dns_demo.c

基于lm3s6965的DNS示例代码,对初学者特别有帮助。

/*----------------------------------------------------------------------------
 *      R T L   T C P N E T   E x a m p l e
 *----------------------------------------------------------------------------
 *      Name:    DNS_DEMO.C
 *      Purpose: Telnet Server demo example
 *      Rev.:    V3.12
 *----------------------------------------------------------------------------
 *      This code is part of the RealView Run-Time Library.
 *      Copyright (c) 2004-2007 KEIL - An ARM Company. All rights reserved.
 *---------------------------------------------------------------------------*/

#include <stdio.h>
#include <RTL.h>
#include <LM3Sxxxx.H>
#include <string.h>
#include "..\..\..\osram128x64x4.h"

BOOL tick;
BOOL tick2;

char const *hosts[5] = {
   "www.google.com",
   "www.keil.com",
   "www.microsoft.com",
   "www.yahoo.com",
   "www.notexisting.site"
};
unsigned int index;
unsigned int delay;

/*--------------------------- init ------------------------------------------*/

static void init () {
   /* Add System initialisation code here */

   /* Set the clocking to run from the PLL at 50 MHz */
   SysCtlClockSet (SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL |
                   SYSCTL_OSC_MAIN | SYSCTL_XTAL_6MHZ);

   /* Configure the GPIO for the LED. */
   SysCtlPeripheralEnable (SYSCTL_PERIPH_GPIOF);
   GPIOPadConfigSet (GPIO_PORTF_BASE, GPIO_PIN_0, GPIO_STRENGTH_2MA,
                     GPIO_PIN_TYPE_STD);
   GPIODirModeSet (GPIO_PORTF_BASE, GPIO_PIN_0, GPIO_DIR_MODE_OUT);

   /* Configure UART0 for 115200 baud. */
   SysCtlPeripheralEnable (SYSCTL_PERIPH_GPIOA);
   SysCtlPeripheralEnable (SYSCTL_PERIPH_UART0);
   GPIOPinTypeUART (GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
   UARTConfigSet(UART0_BASE, 115200, (UART_CONFIG_WLEN_8 |
                                      UART_CONFIG_STOP_ONE |
                                      UART_CONFIG_PAR_NONE));

   /* Setup and enable the SysTick timer for 100ms. */
   SysTickPeriodSet(SysCtlClockGet() / 10);
   SysTickEnable();
}


/*--------------------------- LED_out ---------------------------------------*/

void LED_out (U32 val) {
   GPIOPinWrite (GPIO_PORTF_BASE, GPIO_PIN_0, val & 1);
}


/*--------------------------- init_display ----------------------------------*/

static void init_display () {
   /* OLED Module init */

   OSRAM128x64x4Init(1000000);
   OSRAM128x64x4Clear ();
   OSRAM128x64x4StringDraw ("    RL-ARM      ", 20, 20, 11);
   OSRAM128x64x4StringDraw ("  DNS example   ", 20, 35, 11);
}


/*--------------------------- timer_poll ------------------------------------*/

static void timer_poll () {
   /* System tick timer running in poll mode */

   if ((HWREG (NVIC_ST_CTRL) >> 16) & 1) {
      /* Timer tick every 100 ms */
      timer_tick ();
      tick  = __TRUE;
      tick2 = __TRUE;
   }
}


/*--------------------------- fputc -----------------------------------------*/

int fputc (int ch, FILE *f)  {
   /* Debug output to serial port. */

   if (ch == '\n')  {
      UARTCharPut (UART0_BASE, '\r');        /* output CR                    */
   }
   UARTCharPut (UART0_BASE, ch);
   return (ch);
}


/*--------------------------- blink_led -------------------------------------*/

static void blink_led () {
   /* Blink the LEDs on MCB-STR9 board */
   static U32 LEDstat = 1;

   if (tick == __TRUE) {
      /* Every 100 ms */
      tick = __FALSE;
      LEDstat = ~LEDstat & 0x01;
      LED_out (LEDstat);
   }
}


/*--------------------------- dns_cbfunc ------------------------------------*/

static void dns_cbfunc (unsigned char event, unsigned char *ip) {
   /* This function is called by the DNS Client when dns event occurs. */

   switch (event) {
      case DNS_EVT_SUCCESS:
         /* Host Address successfully resolved. When IP address is already */
         /* cached, there is no DNS Request sent to remote DNS Server.     */
         printf("IP Address    : %d.%d.%d.%d\n",ip[0],ip[1],ip[2],ip[3]);
         delay = 30;
         break;

      case DNS_EVT_NONAME:
         /* Host Name does not exist in DNS record database. */
         printf("Host name does not exist.\n");
         delay = 30;
         break;

      case DNS_EVT_TIMEOUT:
         /* All DNS Resolver retries used up and timeouts expired. */
         printf("DNS Resolver Timeout expired, Host Address not resolved.\n");
         delay = 30;
         break;

      case DNS_EVT_ERROR:
         /* DNS Protocol Error, invalid or corrupted reply received. */
         printf("DNS Resolver Protocol Error, Host Address not resolved.\n");
         delay = 0;
         return;
   }
   if (++index == 5) {
      index = 0;
   }
}


/*---------------------------------------------------------------------------*/

int main (void) {
   /* Main Thread of the TcpNet */

   init ();
   init_display ();
   init_TcpNet ();

   printf ("\nDNS Resolver Demo Example\n");

   index = 0;
   delay = 0;
   while (1) {
      timer_poll ();
      main_TcpNet ();
      blink_led ();
      if (tick2 == __FALSE) {
         continue;
      }
      tick2 = __FALSE;
      if (++delay == 50) {
         /* After 5 seconds start DNS Resolver. */
         printf ("\nResolving host: %s\n",hosts[index]);
         get_host_by_name ((U8 *)hosts[index],dns_cbfunc);
      }
   }
}


/*----------------------------------------------------------------------------
 * end of file
 *---------------------------------------------------------------------------*/