500 lines
14 KiB
C
500 lines
14 KiB
C
/**
|
|
* \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>
|
|
*
|
|
* This file implements a DNS host name to IP address 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.
|
|
*
|
|
* $Id: resolv.c,v 1.3 2006/08/14 23:37:21 oliverschmidt Exp $
|
|
*
|
|
*/
|
|
|
|
#include "net/tcpip.h"
|
|
#include "net/resolv.h"
|
|
|
|
#include <string.h>
|
|
|
|
#ifndef NULL
|
|
#define NULL (void *)0
|
|
#endif /* NULL */
|
|
|
|
/** \internal The maximum number of retries when asking for a name. */
|
|
#define MAX_RETRIES 8
|
|
|
|
/** \internal The DNS message header. */
|
|
struct dns_hdr {
|
|
u16_t id;
|
|
u8_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
|
|
u16_t numquestions;
|
|
u16_t numanswers;
|
|
u16_t numauthrr;
|
|
u16_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. */
|
|
u16_t type;
|
|
u16_t class;
|
|
u16_t ttl[2];
|
|
u16_t len;
|
|
u16_t ipaddr[2];
|
|
};
|
|
|
|
struct namemap {
|
|
#define STATE_UNUSED 0
|
|
#define STATE_NEW 1
|
|
#define STATE_ASKING 2
|
|
#define STATE_DONE 3
|
|
#define STATE_ERROR 4
|
|
u8_t state;
|
|
u8_t tmr;
|
|
u8_t retries;
|
|
u8_t seqno;
|
|
u8_t err;
|
|
char name[32];
|
|
u16_t ipaddr[2];
|
|
};
|
|
|
|
#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 u8_t seqno;
|
|
|
|
static struct uip_udp_conn *resolv_conn = NULL;
|
|
|
|
process_event_t resolv_event_found;
|
|
|
|
PROCESS(resolv_process, "DNS resolver");
|
|
|
|
enum {
|
|
EVENT_NEW_SERVER=0
|
|
};
|
|
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/** \internal
|
|
* Walk through a compact encoded DNS name and return the end of it.
|
|
*
|
|
* \return The end of the name.
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
static unsigned char *
|
|
parse_name(unsigned char *query)
|
|
{
|
|
unsigned char n;
|
|
|
|
do {
|
|
n = *query++;
|
|
|
|
while(n > 0) {
|
|
/* printf("%c", *query);*/
|
|
++query;
|
|
--n;
|
|
};
|
|
/* printf(".");*/
|
|
} while(*query != 0);
|
|
/* printf("\n");*/
|
|
return query + 1;
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/** \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)
|
|
{
|
|
register struct dns_hdr *hdr;
|
|
char *query, *nptr, *nameptr;
|
|
static u8_t i;
|
|
static u8_t n;
|
|
register struct namemap *namemapptr;
|
|
|
|
for(i = 0; i < RESOLV_ENTRIES; ++i) {
|
|
namemapptr = &names[i];
|
|
if(namemapptr->state == STATE_NEW ||
|
|
namemapptr->state == STATE_ASKING) {
|
|
if(namemapptr->state == STATE_ASKING) {
|
|
if(--namemapptr->tmr == 0) {
|
|
if(++namemapptr->retries == MAX_RETRIES) {
|
|
namemapptr->state = STATE_ERROR;
|
|
resolv_found(namemapptr->name, NULL);
|
|
continue;
|
|
}
|
|
namemapptr->tmr = namemapptr->retries;
|
|
} else {
|
|
/* printf("Timer %d\n", namemapptr->tmr);*/
|
|
/* 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 = htons(i);
|
|
hdr->flags1 = DNS_FLAG1_RD;
|
|
hdr->numquestions = HTONS(1);
|
|
query = (char *)uip_appdata + 12;
|
|
nameptr = namemapptr->name;
|
|
--nameptr;
|
|
/* Convert hostname into suitable query format. */
|
|
do {
|
|
++nameptr;
|
|
nptr = query;
|
|
++query;
|
|
for(n = 0; *nameptr != '.' && *nameptr != 0; ++nameptr) {
|
|
*query = *nameptr;
|
|
++query;
|
|
++n;
|
|
}
|
|
*nptr = n;
|
|
} while(*nameptr != 0);
|
|
{
|
|
static unsigned char endquery[] =
|
|
{0,0,1,0,1};
|
|
memcpy(query, endquery, 5);
|
|
}
|
|
uip_udp_send((unsigned char)(query + 5 - (char *)uip_appdata));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/** \internal
|
|
* Called when new UDP data arrives.
