5.12.1 Execution

main.c - Initialize the device and connect to a server using SSL.

Code summary

Configure the network and server parameters in main.h.

/** Wi-Fi Settings */
#define MAIN_WLAN_SSID                  "DEMO_AP" /**< Destination SSID */
#define MAIN_WLAN_AUTH                  M2M_WIFI_SEC_WPA_PSK /**< Security type */ #define MAIN_WLAN_PSK                   "12345678" /**< Password for Destination SSID */ 

/** All SSL defines */ 
#define MAIN_HOST_NAME                  "www.google.com" 
#define MAIN_HOST_PORT                  443

Initialize the socket module and create the UDP server socket.
```
socketInit(); 
registerSocketCallback(socket_cb, resolve_cb); 
```

Connect to the AP.

/* Connect to AP. */ 
m2m_wifi_connect((char *)MAIN_WLAN_SSID, sizeof(MAIN_WLAN_SSID),
        MAIN_WLAN_AUTH, (char *)MAIN_WLAN_PSK, M2M_WIFI_CH_ALL);

After the device is connected to the AP, the gethostbyname() function will be executed.

static void wifi_cb(uint8_t u8MsgType, void *pvMsg) 
{	
      case M2M_WIFI_REQ_DHCP_CONF:     
      {        
            /* Obtain the IP Address by network name */        
            gethostbyname((uint8_t *)MAIN_HOST_NAME);

Ensure the following configuration in sslConnect():
Call socket() with the SOCKET_FLAGS_SSL bit set in u8Flags parameter.
```
/* Create secure socket */
    if (tcp_client_socket < 0) {
        tcp_client_socket = socket(AF_INET, SOCK_STREAM, SOCKET_FLAGS_SSL);  
        }
```

Configure the SNI for the socket via setsockopt() and option SO_SSL_SNI.

/*Configure the SNI for the socket */
setsockopt(tcp_client_socket, SOL_SSL_SOCKET, SO_SSL_SNI, MAIN_HOST_NAME, sizeof(MAIN_HOST_NAME));

Call set_alpn_list() with parameter pointing to "h2 http/1.1" (this means that HTTP/2 and HTTP/1.1 are both supported).
```
/* Sets the protocol list to be used for ALPN */
set_alpn_list(tcp_client_socket,"h2 http/1.1");
```
After the configuration is applied, try to connect to the SSL server by calling sslConnect().
```
if (sslConnect() != SOCK_ERR_NO_ERROR) {    
    gu8SocketStatus = SocketInit; 
}
```
If successfully connected, the socket_cb() function will be called with the SOCKET_MSG_CONNECT message. The user can check for the ALPN negotiation type in the socket_cb() function with the get_alpn_index() function.
```
/* Check for ALPN negotiation type. */
	      switch (alpn_index)
	      {
		case 1:
		printf("Negotiated HTTP/2.\r\n");
		break;
		case 2:
		printf("Negotiated HTTP/1.1.\r\n");
		break;
		case 0:
		printf("Protocol negotiation did not occur.\r\n");
		break;
	      }
```

Build the program and download it into the board.
Start the application.
Note: To set up an SSL connection, a root certificate must be installed.

AN5305

5.12.1 Execution