41 lines
2.2 KiB
C++
41 lines
2.2 KiB
C++
#pragma once
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#include <stdint.h>
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// note - some platforms are confused over these #defines. Specifically, BYTE_ORDER without __ is a false prophet and may lie!
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struct dnsheader {
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unsigned id :16; /* query identification number */
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#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
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/* fields in third byte */
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unsigned qr: 1; /* response flag */
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unsigned opcode: 4; /* purpose of message */
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unsigned aa: 1; /* authoritative answer */
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unsigned tc: 1; /* truncated message */
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unsigned rd: 1; /* recursion desired */
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/* fields in fourth byte */
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unsigned ra: 1; /* recursion available */
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unsigned unused :1; /* unused bits (MBZ as of 4.9.3a3) */
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unsigned ad: 1; /* authentic data from named */
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unsigned cd: 1; /* checking disabled by resolver */
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unsigned rcode :4; /* response code */
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#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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/* fields in third byte */
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unsigned rd :1; /* recursion desired */
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unsigned tc :1; /* truncated message */
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unsigned aa :1; /* authoritative answer */
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unsigned opcode :4; /* purpose of message */
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unsigned qr :1; /* response flag */
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/* fields in fourth byte */
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unsigned rcode :4; /* response code */
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unsigned cd: 1; /* checking disabled by resolver */
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unsigned ad: 1; /* authentic data from named */
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unsigned unused :1; /* unused bits (MBZ as of 4.9.3a3) */
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unsigned ra :1; /* recursion available */
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#endif
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/* remaining bytes */
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uint16_t qdcount; /* number of question entries */
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uint16_t ancount; /* number of answer entries */
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uint16_t nscount; /* number of authority entries */
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uint16_t arcount; /* number of resource entries */
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};
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static_assert(sizeof(dnsheader) == 12, "dnsheader size must be 12");
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