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nes-proj/os/net/ipv6/resolv.c

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/*
* 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.
*
*
*/
/**
* \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.
*/
/**
* \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.
*/
#include "net/ipv6/tcpip.h"
#include "net/ipv6/resolv.h"
#include "net/ipv6/uip-udp-packet.h"
#include "net/ipv6/uip-nameserver.h"
#include "lib/random.h"
#ifndef DEBUG
#define DEBUG 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);
}
#else
int strcasecmp(const char *s1, const char *s2);
int strncasecmp(const char *s1, const char *s2, size_t n);
#endif /* __SDCC */
/* 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
#ifdef RESOLV_CONF_AUTO_REMOVE_TRAILING_DOTS
#define RESOLV_AUTO_REMOVE_TRAILING_DOTS RESOLV_CONF_AUTO_REMOVE_TRAILING_DOTS
#else
#define RESOLV_AUTO_REMOVE_TRAILING_DOTS RESOLV_CONF_SUPPORTS_MDNS
#endif
#ifdef RESOLV_CONF_VERIFY_ANSWER_NAMES
#define RESOLV_VERIFY_ANSWER_NAMES RESOLV_CONF_VERIFY_ANSWER_NAMES
#else
#define RESOLV_VERIFY_ANSWER_NAMES RESOLV_CONF_SUPPORTS_MDNS
#endif
#ifdef RESOLV_CONF_SUPPORTS_RECORD_EXPIRATION
#define RESOLV_SUPPORTS_RECORD_EXPIRATION RESOLV_CONF_SUPPORTS_RECORD_EXPIRATION
#else
#define RESOLV_SUPPORTS_RECORD_EXPIRATION 1
#endif
#if RESOLV_CONF_SUPPORTS_MDNS && !RESOLV_VERIFY_ANSWER_NAMES
#error RESOLV_CONF_SUPPORTS_MDNS cannot be set without RESOLV_CONF_VERIFY_ANSWER_NAMES
#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 NATIVE_DNS_TYPE DNS_TYPE_AAAA /* IPv6 */
#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;
};
/** \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;
uint8_t ipaddr[16];
};
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;
uint16_t id;
uint8_t retries;
uint8_t seqno;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
unsigned long expiration;
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
uip_ipaddr_t ipaddr;
uint8_t err;
uint8_t server;
#if RESOLV_CONF_SUPPORTS_MDNS
int is_mdns:1, is_probe:1;
#endif
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);
/** \internal The DNS question message structure. */
struct dns_question {
uint16_t type;
uint16_t class;
};
#if RESOLV_CONF_SUPPORTS_MDNS
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 =
{ { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfb } };
#include "net/ipv6/uip-ds6.h"
static int mdns_needs_host_announce;
PROCESS(mdns_probe_process, "mDNS probe");
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
/*---------------------------------------------------------------------------*/
#if RESOLV_VERIFY_ANSWER_NAMES || VERBOSE_DEBUG
/** \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 uint8_t
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 uint8_t
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((unsigned int)*name++) != tolower((unsigned int)*queryptr++)) {
return 0;
}
}
n = *queryptr++;
if((n != 0) && (*name++ != '.')) {
return 0;
}
}
if(*name == '.')
++name;
return name[0] == 0;
}
#endif /* RESOLV_VERIFY_ANSWER_NAMES */
/*---------------------------------------------------------------------------*/
/** \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)
{
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_linklocal(&uip_ds6_if.addr_list[i].ipaddr)
#endif
) {
if(!*count) {
queryptr = encode_name(queryptr, resolv_hostname);
} else {
/* Use name compression to refer back to the first name */
*queryptr++ = 0xc0;
*queryptr++ = sizeof(struct dns_hdr);
}
*queryptr++ = (uint8_t) ((NATIVE_DNS_TYPE) >> 8);
*queryptr++ = (uint8_t) ((NATIVE_DNS_TYPE));
*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);
}
}
return queryptr;
}
/*---------------------------------------------------------------------------*/
/** \internal
* Called when we need to announce ourselves
*/
static size_t
mdns_prep_host_announce_packet(void)
{
static const struct {
uint16_t type;
uint16_t class;
uint16_t ttl[2];
uint16_t len;
uint8_t data[8];
} nsec_record = {
UIP_HTONS(DNS_TYPE_NSEC),
UIP_HTONS(DNS_CLASS_IN | 0x8000),
{ 0, UIP_HTONS(120) },
UIP_HTONS(8),
{
0xc0,
sizeof(struct dns_hdr), /* Name compression. Re-using the name of first record. */
0x00,
0x04,
0x00,
0x00,
0x00,
0x08,
}
};
unsigned char *queryptr;
uint8_t total_answers = 0;
/* Be aware that, unless `ARCH_DOESNT_NEED_ALIGNED_STRUCTS` is set,
* writing directly to the uint16_t members of this struct is an error. */
struct dns_hdr *hdr = (struct dns_hdr *)uip_appdata;
