441 lines
11 KiB
C
441 lines
11 KiB
C
/****************************************************************************
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* uip-resolv.c
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* DNS host name to IP address resolver.
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*
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* The uIP DNS resolver functions are used to lookup a hostname and
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* map it to a numerical IP address. It maintains a list of resolved
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* hostnames that can be queried with the resolv_lookup()
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* function. New hostnames can be resolved using the resolv_query()
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* function.
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*
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* When a hostname has been resolved (or found to be non-existant),
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* the resolver code calls a callback function called resolv_found()
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* that must be implemented by the module that uses the resolver.
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*
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* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Based heavily on portions of uIP:
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*
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* Author: Adam Dunkels <adam@dunkels.com>
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* Copyright (c) 2002-2003, Adam Dunkels.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <string.h>
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#include <unistd.h>
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#include <time.h>
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#include <errno.h>
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#include <debug.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <net/uip/resolv.h>
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/****************************************************************************
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* Definitions
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****************************************************************************/
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#ifndef CONFIG_NET_RESOLV_ENTRIES
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#define RESOLV_ENTRIES 4
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#else /* CONFIG_NET_RESOLV_ENTRIES */
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#define RESOLV_ENTRIES CONFIG_NET_RESOLV_ENTRIES
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#endif /* CONFIG_NET_RESOLV_ENTRIES */
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#ifndef NULL
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#define NULL (void *)0
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#endif /* NULL */
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/* The maximum number of retries when asking for a name */
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#define MAX_RETRIES 8
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#define DNS_FLAG1_RESPONSE 0x80
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#define DNS_FLAG1_OPCODE_STATUS 0x10
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#define DNS_FLAG1_OPCODE_INVERSE 0x08
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#define DNS_FLAG1_OPCODE_STANDARD 0x00
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#define DNS_FLAG1_AUTHORATIVE 0x04
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#define DNS_FLAG1_TRUNC 0x02
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#define DNS_FLAG1_RD 0x01
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#define DNS_FLAG2_RA 0x80
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#define DNS_FLAG2_ERR_MASK 0x0f
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#define DNS_FLAG2_ERR_NONE 0x00
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#define DNS_FLAG2_ERR_NAME 0x03
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#define SEND_BUFFER_SIZE 64
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#define RECV_BUFFER_SIZE 64
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#ifdef CONFIG_NET_IPv6
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#define ADDRLEN sizeof(struct sockaddr_in6)
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#else
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#define ADDRLEN sizeof(struct sockaddr_in)
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#endif
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/* The DNS message header */
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struct dns_hdr
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{
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uint16_t id;
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uint8_t flags1, flags2;
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uint16_t numquestions;
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uint16_t numanswers;
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uint16_t numauthrr;
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uint16_t numextrarr;
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};
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/* The DNS answer message structure */
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struct dns_answer
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{
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/* DNS answer record starts with either a domain name or a pointer
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* to a name already present somewhere in the packet.
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*/
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uint16_t type;
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uint16_t class;
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uint16_t ttl[2];
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uint16_t len;
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#ifdef CONFIG_NET_IPv6
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struct in6_addr ipaddr;
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#else
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struct in_addr ipaddr;
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#endif
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};
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struct namemap
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{
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uint8_t state;
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uint8_t tmr;
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uint8_t retries;
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uint8_t seqno;
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uint8_t err;
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char name[32];
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#ifdef CONFIG_NET_IPv6
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struct in6_addr ipaddr;
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#else
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struct in_addr ipaddr;
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#endif
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};
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static uint8_t g_seqno;
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static int g_sockfd = -1;
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#ifdef CONFIG_NET_IPv6
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static struct sockaddr_in6 g_dnsserver;
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#else
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static struct sockaddr_in g_dnsserver;
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#endif
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/* Walk through a compact encoded DNS name and return the end of it. */
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static unsigned char *parse_name(unsigned char *query)
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{
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unsigned char n;
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do
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{
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n = *query++;
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while(n > 0)
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{
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++query;
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--n;
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}
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}
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while(*query != 0);
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return query + 1;
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}
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/* Runs through the list of names to see if there are any that have
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* not yet been queried and, if so, sends out a query.
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*/
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#ifdef CONFIG_NET_IPv6
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static int send_query(const char *name, struct sockaddr_in6 *addr)
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#else
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static int send_query(const char *name, struct sockaddr_in *addr)
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#endif
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{
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register struct dns_hdr *hdr;
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char *query;
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char *nptr;
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const char *nameptr;
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uint8_t seqno = g_seqno++;
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static unsigned char endquery[] = {0, 0, 1, 0, 1};
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char buffer[SEND_BUFFER_SIZE];
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int n;
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hdr = (struct dns_hdr*)buffer;
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memset(hdr, 0, sizeof(struct dns_hdr));
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hdr->id = htons(seqno);
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hdr->flags1 = DNS_FLAG1_RD;
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hdr->numquestions = HTONS(1);
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query = buffer + 12;
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/* Convert hostname into suitable query format. */
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nameptr = name - 1;
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do
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{
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nameptr++;
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nptr = query++;
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for (n = 0; *nameptr != '.' && *nameptr != 0; nameptr++)
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{
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*query++ = *nameptr;
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n++;
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}
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*nptr = n;
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}
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while(*nameptr != 0);
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memcpy(query, endquery, 5);
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return sendto(g_sockfd, buffer, query + 5 - buffer, 0, (struct sockaddr*)addr, ADDRLEN);
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}
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/* Called when new UDP data arrives */
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#ifdef CONFIG_NET_IPv6
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#error "Not implemented"
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#else
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int recv_response(struct sockaddr_in *addr)
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#endif
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{
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unsigned char *nameptr;
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char buffer[RECV_BUFFER_SIZE];
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struct dns_answer *ans;
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struct dns_hdr *hdr;
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uint8_t nquestions;
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uint8_t nanswers;
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int ret;
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/* Receive the response */
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ret = recv(g_sockfd, buffer, RECV_BUFFER_SIZE, 0);
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if (ret < 0)
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{
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return ret;
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}
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hdr = (struct dns_hdr *)buffer;
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dbg( "ID %d\n", htons(hdr->id));
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dbg( "Query %d\n", hdr->flags1 & DNS_FLAG1_RESPONSE);
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dbg( "Error %d\n", hdr->flags2 & DNS_FLAG2_ERR_MASK);
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dbg( "Num questions %d, answers %d, authrr %d, extrarr %d\n",
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htons(hdr->numquestions), htons(hdr->numanswers),
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htons(hdr->numauthrr), htons(hdr->numextrarr));
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/* Check for error. If so, call callback to inform */
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if ((hdr->flags2 & DNS_FLAG2_ERR_MASK) != 0)
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{
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return ERROR;
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}
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/* We only care about the question(s) and the answers. The authrr
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* and the extrarr are simply discarded.