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
static void
|
|
newdata(void)
|
|
{
|
|
char *nameptr;
|
|
struct dns_answer *ans;
|
|
struct dns_hdr *hdr;
|
|
static u8_t nquestions, nanswers;
|
|
static u8_t i;
|
|
register struct namemap *namemapptr;
|
|
|
|
hdr = (struct dns_hdr *)uip_appdata;
|
|
/* printf("ID %d\n", htons(hdr->id));
|
|
printf("Query %d\n", hdr->flags1 & DNS_FLAG1_RESPONSE);
|
|
printf("Error %d\n", hdr->flags2 & DNS_FLAG2_ERR_MASK);
|
|
printf("Num questions %d, answers %d, authrr %d, extrarr %d\n",
|
|
htons(hdr->numquestions),
|
|
htons(hdr->numanswers),
|
|
htons(hdr->numauthrr),
|
|
htons(hdr->numextrarr));
|
|
*/
|
|
|
|
/* The ID in the DNS header should be our entry into the name
|
|
table. */
|
|
i = (u8_t)htons(hdr->id);
|
|
namemapptr = &names[i];
|
|
if(i < RESOLV_ENTRIES &&
|
|
namemapptr->state == STATE_ASKING) {
|
|
|
|
/* This entry is now finished. */
|
|
namemapptr->state = STATE_DONE;
|
|
namemapptr->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
|
|
|
|
/* Check for error. If so, call callback to inform. */
|
|
if(namemapptr->err != 0) {
|
|
namemapptr->state = STATE_ERROR;
|
|
resolv_found(namemapptr->name, NULL);
|
|
return;
|
|
}
|
|
|
|
/* We only care about the question(s) and the answers. The authrr
|
|
and the extrarr are simply discarded. */
|
|
nquestions = (u8_t)htons(hdr->numquestions);
|
|
nanswers = (u8_t)htons(hdr->numanswers);
|
|
|
|
/* Skip the name in the question. XXX: This should really be
|
|
checked agains the name in the question, to be sure that they
|
|
match. */
|
|
nameptr = parse_name((char *)uip_appdata + 12) + 4;
|
|
|
|
while(nanswers > 0) {
|
|
/* The first byte in the answer resource record determines if it
|
|
is a compressed record or a normal one. */
|
|
if(*nameptr & 0xc0) {
|
|
/* Compressed name. */
|
|
nameptr +=2;
|
|
/* printf("Compressed anwser\n");*/
|
|
} else {
|
|
/* Not compressed name. */
|
|
nameptr = parse_name((char *)nameptr);
|
|
}
|
|
|
|
ans = (struct dns_answer *)nameptr;
|
|
/* printf("Answer: type %x, class %x, ttl %x, length %x\n",
|
|
htons(ans->type), htons(ans->class), (htons(ans->ttl[0])
|
|
<< 16) | htons(ans->ttl[1]), htons(ans->len));*/
|
|
|
|
/* Check for IP address type and Internet class. Others are
|
|
discarded. */
|
|
if(ans->type == HTONS(1) &&
|
|
ans->class == HTONS(1) &&
|
|
ans->len == HTONS(4)) {
|
|
/* printf("IP address %d.%d.%d.%d\n",
|
|
htons(ans->ipaddr[0]) >> 8,
|
|
htons(ans->ipaddr[0]) & 0xff,
|
|
htons(ans->ipaddr[1]) >> 8,
|
|
htons(ans->ipaddr[1]) & 0xff);*/
|
|
/* XXX: we should really check that this IP address is the one
|
|
we want. */
|
|
namemapptr->ipaddr[0] = ans->ipaddr[0];
|
|
namemapptr->ipaddr[1] = ans->ipaddr[1];
|
|
|
|
resolv_found(namemapptr->name, namemapptr->ipaddr);
|
|
return;
|
|
} else {
|
|
nameptr = nameptr + 10 + htons(ans->len);
|
|
}
|
|
--nanswers;
|
|
}
|
|
}
|
|
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/** \internal
|
|
* The main UDP function.
