mirror of
https://github.com/lwip-tcpip/lwip.git
synced 2024-09-29 15:20:55 +00:00
632 lines
18 KiB
C
632 lines
18 KiB
C
/**
|
|
* @file
|
|
* DNS - host name to IP address resolver.
|
|
*
|
|
*/
|
|
|
|
/**
|
|
|
|
* This file implements a DNS host name to IP address resolver.
|
|
|
|
* Port to lwIP from uIP
|
|
* by Jim Pettinato April 2007
|
|
|
|
* uIP version 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.
|
|
*
|
|
*
|
|
* DNS.C
|
|
*
|
|
* The lwIP DNS resolver functions are used to lookup a host name and
|
|
* map it to a numerical IP address. It maintains a list of resolved
|
|
* hostnames that can be queried with the dns_lookup() function.
|
|
* New hostnames can be resolved using the dns_query() function.
|
|
*
|
|
* The lwIP version of the resolver also adds a non-blocking version of
|
|
* gethostbyname() that will work with a raw API application. This function
|
|
* checks for an IP address string first and converts it if it is valid.
|
|
* gethostbyname() then does a dns_lookup() to see if the name is
|
|
* already in the table. If so, the IP is returned. If not, a query is
|
|
* issued and the function returns with a DNS_QUERY_QUEUED status. The app
|
|
* using the dns client must then go into a waiting state.
|
|
*
|
|
* Once a hostname has been resolved (or found to be non-existent),
|
|
* the resolver code calls a specified callback function (which
|
|
* must be implemented by the module that uses the resolver).
|
|
*/
|
|
|
|
/*-----------------------------------------------------------------------------
|
|
* RFC 1035 - Domain names - implementation and specification
|
|
* RFC 2181 - Clarifications to the DNS Specification
|
|
*----------------------------------------------------------------------------*/
|
|
|
|
/** @todo: define good default values (rfc compliance) */
|
|
/** @todo: secondary server support */
|
|
/** @todo: pbuf chain not yet supported */
|
|
/** @todo: improve answer parsing, more checkings... */
|
|
|
|
/*-----------------------------------------------------------------------------
|
|
* Includes
|
|
*----------------------------------------------------------------------------*/
|
|
|
|
#include "lwip/opt.h"
|
|
|
|
#if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
|
|
|
|
#include "lwip/udp.h"
|
|
#include "lwip/dns.h"
|
|
|
|
#include <string.h>
|
|
|
|
/** DNS server IP address */
|
|
#ifndef DNS_SERVER_ADDRESS
|
|
#define DNS_SERVER_ADDRESS inet_addr("208.67.222.222") /* resolver1.opendns.com */
|
|
#endif
|
|
|
|
/** DNS server port address */
|
|
#ifndef DNS_SERVER_PORT
|
|
#define DNS_SERVER_PORT 53
|
|
#endif
|
|
|
|
/* The maximum number of table entries to maintain locally */
|
|
#ifndef DNS_TABLE_SIZE
|
|
#define DNS_TABLE_SIZE 4
|
|
#endif
|
|
|
|
/* The maximum length of a host name supported in the name table. */
|
|
#ifndef DNS_MAX_NAME_LENGTH
|
|
#define DNS_MAX_NAME_LENGTH 256
|
|
#endif
|
|
|
|
/* The maximum number of retries when asking for a name, before "timeout". */
|
|
#ifndef DNS_MAX_RETRIES
|
|
#define DNS_MAX_RETRIES 8
|
|
#endif
|
|
|
|
/* DNS entry time to live (in DNS_TMR_INTERVAL ticks) */
|
|
#ifndef DNS_TTL_ENTRY
|
|
#define DNS_TTL_ENTRY 60
|
|
#endif
|
|
|
|
/* DNS protocol flags */
|
|
#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
|
|
|
|
/* DNS protocol states */
|
|
#define DNS_STATE_UNUSED 0
|
|
#define DNS_STATE_NEW 1
|
|
#define DNS_STATE_ASKING 2
|
|
#define DNS_STATE_DONE 3
|
|
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/bpstruct.h"
|
|
#endif
|
|
PACK_STRUCT_BEGIN
|
|
/** DNS message header */
|
|
struct dns_hdr {
|
|
u16_t id;
|
