iPhone WiFi Subnet Mask and Router Address

Question

I have code that allows me to determine the MAC address and the IP address of the WiFi connection on the iPhone, but I can't figure out how to get the Subnet Mask and Router address for the connection. Can anyone point me in the right direction here?

Answer 1

You can get that information by calling getifaddrs. (I use this function in an app of mine to figure out the iPhone's IP address.)

struct ifaddrs *ifa = NULL, *ifList;
getifaddrs(&ifList); // should check for errors
for (ifa = ifList; ifa != NULL; ifa = ifa->ifa_next) {
   ifa->ifa_addr // interface address
   ifa->ifa_netmask // subnet mask
   ifa->ifa_dstaddr // broadcast address, NOT router address
}
freeifaddrs(ifList); // clean up after yourself

This gets you the subnet mask; for the router address, see this question.

This is all old-school UNIX networking stuff, you'll have to pick out which of the interfaces is the WiFi connection (other stuff like a loopback interface will be in there too). Then you might have to use functions like inet_ntoa() depending on what format you want to read the IP addresses. It's not bad, just tedious and ugly. Have fun!

Answer 2

NSString *address = @"error";
NSString *netmask = @"error";
struct ifaddrs *interfaces = NULL;
struct ifaddrs *temp_addr = NULL;
int success = 0;

// retrieve the current interfaces - returns 0 on success
success = getifaddrs(&interfaces);
if (success == 0)
{
    // Loop through linked list of interfaces
    temp_addr = interfaces;
    while(temp_addr != NULL)
    {
        if(temp_addr->ifa_addr->sa_family == AF_INET)
        {
            // Check if interface is en0 which is the wifi connection on the iPhone

            if([[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"en0"])
            {
                // Get NSString from C String
                address = [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)temp_addr->ifa_addr)->sin_addr)];
                netmask = [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)temp_addr->ifa_netmask)->sin_addr)];
            }
        }

        temp_addr = temp_addr->ifa_next;
    }
}

// Free memory
freeifaddrs(interfaces);
NSLog(@"address %@", address);
NSLog(@"netmask %@", netmask);