/****************************************************************************
* libc/netdb/lib_dnsclient.c
* DNS host name to IP address resolver.
*
* The uIP DNS resolver functions are used to lookup a hostname and
* map it to a numerical IP address.
*
* Copyright (C) 2007, 2009, 2012, 2014-2015 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Based heavily on portions of uIP:
*
* Author: Adam Dunkels <adam@dunkels.com>
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <semaphore.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include <assert.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <nuttx/net/dns.h>
#include "netdb/lib_dns.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* The maximum number of retries when asking for a name */
#define MAX_RETRIES 8
/* Buffer sizes */
#define SEND_BUFFER_SIZE 64
#define RECV_BUFFER_SIZE CONFIG_NETDB_DNSCLIENT_MAXRESPONSE
/* Use clock monotonic, if possible */
#ifdef CONFIG_CLOCK_MONOTONIC
# define DNS_CLOCK CLOCK_MONOTONIC
#else
# define DNS_CLOCK CLOCK_REALTIME
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* This describes either an IPv4 or IPv6 address. It is essentially a named
* alternative to sockaddr_storage.
*/
union dns_server_u
{
struct sockaddr addr; /* Common address representation */
#ifdef CONFIG_NET_IPv4
struct sockaddr_in ipv4; /* IPv4 address */
#endif
#ifdef CONFIG_NET_IPv6
struct sockaddr_in6 ipv6; /* IPv6 address */
#endif
};
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* This described one entry in the cache of resolved hostnames */
struct dns_cache_s
{
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
time_t ctime; /* Creation time */
#endif
char name[CONFIG_NETDB_DNSCLIENT_NAMESIZE];
union dns_server_u addr; /* Resolved address */
};
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static sem_t g_dns_sem; /* Protects g_seqno and DNS cache */
static bool g_dns_initialized; /* DNS data structures initialized */
static bool g_dns_address; /* We have the address of the DNS server */
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
static uint8_t g_dns_head; /* Head of the circular, DNS resolver cache */
static uint8_t g_dns_tail; /* Tail of the circular, DNS resolver cache */
#endif
static uint8_t g_seqno; /* Sequence number of the next request */
/* The DNS server address */
static union dns_server_u g_dns_server;
#ifdef CONFIG_NETDB_DNSSERVER_IPv6
/* This is the default IPv6 DNS server address */
static const uint16_t g_ipv6_hostaddr[8] =
{
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_1),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_2),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_3),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_4),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_5),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_6),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_7),
HTONS(CONFIG_NETDB_DNSSERVER_IPv6ADDR_8)
};
#endif
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* This is the DNS resolver cache */
static struct dns_cache_s g_dns_cache[CONFIG_NETDB_DNSCLIENT_ENTRIES];
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: dns_semtake
*
* Description:
* Take the DNS semaphore, ignoring errors do to the receipt of signals.
*
****************************************************************************/
static void dns_semtake(void)
{
int errcode = 0;
int ret;
do
{
ret = sem_wait(&g_dns_sem);
if (ret < 0)
{
errcode = get_errno();
DEBUGASSERT(errcode == EINTR);
}
}
while (ret < 0 && errcode == EINTR);
}
/****************************************************************************
* Name: dns_semgive
*
* Description:
* Release the DNS semaphore
*
****************************************************************************/
#define dns_semgive() sem_post(&g_dns_sem)
/****************************************************************************
* Name: dns_initialize
*
* Description:
* Make sure that the DNS client has been properly initialized for use.