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
PROCESS_THREAD(resolv_process, ev, data)
|
|
{
|
|
int i;
|
|
|
|
PROCESS_BEGIN();
|
|
|
|
for(i = 0; i < RESOLV_ENTRIES; ++i) {
|
|
names[i].state = STATE_UNUSED;
|
|
}
|
|
resolv_conn = NULL;
|
|
resolv_event_found = process_alloc_event();
|
|
|
|
|
|
while(1) {
|
|
PROCESS_WAIT_EVENT();
|
|
|
|
if(ev == EVENT_NEW_SERVER) {
|
|
if(resolv_conn != NULL) {
|
|
uip_udp_remove(resolv_conn);
|
|
}
|
|
|
|
resolv_conn = udp_new((uip_ipaddr_t *)data, HTONS(53), NULL);
|
|
|
|
} else if(ev == tcpip_event) {
|
|
if(uip_udp_conn->rport == HTONS(53)) {
|
|
if(uip_poll()) {
|
|
check_entries();
|
|
}
|
|
if(uip_newdata()) {
|
|
newdata();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
PROCESS_END();
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/**
|
|
* 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(char *name)
|
|
{
|
|
static u8_t i;
|
|
static u8_t lseq, lseqi;
|
|
register struct namemap *nameptr;
|
|
|
|
lseq = lseqi = 0;
|
|
|
|
for(i = 0; i < RESOLV_ENTRIES; ++i) {
|
|
nameptr = &names[i];
|
|
if(nameptr->state == STATE_UNUSED) {
|
|
break;
|
|
}
|
|
if(seqno - nameptr->seqno > lseq) {
|
|
lseq = seqno - nameptr->seqno;
|
|
lseqi = i;
|
|
}
|
|
}
|
|
|
|
if(i == RESOLV_ENTRIES) {
|
|
i = lseqi;
|
|
nameptr = &names[i];
|
|
}
|
|
|
|
strncpy(nameptr->name, name, sizeof(nameptr->name));
|
|
nameptr->state = STATE_NEW;
|
|
nameptr->seqno = seqno;
|
|
++seqno;
|
|
|
|
if(resolv_conn != NULL) {
|
|
tcpip_poll_udp(resolv_conn);
|
|
}
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/**
|
|
* 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.
|
|
*
|
|
* \return A pointer to a 4-byte representation of the hostname's IP
|
|
* address, or NULL if the hostname was not found in the array of
|
|
* hostnames.
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
u16_t *
|
|
resolv_lookup(char *name)
|
|
{
|
|
static u8_t i;
|
|
struct namemap *nameptr;
|
|
|
|
/* Walk through the list to see if the name is in there. If it is
|
|
not, we return NULL. */
|
|
for(i = 0; i < RESOLV_ENTRIES; ++i) {
|
|
nameptr = &names[i];
|
|
if(nameptr->state == STATE_DONE &&
|
|
strcmp(name, nameptr->name) == 0) {
|
|
return nameptr->ipaddr;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/**
|
|
* 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.
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
u16_t *
|
|
resolv_getserver(void)
|
|
{
|
|
if(resolv_conn == NULL) {
|
|
return NULL;
|
|
}
|
|
return resolv_conn->ripaddr.u16;
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/**
|
|
* 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(u16_t *dnsserver)
|
|
{
|
|
static u16_t server[2];
|
|
uip_ipaddr_copy(server, dnsserver);
|
|
process_post(&resolv_process, EVENT_NEW_SERVER, server);
|
|
|
|
/* if(resolv_conn != NULL) {
|
|
uip_udp_remove(resolv_conn);
|
|
}
|
|
|
|
resolv_conn = udp_new(dnsserver, 53, NULL);*/
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
/** \internal
|
|
* Callback function which is called when a hostname is found.
|
|
*
|
|
*/
|
|
/*-----------------------------------------------------------------------------------*/
|
|
void
|
|
resolv_found(char *name, u16_t *ipaddr)
|
|
{
|
|
process_post(PROCESS_BROADCAST, resolv_event_found, name);
|
|
}
|
|
/*-----------------------------------------------------------------------------------*/
|
|
|
|
/** @} */
|
|
/** @} */
|