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