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- #ifndef HEADER_CARES_DNS_H
- #define HEADER_CARES_DNS_H
- /* Copyright 1998, 2011 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.
- */
- /*
- * NOTE TO INTEGRATORS:
- *
- * This header is made public due to legacy projects relying on it.
- * Please do not use the macros within this header, or include this
- * header in your project as it may be removed in the future.
- */
- /*
- * Macro DNS__16BIT reads a network short (16 bit) given in network
- * byte order, and returns its value as an unsigned short.
- */
- #define DNS__16BIT(p) ((unsigned short)((unsigned int) 0xffff & \
- (((unsigned int)((unsigned char)(p)[0]) << 8U) | \
- ((unsigned int)((unsigned char)(p)[1])))))
- /*
- * Macro DNS__32BIT reads a network long (32 bit) given in network
- * byte order, and returns its value as an unsigned int.
- */
- #define DNS__32BIT(p) ((unsigned int) \
- (((unsigned int)((unsigned char)(p)[0]) << 24U) | \
- ((unsigned int)((unsigned char)(p)[1]) << 16U) | \
- ((unsigned int)((unsigned char)(p)[2]) << 8U) | \
- ((unsigned int)((unsigned char)(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, v) DNS__SET16BIT(r, v)
- #define DNS_RR_SET_CLASS(r, v) DNS__SET16BIT((r) + 2, v)
- #define DNS_RR_SET_TTL(r, v) DNS__SET32BIT((r) + 4, v)
- #define DNS_RR_SET_LEN(r, v) DNS__SET16BIT((r) + 8, v)
- #endif /* HEADER_CARES_DNS_H */
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