| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | #ifndef HEADER_CARES_DNS_H |
| 2 | #define HEADER_CARES_DNS_H |
| 3 | |
| 4 | /* Copyright 1998, 2011 by the Massachusetts Institute of Technology. |
| 5 | * |
| 6 | * Permission to use, copy, modify, and distribute this |
| 7 | * software and its documentation for any purpose and without |
| 8 | * fee is hereby granted, provided that the above copyright |
| 9 | * notice appear in all copies and that both that copyright |
| 10 | * notice and this permission notice appear in supporting |
| 11 | * documentation, and that the name of M.I.T. not be used in |
| 12 | * advertising or publicity pertaining to distribution of the |
| 13 | * software without specific, written prior permission. |
| 14 | * M.I.T. makes no representations about the suitability of |
| 15 | * this software for any purpose. It is provided "as is" |
| 16 | * without express or implied warranty. |
| 17 | */ |
| 18 | |
| 19 | /* |
| 20 | * Macro DNS__16BIT reads a network short (16 bit) given in network |
| 21 | * byte order, and returns its value as an unsigned short. |
| 22 | */ |
| 23 | #define DNS__16BIT(p) ((unsigned short)((unsigned int) 0xffff & \ |
| 24 | (((unsigned int)((unsigned char)(p)[0]) << 8U) | \ |
| 25 | ((unsigned int)((unsigned char)(p)[1]))))) |
| 26 | |
| 27 | /* |
| 28 | * Macro DNS__32BIT reads a network long (32 bit) given in network |
| 29 | * byte order, and returns its value as an unsigned int. |
| 30 | */ |
| 31 | #define DNS__32BIT(p) ((unsigned int) \ |
| 32 | (((unsigned int)((unsigned char)(p)[0]) << 24U) | \ |
| 33 | ((unsigned int)((unsigned char)(p)[1]) << 16U) | \ |
| 34 | ((unsigned int)((unsigned char)(p)[2]) << 8U) | \ |
| 35 | ((unsigned int)((unsigned char)(p)[3])))) |
| 36 | |
| 37 | #define DNS__SET16BIT(p, v) (((p)[0] = (unsigned char)(((v) >> 8) & 0xff)), \ |
| 38 | ((p)[1] = (unsigned char)((v) & 0xff))) |
| 39 | #define DNS__SET32BIT(p, v) (((p)[0] = (unsigned char)(((v) >> 24) & 0xff)), \ |
| 40 | ((p)[1] = (unsigned char)(((v) >> 16) & 0xff)), \ |
| 41 | ((p)[2] = (unsigned char)(((v) >> 8) & 0xff)), \ |
| 42 | ((p)[3] = (unsigned char)((v) & 0xff))) |
| 43 | |
| 44 | #if 0 |
| 45 | /* we cannot use this approach on systems where we can't access 16/32 bit |
| 46 | data on un-aligned addresses */ |
| 47 | #define DNS__16BIT(p) ntohs(*(unsigned short*)(p)) |
| 48 | #define DNS__32BIT(p) ntohl(*(unsigned long*)(p)) |
| 49 | #define DNS__SET16BIT(p, v) *(unsigned short*)(p) = htons(v) |
| 50 | #define DNS__SET32BIT(p, v) *(unsigned long*)(p) = htonl(v) |
| 51 | #endif |
| 52 | |
| 53 | /* Macros for parsing a DNS header */ |
| 54 | #define DNS_HEADER_QID(h) DNS__16BIT(h) |
| 55 | #define DNS_HEADER_QR(h) (((h)[2] >> 7) & 0x1) |
| 56 | #define DNS_HEADER_OPCODE(h) (((h)[2] >> 3) & 0xf) |
