Question

Every time I start build my Xcode Project, I get this in the console:

<CFData 0x100516c60 [0x7fff71adaea0]>{length = 6, capacity = 6, bytes = 0x0022412b03ad}

I have no idea, what it means and what it’s causing it.

Can someone help me?

Thx!

Edit:
I think this method creates it:

//
//  PrimaryMac.m
//  Network Radar
//
//  Created by Daniel Diener on 06.07.11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "PrimaryMac.h"
#include <stdio.h>
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include "if_types.h"
#include "route.h"
#include "if_ether.h"
#include <netinet/in.h>


#include <arpa/inet.h>

#include <err.h>
#include <errno.h>
#include <netdb.h>

#include <paths.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <CoreFoundation/CoreFoundation.h>

#include <IOKit/IOKitLib.h>
#include <IOKit/network/IOEthernetInterface.h>
#include <IOKit/network/IONetworkInterface.h>
#include <IOKit/network/IOEthernetController.h>

@implementation PrimaryMac
@synthesize localMac, remoteMac;

static kern_return_t FindEthernetInterfaces(io_iterator_t *matchingServices);
static kern_return_t GetMACAddress(io_iterator_t intfIterator, UInt8 *MACAddress, UInt8 bufferSize);

- (id)init
{
    self = [super init];
    if (self) {

    }

    return self;
}



//LOCAL MAC:::::::::::::::::::


// Returns an iterator containing the primary (built-in) Ethernet interface. The caller is responsible for
// releasing the iterator after the caller is done with it.
static kern_return_t FindEthernetInterfaces(io_iterator_t *matchingServices)
{
    kern_return_t           kernResult; 
    CFMutableDictionaryRef  matchingDict;
    CFMutableDictionaryRef  propertyMatchDict;

    // Ethernet interfaces are instances of class kIOEthernetInterfaceClass. 
    // IOServiceMatching is a convenience function to create a dictionary with the key kIOProviderClassKey and 
    // the specified value.
    matchingDict = IOServiceMatching(kIOEthernetInterfaceClass);

    // Note that another option here would be:
    // matchingDict = IOBSDMatching("en0");
    // but en0: isn't necessarily the primary interface, especially on systems with multiple Ethernet ports.

    if (NULL == matchingDict) {
        printf("IOServiceMatching returned a NULL dictionary.\n");
    }
    else {
        // Each IONetworkInterface object has a Boolean property with the key kIOPrimaryInterface. Only the
        // primary (built-in) interface has this property set to TRUE.

        // IOServiceGetMatchingServices uses the default matching criteria defined by IOService. This considers
        // only the following properties plus any family-specific matching in this order of precedence 
        // (see IOService::passiveMatch):
        //
        // kIOProviderClassKey (IOServiceMatching)
        // kIONameMatchKey (IOServiceNameMatching)
        // kIOPropertyMatchKey
        // kIOPathMatchKey
        // kIOMatchedServiceCountKey
        // family-specific matching
        // kIOBSDNameKey (IOBSDNameMatching)
        // kIOLocationMatchKey

        // The IONetworkingFamily does not define any family-specific matching. This means that in            
        // order to have IOServiceGetMatchingServices consider the kIOPrimaryInterface property, we must
        // add that property to a separate dictionary and then add that to our matching dictionary
        // specifying kIOPropertyMatchKey.

        propertyMatchDict = CFDictionaryCreateMutable(kCFAllocatorDefault, 0,
                                                      &kCFTypeDictionaryKeyCallBacks,
                                                      &kCFTypeDictionaryValueCallBacks);

        if (NULL == propertyMatchDict) {
            printf("CFDictionaryCreateMutable returned a NULL dictionary.\n");
        }
        else {
            // Set the value in the dictionary of the property with the given key, or add the key 
            // to the dictionary if it doesn't exist. This call retains the value object passed in.
            CFDictionarySetValue(propertyMatchDict, CFSTR(kIOPrimaryInterface), kCFBooleanTrue); 

            // Now add the dictionary containing the matching value for kIOPrimaryInterface to our main
            // matching dictionary. This call will retain propertyMatchDict, so we can release our reference 
            // on propertyMatchDict after adding it to matchingDict.
            CFDictionarySetValue(matchingDict, CFSTR(kIOPropertyMatchKey), propertyMatchDict);
            CFRelease(propertyMatchDict);
        }
    }

    // IOServiceGetMatchingServices retains the returned iterator, so release the iterator when we're done with it.
    // IOServiceGetMatchingServices also consumes a reference on the matching dictionary so we don't need to release
    // the dictionary explicitly.
    kernResult = IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, matchingServices);    
    if (KERN_SUCCESS != kernResult) {
        printf("IOServiceGetMatchingServices returned 0x%08x\n", kernResult);
    }

    return kernResult;
}

// Given an iterator across a set of Ethernet interfaces, return the MAC address of the last one.
// If no interfaces are found the MAC address is set to an empty string.
// In this sample the iterator should contain just the primary interface.
static kern_return_t GetMACAddress(io_iterator_t intfIterator, UInt8 *MACAddress, UInt8 bufferSize)
{
    io_object_t     intfService;
    io_object_t     controllerService;
    kern_return_t   kernResult = KERN_FAILURE;

