ares_dns.h (5802B)
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 */