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osd-contiki/core/net/resolv.c
Oliver Schmidt 8fa9767d47 Restored Contiki compatibility with non-C99 compilers. 
(and compilers without non-standard extensions like void pointer arithmetic)
2013-03-13 14:40:24 +01:00

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/**
* \addtogroup uip
* @{
*/
/**
* \defgroup uipdns uIP hostname resolver functions
* @{
*
* The uIP DNS resolver functions are used to lookup a hostname and
* map it to a numerical IP address. It maintains a list of resolved
* hostnames that can be queried with the resolv_lookup()
* function. New hostnames can be resolved using the resolv_query()
* function.
*
* The event resolv_event_found is posted when a hostname has been
* resolved. It is up to the receiving process to determine if the
* correct hostname has been found by calling the resolv_lookup()
* function with the hostname.
*/
/**
* \file
* DNS host name to IP address resolver.
* \author Adam Dunkels <adam@dunkels.com>
* \author Robert Quattlebaum <darco@deepdarc.com>
*
* This file implements a DNS host name to IP address resolver,
* as well as an MDNS responder and resolver.
*/
/*
* Copyright (c) 2002-2003, Adam Dunkels.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This file is part of the uIP TCP/IP stack.
*
*
*/
#include "net/tcpip.h"
#include "net/resolv.h"
#include "net/uip-udp-packet.h"
#include "lib/random.h"
#ifndef DEBUG
#define DEBUG defined(CONTIKI_TARGET_COOJA)
#endif
#if UIP_UDP
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#ifndef NULL
#define NULL (void *)0
#endif /* NULL */
#if !defined(__SDCC) && defined(SDCC_REVISION)
#define __SDCC 1
#endif
#if VERBOSE_DEBUG
#define DEBUG_PRINTF(...) printf(__VA_ARGS__)
#else
#define DEBUG_PRINTF(...) do { } while(0)
#endif
#if DEBUG || VERBOSE_DEBUG
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...) do { } while(0)
#endif
#ifdef __SDCC
static int
strncasecmp(const char *s1, const char *s2, size_t n)
{
/* TODO: Add case support! */
return strncmp(s1, s2, n);
}
static int
strcasecmp(const char *s1, const char *s2)
{
/* TODO: Add case support! */
return strcmp(s1, s2);
}
#endif
#define UIP_UDP_BUF ((struct uip_udpip_hdr *)&uip_buf[UIP_LLH_LEN])
/* If RESOLV_CONF_SUPPORTS_MDNS is set, then queries
* for domain names in the local TLD will use mDNS as
* described by draft-cheshire-dnsext-multicastdns.
*/
#ifndef RESOLV_CONF_SUPPORTS_MDNS
#define RESOLV_CONF_SUPPORTS_MDNS (1)
#endif
#ifndef RESOLV_CONF_MDNS_INCLUDE_GLOBAL_V6_ADDRS
#define RESOLV_CONF_MDNS_INCLUDE_GLOBAL_V6_ADDRS (0)
#endif
/** The maximum number of retries when asking for a name. */
#ifndef RESOLV_CONF_MAX_RETRIES
#define RESOLV_CONF_MAX_RETRIES (4)
#endif
#ifndef RESOLV_CONF_MAX_MDNS_RETRIES
#define RESOLV_CONF_MAX_MDNS_RETRIES (3)
#endif
#ifndef RESOLV_CONF_MAX_DOMAIN_NAME_SIZE
#define RESOLV_CONF_MAX_DOMAIN_NAME_SIZE (32)
#endif
#if !defined(CONTIKI_TARGET_NAME) && defined(BOARD)
#define stringy2(x) #x
#define stringy(x) stringy2(x)
#define CONTIKI_TARGET_NAME stringy(BOARD)
#endif
#ifndef CONTIKI_CONF_DEFAULT_HOSTNAME
#ifdef CONTIKI_TARGET_NAME
#define CONTIKI_CONF_DEFAULT_HOSTNAME "contiki-"CONTIKI_TARGET_NAME
#else
#define CONTIKI_CONF_DEFAULT_HOSTNAME "contiki"
#endif
#endif
#define DNS_TYPE_A (1)
#define DNS_TYPE_CNAME (5)
#define DNS_TYPE_PTR (12)
#define DNS_TYPE_MX (15)
#define DNS_TYPE_TXT (16)
#define DNS_TYPE_AAAA (28)
#define DNS_TYPE_SRV (33)
#define DNS_TYPE_ANY (255)
#define DNS_TYPE_NSEC (47)
#define DNS_CLASS_IN (1)
#define DNS_CLASS_ANY (255)
#ifndef DNS_PORT
#define DNS_PORT (53)
#endif
#ifndef MDNS_PORT
#define MDNS_PORT (5353)
#endif
#ifndef MDNS_RESPONDER_PORT
#define MDNS_RESPONDER_PORT (5354)
#endif
/** \internal The DNS message header. */
struct dns_hdr {
uint16_t id;
uint8_t flags1, flags2;
#define DNS_FLAG1_RESPONSE 0x80
#define DNS_FLAG1_OPCODE_STATUS 0x10
#define DNS_FLAG1_OPCODE_INVERSE 0x08
#define DNS_FLAG1_OPCODE_STANDARD 0x00
#define DNS_FLAG1_AUTHORATIVE 0x04
#define DNS_FLAG1_TRUNC 0x02
#define DNS_FLAG1_RD 0x01
#define DNS_FLAG2_RA 0x80
