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https://github.com/ipxe/ipxe
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118 lines
2.4 KiB
C
118 lines
2.4 KiB
C
#ifndef _GPXE_DNS_H
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#define _GPXE_DNS_H
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/** @file
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*
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* DNS protocol
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*
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*/
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#include <stdint.h>
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#include <gpxe/in.h>
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#include <gpxe/async.h>
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#include <gpxe/retry.h>
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/*
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* Constants
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*
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*/
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#define DNS_TYPE_A 1
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#define DNS_TYPE_CNAME 5
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#define DNS_TYPE_ANY 255
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#define DNS_CLASS_IN 1
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#define DNS_CLASS_CS 2
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#define DNS_CLASS_CH 3
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#define DNS_CLASS_HS 4
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#define DNS_FLAG_QUERY ( 0x00 << 15 )
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#define DNS_FLAG_RESPONSE ( 0x01 << 15 )
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#define DNS_FLAG_QR(flags) ( (flags) & ( 0x01 << 15 ) )
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#define DNS_FLAG_OPCODE_QUERY ( 0x00 << 11 )
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#define DNS_FLAG_OPCODE_IQUERY ( 0x01 << 11 )
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#define DNS_FLAG_OPCODE_STATUS ( 0x02 << 11 )
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#define DNS_FLAG_OPCODE(flags) ( (flags) & ( 0x0f << 11 ) )
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#define DNS_FLAG_RD ( 0x01 << 8 )
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#define DNS_FLAG_RA ( 0x01 << 7 )
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#define DNS_FLAG_RCODE_OK ( 0x00 << 0 )
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#define DNS_FLAG_RCODE_NX ( 0x03 << 0 )
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#define DNS_FLAG_RCODE(flags) ( (flags) & ( 0x0f << 0 ) )
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#define DNS_PORT 53
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#define DNS_MAX_RETRIES 3
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#define DNS_MAX_CNAME_RECURSION 0x30
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/*
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* DNS protocol structures
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*
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*/
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struct dns_header {
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uint16_t id;
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uint16_t flags;
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uint16_t qdcount;
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uint16_t ancount;
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uint16_t nscount;
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uint16_t arcount;
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} __attribute__ (( packed ));
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struct dns_query_info {
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uint16_t qtype;
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uint16_t qclass;
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} __attribute__ (( packed ));
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struct dns_query {
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struct dns_header dns;
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char payload[ 256 + sizeof ( struct dns_query_info ) ];
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} __attribute__ (( packed ));
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struct dns_rr_info_common {
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uint16_t type;
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uint16_t class;
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uint32_t ttl;
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uint16_t rdlength;
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} __attribute__ (( packed ));
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struct dns_rr_info_a {
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struct dns_rr_info_common common;
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struct in_addr in_addr;
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} __attribute__ (( packed ));
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struct dns_rr_info_cname {
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struct dns_rr_info_common common;
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char cname[0];
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} __attribute__ (( packed ));
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union dns_rr_info {
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struct dns_rr_info_common common;
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struct dns_rr_info_a a;
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struct dns_rr_info_cname cname;
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};
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/** A DNS request */
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struct dns_request {
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/** Socket address to fill in with resolved address */
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struct sockaddr *sa;
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/** Current query packet */
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struct dns_query query;
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/** Length of current query packet */
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struct dns_query_info *qinfo;
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/** Recursion counter */
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unsigned int recursion;
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/** Asynchronous operation */
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struct async async;
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/** UDP connection */
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struct udp_connection udp;
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/** Retry timer */
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struct retry_timer timer;
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};
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extern struct in_addr nameserver;
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extern int dns_resolv ( const char *name, struct sockaddr *sa,
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struct async *parent );
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#endif /* _GPXE_DNS_H */
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