/* Zero out the header */
memset((void *)hdr, 0, sizeof(*hdr));
hdr->flags1 |= DNS_FLAG1_RESPONSE | DNS_FLAG1_AUTHORATIVE;
queryptr = (unsigned char *)uip_appdata + 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 {
/* Name compression. Re-using the name of first record. */
*queryptr++ = 0xc0;
*queryptr++ = sizeof(*hdr);
}
memcpy((void *)queryptr, (void *)&nsec_record, sizeof(nsec_record));
queryptr += sizeof(nsec_record);
/* This platform might be picky about alignment. To avoid the possibility
* of doing an unaligned write, we are going to do this manually. */
((uint8_t*)&hdr->numanswers)[1] = total_answers;
((uint8_t*)&hdr->numextrarr)[1] = 1;
return (queryptr - (unsigned char *)uip_appdata);
}
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
/*---------------------------------------------------------------------------*/
static char
try_next_server(struct namemap *namemapptr)
{
#if VERBOSE_DEBUG
printf("server %d\n", namemapptr->server);
#endif
namemapptr->server++;
if(uip_nameserver_get(namemapptr->server) != NULL) {
namemapptr->retries = 0;
return 1;
}
namemapptr->server = 0;
return 0;
}
/*---------------------------------------------------------------------------*/
/** \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 /* RESOLV_CONF_SUPPORTS_MDNS */
if(++namemapptr->retries == RESOLV_CONF_MAX_RETRIES)
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
{
/* Try the next server (if possible) before failing. Otherwise
simply mark the entry as failed. */
if(try_next_server(namemapptr) == 0) {
/* STATE_ERROR basically means "not found". */
namemapptr->state = STATE_ERROR;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
/* Keep the "not found" error valid for 30 seconds */
namemapptr->expiration = clock_seconds() + 30;
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
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 /* RESOLV_CONF_SUPPORTS_MDNS */
} 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 = random_rand();
namemapptr->id = hdr->id;
#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 /* RESOLV_CONF_SUPPORTS_MDNS */
hdr->flags1 = DNS_FLAG1_RD;
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
hdr->numquestions = UIP_HTONS(1);
query = (unsigned 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 /* RESOLV_CONF_SUPPORTS_MDNS */
{
*query++ = (uint8_t) ((NATIVE_DNS_TYPE) >> 8);
*query++ = (uint8_t) ((NATIVE_DNS_TYPE));
}
*query++ = (uint8_t) ((DNS_CLASS_IN) >> 8);
*query++ = (uint8_t) ((DNS_CLASS_IN));
#if RESOLV_CONF_SUPPORTS_MDNS
if(namemapptr->is_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);
}
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 %s for \"%s\".\n", i,
namemapptr->is_probe?"probe":"request",namemapptr->name);
} else {
uip_udp_packet_sendto(resolv_conn, uip_appdata,
(query - (uint8_t *) uip_appdata),
(const uip_ipaddr_t *)
uip_nameserver_get(namemapptr->server),
UIP_HTONS(DNS_PORT));
PRINTF("resolver: (i=%d) Sent DNS request for \"%s\".\n", i,
namemapptr->name);
}
#else /* RESOLV_CONF_SUPPORTS_MDNS */
uip_udp_packet_sendto(resolv_conn, uip_appdata,
(query - (uint8_t *) uip_appdata),
uip_nameserver_get(namemapptr->server),
UIP_HTONS(DNS_PORT));
PRINTF("resolver: (i=%d) Sent DNS request for \"%s\".\n", i,
namemapptr->name);
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
break;
}
}
}
/*---------------------------------------------------------------------------*/
/** \internal
* Called when new UDP data arrives.
*/
static void
newdata(void)
{
uint8_t nquestions, nanswers;
int8_t i;
register struct namemap *namemapptr = NULL;
struct dns_answer *ans;
register struct dns_hdr const *hdr = (struct dns_hdr *)uip_appdata;
unsigned char *queryptr = (unsigned char *)hdr + sizeof(*hdr);
const uint8_t is_request = ((hdr->flags1 & ~1) == 0) && (hdr->flags2 == 0);
/* 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);
queryptr = (unsigned char *)hdr + sizeof(*hdr);
i = 0;
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));
if(is_request && (nquestions == 0)) {
/* Skip requests with no questions. */
DEBUG_PRINTF("resolver: Skipping request with no questions.\n");
return;
}
/** QUESTION HANDLING SECTION ************************************************/
for(; nquestions > 0;
queryptr = skip_name(queryptr) + sizeof(struct dns_question),
--nquestions
) {
#if RESOLV_CONF_SUPPORTS_MDNS
if(!is_request) {
/* If this isn't a request, we don't need to bother
* looking at the individual questions. For the most
* part, this loop to just used to skip past them.