#define DNS_FLAG2_ERR_MASK 0x0f
#define DNS_FLAG2_ERR_NONE 0x00
#define DNS_FLAG2_ERR_NAME 0x03
uint16_t numquestions;
uint16_t numanswers;
uint16_t numauthrr;
uint16_t numextrarr;
};
#define RESOLV_ENCODE_INDEX(i) (uip_htons(i+1))
#define RESOLV_DECODE_INDEX(i) (unsigned char)(uip_ntohs(i-1))
/** These default values for the DNS server are Google's public DNS:
* <https://developers.google.com/speed/public-dns/docs/using>
*/
static uip_ipaddr_t resolv_default_dns_server =
#if UIP_CONF_IPV6
{ { 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 } };
#else /* UIP_CONF_IPV6 */
{ { 8, 8, 8, 8 } };
#endif /* UIP_CONF_IPV6 */
/** \internal The DNS answer message structure. */
struct dns_answer {
/* DNS answer record starts with either a domain name or a pointer
* to a name already present somewhere in the packet. */
uint16_t type;
uint16_t class;
uint16_t ttl[2];
uint16_t len;
#if UIP_CONF_IPV6
uint8_t ipaddr[16];
#else
uint8_t ipaddr[4];
#endif
};
struct namemap {
#define STATE_UNUSED 0
#define STATE_ERROR 1
#define STATE_NEW 2
#define STATE_ASKING 3
#define STATE_DONE 4
uint8_t state;
uint8_t tmr;
uint8_t retries;
uint8_t seqno;
unsigned long expiration;
uint8_t err;
#if RESOLV_CONF_SUPPORTS_MDNS
uint8_t is_mdns:1, is_probe:1;
#endif
uip_ipaddr_t ipaddr;
char name[RESOLV_CONF_MAX_DOMAIN_NAME_SIZE + 1];
};
#ifndef UIP_CONF_RESOLV_ENTRIES
#define RESOLV_ENTRIES 4
#else /* UIP_CONF_RESOLV_ENTRIES */
#define RESOLV_ENTRIES UIP_CONF_RESOLV_ENTRIES
#endif /* UIP_CONF_RESOLV_ENTRIES */
static struct namemap names[RESOLV_ENTRIES];
static uint8_t seqno;
static struct uip_udp_conn *resolv_conn = NULL;
static struct etimer retry;
process_event_t resolv_event_found;
PROCESS(resolv_process, "DNS resolver");
static void resolv_found(char *name, uip_ipaddr_t * ipaddr);
enum {
EVENT_NEW_SERVER = 0
};
/*---------------------------------------------------------------------------*/
#if RESOLV_CONF_SUPPORTS_MDNS
/** \internal The DNS question message structure. */
struct dns_question {
uint16_t type;
uint16_t class;
};
static char resolv_hostname[RESOLV_CONF_MAX_DOMAIN_NAME_SIZE + 1];
enum {
MDNS_STATE_WAIT_BEFORE_PROBE,
MDNS_STATE_PROBING,
MDNS_STATE_READY,
};
static uint8_t mdns_state;
static const uip_ipaddr_t resolv_mdns_addr =
#if UIP_CONF_IPV6
{ { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfb } };
#include "net/uip-ds6.h"
#else /* UIP_CONF_IPV6 */
{ { 224, 0, 0, 251 } };
#endif /* UIP_CONF_IPV6 */
static int mdns_needs_host_announce;
PROCESS(mdns_probe_process, "mDNS probe");
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
/*---------------------------------------------------------------------------*/
/** \internal
* \brief Decodes a DNS name from the DNS format into the given string.
* \return 1 upon success, 0 if the size of the name would be too large.
*
* \note `dest` must point to a buffer with at least
* `RESOLV_CONF_MAX_DOMAIN_NAME_SIZE+1` bytes large.
*/
static int
decode_name(const unsigned char *query, char *dest,
const unsigned char *packet)
{
int len = RESOLV_CONF_MAX_DOMAIN_NAME_SIZE;
unsigned char n = *query++;
//DEBUG_PRINTF("resolver: decoding name: \"");
while(len && n) {
if(n & 0xc0) {
const uint16_t offset = query[0] + ((n & ~0xC0) << 8);
//DEBUG_PRINTF("<skip-to-%d>",offset);
query = packet + offset;
n = *query++;
}
if(!n)
break;
for(; n; n--) {
//DEBUG_PRINTF("%c",*query);
*dest++ = *query++;
if(!--len) {
*dest = 0;
return 0;
}
}
n = *query++;
if(n) {
//DEBUG_PRINTF(".");
*dest++ = '.';
len--;
}
}
//DEBUG_PRINTF("\"\n");
*dest = 0;
return len != 0;
}
/*---------------------------------------------------------------------------*/
/** \internal
*/
static int
dns_name_isequal(const unsigned char *queryptr, const char *name,
const unsigned char *packet)
{
unsigned char n = *queryptr++;
if(*name == 0)
return 0;
while(n) {
if(n & 0xc0) {
queryptr = packet + queryptr[0] + ((n & ~0xC0) << 8);
n = *queryptr++;
}
for(; n; n--) {
if(!*name) {
return 0;
}
if(tolower(*name++) != tolower(*queryptr++)) {
return 0;
}
}
n = *queryptr++;
if((n != 0) && (*name++ != '.')) {
return 0;
}
}
if(*name == '.')
