[参考译文] EK-TM4C129EXL：使用静态 IP HttpGet TI-RTOS 示例时如何添加 DNS 服务器

您好！

 我不确定。 您可能需要使用 getaddrinfo 来查找 www.example.com 的 IP 地址。 我使用 getaddrinfo 找到这个示例可能会有所帮助。  

#include <string.h>

#include <xdc/std.h>
#include <xdc/runtime/Error.h>
#include <xdc/runtime/System.h>

#include <ti/sysbios/BIOS.h>
#include <ti/sysbios/knl/Task.h>
#include <ti/drivers/GPIO.h>

#include <dns.h>

/* Example/Board Header file */
#include "Board.h"

#define DNSHANDLERSTACK 2048
#define NUM_HOST 4
#define INET_ADDRSTRLEN 16
static char strIp[INET_ADDRSTRLEN];


/*
 * List of host names to resolve by DNS
 */
const char *hostname[NUM_HOST] = { "pool.ntp.org", "www.google.com", "api.openweathermap.org", "www.ti.com" };
/*
 *  ======== dnsWorker ========
 *  Task to request DNS service
 */
Void dnsWorker(UArg arg0, UArg arg1)
{
    struct addrinfo *server_data = NULL;
    int result;
    int i;

    for (i=0;i<NUM_HOST;i++)
    {
        System_printf("!!!!!!!!!!\n", result);
        System_flush();

        /*
         * Given the host name, which identify a Internet host, getaddrinfo
         * returns one or more addrinfo structure, each of which contains
         * an Internet address that can be specified in a call to bind or
         * connect
         */
        result = getaddrinfo(hostname[i], "0", NULL, &server_data);

        if (result == 0 && server_data != NULL)
        {
            struct sockaddr addr = *(server_data->ai_addr);
            /*
             * convert IP address structure to string format
             */
            inet_ntop(AF_INET, &((struct sockaddr_in *)&addr)->sin_addr, strIp, INET_ADDRSTRLEN);
            System_printf("HOSTNAME: %s\tResolved address:%s\n", hostname[i],strIp);
            System_flush();

            freeaddrinfo(server_data);
            server_data = NULL;
        }

        Task_sleep(1000); // Sleep for 1 seconds
    }
}

/*
 *  ======== dnsHooks ========
 *  Creates new Task to request DNS service.
 */
Void dnsHooks(UArg arg0, UArg arg1)
{

    Task_Handle        taskHandle;
    Task_Params        taskParams;
    Error_Block        eb;

    /* Init the Error_Block */
    Error_init(&eb);

    /* Initialize the defaults and set the parameters. */
    Task_Params_init(&taskParams);
    taskParams.stackSize = DNSHANDLERSTACK;
    taskParams.priority = 1;
    taskHandle = Task_create((Task_FuncPtr)dnsWorker, &taskParams, &eb);
    if (taskHandle == NULL) {
        System_printf("Error: Failed to create new Task\n");
    }

}

/*
 *  ======== main ========
 */
int main(void)
{
    /* Call board init functions */
    Board_initGeneral();
    Board_initGPIO();
    Board_initEMAC();

    System_printf("Starting the DNS request example\nSystem provider is set to "
                  "SysMin. Halt the target to view any SysMin contents in"
                  " ROV.\n");
    /* SysMin will only print to the console when you call flush or exit */
    System_flush();

    /* Start BIOS */
    BIOS_start();

    return (0);
}