通过函数get_host_by_name实现DNS域名解析的过程，Full Debug状态的调试打印

eric2013

armfly

硬汉 2022/1/13 20:42:32
方法一，阻塞的函数。
NET_ADDR addr;
char ip_ascii[40];

if (netDNSc_GetHostByNameX ("www.arm.com", NET_ADDR_IP4, &addr) == netOK) {
  // Success, 'addr' holds resolved IP address
  netIP_ntoa (addr->addr_type, adr->addr, ip_ascii, sizeof(ip_ascii));
  printf("IP Address: %s\n", ip_ascii);
}

硬汉 2022/1/13 20:42:58
方法二，非阻塞的，在回调函数完成。
static void dns_cbfunc (netDNSc_Event event, const NET_ADDR *addr);

if (netDNSc_GetHostByName ("www.arm.com", NET_ADDR_IP4, dns_cbfunc) == netOK) {
  // Started, will complete on callback notification
}

static void dns_cbfunc (netDNSc_Event event, const NET_ADDR *addr) {
  char ip_ascii[40];
  
  switch (event) {
    case netDNSc_EventSuccess:
      // Host Address successfully resolved
      netIP_ntoa (addr->addr_type, adr->addr, ip_ascii, sizeof(ip_ascii));
      printf("IP Address: %s\n", ip_ascii);
      break;

    case netDNSc_EventNotResolved:
      // Error, host name does not exist in DNS record database
      break;

    case netDNSc_EventTimeout:
      // Error, DNS resolver timeout expired
      break;

    case netDNSc_EventError:
      // Error, DNS protocol error occurred
      break;
  }
}