name++;
return name[0] == 0;
}
/*---------------------------------------------------------------------------*/
/** \internal
*/
static unsigned char *
skip_name(unsigned char *query)
{
unsigned char n;
DEBUG_PRINTF("resolver: skip name: ");
do {
n = *query;
if(n & 0xc0) {
DEBUG_PRINTF("<skip-to-%d>", query[0] + ((n & ~0xC0) << 8));
query++;
break;
}
query++;
while(n > 0) {
DEBUG_PRINTF("%c", *query);
++query;
--n;
};
DEBUG_PRINTF(".");
} while(*query != 0);
DEBUG_PRINTF("\n");
return query + 1;
}
/*---------------------------------------------------------------------------*/
/** \internal
*/
static unsigned char *
encode_name(unsigned char *query, const char *nameptr)
{
char *nptr;
--nameptr;
/* Convert hostname into suitable query format. */
do {
uint8_t n = 0;
++nameptr;
nptr = (char *)query;
++query;
for(n = 0; *nameptr != '.' && *nameptr != 0; ++nameptr) {
*query = *nameptr;
++query;
++n;
}
*nptr = n;
} while(*nameptr != 0);
/* End the the name. */
*query++ = 0;
return query;
}
#if RESOLV_CONF_SUPPORTS_MDNS
/*---------------------------------------------------------------------------*/
/** \internal
*/
static void
mdns_announce_requested(void)
{
mdns_needs_host_announce = 1;
}
/*---------------------------------------------------------------------------*/
/** \internal
*/
static void
start_name_collision_check(clock_time_t after)
{
process_exit(&mdns_probe_process);
process_start(&mdns_probe_process, (void *)&after);
}
/*---------------------------------------------------------------------------*/
/** \internal
*/
static unsigned char *
mdns_write_announce_records(unsigned char *queryptr, uint8_t * count)
{
struct dns_answer *ans;
#if UIP_CONF_IPV6
uint8_t i;
for(i = 0; i < UIP_DS6_ADDR_NB; i++) {
if(uip_ds6_if.addr_list[i].isused
#if !RESOLV_CONF_MDNS_INCLUDE_GLOBAL_V6_ADDRS
&& uip_is_addr_link_local(&uip_ds6_if.addr_list[i].ipaddr)
#endif
) {
if(!*count) {
queryptr = encode_name(queryptr, resolv_hostname);
} else {
*queryptr++ = 0xc0;
*queryptr++ = sizeof(struct dns_hdr);
}
ans = (struct dns_answer *)queryptr;
*queryptr++ = (uint8_t) ((DNS_TYPE_AAAA) >> 8);
*queryptr++ = (uint8_t) ((DNS_TYPE_AAAA));
*queryptr++ = (uint8_t) ((DNS_CLASS_IN | 0x8000) >> 8);
*queryptr++ = (uint8_t) ((DNS_CLASS_IN | 0x8000));
*queryptr++ = 0;
*queryptr++ = 0;
*queryptr++ = 0;
*queryptr++ = 120;
*queryptr++ = 0;
*queryptr++ = sizeof(uip_ipaddr_t);
uip_ipaddr_copy((uip_ipaddr_t *) queryptr,
&uip_ds6_if.addr_list[i].ipaddr);
queryptr += sizeof(uip_ipaddr_t);
(*count)++;
}
}
#else
queryptr = encode_name(queryptr, resolv_hostname);
ans = (struct dns_answer *)queryptr;
ans->type = UIP_HTONS(DNS_TYPE_A);
ans->class = UIP_HTONS(DNS_CLASS_IN | 0x8000);
ans->ttl[0] = 0;
ans->ttl[1] = UIP_HTONS(120);
ans->len = UIP_HTONS(sizeof(uip_ipaddr_t));
uip_gethostaddr((uip_ipaddr_t *) ans->ipaddr);
queryptr = (unsigned char *)ans + sizeof(*ans);
(*count)++;
#endif
return queryptr;
}
/*---------------------------------------------------------------------------*/
/** \internal
* Called when we need to announce ourselves
*/
static size_t
mdns_prep_host_announce_packet(void)
{
unsigned char *queryptr;
struct dns_answer *ans;
struct dns_hdr *hdr;
uint8_t total_answers = 0;
hdr = (struct dns_hdr *)uip_appdata;
hdr->flags1 |= DNS_FLAG1_RESPONSE | DNS_FLAG1_AUTHORATIVE;
hdr->numquestions = UIP_HTONS(0);
hdr->numauthrr = 0;
hdr->numextrarr = 0;
queryptr = (unsigned char *)hdr + sizeof(*hdr);
queryptr = mdns_write_announce_records(queryptr, &total_answers);
/* We now need to add an NSEC record to indicate
* that this is all there is.
*/
if(!total_answers) {
queryptr = encode_name(queryptr, resolv_hostname);
} else {
*queryptr++ = 0xc0;
*queryptr++ = sizeof(*hdr);
}
ans = (struct dns_answer *)queryptr;
ans->type = UIP_HTONS(DNS_TYPE_NSEC);
ans->class = UIP_HTONS(DNS_CLASS_IN | 0x8000);
ans->ttl[0] = 0;
ans->ttl[1] = UIP_HTONS(120);
ans->len = UIP_HTONS(8);
queryptr += 10;
*queryptr++ = 0xc0;
*queryptr++ = sizeof(*hdr);
*queryptr++ = 0x00;
*queryptr++ = 0x04;
#if UIP_CONF_IPV6
*queryptr++ = 0x00;
*queryptr++ = 0x00;
*queryptr++ = 0x00;
*queryptr++ = 0x08;
#else
*queryptr++ = 0x40;
*queryptr++ = 0x00;
*queryptr++ = 0x00;
*queryptr++ = 0x00;
#endif
hdr->numanswers = uip_htons(total_answers);
hdr->numextrarr = UIP_HTONS(1);
return (queryptr - (unsigned char *)uip_appdata);
}
#endif // #if RESOLV_CONF_SUPPORTS_MDNS
/*---------------------------------------------------------------------------*/
/** \internal
* Runs through the list of names to see if there are any that have
* not yet been queried and, if so, sends out a query.
