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