|
u8_t flags1;
|
|
u8_t flags2;
|
|
u16_t numquestions;
|
|
u16_t numanswers;
|
|
u16_t numauthrr;
|
|
u16_t numextrarr;
|
|
} PACK_STRUCT_STRUCT;
|
|
PACK_STRUCT_END
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/epstruct.h"
|
|
#endif
|
|
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/bpstruct.h"
|
|
#endif
|
|
PACK_STRUCT_BEGIN
|
|
/** DNS query message structure */
|
|
struct dns_query {
|
|
/* DNS query 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;
|
|
} PACK_STRUCT_STRUCT;
|
|
PACK_STRUCT_END
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/epstruct.h"
|
|
#endif
|
|
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/bpstruct.h"
|
|
#endif
|
|
PACK_STRUCT_BEGIN
|
|
/** 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;
|
|
u32_t ttl;
|
|
u16_t len;
|
|
} PACK_STRUCT_STRUCT;
|
|
PACK_STRUCT_END
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/epstruct.h"
|
|
#endif
|
|
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/bpstruct.h"
|
|
#endif
|
|
PACK_STRUCT_BEGIN
|
|
/** DNS table entry */
|
|
struct dns_table_entry {
|
|
u8_t state;
|
|
u8_t tmr;
|
|
u8_t retries;
|
|
u8_t ttl;
|
|
u8_t seqno;
|
|
u8_t err;
|
|
char name[DNS_MAX_NAME_LENGTH];
|
|
struct ip_addr ipaddr;
|
|
void (* found)(const char *name, struct ip_addr *ipaddr, void *arg); /* pointer to callback on DNS query done */
|
|
void *arg;
|
|
} PACK_STRUCT_STRUCT;
|
|
PACK_STRUCT_END
|
|
#ifdef PACK_STRUCT_USE_INCLUDES
|
|
# include "arch/epstruct.h"
|
|
#endif
|
|
|
|
/* forward declarations */
|
|
static void dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port);
|
|
static void dns_check_entries(void);
|
|
|
|
/*-----------------------------------------------------------------------------
|
|
* Globales
|
|
*----------------------------------------------------------------------------*/
|
|
|
|
/* DNS variables */
|
|
static struct udp_pcb *dns_pcb;
|
|
static struct dns_table_entry dns_table[DNS_TABLE_SIZE];
|
|
static u8_t dns_seqno;
|
|
|
|
/**
|
|
* Initialize the resolver and configure which DNS server to use for queries.
|
|
*
|
|
* param dnsserver A pointer to a 4-byte representation of the IP
|
|
* address of the DNS server to be configured.
|
|
*/
|
|
err_t
|
|
dns_init()
|
|
{
|
|
u8_t i;
|
|
struct ip_addr dnsserver = {DNS_SERVER_ADDRESS};
|
|
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_init: initializing\n"));
|
|
|
|
/* if dns client not yet initialized... */
|
|
if (dns_pcb == NULL) {
|
|
dns_pcb = udp_new();
|
|
|
|
if (dns_pcb != NULL) {
|
|
/* initialize DNS table */
|
|
for (i=0; i<DNS_TABLE_SIZE; ++i) {
|
|
dns_table[i].state = DNS_STATE_UNUSED;
|
|
dns_table[i].found = NULL;
|
|
}
|
|
|
|
/* initialize DNS client */
|
|
udp_bind(dns_pcb, IP_ADDR_ANY, 0);
|
|
udp_recv(dns_pcb, dns_recv, NULL);
|
|
|
|
/* initialize default DNS primary server */
|
|
dns_setserver(0, &dnsserver);
|
|
}
|
|
}
|
|
return ERR_OK;
|
|
}
|
|
|
|
/**
|
|
* Obtain the currently configured DNS server.
|
|
* return unsigned long encoding of the IP address of
|
|
* the currently configured DNS server or NULL if no DNS server has
|
|
* been configured.
|
|
*/
|
|
void
|
|
dns_setserver(u8_t numdns, struct ip_addr *dnsserver)
|
|
{
|
|
LWIP_UNUSED_ARG(numdns);
|
|
if ((dns_pcb != NULL) && (dnsserver != NULL) && (dnsserver->addr !=0 )) {
|
|
udp_connect( dns_pcb, dnsserver, DNS_SERVER_PORT);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Obtain the currently configured DNS server.
|
|
* return unsigned long encoding of the IP address of
|
|
* the currently configured DNS server or NULL if no DNS server has
|
|
* been configured.