*/
static void
check_entries(void)
{
volatile uint8_t i;
uint8_t *query;
register struct dns_hdr *hdr;
register struct namemap *namemapptr;
for(i = 0; i < RESOLV_ENTRIES; ++i) {
namemapptr = &names[i];
if(namemapptr->state == STATE_NEW || namemapptr->state == STATE_ASKING) {
etimer_set(&retry, CLOCK_SECOND / 4);
if(namemapptr->state == STATE_ASKING) {
if(--namemapptr->tmr == 0) {
#if RESOLV_CONF_SUPPORTS_MDNS
if(++namemapptr->retries ==
(namemapptr->is_mdns ? RESOLV_CONF_MAX_MDNS_RETRIES :
RESOLV_CONF_MAX_RETRIES))
#else
if(++namemapptr->retries == RESOLV_CONF_MAX_RETRIES)
#endif
{
/* STATE_ERROR basically means "not found". */
namemapptr->state = STATE_ERROR;
/* Keep the "not found" error valid for 30 seconds */
namemapptr->expiration = clock_seconds() + 30;
resolv_found(namemapptr->name, NULL);
continue;
}
namemapptr->tmr = namemapptr->retries * namemapptr->retries * 3;
#if RESOLV_CONF_SUPPORTS_MDNS
if(namemapptr->is_probe) {
/* Probing retries are much more aggressive, 250ms */
namemapptr->tmr = 2;
}
#endif
} else {
/* Its timer has not run out, so we move on to next
* entry.
*/
continue;
}
} else {
namemapptr->state = STATE_ASKING;
namemapptr->tmr = 1;
namemapptr->retries = 0;
}
hdr = (struct dns_hdr *)uip_appdata;
memset(hdr, 0, sizeof(struct dns_hdr));
hdr->id = RESOLV_ENCODE_INDEX(i);
#if RESOLV_CONF_SUPPORTS_MDNS
if(!namemapptr->is_mdns || namemapptr->is_probe) {
hdr->flags1 = DNS_FLAG1_RD;
}
if(namemapptr->is_mdns) {
hdr->id = 0;
}
#else
hdr->flags1 = DNS_FLAG1_RD;
#endif
hdr->numquestions = UIP_HTONS(1);
query = (char *)uip_appdata + sizeof(*hdr);
query = encode_name(query, namemapptr->name);
#if RESOLV_CONF_SUPPORTS_MDNS
if(namemapptr->is_probe) {
*query++ = (uint8_t) ((DNS_TYPE_ANY) >> 8);
*query++ = (uint8_t) ((DNS_TYPE_ANY));
} else
#endif
{
#if UIP_CONF_IPV6
*query++ = (uint8_t) ((DNS_TYPE_AAAA) >> 8);
*query++ = (uint8_t) ((DNS_TYPE_AAAA));
#else
*query++ = (uint8_t) ((DNS_TYPE_A) >> 8);
*query++ = (uint8_t) ((DNS_TYPE_A));
#endif
}
*query++ = (uint8_t) ((DNS_CLASS_IN) >> 8);
*query++ = (uint8_t) ((DNS_CLASS_IN));
#if RESOLV_CONF_SUPPORTS_MDNS
if(namemapptr->is_mdns) {
#if RESOLV_CONF_SUPPORTS_MDNS
if(namemapptr->is_probe) {
/* This is our conflict detection request.
* In order to be in compliance with the MDNS
* spec, we need to add the records we are proposing
* to the rrauth section.
*/
uint8_t count = 0;
query = mdns_write_announce_records(query, &count);
hdr->numauthrr = UIP_HTONS(count);
}
#endif
uip_udp_packet_sendto(resolv_conn,
uip_appdata,
(query - (uint8_t *) uip_appdata),
&resolv_mdns_addr, UIP_HTONS(MDNS_PORT));
PRINTF("resolver: (i=%d) Sent MDNS request for \"%s\".\n", i,
namemapptr->name);
} else {
uip_udp_packet_sendto(resolv_conn,
uip_appdata,
(query - (uint8_t *) uip_appdata),
&resolv_default_dns_server, UIP_HTONS(DNS_PORT));
PRINTF("resolver: (i=%d) Sent DNS request for \"%s\".\n", i,
namemapptr->name);
}
#else
uip_udp_packet_sendto(resolv_conn,
uip_appdata,
(query - (uint8_t *) uip_appdata),
&resolv_default_dns_server, UIP_HTONS(DNS_PORT));
PRINTF("resolver: (i=%d) Sent DNS request for \"%s\".\n", i,
namemapptr->name);
#endif
break;
}
}
}
/*---------------------------------------------------------------------------*/
/** \internal
* Called when new UDP data arrives.
*/
static void
newdata(void)
{
struct dns_answer *ans;
struct dns_hdr const *hdr = (struct dns_hdr *)uip_appdata;
unsigned char *queryptr = (unsigned char *)hdr + sizeof(*hdr);
register struct namemap *namemapptr;
static uint8_t nquestions, nanswers, nauthrr = 0;
static int8_t i;
/* We only care about the question(s) and the answers. The authrr
* and the extrarr are simply discarded.
