--- /dev/null
+/**
+ * \addtogroup apps
+ * @{
+ */
+
+/**
+ * \defgroup resolv DNS 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 with the resolv_lookup()
+ * function. New hostnames can be resolved using the resolv_query()
+ * function.
+ *
+ * When a hostname has been resolved (or found to be non-existant),
+ * the resolver code calls a callback function called resolv_found()
+ * that must be implemented by the module that uses the resolver.
+ */
+
+/**
+ * \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 1.2 2008/08/13 20:12:50 andrewlxia Exp $
+ *
+ */
+
+#include <uip/resolv.h>
+#include <uip/uip.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;
+ uip_ipaddr_t ipaddr;
+};
+
+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];
+ uip_ipaddr_t ipaddr;
+};
+
+#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;
+
+
+int appcall(void){ //for UIP_APPCALL, referred in uip-conf.h
+
+ return 0;
+}
+
+void uip_log(char *msg) //you should replace this by your own log function
+{
+ //PrintDebug("\nuIP log:");
+ //PrintDebug(msg);
+}
+
+
+/**
+ * Callback function which is called when a hostname is found.
+ *
+ * This function must be implemented by the module that uses the DNS
+ * resolver. It is called when a hostname is found, or when a hostname
+ * was not found.
+ *
+ * \param name A pointer to the name that was looked up. \param
+ * ipaddr A pointer to a 4-byte array containing the IP address of the
+ * hostname, or NULL if the hostname could not be found.
+ */
+void resolv_found(char *name, u16_t *ipaddr){
+
+}
+
+/*---------------------------------------------------------------------------*/
+/** \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 = 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 = htons(hdr->numquestions);
+ nanswers = 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.
+ */
+/*---------------------------------------------------------------------------*/
+void
+resolv_appcall(void)
+{
+ if(uip_udp_conn->rport == HTONS(53)) {
+ if(uip_poll()) {
+ check_entries();
+ }
+ if(uip_newdata()) {
+ newdata();
+ }
+ }
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * 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];
+ }
+
+ /* printf("Using entry %d\n", i);*/
+
+ strcpy(nameptr->name, name);
+ nameptr->state = STATE_NEW;
+ nameptr->seqno = seqno;
+ ++seqno;
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * 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;
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * 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.
+ */
+/*---------------------------------------------------------------------------*/
+void
+resolv_conf(u16_t *dnsserver)
+{
+ if(resolv_conn != NULL) {
+ uip_udp_remove(resolv_conn);
+ }
+
+ resolv_conn = uip_udp_new((uip_ipaddr_t *)dnsserver, HTONS(53));
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * Initalize the resolver.
+ */
+/*---------------------------------------------------------------------------*/
+void
+resolv_init(void)
+{
+ static u8_t i;
+
+ for(i = 0; i < RESOLV_ENTRIES; ++i) {
+ names[i].state = STATE_DONE;
+ }
+
+}
+/*---------------------------------------------------------------------------*/
+
+/** @} */
+/** @} */
