[dns] simplify defines name and clean up (#3209)

include/openthread/dns.h

@@ -54,8 +54,8 @@ extern "C" {
 
 #define OT_DNS_MAX_HOSTNAME_LENGTH 62 ///< Maximum allowed hostname length (maximum label size - 1 for compression).
 
-#define OT_DNS_DEFAULT_DNS_SERVER_IP "2001:4860:4860::8888" ///< Defines default DNS Server address - Google DNS.
-#define OT_DNS_DEFAULT_DNS_SERVER_PORT 53                   ///< Defines default DNS Server port.
+#define OT_DNS_DEFAULT_SERVER_IP "2001:4860:4860::8888" ///< Defines default DNS Server address - Google DNS.
+#define OT_DNS_DEFAULT_SERVER_PORT 53                   ///< Defines default DNS Server port.
 
 /**
  * This structure implements DNS Query parameters.

src/cli/cli.cpp

@@ -797,7 +797,7 @@ exit:
 void Interpreter::ProcessDns(int argc, char *argv[])
 {
     otError          error = OT_ERROR_NONE;
-    long             port  = OT_DNS_DEFAULT_DNS_SERVER_PORT;
+    long             port  = OT_DNS_DEFAULT_SERVER_PORT;
     Ip6::MessageInfo messageInfo;
     otDnsQuery       query;
 
@@ -820,7 +820,7 @@ void Interpreter::ProcessDns(int argc, char *argv[])
         else
         {
             // Use IPv6 address of default DNS server.
-            SuccessOrExit(error = messageInfo.GetPeerAddr().FromString(OT_DNS_DEFAULT_DNS_SERVER_IP));
+            SuccessOrExit(error = messageInfo.GetPeerAddr().FromString(OT_DNS_DEFAULT_SERVER_IP));
         }
 
         if (argc > 3)

src/core/api/dns_api.cpp

@@ -28,7 +28,7 @@
 
 /**
  * @file
- *   This file implements the OpenThread UDP API.
+ *   This file implements the OpenThread DNSv6 API.
  */
 
 #include "openthread-core-config.h"

src/core/net/dns_client.cpp

@@ -471,10 +471,7 @@ void Client::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessag
 
     VerifyOrExit((message = FindRelatedQuery(responseHeader, queryMetadata)) != NULL);
 
-    if (responseHeader.GetResponseCode() != Header::kResponseSuccess)
-    {
-        ExitNow(error = OT_ERROR_FAILED);
-    }
+    VerifyOrExit(responseHeader.GetResponseCode() == Header::kResponseSuccess, error = OT_ERROR_FAILED);
 
     // Parse and check the question section.
     SuccessOrExit(error = CompareQuestions(aMessage, *message, offset));

src/core/net/dns_client.hpp

@@ -193,14 +193,6 @@ public:
      */
     otError Query(const otDnsQuery *aQuery, otDnsResponseHandler aHandler, void *aContext);
 
-    /**
-     * This method returns a port number used by DNS client.
-     *
-     * @returns A port number.
-     *
-     */
-    uint16_t GetPort(void) { return mSocket.GetSockName().mPort; };
-
 private:
     /**
      * Retransmission parameters.