*/
nquestions = (uint8_t) uip_ntohs(hdr->numquestions);
nanswers = (uint8_t) uip_ntohs(hdr->numanswers);
DEBUG_PRINTF
("resolver: flags1=0x%02X flags2=0x%02X nquestions=%d, nanswers=%d, nauthrr=%d, nextrarr=%d\n",
hdr->flags1, hdr->flags2, (uint8_t) nquestions, (uint8_t) nanswers,
(uint8_t) uip_ntohs(hdr->numauthrr),
(uint8_t) uip_ntohs(hdr->numextrarr));
/** QUESTION HANDLING SECTION ************************************************/
if(((hdr->flags1 & ~1) == 0) && (hdr->flags2 == 0)) {
/* This is an DNS request! */
#if RESOLV_CONF_SUPPORTS_MDNS
/* Skip requests with no questions. */
if(!nquestions) {
return;
}
queryptr = (unsigned char *)hdr + sizeof(*hdr);
i = 0;
for(; nquestions > 0;
queryptr = skip_name(queryptr) + sizeof(struct dns_question),
nquestions--) {
struct dns_question *question =
(struct dns_question *)skip_name(queryptr);
#if __ARM__
static struct dns_question aligned;
memcpy(&aligned, question, sizeof(aligned));
question = &aligned;
#endif
DEBUG_PRINTF("resolver: Question %d: type=%d class=%d\n", ++i,
uip_htons(question->type), uip_htons(question->class));
if(((uip_ntohs(question->class) & 0x7FFF) != DNS_CLASS_IN)
|| ((question->type != UIP_HTONS(DNS_TYPE_ANY))
&& (question->type != UIP_HTONS(DNS_TYPE_AAAA))
&& (question->type != UIP_HTONS(DNS_TYPE_A))
)) {
/* Skip unrecognised records. */
continue;
}
if(!dns_name_isequal(queryptr, resolv_hostname, uip_appdata)) {
continue;
}
PRINTF("resolver: THIS IS A REQUEST FOR US!!!\n");
if(mdns_state == MDNS_STATE_READY) {
/* We only send immediately if this isn't an MDNS request.
* Otherwise, we schedule ourselves to send later.
*/
if(UIP_UDP_BUF->srcport == UIP_HTONS(MDNS_PORT)) {
mdns_announce_requested();
} else {
uip_udp_packet_sendto(resolv_conn,
uip_appdata,
mdns_prep_host_announce_packet(),
&UIP_UDP_BUF->srcipaddr,
UIP_UDP_BUF->srcport);
}
return;
} else {
PRINTF("resolver: But we are still probing. Waiting...\n");
/* We are still probing. We need to do the mDNS
* probe race condition check here and make sure
* we don't need to delay probing for a second.
*/
nauthrr = (uint8_t) uip_ntohs(hdr->numauthrr);
/* For now, we will always restart the collision check if
* there are *any* authority records present.
* In the future we should follow the spec more closely,
* but this should eventually converge to something reasonable.
*/
if(nauthrr) {
start_name_collision_check(CLOCK_SECOND * 1.5);
}
}
}
#endif
}
/** ANSWER HANDLING SECTION **************************************************/
if(!nanswers) {
DEBUG_PRINTF("resolver: Skipping request/response with no answers.\n");
/* We demand answers! */
return;
}
#if RESOLV_CONF_SUPPORTS_MDNS
if(UIP_UDP_BUF->srcport == UIP_HTONS(MDNS_PORT)
&& hdr->id == 0) {
/* OK, this was from MDNS. Things get a little weird here,
* because we can't use the `id` field. We will look up the
* appropriate request in a later step. */
i = -1;
namemapptr = NULL;
} else
#endif // RESOLV_CONF_SUPPORTS_MDNS
{
/* The ID in the DNS header should be our entry into the name table. */
i = RESOLV_DECODE_INDEX(hdr->id);
namemapptr = &names[i];
if(i >= RESOLV_ENTRIES || i < 0 || namemapptr->state != STATE_ASKING) {
PRINTF("resolver: Bad ID (%04X) on incoming DNS response\n",
uip_ntohs(hdr->id));
return;
}
PRINTF("resolver: Incoming response for \"%s\".\n", namemapptr->name);
namemapptr->state = STATE_ERROR; /* We'll change this to DONE when we find the record. */
namemapptr->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
/* If we remain in the error state, keep it cached for 30 seconds. */
namemapptr->expiration = clock_seconds() + 30;
/* Check for error. If so, call callback to inform. */
if(namemapptr->err != 0) {
namemapptr->state = STATE_ERROR;
resolv_found(namemapptr->name, NULL);
return;
}
}
/* Discard all remaining questions */
for(; nquestions > 0; queryptr += 4, nquestions--) {
if(namemapptr
&& 0 != dns_name_isequal(queryptr, namemapptr->name, uip_appdata)) {
DEBUG_PRINTF("resolver: Question name doesn't look familiar...!\n");
return;
}
queryptr = skip_name(queryptr);
}
/* Answer parsing loop */
while(nanswers > 0) {
ans = (struct dns_answer *)skip_name(queryptr);
#if __ARM__
static struct dns_answer aligned;
memcpy(&aligned, ans, sizeof(aligned));
ans = &aligned;
#endif
#if VERBOSE_DEBUG
static char debug_name[40];
decode_name(queryptr, debug_name, uip_appdata);
DEBUG_PRINTF("resolver: \"%s\", type %d, class %d, ttl %d, length %d\n",
debug_name, uip_ntohs(ans->type),
uip_ntohs(ans->class) & 0x7FFF,
(int)((uint32_t) uip_ntohs(ans->ttl[0]) << 16) | (uint32_t)
uip_ntohs(ans->ttl[1]), uip_ntohs(ans->len));
#endif
/* Check the class and length of the answer to make sure
* it matches what we are expecting
*/
if(((uip_ntohs(ans->class) & 0x7FFF) != DNS_CLASS_IN)
|| (ans->len != UIP_HTONS(sizeof(uip_ipaddr_t)))
) {
goto skip_to_next_answer;
}
#if UIP_CONF_IPV6
if(ans->type != UIP_HTONS(DNS_TYPE_AAAA)) {
goto skip_to_next_answer;
}
#else // UIP_CONF_IPV6
if(ans->type != UIP_HTONS(DNS_TYPE_A)) {
goto skip_to_next_answer;
}
#endif
#if RESOLV_CONF_SUPPORTS_MDNS
if(UIP_UDP_BUF->srcport == UIP_HTONS(MDNS_PORT)
&& hdr->id == 0) {
int8_t available_i = RESOLV_ENTRIES;
DEBUG_PRINTF("resolver: MDNS query.\n");
/* For MDNS, we need to actually look up the name we
* are looking for.
