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nuttx-apps/netutils/dnsclient/dns_socket.c

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/****************************************************************************
* apps/netutils/dnsclient/dns_socket.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. It maintains a list of resolved
* hostnames that can be queried. New hostnames can be resolved using the
* dns_whois() function.
*
* Copyright (C) 2007, 2009, 2012, 2014 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 <stdint.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include <assert.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <apps/netutils/dnsclient.h>
#include <apps/netutils/netlib.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef CONFIG_NETUTILS_DNSCLIENT_ENTRIES
# define RESOLV_ENTRIES 4
#else /* CONFIG_NETUTILS_DNSCLIENT_ENTRIES */
# define RESOLV_ENTRIES CONFIG_NETUTILS_DNSCLIENT_ENTRIES
#endif /* CONFIG_NETUTILS_DNSCLIENT_ENTRIES */
#ifndef NULL
# define NULL (void *)0
#endif /* NULL */
/* The maximum number of retries when asking for a name */
#define MAX_RETRIES 8
#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
#define SEND_BUFFER_SIZE 64
#ifdef CONFIG_NETUTILS_DNSCLIENT_MAXRESPONSE
# define RECV_BUFFER_SIZE CONFIG_NETUTILS_DNSCLIENT_MAXRESPONSE
#else
# define RECV_BUFFER_SIZE 96
#endif
#ifdef CONFIG_NET_IPv6
# define ADDRLEN sizeof(struct sockaddr_in6)
#else
# define ADDRLEN sizeof(struct sockaddr_in)
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* The DNS message header */
struct dns_hdr
{
uint16_t id;
uint8_t flags1;
uint8_t flags2;
uint16_t numquestions;
uint16_t numanswers;
uint16_t numauthrr;
uint16_t numextrarr;
};
/* 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;
#ifdef CONFIG_NET_IPv6
struct in6_addr ipaddr;
#else
struct in_addr ipaddr;
#endif
};
struct namemap
{
uint8_t state;
uint8_t tmr;
uint8_t retries;
uint8_t seqno;
uint8_t err;
char name[32];
#ifdef CONFIG_NET_IPv6
struct in6_addr ipaddr;
#else
struct in_addr ipaddr;
#endif
};
/****************************************************************************
* Private Data
****************************************************************************/
static uint8_t g_seqno;
#ifdef CONFIG_NET_IPv6
static struct sockaddr_in6 g_dnsserver;
#else
static struct sockaddr_in g_dnsserver;
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: dns_parse_name
*
* Description:
* Walk through a compact encoded DNS name and return the end of it.
*
****************************************************************************/
static FAR unsigned char *dns_parse_name(FAR unsigned char *query)
{
unsigned char 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.
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
static int dns_send_query(int sockfd, FAR const char *name,
FAR struct sockaddr_in6 *addr)
#else
static int dns_send_query(int sockfd, FAR const char *name,
FAR struct sockaddr_in *addr)
#endif
{
register FAR struct dns_hdr *hdr;
FAR char *query;
FAR char *nptr;
FAR const char *nameptr;
uint8_t seqno = g_seqno++;
static unsigned char endquery[] = {0, 0, 1, 0, 1};
char buffer[SEND_BUFFER_SIZE];
int n;
hdr = (FAR struct dns_hdr*)buffer;
memset(hdr, 0, sizeof(struct dns_hdr));
hdr->id = htons(seqno);
hdr->flags1 = DNS_FLAG1_RD;
hdr->numquestions = HTONS(1);
query = buffer + 12;
/* Convert hostname into suitable query format. */
nameptr = name - 1;
do
{
nameptr++;
nptr = query++;
for (n = 0; *nameptr != '.' && *nameptr != 0; nameptr++)
{
*query++ = *nameptr;
n++;
}
*nptr = n;
}
while (*nameptr != 0);
memcpy(query, endquery, 5);
return sendto(sockfd, buffer, query + 5 - buffer,
0, (struct sockaddr*)addr, ADDRLEN);
}
/****************************************************************************
* Name: dns_recv_response
*
* Description:
* Called when new UDP data arrives
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
# error "Not implemented"
#else
static int dns_recv_response(int sockfd, FAR struct sockaddr_in *addr)
#endif
{
FAR unsigned char *nameptr;
char buffer[RECV_BUFFER_SIZE];
FAR struct dns_answer *ans;
FAR struct dns_hdr *hdr;
#if 0 /* Not used */
uint8_t nquestions;
#endif
uint8_t nanswers;
int ret;
/* Receive the response */
ret = recv(sockfd, buffer, RECV_BUFFER_SIZE, 0);
if (ret < 0)
{
return ret;
}
hdr = (FAR struct dns_hdr *)buffer;
ndbg("ID %d\n", htons(hdr->id));
ndbg("Query %d\n", hdr->flags1 & DNS_FLAG1_RESPONSE);
ndbg("Error %d\n", hdr->flags2 & DNS_FLAG2_ERR_MASK);
ndbg("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 so, call callback to inform */
if ((hdr->flags2 & DNS_FLAG2_ERR_MASK) != 0)
{
return ERROR;
}
/* 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((unsigned char *)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((unsigned char *)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;
ndbg("Compressed answer\n");
}
else
{
/* Not compressed name. */
nameptr = dns_parse_name(nameptr);
}
ans = (struct dns_answer *)nameptr;
ndbg("Answer: type %x, class %x, ttl %x, length %x \n", /* 0x%08X\n", */
htons(ans->type), htons(ans->class),
(htons(ans->ttl[0]) << 16) | htons(ans->ttl[1]),
htons(ans->len) /* , ans->ipaddr.s_addr */);
/* Check for IP address type and Internet class. Others are discarded. */
if (ans->type == HTONS(1) &&
ans->class == HTONS(1) &&
ans->len == HTONS(4))
{
ans->ipaddr.s_addr = *(FAR uint32_t *)(nameptr + 10);
ndbg("IP address %d.%d.%d.%d\n",
(ans->ipaddr.s_addr ) & 0xff,
(ans->ipaddr.s_addr >> 8 ) & 0xff,
(ans->ipaddr.s_addr >> 16 ) & 0xff,
(ans->ipaddr.s_addr >> 24 ) & 0xff);
/* TODO: we should really check that this IP address is the one
* we want.
