Mbed OS Reference | DNS.h Source File

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 /*
  * Copyright (c) 2018 ARM Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 /** @file DNS.h Domain Name Service */
 /** @addtogroup netsocket
  * @{ */
 
 #ifndef DNS_H
 #define DNS_H
 
 /** Base class for DNS provider */
 class DNS {
 public:
 
     /** Translate a hostname to an IP address with specific version using network interface name.
      *
      *  The hostname may be either a domain name or an IP address. If the
      *  hostname is an IP address, no network transactions will be performed.
      *
      *  If no stack-specific DNS resolution is provided, the hostname
      *  will be resolve using a UDP socket on the stack.
      *
      *  @param host     Hostname to resolve.
      *  @param address  Pointer to a SocketAddress to store the result.
      *  @param version  IP version of address to resolve, NSAPI_UNSPEC indicates
      *                  version is chosen by the stack (defaults to NSAPI_UNSPEC).
      *  @param interface_name  Network interface name
      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
      */
     virtual nsapi_error_t gethostbyname(const char *host,
                                         SocketAddress *address, nsapi_version_t version = NSAPI_UNSPEC, const char *interface_name = NULL) = 0;
     /** Hostname translation callback for gethostbyname_async.
      *
      *  The callback is called after DNS resolution completes, or a failure occurs.
      *
      *  Callback should not take more than 10ms to execute, otherwise it might
      *  prevent underlying thread processing. A portable user of the callback
      *  should not make calls to network operations due to stack size limitations.
      *  The callback should not perform expensive operations such as socket recv/send
      *  calls or blocking operations.
      *
      *  @param result  NSAPI_ERROR_OK on success, negative error code on failure.
      *  @param address On success, destination for the host SocketAddress.
      */
     typedef mbed::Callback<void (nsapi_error_t result, SocketAddress *address)> hostbyname_cb_t;
 
     /** Translate a hostname to an IP address (asynchronous)
      *
      *  The hostname may be either a domain name or an IP address. If the
      *  hostname is an IP address, no network transactions will be performed.
      *
      *  If no stack-specific DNS resolution is provided, the hostname
      *  will be resolved using a UDP socket on the stack.
      *
      *  The call is non-blocking. The result of the DNS operation is returned by the callback.
      *  If this function returns failure, the callback will not be called. If it is successful,
      *  (the IP address was found from the DNS cache), the callback will be called
      *  before the function returns.
      *
      *  @param host     Hostname to resolve.
      *  @param callback Callback that is called to return the result.
      *  @param version  IP version of address to resolve. NSAPI_UNSPEC indicates that the
      *                  version is chosen by the stack (defaults to NSAPI_UNSPEC).
      *  @param interface_name  Network interface name
      *  @return         NSAPI_ERROR_OK on immediate success,
      *                  negative error code on immediate failure or
      *                  a positive unique ID that represents the hostname translation operation
      *                  and can be passed to cancel.
      */
     virtual nsapi_value_or_error_t gethostbyname_async(const char *host, hostbyname_cb_t callback, nsapi_version_t version = NSAPI_UNSPEC,
                                                        const char *interface_name = NULL) = 0;
 
     /** Cancel asynchronous hostname translation.
      *
      *  When translation is canceled, callback is not called.
      *
      *  @param id       Unique ID of the hostname translation operation returned by gethostbyname_async.
      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
      */
     virtual nsapi_error_t gethostbyname_async_cancel(int id) = 0;
 
     /** Add a domain name server to list of servers to query.
      *
      *  @param address  DNS server host address.
      *  @param interface_name  Network interface name
      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
      */
     virtual nsapi_error_t add_dns_server(const SocketAddress &address, const char *interface_name = NULL) = 0;
 };
 
 #endif
 
 /** @} */
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