    // Make sure the caller provided enough buffer space. Protect against buffer overflow problems.
    if (bufferSize < kIOEthernetAddressSize) {
        return kernResult;
    }

    // Initialize the returned address
    bzero(MACAddress, bufferSize);

    // IOIteratorNext retains the returned object, so release it when we're done with it.
    while ((intfService = IOIteratorNext(intfIterator)))
        {
        CFTypeRef   MACAddressAsCFData;        

        // IONetworkControllers can't be found directly by the IOServiceGetMatchingServices call, 
        // since they are hardware nubs and do not participate in driver matching. In other words,
        // registerService() is never called on them. So we've found the IONetworkInterface and will 
        // get its parent controller by asking for it specifically.

        // IORegistryEntryGetParentEntry retains the returned object, so release it when we're done with it.
        kernResult = IORegistryEntryGetParentEntry(intfService,
                                                   kIOServicePlane,
                                                   &controllerService);

        if (KERN_SUCCESS != kernResult) {
            printf("IORegistryEntryGetParentEntry returned 0x%08x\n", kernResult);
        }
        else {
            // Retrieve the MAC address property from the I/O Registry in the form of a CFData
            MACAddressAsCFData = IORegistryEntryCreateCFProperty(controllerService,
                                                                 CFSTR(kIOMACAddress),
                                                                 kCFAllocatorDefault,
                                                                 0);
            if (MACAddressAsCFData) {
                CFShow(MACAddressAsCFData); // for display purposes only; output goes to stderr

                // Get the raw bytes of the MAC address from the CFData
                CFDataGetBytes(MACAddressAsCFData, CFRangeMake(0, kIOEthernetAddressSize), MACAddress);
                CFRelease(MACAddressAsCFData);
            }

            // Done with the parent Ethernet controller object so we release it.
            (void) IOObjectRelease(controllerService);
        }

        // Done with the Ethernet interface object so we release it.
        (void) IOObjectRelease(intfService);
        }

    return kernResult;
}

- (void)createLocalMac{
    kern_return_t   kernResult = KERN_SUCCESS;
    io_iterator_t   intfIterator;
    UInt8           MACAddress[kIOEthernetAddressSize];

    kernResult = FindEthernetInterfaces(&intfIterator);

    if (KERN_SUCCESS != kernResult) {
        printf("FindEthernetInterfaces returned 0x%08x\n", kernResult);
    }
    else {
        kernResult = GetMACAddress(intfIterator, MACAddress, sizeof(MACAddress));

        if (KERN_SUCCESS != kernResult) {
            printf("GetMACAddress returned 0x%08x\n", kernResult);
        }
        else {
            localMac = [NSString stringWithFormat:@"%02x:%02x:%02x:%02x:%02x:%02x",
                   MACAddress[0], MACAddress[1], MACAddress[2], MACAddress[3], MACAddress[4], MACAddress[5]];
        }
    }

    (void) IOObjectRelease(intfIterator);   // Release the iterator.
}


//REMOTE MAC:::::::::::::::::::


- (void)createRemoteMac:(NSString *)ipAddr{
    NSString *ret = nil;

    in_addr_t addr = inet_addr([ipAddr UTF8String]);

    size_t needed;
    char *buf, *next;

    struct rt_msghdr *rtm;
    struct sockaddr_inarp *sin;
    struct sockaddr_dl *sdl;

    int mib[6];

    mib[0] = CTL_NET;
    mib[1] = PF_ROUTE;
    mib[2] = 0;
    mib[3] = AF_INET;
    mib[4] = NET_RT_FLAGS;
    mib[5] = RTF_LLINFO;

    if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), NULL, &needed, NULL, 0) < 0)
        err(1, "route-sysctl-estimate");

    if ((buf = (char*)malloc(needed)) == NULL)
        err(1, "malloc");

    if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), buf, &needed, NULL, 0) < 0)
        err(1, "retrieval of routing table");

    for (next = buf; next < buf + needed; next += rtm->rtm_msglen) {

        rtm = (struct rt_msghdr *)next;
        sin = (struct sockaddr_inarp *)(rtm + 1);
        sdl = (struct sockaddr_dl *)(sin + 1);

        if (addr != sin->sin_addr.s_addr || sdl->sdl_alen < 6)
            continue;

        u_char *cp = (u_char*)LLADDR(sdl);

        ret = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
               cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]];

        break;
    }

    free(buf);

    remoteMac = ret;
}

- (void)dealloc {
    [remoteMac release];
    [localMac release];
    [super dealloc];
}

@end

I use it to get the active interface’s MAC address.

Answer 1

Your print statement is happening on this line using CFShow. Just comment that out 🙂

if (MACAddressAsCFData) {

     //Comment out the CFShow here
     CFShow(MACAddressAsCFData); // for display purposes only; output goes to stderr