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Diffstat (limited to 'src/c-ares/ares_dns.h')
| -rw-r--r-- | src/c-ares/ares_dns.h | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/src/c-ares/ares_dns.h b/src/c-ares/ares_dns.h new file mode 100644 index 000000000..79f993b90 --- /dev/null +++ b/src/c-ares/ares_dns.h @@ -0,0 +1,103 @@ +#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. + */ + +/* + * 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 */ |