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*/
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nquestions = htons(hdr->numquestions);
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nanswers = htons(hdr->numanswers);
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/* Skip the name in the question. XXX: This should really be
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* checked agains the name in the question, to be sure that they
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* match.
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*/
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nameptr = parse_name((unsigned char *)buffer + 12) + 4;
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for (; nanswers > 0; nanswers--)
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{
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/* The first byte in the answer resource record determines if it
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* is a compressed record or a normal one.
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*/
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if (*nameptr & 0xc0)
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{
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/* Compressed name. */
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nameptr +=2;
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dbg("Compressed anwser\n");
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}
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else
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{
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/* Not compressed name. */
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nameptr = parse_name(nameptr);
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}
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ans = (struct dns_answer *)nameptr;
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dbg("Answer: type %x, class %x, ttl %x, length %x\n",
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htons(ans->type), htons(ans->class), (htons(ans->ttl[0]) << 16) | htons(ans->ttl[1]),
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htons(ans->len));
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/* Check for IP address type and Internet class. Others are discarded. */
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if (ans->type == HTONS(1) && ans->class == HTONS(1) && ans->len == HTONS(4))
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{
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dbg("IP address %d.%d.%d.%d\n",
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(ans->ipaddr.s_addr >> 24 ) & 0xff,
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(ans->ipaddr.s_addr >> 16 ) & 0xff,
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(ans->ipaddr.s_addr >> 8 ) & 0xff,
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(ans->ipaddr.s_addr ) & 0xff);
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/* XXX: we should really check that this IP address is the one
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* we want.
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*/
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addr->sin_addr.s_addr = ans->ipaddr.s_addr;
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return OK;
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}
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else
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{
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nameptr = nameptr + 10 + htons(ans->len);
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}
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}
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return ERROR;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/* Get the binding for name. */
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#ifdef CONFIG_NET_IPv6
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int resolv_query(FAR const char *name, FAR struct sockaddr_in6 *addr)
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#else
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int resolv_query(FAR const char *name, FAR struct sockaddr_in *addr)
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#endif
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{
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int retries;
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int ret;
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/* Loop while receive timeout errors occur and there are remaining retries */
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for (retries = 0; retries < 3; retries++)
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{
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if (send_query(name, addr) < 0)
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{
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return ERROR;
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}
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ret = recv_response(addr);
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if (ret >= 0)
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{
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/* Response received successfully */
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return OK;
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}
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else if (errno != EAGAIN)
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{
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/* Some failure other than receive timeout occurred */
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return ERROR;
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}
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}
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return ERROR;
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}
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/* Obtain the currently configured DNS server. */
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#ifdef CONFIG_NET_IPv6
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void resolv_getserver(struct in6_addr *dnsserver)
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#else
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void resolv_getserver(struct in_addr *dnsserver)
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#endif
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{
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#ifdef CONFIG_NET_IPv6
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memcpy(dnsserver, &g_dnsserver.sin6_addr, ADDRLEN);
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#else
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dnsserver->s_addr = g_dnsserver.sin_addr.s_addr;
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#endif
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}
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/* Configure which DNS server to use for queries */
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#ifdef CONFIG_NET_IPv6
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void resolv_conf(const struct in6_addr *dnsserver)
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#else
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void resolv_conf(const struct in_addr *dnsserver)
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#endif
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{
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g_dnsserver.sin_family = AF_INET;
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g_dnsserver.sin_port = HTONS(53);
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#ifdef CONFIG_NET_IPv6
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memcpy(&g_dnsserver.sin6_addr, dnsserver, ADDRLEN);
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#else
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g_dnsserver.sin_addr.s_addr = dnsserver->s_addr;
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#endif
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}
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/* Initalize the resolver. */
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int resolv_init(void)
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{
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struct timeval tv;
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g_sockfd = socket(PF_INET, SOCK_DGRAM, 0);
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if (g_sockfd < 0)
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{
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return ERROR;
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}
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/* Set up a receive timeout */
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tv.tv_sec = 30;
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tv.tv_usec = 0;
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if (setsockopt(g_sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(struct timeval)) < 0)
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{
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close(g_sockfd);
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g_sockfd = -1;
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return ERROR;
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}
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return OK;
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}
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