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A working DNS resolver (not yet tied in to anything)

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This commit is contained in:
Michael Brown
2007-01-15 17:31:35 +00:00
parent df0397f334
commit 9af12d5fba
6 changed files with 509 additions and 385 deletions
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109
src/include/gpxe/dns.h Normal file
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#ifndef _GPXE_DNS_H
#define _GPXE_DNS_H
/** @file
*
* DNS protocol
*
*/
#include <stdint.h>
#include <gpxe/in.h>
#include <gpxe/async.h>
#include <gpxe/retry.h>
/*
* Constants
*
*/
#define DNS_TYPE_A 1
#define DNS_TYPE_CNAME 5
#define DNS_TYPE_ANY 255
#define DNS_CLASS_IN 1
#define DNS_CLASS_CS 2
#define DNS_CLASS_CH 3
#define DNS_CLASS_HS 4
#define DNS_FLAG_QUERY ( 0x00 << 15 )
#define DNS_FLAG_RESPONSE ( 0x01 << 15 )
#define DNS_FLAG_QR(flags) ( (flags) & ( 0x01 << 15 ) )
#define DNS_FLAG_OPCODE_QUERY ( 0x00 << 11 )
#define DNS_FLAG_OPCODE_IQUERY ( 0x01 << 11 )
#define DNS_FLAG_OPCODE_STATUS ( 0x02 << 11 )
#define DNS_FLAG_OPCODE(flags) ( (flags) & ( 0x0f << 11 ) )
#define DNS_FLAG_RD ( 0x01 << 8 )
#define DNS_FLAG_RA ( 0x01 << 7 )
#define DNS_FLAG_RCODE_OK ( 0x00 << 0 )
#define DNS_FLAG_RCODE_NX ( 0x03 << 0 )
#define DNS_FLAG_RCODE(flags) ( (flags) & ( 0x0f << 0 ) )
#define DNS_PORT 53
#define DNS_MAX_RETRIES 3
#define DNS_MAX_CNAME_RECURSION 0x30
/*
* DNS protocol structures
*
*/
struct dns_header {
uint16_t id;
uint16_t flags;
uint16_t qdcount;
uint16_t ancount;
uint16_t nscount;
uint16_t arcount;
} __attribute__ (( packed ));
struct dns_query_info {
uint16_t qtype;
uint16_t qclass;
} __attribute__ (( packed ));
struct dns_query {
struct dns_header dns;
char payload[ 256 + sizeof ( struct dns_query_info ) ];
} __attribute__ (( packed ));
struct dns_rr_info_common {
uint16_t type;
uint16_t class;
uint32_t ttl;
uint16_t rdlength;
} __attribute__ (( packed ));
struct dns_rr_info_a {
struct dns_rr_info_common common;
struct in_addr in_addr;
} __attribute__ (( packed ));
struct dns_rr_info_cname {
struct dns_rr_info_common common;
char cname[0];
} __attribute__ (( packed ));
union dns_rr_info {
struct dns_rr_info_common common;
struct dns_rr_info_a a;
struct dns_rr_info_cname cname;
};
struct dns_request {
struct sockaddr_tcpip *st;
struct async async;
struct dns_query query;
struct dns_query_info *qinfo;
unsigned int recursion;
struct udp_connection udp;
struct retry_timer timer;
};
extern int dns_resolv ( const char *name, struct sockaddr_tcpip *st,
struct async *parent );
#endif /* _GPXE_DNS_H */