*
****************************************************************************/
static bool dns_initialize(void)
{
/* Have DNS data structures been initialized? */
if (!g_dns_initialized)
{
sem_init(&g_dns_sem, 0, 1);
g_dns_initialized = true;
}
/* Has the DNS server IP address been assigned? */
if (!g_dns_address)
{
#if defined(CONFIG_NETDB_DNSSERVER_IPv4)
struct sockaddr_in addr4;
int ret;
/* No, configure the default IPv4 DNS server address */
addr4.sin_family = AF_INET;
addr4.sin_port = DNS_DEFAULT_PORT;
addr4.sin_addr.s_addr = HTONL(CONFIG_NETDB_DNSSERVER_IPv4ADDR);
ret = dns_setserver((FAR struct sockaddr *)&addr4,
sizeof(struct sockaddr_in));
if (ret < 0)
{
return false;
}
#elif defined(CONFIG_NETDB_DNSSERVER_IPv6)
struct sockaddr_in6 addr6;
int ret;
/* No, configure the default IPv6 DNS server address */
addr6.sin6_family = AF_INET6;
addr6.sin6_port = DNS_DEFAULT_PORT;
memcpy(addr6.sin6_addr.s6_addr, g_ipv6_hostaddr, 16);
ret = dns_setserver((FAR struct sockaddr *)&addr6,
sizeof(struct sockaddr_in6));
if (ret < 0)
{
return false;
}
#else
/* No, then we are not ready to perform DNS queries */
return false;
#endif
}
return true;
}
/****************************************************************************
* Name: dns_save_answer
*
* Description:
* Same the last resolved hostname in the DNS cache
*
* Input Parameters:
* hostname - The hostname string to be cached.
* addr - The IP address associated with the hostname
* addrlen - The size of the of the IP address.
*
* Returned Value:
* None
*
****************************************************************************/
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
static void dns_save_answer(FAR const char *hostname,
FAR const struct sockaddr *addr,
socklen_t addrlen)
{
FAR struct dns_cache_s *entry;
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
struct timespec now;
#endif
int next;
int ndx;
/* Get exclusive access to the DNS cache */
dns_semtake();
/* Get the index to the new head of the list */
ndx = g_dns_head;
next = ndx + 1;
if (next >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
{
next = 0;
}
/* If the next head pointer would match the tail index, then increment
* the tail index, discarding the oldest mapping in the cache.
*/
if (next == g_dns_tail)
{
int tmp = g_dns_tail + 1;
if (tmp >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
{
tmp = 0;
}
g_dns_tail = tmp;
}
/* Save the answer in the cache */
entry = &g_dns_cache[ndx];
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
/* Get the current time, using CLOCK_MONOTONIC if possible */
(void)clock_settime(DNS_CLOCK, &now);
entry->ctime = (time_t)now.tv_sec;
#endif
strncpy(entry->name, hostname, CONFIG_NETDB_DNSCLIENT_NAMESIZE);
memcpy(&entry->addr.addr, addr, addrlen);
/* Save the updated head index */
g_dns_head = next;
dns_semgive();
}
#endif
/****************************************************************************
* Name: dns_parse_name
*
* Description:
* Walk through a compact encoded DNS name and return the end of it.
*
****************************************************************************/
static FAR uint8_t *dns_parse_name(FAR uint8_t *query)
{
uint8_t n;
do
{
n = *query++;
while (n > 0)
{
++query;
--n;
}
}
while (*query != 0);
return query + 1;
}
/****************************************************************************
* Name: dns_send_query
*
* Description:
* 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 int dns_send_query(int sd, FAR const char *name,
FAR union dns_server_u *uaddr, uint16_t rectype)
{
register FAR struct dns_header_s *hdr;
FAR uint8_t *dest;
FAR uint8_t *nptr;
FAR const char *src;
uint8_t buffer[SEND_BUFFER_SIZE];
uint8_t seqno;
socklen_t addrlen;
int errcode;
int ret;
int n;
/* Increment the sequence number */
dns_semtake();
seqno = g_seqno++;