*/
continue;
}
{
struct dns_question *question = (struct dns_question *)skip_name(queryptr);
#if !ARCH_DOESNT_NEED_ALIGNED_STRUCTS
static struct dns_question aligned;
memcpy(&aligned, question, sizeof(aligned));
question = &aligned;
#endif /* !ARCH_DOESNT_NEED_ALIGNED_STRUCTS */
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(NATIVE_DNS_TYPE)))) {
/* 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_IP_BUF->srcipaddr,
UIP_UDP_BUF->srcport);
}
return;
} else {
uint8_t nauthrr;
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);
}
}
}
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
}
/** ANSWER HANDLING SECTION **************************************************/
if(nanswers == 0) {
/* Skip responses with no 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 */
{
for(i = 0; i < RESOLV_ENTRIES; ++i) {
namemapptr = &names[i];
if(namemapptr->state == STATE_ASKING &&
namemapptr->id == hdr->id) {
break;
}
}
if(i >= RESOLV_ENTRIES || i < 0 || namemapptr->state != STATE_ASKING) {
PRINTF("resolver: DNS response has bad ID (%04X) \n", uip_ntohs(hdr->id));
return;
}
PRINTF("resolver: Incoming response for \"%s\".\n", namemapptr->name);
/* We'll change this to DONE when we find the record. */
namemapptr->state = STATE_ERROR;
namemapptr->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
/* If we remain in the error state, keep it cached for 30 seconds. */
namemapptr->expiration = clock_seconds() + 30;
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
/* Check for error. If so, call callback to inform. */
if(namemapptr->err != 0) {
namemapptr->state = STATE_ERROR;
resolv_found(namemapptr->name, NULL);
return;
}
}
i = 0;
/* Answer parsing loop */
while(nanswers > 0) {
ans = (struct dns_answer *)skip_name(queryptr);
#if !ARCH_DOESNT_NEED_ALIGNED_STRUCTS
{
static struct dns_answer aligned;
memcpy(&aligned, ans, sizeof(aligned));
ans = &aligned;
}
#endif /* !ARCH_DOESNT_NEED_ALIGNED_STRUCTS */
#if VERBOSE_DEBUG
char debug_name[40];
decode_name(queryptr, debug_name, uip_appdata);
DEBUG_PRINTF("resolver: Answer %d: \"%s\", type %d, class %d, ttl %d, length %d\n",
++i, 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 /* VERBOSE_DEBUG */
/* 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(ans->type != UIP_HTONS(NATIVE_DNS_TYPE)) {
goto skip_to_next_answer;
}
#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)
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
|| (namemapptr->state == STATE_DONE && clock_seconds() > namemapptr->expiration)
#endif /* RESOLV_SUPPORTS_RECORD_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 /* RESOLV_CONF_SUPPORTS_MDNS */
{
/* This will force us to stop even if there are more answers. */
nanswers = 1;
}
/* This is disabled for now, so that we don't fail on CNAME records.
#if RESOLV_VERIFY_ANSWER_NAMES
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;
}
#endif
*/
DEBUG_PRINTF("resolver: Answer for \"%s\" is usable.\n", namemapptr->name);
namemapptr->state = STATE_DONE;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
namemapptr->expiration = (uint32_t) uip_ntohs(ans->ttl[0]) << 16 |
(uint32_t) uip_ntohs(ans->ttl[1]);
namemapptr->expiration += clock_seconds();
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
uip_ipaddr_copy(&namemapptr->ipaddr, (uip_ipaddr_t *) ans->ipaddr);
resolv_found(namemapptr->name, &namemapptr->ipaddr);
break;
skip_to_next_answer:
queryptr = (unsigned char *)skip_name(queryptr) + 10 + uip_htons(ans->len);
--nanswers;
}
/* Got to this point there's no answer, try next nameserver if available
since this one doesn't know the answer */
#if RESOLV_CONF_SUPPORTS_MDNS
if(nanswers == 0 && UIP_UDP_BUF->srcport != UIP_HTONS(MDNS_PORT)
&& hdr->id != 0)
#else
if(nanswers == 0)
#endif
{
if(try_next_server(namemapptr)) {
namemapptr->state = STATE_ASKING;
process_post(&resolv_process, PROCESS_EVENT_TIMER, NULL);
}
}
}
/*---------------------------------------------------------------------------*/
#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 - strlen(resolv_hostname));
}
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);
#if RESOLV_CONF_SUPPORTS_MDNS
PRINTF("resolver: Supports MDNS.\n");
uip_udp_bind(resolv_conn, UIP_HTONS(MDNS_PORT));
