1/* MIT License 2 * 3 * Copyright (c) Massachusetts Institute of Technology 4 * Copyright (c) The c-ares project and its contributors 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice (including the next 14 * paragraph) shall be included in all copies or substantial portions of the 15 * Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 23 * SOFTWARE. 24 * 25 * SPDX-License-Identifier: MIT 26 */ 27#ifndef HEADER_CARES_DNS_H 28#define HEADER_CARES_DNS_H 29 30/* 31 * NOTE TO INTEGRATORS: 32 * 33 * This header is made public due to legacy projects relying on it. 34 * Please do not use the macros within this header, or include this 35 * header in your project as it may be removed in the future. 36 */ 37 38 39/* 40 * Macro DNS__16BIT reads a network short (16 bit) given in network 41 * byte order, and returns its value as an unsigned short. 42 */ 43#define DNS__16BIT(p) \ 44 ((unsigned short)((unsigned int)0xffff & \ 45 (((unsigned int)((unsigned char)(p)[0]) << 8U) | \ 46 ((unsigned int)((unsigned char)(p)[1]))))) 47 48/* 49 * Macro DNS__32BIT reads a network long (32 bit) given in network 50 * byte order, and returns its value as an unsigned int. 51 */ 52#define DNS__32BIT(p) \ 53 ((unsigned int)(((unsigned int)((unsigned char)(p)[0]) << 24U) | \ 54 ((unsigned int)((unsigned char)(p)[1]) << 16U) | \ 55 ((unsigned int)((unsigned char)(p)[2]) << 8U) | \ 56 ((unsigned int)((unsigned char)(p)[3])))) 57 58#define DNS__SET16BIT(p, v) \ 59 (((p)[0] = (unsigned char)(((v) >> 8) & 0xff)), \ 60 ((p)[1] = (unsigned char)((v) & 0xff))) 61#define DNS__SET32BIT(p, v) \ 62 (((p)[0] = (unsigned char)(((v) >> 24) & 0xff)), \ 63 ((p)[1] = (unsigned char)(((v) >> 16) & 0xff)), \ 64 ((p)[2] = (unsigned char)(((v) >> 8) & 0xff)), \ 65 ((p)[3] = (unsigned char)((v) & 0xff))) 66 67#if 0 68/* we cannot use this approach on systems where we can't access 16/32 bit 69 data on un-aligned addresses */ 70# define DNS__16BIT(p) ntohs(*(unsigned short *)(p)) 71# define DNS__32BIT(p) ntohl(*(unsigned long *)(p)) 72# define DNS__SET16BIT(p, v) *(unsigned short *)(p) = htons(v) 73# define DNS__SET32BIT(p, v) *(unsigned long *)(p) = htonl(v) 74#endif 75 76/* Macros for parsing a DNS header */ 77#define DNS_HEADER_QID(h) DNS__16BIT(h) 78#define DNS_HEADER_QR(h) (((h)[2] >> 7) & 0x1) 79#define DNS_HEADER_OPCODE(h) (((h)[2] >> 3) & 0xf) 80#define DNS_HEADER_AA(h) (((h)[2] >> 2) & 0x1) 81#define DNS_HEADER_TC(h) (((h)[2] >> 1) & 0x1) 82#define DNS_HEADER_RD(h) ((h)[2] & 0x1) 83#define DNS_HEADER_RA(h) (((h)[3] >> 7) & 0x1) 84#define DNS_HEADER_Z(h) (((h)[3] >> 4) & 0x7) 85#define DNS_HEADER_RCODE(h) ((h)[3] & 0xf) 86#define DNS_HEADER_QDCOUNT(h) DNS__16BIT((h) + 4) 87#define DNS_HEADER_ANCOUNT(h) DNS__16BIT((h) + 6) 88#define DNS_HEADER_NSCOUNT(h) DNS__16BIT((h) + 8) 89#define DNS_HEADER_ARCOUNT(h) DNS__16BIT((h) + 10) 90 91/* Macros for constructing a DNS header */ 92#define DNS_HEADER_SET_QID(h, v) DNS__SET16BIT(h, v) 93#define DNS_HEADER_SET_QR(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 7)) 94#define DNS_HEADER_SET_OPCODE(h, v) \ 95 ((h)[2] |= (unsigned char)(((v) & 0xf) << 3)) 96#define DNS_HEADER_SET_AA(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 2)) 97#define DNS_HEADER_SET_TC(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 1)) 98#define DNS_HEADER_SET_RD(h, v) ((h)[2] |= (unsigned char)((v) & 0x1)) 99#define DNS_HEADER_SET_RA(h, v) ((h)[3] |= (unsigned char)(((v) & 0x1) << 7)) 100#define DNS_HEADER_SET_Z(h, v) ((h)[3] |= (unsigned char)(((v) & 0x7) << 4)) 101#define DNS_HEADER_SET_RCODE(h, v) ((h)[3] |= (unsigned char)((v) & 0xf)) 102#define DNS_HEADER_SET_QDCOUNT(h, v) DNS__SET16BIT((h) + 4, v) 103#define DNS_HEADER_SET_ANCOUNT(h, v) DNS__SET16BIT((h) + 6, v) 104#define DNS_HEADER_SET_NSCOUNT(h, v) DNS__SET16BIT((h) + 8, v) 105#define DNS_HEADER_SET_ARCOUNT(h, v) DNS__SET16BIT((h) + 10, v) 106 107/* Macros for parsing the fixed part of a DNS question */ 108#define DNS_QUESTION_TYPE(q) DNS__16BIT(q) 109#define DNS_QUESTION_CLASS(q) DNS__16BIT((q) + 2) 110 111/* Macros for constructing the fixed part of a DNS question */ 112#define DNS_QUESTION_SET_TYPE(q, v) DNS__SET16BIT(q, v) 113#define DNS_QUESTION_SET_CLASS(q, v) DNS__SET16BIT((q) + 2, v) 114 115/* Macros for parsing the fixed part of a DNS resource record */ 116#define DNS_RR_TYPE(r) DNS__16BIT(r) 117#define DNS_RR_CLASS(r) DNS__16BIT((r) + 2) 118#define DNS_RR_TTL(r) DNS__32BIT((r) + 4) 119#define DNS_RR_LEN(r) DNS__16BIT((r) + 8) 120 121/* Macros for constructing the fixed part of a DNS resource record */ 122#define DNS_RR_SET_TYPE(r, v) DNS__SET16BIT(r, v) 123#define DNS_RR_SET_CLASS(r, v) DNS__SET16BIT((r) + 2, v) 124#define DNS_RR_SET_TTL(r, v) DNS__SET32BIT((r) + 4, v) 125#define DNS_RR_SET_LEN(r, v) DNS__SET16BIT((r) + 8, v) 126 127#endif /* HEADER_CARES_DNS_H */ 128