dns_semgive();
/* Initialize the request header */
hdr = (FAR struct dns_header_s *)buffer;
memset(hdr, 0, sizeof(struct dns_header_s));
hdr->id = htons(seqno);
hdr->flags1 = DNS_FLAG1_RD;
hdr->numquestions = HTONS(1);
dest = buffer + 12;
/* Convert hostname into suitable query format. */
src = name - 1;
do
{
/* Copy the name string */
src++;
nptr = dest++;
for (n = 0; *src != '.' && *src != 0; src++)
{
*dest++ = *(uint8_t *)src;
n++;
}
/* Pre-pend the name length */
*nptr = n;
}
while (*src != '\0');
/* Add NUL termination, DNS record type, and DNS class */
*dest++ = '\0'; /* NUL termination */
*dest++ = (rectype >> 8); /* DNS record type (big endian) */
*dest++ = (rectype & 0xff);
*dest++ = (DNS_CLASS_IN >> 8); /* DNS record class (big endian) */
*dest++ = (DNS_CLASS_IN & 0xff);
/* Send the request */
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (uaddr->addr.sa_family == AF_INET)
#endif
{
addrlen = sizeof(struct sockaddr_in);
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
addrlen = sizeof(struct sockaddr_in6);
}
#endif
ret = sendto(sd, buffer, dest - buffer, 0, &uaddr->addr, addrlen);
/* Return the negated errno value on sendto failure */
if (ret < 0)
{
errcode = get_errno();
ndbg("ERROR: sendto failed: %d\n", errcode);
return -errcode;
}
return OK;
}
/****************************************************************************
* Name: dns_recv_response
*
* Description:
* Called when new UDP data arrives
*
****************************************************************************/
static int dns_recv_response(int sd, FAR struct sockaddr *addr,
FAR socklen_t *addrlen)
{
FAR uint8_t *nameptr;
char buffer[RECV_BUFFER_SIZE];
FAR struct dns_answer_s *ans;
FAR struct dns_header_s *hdr;
#if 0 /* Not used */
uint8_t nquestions;
#endif
uint8_t nanswers;
int errcode;
int ret;
/* Receive the response */
ret = recv(sd, buffer, RECV_BUFFER_SIZE, 0);
if (ret < 0)
{
errcode = get_errno();
ndbg("ERROR: recv failed: %d\n", errcode);
return -errcode;
}
hdr = (FAR struct dns_header_s *)buffer;
nvdbg("ID %d\n", htons(hdr->id));
nvdbg("Query %d\n", hdr->flags1 & DNS_FLAG1_RESPONSE);
nvdbg("Error %d\n", hdr->flags2 & DNS_FLAG2_ERR_MASK);
nvdbg("Num questions %d, answers %d, authrr %d, extrarr %d\n",
htons(hdr->numquestions), htons(hdr->numanswers),
htons(hdr->numauthrr), htons(hdr->numextrarr));
/* Check for error */
if ((hdr->flags2 & DNS_FLAG2_ERR_MASK) != 0)
{
ndbg("ERROR: DNS reported error: flags2=%02x\n", hdr->flags2);
return -EPROTO;
}
/* We only care about the question(s) and the answers. The authrr
* and the extrarr are simply discarded.
*/
#if 0 /* Not used */
nquestions = htons(hdr->numquestions);
#endif
nanswers = htons(hdr->numanswers);
/* Skip the name in the question. TODO: This should really be
* checked against the name in the question, to be sure that they
* match.
*/
#ifdef CONFIG_DEBUG_NET
{
int d = 64;
nameptr = dns_parse_name((uint8_t *)buffer + 12) + 4;
for (; ; )
{
ndbg("%02X %02X %02X %02X %02X %02X %02X %02X \n",
nameptr[0], nameptr[1], nameptr[2], nameptr[3],
nameptr[4], nameptr[5], nameptr[6], nameptr[7]);
nameptr += 8;
d -= 8;
if (d < 0)
{
break;
}
}
}
#endif
nameptr = dns_parse_name((uint8_t *)buffer + 12) + 4;
for (; nanswers > 0; nanswers--)
{
/* 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;
nvdbg("Compressed answer\n");
}
else
{
/* Not compressed name. */
nameptr = dns_parse_name(nameptr);
}
ans = (FAR struct dns_answer_s *)nameptr;
nvdbg("Answer: type=%04x, class=%04x, ttl=%06x, length=%04x \n",
htons(ans->type), htons(ans->class),
(htons(ans->ttl[0]) << 16) | htons(ans->ttl[1]),
htons(ans->len));
/* Check for IPv4/6 address type and Internet class. Others are discarded. */
#ifdef CONFIG_NET_IPv4
if (ans->type == HTONS(DNS_RECTYPE_A) &&
ans->class == HTONS(DNS_CLASS_IN) &&
ans->len == HTONS(4))
