Internet mode guide

DSWifi supports Internet communications. However, DSi mode WiFi isn't supported yet, so it is restricted to open and WEP-encrypted networks. DSWifi includes the library sgIP to handle connections. It supports IPv4, as well as TCP and UDP.

1. Initialization

You can initialize the library in autoconnect mode or in manual connection mode. With autoconnect mode DSWifi will check the WiFi networks stored in the firmware of the console and it will try to connect to them:

Wifi_InitDefault(WFC_CONNECT);

However, this isn't very flexible. The function will simply wait until the connection works (or until the library times out). It will also make it impossible to switch between local multiplayer and Internet modes.

It's generally better to initialize the library in manual mode and to give the user the option to do different things. Initialize the library with this (it starts by default in Internet mode, not multiplayer mode):

Wifi_InitDefault(INIT_ONLY);

Hardware timer 3 will be used by the WiFi library after this call.

1.1 Connect to WFC settings

You can start autoconnect mode by calling:

Wifi_AutoConnect();

1.2 Manually look for access points

You can manually look for access points like this, for example:

// Set the library in scan mode
Wifi_ScanMode();
 
while (1)
{
    swiWaitForVBlank();
 
    // Get find out how many APs there are in the area
    int count = Wifi_GetNumAP();
 
    printf("Number of AP: %d\n", count);
    printf("\n");
 
    for (int i = 0; i < count; i++)
    {
        Wifi_AccessPoint ap;
        Wifi_GetAPData(i, &ap);
 
        const char *security = "Open";
        if (ap.flags & WFLAG_APDATA_WPA)
            security = "WPA ";
        else if (ap.flags & WFLAG_APDATA_WEP)
            security = "WEP ";
 
        // WPA isn't supported!
 
        printf("[%.24s]\n", ap.ssid)
        printf("%s | Channel %2d | RSSI %u\n", security, ap.channel, ap.rssi);
        printf("\n");
    }
}

After you have decided which AP to connect to:

// Setting everything to 0 will make DHCP determine the IP address. You can also
// set the settings manually if you want.
Wifi_SetIP(0, 0, 0, 0, 0);
 
// If the access point requires a WEP password, ask the user to provide it
if (AccessPoint.flags & WFLAG_APDATA_WEP)
{
    // For 5 character long passwords, use WEPMODE_40BIT. For 13 character long
    // passwords, use WEPMODE_128BIT.
    int wepmode = WEPMODE_128BIT;
    const char *password = "MyPassword123";
    Wifi_ConnectAP(&AccessPoint, wepmode, 0, (u8 *)password);
}
else
{
    Wifi_ConnectAP(&AccessPoint, WEPMODE_NONE, 0, 0);
}

Wifi_DisconnectAP() expects WEP keys as a string (usually called "ASCII" key). If you have an hexadecimal key you have to save it as a string of hexadecimal values. For example, 6162636465 needs to be passed to the function as { 0x61, 0x62, 0x63, 0x64, 0x65 }, not as "6162636465".

1.3 Wait until you connect to the AP

Regardless of which mode you used to start the connection to the AP, wait for the connection to be completed (or to fail!):

while (1)
{
    swiWaitForVBlank();
 
    int status = Wifi_AssocStatus();
 
    if (status == ASSOCSTATUS_CANNOTCONNECT)
    {
        // We can't connect to this host, try to connect to a different one!
    }
 
    if (status == ASSOCSTATUS_ASSOCIATED)
    {
        // Success!
    }
}

1.4 Disconnect from the AP

Eventually, when you want to leave this AP:

Wifi_DisconnectAP();

If you are done using wireless mode you can disable it to save power by calling:

Wifi_DisableWifi();

2. Get connection settings

You can get information like the IP address like this:

struct in_addr ip, gateway, mask, dns1, dns2;
ip = Wifi_GetIPInfo(&gateway, &mask, &dns1, &dns2);
 
printf("\n");
printf("Connection information:\n");
printf("\n");
printf("IP:      %s\n", inet_ntoa(ip));
printf("Gateway: %s\n", inet_ntoa(gateway));
printf("Mask:    %s\n", inet_ntoa(mask));
printf("DNS1:    %s\n", inet_ntoa(dns1));
printf("DNS2:    %s\n", inet_ntoa(dns2));
printf("\n");

3. Use libc to access the Internet

3.1 Resolve host IPs

You can obtain the IP of a host like this:

const char *url = "www.wikipedia.com";
 
struct hostent *host = gethostbyname(url);
 
if (host)
    printf("IP: %s\n", inet_ntoa(*(struct in_addr *)host->h_addr_list[0]));
else
    printf("Could not get IP\n");

3.2 Communicate using sockets

You can create TCP or UDP sockets with:

socket(AF_INET, SOCK_STREAM, 0); // TCP
socket(AF_INET, SOCK_DGRAM, 0); // UDP

Then, you can use connect(), send(), recv(), shutdown() and closesocket().

Note that, by default, sockets start in blocking mode. You can switch to non-blocking mode with:

int opt = 1;
int rc = ioctl(my_socket, FIONBIO, (char *)&opt);