156 lines
3.2 KiB
C
156 lines
3.2 KiB
C
#ifndef _IPXE_DNS_H
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#define _IPXE_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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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdint.h>
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#include <ipxe/in.h>
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/** DNS server port */
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#define DNS_PORT 53
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/** An RFC1035-encoded DNS name */
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struct dns_name {
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/** Start of data */
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void *data;
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/** Offset of name within data */
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size_t offset;
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/** Total length of data */
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size_t len;
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};
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/**
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* Test for a DNS compression pointer
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*
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* @v byte Initial byte
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* @ret is_compressed Is a compression pointer
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*/
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#define DNS_IS_COMPRESSED( byte ) ( (byte) & 0xc0 )
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/**
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* Extract DNS compression pointer
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*
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* @v word Initial word
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* @ret offset Offset
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*/
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#define DNS_COMPRESSED_OFFSET( word ) ( (word) & ~0xc000 )
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/**
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* Extract DNS label length
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*
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* @v byte Initial byte
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* @ret len Label length
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*/
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#define DNS_LABEL_LEN( byte ) ( (byte) & ~0xc0 )
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/** Maximum length of a single DNS label */
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#define DNS_MAX_LABEL_LEN 0x3f
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/** Maximum length of a DNS name (mandated by RFC1035 section 2.3.4) */
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#define DNS_MAX_NAME_LEN 255
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/** Maximum depth of CNAME recursion
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*
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* This is a policy decision.
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*/
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#define DNS_MAX_CNAME_RECURSION 32
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/** A DNS packet header */
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struct dns_header {
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/** Query identifier */
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uint16_t id;
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/** Flags */
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uint16_t flags;
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/** Number of question records */
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uint16_t qdcount;
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/** Number of answer records */
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uint16_t ancount;
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/** Number of name server records */
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uint16_t nscount;
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/** Number of additional records */
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uint16_t arcount;
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} __attribute__ (( packed ));
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/** Recursion desired flag */
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#define DNS_FLAG_RD 0x0100
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/** A DNS question */
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struct dns_question {
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/** Query type */
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uint16_t qtype;
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/** Query class */
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uint16_t qclass;
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} __attribute__ (( packed ));
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/** DNS class "IN" */
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#define DNS_CLASS_IN 1
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/** A DNS resource record */
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struct dns_rr_common {
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/** Type */
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uint16_t type;
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/** Class */
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uint16_t class;
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/** Time to live */
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uint32_t ttl;
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/** Resource data length */
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uint16_t rdlength;
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} __attribute__ (( packed ));
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/** Type of a DNS "A" record */
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#define DNS_TYPE_A 1
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/** A DNS "A" record */
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struct dns_rr_a {
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/** Common fields */
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struct dns_rr_common common;
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/** IPv4 address */
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struct in_addr in_addr;
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} __attribute__ (( packed ));
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/** Type of a DNS "AAAA" record */
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#define DNS_TYPE_AAAA 28
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/** A DNS "AAAA" record */
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struct dns_rr_aaaa {
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/** Common fields */
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struct dns_rr_common common;
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/** IPv6 address */
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struct in6_addr in6_addr;
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} __attribute__ (( packed ));
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/** Type of a DNS "NAME" record */
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#define DNS_TYPE_CNAME 5
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/** A DNS "CNAME" record */
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struct dns_rr_cname {
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/** Common fields */
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struct dns_rr_common common;
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} __attribute__ (( packed ));
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/** A DNS resource record */
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union dns_rr {
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/** Common fields */
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struct dns_rr_common common;
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/** "A" record */
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struct dns_rr_a a;
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/** "AAAA" record */
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struct dns_rr_aaaa aaaa;
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/** "CNAME" record */
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struct dns_rr_cname cname;
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};
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extern int dns_encode ( const char *string, struct dns_name *name );
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extern int dns_decode ( struct dns_name *name, char *data, size_t len );
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extern int dns_compare ( struct dns_name *first, struct dns_name *second );
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extern int dns_copy ( struct dns_name *src, struct dns_name *dst );
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extern int dns_skip ( struct dns_name *name );
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#endif /* _IPXE_DNS_H */
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