*/
addr->sin_addr.s_addr = ans->ipaddr.s_addr;
return OK;
}
else
{
nameptr = nameptr + 10 + htons(ans->len);
}
}
return ERROR;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: dns_bind_sock
*
* Description:
* Initialize the DNS resolver using the caller provided socket.
*
****************************************************************************/
int dns_bind_sock(FAR int *sockfd)
{
struct timeval tv;
int ret;
/* If the socket is already open, then close it now */
if (*sockfd >= 0)
{
dns_free_sock(sockfd);
}
/* Create a new socket */
*sockfd = socket(PF_INET, SOCK_DGRAM, 0);
if (*sockfd < 0)
{
ndbg("ERROR: socket() failed: %d\n", errno);
return ERROR;
}
/* Set up a receive timeout */
tv.tv_sec = 30;
tv.tv_usec = 0;
ret = setsockopt(*sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv,
sizeof(struct timeval));
if (ret < 0)
{
ndbg("ERROR: setsockopt() failed: %d\n", errno);
close(*sockfd);
*sockfd = -1;
return ERROR;
}
return OK;
}
/****************************************************************************
* Name: dns_free_sock
*
* Description:
* Release the DNS resolver by closing the socket.
*
****************************************************************************/
int dns_free_sock(FAR int *sockfd)
{
if (*sockfd >= 0)
{
close(*sockfd);
*sockfd = -1;
}
return OK;
}
/****************************************************************************
* Name: dns_query_sock
*
* Description:
* Using the DNS resolver socket (sockfd), look up the the 'hostname', and
* return its IP address in 'ipaddr'
*
* Returned Value:
* Returns zero (OK) if the query was successful.
*
****************************************************************************/
int dns_query_sock(int sockfd, FAR const char *hostname, FAR in_addr_t *ipaddr)
{
#ifdef CONFIG_HAVE_GETHOSTBYNAME
FAR struct hostent *he;
nvdbg("Getting address of %s\n", hostname);
he = gethostbyname(hostname);
if (!he)
{
ndbg("gethostbyname failed: %d\n", h_errno);
return ERROR;
}
nvdbg("Using IP address %04x%04x\n",
(uint16_t)he->h_addr[1], (uint16_t)he->h_addr[0]);
memcpy(ipaddr, he->h_addr, sizeof(in_addr_t));
return OK;
#else
# ifdef CONFIG_NET_IPv6
struct sockaddr_in6 addr;
# else
struct sockaddr_in addr;
# endif
/* First check if the host is an IP address. */
if (!netlib_ipaddrconv(hostname, (uint8_t*)ipaddr))
{
/* 'host' does not point to a valid address string. Try to resolve
* the host name to an IP address.
*/
if (dns_whois_socket(sockfd, hostname, &addr) < 0)
{
/* Needs to set the errno here */
return ERROR;
}
/* Save the host address -- Needs fixed for IPv6 */
*ipaddr = addr.sin_addr.s_addr;
}
return OK;
#endif
}
/****************************************************************************
* Name: dns_setserver
*
* Description:
* Configure which DNS server to use for queries
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
void dns_setserver(FAR const struct in6_addr *dnsserver)
#else
void dns_setserver(FAR const struct in_addr *dnsserver)
#endif
{
g_dnsserver.sin_family = AF_INET;
g_dnsserver.sin_port = HTONS(53);
#ifdef CONFIG_NET_IPv6
memcpy(&g_dnsserver.sin6_addr, dnsserver, ADDRLEN);
#else
g_dnsserver.sin_addr.s_addr = dnsserver->s_addr;
#endif
}
/****************************************************************************
* Name: dns_getserver
*
* Description:
* Obtain the currently configured DNS server.
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
void dns_getserver(FAR struct in6_addr *dnsserver)
#else
void dns_getserver(FAR struct in_addr *dnsserver)
#endif
{
#ifdef CONFIG_NET_IPv6
memcpy(dnsserver, &g_dnsserver.sin6_addr, ADDRLEN);
#else
dnsserver->s_addr = g_dnsserver.sin_addr.s_addr;
#endif
}
/****************************************************************************
* Name: dns_whois_socket
*
* Description:
* Get the binding for 'name' using the DNS server accessed via 'sockfd'
*
****************************************************************************/
#ifdef CONFIG_NET_IPv6
int dns_whois_socket(int sockfd, FAR const char *name,
FAR struct sockaddr_in6 *addr)
#else
int dns_whois_socket(int sockfd, FAR const char *name,
FAR struct sockaddr_in *addr)
#endif
{
int retries;
int ret;
/* Loop while receive timeout errors occur and there are remaining retries */
for (retries = 0; retries < 3; retries++)
{
ret = dns_send_query(sockfd, name, &g_dnsserver);
if (ret < 0)
{
return ERROR;
}
ret = dns_recv_response(sockfd, addr);
if (ret >= 0)
{
/* Response received successfully */
return OK;
}
else if (errno != EAGAIN)
{
/* Some failure other than receive timeout occurred */
return ERROR;
}
}
return ERROR;
}
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