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93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
#ifndef DNS_RESOLVER_H
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#define DNS_RESOLVER_H
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#include "stdint.h"
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#include <gpxe/in.h>
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#include "ip.h"
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#include "udp.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_UDP_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 iphdr ip;
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struct udphdr udp;
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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 {
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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 info;
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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 info;
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char cname[0];
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} __attribute__ (( packed ));
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/*
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* Functions in dns.c (used by nmb.c)
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*
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*/
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extern struct dns_header * dns_query ( struct dns_query *query,
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unsigned int query_len,
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struct sockaddr_in *nameserver );
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extern struct dns_rr_info * dns_find_rr ( struct dns_query *query,
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struct dns_header *reply );
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#endif /* DNS_RESOLVER_H */
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