|
|
*/
|
|
u32_t
|
|
dns_getserver(u8_t numdns)
|
|
{
|
|
LWIP_UNUSED_ARG(numdns);
|
|
return ((dns_pcb != NULL)?dns_pcb->remote_ip.addr:0);
|
|
}
|
|
|
|
/**
|
|
* The DNS resolver client timer - handle retries and timeouts
|
|
*/
|
|
void
|
|
dns_tmr(void)
|
|
{
|
|
if (dns_pcb != NULL) {
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_tmr: dns_check_entries\n"));
|
|
dns_check_entries();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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 dns_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.
|
|
*/
|
|
u32_t
|
|
dns_lookup(const char *name)
|
|
{
|
|
u8_t i;
|
|
|
|
/* Walk through name list, return entry if found. If not, return NULL. */
|
|
for (i=0; i<DNS_TABLE_SIZE; ++i) {
|
|
if ( (dns_table[i].state==DNS_STATE_DONE) && (strcmp(name, dns_table[i].name)==0) ) {
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_lookup: \"%s\": found = ", name));
|
|
ip_addr_debug_print(DNS_DEBUG, (&(dns_table[i].ipaddr)));
|
|
LWIP_DEBUGF(DNS_DEBUG, ("\n"));
|
|
return dns_table[i].ipaddr.addr;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* dns_parse_name() - walk through a compact encoded DNS name and return the end
|
|
* of the name.
|
|
*/
|
|
static unsigned char *
|
|
dns_parse_name(unsigned char *query)
|
|
{
|
|
unsigned char n;
|
|
|
|
do {
|
|
n = *query++;
|
|
/** @see RFC 1035 - 4.1.4. Message compression */
|
|
if ((n & 0xc0)==0xc0) {
|
|
/* Compressed name */
|
|
break;
|
|
} else {
|
|
/* Not compressed name */
|
|
while(n > 0) {
|
|
++query;
|
|
--n;
|
|
};
|
|
}
|
|
} while(*query != 0);
|
|
|
|
return query + 1;
|
|
}
|
|
|
|
/**
|
|
* dns_send
|
|
*/
|
|
static err_t
|
|
dns_send(const char* name, u8_t id)
|
|
{
|
|
struct dns_hdr *hdr;
|
|
struct dns_query *qry;
|
|
struct pbuf *p;
|
|
char *query, *nptr;
|
|
const char *pHostname;
|
|
u8_t n;
|
|
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_send: \"%s\": request\n", name));
|
|
|
|
/* if here, we have either a new query or a retry on a previous query to process */
|
|
p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dns_hdr)+DNS_MAX_NAME_LENGTH+sizeof(struct dns_query), PBUF_RAM);
|
|
if (p) {
|
|
/* fill dns header */
|
|
hdr = (struct dns_hdr *)p->payload;
|
|
memset(hdr, 0, sizeof(struct dns_hdr));
|
|
hdr->id = htons(id);
|
|
hdr->flags1 = DNS_FLAG1_RD;
|
|
hdr->numquestions = htons(1);
|
|
query = (char *)hdr + sizeof(struct dns_hdr);
|
|
pHostname = name;
|
|
--pHostname;
|
|
|
|
/* convert hostname into suitable query format. */
|
|
do {
|
|
++pHostname;
|
|
nptr = query;
|
|
++query;
|
|
for(n = 0; *pHostname != '.' && *pHostname != 0; ++pHostname) {
|
|
*query = *pHostname;
|
|
++query;
|
|
++n;
|
|
}
|
|
*nptr = n;
|
|
} while(*pHostname != 0);
|
|
*query++='\0';
|
|
|
|
/* fill dns query */
|
|
qry = (struct dns_query *)query;
|
|
qry->type = htons(DNS_RRTYPE_A);
|
|
qry->class = htons(DNS_RRCLASS_IN);
|
|
|
|
/* resize pbuf to the exact dns query */
|
|
pbuf_realloc(p, (query+sizeof(struct dns_query))-((char*)(p->payload)));
|
|
|
|
/* send dns packet */
|
|
udp_send(dns_pcb, p);
|
|
|
|
/* free pbuf */
|
|
pbuf_free(p);
|
|
|
|
return ERR_OK;
|
|
}
|
|
|
|
return ERR_BUF;
|
|
}
|
|
|
|
/**
|
|
* dns_check_entries() - 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
|
|
dns_check_entries(void)
|
|
{
|
|
u8_t i;
|
|
struct dns_table_entry *pEntry;
|
|
|
|
for (i = 0; i < DNS_TABLE_SIZE; ++i) {
|
|
pEntry = &dns_table[i];
|
|
switch(pEntry->state) {
|
|
|
|
case DNS_STATE_NEW:
|
|
case DNS_STATE_ASKING: {
|
|
if (pEntry->state == DNS_STATE_ASKING) {
|
|
if (--pEntry->tmr == 0) {
|
|
if (++pEntry->retries == DNS_MAX_RETRIES) {
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entries: \"%s\": timeout\n", pEntry->name));
|
|
/* call specified callback function if provided */
|
|
if (pEntry->found)
