Mesh: Enable Nanostack DNS cache usage

Inherit methods gethostbyname, gethostbyname_async and get_dns_server
to Nanostack class. Methods will try to find DNS server address
or DNS query results from Nanostack DNS cache.

connectivity/nanostack/include/nanostack-interface/Nanostack.h

@@ -59,6 +59,58 @@ protected:
     /** @copydoc NetworkStack::get_ip_address */
     nsapi_error_t get_ip_address(SocketAddress *sockAddr) override;
 
+    /** 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.
+     *
+     *  Method first checks Nanostack DNS query result cache. If match is found, then the result is returned immediately.
+     *  Otherwise method calls DNS resolver to find a match.
+     *
+     *  @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 *name, SocketAddress *address, nsapi_version_t version, const char *interface_name);
+
+    /** Translate a hostname to an IP address (asynchronous) using network interface name.
+     *
+     *  The hostname may be either a domain name or a dotted IP address. If the
+     *  hostname is an IP address, no network transactions will be performed.
+     *
+     *  Method first checks Nanostack DNS query result cache. If match is found, then the result is returned immediately.
+     *
+     *  Call is non-blocking. Result of the DNS operation is returned by the callback.
+     *  If this function returns failure, callback will not be called. In case result
+     *  is success (IP address was found from DNS cache), callback will be called
+     *  before function returns.
+     *
+     *  @param host     Hostname to resolve.
+     *  @param callback Callback that is called for 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         0 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 *name, hostbyname_cb_t callback, nsapi_version_t version, const char *interface_name);
+
+    /** Get a domain name server from a list of servers to query
+     *
+     *  Returns a DNS server address for a index. DNS servers are queried from Nanostack DNS cache.
+     *  If returns error no more DNS servers to read.
+     *
+     *  @param index    Index of the DNS server, starts from zero
+     *  @param address  Destination for the host address
+     *  @return         0 on success, negative error code on failure
+     */
+    virtual nsapi_error_t get_dns_server(int index, SocketAddress *address, const char *interface_name);
+
     /** Opens a socket
      *
      *  Creates a network socket and stores it in the specified handle.

connectivity/nanostack/source/Nanostack.cpp

@@ -30,12 +30,20 @@
 #include "mesh_system.h" // from inside mbed-mesh-api
 #include "socket_api.h"
 #include "net_interface.h"
+#include "nsapi_dns.h"
 
 // Uncomment to enable trace
 //#define HAVE_DEBUG
 #include "ns_trace.h"
 #define TRACE_GROUP "nsif"
 
+#define NSIF_DEEP_TRACE
+#ifdef NSIF_DEEP_TRACE
+#define TRACE_DEEP    tr_debug
+#else
+#define TRACE_DEP(...)
+#endif
+
 #define NS_INTERFACE_SOCKETS_MAX  16  //same as NanoStack SOCKET_MAX
 
 #define MALLOC  ns_dyn_mem_alloc
@@ -150,6 +158,50 @@ static int8_t find_interface_by_address(const uint8_t target_addr[16])
     return -1;
 }
 
+static int8_t nanostack_interface_id_parse(const char* interface_name)
+{
+    int8_t interface_id = -1;
+
+    TRACE_DEEP("nanostack_interface_id_parse() %s", interface_name ? interface_name : "null");
+
+    if (!interface_name) {
+        return -1;
+    }
+
+    // parse interface ID from the interface_name
+    if (strlen(interface_name) < 4) {
+        return -1;
+    }
+
+    interface_id = atoi(&interface_name[3]);
+    if (interface_id < 0) {
+        return -1;
+    }
+
+    TRACE_DEEP("parsed interfaceID = %d", interface_id);
+    return interface_id;
+}
+
+static int8_t nanostack_dns_query_result_check(const char *domain_name, SocketAddress *address, const char *interface_name)
+{
+    uint8_t dns_query_addr[16] = {0};
+    int8_t interface_id, ns_query_result;
+
+    interface_id = nanostack_interface_id_parse(interface_name);
+
+    ns_query_result = arm_net_dns_query_result_get(interface_id, dns_query_addr, (char*)domain_name);
+
+    TRACE_DEEP("nanostack_dns_query_result_check(): interface_id=%d, ret=%d, resolved %s to %s",
+            interface_id, ns_query_result, domain_name, trace_ipv6(dns_query_addr));
+
+    if (ns_query_result == 0) {
+        address->set_ip_bytes(dns_query_addr, NSAPI_IPv6);
+        return 0;
+    }
+
+    return -1;
+}
+
 void *NanostackSocket::operator new (std::size_t sz)
 {
     return MALLOC(sz);
@@ -532,6 +584,74 @@ nsapi_error_t Nanostack::get_ip_address(SocketAddress *sockAddr)
     return NSAPI_ERROR_NO_ADDRESS;
 }
 
+nsapi_error_t Nanostack::gethostbyname(const char *name, SocketAddress *address, nsapi_version_t version, const char *interface_name)
+{
+    if (name[0] == '\0') {
+        return NSAPI_ERROR_PARAMETER;
+    }
+    // check for simple ip addresses
+    if (address->set_ip_address(name)) {
+        if (version != NSAPI_UNSPEC && address->get_ip_version() != version) {
+            return NSAPI_ERROR_DNS_FAILURE;
+        }
+        return NSAPI_ERROR_OK;
+    }
+
+    // try nanostack DNS cache, if not found then fallback to dns query
+    if (nanostack_dns_query_result_check(name, address, interface_name) == 0) {
+        return 0;
+    }
+
+    return nsapi_dns_query(this, name, address, interface_name, version);
+}
+
+nsapi_value_or_error_t Nanostack::gethostbyname_async(const char *name, hostbyname_cb_t callback, nsapi_version_t version, const char *interface_name)
+{
+    SocketAddress address;
+
+    if (name[0] == '\0') {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    // check for simple ip addresses
+    if (address.set_ip_address(name)) {
+        if (version != NSAPI_UNSPEC && address.get_ip_version() != version) {
+            return NSAPI_ERROR_DNS_FAILURE;
+        }
+        callback(NSAPI_ERROR_OK, &address);
+        return NSAPI_ERROR_OK;
+    }
+
+    // try nanostack DNS cache, if not found then fallback to dns query
+    if (nanostack_dns_query_result_check(name, &address, interface_name) == 0) {
+        // hit found, return result immediately
+        callback(NSAPI_ERROR_OK, &address);
+        return NSAPI_ERROR_OK;
+    }
+
+    call_in_callback_cb_t call_in_cb = get_call_in_callback();
+    return nsapi_dns_query_async(this, name, callback, call_in_cb, interface_name, version);
+}
+
+nsapi_error_t Nanostack::get_dns_server(int index, SocketAddress *address, const char *interface_name)
+{
+    uint8_t dns_srv_address[16];
+    int8_t interface_id;
+    int8_t ret;
+
+    interface_id = nanostack_interface_id_parse(interface_name);
+
+    ret = arm_net_dns_server_get(interface_id, dns_srv_address, NULL, 0, index);
+
+    if (ret == 0) {
+        address->set_ip_bytes(dns_srv_address, NSAPI_IPv6);
+        TRACE_DEEP("get_dns_server(), index=%d, ret=%d, address=%s", index, ret, trace_ipv6((uint8_t*)address->get_ip_bytes()));
+        return NSAPI_ERROR_OK;
+    }
+
+    return NSAPI_ERROR_NO_ADDRESS;
+}
+
 nsapi_error_t Nanostack::socket_open(void **handle, nsapi_protocol_t protocol)
 {
     // Validate parameters