uip_ds6_maddr_add(&resolv_mdns_addr);
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 /* RESOLV_CONF_SUPPORTS_MDNS */
{
check_entries();
}
}
}
}
#if RESOLV_CONF_SUPPORTS_MDNS
if(mdns_needs_host_announce) {
tcpip_poll_udp(resolv_conn);
}
#endif /* RESOLV_CONF_SUPPORTS_MDNS */
}
PROCESS_END();
}
/*---------------------------------------------------------------------------*/
static void
init(void)
{
static uint8_t initialized = 0;
if(!initialized) {
process_start(&resolv_process, NULL);
initialized = 1;
}
}
/*---------------------------------------------------------------------------*/
#if RESOLV_AUTO_REMOVE_TRAILING_DOTS
static const char *
remove_trailing_dots(const char *name) {
static char dns_name_without_dots[RESOLV_CONF_MAX_DOMAIN_NAME_SIZE + 1];
size_t len = strlen(name);
if(len && name[len - 1] == '.') {
strncpy(dns_name_without_dots, name, RESOLV_CONF_MAX_DOMAIN_NAME_SIZE);
while(len && (dns_name_without_dots[len - 1] == '.')) {
dns_name_without_dots[--len] = 0;
}
name = dns_name_without_dots;
}
return name;
}
#else /* RESOLV_AUTO_REMOVE_TRAILING_DOTS */
#define remove_trailing_dots(x) (x)
#endif /* RESOLV_AUTO_REMOVE_TRAILING_DOTS */
/*---------------------------------------------------------------------------*/
/**
* 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)
{
uint8_t i;
uint8_t lseq, lseqi;
register struct namemap *nameptr = 0;
init();
lseq = lseqi = 0;
/* Remove trailing dots, if present. */
name = remove_trailing_dots(name);
for(i = 0; i < RESOLV_ENTRIES; ++i) {
nameptr = &names[i];
if(0 == strcasecmp(nameptr->name, name)) {
break;
}
if((nameptr->state == STATE_UNUSED)
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
|| (nameptr->state == STATE_DONE && clock_seconds() > nameptr->expiration)
#endif /* RESOLV_SUPPORTS_RECORD_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) - 1);
nameptr->state = STATE_NEW;
nameptr->seqno = seqno;
++seqno;
#if RESOLV_CONF_SUPPORTS_MDNS
{
size_t name_len = strlen(name);
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 /* RESOLV_CONF_SUPPORTS_MDNS */
/* 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;
uint8_t i;
struct namemap *nameptr;
/* Remove trailing dots, if present. */
name = remove_trailing_dots(name);
#if UIP_CONF_LOOPBACK_INTERFACE
if(strcmp(name, "localhost")) {
static uip_ipaddr_t loopback =
{ { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } };
if(ipaddr) {
*ipaddr = &loopback;
}
ret = RESOLV_STATUS_CACHED;
}
#endif /* UIP_CONF_LOOPBACK_INTERFACE */
/* 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:
ret = RESOLV_STATUS_CACHED;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
if(clock_seconds() > nameptr->expiration) {
ret = RESOLV_STATUS_EXPIRED;
}
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
break;
case STATE_NEW:
case STATE_ASKING:
ret = RESOLV_STATUS_RESOLVING;
break;
/* Almost certainly a not-found error from server */
case STATE_ERROR:
ret = RESOLV_STATUS_NOT_FOUND;
#if RESOLV_SUPPORTS_RECORD_EXPIRATION
if(clock_seconds() > nameptr->expiration) {
ret = RESOLV_STATUS_UNCACHED;
}
#endif /* RESOLV_SUPPORTS_RECORD_EXPIRATION */
break;
}
if(ipaddr) {
*ipaddr = &nameptr->ipaddr;
}
/* Break out of for loop. */
break;
}
}
#if VERBOSE_DEBUG
switch (ret) {
case RESOLV_STATUS_CACHED:
if(ipaddr) {
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 /* VERBOSE_DEBUG */
return ret;
}
/*---------------------------------------------------------------------------*/
/** \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
&& !uip_ds6_is_my_addr(ipaddr)
) {
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) - 1); /* -1 in order to fit the terminating null byte. */
}
/* Re-add the .local suffix */
strncat(resolv_hostname, ".local", RESOLV_CONF_MAX_DOMAIN_NAME_SIZE - strlen(resolv_hostname));
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 /* RESOLV_CONF_SUPPORTS_MDNS */
#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 /* VERBOSE_DEBUG */
process_post(PROCESS_BROADCAST, resolv_event_found, name);
}
/*---------------------------------------------------------------------------*/
#endif /* UIP_UDP */
/** @} */
/** @} */
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