|
|
(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
|
|
/* flush this entry */
|
|
pEntry->state = DNS_STATE_UNUSED;
|
|
pEntry->found = NULL;
|
|
continue;
|
|
}
|
|
/* wait longer for the next retry */
|
|
pEntry->tmr = pEntry->retries;
|
|
} else {
|
|
/* Its timer has not run out, so we move on to next entry. */
|
|
continue;
|
|
}
|
|
} else {
|
|
pEntry->state = DNS_STATE_ASKING;
|
|
pEntry->tmr = 1;
|
|
pEntry->retries = 0;
|
|
}
|
|
/* send DNS packet for this entry */
|
|
dns_send(pEntry->name, i);
|
|
break;
|
|
}
|
|
|
|
case DNS_STATE_DONE: {
|
|
/* if the time to live is nul */
|
|
if (--pEntry->ttl == 0) {
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entries: \"%s\": flush\n", pEntry->name));
|
|
/* flush this entry */
|
|
pEntry->state = DNS_STATE_UNUSED;
|
|
pEntry->found = NULL;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Callback for DNS responses
|
|
*/
|
|
static void
|
|
dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port)
|
|
{
|
|
u8_t i;
|
|
char *pHostname;
|
|
struct dns_hdr *hdr;
|
|
struct dns_answer *ans;
|
|
struct dns_table_entry *pEntry;
|
|
u8_t nquestions, nanswers;
|
|
|
|
LWIP_ASSERT("dns_recv: pbuf chain not yet supported", (p->next==NULL));
|
|
|
|
hdr = (struct dns_hdr *)p->payload;
|
|
|
|
/** @todo: check RFC1035 - 7.3. Processing responses */
|
|
|
|
/* The ID in the DNS header should be our entry into the name table. */
|
|
i = htons(hdr->id);
|
|
pEntry = &dns_table[i];
|
|
if( (i < DNS_TABLE_SIZE) && (pEntry->state == DNS_STATE_ASKING) ) {
|
|
/* This entry is now completed. */
|
|
pEntry->state = DNS_STATE_DONE;
|
|
pEntry->ttl = DNS_TTL_ENTRY;
|
|
pEntry->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
|
|
|
|
/* We only care about the question(s) and the answers. The authrr
|
|
and the extrarr are simply discarded. */
|
|
nquestions = htons(hdr->numquestions);
|
|
nanswers = htons(hdr->numanswers);
|
|
|
|
/* Check for error. If so, call callback to inform. */
|
|
if (((hdr->flags1 & DNS_FLAG1_RESPONSE)==0) ||(pEntry->err != 0) || (nquestions != 1)) {
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in flags\n", pEntry->name));
|
|
/* call specified callback function if provided */
|
|
if (pEntry->found)
|
|
(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
|
|
/* flush this entry */
|
|
pEntry->state = DNS_STATE_UNUSED;
|
|
pEntry->found = NULL;
|
|
return;
|
|
}
|
|
|
|
/* Skip the name in the "question" part. This should really be checked
|
|
agains the name in the question, to be sure that they match. */
|
|
pHostname = (char *) dns_parse_name((unsigned char *)p->payload + sizeof(struct dns_hdr)) + sizeof(struct dns_query);
|
|
|
|
while(nanswers > 0) {
|
|
/* skip answer resource record's host name */
|
|
pHostname = (char *) dns_parse_name((unsigned char *)pHostname);
|
|
|
|
/* Check for IP address type and Internet class. Others are discarded. */
|
|
ans = (struct dns_answer *)pHostname;
|
|
if((ntohs(ans->type) == DNS_RRTYPE_A) && (ntohs(ans->class) == DNS_RRCLASS_IN) && (ntohs(ans->len) == sizeof(struct ip_addr)) ) {
|
|
/* read the IP address after answer resource record's header */
|
|
pEntry->ipaddr = (*((struct ip_addr*)(ans+1)));
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", pEntry->name));
|
|
ip_addr_debug_print(DNS_DEBUG, (&(pEntry->ipaddr)));
|
|
LWIP_DEBUGF(DNS_DEBUG, ("\n"));
|
|
/* call specified callback function if provided */
|
|
if (pEntry->found)
|
|
(*pEntry->found)(pEntry->name, &pEntry->ipaddr, pEntry->arg);
|
|
return;
|
|
} else {
|
|
pHostname = pHostname + sizeof(struct dns_answer) + htons(ans->len);
|
|
}
|
|
--nanswers;
|
|
}
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in response\n", pEntry->name));
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Queues a name so that a question for the name will be sent out.