{
ans->u.ipv4.s_addr = *(FAR uint32_t *)(nameptr + 10);
nvdbg("IPv4 address: %d.%d.%d.%d\n",
(ans->u.ipv4.s_addr ) & 0xff,
(ans->u.ipv4.s_addr >> 8 ) & 0xff,
(ans->u.ipv4.s_addr >> 16) & 0xff,
(ans->u.ipv4.s_addr >> 24) & 0xff);
if (*addrlen >= sizeof(struct sockaddr_in))
{
FAR struct sockaddr_in *inaddr;
inaddr = (FAR struct sockaddr_in *)addr;
inaddr->sin_family = AF_INET;
inaddr->sin_port = 0;
inaddr->sin_addr.s_addr = ans->u.ipv4.s_addr;
*addrlen = sizeof(struct sockaddr_in);
return OK;
}
else
{
return -ERANGE;
}
}
else
#endif
#ifdef CONFIG_NET_IPv6
if (ans->type == HTONS(DNS_RECTYPE_AAAA) &&
ans->class == HTONS(DNS_CLASS_IN) &&
ans->len == HTONS(16))
{
memcpy(&ans->u.ipv6.s6_addr, nameptr + 10, 16);
nvdbg("IPv6 address: %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
htons(ans->u.ipv6.s6_addr[7]), htons(ans->u.ipv6.s6_addr[6]),
htons(ans->u.ipv6.s6_addr[5]), htons(ans->u.ipv6.s6_addr[4]),
htons(ans->u.ipv6.s6_addr[3]), htons(ans->u.ipv6.s6_addr[2]),
htons(ans->u.ipv6.s6_addr[1]), htons(ans->u.ipv6.s6_addr[0]));
if (*addrlen >= sizeof(struct sockaddr_in6))
{
FAR struct sockaddr_in6 *inaddr;
inaddr = (FAR struct sockaddr_in6 *)addr;
inaddr->sin6_family = AF_INET;
inaddr->sin6_port = 0;
memcpy(inaddr->sin6_addr.s6_addr, ans->u.ipv6.s6_addr, 16);
*addrlen = sizeof(struct sockaddr_in6);
return OK;
}
else
{
return -ERANGE;
}
}
else
#endif
{
nameptr = nameptr + 10 + htons(ans->len);
}
}
return -EADDRNOTAVAIL;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: dns_bind
*
* Description:
* Initialize the DNS resolver and return a socket bound to the DNS name
* server. The name server was previously selected via dns_server().
*
* Input Parameters:
* None
*
* Returned Value:
* On success, the bound, non-negative socket descriptor is returned. A
* negated errno value is returned on any failure.
*
****************************************************************************/
int dns_bind(void)
{
struct timeval tv;
int errcode;
int sd;
int ret;
/* Has the DNS client been properly initialized? */
if (!dns_initialize())
{
ndbg("ERROR: DNS client has not been initialized\n");
return -EDESTADDRREQ;
}
/* Create a new socket */
sd = socket(PF_INET, SOCK_DGRAM, 0);
if (sd < 0)
{
errcode = get_errno();
ndbg("ERROR: socket() failed: %d\n", errcode);
return -errcode;
}
/* Set up a receive timeout */
tv.tv_sec = 30;
tv.tv_usec = 0;
ret = setsockopt(sd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(struct timeval));
if (ret < 0)
{
errcode = get_errno();
ndbg("ERROR: setsockopt() failed: %d\n", errcode);
close(sd);
return -errcode;
}
return sd;
}
/****************************************************************************
* Name: dns_query
*
* Description:
* Using the DNS resolver socket (sd), look up the the 'hostname', and
* return its IP address in 'ipaddr'
*
* Input Parameters:
* sd - The socket descriptor previously initialized by dsn_bind().
* hostname - The hostname string to be resolved.
* addr - The location to return the IP address associated with the
* hostname
* addrlen - On entry, the size of the buffer backing up the 'addr'
* pointer. On return, this location will hold the actual size of
* the returned address.
*
* Returned Value:
* Returns zero (OK) if the query was successful.
*
****************************************************************************/
int dns_query(int sd, FAR const char *hostname, FAR struct sockaddr *addr,
FAR socklen_t *addrlen)
{
#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
int noipv4 = false;
int noipv6 = false;
#endif
int retries;
int ret;
/* Loop while receive timeout errors occur and there are remaining retries */
for (retries = 0; retries < 3; retries++)
{
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
/* If we know that the IPv4 address is not available, then don't try
* again.
