mbed_example / Mbed OS DNS_GetHostbyNameAsync_Example

An example how to make asynchronous DNS host name resolution.

main.cpp@0:d0f7d306a900, 2018-05-25 (annotated)

Committer:
mikaleppanen
Date:
Fri May 25 12:25:32 2018 +0000
Revision:
0:d0f7d306a900
Example how to make asynchronous DNS get host by name operation

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mikaleppanen 0:d0f7d306a900 1 #include "mbed.h"
mikaleppanen 0:d0f7d306a900 2 #include "nsapi_types.h"
mikaleppanen 0:d0f7d306a900 3 #include "EthernetInterface.h"
mikaleppanen 0:d0f7d306a900 4 #include "SocketAddress.h"
mikaleppanen 0:d0f7d306a900 5 #include "Semaphore.h"
mikaleppanen 0:d0f7d306a900 6
mikaleppanen 0:d0f7d306a900 7 rtos::Semaphore callback_semaphore;
mikaleppanen 0:d0f7d306a900 8 SocketAddress address;
mikaleppanen 0:d0f7d306a900 9 nsapi_error_t result;
mikaleppanen 0:d0f7d306a900 10
mikaleppanen 0:d0f7d306a900 11 // Callback for asynchronous host name resolution
mikaleppanen 0:d0f7d306a900 12 void hostbyname_callback(nsapi_error_t res, SocketAddress *addr)
mikaleppanen 0:d0f7d306a900 13 {
mikaleppanen 0:d0f7d306a900 14 // Store result and release semaphore
mikaleppanen 0:d0f7d306a900 15 result = res;
mikaleppanen 0:d0f7d306a900 16 address = *addr;
mikaleppanen 0:d0f7d306a900 17 callback_semaphore.release();
mikaleppanen 0:d0f7d306a900 18 }
mikaleppanen 0:d0f7d306a900 19
mikaleppanen 0:d0f7d306a900 20 int main()
mikaleppanen 0:d0f7d306a900 21 {
mikaleppanen 0:d0f7d306a900 22 // Initialise network interface
mikaleppanen 0:d0f7d306a900 23 EthernetInterface eth;
mikaleppanen 0:d0f7d306a900 24 eth.connect();
mikaleppanen 0:d0f7d306a900 25
mikaleppanen 0:d0f7d306a900 26 // Initiate asynchronous DNS host name resolution
mikaleppanen 0:d0f7d306a900 27 eth.gethostbyname_async("www.mbed.com", hostbyname_callback);
mikaleppanen 0:d0f7d306a900 28
mikaleppanen 0:d0f7d306a900 29 // Wait for callback semaphore
mikaleppanen 0:d0f7d306a900 30 callback_semaphore.wait();
mikaleppanen 0:d0f7d306a900 31
mikaleppanen 0:d0f7d306a900 32 // Print result
mikaleppanen 0:d0f7d306a900 33 printf("Result %s, Address %s\r\n", result == NSAPI_ERROR_OK ? "OK" : "FAIL",
mikaleppanen 0:d0f7d306a900 34 result == NSAPI_ERROR_OK ? address.get_ip_address() : "NONE");
mikaleppanen 0:d0f7d306a900 35
mikaleppanen 0:d0f7d306a900 36 // Disconnect network interface
mikaleppanen 0:d0f7d306a900 37 eth.disconnect();
mikaleppanen 0:d0f7d306a900 38 }