Add support for hostname request in lwIP interface

connectivity/lwipstack/source/LWIPInterface.cpp

@@ -433,6 +433,7 @@ LWIP::Interface::Interface() :
 nsapi_error_t LWIP::add_ethernet_interface(EMAC &emac, bool default_if, OnboardNetworkStack::Interface **interface_out, NetworkInterface *user_network_interface)
 {
 #if LWIP_ETHERNET
+    const char *hostname;
     Interface *interface = new (std::nothrow) Interface();
     if (!interface) {
         return NSAPI_ERROR_NO_MEMORY;
@@ -441,6 +442,11 @@ nsapi_error_t LWIP::add_ethernet_interface(EMAC &emac, bool default_if, OnboardN
     interface->memory_manager = &memory_manager;
     interface->ppp_enabled = false;
 
+    hostname = user_network_interface->get_hostname();
+    if(hostname) {
+        netif_set_hostname(&interface->netif, hostname);
+    }
+
 #if (MBED_MAC_ADDRESS_SUM != MBED_MAC_ADDR_INTERFACE)
     netif->interface.hwaddr[0] = MBED_MAC_ADDR_0;
     netif->interface.hwaddr[1] = MBED_MAC_ADDR_1;

connectivity/netsocket/include/netsocket/EMACInterface.h

@@ -83,6 +83,12 @@ class EMACInterface : public virtual NetworkInterface {
     /** @copydoc NetworkInterface::disconnect */
     nsapi_error_t disconnect() override;
 
+    /** @copydoc NetworkInterface::get_hostname */
+    const char *get_hostname() override;
+
+    /** @copydoc NetworkInterface::set_hostname */
+    nsapi_error_t set_hostname(const char *hostname) override;
+
     /** @copydoc NetworkInterface::get_mac_address */
     const char *get_mac_address() override;
 
@@ -146,6 +152,8 @@ class EMACInterface : public virtual NetworkInterface {
     OnboardNetworkStack::Interface *_interface = nullptr;
     bool _dhcp = true;
     bool _blocking = true;
+    bool _hostname_set = false;
+    char _hostname[NSAPI_HOSTNAME_SIZE];
     bool _hw_mac_addr_set = false;
     char _mac_address[NSAPI_MAC_SIZE];
     char _ip_address[NSAPI_IPv6_SIZE] {};

connectivity/netsocket/include/netsocket/NetworkInterface.h

@@ -90,6 +90,22 @@ class NetworkInterface: public DNS {
      */
     virtual void set_as_default();
 
+    /** Get hostname.
+     *
+     *  @return         Hostname if configured, null otherwise
+     */
+    virtual const char *get_hostname();
+
+    /** Set hostname.
+     *
+     *  @param          hostname Hostname string
+     *  @retval         NSAPI_ERROR_OK on success
+     *  @retval         NSAPI_ERROR_UNSUPPORTED if this feature is not supported
+     *  @retval         NSAPI_ERROR_PARAMETER if hostname is not valid
+     *  @retval         NSAPI_ERROR_BUSY if hostname can't be set
+     */
+    virtual nsapi_error_t set_hostname(const char *hostname);
+
     /** Get the local MAC address.
      *
      *  Provided MAC address is intended for info or debug purposes and

connectivity/netsocket/include/netsocket/nsapi_types.h

@@ -196,6 +196,16 @@ typedef enum nsapi_security {
  */
 #define NSAPI_IP_BYTES NSAPI_IPv6_BYTES
 
+/** Maximum size of hostname
+ *
+ *  According to RFC 1034 [1], Section 3.1 "Name space specifications and
+ *  terminology", 63 is the maximum size of a hostname. +1 for the string
+ *  terminator.
+ *
+ *  [1] https://www.rfc-editor.org/rfc/rfc1034
+ */
+#define NSAPI_HOSTNAME_SIZE 64
+
 /** Maximum size of MAC address representation
  */
 #define NSAPI_MAC_SIZE 18

connectivity/netsocket/source/EMACInterface.cpp

@@ -88,6 +88,32 @@ nsapi_error_t EMACInterface::disconnect()
     return NSAPI_ERROR_NO_CONNECTION;
 }
 
+const char *EMACInterface::get_hostname()
+{
+    if (_hostname_set) {
+        return _hostname;
+    }
+    return nullptr;
+}
+
+nsapi_error_t EMACInterface::set_hostname(const char *hostname)
+{
+    if (!hostname || strlen(hostname) > NSAPI_HOSTNAME_SIZE-1) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    if (_interface) {
+        // can't set hostname once initialized
+        return NSAPI_ERROR_BUSY;
+    }
+
+    memset(_hostname, 0, NSAPI_HOSTNAME_SIZE);
+    strncpy(_hostname, hostname, NSAPI_HOSTNAME_SIZE-1);
+    _hostname_set = true;
+
+    return NSAPI_ERROR_OK;
+}
+
 const char *EMACInterface::get_mac_address()
 {
     if (_interface && _interface->get_mac_address(_mac_address, sizeof(_mac_address))) {

connectivity/netsocket/source/NetworkInterface.cpp

@@ -29,6 +29,16 @@ void NetworkInterface::set_as_default()
 
 }
 
+const char *NetworkInterface::get_hostname()
+{
+    return 0;
+}
+
+nsapi_error_t NetworkInterface::set_hostname(const char *hostname)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
 const char *NetworkInterface::get_mac_address()
 {
     return 0;