*/
if (!noipv4)
#endif
{
/* Send the IPv4 query */
ret = dns_send_query(sd, hostname, &g_dns_server, DNS_RECTYPE_A);
if (ret < 0)
{
ndbg("ERROR: IPv4 dns_send_query failed: %d\n", ret);
return ret;
}
/* Obtain the IPv4 response */
ret = dns_recv_response(sd, addr, addrlen);
if (ret >= 0)
{
/* IPv4 response received successfully */
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* Save the answer in the DNS cache */
dns_save_answer(hostname, addr, *addrlen);
#endif
return OK;
}
/* Handle errors */
ndbg("ERROR: IPv4 dns_recv_response failed: %d\n", ret);
#ifdef CONFIG_NET_IPv6
if (ret != -EADDRNOTAVAIL)
{
/* The IPv4 address is not available. */
noipv4 = true;
if (noipv6)
{
/* Neither address is available */
return ret;
}
}
else
#endif
if (ret != -EAGAIN)
{
/* Some failure other than receive timeout occurred */
return ret;
}
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
/* If we know that the IPv4 address is not available, then don't try
* again.
*/
if (!noipv6)
#endif
{
/* Send the IPv6 query */
ret = dns_send_query(sd, hostname, &g_dns_server,
DNS_RECTYPE_AAAA);
if (ret < 0)
{
ndbg("ERROR: IPv6 dns_send_query failed: %d\n", ret);
return ret;
}
/* Obtain the IPv6 response */
ret = dns_recv_response(sd, addr, addrlen);
if (ret >= 0)
{
/* IPv6 response received successfully */
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* Save the answer in the DNS cache */
dns_save_answer(hostname, addr, *addrlen);
#endif
return OK;
}
/* Handle errors */
ndbg("ERROR: IPv6 dns_recv_response failed: %d\n", ret);
#ifdef CONFIG_NET_IPv4
if (ret != -EADDRNOTAVAIL)
{
/* The IPv6 address is not available. */
noipv6 = true;
if (noipv4)
{
/* Neither address is available */
return ret;
}
}
else
#endif
if (ret != -EAGAIN)
{
/* Some failure other than receive timeout occurred */
return ret;
}
}
#endif
}
return -ETIMEDOUT;
}
/****************************************************************************
* Name: dns_setserver
*
* Description:
* Configure which DNS server to use for queries
*
****************************************************************************/
int dns_setserver(FAR const struct sockaddr *addr, socklen_t addrlen)
{
FAR uint16_t *pport;
size_t copylen;
DEBUGASSERT(addr != NULL);
/* Copy the new server IP address into our private global data structure */
#ifdef CONFIG_NET_IPv4
/* Check for an IPv4 address */
if (addr->sa_family == AF_INET)
{
/* Set up for the IPv4 address copy */
copylen = sizeof(struct sockaddr_in);
pport = &g_dns_server.ipv4.sin_port;
}
else
#endif
#ifdef CONFIG_NET_IPv6
/* Check for an IPv6 address */
if (addr->sa_family == AF_INET6)
{
/* Set up for the IPv6 address copy */
copylen = sizeof(struct sockaddr_in6);
pport = &g_dns_server.ipv6.sin6_port;
}
else
#endif
{
nvdbg("ERROR: Unsupported family: %d\n", addr->sa_family);
return -ENOSYS;
}
/* Copy the IP address */
if (addrlen < copylen)
{
nvdbg("ERROR: Invalid addrlen %ld for family %d\n",
(long)addrlen, addr->sa_family);
return -EINVAL;
}
memcpy(&g_dns_server.addr, addr, copylen);
/* A port number of zero means to use the default DNS server port number */
if (*pport == 0)
{
*pport = HTONS(DNS_DEFAULT_PORT);
}
/* We now have a valid DNS address */
g_dns_address = true;
return OK;
}
/****************************************************************************
* Name: dns_getserver
*
* Description:
* Obtain the currently configured DNS server.