*/
for(i = 0; i < RESOLV_ENTRIES; ++i) {
namemapptr = &names[i];
if(dns_name_isequal(queryptr, namemapptr->name, uip_appdata)) {
break;
}
if((namemapptr->state == STATE_UNUSED)
|| (namemapptr->state == STATE_DONE
&& clock_seconds() > namemapptr->expiration)
) {
available_i = i;
}
}
if(i == RESOLV_ENTRIES) {
DEBUG_PRINTF("resolver: Unsolicited MDNS response.\n");
i = available_i;
namemapptr = &names[i];
if(!decode_name(queryptr, namemapptr->name, uip_appdata)) {
DEBUG_PRINTF("resolver: MDNS name too big to cache.\n");
namemapptr = NULL;
goto skip_to_next_answer;
}
}
if(i == RESOLV_ENTRIES) {
DEBUG_PRINTF
("resolver: Not enough room to keep track of unsolicited MDNS answer.\n");
if(dns_name_isequal(queryptr, resolv_hostname, uip_appdata)) {
/* Oh snap, they say they are us! We had better report them... */
resolv_found(resolv_hostname, (uip_ipaddr_t *) ans->ipaddr);
}
namemapptr = NULL;
goto skip_to_next_answer;
}
namemapptr = &names[i];
} else
#endif // #if RESOLV_CONF_SUPPORTS_MDNS
{
/* This will force us to stop even if there are more answers. */
nanswers = 1;
}
if(namemapptr
&& !dns_name_isequal(queryptr, namemapptr->name, uip_appdata)) {
DEBUG_PRINTF("resolver: Answer name doesn't match question...!\n");
goto skip_to_next_answer;
}
DEBUG_PRINTF("resolver: Answer for \"%s\" is usable.\n",
namemapptr->name);
namemapptr->state = STATE_DONE;
namemapptr->expiration = ans->ttl[1] + (ans->ttl[0] << 8);
namemapptr->expiration += clock_seconds();
uip_ipaddr_copy(&namemapptr->ipaddr, (uip_ipaddr_t *) ans->ipaddr);
resolv_found(namemapptr->name, &namemapptr->ipaddr);
skip_to_next_answer:
queryptr =
(unsigned char *)skip_name(queryptr) + 10 + uip_htons(ans->len);
--nanswers;
}
}
#if RESOLV_CONF_SUPPORTS_MDNS
/*---------------------------------------------------------------------------*/
/**
* \brief Changes the local hostname advertised by MDNS.
* \param hostname The new hostname to advertise.
*/
void
resolv_set_hostname(const char *hostname)
{
strncpy(resolv_hostname, hostname, RESOLV_CONF_MAX_DOMAIN_NAME_SIZE);
/* Add the .local suffix if it isn't already there */
if(strlen(resolv_hostname) < 7
|| strcasecmp(resolv_hostname + strlen(resolv_hostname) - 6,
".local") != 0) {
strncat(resolv_hostname, ".local", RESOLV_CONF_MAX_DOMAIN_NAME_SIZE);
}
PRINTF("resolver: hostname changed to \"%s\"\n", resolv_hostname);
start_name_collision_check(0);
}
/*---------------------------------------------------------------------------*/
/**
* \brief Returns the local hostname being advertised via MDNS.
* \return C-string containing the local hostname.
*/
const char *
resolv_get_hostname(void)
{
return resolv_hostname;
}
/*---------------------------------------------------------------------------*/
/** \internal
* Process for probing for name conflicts.
*/
PROCESS_THREAD(mdns_probe_process, ev, data)
{
static struct etimer delay;
PROCESS_BEGIN();
mdns_state = MDNS_STATE_WAIT_BEFORE_PROBE;
PRINTF("mdns-probe: Process (re)started.\n");
/* Wait extra time if specified in data */
if(NULL != data) {
PRINTF("mdns-probe: Probing will begin in %ld clocks.\n",
(long)*(clock_time_t *) data);
etimer_set(&delay, *(clock_time_t *) data);
PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER);
}
/* We need to wait a random (0-250ms) period of time before
* probing to be in compliance with the MDNS spec. */
etimer_set(&delay, CLOCK_SECOND * (random_rand() & 0xFF) / 1024);
PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER);
/* Begin searching for our name. */
mdns_state = MDNS_STATE_PROBING;
resolv_query(resolv_hostname);
do {
PROCESS_WAIT_EVENT_UNTIL(ev == resolv_event_found);
} while(strcasecmp(resolv_hostname, data) != 0);
mdns_state = MDNS_STATE_READY;
mdns_announce_requested();
PRINTF("mdns-probe: Finished probing.\n");
PROCESS_END();
}
#endif // RESOLV_CONF_SUPPORTS_MDNS
/*---------------------------------------------------------------------------*/
/** \internal
* The main UDP function.
