/* $Id: ares_dns.h,v 1.8 2007-02-16 14:22:08 yangtse Exp $ */ /* Copyright 1998 by the Massachusetts Institute of Technology. * * Permission to use, copy, modify, and distribute this * software and its documentation for any purpose and without * fee is hereby granted, provided that the above copyright * notice appear in all copies and that both that copyright * notice and this permission notice appear in supporting * documentation, and that the name of M.I.T. not be used in * advertising or publicity pertaining to distribution of the * software without specific, written prior permission. * M.I.T. makes no representations about the suitability of * this software for any purpose. It is provided "as is" * without express or implied warranty. */ #ifndef ARES__DNS_H #define ARES__DNS_H #define DNS__16BIT(p) (((p)[0] << 8) | (p)[1]) #define DNS__32BIT(p) (((p)[0] << 24) | ((p)[1] << 16) | \ ((p)[2] << 8) | (p)[3]) #define DNS__SET16BIT(p, v) (((p)[0] = (unsigned char)(((v) >> 8) & 0xff)), \ ((p)[1] = (unsigned char)((v) & 0xff))) #define DNS__SET32BIT(p, v) (((p)[0] = (unsigned char)(((v) >> 24) & 0xff)), \ ((p)[1] = (unsigned char)(((v) >> 16) & 0xff)), \ ((p)[2] = (unsigned char)(((v) >> 8) & 0xff)), \ ((p)[3] = (unsigned char)((v) & 0xff))) #if 0 /* we cannot use this approach on systems where we can't access 16/32 bit data on un-aligned addresses */ #define DNS__16BIT(p) ntohs(*(unsigned short*)(p)) #define DNS__32BIT(p) ntohl(*(unsigned long*)(p)) #define DNS__SET16BIT(p, v) *(unsigned short*)(p) = htons(v) #define DNS__SET32BIT(p, v) *(unsigned long*)(p) = htonl(v) #endif /* Macros for parsing a DNS header */ #define DNS_HEADER_QID(h) DNS__16BIT(h) #define DNS_HEADER_QR(h) (((h)[2] >> 7) & 0x1) #define DNS_HEADER_OPCODE(h) (((h)[2] >> 3) & 0xf) #define DNS_HEADER_AA(h) (((h)[2] >> 2) & 0x1) #define DNS_HEADER_TC(h) (((h)[2] >> 1) & 0x1) #define DNS_HEADER_RD(h) ((h)[2] & 0x1) #define DNS_HEADER_RA(h) (((h)[3] >> 7) & 0x1) #define DNS_HEADER_Z(h) (((h)[3] >> 4) & 0x7) #define DNS_HEADER_RCODE(h) ((h)[3] & 0xf) #define DNS_HEADER_QDCOUNT(h) DNS__16BIT((h) + 4) #define DNS_HEADER_ANCOUNT(h) DNS__16BIT((h) + 6) #define DNS_HEADER_NSCOUNT(h) DNS__16BIT((h) + 8) #define DNS_HEADER_ARCOUNT(h) DNS__16BIT((h) + 10) /* Macros for constructing a DNS header */ #define DNS_HEADER_SET_QID(h, v) DNS__SET16BIT(h, v) #define DNS_HEADER_SET_QR(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 7)) #define DNS_HEADER_SET_OPCODE(h, v) ((h)[2] |= (unsigned char)(((v) & 0xf) << 3)) #define DNS_HEADER_SET_AA(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 2)) #define DNS_HEADER_SET_TC(h, v) ((h)[2] |= (unsigned char)(((v) & 0x1) << 1)) #define DNS_HEADER_SET_RD(h, v) ((h)[2] |= (unsigned char)((v) & 0x1)) #define DNS_HEADER_SET_RA(h, v) ((h)[3] |= (unsigned char)(((v) & 0x1) << 7)) #define DNS_HEADER_SET_Z(h, v) ((h)[3] |= (unsigned char)(((v) & 0x7) << 4)) #define DNS_HEADER_SET_RCODE(h, v) ((h)[3] |= (unsigned char)((v) & 0xf)) #define DNS_HEADER_SET_QDCOUNT(h, v) DNS__SET16BIT((h) + 4, v) #define DNS_HEADER_SET_ANCOUNT(h, v) DNS__SET16BIT((h) + 6, v) #define DNS_HEADER_SET_NSCOUNT(h, v) DNS__SET16BIT((h) + 8, v) #define DNS_HEADER_SET_ARCOUNT(h, v) DNS__SET16BIT((h) + 10, v) /* Macros for parsing the fixed part of a DNS question */ #define DNS_QUESTION_TYPE(q) DNS__16BIT(q) #define DNS_QUESTION_CLASS(q) DNS__16BIT((q) + 2) /* Macros for constructing the fixed part of a DNS question */ #define DNS_QUESTION_SET_TYPE(q, v) DNS__SET16BIT(q, v) #define DNS_QUESTION_SET_CLASS(q, v) DNS__SET16BIT((q) + 2, v) /* Macros for parsing the fixed part of a DNS resource record */ #define DNS_RR_TYPE(r) DNS__16BIT(r) #define DNS_RR_CLASS(r) DNS__16BIT((r) + 2) #define DNS_RR_TTL(r) DNS__32BIT((r) + 4) #define DNS_RR_LEN(r) DNS__16BIT((r) + 8) /* Macros for constructing the fixed part of a DNS resource record */ #define DNS_RR_SET_TYPE(r) DNS__SET16BIT(r, v) #define DNS_RR_SET_CLASS(r) DNS__SET16BIT((r) + 2, v) #define DNS_RR_SET_TTL(r) DNS__SET32BIT((r) + 4, v) #define DNS_RR_SET_LEN(r) DNS__SET16BIT((r) + 8, v) #endif /* ARES__DNS_H */