    DNS host name to IP address resolver.

Author

Adam Dunkels adam@dunkels.com

Robert Quattlebaum darco@deepdarc.com

    This file implements a DNS host name to IP address resolver,
    as well as an MDNS responder and resolver.

#include "net/ip/tcpip.h"
#include "net/ip/resolv.h"
#include "net/ip/uip-udp-packet.h"
#include "lib/random.h"
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include "net/ipv6/uip-ds6.h"

Data Structures
struct	dns_answer

struct	dns_hdr

struct	dns_question

struct	namemap

Macros
#define	_DEBUG_ CONTIKI_TARGET_COOJA

#define	CONTIKI_CONF_DEFAULT_HOSTNAME "contiki-"CONTIKI_TARGET_NAME

#define	CONTIKI_TARGET_NAME stringy(BOARD)

#define	DEBUG_PRINTF(...) do { } while(0)

#define	DNS_CLASS_ANY 255

#define	DNS_CLASS_IN 1

#define	DNS_FLAG1_AUTHORATIVE 0x04

#define	DNS_FLAG1_OPCODE_INVERSE 0x08

#define	DNS_FLAG1_OPCODE_STANDARD 0x00

#define	DNS_FLAG1_OPCODE_STATUS 0x10

#define	DNS_FLAG1_RD 0x01

#define	DNS_FLAG1_RESPONSE 0x80

#define	DNS_FLAG1_TRUNC 0x02

#define	DNS_FLAG2_ERR_MASK 0x0f

#define	DNS_FLAG2_ERR_NAME 0x03

#define	DNS_FLAG2_ERR_NONE 0x00

#define	DNS_FLAG2_RA 0x80

#define	DNS_PORT 53

#define	DNS_TYPE_A 1

#define	DNS_TYPE_AAAA 28

#define	DNS_TYPE_ANY 255

#define	DNS_TYPE_CNAME 5

#define	DNS_TYPE_MX 15

#define	DNS_TYPE_NSEC 47

#define	DNS_TYPE_PTR 12

#define	DNS_TYPE_SRV 33

#define	DNS_TYPE_TXT 16

#define	MDNS_PORT 5353

#define	MDNS_RESPONDER_PORT 5354

#define	NATIVE_DNS_TYPE DNS_TYPE_AAAA /* IPv6 */

#define	PRINTF(...) do { } while(0)

#define	RESOLV_AUTO_REMOVE_TRAILING_DOTS RESOLV_CONF_SUPPORTS_MDNS

#define	RESOLV_CONF_MAX_DOMAIN_NAME_SIZE 32

#define	RESOLV_CONF_MAX_MDNS_RETRIES 3

#define	RESOLV_CONF_MAX_RETRIES 4
	The maximum number of retries when asking for a name. More...

#define	RESOLV_CONF_MDNS_INCLUDE_GLOBAL_V6_ADDRS 0

#define	RESOLV_DECODE_INDEX(i) (unsigned char)(uip_ntohs(i-1))

#define	RESOLV_ENCODE_INDEX(i) (uip_htons(i+1))

#define	RESOLV_ENTRIES 4

#define	RESOLV_SUPPORTS_RECORD_EXPIRATION 1

#define	RESOLV_VERIFY_ANSWER_NAMES RESOLV_CONF_SUPPORTS_MDNS

#define	STATE_ASKING 3

#define	STATE_DONE 4

#define	STATE_ERROR 1

#define	STATE_NEW 2

#define	STATE_UNUSED 0

#define	stringy(x) stringy2(x)

#define	stringy2(x) #x

#define	UIP_UDP_BUF ((struct uip_udpip_hdr *)&uip_buf[UIP_LLH_LEN])

#define	VERBOSE_DEBUG 0

Enumerations
enum	{ MDNS_STATE_WAIT_BEFORE_PROBE, MDNS_STATE_PROBING, MDNS_STATE_READY }

Functions
static void	check_entries (void)

static uint8_t	decode_name (const unsigned char query, char dest, const unsigned char *packet)
	Decodes a DNS name from the DNS format into the given string. More...

static uint8_t	dns_name_isequal (const unsigned char queryptr, const char name, const unsigned char *packet)

static unsigned char *	encode_name (unsigned char query, const char nameptr)

static void	mdns_announce_requested (void)

static size_t	mdns_prep_host_announce_packet (void)

static unsigned char *	mdns_write_announce_records (unsigned char queryptr, uint8_t count)

static void	newdata (void)

	PROCESS (resolv_process,"DNS resolver")

	PROCESS (mdns_probe_process,"mDNS probe")

	PROCESS_THREAD (mdns_probe_process, ev, data)

	PROCESS_THREAD (resolv_process, ev, data)

static const char *	remove_trailing_dots (const char *name)

void	resolv_conf (const uip_ipaddr_t *dnsserver)
	Configure a DNS server. More...

static void	resolv_found (char name, uip_ipaddr_t ipaddr)

const char *	resolv_get_hostname (void)
	Returns the local hostname being advertised via MDNS. More...

uip_ipaddr_t *	resolv_getserver (void)
	Obtain the currently configured DNS server. More...

resolv_status_t	resolv_lookup (const char name, uip_ipaddr_t *ipaddr)
	Look up a hostname in the array of known hostnames. More...

void	resolv_query (const char *name)
	Queues a name so that a question for the name will be sent out. More...

void	resolv_set_hostname (const char *hostname)
	Changes the local hostname advertised by MDNS. More...

static unsigned char *	skip_name (unsigned char *query)

static void	start_name_collision_check (clock_time_t after)

int	strcasecmp (const char s1, const char s2)

int	strncasecmp (const char s1, const char s2, size_t n)

Variables
static int	mdns_needs_host_announce

static uint8_t	mdns_state

static struct namemap	names [RESOLV_ENTRIES]

static struct uip_udp_conn *	resolv_conn = NULL

static uip_ipaddr_t	resolv_default_dns_server
	These default values for the DNS server are Google's public DNS: https://developers.google.com/speed/public-dns/docs/using More...

process_event_t	resolv_event_found
	Event that is broadcasted when a DNS name has been resolved. More...

static char	resolv_hostname [RESOLV_CONF_MAX_DOMAIN_NAME_SIZE+1]

static const uip_ipaddr_t	resolv_mdns_addr

static struct etimer	retry

static uint8_t	seqno