*/
PROCESS_THREAD(resolv_process, ev, data)
{
PROCESS_BEGIN();
memset(names, 0, sizeof(names));
resolv_event_found = process_alloc_event();
PRINTF("resolver: Process started.\n");
resolv_conn = udp_new(NULL, 0, NULL);
resolv_conn->rport = 0;
#if RESOLV_CONF_SUPPORTS_MDNS
PRINTF("resolver: Supports MDNS name resolution.\n");
#endif
#if RESOLV_CONF_SUPPORTS_MDNS
PRINTF("resolver: Supports MDNS responder.\n");
uip_udp_bind(resolv_conn, UIP_HTONS(MDNS_PORT));
#if UIP_CONF_IPV6
uip_ds6_maddr_add(&resolv_mdns_addr);
#endif
resolv_set_hostname(CONTIKI_CONF_DEFAULT_HOSTNAME);
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
while(1) {
PROCESS_WAIT_EVENT();
if(ev == PROCESS_EVENT_TIMER) {
tcpip_poll_udp(resolv_conn);
} else if(ev == tcpip_event) {
if(uip_udp_conn == resolv_conn) {
if(uip_newdata()) {
newdata();
}
if(uip_poll()) {
#if RESOLV_CONF_SUPPORTS_MDNS
if(mdns_needs_host_announce) {
size_t len;
PRINTF("resolver: Announcing that we are \"%s\".\n",
resolv_hostname);
memset(uip_appdata, 0, sizeof(struct dns_hdr));
len = mdns_prep_host_announce_packet();
uip_udp_packet_sendto(resolv_conn,
uip_appdata,
len, &resolv_mdns_addr, UIP_HTONS(MDNS_PORT));
mdns_needs_host_announce = 0;
/* Poll again in case this fired
* at the same time the event timer did.
*/
tcpip_poll_udp(resolv_conn);
} else
#endif
{
check_entries();
}
}
}
}
#if RESOLV_CONF_SUPPORTS_MDNS
if(mdns_needs_host_announce) {
tcpip_poll_udp(resolv_conn);
}
#endif
}
PROCESS_END();
}
/* For removing trailing dots in resolv_query() and resolve_lookup2(). */
static char dns_name_without_dots[RESOLV_CONF_MAX_DOMAIN_NAME_SIZE + 1];
/*---------------------------------------------------------------------------*/
/**
* Queues a name so that a question for the name will be sent out.
*
* \param name The hostname that is to be queried.
*/
void
resolv_query(const char *name)
{
static uint8_t i;
static uint8_t lseq, lseqi;
register struct namemap *nameptr = 0;
lseq = lseqi = 0;
{ /* Remove trailing dots, if present. */
size_t len = strlen(name);
if(name[len - 1] == '.') {
strncpy(dns_name_without_dots, name, sizeof(dns_name_without_dots));
while(len && (dns_name_without_dots[len - 1] == '.')) {
dns_name_without_dots[--len] = 0;
}
name = dns_name_without_dots;
}
}
for(i = 0; i < RESOLV_ENTRIES; ++i) {
nameptr = &names[i];
if(0 == strcasecmp(nameptr->name, name)) {
break;
}
if((nameptr->state == STATE_UNUSED)
|| (nameptr->state == STATE_DONE
&& clock_seconds() > nameptr->expiration)
) {
lseqi = i;
lseq = 255;
} else if(seqno - nameptr->seqno > lseq) {
lseq = seqno - nameptr->seqno;
lseqi = i;
}
}
if(i == RESOLV_ENTRIES) {
i = lseqi;
nameptr = &names[i];
}
PRINTF("resolver: Starting query for \"%s\".\n", name);
memset(nameptr, 0, sizeof(*nameptr));
strncpy(nameptr->name, name, sizeof(nameptr->name));
nameptr->state = STATE_NEW;
nameptr->seqno = seqno;
++seqno;
#if RESOLV_CONF_SUPPORTS_MDNS
{
size_t name_len = strlen(name);
static const char local_suffix[] = "local";
if((name_len > (sizeof(local_suffix) - 1))
&& (0 ==
strcasecmp(name + name_len - (sizeof(local_suffix) - 1),
local_suffix))
) {
PRINTF("resolver: Using MDNS to look up \"%s\".\n", name);
nameptr->is_mdns = 1;
} else {
nameptr->is_mdns = 0;
}
}
nameptr->is_probe = (mdns_state == MDNS_STATE_PROBING)
&& (0 == strcmp(nameptr->name, resolv_hostname));
#endif
/* Force check_entires() to run on our process. */
process_post(&resolv_process, PROCESS_EVENT_TIMER, 0);
}
/*---------------------------------------------------------------------------*/
/**
* Look up a hostname in the array of known hostnames.
*
* \note This function only looks in the internal array of known
* hostnames, it does not send out a query for the hostname if none
* was found. The function resolv_query() can be used to send a query
* for a hostname.