| 57 | #define DNS_HEADER_AA(h) (((h)[2] >> 2) & 0x1) |
| 58 | #define DNS_HEADER_TC(h) (((h)[2] >> 1) & 0x1) |
| 59 | #define DNS_HEADER_RD(h) ((h)[2] & 0x1) |
| 60 | #define DNS_HEADER_RA(h) (((h)[3] >> 7) & 0x1) |
| 61 | #define DNS_HEADER_Z(h) (((h)[3] >> 4) & 0x7) |
| 62 | #define DNS_HEADER_RCODE(h) ((h)[3] & 0xf) |
| 63 | #define DNS_HEADER_QDCOUNT(h) DNS__16BIT((h) + 4) |
| 64 | #define DNS_HEADER_ANCOUNT(h) DNS__16BIT((h) + 6) |
| 65 | #define DNS_HEADER_NSCOUNT(h) DNS__16BIT((h) + 8) |
| 66 | #define DNS_HEADER_ARCOUNT(h) DNS__16BIT((h) + 10) |
| 67 | |
| 68 | /* Macros for constructing a DNS header */ |
| 69 | #define DNS_HEADER_SET_QID(h, v) DNS__SET16BIT(h, v) |
| 70 | #define DNS_HEADER_SET_QR(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 7)) |
| 71 | #define DNS_HEADER_SET_OPCODE(h, v) ((h)[2] |= (unsigned char)(((v) & 0xf) << 3)) |
| 72 | #define DNS_HEADER_SET_AA(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 2)) |
| 73 | #define DNS_HEADER_SET_TC(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 1)) |
| 74 | #define DNS_HEADER_SET_RD(h, v) ((h)[2] |= (unsigned char)((v) & 0x1)) |
| 75 | #define DNS_HEADER_SET_RA(h, v) ((h)[3] |= (unsigned char)(((v) & 0x1) << 7)) |
| 76 | #define DNS_HEADER_SET_Z(h, v) ((h)[3] |= (unsigned char)(((v) & 0x7) << 4)) |
| 77 | #define DNS_HEADER_SET_RCODE(h, v) ((h)[3] |= (unsigned char)((v) & 0xf)) |
| 78 | #define DNS_HEADER_SET_QDCOUNT(h, v) DNS__SET16BIT((h) + 4, v) |
| 79 | #define DNS_HEADER_SET_ANCOUNT(h, v) DNS__SET16BIT((h) + 6, v) |
| 80 | #define DNS_HEADER_SET_NSCOUNT(h, v) DNS__SET16BIT((h) + 8, v) |
| 81 | #define DNS_HEADER_SET_ARCOUNT(h, v) DNS__SET16BIT((h) + 10, v) |
| 82 | |
| 83 | /* Macros for parsing the fixed part of a DNS question */ |
| 84 | #define DNS_QUESTION_TYPE(q) DNS__16BIT(q) |
| 85 | #define DNS_QUESTION_CLASS(q) DNS__16BIT((q) + 2) |
| 86 | |
| 87 | /* Macros for constructing the fixed part of a DNS question */ |
| 88 | #define DNS_QUESTION_SET_TYPE(q, v) DNS__SET16BIT(q, v) |
| 89 | #define DNS_QUESTION_SET_CLASS(q, v) DNS__SET16BIT((q) + 2, v) |
| 90 | |
| 91 | /* Macros for parsing the fixed part of a DNS resource record */ |
| 92 | #define DNS_RR_TYPE(r) DNS__16BIT(r) |
| 93 | #define DNS_RR_CLASS(r) DNS__16BIT((r) + 2) |
| 94 | #define DNS_RR_TTL(r) DNS__32BIT((r) + 4) |
| 95 | #define DNS_RR_LEN(r) DNS__16BIT((r) + 8) |
| 96 | |
| 97 | /* Macros for constructing the fixed part of a DNS resource record */ |
| 98 | #define DNS_RR_SET_TYPE(r, v) DNS__SET16BIT(r, v) |
| 99 | #define DNS_RR_SET_CLASS(r, v) DNS__SET16BIT((r) + 2, v) |
| 100 | #define DNS_RR_SET_TTL(r, v) DNS__SET32BIT((r) + 4, v) |
| 101 | #define DNS_RR_SET_LEN(r, v) DNS__SET16BIT((r) + 8, v) |
| 102 | |
| 103 | #endif /* HEADER_CARES_DNS_H */ |