DNS.h

00001 /*
00002  * Copyright (c) 2018 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #ifndef DNS_H
00018 #define DNS_H
00019 
00020 class DNS {
00021 public:
00022 
00023     /** Translate a hostname to an IP address with specific version.
00024      *
00025      *  The hostname may be either a domain name or an IP address. If the
00026      *  hostname is an IP address, no network transactions will be performed.
00027      *
00028      *  If no stack-specific DNS resolution is provided, the hostname
00029      *  will be resolve using a UDP socket on the stack.
00030      *
00031      *  @param host     Hostname to resolve.
00032      *  @param address  Pointer to a SocketAddress to store the result.
00033      *  @param version  IP version of address to resolve, NSAPI_UNSPEC indicates
00034      *                  version is chosen by the stack (defaults to NSAPI_UNSPEC).
00035      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
00036      */
00037     virtual nsapi_error_t gethostbyname(const char *host,
00038                                         SocketAddress *address, nsapi_version_t version = NSAPI_UNSPEC ) = 0;
00039 
00040     /** Hostname translation callback for gethostbyname_async.
00041      *
00042      *  The callback is called after DNS resolution completes, or a failure occurs.
00043      *
00044      *  Callback should not take more than 10ms to execute, otherwise it might
00045      *  prevent underlying thread processing. A portable user of the callback
00046      *  should not make calls to network operations due to stack size limitations.
00047      *  The callback should not perform expensive operations such as socket recv/send
00048      *  calls or blocking operations.
00049      *
00050      *  @param result  NSAPI_ERROR_OK on success, negative error code on failure.
00051      *  @param address On success, destination for the host SocketAddress.
00052      */
00053     typedef mbed::Callback<void (nsapi_error_t result, SocketAddress *address)> hostbyname_cb_t;
00054 
00055     /** Translate a hostname to an IP address (asynchronous).
00056      *
00057      *  The hostname may be either a domain name or an IP address. If the
00058      *  hostname is an IP address, no network transactions will be performed.
00059      *
00060      *  If no stack-specific DNS resolution is provided, the hostname
00061      *  will be resolved using a UDP socket on the stack.
00062      *
00063      *  The call is non-blocking. The result of the DNS operation is returned by the callback.
00064      *  If this function returns failure, the callback will not be called. If it is successful,
00065      *  (the IP address was found from the DNS cache), the callback will be called
00066      *  before the function returns.
00067      *
00068      *  @param host     Hostname to resolve.
00069      *  @param callback Callback that is called to return the result.
00070      *  @param version  IP version of address to resolve. NSAPI_UNSPEC indicates that the
00071      *                  version is chosen by the stack (defaults to NSAPI_UNSPEC).
00072      *  @return         NSAPI_ERROR_OK on immediate success,
00073      *                  negative error code on immediate failure or
00074      *                  a positive unique ID that represents the hostname translation operation
00075      *                  and can be passed to cancel.
00076      */
00077     virtual nsapi_value_or_error_t gethostbyname_async(const char *host, hostbyname_cb_t callback,
00078                                                        nsapi_version_t version = NSAPI_UNSPEC ) = 0;
00079 
00080     /** Cancel asynchronous hostname translation.
00081      *
00082      *  When translation is canceled, callback is not called.
00083      *
00084      *  @param id       Unique ID of the hostname translation operation returned by gethostbyname_async.
00085      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
00086      */
00087     virtual nsapi_error_t gethostbyname_async_cancel(int id) = 0;
00088 
00089     /** Add a domain name server to list of servers to query.
00090      *
00091      *  @param address  DNS server host address.
00092      *  @return         NSAPI_ERROR_OK on success, negative error code on failure.
00093      */
00094     virtual nsapi_error_t add_dns_server(const SocketAddress &address) = 0;
00095 };
00096 
00097 #endif