*
*/
resolv_status_t
resolv_lookup(const char *name, uip_ipaddr_t ** ipaddr)
{
resolv_status_t ret = RESOLV_STATUS_UNCACHED;
static uint8_t i;
struct namemap *nameptr;
{ /* Remove trailing dots, if present. */
size_t len = strlen(name);
if(name[len - 1] == '.') {
strncpy(dns_name_without_dots, name, sizeof(dns_name_without_dots) - 1);
name = dns_name_without_dots;
while(len && (dns_name_without_dots[len - 1] == '.')) {
dns_name_without_dots[--len] = 0;
}
}
}
#if UIP_CONF_LOOPBACK_INTERFACE
if(strcmp(name, "localhost")) {
static uip_ipaddr_t loopback =
#if UIP_CONF_IPV6
{ { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } };
#else /* UIP_CONF_IPV6 */
{ { 127, 0, 0, 1 } };
#endif /* UIP_CONF_IPV6 */
if(ipaddr) {
*ipaddr = &loopback;
}
ret = RESOLV_STATUS_CACHED;
}
#endif
/* Walk through the list to see if the name is in there. */
for(i = 0; i < RESOLV_ENTRIES; ++i) {
nameptr = &names[i];
if(strcasecmp(name, nameptr->name) == 0) {
switch (nameptr->state) {
case STATE_DONE:
if(clock_seconds() > nameptr->expiration) {
ret = RESOLV_STATUS_EXPIRED;
} else {
ret = RESOLV_STATUS_CACHED;
}
break;
case STATE_NEW:
case STATE_ASKING:
ret = RESOLV_STATUS_RESOLVING;
break;
case STATE_ERROR: /* Almost certainly a not-found error from server */
if(clock_seconds() >= nameptr->expiration) {
ret = RESOLV_STATUS_NOT_FOUND;
}
break;
}
if(ipaddr) {
*ipaddr = &nameptr->ipaddr;
}
/* Break out of for loop. */
break;
}
}
#if VERBOSE_DEBUG
switch (ret) {
case RESOLV_STATUS_CACHED:{
PRINTF("resolver: Found \"%s\" in cache.\n", name);
const uip_ipaddr_t *addr = *ipaddr;
DEBUG_PRINTF
("resolver: %02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x \n",
((uint8_t *) addr)[0], ((uint8_t *) addr)[1], ((uint8_t *) addr)[2],
((uint8_t *) addr)[3], ((uint8_t *) addr)[4], ((uint8_t *) addr)[5],
((uint8_t *) addr)[6], ((uint8_t *) addr)[7], ((uint8_t *) addr)[8],
((uint8_t *) addr)[9], ((uint8_t *) addr)[10],
((uint8_t *) addr)[11], ((uint8_t *) addr)[12],
((uint8_t *) addr)[13], ((uint8_t *) addr)[14],
((uint8_t *) addr)[15]);
break;
}
default:
DEBUG_PRINTF("resolver: \"%s\" is NOT cached.\n", name);
break;
}
#endif
return ret;
}
/*---------------------------------------------------------------------------*/
/**
* Obtain the currently configured DNS server.
*
* \return A pointer to a 4-byte representation of the IP address of
* the currently configured DNS server or NULL if no DNS server has
* been configured.
*/
uip_ipaddr_t *
resolv_getserver(void)
{
return &resolv_default_dns_server;
}
/*---------------------------------------------------------------------------*/
/**
* Configure a DNS server.
*
* \param dnsserver A pointer to a 4-byte representation of the IP
* address of the DNS server to be configured.
*/
void
resolv_conf(const uip_ipaddr_t * dnsserver)
{
uip_ipaddr_copy(&resolv_default_dns_server, dnsserver);
process_post(&resolv_process, EVENT_NEW_SERVER, &resolv_default_dns_server);
}
/*---------------------------------------------------------------------------*/
/** \internal
* Callback function which is called when a hostname is found.
*
*/
static void
resolv_found(char *name, uip_ipaddr_t * ipaddr)
{
#if RESOLV_CONF_SUPPORTS_MDNS
if(strncasecmp(resolv_hostname, name, strlen(resolv_hostname)) == 0
&& ipaddr
#if UIP_CONF_IPV6
&& !uip_ds6_is_my_addr(ipaddr)
#else
&& uip_ipaddr_cmp(&uip_hostaddr, ipaddr) != 0
#endif
) {
uint8_t i;
if(mdns_state == MDNS_STATE_PROBING) {
/* We found this new name while probing.
* We must now rename ourselves.
*/
PRINTF("resolver: Name collision detected for \"%s\".\n", name);
/* Remove the ".local" suffix. */
resolv_hostname[strlen(resolv_hostname) - 6] = 0;
/* Append the last three hex parts of the link-level address. */
for(i = 0; i < 3; i++) {
uint8_t val = uip_lladdr.addr[(UIP_LLADDR_LEN - 3) + i];
char append_str[4] = "-XX";
append_str[2] = (((val & 0xF) > 9) ? 'a' : '0') + (val & 0xF);
val >>= 4;
append_str[1] = (((val & 0xF) > 9) ? 'a' : '0') + (val & 0xF);
strncat(resolv_hostname, append_str,
sizeof(resolv_hostname) - strlen(resolv_hostname));
}
/* Re-add the .local suffix */
strncat(resolv_hostname, ".local", RESOLV_CONF_MAX_DOMAIN_NAME_SIZE);
start_name_collision_check(CLOCK_SECOND * 5);
} else if(mdns_state == MDNS_STATE_READY) {
/* We found a collision after we had already asserted
* that we owned this name. We need to immediately
* and explicitly begin probing.
*/
PRINTF("resolver: Possible name collision, probing...\n");
start_name_collision_check(0);
}
} else
#endif
#if VERBOSE_DEBUG
if(ipaddr) {
PRINTF("resolver: Found address for \"%s\".\n", name);
PRINTF
("resolver: %02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x \n",
((uint8_t *) ipaddr)[0], ((uint8_t *) ipaddr)[1],
((uint8_t *) ipaddr)[2], ((uint8_t *) ipaddr)[3],
((uint8_t *) ipaddr)[4], ((uint8_t *) ipaddr)[5],
((uint8_t *) ipaddr)[6], ((uint8_t *) ipaddr)[7],
((uint8_t *) ipaddr)[8], ((uint8_t *) ipaddr)[9],
((uint8_t *) ipaddr)[10], ((uint8_t *) ipaddr)[11],
((uint8_t *) ipaddr)[12], ((uint8_t *) ipaddr)[13],
((uint8_t *) ipaddr)[14], ((uint8_t *) ipaddr)[15]);
} else {
PRINTF("resolver: Unable to retrieve address for \"%s\".\n", name);
}
#endif
process_post(PROCESS_BROADCAST, resolv_event_found, name);
}
/*---------------------------------------------------------------------------*/
#endif /* UIP_UDP */
/** @} */
/** @} */
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