*
****************************************************************************/
int dns_getserver(FAR struct sockaddr *addr, FAR socklen_t *addrlen)
{
socklen_t copylen;
DEBUGASSERT(addr != NULL && addrlen != NULL);
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (g_dns_server.addr.sa_family == AF_INET)
#endif
{
copylen = sizeof(struct sockaddr_in);
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
copylen = sizeof(struct sockaddr_in6);
}
#endif
/* Copy the DNS server address to the caller-provided buffer */
if (copylen > *addrlen)
{
nvdbg("ERROR: addrlen %ld too small for address family %d\n",
(long)addrlen, g_dns_server.addr.sa_family);
return -EINVAL;
}
memcpy(addr, &g_dns_server.addr, copylen);
*addrlen = copylen;
return OK;
}
/****************************************************************************
* Name: dns_find_answer
*
* Description:
* Check if we already have the resolved hostname address in the cache.
*
* Input Parameters:
* hostname - The hostname string to be resolved.
* addr - The location to return the IP address associated with the
* hostname
* addrlen - On entry, the size of the buffer backing up the 'addr'
* pointer. On return, this location will hold the actual size of
* the returned address.
*
* Returned Value:
* If the host name was successfully found in the DNS name resolution
* cache, zero (OK) will be returned. Otherwise, some negated errno
* value will be returned, typically -ENOENT meaning that the hostname
* was not found in the cache.
*
****************************************************************************/
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
int dns_find_answer(FAR const char *hostname, FAR struct sockaddr *addr,
FAR socklen_t *addrlen)
{
FAR struct dns_cache_s *entry;
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
struct timespec now;
uint32_t elapsed;
int ret;
#endif
int next;
int ndx;
/* If DNS not initialized, no need to proceed */
if (!g_dns_initialized)
{
ndbg("ERROR: DNS not initialized yet\n");
return -EAGAIN;
}
/* Get exclusive access to the DNS cache */
dns_semtake();
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
/* Get the current time, using CLOCK_MONOTONIC if possible */
ret = clock_settime(DNS_CLOCK, &now);
#endif
/* REVISIT: This is not thread safe */
for (ndx = g_dns_tail; ndx != g_dns_head; ndx = next)
{
entry = &g_dns_cache[ndx];
/* Advance the index for the next time through the loop, handling
* wrapping to the beginning of the circular buffer.
*/
next = ndx + 1;
if (next >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
{
next = 0;
}
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
/* Check if this entry has expired
* REVISIT: Does not this calculation assume that the sizeof(time_t)
* is equal to the sizeof(uint32_t)?
*/
elapsed = (uint32_t)now.tv_sec - (uint32_t)entry->ctime;
if (ret >= 0 && elapsed > CONFIG_NETDB_DNSCLIENT_LIFESEC)
{
/* This entry has expired. Increment the tail index to exclude
* this entry on future traversals.
*/
g_dns_tail = next;
}
else
#endif
{
/* The entry has not expired, check for a name match. Notice that
* because the names are truncated to CONFIG_NETDB_DNSCLIENT_NAMESIZE,
* this has the possibility of aliasing two names and returning
* the wrong entry from the cache.
*/
if (strncmp(hostname, entry->name, CONFIG_NETDB_DNSCLIENT_NAMESIZE) == 0)
{
socklen_t inlen;
/* We have a match. Return the resolved host address */
#ifdef CONFIG_NET_IPv4
if (entry->addr.addr.sa_family == AF_INET)
#ifdef CONFIG_NET_IPv6
#endif
{
inlen = sizeof(struct sockaddr_in);
}
#endif
#ifdef CONFIG_NET_IPv6
else
#ifdef CONFIG_NET_IPv4
#endif
{
inlen = sizeof(struct sockaddr_in6);
}
#endif
/* Make sure that the address will fit in the caller-provided
* buffer.
*/
if (*addrlen < inlen)
{
ret = -ERANGE;
goto errout_with_sem;
}
/* Return the address information */
memcpy(addr, &entry->addr.addr, inlen);
*addrlen = inlen;
dns_semgive();
return OK;
}
}
}
ret = -ENOENT;
errout_with_sem:
dns_semgive();
return ret;
}
#endif