|
|
* param name - The hostname that is to be queried.
|
|
*/
|
|
static void
|
|
dns_query(const char *name, void (*found)(const char *name, struct ip_addr *addr, void *arg), void *arg)
|
|
{
|
|
u8_t i;
|
|
u8_t lseq, lseqi;
|
|
struct dns_table_entry *pEntry;
|
|
|
|
/* search an unused entry, or the oldest one */
|
|
lseq = lseqi = 0;
|
|
for (i = 0; i < DNS_TABLE_SIZE; ++i) {
|
|
pEntry = &dns_table[i];
|
|
/* is it an unused entry ? */
|
|
if (pEntry->state == DNS_STATE_UNUSED)
|
|
break;
|
|
|
|
/* check if this is the oldest entry used */
|
|
if (dns_seqno - pEntry->seqno > lseq) {
|
|
lseq = dns_seqno - pEntry->seqno;
|
|
lseqi = i;
|
|
}
|
|
}
|
|
|
|
/* if we don't have found an unused entry, use the oldest one */
|
|
if (i == DNS_TABLE_SIZE) {
|
|
i = lseqi;
|
|
pEntry = &dns_table[i];
|
|
/* since we replace the previous entry, we "unblock" the caller */
|
|
LWIP_DEBUGF(DNS_DEBUG, ("dns_query: \"%s\": replaced by new entry\n", pEntry->name));
|
|
/* call specified callback function if provided */
|
|
if (pEntry->found)
|
|
(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
|
|
}
|
|
|
|
/* fill the entry */
|
|
strcpy(pEntry->name, name);
|
|
pEntry->found = found;
|
|
pEntry->arg = arg;
|
|
pEntry->state = DNS_STATE_NEW;
|
|
pEntry->seqno = dns_seqno++;
|
|
}
|
|
|
|
/**
|
|
* NON-BLOCKING callback version for use with raw API
|
|
*/
|
|
DNS_RESULT dns_gethostbyname(const char *hostname, struct ip_addr *addr,
|
|
void (*found)(const char *name, struct ip_addr *ipaddr, void *arg),
|
|
void *arg
|
|
)
|
|
{
|
|
/* not initialized or no valid server yet, or invalid addr pointer */
|
|
if ((dns_pcb == NULL) || (addr == NULL))
|
|
return DNS_QUERY_INVALID;
|
|
|
|
/* invalid hostname */
|
|
if ((!hostname) || (!hostname[0]))
|
|
return DNS_QUERY_INVALID;
|
|
|
|
/* invalid hostname length */
|
|
if (strlen(hostname) >= DNS_MAX_NAME_LENGTH)
|
|
return DNS_QUERY_INVALID;
|
|
|
|
/* host name already in octet notation? set ip addr and return COMPLETE */
|
|
if ((addr->addr = inet_addr(hostname)) != INADDR_NONE)
|
|
return DNS_COMPLETE;
|
|
|
|
/* already have this address cached? */
|
|
if ((addr->addr = dns_lookup(hostname)) != 0)
|
|
return DNS_COMPLETE;
|
|
|
|
/* queue query with specified callback */
|
|
dns_query(hostname, found, arg);
|
|
|
|
/* force to send request */
|
|
dns_check_entries();
|
|
|
|
return DNS_QUERY_QUEUED;
|
|
}
|
|
|
|
#endif /* LWIP_DNS */
|