 padding |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 225 | const uint16_t minlen = static_cast<uint16_t>(cp - buf.data()) + 3 * INT16SZ; |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 226 | const uint16_t extra = minlen % kEdns0Padding; |
| 227 | uint16_t padlen = (kEdns0Padding - extra) % kEdns0Padding; |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 228 | if (minlen > buf.size()) { |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 229 | return -1; |
| 230 | } |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 231 | padlen = std::min(padlen, static_cast<uint16_t>(buf.size() - minlen)); |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 232 | *reinterpret_cast<uint16_t*>(cp) = htons(padlen + 2 * INT16SZ); /* RDLEN */ |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 233 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 234 | *reinterpret_cast<uint16_t*>(cp) = htons(NS_OPT_PADDING); /* OPTION-CODE */ |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 235 | cp += INT16SZ; |
chenbruce | 0d47042 | 2019-03-28 18:44:37 +0800 | [diff] [blame] | 236 | *reinterpret_cast<uint16_t*>(cp) = htons(padlen); /* OPTION-LENGTH */ |
Bernie Innocenti | 136af7b | 2018-10-01 20:46:20 +0900 | [diff] [blame] | 237 | cp += INT16SZ; |
| 238 | memset(cp, 0, padlen); |
| 239 | cp += padlen; |
| 240 | |
| 241 | hp->arcount = htons(ntohs(hp->arcount) + 1); |
chenbruce | c7d6927 | 2021-08-09 14:20:33 +0800 | [diff] [blame] | 242 | return (cp - buf.data()); |
Bernie Innocenti | 318ed2d | 2018-08-30 04:05:20 +0900 | [diff] [blame] | 243 | } |